Reviews

Wanyi Zhu, 5/19/2022

Nudibranchs are a group of gastropod mollusks that contain indicator species of ocean conditions and have a variety of predator defense strategies. They've been studied for their symbiosis with bacteria, but this study investigates their association with RNA viruses, in hopes of tracing the distribution of pathogenic viruses in nudibranch habitats and uncovering potential antiviral responses.

Researcher Umberto Rosani conducted a meta-transcriptomic analysis on the transcriptomic data of 35 species of nudibranchs from the Sequence Read Archive, using annotation and search tools including DIAMOND, palmscan, and VirSorter2 to identify viral sequences.

He identified contigs, or sequences, matching the phyla Kitrinoviricota, Negarnaviricota and Pisuviricota, as well as many unclassified viruses. Multiple contigs had similarities with the Beihai picorna-like virus 75, Wenzhou picorna-like virus 46, and different viruses in the phylum Pisuviricota. These viruses are associated with infecting crustaceans, arthropods, gastropods (as expected), poriferans, and even plants and bacteria.

The methods used complemented each other, beginning with using blastx to classify contigs against the NCBI non-redundant protein database, though nudibranch viruses were poorly represented, causing false positives. To work around this, palmscan and Virsorter2 used viral RdRP footprints and viral hallmark genes to avoid identifying incomplete viruses. Separately, these methods found a total of 552 contigs, but combining them resulted in a core set of 19 viruses.

Given that nudibranch microbes are not well-researched, especially viruses, this study provides a basis for further research on nudibranch symbiosis and antiviral defenses, with an added strength of multiple complementary methods.

Faith Okamoto, 6/7/2021, faith.purpleflower@gmail.com

What does the dolphin say? Lots of stuff - the common bottlenose dolphin is (scientifically) notorious for their "vast acoustic repertoire", or the large number of different sounds they can and do produce. The exact function of all of these sounds is under study. Most research has focused on whistles, but there are also clicks, pulses, etc.. We know the environment has some effect on which kinds of whistles are produced, however, this line of research has been confined to local investigation.

This study looked at all the sounds that bottlenose dolphins make, across 9 different populations, from Panama to Portugal. These were classified into broad categories and then into smaller sub-types. While every broad category was present at every site, many sub-types were missing from some places. Some sub-types were only present at one location, some were only missing from one location, etc.. The researchers used a dissimilarity algorithm to draw a relationship tree showing the connections between the locations. (Think like a branching evolution diagram.)

That's the data. The scientists caution that different locations had data collection occur at different times, and with different methodologies (translation-in-context: systems of methods for gathering data). Thus nothing is directly comparable, but broader connections can be drawn nevertheless.

First off, this is further confirmation of the diversity of noises from dolphins. It's also interesting that the smallest group by population size has one of the largest number of distinct vocalizations; current theory is that more complex social dynamics would warrant more kinds of sounds. Social signals - whistles, brays (similar to birds), etc. - were the only ones with significant divergence; this makes sense as different communities would have different social communications.

The paper concludes with a note that these variable vocalizations could pose a barrier to inter-group reproduction (for genetic diversity) and should be considered in conservation.

Faith Okamoto, 5/31/2021, faith.purpleflower@gmail.com

Ocean acidification is caused by increasing CO2 levels; more CO2 in the air dissolves more into the ocean, which sets off a chain of reactions with the ultimate effect of acidifying the ocean. That's just about as bad as it sounds, and it's especially bad for corals, as it reduces calcification (which is what builds the outer structure of the corals up). It's interesting, then, to find a group of corals that seem to not be caring about such acidification.

Meet the Nikko Bay corals.

Nikko Bay is an unusual place. It's semi-closed (translation: only partially open to the ocean), has high temperatures and high CO2 levels (similar to what the rest of the world will be experiencing), but it has high levels of corals as well. It's generally escaped mass bleaching events - once when it did have bleaching nearly all the corals completely recovered. Scientists wanted to know: how are they surviving?

The answer, of course, involves measurements. Many scrupulously careful measurements, water samples and pictures and temperature readings oh my! There are a lot of technical figures and numbers, but the gist is that several different readings suggest that certain explanations (CO2 vents, e.g.) probably didn't apply, and that adaptation of the corals in this closed system was the best explanation for their survival.

Adaptation. To acidified ocean water.

In other words, the Holy Grail of what corals need to survive in the future.

To confirm this, some corals were exchanged between the bay and a reference site with similar coral community structure. The ones brought into the bay suffered from the conditions, while those taken out did not. This suggests that something internal to the Nikko Bay corals themselves was responsible for their survival.

While these results are very promising, the researchers caution that to truly show adaptation, genetic analyses must be run on the bay corals and compared to similar outside species. They suggest that such studies are run, and remind their readers that their results may be misleading due to various other environmental factors that could not be controlled for.

Faith Okamoto, 5/16/2021, faith.purpleflower@gmail.com

Sea urchins often form groups in the wild. (Yes, sea urchins can move.) This is called aggregation, and is of scientific interest as a very large/dense aggregation is dangerous to the environment. Food leads to aggregation, and many sea urchins close together destructively over-graze the area. Despite much research into individual sea urchin behaviors, and documentation of aggregation, interaction between sea urchins remains an area in need of more investigation.

Scientists, being scientists, decided to investigate. Three different densities, roughly corresponding to "not dense at all", "medium dense", and "very dense", were tested, with sea urchins placed so as to not initially touch. Food cues (powdered kelp) were added to the tank after some time. The researchers took detailed images throughout the experiment.

When the sea urchins encountered conspecifics (science-y way of saying "each other"), that physical contact had "negative effects" on their speed (science-y way of saying "they slowed down"). In general they dispersed in random disparate directions, except in the high-density group. The large aggregation of sea urchins, combined with their slowed movement when they touched each other, simply prevented many urchins from leaving.

All urchins slowed down in the presence of food cues, consistent with field ("in the wild") observations that sea urchins spent more time in high-density patches of food. However, evenly distributed food did not drive the expected aggregations, suggesting that in controlled lab conditions were unable to replicate whatever causes food-based aggregation in the field.

The scientists urge not releasing large concentrations of sea urchins in the same area when repopulating an area, as they will be unable to disperse properly. Food cues further slowed down a group's ability to spread out, so urchins should also not be released into a food-dense area.

Faith Okamoto, 5/2/2021, faith.purpleflower@gmail.com

nPCBs are bad. The technical name is "polychlorinated biphenyls", or you can just trust me that it is "bad chemical thingy". Humans (you guessed it) are polluting the environment with them, and despite bans, levels determined to be dangerous to ecological and human health still exist. Everywhere. It's a problem.

Typical research into PCBs focuses on the "big 'uns" - dolphins, killer whales, other top-of-the-food-chain predators. These animals can build up large quantities of PCBs through tropic interactions, or a fancy science way of saying "eating other stuff". It's well established that even small concentrations of PCBs in low-level organisms can become magnified up the food web. This is known as bioaccumulation. However, this means we are less knowledgeable about non-tropic interactions that lead to bioaccumulation. Here researchers looked into how mussels contribute to PCB spread, and how it affected two local species of crab: marsh and fiddler.

They chose a convenient saltmarsh, transplanted some organisms, then built a bunch of cages. No, really, cages. This allowed separate but close areas for more fine-grained data. They regularly took samples and density measurements for the organisms of interest and their food sources.

Mussels interact with the surrounding sediment to "engineer" it. Within the 5 months that the study ran, 100% of mussel areas had PCBs shoot up to dangerous levels, while only 30% of non-mussel areas did. Marsh crabs (only in mussel-ed cages), which bury near mussel mounds, had an increase in PCB concentration that could not be explained by what they ate - for one thing, their food wasn't as contaminated, and for another, it was contaminated with a different type of PCB. Therefore gill-based non-tropic interactions seem a likely path for bioaccumulation in marsh crabs. Fiddler crabs, which do not bury near mussel mounds, showed no similar increase only when mussels were present.

The researchers conclude that non-tropic interactions are demonstrably a non-negligible component of PCB bioaccumulation, and urge more research into the phenomenon.

Faith Okamoto, 4/25/2021, faith.purpleflower@gmail.com

Marine ecology likes dividing oceans into distinct regions with different ecologies. The surface, for example, will have much different characteristics from the bottom. However, it is difficult to model these ecoregions properly. There a few different types of models - those that look at species alone, those that look at ecology alone, those that look at both, and those that look at connections between areas as well. The first three methods are flawed as they do not consider movements between areas; e.g. larvae shrimp that are buffeted by ocean currents.

The researchers here sought to create a comprehensive model of the fourth type, which took into account connections between areas, each area's ecological factors, taxa (species that are present), etc. This model, δ-MAPS, is noteworthy for featuring sea surface temperature measurements. Such measurements are useful because they are so easy to take (satellite pictures) and are useful for predicting currents and other ecological factors in the ocean. Changes in sea-surface temperature are also a major hallmark of climate change.

The model was tested on data from the Mediterranean Sea from 1987-2017. It performed well on short-term and long-term changes in ecological regions. Due to the ease of gathering data the scientists suggest their model be extended and applied to other areas.

The demonstrated connections between regions were discussed in the paper, as well as the mathematical equations and considerations behind the models. But I'm not reproducing that here. Trust me, it's way too complicated :)

Sonnet Xu, 4/11/2021, sonnet.xu@gmail.com

Kidneys are a very important part of our body that we use on a daily basis, but our kidneys have very limited healing properties, making kidney diseases a huge problem. For this reason, getting diseased or injured kidneys to heal faster and work more efficiently and effectively is a major goal. Fish kidneys have a unique ability of having a huge regenerative capacity which makes them great models to study due to their regenerative capabilities. A fish's kidney is set up differently than that of a human kidney with a human’s kidneys being two beans shaped organs below the rib cage on either sides of the body. A fish’s kidney, however, is a flattened structure pushed up against the dorsal inner body wall. There are two main forms of regeneration: Tubular and Neonephrogenesis. A fish's kidney deploys a two phase regeneration process where in the first phase they undergo a tubular regeneration to repopulate cells like how humans also regenerate kidneys. The second phase is what really sets them apart, with them having the ability to regenerate the lost nephrons, which allows them to have a bigger potential for ongoing nephrogenesis in adult fishes than humans. This allows them to continually generate more and more nephrons, increasing nephrogenesis ability after an injury. This is due to an aggregate during kidney generation that leads to a rise of nephrons allowing fish to have a bigger potential for regeneration.

Faith Okamoto, 4/10/2021, faith.purpleflower@gmail.com

Here, researchers set out to answer the ultimate question - who's feeding on who? They constructed a food web (remember food webs from elementary school?) for the Santa Barbara Channel. This food web was intended to address some problems with the existing food webs of the environment, as well as be useful to future scientists.

What were the problems with existing food webs? The main thing (as the title here suggests) is that they failed to account for parasites. Parasites are notoriously difficult to factor in properly, as their interactions with hosts are hard to enumerate comprehensively. Since this a large and diverse area, some previous food webs had tried to simplify by combining whole groups of species into a single "node" of the food web; this is clearly not ideal, as even if most of that group fulfills the same ecological role not all will.

How did they make sure their web was useful? Each "node" was exhaustively checked over and a "confidence" level added as metadata (extra data attached to the main data). The researchers were most confident that a species existed in their area of interest if they saw it with their own two eyes during research dives. Then second-most confident if this species was documented in certain databases as being in this area. And so forth. This was repeated for all "links", or "who-eats-who" relationships between species.

How did they find information about nodes and links? Dives were conducted to collect data and samples; these samples were taken back to the lab and autopsied to look for what they had eaten and if they had parasites. Databases and Google Scholar were searched using standardized keywords. In an attempt to reduce "false negatives" of not finding a parasite in a certain species by bad luck, they also calculated probabilities of such false negatives with information on the parasite and the host.

This information about the food web structure will be useful to future studies and general understanding of this area and similar ecosystems.

Sonnet Xu, 4/8/2021, sonnet.xu@gmail.com

Marine biology has been extensively researched for the last several decades as a possible replacement of novel biologically active compounds, and extensive research has been conducted on lectins. Lectins that are derived from marine organisms are very structurally diverse and also different from those identified from terrestrial organisms. Marine lectins appear to be particularly useful in some biological applications. They seem to induce negligible immunogenicity because they have a relatively small size, being more stable due to their extensive disulfide bridge formation, and have a high specificity for complex glyco-conjugates and carbohydrates instead of simple sugars. It is obvious that many of these lectins have not yet been fully researched and studied when compared with lectins derived from terrestrial organisms. Marine lectins can be used to design and develop new potentially useful therapeutic agents. Lectins have helped in lots of medicinal research like the development of different antiviral drugs, fungi removal, recognition of different bacteria, helping identify different tumor cells, anti-inflammatory activity testing, helping to heal cutaneous wounds, being able to inhibit development of malaria, smart drug delivery, and therapeutic agents. Now, many investigators are looking at lectin to develop antimicrobials, antitumor and antiviral agents. The number of lectins being isolated continues to grow and their popularity also grows because of their and applications.

Maggie Zhang, 4/4/2021, maggiejyzhang@gmail.com

Australian marine scientists have recently conducted a study on green turtles in hopes to discover the areas where green turtles forage, or in other words, where green turtles find food. The motive behind this study, according to Dr. Luciana Ferriera, “was to provide knowledge to help reduce the species’ potential interactions with human activities in the resource rich areas of Australia’s northwest” [1]. To achieve their goal, the scientists used satellites to track over 100 green turtles. The data from the satellites indicated that the majority of tracked green turtles either migrated to Pilbara, a dry region in Australia, or Kimberley, an Australian savanna known for its uninhabited coastlines. Furthermore, only 2% of tracked green turtles migrated to international waters, migrating as far as Indonesia. On the other hand, 14% of the turtles simply stayed in their original nests. Considering that green turtles are near the brink of extinction [2], the outcome of this study will aid in the protection of green turtles, and serve as the first step in reducing the turtles’ extinction risk.

Sonnet Xu, 4/1/2021, sonnet.xu@gmail.com

Biodegrading plastics promises to be an eco-friendly way to recycle the plastics in our oceans. PET is a plastic commonly used in water bottles and textiles, and although there are methods for recycling PET, a large amount still ends up in our oceans. In 2016, scientists isolated a bacteria that has the ability to break down PET as the only source used for growth. This bacteria Ideonella sakaiensis expresses an enzyme that breaks down PET into monomers called PETase. This could help us reduce the amount of pollution in our oceans. Using Phaeodactylum tricornutum (a marine diatom) as a chassis, they were able to make a microbial cell factory that produces an engineered version of PETase into a culture medium. Degradation experiments using culture supernatants at 30 °C showed that PETase allowed activity against PET and the copolymer polyethylene terephthalate glycol (also known as PETG) with an 80 times higher turnover of low crystallinity PETG as compared to bottle PET. This allowed them to find a biological decomposition of PET and PETG in saltwater using a eukaryotic microalga model instead of a bacterium model. Through the synthetic biology in the diatom P. tricornutum, we could turn it into a great chassis for biological PET degradation. In the future, the diatom P. tricornutum holds great potential in biotechnology applications of PET degradation.

Derek Song, 3/28/2021, derekderksong@gmail.com

Invasive Species: An invasive species can be any kind of living organism that is not native to an ecosystem and causes harm.

Bivalve: any of a class (Bivalvia synonym Pelecypoda) of typically marine mollusks (such as clams, oysters, or scallops) that have a 2-valved hinged shell, are usually filter feeders, and lack a distinct head

Researchers Lise-Marie Pigneur, Elodie Falisse, Kathleen Roland, and Etienne Everbecq at the University of Liege, and the University of Namur in 2013 published the study “Impact of invasive Asian clams, Corbicula spp., on a large river ecosystem. The objective of this study was to verify the hypothesis that in the River Meuse, a decline of Chlorophyll a, due to the presence of the invasive Corbicula species of bivalve. Chlorophyll a is the main pigment responsible for photosynthesis, or how plants produce and plankton food. The effect of the invasive clams were studied using data on clam density, water quality data , and a simulation model. Data was collected at 7 different sites. From 2003, a decrease in phytoplankton was observed at most sites, with decline stronger from 2004-2005. Chlorophyll a concentrations in sections of the river were compared to data from a simulation of the river without Corbicula. The most impacted areas of the river had the highest Corbicula density. The filter feeding of the invasive species caused a maximum of 70% biomass loss, and a 61% loss of phytoplankton, compared to the simulation. The decrease of Corbicula also indirectly resulted in a 75% loss of zooplankton due to the loss of phytoplankton. However other variables in the river have remained stable, except for water clarity, which is directly related to phytoplankton count. The data gathered in this study can be used to further understand the impact of invasive bivalves worldwide.

Faith Okamoto, 3/28/2021, faith.purpleflower@gmail.com

Science has established relationships between "stuff happening in the environment" and "animals reacting to that stuff". However, there is an inherent lag time between something happening and any reaction to it. This study attempted to quantify the lag time between wind-driven upwelling and gathering of blue whales.

Upwelling is a phenomenon driven by winds, in which nutrient-rich deep-ocean water "upwells" to the surface. As might be expected, this creates a flurry of activity in the newly nutrient-dense area. It is known that blue whales will migrate to areas of upwelling to eat the abundant krill.

The researchers started off with calibrations. First they established that strong winds (the kind they care about) were basically guaranteed to be westerly. Then they set up sound-detectors to scan for the frequency of blue whale calls.

"Wind events" were defined as 2 or more days of strong wind, as measured by a local weather station. Satellites (yes, satellites) scanned large areas of cooler water (since deep-ocean water is cool) to find upwellings. Since the temperature contrast was more easily seen during spring and summer, the study restricted itself to observing those months.

With all that set up, the experiment was wonderfully simple. Watch for wind. Check if wind led to upwelling. Listen for whales. (Locals also reported whale sightings to help.) They found that the lag between wind and whales was about 2 weeks, though significantly shorter if the wind was unusually strong or blew for a longer time.

The scientists emphasize the important of factoring lag time into ecology models, and also that their study method is broadly applicable to measuring all other sorts of environment-reaction lag times.

Sabrina Palma, 3/24/2021, sapalma90@gmail.com

The world is in a constantly changing status: every day, new discoveries are done and new methods are improved, but our garbage's fate continues being a problem. We know that “everything goes to the ocean,” and this is valid to our trash and their compounds too. Aiming to verify the presence of organic substances hard to degrade called Persistent Organic Pollutants (or simply POPs), in truly deep regions (which have more than 2000m of depth), researchers investigated until where there's some anthropogenic influence over the ocean. This way, they looked for two POPs commonly used: Polychlorinated Biphenyls (PCBs, used as dielectric fluid) and Polybrominated Diphenyl Ethers (PBDEs, used as flame retardant) in endemic crustaceans lipids present in the Mariana Trench (in the North Pacific) and Kermadec Trench (in the South Pacific). In the first, the species chosen was Hirondellea gigas, and in the second, were Hirondellea dubia and Bathycallisoma schellenbergi–all belonging to the order Amphipoda, characterized by tiny crustaceans without carapace. The study showed that all individuals were contaminated with some POPs concentration. In Mariana Trench was found the major concentration of PCBs, and in the Kermadec Trench, the major concentration of PBDEs. Even in polluted areas, there isn’t that kind of POPs concentration, what’s very terrifying. The source of all this contamination in Mariana maybe is the proximity to industrial areas and the North Pacific Subtropical Gyre action–a mechanism formed by currents and the Earth movement–well known for uniting the floating garbage. Another explanation for these results maybe is the association of these substances with sediments (particles, as thin sand) or even with animal remains, in the way that the organisms eat them (yes, some species eat debris). Even if more studies with a physiological approach are needed, the fact that human influence has reached the deepest waters is already terrifying.

Matthew Zoerb, 3/21/2021, matthew.zoerb@asdnh.org

Though the dangers of rising carbon dioxide levels have been emphasized heavily to the public, the process of ocean acidification is less discussed. It is a of side-effect to increased atmospheric emissions. This increase translates into chemical reactions in the ocean. These reactions decrease the ocean's pH, making it more acidic.

Ocean acidification causes a broad array of harmful effects for marine life. Notably, coral reefs are predicted to become less biodiverse, experience slower growth, and be weakened structurally, as a direct result of the changing ocean chemistry caused by ocean acidification. Because ocean acidification did not catch the attention of the scientific community until the beginning of the 21st century, long-term research projects are just now reaching maturity and providing important insights to the issue.

A 10-year-long data collection project recently concluded and released its findings on ocean acidification's progress in the Australian Great Barrier reef. Two different monitoring stations located in different areas of the Great Barrier Reef measured similarly that levels of carbon dioxide in the water have steadily increased at a rate of 2.00 µatm/year, closely mirroring the increase in atmospheric carbon dioxide.

The levels of carbon dioxide measured in this study surpassed even the highest levels present in the 1960s. In addition, these results show that the surrounding seafloor does not provide a buffer to the effects of ocean acidification, as was previously hoped, making the situation even more dire. An immediate reduction of carbon emissions is needed to protect the coral reefs and the tremendously important ecosystems that reside within them.

Faith Okamoto, 3/21/2021, faith.purpleflower@gmail.com

In the ocean, bioluminescence (glowing) is a way for fish to communicate. This is especially important when fish form schools, as they must stay close enough together to be safe, without bunching up needlessly. This study looked at how A. katoptron (a flashlight fish) reacted to light-based stimulation.

First, they made a fish dummy out of silicon. This was placed in the middle of a tank along with a real fish. The tank had an exit area available. A. katoptron behavior was observed in the presence or absence of blinking light from the dummy, and different frequencies and intensities of blinking were also measured. More frequent and intense blinking led to the fish moving closer to the dummy.

Researchers also looked at if the fish could "follow" a light, and essential tool for schooling. Moving a blinking artificial light around the edges of a circular tank did indeed induce "follow"-ing behavior. At higher speed the fish were unable to keep up with the light as much, and as such their following behavior was hurt.

The researchers also observed fish in their natural habitat. For example, they flashed red light at fish in a cave environment, and observed avoidance behavior - the fish moved away from the light and bunched together, as if there was some danger.

The main finding from the paper was that the frequency and intensity of blinking was used as a signal of "nearest-neighbor distance"; or how far away a fish's nearest school-mate was. This is important information for school cohesion and school safety. It allows the fish in a school to coordinate positions with each other. The authors urge more research into exactly how this communication works, especially with field experiments outside the carefully controlled laboratory environment.

Rachel Chubb, 3/17/2021, s29003803@stu.palmbeachschools.org

It’s common knowledge that sea turtle populations are decreasing rapidly. Though this loss is most often attributed to such factors as climate change, poaching, and fishery bycatch, the truth is that there is much research to be done. One especially mysterious topic is the period of a sea turtle’s life between hatching and maturation, in which the turtle is classified as a “hatchling”. This is the period in which a sea turtle is most vulnerable, still learning how to catch prey while migrating across the vast ocean. To find out more about these “lost years”, researchers, via mini acoustic tags, tracked 43 Atlantic leatherback turtle hatchlings as they traveled off the coasts of Costa Rica and beyond.

All the hatchlings under observation were released into the ocean one week after hatching. Each was tagged with a Vemco V5-180 kHz acoustic transmitter tag, technology that allowed the research team to track the hatchlings’ locations from sunrise to sunset for three weeks. During this time period, daily tides, ocean currents, and the hatchlings’ speeds were also recorded.

After data collection, the research team carefully interpreted these measurements and recordings. Their goals were to assess how much a hatchling’s migration pattern is affected by ocean currents, to calculate the average speed of a leatherback turtle hatchling, and to predict future hatchling migration patterns and risks. Analysis of the hatchlings’ speeds and ocean currents suggested that hatchlings are unable to resist or overcome strong currents. This could be one reason that turtle populations are decreasing; as climate change creates stronger and more intense weather events, waves become stronger, trapping helpless hatchlings. Data also showed that the distance traveled by hatchlings depends on their ability to swim actively, as compared to drifting passively on waves. In the future, therefore, hatchlings may swim less far away from where they hatch. This could impact the fishing industry, marine ecosystems located further offshore that depend on turtles to stay balanced, and tourism rates in such habitats.

Overall, though this study closed a great chasm in marine knowledge, it didn’t solve every question. Since it only took place over a course of three weeks, the hatchlings didn’t travel the great distances that are expected. Also, because of limited tracking equipment, the diving patterns of the hatchlings could not be observed. More research must be done to more accurately predict turtle migration patterns and to truly understand what goes on during their lost years.

Faith Okamoto, 3/7/2021, faith.purpleflower@gmail.com

This will be a slightly unusual Review. I want to highlight an important part of science that isn't often reported on to the public - the gathering of raw data. Data are incredibly important for science. Carefully collected, high-quality data are necessary if analyses are to be run.

The goal of the researchers - and volunteers! - here was to create a long-term dataset for water quality in Buzzards Bay, Massachusetts . At more that 150 monitoring stations (some of which moved minor distances during the study, though that was avoided when possible), from 1992-2018, various measurements were taken on a regular basis.

The article clearly lays out the procedures under which data was gathered. On "basic" sampling days, small samples and a few tools gave measurements for temperature, salinity, dissolved oxygen content, pH, tidal direction, and Secchi depth ("depth you can see down"). The method by which each is measured is explained in detail to assure readers that the data are of high quality. On "laboratory" sampling days, small samples were collected and brought to the lab. These were analyzed to determine the levels of various chemicals, with methods as varied as filters to chemical reactions.

For more assurance of data quality, regular "field duplicates" were taken - samples from the same exact area at the same or similar time. The high levels of agreement between duplicates suggests that the collection methods and laboratory tools are reliable. Any extreme changes underwent further statistical review. This wasn't flashy "new discovery" science.

The article ends with a description of how to access the data (a Microsoft Excel spreadsheet) and a note that updated data will be released yearly for as long as there is funding. The researchers thank the government for their funding, and the volunteers for their time. They offer up their data (as long as attribution is given) for any to use, in the hopes that it can be used to further Science. For data, as I said, is a prerequisite for science.

Faith Okamoto, 2/27/2021, faith.purpleflower@gmail.com

Motorboat noise is a large component of noise pollution in the ocean. Excessive noise has been shown to have a variety of detrimental effects to fish, such as blocking their ability for sound-based communication by drowning it out. Loud noises also modify fish behaviors (e.g. mate preference).

This paper looked at the effect of motorboat noise on a population of Serranus scriba fish in an area frequented by motorboats. It tried to develop a State Space Model (SSM) which accounted for environmental states (day, night, motorboat, no motorboat) to predict the movement of fish in a set space, as well as between the states of "swimming" and "hidden". SSMs also include an error model to account for how real-life data cannot record every position and movement of fish.

The researchers first developed a basic model based on expected behavior, estimating values for all important variables. Then they turned it loose on real data. Several fish were caught and tagged, then returned to their original habitat and monitored for movement. Several sound sensors spread out among their area listened for motorboat sounds every 11 minutes.

The resultant data (where & when fish were detected) indicated that fish tended to swim during the day and hide during the night. Interestingly, the presence and absence of motorboat noise didn't appear to have an effect. The researchers cautioned that absence of evidence (that motorboat noise affects fish) is not evidence of absence. These particular fish may be used to motorboat noise, or perhaps overall noise pollution is a better explanation than only motorboat noise, or perhaps changes other than swimming -> hidden occurred in the fish.

The study did demonstrate that this kind of model is a useful one for modeling fish movements, and that while individual fish showed variations in their "home" area, such an area was on average smaller than previously reported.

Faith Okamoto, 2/14/2021, faith.purpleflower@gmail.com

There are some nutrients which are essential to animal and plant life. For phytoplankton, the need for iron (Fe) has been thoroughly studied. What has been looked at less is the need for manganese (Mn), an important mineral. Here researchers looked at the effects of low Mn and low iron in several areas.

The Drake Passage is naturally low in Mn compared to the wider ocean, due to several natural processes that remove Mn quite efficiently. Here, if Mn was indeed a limiting nutrient, it would be the main limiting factor and not Fe. To test the effects of removing nutrient deficiencies, the researchers essentially dumped minerals into the water and then later measured if this had any effect. This was done with both Mn and Fe, and in several different areas.

As expected, whenever a limiting nutrient was supplied the phytoplankton populations increased. In most areas only Fe was found to be limiting, while in Drake Passage Mn was the most limiting, but more Fe was helpful once Mn was addressed.

Several other chemicals were also affected by the influx of Fe and/or Mn. One especially important ratio the article touched on was silicic acid: nitrate. This ration increased when Fe limitation was addressed (due to less silicic acid being used by plankton) but decreased when Mn, or Mn&Fe, were (and the reasons are not entirely clear for this). These differences will have to be addressed by future models of marine chemistry. If the Southern Ocean (where Drake Passage is) continues to have low Mn levels, the its silicic acid:nitrate ratio will continue to be higher. They urge more study into how manganese affects marine life and chemistry.

Faith Okamoto, 2/1/2021, faith.purpleflower@gmail.com

Marine Protected Areas are established to prevent fishing, to protect critical habitat needed to ensure the survival of a species. Yet by preventing fishing they can help fishing, though a process called "spillover". Populations rise in the protected area (since they aren't being deleted by fishing) and some will migrate out due to density pressures. So protected mobile species will, inevitably, spillover into the nearby fisheries as good catch.

It is known that, for fisheries that were previously unsustainable, establishing protected areas helps in the long run. Forcing the fishery to allow some catch to live and reproduce is beneficial to prevent catastrophic overfishing.

This study looked at newly established protected areas nearby already sustainable fisheries, to see if even this would be helpful. The answer: Yes! Here the protected areas were for spiny lobsters. As expected, lobster populations increased within the protected areas, mainly from the cessation of fishing. This was determined by a "lobster census" where divers took visual estimates of lobster population and size.

Lobster catches from nearby fishing areas increased by ~225%, while analogous fishing areas which did not have protected areas nearby only increased by ~19%. This, despite a decrease in area to fish - and because catch efficiency increased dramatically. Greater efficiency is quite useful for the fisheries!

Hence, the authors conclude that marine protected areas are beneficial even when fisheries are already using sustainable practices. They urge an expansion of marine protected areas, and more research into whether networks of marine protected areas have a synergistic effect.

Faith Okamoto, 1/24/2021, faith.purpleflower@gmail.com

There are a lot of reasons why nuclear war would be a Very Bad Thing. This study looked at the effects of such a war, specifically as they pertained to ocean-driven weather patterns. Their model examined chemistry in the atmosphere, and how it would affect sunlight, temperature, rain, and other climate factors.

An El Niño like response was expected, as the increased dust and other particles in the air would be analogous to a volcanic eruption. What was surprising was the length of the response. The researchers' models found that the El Niño like temperature and precipitation (or rain) patters would persist for years and years on end. Their models found no way to reduce the effects of a "Nuclear Niño" besides simply removing all the gases from the atmosphere - a tall task if the world is dealing with nuclear fallout.

The Nuclear Niño would not simply last for longer than a regular El Niño, but would affect a wider area in a more dramatic way. Lower temperatures would be observed due to less sunlight getting through. Less sunlight has a whole host of other effects, however, such as less primary productivity (life) due to less energy input.

To summarize: nuclear war could cause a long, dramatic Nuclear Niño with lowered temperatures, rain the moves regions (flooding some and giving others droughts), and decreased sea and land life. The researchers note that their work adds to the list of reasons why Nuclear War Is Bad, and urge for it to not occur.

Faith Okamoto, 1/10/2021, faith.purpleflower@gmail.com

Let's start with a definition! Primary productivity is a measure of how much inorganic energy (sunlight, minerals) is converted to organic material (plants, animals) - most notably during photosynthesis. More primary productivity means that an ecosystem is taking in more energy, and can sustain more organisms.

Many, many factors affect primary productivity. One that hasn't been considered much is the influx of nutrients from rivers and coastal erosion. This especially matters for the Arctic Ocean, which has a great number of rivers that end in it, and many quickly-eroding coasts that used to be permafrost.

Researchers built a model to observe how nutrients (mostly nitrogen) from rivers and erosion affect the Arctic's primary productivity. More nutrients = more productivity, in general. Actually they built 3 models - one with both rivers and erosion, and one each with only one. The datasets available were suboptimal. Small, incomplete data was extrapolated with statistical models to give theoretical values for the whole ocean. Nevertheless, when the models ran their results were clear. Around 1/3 (28% - 51%) of primary productivity in the unusual Arctic relies on nutrient inputs from rivers and coastal erosion. Quite a large amount for a factor that's been left out of models.

They urge a re-understanding of recent changes to primary productivity, and a newfound consideration of coastal erosion and river nutrients in models. This should be able to reduce uncertainty and allow for smarter cultivation of the Arctic, both for fishing and for conservation.

Faith Okamoto, 12/6/2020, faith.purpleflower@gmail.com

Red swamp crayfish is the most widespread invasive species of crayfish, and has been spread around the world due to its economic value. Several known viral and bacterial diseases affect these crayfish. Since 2008 a phenomenon known as the "Black May" disease has started afflicting large commercial ponds of crayfish around May. Infected ponds have a 90% mortality rate. This study looked at which genes were differentially expressed, and in what direction. Crayfish exhibiting the characteristic symptoms were collected from an infected pond, and some healthy crayfish were also taken as comparison. DNA samples were taken from each group, assessed for quality, and then assembled and marked to determine what genes they came from. They found that most genes which were expressed with different levels were repressed. This was especially evident in the gills. Many genes essential to proper function of the mitochondria (and respiration/metabolism in general) were dramatically down-regulated. This is interesting because usually significantly inhibiting certain pathways will lead to low levels of ATP (the general energy molecule) and trigger apoptosis (cell death), but the "Black May" disease is quite infectious and spreads easily. Killing your host cell is not beneficial to an infectious agent. Several immune-related pathways were also significantly suppressed. These findings will help with the identification of the "Black May" disease's mechanism, and hopefully find a way to control it.

Faith Okamoto, 11/28/2020, faith.purpleflower@gmail.com

Many studies have tried and failed to establish a relationship between net primary productivity and zooplankton biomass. Here researchers used a broad data set to demonstrate that deep-sea zooplankton biomass is related to surface net primary productivity. And why do those long words matter? Well, they found that there is significant quantities of zooplankton in the deep sea, enough that there must be a lively active transport of carbon down there. This means we have a greater understanding of the global carbon cycle. The researchers then speculated on how the carbon is getting down to the deep sea. The main mechanism they found were fauna (animals) feeding in the upper, highly-productive surface sea area (this is why the surface net primary productivity is an important factor) and then moving downwards, either through being eaten or regular migration. The zooplankton themselves do not move quick enough to make a difference here. This mechanism is called "Vinogradov's ladder of migration". By moving carbon down into the deep sea, it sequesters it away from affecting climate change. To emphasize, this sequestering is directly related to the surface primary productivity of that bit of ocean. So a healthy ocean, with lots of biodiversity and no overfishing, is more effective in deep-sea carbon sequestration.

Faith Okamoto, 11/20/2020, faith.purpleflower@gmail.com

This study looked at several areas of the Mediterranean Sea - some with algae forests, and some barren - and compared them on a variety of ecosystem efficiency and biodiversity proxies. First off, barren areas have less biomass. (Yes, this is very obvious, but they pointed it out in the study so I'll do it here). They have less fish species as well. There are some more interesting results than just that, though! Barren areas have less efficient use of available carbon sources. This means that the local fauna is less able to incorporate carbon into themselves, leaving more to flow away. Algae, on the other hand, trap carbon during the process of photosynthesis. Different species were observed in the barren vs forest areas. Algae forests in general had "persistent" species. These are the species that help keep an ecosystem stable, and that are adapted to stick around in the same area for a while. Barren areas, on the other hand, were dominated by "opportunistic" species, or those that take over areas where nothing else is residing. They contribute less to the ecosystem at large, instead gobbling up resources and living space for themselves. Less efficient use of carbon resources, combined with residents that aren't adapted for long-term care of their environment, damage barren areas' ecosystems, biodiversity, and ability to heal. The properly functioning ecosystems of algae forests regulate water quality, provide sustenance, contribute to natural chemical cycling, oxygenate water, and many more services lacking when ecosystem quality degrades. And the areas that currently have algae forests could become this way if their forests die off. Therefore the scientists urge policymakers to institute protections for at-risk algae forests, and their fellow scientists to continue research along this line.

Faith Okamoto, 11/15/2020, faith.purpleflower@gmail.com

Here's something else to add to the list of reasons that warming waters are bad. Researchers studied the effects of increased-temperature water on two species of mussels. Both were more likely to release hemocytes, a kind of immune system cell, into the surrounding water, under such conditions. These cells are normally released under stress conditions and can be used to pass immunity to a certain disease between mussels in a connected community. But since they are so trusted, hemocytes can act as "trojan horses" - if they are infected, they bring that into the new mussel. After acute temperature stress bacteria in the ocean (10^5 - 10^6 per milliliter of ocean water) can take up residence in the welcoming environment of the hemocyte, and then stay there until the cell is brought back into a mussel. Researches tracked this occurrence by creating fluorescing bacteria, allowing them to distribute around some mussels, and then heat-shocking the mussels to release hemocytes. In layman's terms: they made some glowing bacteria and then gave them cells to infect. Lo and behold, bacteria infected hemocytes while they were out in the water, and then entered mussels and infected those as well. This is worrying because the constant warming of ocean waters, caused by climate change, will lead to more heat shocks such as this - and that means more infected mussels, which could ultimately destroy ecosystems. The scientists also hypothesized that the same method of exchanging hemocytes could lead to the spread of cancer, specifically leukemia, if the shared hemocytes were cancerous. So. As the first line said, add this to the list of Bad Effects of Climate Change.

Faith Okamoto, 11/8/2020, faith.purpleflower@gmail.com

A fair warning: this is a very complicated study, and I will not get into many of the details. The outline, however, is fascinating.

Global warming turns out to not be necessarily bad for fish populations. Researchers studied the ichthyolith (or fish-fossil) record, measuring tooth sizes and extrapolating population size based on their data and some simple models. By analyzing large amounts of fossils in this way, they could see how fish populations changed over time. Population size appeared to be roughly correlated with temperature for the time period of interest. This was an era of slow but significant global warming called the Early Eocene Climate Optimum (EECO). Simple trophic (food-chain) models, and the fact that no evolutionary or diversity changes were observed indicate that the changes in the fish-fossil record were not due to a change in the fish themselves, or due to lower predation, but instead due to increased fish production. By measuring the changes in the fish-fossil record, then the researchers could determine the levels of production at any time. So high temperatures are not inevitably fatal to fishes. There is a major caveat to extrapolating these results to our warming world. EECO's warming occurred on a geologic timescale - slowly, over many years, little by little. Global warming today occurs on an anthropogenic time scale, quick quick quick. The shock of temperatures rising so quickly means that animals will not have enough time to adapt to the new environment, and will likely experience adverse effects.

Faith Okamoto, 10/25/2020, faith.purpleflower@gmail.com

Part of climate change is ocean acidification. Some of the increased CO2 in the air dissolves into the ocean, where, through a series of intermediate steps, it forms carbonic acid. Most biology classes will use the decrease in carbonate ions, which many species use to form their outer shells, as a reason this phenomenon is bad. Here researchers explore the implications of ocean acidification through a much less common lens: the ability of Caribbean spiny lobsters to properly orientate themselves. These lobsters are heavily fished throughout Floridian and Caribbean oceans. They require chemical cues to determine proper places to settle. Since these cues are chemical, it stands to reason that their effectivity may be affected by the chemical makeup of the ocean. To test whether a more acidic environment would affect the lobsters, lava (pueruli) were caught in the Florida Keys area and put in tanks of either regular or extra acidity. Once the juveniles molted out they were held for some more time to become acclimated to the ambient acidity. Then they were placed in a Y-shaped choice tank, with one branch holding regular seawater and the other with a chemical cue indicating a good area for settlement. The lobsters raised in regular-acidity water overwhelmingly chose to move to the chemical-cue chamber, and they in general made that choice quickly. On the other hand, the lobsters raised in the low-pH (high acidity) water chose slowly. They fairly evenly split between cue and regular seawater. Most chose to stay in the initial chamber and not move at all. This indicates that they failed to sense and act on the chemical cue. In the wild this would be a major problem - if they cannot detect safe settlements, then they will be less likely to settle in a safe place and survive to reproduce. The rising acidity of our oceans, therefore, will affect these spiny lobsters. Currently-successful fisheries will have less lobsters to catch, as more will die due to hunger or predation without a good settlement. The authors suggest further research into related areas, such as the compounded effects of temperature and salinity in detecting chemical cues and the mechanism by which increased acidity damages the juvenile lobsters' abilities to detect chemical cues essential for survival.

Faith Okamoto, 10/19/2020, faith.purpleflower@gmail.com

10 million tons. That's the amount of plastic which enters our oceans each year. The shear amount of plastic debris has led to the formation of a new ecosystem, the "plastisphere", which has quite distinct organisms than the surrounding water. This study looked at the microorganisms present on plastic left in the ocean for short periods of time. Plastic bags were attached to supports along the coast of Israel in two nearby but ecologically different locations. After a 1-month period, they were removed for sampling along with surrounding ocean water. The microorganisms present were first imaged with a SEM microscope. Then DNA was extracted from each sample using standard techniques and cloned (multiplied) with PCR. Unlike previous studies, which had used Next-Generation Sequencing, this one used "MinION library preparation and multiplexed nanopore sequencing". That's a long and complicated way of saying they used techniques which allowed the sequencing of longer genetic barcodes, with more accuracy, which took longer than NGS. With these longer barcodes they could more confidently identify species. The desired sections of DNA were combined into consensus sequences before barcoding - this allows for any small mistakes made during PCR amplication to be removed before the all-important comparisons. The species found were a mix of those known to break down hydrocarbons, those related to such, and some seemingly random ones. The surrounding water had a much different microbiome (though some species were abundant in both areas, likely due to pollution), which supports the separation of the plasticsphere into a separate ecosystem. The authors suggest using various other specialized techniques to further image and determine the different species present in the plasticsphere and how those interact.

Faith Okamoto, 10/11/2020, faith.purpleflower@gmail.com

Coral snails are a threat to reef health. This study looked at the factors affecting the population levels of a particularly concerning one, Coralliophila abbreviata. Researchers considered three factors - whether a study site was a protected (no-fishing) area, the levels of coral cover, and the abundance of suspected snail predators. They chose 12 coral reefs (6 protected, 6 not) in the Florida Keys area. Most studies on these snails had been conducted in Pacific reefs, so a different location would allow conclusions to be compared between areas. SCUBA divers measured coral cover and recorded sightings of predators and snails at each site. They also took photographs for later analysis. This data was combined and fed into various models. The model which best explained the observed variance in snail populations (most parsimonious) was chosen for deeper analysis. Two predators' populations were strongly negatively correlated with snail populations, indicating that they perform a top-down selective pressure against these snails. The percentage of coral cover was positively correlated with the number of snails, so bottom-up selective pressure (the coral is a food source) is a factor as well. Whether the reef was in a protected area was also found to have an effect. Snail populations were lower in these areas, despite increased coral cover . This may be related to the diversity and number of snail predators that are available in the protected areas, which keep snail populations down. Such a hypothesis is supported by how snails in these areas are larger on average, likely due to selective pressure from predators against small snails. These findings stress how protecting reefs from fishing can help coral though various indirect ways that are not immediately obvious.

Faith Okamoto, 10/4/2020, faith.purpleflower@gmail.com

"Recruitment" is just a fancy way of saying how a population grows. Modeling it in fish populations is infamously difficult due to the number of factors involved. However, accurate population estimates are essential for proper fishery management. Every past model built of mackerel data has been rendered invalid due to a change in a factor not considered in the model. Here researchers do a comprehensive review of all the factors that may affect recruitment and attempt to build a better model for recruitment. Some factors considered are the condition of egg-producing females, the food supply for larvae and adults (across space and time), and the environmental conditions of the spawning area. Previous studies had only focused on the number of recruits, but more accurate predictions required considering each step of the recruitment process, from spawning to egg production to the survival of hatched larvae. These considerations, analyzed with various statistical methods, allowed the researchers to determine what parts of the recruitment process were affected by what factors. Some aspects of spawning (the peak time) were unaffected by any of the factors studied, but most others could be well correlated with certain variables. Older models were also considered, by extending them with new data, and were uniformly found to not have predictive power any longer. Some hypotheses surrounding recruitment were supported. In particular, the match-mismatch hypothesis, which states that the match (with respect to time and location) of certain factors (such as prey availability) is more important to recruitment than the simple presence of those factors. The new model presented by the researchers explains more of the variation observed in recruitment from 1982-2017. The continual deprecation of old models of recruitment has serious consequences for fishery management. Therefore the researchers propose further study of the interactions between factors and the development of better models for recruitment, and more specific, granular data collection to feed into those models.

Faith Okamoto, 9/24/2020, faith.purpleflower@gmail.com

Conservationists care about the sex ratios of sea turtle hatchlings. If there is a significant gender imbalance either way, that decreases the reproductive ability of the species as a whole. Sex is determined based on the conditions that the egg is incubated in. Higher temperatures lead to a larger proportion of females, while lower temperatures lead to a larger proportion of males. These calculations are made more complex by the relatively recent discovery that rainfall matters as well - high levels of rainfall increase the share of males relative to what would be predicated by temperature alone. The current methods of determining sex involved guessing (based on temperature and rainfall), sacrificing (killing) hatchlings for autopsy, or raising hatchlings until it is safe to do a surgery (which requires an expert) to determine sex. Here researchers have developed a blood test with 100% accuracy for hatchlings that are 2 or less days old. It tests for a hormone only present in males at that time. They tested their method with some sacrifices, some found-dead hatchlings, and some hatchlings that they raised for the surgery. Since their method is safe and quick, it can be used to more easily monitor wild turtles' sex ratio. More data, of course, helps conservation efforts and will allow smarter allocation of resources and drive decisions over when interventions are needed to preserve the reproductive ability of a given community.

Elise Vu, 8/13/2020, vufashionista03@yahoo.com

Climate change will cause the oceans to be more acidic, which could cause sharks’ skin to be damaged. Increased acidity corrodes the sharks’ denticles, which are microscopic tooth-like scales that cover their skin. This could impair their swimming. According to Lutz Auerswald at the South African government’s Department of Agriculture, Forestry and Fisheries, the oceans will become more acidic as CO2 levels in the atmosphere continue to increase, causing a larger issue for sharks in the future. Auerswald and his colleagues decided to test the effects of differing aquatic CO2 levels on 80 puffadder shysharks, a type of small cat shark that lives in shallow water, caught from a local harbor. While this species is already well-adapted to acidic water, other animals aren’t since more CO2 can enter the blood, preventing oxygen from reaching the tissues. The puffadder shyshark adjusts by making its blood more alkaline. The team placed the sharks into tanks with either a pH of 8 (current global level of oceans and seas) or 7.3 (which is more acidic). After nine weeks in the more acidic environment, the sharks could still use the same tactics to keep their blood more alkaline, but their denticles were negatively impacted. The water with a pH of 7.3 was enough to dissolve some of the mineral that the scales are made of. Although oceans aren’t predicted to drop to a pH of 7.3 until the year 2300, making its habitat near the western and southern coasts of South Africa makes this species more susceptible to acidic waters than other species. Also, since shark teeth are made of the same material as their denticles, this corrosion could affect the shark’s feeding. Auerswald says that denticles are found on all sharks, so other species will probably be affected as well. Furthermore, we can try to reduce CO2 emissions by reducing fossil fuel usage and energy use in general as well as carpooling with others when traveling somewhere.

Faith Okamoto, 8/11/2020, faith.purpleflower@gmail.com

Scientists created a model to study the effects of internal tides on reef temperature. Current models tend to cover large areas, and therefore fail to simulate small-scale processes that affect temperatures, such as said internal tides. Climate change continues to raise ocean temperatures, and higher temperatures can induce coral bleaching. Bleached corals recover slowly, if at all, and the species which depended on corals lose their homes in the meantime. Internal tides may help prevent this from happening. Cooler water, drawn from lower in the ocean, can reduce the ambient temperature of coral reefs from what would normally be predicted by a simple measure of surface temperature. This "flushing" with cool water occurs on a regular basis. The model showed this effect to be in full force for certain pockets of reefs. Deeper corals naturally were the coolest, but the specific structure of the reef and seafloor around it had a significant impact on whether any tides/cooling effect was observed. With lower temperatures, bleaching may be delayed or even prevented. This phenomenon is of great interest to those who study the effects of climate change on coral reefs. Further study is needed to address other possible processes which could deposit cool deep-ocean water in reef areas. A more accurate model which can predict coral areas naturally protected against bleaching would allow environmentalists to focus their efforts on more at-risk reefs.

Faith Okamoto, 7/27/2020, faith.purpleflower@gmail.com

Researchers quantified the amount of artificial light penetrating a coastal body of water near a decent-sized city which primarily used LEDs. They found that in much of their survey area, enough light hit the sea surface, middle, and floor to be biologically detrimental. They used GPS and time-stamped radiance (light) detectors across the study area. After adjusting for light from the sky and the inherent light-bending effects of water, the researchers when able to come up with confident estimates of the amount of artificial light reaching the sea. The GPS and time-stamps were necessary to quantify across the study area (closer/further from the city, for example) and across tidal shifts. Previous studies had established that (above a certain amount) exposure to artificial light sources disrupts the normal functioning of a wide range of sea life. As more people move to the coasts in search of stabler climates or new opportunities, this overabundance of light will grow and do more, possibly irreparable damage to coastal marine ecosystems. They urge further study into the biological effects of artificial light.

Evelyn Chan, 6/15/2020, evelynchan444@gmail.com

The article "Seasonal Dietary Shifts Enhance Parasite Transmission to Lake Salmonids During Ice Cover" describes a study done to examine the changes in the relationship between fish in subarctic lakes and their intestinal parasite over the seasons. More specifically, scientists sampled Arctic charr and brown trout in Lake Takvatn, located in northern Norway, from June 2017 to May 2018. Throughout this time, they collected the stomach contents of the sampled fish and recorded its fullness. The stomach contents were then searched for parasites and prey remains. An analysis of the data found that there were significant differences in the general trend of the prevalence of parasites over the seasons depending on the fish species and the parasite species. Some parasites were more prevalent in early winter while others peaked in late winter. Some species of parasite didn't vary in their prevalence throughout the season in Arctic charr but changed greatly in brown trout. Some were only found in one species of fish. Additionally, parasite diversity varied in both Arctic charr and brown trout depending on the season, although the maximum and minimum parasite diversity differed between the two species. After analyzing the data, the scientists concluded that the differences between the two fish species were mainly due to a diet difference. Arctic charr fed more on amphipods than brown trout, resulting in the species possessing a greater number of amphipod-transmitted parasites. Brown trout, on the other hand, had a diet mainly consisting of other fish. Thus, most of the parasites in the consumed fish were transferred to brown trouts. As winter approached and prey availability decreased, both fish experienced dietary shifts at different times, which then affected the prevalence of parasites in their stomachs.

Ella Crotty, 6/12/2020, eleanor.crotty@gmail.com

Scientists studied reef fish living in the Red Sea and the connected Gulf of Aden to learn about the the genetic variation of these fish populations and how it is affected by both modern and historical events. Two of the fish species studied are widespread throughout the Pacific and Indian Oceans, and the other eight are endemic (unique) to the area of the study. The study area is known for rapid changes in temperature, nutrient availability, and other factors that occur over short geographical distances and time periods, so there are several different environments for fish to adapt to. Additionally, the Red Sea has historically experienced periods of isolation from the Gulf of Aden caused by by low sea levels, which could allow two distinct populations of a species to form. These factors are likely to cause genetic variation within the study area due to natural selection. To gauge genetic differences within the populations, scientists studied single nucleotide polymorphisms, which are mutations that occur when a single letter of a DNA sequence changes, to determine how different the genomes of fish at various study sites were. The endemic species studied, found only in the study area, did not show significant genetic differences between populations, but the study did find genetic differences between the Red Sea populations and the Gulf of Aden populations in the widespread species. The study also found that these genetic differences probably reflect historical events such as the isolation of the Red Sea during glacial periods, not modern factors such as seasonal monsoons. Modern differences in selective pressures such as nutrients and temperature over short geographical distances and seasons do not seem to affect this genetic variation, possibly because all of the fish studied have larval stages that can move fairly long distances before settling down, which allows the populations to mix fairly well when the Red Sea and the Gulf of Aden are connected by water.

Elise Vu, 6/10/2020, vufashionista03@yahoo.com

Brittlestars are marine animals that resemble starfish and may see without eyes by changing the color of their bodies. They have photoreceptors (sensory cells that respond to light falling on it) along their bodies, but it’s unclear how they work. At the University of Oxford, Lauren Sumner-Rooney and her colleagues examined two closely related species of brittlestars: Ophiocoma wendtii (can position itself towards light) and O. pumila (can’t position itself towards light). Sumner-Rooney wanted to find out whether these animals could determine the contrast of a scene, rather than differentiate between light and dark. The researchers placed individuals from the two species in a 60-centimeter-diameter cylindrical tank. They colored a narrow band of the tank’s wall black with a white border, and left the rest of the tank’s wall grey. Since the black and white bands were so close to one another, the light reflected off them collided to create a light intensity identical to that of the grey parts of the wall. Therefore, an animal that can simply sense light wouldn’t be able to identify the black band. While O. wendtii did recognize the black band and crawl towards it to seek shelter, O. pumila didn’t. The reason why is that unlike O. wendtii, O. pumila doesn’t change color. Using microscopic observations and RNA sequencing (a technique that can examine the quantity and sequences of RNA in a sample), the researchers speculate that in light, the animal’s pigment-containing cells constrict the photoreceptors, which means that they can only receive light from one direction. This provides the brittlestars more detailed information about the contrast of their surroundings. Furthermore, this information could help explain how other related marine animals, such as sea urchins, are also able to see without eyes.

Wanyi Zhu, 6/8/2020, wanyi.zhu.666@gmail.com.

Corals bleach when temperatures rise, even by a few degrees, and they expel their zooxanthellae, or the symbiotic algae that provide corals with nutrients from photosynthesis in return for a protected environment to occupy. Ocean temperatures have risen due to the absorption of CO₂ from human activities, causing coral bleaching at an alarming rate. With their zooxanthellae gone, corals lack energy and are subject to stress and death. A study funded by CSIRO created 10 strains of heat resistant zooxanthellae by subjecting a culture of the microalgae to heat and selecting the most resistant samples into subcultures and applying further temperature increases to them [1]. This is a process of artificial selection, where pressure selection produced zooxanthellae strains with the desired trait: heat resistance. The resulting strains were given temperature treatments to confirm their resistance and subsequently introduced to cultivated corals to establish a symbiotic relationship. The heat-evolved strains were indeed more heat resistant compared to the wild-type strains, shown through measuring the relative electron transport rate in photosystem II, leading to the conclusion that photosynthesis was unaffected by high temperatures. Gene expression of the heat-resistant zooxanthellae was assessed through RNA-seq and the researchers found significant differences in gene regulation between wild-type and heat-resistant strains. Thus, the four years spent on this study paid off well, giving promising results for coral reef restoration, although further testing is needed before the evolved zooxanthellae are introduced to coral ecosystems.

Ella Crotty, 6/7/2020, eleanor.crotty@gmail.com.

This scientific study, done in rivers in Japan, found that diadromous (spending some of their life in freshwater and some in saltwater) species of eels are good "surrogate species," meaning that focusing conservation efforts on them will help other species living in their habitats, as well. This is for several reasons: the eels are widely distributed, so preserving their habitat will preserve the habitats of other animals; the eels are at the top of the food chain and eat diverse prey, so in order to preserve them, many other species lower in the food chain must be preserved; like other species, eel populations decrease when rivers are less connected due to dams and similar structures, so they can be used to assess how much damage dams are doing to river ecosystems; and eels are economically and culturally important to many countries, so they can act as a "flagship" species and be used to gain support and funding for conservation efforts.

Faith Okamoto, 6/8/2020, faith.purpleflower@gmail.com

Researchers completed a proof-of-concept study of coral jewelry identification through DNA analysis. Using minimal-damage methods to extract a small sample from various coral jewelry pieces, they tested different DNA extraction methods to find one that yielded the highest-quality DNA. From these samples they were able to determine with confidence the genus, or sometimes even species, used in the jewelry. No previous techniques have been able to identify species with confidence due to similarities in morphology (shape, color, etc.) between species. It is important to identify the type of coral in jewelry because some species are protected/endangered. With this now-proved DNA fingerprinting method, the corals used in jewelry can be easily and carefully monitored by conservationists.

Faith Okamoto, 6/2/2020, faith.purpleflower@gmail.com

Researchers identified a previously-unknown forest of rare black corals, which was also functioning as a breeding ground for many endangered species. Out of 68 distinct species identified, 36 are under conservation efforts. The forest was found through computer modeling of currents used to identify areas with the right conditions for forest growth, followed by checking these areas with ROV (underwater camera drones). Though the forest is mostly within a currently protected area, part is not, and fishing gear was found throughout the study site. The authors urge stronger anti-fishing protections over the whole area. However, they acknowledge that some of the species which breed in this coral forest are of great use commercially (e.g. squids, tuna, lobsters). Therefore their proposed solution is to extend the protected area's borders and enforce a ban on destructive fishing practices. They also call for further study and sampling of the forest and its inhabitants to further understand how it came to be.

Wanyi Zhu, 5/31/2020, wanyi.zhu.666@gmail.com

“Spiny Lobster Sounds Can Be Detectable Over Kilometres Underwater” by Youenn Jézéquel, Laurent Chauvaud, and Julien Bonnel was published on May 21, 2020 [1]. It describes a study of European spiny lobsters and the noises, antennal rasps, that they make by rubbing their antennae. It is thought that European spiny lobsters produce these sounds to communicate with each other [2], and Jézéquel and coauthors found that the lobsters' sounds can be detected by a hydrophone up to 3 kilometers away. To conduct this study, the researchers captured lobsters and placed hydrophones at increasing distances relative to each lobster and sounds were recorded. They extracted antennal rasps using software and performed sound analysis using pressure, frequency, and amplitude to quantify the detection ranges of the lobster noises. Although it is uncertain whether lobsters can hear each other this far away, conservationists can use this discovery in acoustic monitoring, which uses hydrophones to monitor populations and diversity [3]. Considering that they are a vulnerable species, this discovery has significant applications in conservation.