From Beach to Beach

— Written by Emma Saas

Rising sea levels and beach erosion create problems for important intertidal species, such as beach hoppers, normally found on sandy beaches. Their sandy environment is shrinking, and scientists are wondering how well they will find new real estate. The distribution and abundance of different each hopper species may vary among southern California shores, but one can find beach hoppers, such as Megalorchestia corniculata, on many beaches. The dispersal of beach hoppers from beach to beach may be an important factor in the distribution of the four common species.

Yachts are a little bit pricey for our tiny beach hoppers, so how can they move from one beach to the next? The answer may be drift kelp, an important resource for marine environments that is produced by off-shore kelp forests. Beach hoppers can cling to drifting kelp and perhaps use this mechanisms as a lift to new beaches. How well they can cling, however, is an important question. Ideally, beach hoppers may be able to survive rising sea levels by clinging to drift kelp after it washes onto the shore and then leave with it as it floats to its next destination. An added bonus? Kelp is also food for these traveling beach hoppers! They’re able to sustain themselves for free while traveling (personally, Delta charges me excessive amounts for the same thing), which could enhance their survival on longer trips to a new beach.

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Beach hopper climbing in Macrocystis pyrifera, otherwise known as giant
kelp, commonly found on California beaches washing in from the kelp forests

Sea level rise will lead to habitat changes and a requirement for flexibility. According to recent studies, 25% of beaches are eroding worldwide and up to 67% of beaches in southern California could disappear by the end of the century. Creatures who made their homes on sandy beaches will see a significant narrowing of their stomping ground. Their ability to disperse to and from different beaches on kelp may reflect how well they can move around once sea levels are consistently encroaching on their living space.

Finding needles in a hay stack

— Written by Maria Rivera

Collecting hundreds of kilograms of sediment samples is challenging but finding microscopic shark scales in the midst of hundreds of sand grains is another thing entirely. In the process of extracting denticles from large sediment samples, several steps such as lab processing, many gallons of acetic acid, and hundreds of hours of microscope time are required. First of all, we need to collect the samples (bulk of sediments), from a region with high and low shark abundance to be able to make comparisons. For example, with my project on a small island in the Caribbean called Curaçao, there are samples from two sites. One site has high human impacts while the other has less human impacts. A potential hypothesis might be that the more impacted site might have less sharks and therefore less denticles.

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Fig.1 shows the microscopes used in the lab when we are searching for denticles in a sample.

Once the samples are collected, we then weigh each sample in the lab. These samples are then separated into different sized fragments using sieves with various mesh sizes (2 mm, 500µm (micrometers), 250µm, 106µm, and 63µm). The denticles, which are the size of several strands of hair, are found in the 106, 250, and 500 µm fractions. The bulkiness of these samples would make it nearly impossible to pick through, like finding a needle in a hay stack, thus, we add 10% acetic acid to reduce the size of the mass significantly. This gets rid of all the carbonate (coral and shell) material, which compromises over 90% of the samples’ mass. We also have to rinse the sample with hydrogen peroxide to get rid of any excess organic material. All that is left is the non-organic and non-carbonate residue that the denticles are found in. Now it is feasible to pick through the different sized grains and identify our denticles under a microscope. Once we identify our denticles in a sample, we measure them and look at the ridges and how they are shaped. This helps us determine the type of shark form which it was shed. When we identify the denticles, we can plot our data and analyze/make inferences about how shark communities vary across different human interference sites. Going back to Curaçao, once we have all the data, we would be able to analyze what types of sharks roam each site and their relative abundance, as well as how that has changed over time. This will shed a light to how humans have impacted the coral reef shark communities in both areas.

It is important, however, to realize that a number of factors can impact the number of denticles we find in a sample. For example, denticle abundance can be affected by denticle shedding rates, transportation, and coral reef growth and sedimentation rates. In regards to shedding rates, we do not know how often sharks shed denticles or whether shedding rates differ between pelagic and demersal species, and this can impact how many denticles we find in a sample. When it comes to transportation, denticles can be transported horizontally by currents as they sink. However, our collection sites are located on very sheltered, low energy reefs, and modeling exercises have shown that sinking denticles do not travel very far. With coral growth, if a coral reef is growing at a fast rate, denticles would be deposited and then buried at a quicker rate. As a result, denticle densities per amount sediment would be lower at faster accumulating reefs. To correct for this, we date corals to determine how much time is encapsulated in each sediment sample. These are just some of the few things that we need to consider when we are analyzing denticle abundance and trying to relate that to shark abundance.

Fingerprinting the Culprit

— Written by Vivian Lee

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Figure 1. Sea star tube feet sample in 100% ethanol

What are some things that come into mind when we think of DNA fingerprinting? Perhaps, an episode of CSI or Criminal Minds about identifying a murder suspect might be the first thought that crosses our minds. Similar to finding a murder suspect, bacteria DNA fingerprinting is being studied in my lab with Dr. Nguyen to catch a possible culprit, a bacterium known as Vibrio, which may be responsible for the sudden deaths of sea stars that occurred across the West Coast in 2014. In hopes of finding the presence of Vibrio on sea stars, we will culture the bacteria on plates in different agar environments, some that are rich in nutrients more than others to grasp how this bacterium behaves in the ocean, and the effects that it harbors on sea stars in the Rocky Intertidal.

Let’s take a step back and sink ourselves into an episode of a crime investigation scene where there is a case investigator and a crime scene personnel collecting sources of evidence such as hair or blood, swabbing around the perimeter to collect any other possible articles of DNA to then have it analyzed in a lab. Likewise, I play a similar role in which I collect DNA of sea stars out in the field, to then have the DNA extracted, whereupon, an amplification is done through Polymerase Chain Reaction (PCR). Once the fragments of DNA are separated by gel electrophoresis, I observe the fragment size to

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Figure 2. Species Pisaster ochraceus found

analyze the presence of the 16s ribosomal subunit. This gene prompts the identification of a bacteria present in a bacterium swab sampled from a sea star. There are two methods in which DNA and the presence of multiple bacterial communities are collected from the stars. One, where I bargain with the sea stars as they give me a fair game of tug of war with their tube feet and when I win, in exchange I take a few tube feet back to the lab as seen in Figure 1. These organisms have the capability of regenerating their tube feet, as well as their arms, which allows the methodology of stealing their tissue quick and convenient. Because sea stars possess this trait of restoration to heal damaged tissues, questions arose when these Echinoderms began “melting”, one arm at a time when they became infected with the Sea Star Wasting Disease. Secondly, to observe which bacterial communities place sea stars under huge amounts of distress, areas where white lesions form on the body as seen in Figure 2 are swabbed, along with the exterior tissues that do not have white lesions, therefore to compare the presence of Vibrio in “healthy” and “non-healthy” sectors of the body.

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Figure 3a. Coal Oil Point Rocky Intertidal. b. Emma Saas and Vivian Lee making observations at Hazards Canyon intertidal. c. Species Pisaster ochraceus affected by SSWD

Sampling the species of Pisaster ochraceus non-local sites such as Hazards Canyon in comparison to the local intertidal at Coal Oil Point, where it has become barren of sea stars raises questions concerning to what is holding one species over another back from making a comeback to recovery. By surfacing one of many hypotheses proposed about the cause of the Sea Star Wasting Disease through observing past bacterium samples that were collected during the Sea Star Wasting Disease is currently preparing me to compare the presence of the 16s ribosomal subunit in current stars that may have survived the disease.

Operation PURFECT (Purple Urchins Routinely Feeding in Extreme Climate Temperatures) Methodology

— Written by William Dejesus

I am measuring consumption of giant kelp by purple sea urchins, Strongylocentrotus purpuratus, living in experimental temperature waters. Twelve tanks were evenly divided into two different temperature seawater tables. The ambient temperature water table will stay consistent with current water temperatures outside, usually around 16-17°C. The warm water table is kept between 21-22°C. Drippers are used at the end of the inflow tubing to ensure consistent flow rate across tanks. The warm water table system contains a reservoir bucket that is used to pump the water to each tank ensuring consistent temperatures across the tanks.

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Warm water table with inflow tubing from reservoir

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Reservoir allowing incoming seawater to warm up

Urchins in this experiment were collected from various areas around the Channel Islands. The size of the urchins was measured upon entry to the lab, where almost all fell between 4 and 6 centimeters in diameter. All urchins were given a week of acclimation to the storage table. All relevant urchins are given a 3-day temperature and starvation acclimation period before being distributed to their individual tanks for trials. Using an acclimation period minimizes the affects of prior food availability and behavioral responses to increased temperatures. The twelve urchins subject to feeding trials are given 1 pre-weighed blade of giant kelp each per trial. Only blades of kelp are being used for feeding because of urchins’ prior known preference for this part of the plant. Each trial will last approximately 3 days, with deviations accounted for in rate calculations. The trial period was determined to be long enough for significant consumption but short enough that kelp degradation was minimal. There will be two trials each week with a 24 hour “No Food” break once a week. This allows for the trials to remain structured on a weekly basis. Statistically relevant deviations between trials with and without the “No Food” break before feeding will be acknowledged if found. Any experimental urchins that yield little to no kelp consumption (>1g) will be removed from experimentation after two consecutive trials with minimal consumption. These tanks will be replaced with acclimated urchins when the next trial begins.  Consumption of kelp is measured using wet weights of the kelp before and after each trial. Each blade is spun in a salad spinner before being weighed to reduce extra water weight in a consistent fashion.

Crabs Gone Wild: A Look at the Mysterious Foraging Behavior of Rock Crabs

— Written by Gabbie Baillargeon

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Two female brown rock crabs (Cancer antennarius)

Any research involving the study of living animals is simultaneously exciting and frustrating due to the fact that lab experimentation involves manipulation of individuals who have a brain of their own and don’t always want to cooperate nicely.  Although the general goal of my research project is to study the foraging behavior of brown rock crabs on California mussels, the specifics within addressing this research query have shifted in response to my preliminary observations of crab behavior.  Through this research project, I have come to find that doing science is a much more elaborate, drawn out, and unpredictable process of discovery than the simple flowchart of the scientific process in my high school biology book.

In order to start experimenting on the rock crabs, all of the crabs must undergo a set acclimation phase where they are allowed to get settled into their new, luxury tank habitat.  Following acclimation, the plan was to start all of the crabs in individual trials where both crab density, number of crabs per tank, and prey density, number of mussels per tank, would be systematically manipulated.  Simply, this experiment involves changing two variables: food availability and crab predator abundance, with the goal being to measure how the crabs respond to these changes by counting the number of mussels consumed and documenting behavior during feeding. All was going according to

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A gravid female yellow rock crab

plan for the first few weeks as crabs came into the lab they were placed in tanks, fed, and played nice with one another. However, due to little previous research published or documented observations available for reference, I had the privilege of witnessing first hand a wide array of surprising crab behaviors before the experiment even began.  For those of you who, like myself, were blissfully unaware of rock crabs’ night time job as a ninja, I am here to tell you that they are exceptionally stealthy little beasts who are capable of destroying every plastic tank barrier I repair. Without the tank barrier in place properly, crabs could move freely between the tanks which makes it impossible to accurately measure which crabs consumed which mussels – a vital aspect of data collection.  Along the way, a few crabs were lost in the battle for scientific understanding as some crab fights would end in death for the loser.  There was even an instance of crab suicide, where the crab simply found a way to escape its tank and met its unfortunate end drowning in the open air.   Additionally, many of the female crabs collected started to become gravid, or possessing eggs, during the acclimation period. To avoid any bias in the study, all females who were not gravid were going to be used in the experiment.

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Measuring and labelling a new batch of rock crabs to prepare for running foraging trials

A series of small pre-experiment foraging trials were conducted to get a sense of how the crabs interact with each other, how many mussels they consume, and how they utilize tank space.  The most surprising find of this small study was that groups of female crabs consumed many more mussels than groups of male crabs, indicating that there is a difference in their foraging behavior.  Given this new information, along with the predicament of females become pregnant, the experiment was reconsidered to answer a slightly different question within the same frame of investigating the interface of rock crab foraging and human impact on their populations.  My experimental design shifted to reflect this new path of investigation, as the study now tested only males. To accommodate a shortened timeline and restricted tank availability, the number of prey and predator densities was altered as well.   All in all, the crabs provide a good laugh, a frustrated yell, and sometimes a proud smile along the journey of designing and running foraging trials to better understand their feeding preferences and behaviors.

 

 

Guide on How to Spawn, and Experiment on, Urchin Larvae

— Written by Carlos Estrada

Step 1: Collecting Gametes

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Left: Male L. pictus expelling sperm. Right: Female L. pictus dispensing eggs

To begin raising urchin larvae, we first have to “convince” the parents to reproduce. But instead of dimming the lights and lighting a few candles in hopes that the urchins will hit it off, we take matters into our own hands. We start by injecting 1-2mL of KCl around the mouth of the urchin, which causes them to stiffen and release their gametes. Since male and female urchins are morphologically similar, their gametes become their only differentiator. If sperm begins to flow out, the urchin is obviously male and is placed on ice to keep cool. If eggs begin to ooze, the urchin is female and is left inverted on an overfilled 50mL conical tube, where the eggs will begin to drizzle down and gather at the bottom. This process is repeated with as many urchins needed to gather one male and at least five females.

Step 2: Fertilization

Before mixing the sperm with eggs, we make sure that the sperm is healthy by checking for motility. Once motility is confirmed, we move onto the eggs by homogenizing them and check for a coefficient of variation under 10%. Doing this allows us to have a rough estimate of how many eggs we’ve collected from each female and helps calculate the volume needed to have an equal amount of eggs between all females. Next, we test fertilization using a dilute amount of sperm and eggs, looking for a >95% fertilization rate. If successful, we fertilize the entire batch and transfer the fertilized eggs into our rearing buckets at either 15°C or 20°C.

Step 3: Developmental Timeline

Checking for the developmental stage is done by taking a small, concentrated sample from the bucket every 30mins-1hr, and placing them under the microscope. Urchin developmental stages are so variable from one another, that confirming the stage can be quite easy!

Step 4: Sampling

Sampling is done through a seemingly simple, yet complex, system involving buckets, mesh, beakers, and soft-line tubing. Once the larvae are siphoned into a collection beaker and then concentrated into a 15mL conical tube, which is homogenized for an egg count.

Step 5: Thermal Tolerance, Heat Shocking, and Morphometrics

Thermal tolerance trials are conducted by transferring larvae into a heat block with a gradient of temperatures that will help determine the temperature at which L. pictus is no longer able to function. The larvae are left in the heat block for an hour and subsequently checked for mortality. Heat shock trials will be done by placing larvae into four different temperatures, allowing for one-hour recovery, and then flash freezing for future extraction of the hsp70 heat shock protein. Morphometrics will be used to take pictures of the larvae to measure sizes and to determine whether increased temperatures influenced development. Once the trials are finished, down the drain they go!

 

The Attack of Vibrio and the Plummeting Deaths of Sea Stars

— Written by Vivian Lee

A keystone species, one that is largely depended upon by other species, acts as a fundamental instrument for balancing an ecosystem at a constant equilibrium. Thus, when a keystone species population declines or has an absence in an ecosystem, the consequences are detrimental. Recently, the Rocky Intertidal Community of the West Coast has been facing consequences such as overpopulation since the sea star wasting epidemic. In 2013, a mysterious disease spread from Washington State to as far North as Alaska and as far South as  Mexico, sweeping across the coast and taking away many sea stars species in its path.

As white lesions form on the body, the disease takes away each arm at a time, and clinging onto what becomes the last of themselves, the sea stars waste away until only a sheer outline of ossicles remain ghostly on the rocks of the intertidal. The wasting disease leaves sea stars hopeless as the progression to death can take less than a few days, leaving them unable to salvage themselves; causing populations to plummet to the verge of local extinction. Amongst the many species, Pisaster ochraceus was among those attacked the hardest by the disease,producing questions and possible hypothesis not only for the Pisaster ochraceus but the rest of the sea stars. Being one of the biggest marine epizootic outbreaks that occurred, questions are still on the rise, parameters have been continuously observed as the cause of the disease are countless.

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Figure 1: Photos above display three different species of sea stars. 1a displays  two Pisaster ochraceus sea stars (orange and brown) and Pisaster brevispinus (pink). 1b is a closer view of the brown Pisaster ochraceus. 1c. Sea star species known as Pisaster giganteus

Is it the rise of seawater temperature along the west coast? Could the El Nino event have played a part in intensifying the pathology in infected stars from certain sites compared to others? Perhaps the salinity of the water? Has something changed in these Echinoderms’ diets? Finding a concluding answer has been as difficult as finding a needle in a hay stack; however, an explanation of the disease has been monitored. Vibrio, a bacteria found in sea water and some marine organisms such as crab and eel can affect both humans and other marine organisms. Vibrio was found on many sea stars that were collected for observation. This bacterium may have opened the doors that weaken the sea star, causing the white lesions to form and eventually leading to death. Site by site along the Southern California Coast, multiple bacterial swab samples of sea stars were collected during the time span during and after the outbreak. Whether the stars showed phenotypic/ physical attributes of sickness or not, samples were taken to observe the presence of the bacteria.

Previously, a collaborative team from Dr.Hofmann’s lab at UC Santa Barbara collected swab samples of Pisaster ochraceus from sites in Southern California ranging from Lompoc to San Diego, including the Channel Islands. This summer, a continuation of detecting the presence of the bacteria will be studied. Through this, we anticipate grasping a better understanding of the biodiversity of the bacterial community associated with sea stars from  samples collected during and after the outbreak. We hope to find current sea stars in sites locally around Santa Barbara as well to understand and monitor the differences compared to when the outbreak occurred.

Ara’s Fishy Adventures

— Written by Ara Yazaryan

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Counting dorsal rays of a rockfish

As a research assistant in the Caselle laboratory, my entire experience revolves around fish. My day starts at 9 o’clock, when I report to the lab and march over to the microscope for duty. One of the ongoing projects in the Caselle lab which I have the good fortune to partake in is the SMURF monitoring program at Santa Cruz island. The SMURF discussed here, contrary to the little blue people that may come to mind, is a large black “cushion” of intertwined black fencing material. SMURF stands for Standard Monitoring Unity for the Recruitment of Fishes. This large object is meant to mimic kelp structure, and gives planktonic fish larvae a place to settle and grow. Every two weeks, these SMURFs are netted and the fish are collected and frozen for later study. And this is where my abilities with a microscope come in! One of my primary laboratory responsibilities is to count and sort the SMURF fishes into each respective species. Though some species, such as Cabezon (Scorpaenichthys marmoratus) are instantly recognizable, other families of fish, such as juvenile rockfish (Sebastes) and the Clinids require a closer look. In order to separate them into the respective species, all rockfish must be observed under a dissecting microscope in order to count their fin rays. Each species of rockfish has a unique combination of dorsal and anal fin rays, serving to identify these individuals when they are young and have not yet developed their respective mature morphological features. I examine these fish one-by-one and sort them, and then place them into a final freezer storage.

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Otoliths – note the concentric ring structure

When my eyes need a break from the microscope, I move on to fish dissections. Another of my laboratory responsibilities is extracting the otoliths from fish heads. After opening the brain case, these “ear-stones” are extracted and saved for storage. Eventually, the otoliths will be polished and observed under a microscope. As a fish mature, information about what it eats, rates of growth, and potential environmental stressors is stored inside their otoliths. All this important information can be gleaned by extracting and observing the otoliths.

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Large Male Sheephead (Semicossyphus pulcher) collected at Anacapa Island

The third project that I have just begun to work with is the monitoring of California Sheephead (Semicossyphus pulcher) stomach contents between sites at Anacapa Island. Fish were captured by spear or hook-and-line (much to my inner angler’s delight) and their stomach contents will be examined to determine how MPAs affect their feeding habits and population levels. The overarching goal of these three projects, and the information I aspire most to learn about, is how California fish communities are responding to Global Change. Fishing, climate-change, Ocean warming and acidification, and pollution all have the potential to degrade our rich fish stocks. By studying and monitoring these fish, I hope to gain a better understanding of California’s complex marine ecosystems. In particular, I want to more thoroughly understand how MPAs conserve fish populations, and correspondingly alter dietary structures. I will use the Sheephead (As Dr. Caselle has made very clear, there is no “s” in the middle) as a model organism for this experimentation. I seek to answer the question: Does dietary composition of Sheephead change inside and outside of Marine Protected Areas? Using observation of stomach contents coupled with statistical quantification, I set out to answer this question over the course of my REU program. Though only two weeks have gone by, I feel as if I have gained a year’s worth of scientific immersion. Between lab work, field research, and peer camaraderie, I have gained a much clearer understanding of what research in the marine science field consists of. I look forward to what is to come, and am excited to examine many more fish in the upcoming weeks at UCSB.

What does a changing climate mean for Phytoplankton and what does this mean for our planet?

— Written by Ean Eberhard

The microscopic marine algae known as Phytoplankton are incredibly important to our planet. Although minuet in size these organisms have an immense amount of responsibility within both aquatic and terrestrial ecosystems.

Phytoplankton are primary producers, the foundation of the marine food web, feeding everything from zooplankton to massive whales. As a primary producer these phytoplankton create the foundation of the aquatic food web and thus bare the weight of the rest of the aquatic food web. In other words, the fluctuation in phytoplankton abundance could mean a collapse in the web.  Phytoplankton are not only a source of food but are also a large contributor to the biological carbon pump, responsible for most of the carbon dioxide transfer from the atmosphere to the ocean. For this reason, changes in the growth of phytoplankton could have a great effect on atmospheric concentrations of carbon dioxide. Phytoplankton can also be detrimental. When nutrients levels are high, phytoplankton can grow out of control, creating algal blooms which produce extremely toxic compounds with many harmful effects.   There is no doubt that the balance in phytoplankton abundance is crucial to all life. Unfortunately, phytoplankton are experiencing more stress due to a changing climate.

For the next seven weeks I will be studying the photochemistry of phytoplankton in response to three different stressors. This experiment will be a multifactorial design that will give a more realistic look into how the stress of a changing climate is much more complex than rising temperatures. These three stressors include variances in light intensity, temperature, and CO2 levels. Each of these stressors correspond to variances in the phytoplankton’s environment due to the change in climate. I will dive deeper into the response of these phytoplankton by measuring cell abundance, cell efficiency, Dissolved Inorganic Carbon and pH. This experiment will give us an insight into just how exactly phytoplankton may respond to a changing world and the findings may provide an insight into how the effects on phytoplankton could have a ripple effect on all other life.

Will one of Japan’s most famous delicacies survive a changing climate?

— Written by Will Dejesus

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Purple urchin feeding on giant kelp

Sea urchin is a famous Japanese delicacy used in sushi, called uni. The gonads, or sex organs, is the part of the urchin that is actually eaten. It is high in protein and contains omega-3 fatty acids, which can help lower blood pressure. Sea Urchins can be found along the West coast from Baja to Seattle. Sea Urchin harvesting along the coast of California has become one of the highest valued fisheries in the area. Almost 75% of the urchins caught along the California coast are sent to Japan, where they import over 250 million dollars worth every year.

Not only are sea urchins a relevant part of the food and fishing industry, but they also play a critical role in the kelp forest communities, as their preferred food source is giant kelp. With few native predators, sea urchins have the power to decimate kelp forests, which are already struggling with changes in ocean chemistry. Areas where sea urchin population has sky rocketed, kelp density has been nearly wiped out in a short period of time. From ocean to table, sea urchins play an important role in coastal communities on land and below the surface.

I am interested in taking a closer look at the feeding habits of these invertebrates given future predicted changes in ocean temperature. Their reactions to temperature changes in general and especially in feeding behavior is all of interest in this study. This will begin to paint a clearer picture of what we can expect our marine ecosystems and seafood industry to look like in the future.