REUfest

Analyzing Otoliths for hypoxia markers

Hello, my name is Branden Kohler and this fall I will be starting my senior year at Kutztown University of Pennsylvania. I am majoring in Marine Science with a focus on marine biology. This summer I am working in Dr. Ben Walther’s lab under his doctoral student John Mohan. John and I are studying the effects of hypoxic conditions on the Atlantic croaker (Micropogonias undulatus) in the Gulf of Mexico. Hypoxia, the term used to describe water conditions when very little dissolved oxygen is present in the water, is an extremely important issue that has long-reaching impacts on the gulf’s ecosystem as well as the success of the fisheries markets in the gulf and around the world. While there is data on hypoxia’s effects on marine life, there has yet to be a full-proof method in determining if a fish has been exposed to hypoxia. John and I are studying the chemical composition of the otoliths or ear stones of the fish in order to determine if they had been exposed to hypoxic conditions. Otoliths are calcified strutures that function similar to the ear bones in other animals. They are an excellent source of data because they grow in layers from birth and are not reabsorbed by the body, making them permanent records of the fish’s life-history. The process involves sectioning pieces of the otolith and chemically analyzing the otoliths via a laser to determine the elements present in the otoliths. The presence of certain elements in high quantities could indicate exposure to hypoxia. This information could help reconstruct the environmental conditions of specific habitats as well as further otolith research as a method to understand the life dynamics of fish and assist in the management of fish populations.

The Role of Olfactory Cues in the Settlement Patterns of Red Drum Larvae (Sciaenops ocellatus)

    Hi, I’m Brooke Coughlan, and I am a Senior at Worcester Polytechnic Institute in Worcester, MA. I am studying biology and biochemistry there, but have had few opportunities for marine or field work. I hope to gain a better understanding of the process of marine research, which will help me decide on a major when I attend graduate school in a few years. This summer I am excited to be wroking with Lee Fuiman and Lisa Havel at the Fisheries and Mariculture Laboratory.

     For most fish species, the larval period is the most vulnerable phase in the life cycle. Less than 0.1% of marine fish larvae survive to maturity, but it is unclear which factors contribute to the success of certain individuals over others. For many species, early larval stages inhabit pelagic waters, and then move to the benthic environment in a process known as settlement. This pelagic period is the primary opportunity for dispersal for some species. Reef fish larvae have demonstrated an active role in the settlement process by proficiently swimming and orienting themselves in the water column. These larvae respond to visual, auditory, and olfactory cues for orientation, however little is known about the settlement strategies of species that live in environments that are arguably more complex than coral reefs. In this study I used the red drum, Sciaenops ocellatus, an inhabitant of the estuarine waters of the Gulf of Mexico, to study the potential use of olfactory cues in the settlement process. In the waters surrounding Port Aransas, red drum larvae settle into seagrass beds after passing through tidal inlets during the late summer and early fall. To determine if larvae were attracted to chemicals emitted from seagrass beds, I tested their preference for different chemical signatures associated with seagrass habitats in laboratory trials using a “Y” maze. Treatments included various concentrations of dissolved lignin and tannic acid (compounds produced by seagrasses), water containing the scents of S. ocellatus predators, and as a control, artificial sea water. Research into the signals that attract larvae to seagrass settlement areas has the potential to improve management of threatened fish species as well as declining seagrass populations.

Toxicity increase due to photomodification from UVB radiation

My name is Sarah Baca and I’m currently a senior at UT El Paso. I’m majoring in Environmental Science with a biology concentration. I have been working in a lab for three years studying the toxicity of Pharmaceuticals and Personal Care Products (PPCP)on the freshwater rotifer Plationus patulus. This summer I’ll be working with Dr. Ed Buskey and Dr. Rodrigo Almeda. We’ll be studying the photoenhanced toxicity of crude oil and chemically dispersed oil to zooplankton.

Petroleum or crude oil is one of the most common pollutants released into the marine environment. Rising global energy demand has resulted in an increase in the search for and transportation of crude oil in the sea, making marine environments especially susceptible to increased risk of crude oil spills. Among the biological components of marine ecosystems, zooplankton are particularly susceptible to crude oil pollution. Zooplankton play a key role in marine food web dynamics, biogeochemical cycling and fish recruitment. Therefore, understanding the effects of crude oil on zooplankton is crucial for our understanding of the impact of oil spills on marine environments.

Many variables, including the use of chemical dispersants and environmental factors (e.g., temperature, salinity, turbulence, sunlight) may affect the toxicity of crude oil after oil spills. Treatment of oil spills frequently involves the use of chemical dispersants. Dispersants promote the removal of an oil slick from the surface waters enhancing the formation of small oil droplets. It has been suggested that the new generation of dispersants (e.g. Corexit 9500) and chemically dispersed oil are less toxic than the spilled oil alone. However, little is known about the effects of this dispersant or dispersant treated oil on zooplankton. Among the different environmental variables affecting oil toxicity, sunlight (UVB radiation) may increase the toxicity of crude oil due to the photosensitization of organisms and/or photomodification of the polycyclic aromatic hydrocarbons. However, most crude oil toxicological studies have been conducted in the laboratory under artificial light and the influence of photoenhanced toxicity (i.e., increase in the toxicity in the presence of sunlight) on the toxicity of oil spills in the ocean is poorly understood.

The main goal of this project is to investigate the influence of UVB radiation on the toxicity of crude oil and chemically dispersed crude oil to marine zooplankton. We will use representative species of target groups of zooplankton, including copepods and protozoans. Zooplankton will be incubated in quartz bottles and exposed to: 1) crude oil (1-5 μl L-1) and 2) chemically dispersed oil (1-5 μl L-1 of oil + 0.05-0.25 μl L-1 of dispersant). For each treatment, zooplankton will be exposed to 2 different light regimes: 1) the full solar radiation spectrum, 2) the full spectrum without UVB (bottles covered with Mylar-D foil). Control and experimental treatments will be run in duplicates. Bottles will be incubated on a pier in a large open/uncovered transparent acrylic container containing a plankton wheel with open-circuit seawater running through it, thus providing exposure to sunlight and in situ temperature. After 48 of exposure, mortality/swimming activity of zooplankton will estimated under the microscope.

The expected results on the influence of sunlight (UVB) on the toxicity of crude oil and chemically dispersed oil to zooplankton will be relevant for a better understanding and predicting of the impact of oil spills and the use of chemical dispersants in marine planktonic food webs.

The Role of Protists Versus Bacteria in the Decomposition of a Tetrapeptide

My name is Alyssa Riesen and I’m from Sussex, Wisconsin. I am a rising senior at the University of Wisconsin-Whitewater, currently working towards a Bachelors of Science degree. I am an Environmental Geography major with a chemistry minor. My mentor this summer at UTMSI is Dr. Zhanfei Liu. His expertise is in marine organic geochemistry. With him I look forward to studying peptide hydrolysis rates of the Ship Channel water in Port Aransas, TX.

Within the food web in the ocean is a microbial loop involving plankton, ciliate, heterotrophic nanoflagellate (HNF) / dinoflagellate, bacteria, dissolved organic matter including peptides and algae. It is traditionally thought that bacteria play the major role in the peptide hydrolysis, but recent evidence suggested that certain protists including some harmful species could hydrolyze the protein as well. The goal of my research during this summer is to quantify the roles of ciliates, HNF/ dinoflagellate and bacteria in peptide hydrolysis. Research of this topic during the summer gives me an advantage due to the potential abundance of dinoflagellate in the Ship Channel water.

This experiment will begin with the collection of water samples from the Ship Channel. Filters with different pore sizes will filter the water to obtain the necessary plankton size for result comparison. The next step is to incubate the peptide, AVFA, approximately for 65 hours, using the size-fractioned water. Throughout the 65-hour time period, there will be 8 time points where one bottle will be sacrificed for sample collection. These time points include the hours 0, 12, 24, 30, 36, 42, 48, 65. After incubation the HPLC will be used to quantify the concentration change of AVFA throughout the 65 hours in the different plankton sample types. I will be looking at the bacterial community composition (BCC), protist change, peptide change and finally, hydrolysis product (shorter peptides, amino acids, and ammonium). Fluorescence dying will also be used to count bacteria and protist cells by being stained and observed under epifluorescence microscopy.