Graduate Seminar Series 2020-2021

October 12, 2021

Using Acoustic Imagery to Estimate the Abundance of Green Sturgeon in the Sacramento River

Nicolas Coleman

University of Maryland Center for Environmental Science Institute of Marine and Environmental Technology

The southern distinct population segment (sDPS) of green sturgeon (Acipenser medirostris) that spawn in the Sacramento River are currently listed as “Threatened” under the Endanger Species Act (ESA). The greatest threats to this population are habitat impediments (dams), habitat degradation, and habitat loss which have occurred consistently since the 1950s due to water diversion efforts. Since the sDPS of green sturgeon have been listed as “Threatened” in 2006, a substantial amount of research and conservation has been conducted to understand this population’s habitat use and monitor population abundance. The objective of this study was to identify annual fluctuations in spawning run size and how such fluctuations correlate with environmental variables (i.e. temperature and flow). Additionally, this study attempted to delineate patterns in habitat use for spawning run individuals. Dual-frequency Identification Sonar (DIDSON), a type of acoustic camera, was used to detect the presence of green sturgeon in the Sacramento River during mobile surveys conducted in May/June from 2010 to 2020. The video collected from these surveys was used to count individual sturgeon at sampled transects which were then used to calculate annual estimates of abundance for spawning run sturgeon in the Sacramento River. Annual estimates of abundance were used to identify correlations with temperature and flow, identify annual fluctuations in spawning run size, and assess patterns in habitat use. The results from this study found that April flow was the strongest environmental variable correlated with annual spawning run size. Four “hot spots” that consistently supported above average abundances of green sturgeon were also identified 

May 3, 2021

Evaluating Physiological and Immune Responses of Tanner Crab (Chionoecetes bairdi) to Hematodinium sp. Infection.

Shanelle Haughton
University of Maryland Eastern Shore

Hematodinium sp. is a genus of parasitic dinoflagellates that can cause Bitter Crab Disease/Bitter Crab Syndrome (BCD/BCS), in the commercially important crustaceans, southern Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio). Tanner crab and snow crab are sold collectively as snow crabs, generating over $55 million in 2016. There are high rates of Hematodinium sp. infection in Tanner crabs native to the Bering Sea and Southeast Alaska, which can result in unmarketable crab meat and high mortalities thus causing significant losses to commercial fisheries. Based upon observed changes in biochemical composition, Hematodinium sp. may affect regulation of metabolic gene expression in infected crabs. This study will explore this effect, in addition to the regulation of genes involved in the immune response in Tanner crabs. The effect of climate change on host Tanner crab immune function, and susceptibility to disease, is also currently unknown. This study provides an opportunity to assess these parameters, and provide baseline information for assessment of the health of this fishery.

An Ecosystem-Based Modeling Approach Towards the Development of a Predator-Prey Growth Model for Bluefish, Striped Bass, and Menhaden.

Cristin Mayes
University of Miami – RSMAS

Assessment of commercial fishery stocks benefit largely from using ecosystem-based approaches, which provide a more holistic picture of fisheries by allowing for more accurate characterizations of species interactions and seasonal fluctuations in environmental conditions. For this project, single-species delay-difference models for bluefish, striped bass, and menhaden are developed to approximate their yearly population. Empirical weight-at-age data from 1985-2012 are used to derive the parameters and estimates necessary for such models. Total biomass for each species were estimated over this 12-year period to conduct a pre-assessment to serve as the foundation for each single-species delay-difference model constructed. Each single-species model is then used to produce a line-of-best-fit for the biomass data derived in the pre-assessment. These include a retroactive, equilibrium, and local stability analyses; all of which are conducive for fisheries stock assessments. Lastly, these models are used to conduct a 20-year forecast for each species. This research therefore serves as the foundation for two distinct multi-species models, as well as the basis for more complex methods aimed at defining ecosystem-level patterns for these commercially viable Mid-Atlantic

February 1, 2021

Utilization Pacific Lamprey anatomical structures as records of age, natal origin, & trophic patterns.

Keala Pelekai
Oregon State University

The Pacific Lamprey (Entosphenus tridentatus) is an anadromous species native to the North Pacific Ocean and its adjacent freshwater tributaries.In that last 50 years, Pacific Lamprey have experienced declines in abundance throughout the Columbia River Basin, USA. More information on the biology and ecology of this species is needed for conservation and management.Anatomical hard structures (otoliths, scales, fin rays) have been widely used in fisheries science for biological inference. However, Pacific Lamprey is a cartilaginous fish that lacks the common hard structures used in teleosts to elucidate age and life history patterns. Statoliths, analogous to otoliths in function, are apatite concretions found in lamprey auditory capsules. Statoliths have potential for aging and elemental analysis but need to be assessed to determine if the structure grows bands reflective of age and environmental chemistry. Eye lenses are another structure with potential for trace element and stable isotope analyses but remain relatively unexplored for lamprey. The goal of this project is to broaden our understanding of lamprey by evaluating the efficacy of different structures for determining age, natal origin, and trophic history patterns. These objectives will be achieved by evaluating lamprey statoliths and eye lenses collected from known age and origin specimens.

Analysis of Microplastic Abundance in Organisms with Varying Foraging Strategies in Waters Near Savannah, GA, USA.

Savannah Gieger
Savannah State University

Factors such as wave energy, biofouling, currents, and variable densities of seawater and plastics have the potential to affect where microplastics concentrate in the aquatic environment. Particulate plastics can occur in both pelagic and benthic environments. The purpose of this study was to analyze microplastic abundance within organisms of differing foraging strategies. A benthic feeding species, spot Leiostomus xanthurus, and a pelagic feeding species, brief squid Lolliguncula brevis, were collected from trawls in Wassaw Sound and the Wilmington River near Savannah, GA, USA in May 2019. Twenty whole brief squid and 20 spot gastrointestinal tracts and gills were individually digested in 10% potassium hydroxide, then vacuum filtered, and analyzed under a stereomicroscope. The number of microplastics per individual were spatially interpolated using the ArcGIS-based Inverse Distance Weighted (IDW) method from all trawl locations to investigate fine-scale differences. Spot from Wassaw Sound contained 7.1 ± 6.9 microplastic particles and 5.5 ± 6.2 from the Wilmington River. Brief squid from Wassaw Sound contained 7.4 ± 4.5 microplastic particles and 5.0 ± 1.0 from the Wilmington River. The range of microplastic particle abundance per sample was 0-33 for all samples examined. IDW results indicate that organisms from Wassaw Sound had more microplastic particles per sample than organisms from the Wilmington River. Elevated microplastic counts in organisms from Wassaw Sound compared to the Wilmington River may be due to varied exposure of fish from Wassaw Sound to multiple anthropogenically impacted rivers that connect to the sound. These results are critical in understanding how to manage Georgia coastal waters, specifically how to begin to mitigate particulate plastics in the environment.

December 7, 2020

Genetic approaches for monitoring the effects of climate change on Leopard Seals (Hydrurga leptonyx) in the Antarctic Peninsula.

Arona Bender
Hampton University

In the Western Antarctic Peninsula (WAP), global climate change is dramatically affecting marine living resources. In particular, krill abundance has decreased >80% in the past three decades, leading to cascading effects in the Antarctic food web. Strikingly, over this timeframe, leopard seal (Hydruga leptonyx) numbers have increased during the austral summers. Leopard seals are generalists: they feed on krill, fish, and cephalopods but also consume penguins and seals, leading to a significant reduction of mesopredator colonies. Remarkably, data on leopard seal abundance is lacking; surveys are costly and hold a high degree of uncertainty, so no data on population trends are available. Here, we propose to estimate the leopard seal population effective population size (Ne) and historical demography using mtDNA sequences. We are making use of tissue samples (n = 117) from Southwest Fisheries Science Center in La Jolla, CA, collected for over a decade by the US Antarctic Marine Living Resources Program. This research will provide valuable data on leopard seals that can serve as a foundation for scientists to determine future scenarios in one of the most rapidly warming areas around the globe. 

Ecological & Social Predictors of Salmon Habitat Restoration Effort in Puget Sound.

Brittany King1 and Robby Fonner2
1Oregon State University, 2NOAA Northwest Fisheries Science Center

Over the past 20 years, thousands of salmon restoration projects have occurred in the Pacific Northwest, with the ecological goal of protecting and recovering threatened and endangered salmon species. However, studies in other regions of the United States have found that in addition to the ecological drivers of restoration projects, there are also social factors influencing restoration, that are often overlooked. To better understand these dynamics, our project investigates the ecological and social influences on the distribution of salmon habitat restoration efforts in the Puget Sound region of Washington state. We seek to answer the following research question: How does the regional distribution and cost of completed salmon restoration projects correlate with biological, physical, and human community characteristics? Using Puget Sound salmon restoration projects data obtained for the NOAA managed Pacific Northwest Salmon Habitat Project Database, this project seeks to gain an understanding of whether salmon restoration  efforts in the Puget Sound tends to flow towards certain types of communities, after controlling for biological and physical factors, and the potential equity and environmental justice implications.

NOAA Living Marine Resources Cooperative Science Center
University of Maryland Eastern Shore (Lead Institution)
(410) 651-7870
Award numbers: FY 2016 Award #NA16SEC4810007 
Funding Agency: NOAA Educational Partnership Program with Minority-Serving Institutions (EPP/MSI)

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