Two talks at Hopkins Marine Station

Assessing shark populations, species distributions and fisheries through the four letter code!

Marine ecosystems worldwide are experiencing shifting baselines due to a combination of anthropogenic and environmental stressors. Unprecedented fishing pressures, are decimating species populations, while climate change, disease, and invasive species occurrences are contributing to shifts in species distributions.

While all of these phenomena occur concurrently there are yet to be addressed data deficiencies, which stifle our response and restrict our ability to protect the marine environment. In order to address these knowledge gaps a comprehensive, robust and expedient assessment of marine ecosystems is required to ascertain current baselines and to identify and prioritize conservation measures at an ecosystem scale. The current revolution in genomics offers a robust tool to take the pulse of the ocean, establish baselines and to inform marine conservation and management.

I will share research towards creating a ‘Genomic Seascape’, to track diversity, stability and distribution of shark populations and to serve as a forensic tool to track illegal fisheries. I will discuss, 1) the use of whole genome sequencing to build a robust framework for benchmarking population structure, stability and connectivity of reef shark populations and for tracking illegal fisheries, 2) species distribution and fisheries assessments using environmental DNA (eDNA), and 3) building genomics capacity for robust monitoring of biodiversity and fisheries to enable sustainable and effective conservation outcomes through equity and inclusion in marine conservation.

Shaili’s research focuses on conservation genomics of elasmobranchs. She is interested in building new genomic tools and capacity for oceans surveillance, biodiversity and fisheries assessments. She earned a PhD in human genetics from the University of Utah, an MS in Biochemistry and a BS in Microbiology from India.

Speaker: Shaili Johri

Thermal sensitive mechanistic models of schistosomiasis

Environmentally mediated diseases, especially those whose life cycle involves free-living phases and ectotherm hosts, like snails, are significantly influenced by temperature. An example of this is schistosomiasis, a parasitic disease of poverty that affects more than 200 million people worldwide, and results in 200,000 fatalities annually. Although several models have been constructed to investigate the relationship between temperature and schistosomiasis transmission, we still don't fully comprehend how temperature variations affect the dynamics of the disease. Based upon laboratory experiments and existing literature, we built a comprehensive, thermally sensitive mechanistic model of schistosomiasis transmission, whose demographic and epidemiological factors are recast as a function of temperature. The model was utilized to calculate the thermal optimum for the basic reproduction number R0 and the mean parasite burden. Next, the consequences of various environmental interventions that aimed to reduce transmission were evaluated on the thermal optimum. The thermal optimums separately for Schistosoma haematobium and Schistosoma mansoni have been founded. Our results: i) the thermal optimum is higher than previously estimated, and the thermal optimum for the mean parasite burden differs from the thermal optimum for the basic reproduction number R0; ii) while increasing snail mortality through molluscicides or biological control may shift the thermal optimum, this is not the case when snail abundance is governed by removing vegetation. Our analysis shows that the dynamics of schistosomiasis are highly sensitive to temperature and some control programs may change the optimum temperature for the disease transmission.

Speaker: Ibrahim Aslan, Stanford University

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