Month: December 2023

"Seasonal dynamics of the introduced sponge Hymeniacidon perlevis in the Elkhorn Slough, California, USA"

A Thesis Defense by Jackson Hoeke

Invertebrate Ecology Lab

Zoom | Live-Stream | December 15th, 2023 at 12:00 pm PDT

Abstract

Hymeniacidon perlevis is a cosmopolitan non-native sponge with a seasonal life cycle that has been introduced to the Elkhorn Slough in central California, USA. This study investigated seasonal and interannual dynamics of H. perlevis in Elkhorn Slough estuary, explored correlations between sponge cover and environmental conditions, and estimated how the potential scale of change H. perlevis has on its environment could vary across its seasonal life cycle. Successful recruitment is currently restricted to the upper estuary and while it varies annually, the frequency and density of sponge recruits have generally increased over time from 2007 to 2023. Prior observations have recorded seasonal patterns in other populations, and data from this study in Elkhorn Slough demonstrates a seasonal pattern variation with sponge cover peaking in October and declining to a minimum from March to May. Time-lagged Spearman-ranked cross-correlations suggest that sponge cover is correlated with increased temperature and lower dissolved oxygen at all sites, with a lag of 2-4 months. Precipitation from severe storms in 2023 also coincided with declines in sponge cover. Over the course of a year, the estimated rate of water filtered by H. perlevis and biomass accumulated are greatest in fall-corresponding with peak cover, and weakest to nonexistent in the spring. Understanding the seasonal and interannual dynamics of this population can inform future approaches to manage or mitigate its ecological impacts.

Bio

Jackson graduated from the University of Oregon in 2020 with a B.S. in Marine Biology. During that time, he studied at the Oregon Institute of Marine Biology and conducted a survey of native and introduced hydroids in Coos Bay, Oregon. Jackson is fascinated by the ever more frequent introductions of marine invertebrate species around the globe and their growing impact on the communities they establish themselves in. His current project focuses on the seasonal drivers and impacts of the introduced sponge Hymeniacion perlevis in the Elkhorn Slough next to MLML. During his free time, he can often be found reading, hiking, listening to music, or painting marine life.

"Into the Deep: Impacts of Natural and Artificial Substrates in the Deep Sea"

A Thesis Defense by Sydney Mcdermott

Invertebrate Ecology Lab

Zoom | Live-Stream | December 13th, 2023 at 10:00 am PDT

Abstract

With increasing maritime activities, man-made structures such as oil platforms, wind farms, and lost shipping containers are becoming ubiquitous in the oceans. These structures serve as substrates for marine organisms. There is evidence that unique communities develop on some man-made structures; however, the effects of substrate type vary, and are often confounded with geography and depth. Man-made objects lost in shallow water have a better chance of being retrieved than those in the deep sea, resulting in the deep sea becoming a semi-permanent repository. We studied invertebrate communities on a lost shipping container found at 1.3 km depth and deployed experimental substrates at 200 m depth to assess whether colonization and succession differ between natural and artificial substrates in the deep sea. The community on the lost container changed over time, becoming more similar to the communities on naturally occurring substrate in the Monterey Bay Submarine canyon with dominance by echinoderms, cnidarians, poriferans, and small mollusks. Communities on the experimental artificial substrates were similar to those found on experimental natural substrates, with no significant difference in diversity, richness, or evenness based on substrate type. There was a significant difference across all experimental substrates over time, indicating that the substrates may have undergone successional changes at similar rates with a major shift after 5 years. Lost objects may serve as substrates for communities mostly similar to those that form on naturally occurring hard substrates, making anthropogenic pollutants a potential subject of future monitoring efforts.

Bio

Sydney received her B.S. in marine science from the University of Maine in 2020 before attending Moss Landing Marine Laboratories. She has worked on a variety of projects across different marine habitats, from studying the microbiome of an east coast intertidal alga, to monitoring harmful algal blooms in the Pacific Northwest, to investigating the changes in sea sponge populations in the Bering Sea over the past 5 million years. Her research at MLML under the guidance of Dr. Amanda Kahn focuses on the impact of lost anthropogenic objects in the deep sea, specifically lost shipping containers. Sydney also began a PhD in ecology and evolution at the University of Louisiana at Lafayette in the fall of 2023.