Prevalence of Microplastics in the Eastern Oyster Crassostrea virginica in the Chesapeake Bay: The Impact of Different Digestion Methods on Microplastic Properties

This study aimed to determine the microplastic prevalence in eastern oysters (C. virginica) in three sites in the Chesapeake Bay in Virginia and optimize the digestion methods. The digestion results illustrate that the lowest recovery rate and digestion recovery were related to enzymatic, enzymatic + hydrogen peroxide (H2O2), and HCl 5% treatments, while the highest digestion recovery and recovery rate were observed in H2O2 and basic (KOH) treatments. Nitric acid digestion resulted in satisfying digestion recovery (100%), while no blue polyethylene microplastics were observed due to the poor recovery rate. In addition, nitric acid altered the color, changed the Raman spectrum intensity, and melted polypropylene (PP) and polyethylene terephthalate (PET). In order to determine the number of microplastics, 144 oysters with an approximately similar size and weight from three sites, including the James River, York River, and Eastern Shore, were evaluated. Fragments were the most abundant microplastics among the different microplastics, followed by fibers and beads, in the three sites. A significantly higher number of fragments were found in the James River, probably due to the greater amount of human activities. The number of microplastics per gram of oyster tissue was higher in the James River, with 7 MPs/g tissue, than in the York River and Eastern Shore, with 6.7 and 5.6 MPs/g tissue.

Transcriptomic Response to Perkinsus marinus in Two Crassostrea Oysters Reveals Evolutionary Dynamics of Host-Parasite Interactions

Infectious disease outbreaks are causing widespread declines of marine invertebrates including corals, sea stars, shrimps, and molluscs. Dermo is a lethal infectious disease of the eastern oyster Crassostrea virginica caused by the protist Perkinsus marinus. The Pacific oyster Crassostrea gigas is resistant to Dermo due to differences in the host-parasite interaction that is not well understood. We compared transcriptomic responses to P. marinus challenge in the two oysters at early and late infection stages. Dynamic and orchestrated regulation of large sets of innate immune response genes were observed in both species with remarkably similar patterns for most orthologs, although responses in C. virginica were stronger, suggesting strong or over-reacting immune response could be a cause of host mortality. Between the two species, several key immune response gene families differed in their expansion, sequence variation and/or transcriptional response to P. marinus, reflecting evolutionary divergence in host-parasite interaction. Of note, significant upregulation of inhibitors of apoptosis (IAPs) was observed in resistant C. gigas but not in susceptible C. virginica, suggesting upregulation of IAPs is an active defense mechanism, not a passive response orchestrated by P. marinus. Compared with C. gigas, C. virginica exhibited greater expansion of toll-like receptors (TLRs) and positive selection in P. marinus responsive TLRs. The C1q domain containing proteins (C1qDCs) with the galactose-binding lectin domain that is involved in P. marinus recognition, were only present and significantly upregulated in C. virginica. These results point to previously undescribed differences in host defense genes between the two oyster species that may account for the difference in susceptibility, providing an expanded portrait of the evolutionary dynamics of host-parasite interaction in lophotrochozoans that lack adaptive immunity. Our findings suggest that C. virginica and P. marinus have a history of coevolution and the recent outbreaks may be due to increased virulence of the parasite.

The Northern Gulf of Mexico

This chapter describes the Gulf of Mexico (GOM) region and the major issues facing this marine fisheries ecosystem, and presents some summary statistics related to the 90 indicators of ecosystem-based fisheries management (EBFM) criteria. The region contains high numbers of marine species comprising commercially and recreationally important invertebrate (e.g., penaeid shrimp, blue crab, eastern oyster) and finfish (e.g., red snapper, grouper, red drum, pelagic sportfishes) fisheries, which contribute heavily to national landings and seafood supply. The northern GOM contains one of the nation’s largest marine economies (among the eight U.S. regional marine ecosystems), which is dependent on offshore mineral extractions, tourism, marine transportation, living marine resources (LMRs), and other ocean uses. The GOM provides critical social and economic benefits to the region and the nation, is a region with high numbers of managed species, yet exploitation of these resources and an increasing human population makes the GOM an area subject to significant natural and human stressors, including the highest number of hurricanes in the U.S. Atlantic region, large expanses of hypoxic bottom water, overfishing, and major oil spills like the 2010 DWH event.

The U.S. Mid-Atlantic Region

This chapter describes the Mid-Atlantic region and the major issues facing this marine fisheries ecosystem, and presents some summary statistics related to the 90 indicators of ecosystem-based fisheries management (EBFM) criteria. While containing lower numbers of managed taxa among the eight regional U.S. marine ecosystems, this region has relatively well-managed state and federal fisheries that are important both nationally and along the U.S. Atlantic coast, including Atlantic menhaden, blue crab, eastern oyster, black sea bass, summer flounder, and striped bass. The Mid-Atlantic is an environment that is subject to stressors that include habitat loss, coastal development, nutrient loading, climate-related species range shifts, hurricanes, other ocean uses, and proliferation of invasive species. Overall, EBFM progress has been made at the regional and subregional level in terms of implementing ecosystem-level planning, advancing knowledge of ecosystem principles, and in assessing risks and vulnerabilities to ecosystems through ongoing investigations into climate vulnerability and species prioritizations for stock and habitat assessments. While information has been obtained and models developed, only partial progress has been observed toward applying ecosystem-level emergent properties or reference points into management frameworks. While the Mid-Atlantic is leading in many aspects of its LMR and ecosystem-centric efforts, challenges remain toward effectively implementing additional facets of EBFM, and particularly enacting ecosystem-level control rules. This ecosystem is excelling in the areas of LMR and socioeconomic status, the quality of its governance system, and is relatively productive, as related to the determinants of successful LMR management.