Estuarine and coastal transformation is as old as civilization yet has dramatically accelerated over the past 150 to 300 years. Reconstructed time lines, causes, and consequences of change in 12 once diverse and productive estuaries and coastal seas worldwide show similar patterns: Human impacts have depleted >90% of formerly important species, destroyed >65% of seagrass and wetland habitat, degraded water quality, and accelerated species invasions. Twentieth-century conservation efforts achieved partial recovery of upper trophic levels but have so far failed to restore former ecosystem structure and function. Our results provide detailed historical baselines and quantitative targets for ecosystem-based management and marine conservation.

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Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas

Invasions by non-indigenous species (NIS) are recognized as important stressors of many communities throughout the world. Here, we evaluated available data on the role of NIS in marine and estuarine communities and their interactions with other anthropogenic stressors, using an intensive analysis of the Chesapeake Bay region as a case study. First, we reviewed the reported ecological impacts of 196 species that occur in tidal waters of the bay, including species that are known invaders as well as some that are cryptogenic (i.e., of uncertain origin). Second, we compared the impacts reported in and out of the bay region for the same 54 species of plants and fish from this group that regularly occur in the region’s tidal waters. Third, we assessed the evidence for interaction in the distribution or performance of these 54 plant and fish species within the bay and other stressors. Of the 196 known and possible NIS, 39 (20%) were thought to have some significant impact on a resident population, community, habitat, or process within the bay region. However, quantitative data on impacts were found for only 12 of the 39, representing 31% of this group and 6% of all 196 species surveyed. The patterns of reported impacts in the bay for plants and fish were nearly identical: 29% were reported to have significant impacts, but quantitative impact data existed for only 7% (4/54) of these species. In contrast, 74% of the same species were reported to have significant impacts outside of the bay, and some quantitative impact data were found for 44% (24/54) of them. Although it appears that 20% of the plant and fish species in our analysis may have significant impacts in the bay region based upon impacts measured elsewhere, we suggest that studies outside the region cannot reliably predict such impacts. We surmise that quantitative impact measures for individual bays or estuaries generally exist for ,5% of the NIS present, and many of these measures are not particularly informative. Despite the increasing knowledge of marine invasions at many sites, it is evident that we understand little about the full extent and variety of the impacts they create—singly and cumulatively. Given the multiple anthropogenic stressors that overlap with NIS in estuaries, we predict NIS‐stressor interactions play an important role in the pattern and impact of invasions.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1999.44.3_part_2.0950

Non-indigenous species as stressors in estuarine and marine communities: Assessing invasion impacts and interactions

http://digital.csic.es/bitstream/10261/25111/1/10.1.1.112.5446.pdf

Perkinsosis in molluscs: A review

From its initial discovery in the Gulf of Mexico in the late 1940s until 1990,Perkinsus marinus, the parasite responsible for Dermo disease in the eastern oyster,Crassostrea virginica, was rarely found north of Chesapeake Bay. In 1990–92, an apparent range extension of the parasite led to epizootic outbreaks of the disease over a 500 km range north of Chesapeake Bay. One of the hypotheses for the range extension argues that small, undetected numbers of parasites were already present in northern oysters as the result of repeated historical introductions, and that a sharp warming trend in 1990–92 stimulated the disease outbreak. This argument was based on trends in air temperature. The present study examined this hypothesis by analysing water temperatures, rather than air temperatures, for five stations located in areas affected by the recent epizootics. At all five stations, there was a strong increasing trend in winter sea-surface temperature (SST) between 1986 and 1991. At four of the five stations, there was a smaller increasing trend in winter temperatures after 1960. There were no consistent or obvious trends in summer (August) temperatures. In Delaware Bay, which has a 40 year history of monitoring for oyster diseases, occasional findings ofP. marinusin oysters were correlated with warming episodes that were especially notable in the winter (February) record. Empirical orthogonal function (EOF) analysis showed that winter temperatures varied consistently at the stations examined and were associated with variations inP. marinusprevalence. Associations using EOF analysis with August temperatures were much weaker. The SST record is consistent with the hypothesis that increasing winter water temperatures have been important in the recent outbreak ofP. marinusepizootics in the north-eastern U.S.A.

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The Relationship Between Increasing Sea-surface Temperature and the Northward Spread of Perkinsus marinus (Dermo) Disease Epizootics in Oysters

The relationship of potential defense-related cellular and humoral activities and the susceptibility of eastern oysters Crassostrea virginica to the parasite Perkinsus marinus were examined at 10, 15, 20 and 25 \"C. Oysters were acclimated at experimental temperatures for 20 d and then challenged with R marinus. Total hemocyte counts (TC) and percentage of granulocytes (PG) 20 d after temperature acclimation were higher in oysters at high than at low acclimation temperature. Higher protein (P) and lysozyme (L) concentrations were found in oysters at 10 and 15 \"C. No significant differences in hemagglutination (H) titers due to temperature acclimation were observed. Infection prevalence 46 d after challenge by R marinus was 100, 91, 46 and 23 % respectively, for oysters at 25, 20, 15 and 10 \"C. Disease intensity increased with temperature. Oysters at higher temperatures had greater PG and TC and hemocyte phagocytic activity. No difference was found in TC and PG between control and challenged oysters within each temperature treatment. Bleeding may to some extent reduce TC and PG in oysters. P did not vary much among temperatures. No reduction of P in oysters was found due to P. marinuschallenge and infection. L tended to be higher in oysters at lower than at higher treatment temperatures. The oysters at 10 \"C had the highest L concentration and lowest P marinus infection. But, it is not known whether the high extracellular L in oysters at 10 DC is attributable to the low R marinus susceptibility in these oysters. There was no significant difference in condition index (Cl) between control and challenged oysters and between infected and uninfected oysters. However, C1 decreased with increasing temperatures. The H titers were not associated with any measured variables. The greater TC, PG, and phagocytic capability in oysters at higher temperatures did not result in fewer or less intense P marinus infections.

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Perkinsus marinus susceptibility and defense-related activities in eastern oysters Crassostrea virginica: temperature effects

PAGE INTRODUCTIONa. Studies in the Gulf of Mexicox. Discovery of Dermocystidiumn marinurm in Virginia 2 METHODS OF STUDY 2 The Thioglycollate Culture Technique 2 Rating the Intensity of Infections 3 Definitions of Terms 3 THE OCCURRENCE OF Dermocystidium marinuim IN LIVE OYSTERS 3 Seasonal Incidence of Infections 3 Intensity of Infections 5 Recapitulation ........ 6 THE OCCURRENCE OF Der-mocystidium marinumn IN GAPERS 6 Collection of Gapers 6 Seasonal Incidence ..... 6 Incidence in Gapers from Outlying Trays and Natural Habitats ..... 8 Recapitulation ........ 8 DISTRIBUTION OF Dermocystidium marinum IN CHESAPEAKE BAY 11 FUNGUS INFECTIONS IN RELATION TO AGE AND SouRCE OF OYSTEST.11 Data from Live Oysters . ..... 11 Data from Gapers ......... 12 Recapitulation. 13 EXPERIMENTAL INFECTION OF OYSTERS 14 Infection of Old Oysters ...... 14 Infection of Young Oysters I ........ 14 PAGE

/pdf/oyster-mortality-studies-in-virginia-ii-the-fungus-disease-22jbnrnxmp.pdf

Oyster Mortality Studies in Virginia. II. The Fungus Disease Caused by Dermocystidium marinum in Oysters of Chesapeake Bay

https://www.jstor.org/stable/info/1948649

Willis G. Hewatt

Papers

Oyster Mortality Studies in Virginia. II. The Fungus Disease Caused by Dermocystidium marinum in Oysters of Chesapeake Bay

Marine Ecological Studies on Santa Cruz Island, California