Evaluation of the relationships between physico-chemical parameters and the abundance of spp. in blue crabs () and seawater from the Maryland Coastal Bays.

Introduction: Fluctuations in water quality characteristics influence the productivity of blue crabs (), and the risk of human exposure to pathogenic species. Thus, this study assessed the prevalence of total and pathogenic/clinical markers of and in blue crabs and seawater from the Maryland Coastal Bays (MCBs) and the correlation between levels and physicochemical parameters.

Methods: Three to five crabs and 1 L of seawater were collected monthly for 3 years (May 2018 to December 2020) from six sites within the MCBs. Hemolymph and crab tissue were extracted and pooled for each site. Extracted hemolymph, crab tissue, and seawater were analyzed for and using the Most Probable Number (MPN) and real-time PCR methods. A one-way Analysis of Variance (ANOVA), correlations, and linear models were used to analyze the data. Akaike Information Criterion (AICc) was evaluated to determine the model that provides the best fit to the data relating to concentrations and environmental factors.

Results: Results suggested that environmental factors could influence the growth of spp. Both and were more prevalent during the warmer months than colder months. was more prevalent in crab samples compared to seawater. concentrations in seawater and hemolymph were positively correlated with temperature ( = 0.0143 seawater) and pH ( = 0.006 hemolymph). A negative correlation was observed between the concentration of in whole crab (tissue) and dissolved oxygen level ( = 0.0256). The concentration of in seawater was positively correlated with temperature ( = 0.009) and negatively correlated with dissolved oxygen ( = 0.012).

Discussion: These results provide current information on the spatial and temporal distributions of spp. in the MCBs that are useful for implementing more efficient processing and handling procedures of seafood products.