The bay scallop Argopecten irradians has been an important species economically in New York since the mid 1800’s, but has gone through some drastic population fluctuations, with the population and fishery impacted by eelgrass wasting disease, harmful algal blooms and more recently an apicomplexan parasite known as Bay Scallop Marosporida (BSM). Since 2019, the bay scallop population in New York has experienced mass summer mortality events, ranging from 90-99% reduction in adult scallop biomass. Along with being highly seasonal, these mortality events have been linked to increased prevalence and intensity of BSM infections.
To examine the impact of temperature on disease development and scallop survival, two experiments were designed. In the first experiment, scallops were maintained in a flow through system at ambient seawater temperature or adjusted to mimic past temperature (-3℃ below ambient) and future temperature conditions (+3℃ above ambient). Disease development was monitored every two weeks by quantifying BSM in scallop tissues. In the second experiment, scallops were maintained in a flow through system in ambient seawater temperature or adjusted to mimic future temperatures as well as a heat wave scenario. All scallops were initially acclimated at 20℃, then temperatures were altered over the next 26 days to implement the different temperature regimes. Samples were taken after the peak temperatures were reached for the different treatments including, 25℃, 28℃ and 30℃. In addition, water and biodeposits were also collected in both experiments to quantify parasite release into the surrounding environment.
In both experiments, disease development and BSM quantification in scallop tissues, biodeposits and water were evaluated by histology, fresh kidney smears and qPCR. Data analysis is ongoing and anticipated results are expected to help understand disease development and BSM dynamics in a warming ocean.