Abstract
Blooms of the dinoflagellate, Cochlodinium (a.k.a.Margalefidinium) polykrikoides, have had deleterious effects on marine life across the Northern Hemisphere and, since the early 1990s, have become more frequent and widespread. While the toxic effects of C. polykrikoides have been well-described for finfish, the effects on bivalve molluscs are poorly understood, particularly in ecosystem and aquaculture settings. The purpose of this study was to characterize the comparative effects of C. polykrikoides blooms on North Atlantic bivalves and to identify the environmental factors that influence its toxic effects. The growth and survival of two age-classes (first- and second-year) of the northern quahog (Mercenaria mercenaria), the bay scallop (Argopecten irradians), and the eastern oyster (Crassostrea virginica) were quantified in surface deployments and at depth during annual bloom events in multiple locations across eastern Long Island (NY, USA), capturing a natural gradient in C. polykrikoides. In two consecutive years, scallops deployed within surface locations experienced significant mortality (75–100%) during short-term (1–2 weeks) but intense (> 1.5 × 104 cells mL−1) C. polykrikoides blooms. Conversely, scallops deployed at depth and clams and oysters deployed at either the surface or at depth were more resistant to blooms. First-year oysters and scallops that survived blooms displayed significant reductions in growth rates, while clams and older scallops and oysters did not. Results suggest that blooms of C. polykrikoides pose significant age- and species-specific threats to native and cultured bivalve shellfish and that shellfish deployed in surface waters are at greater risk during blooms than those deployed at depth.
Highlights
IntroductionCertain Harmful algal blooms (HAB) are capable of producing potent neurotoxic or gastrointestinal biotoxins that can (bio)accumulate in the tissues of exposed shellfish, and when consumed by humans can result in severe intoxication (Shumway 1990; Hégaret et al 2009) making shellfish aquaculture vulnerable to these events
Results of this study demonstrate that blooms of C. polykrikoides, in addition to laboratory-based settings (Gobler et al 2008; Tang and Gobler 2009a, 2009b), are lethal to shellfish in natural settings, posing a threat to multiple species and age-classes of bivalve molluscs
Among commercially and ecologically significant North Atlantic bivalve shellfish, bay scallops appear to be at greater risk than oysters which appear more sensitive to blooms than clams and shellfish cultured at surface locations appear more vulnerable than those deployed at depth during C. polykrikoides blooms
Summary
Certain HAB are capable of producing potent neurotoxic or gastrointestinal biotoxins that can (bio)accumulate in the tissues of exposed shellfish, and when consumed by humans can result in severe intoxication (Shumway 1990; Hégaret et al 2009) making shellfish aquaculture vulnerable to these events. As aquaculture industries continue to expand and concurrent changes in climate stimulate the growth and proliferation of certain HAB (Gobler et al 2017), identifying potential risks (i.e., vulnerable species) and mitigation strategies may limit losses.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
