The Effect of the Toxic Dinoflagellate Alexandrium fundyense on the Calanoid Copepod Calanus finmarchicus

Abstract

Harmful algal blooms have represented a serious problem for local economies and public health worldwide. The propagation of toxins through the marine web chain, and the negative effect on higher consumers, has raised questions on how primary consumers, such as herbivorous zooplankton respond to toxic algae. Inshore and offshore waters of the Gulf of Maine (USA) are seasonally dominated by the toxic dinoflagellate Alexandrium fundyense, which is responsible for paralytic shellfish poisoning (PSP) in humans. The calanoid copepod Calanus finmarchicus co-occurs with A. fundyense during spring and summer blooms. High survival has been reported for this copepod exposed to the dinoflagellate, however, little is known about other effects. The goal of my dissertation work was to study the effect of A. fundyense on the fitness and physiology of C. finmarchicus in controlled laboratory experiments. Fitness was measured as survival and reproductive success. Changes in global gene expression using RNA-Seq technology were used to measure the physiological response. The results suggest that blooms of A. fundyense are an environmental challenge for C. finmarchicus with a negative effect on copepod population growth. The negative effects included a decrease in reproduction, as well as metabolic adjustments, such as a decrease in lipid biosynthesis and protein synthesis/cell growth. My results demonstrate that transcriptomics is a tool that can be used to investigate the physiological ecology of non-model species such as copepods in order to identify biological processes affected by non-optimal environmental conditions.