Rapid recovery of a fish assemblage following an ecosystem disruptive algal bloom

Abstract

Disturbance of freshwater ecosystems through cultural eutrophication has resulted in an increased global occurrence of harmful algal blooms (HABs). Ecosystem disrupting algal blooms (EDABs) are a subset of HABs that produce extensive disturbances across entire ecosystems. Prymnesium parvum is an EDAB species that has invaded freshwater systems worldwide, causing massive fish kills and other negative effects. Fish kills frequently occur during HABs and EDABs, but few studies exist of the long-term implications of these fish kills and the resilience and recovery of fish assemblages following kills. We sampled fish near- and offshore over an annual cycle encompassing a P. parvum EDAB in 2 coves (i.e., a bloom site and a reference site) of a southern Great Plains reservoir, Lake Texoma, Oklahoma–Texas (USA). Our objective was to document the extirpation and recovery of a fish assemblage in response to the disturbance of an EDAB event. Prymnesium parvum bloomed in 1 cove from mid-December 2008 until May 2009 and eliminated all fish during this period. Fish toxicity bioassays indicated no substantial differences in susceptibility among fish species to P. parvum toxins. Fish recolonized the bloom site rapidly in May 2009 after the bloom diminished. Fish assemblages were resilient to the P. parvum EDAB, and recovered to previous abundance, richness, and composition within 6 mo. Our results suggest that the reservoir-wide fish meta-assemblage enabled a rapid recovery of local fish assemblages after a spatially heterogeneous EDAB.