The Effects of Harmful Algal Blooms On Early Life Stages of Estuarine Forage Fish

Harmful algal blooms (HABs) caused by the dinoflagellate, Cochlodinium polykrikoides, have increased in geographic extent, frequency, and duration in many coastal areas worldwide. These blooms have negatively impacted many coastal fisheries, causing mass mortalities to both wild and farmed fish. While these mortalities have been well documented for juvenile and adult fish, the potential impacts to early life stages (i.e. embryos and eleutheroembryos) have not been explored. The potential toxicity of HABs on early life stages could significantly affect recruitment in coastal fish populations. To address this critical research gap, we conducted a series of toxicity experiments using clonal cultures of C. polykrikoides and early life stages of three forage fish species (Menidia menidia, Menidia beryllina, and Cyprinodon variegatus), all common in Northeast U.S. estuaries. We present the impacts of C. polykrikoides on embryo survival and hatching success as well as the survival of newly hatched eleutheroembryos. This research provides the first evidence of toxicity by C. polykrikoides to early life stage fish and advances our understanding of the potential ecosystem impacts of this HAB.