Toxicity of Dinoflagellate (Gonyaulax verior) from Makassar Strait Waters on Medaka Fish (Oryzias javanicus) Embryo Development

This study investigates the toxic effects of the dinoflagellate Gonyaulax verior on the embryonic development of medaka fish (Oryzias javanicus) sourced from four distinct aquatic environments in the Makassar Strait. Given the increasing presence of harmful algal blooms in marine ecosystems, understanding the impact of toxic dinoflagellates is crucial for assessing risks to fish populations. Embryos were exposed to varying concentrations of Gonyaulax verior isolated from four locations: Jeneberang Estuary, Maros Estuary, Pangkep Estuary, and Paotere Port. The effects on embryonic mortality, morphological abnormalities, and developmental rates were systematically recorded. The findings revealed significant variations in embryonic development across locations; notably, embryos exposed to dinoflagellate toxins demonstrated increased mortality rates and higher incidences of morphological deformities compared to control groups. The data reveal a significant trend: embryos exposed to dinoflagellate cysts exhibit a higher yolk absorption rate than control groups. This trend is most pronounced in the Jeneberang Estuary, where dinoflagellate-exposed embryos demonstrate the highest recorded yolk absorption rate of 0.0031 mm³/hour, contrasted with a control rate of 0.0027 mm³/hour. The Jeneberang Estuary exhibited the highest survival rates, whereas the Maros Estuary and Pangkep Estuary showed alarming levels of toxicity, leading to substantial developmental impairments. These results underscore the ecological implications of Gonyaulax verior proliferation and highlight the need for monitoring harmful algal species in the Makassar Strait. This research contributes to understanding the impact of marine toxins on fish embryonic development. It emphasizes the need for effective management strategies to mitigate the effects of dinoflagellate blooms on local aquatic ecosystems.