Mass Mortality of Fish in Lampung Bay, Indonesia
ABSTRACT: The surface waters
in Lampung Bay appeared with dark reddish brown color from the beginning of
October until November 2012 due to a bloom, an explosion in the phytoplankton
population. This event resulted in the mass mortality of fishes that are
cultured in floating nets there. Other smaller and less frequent blooms
occurred in the bay the next year. This algal bloom was caused by the
dinoflagellate species Cochlodinium polykrikoides. This was thought to be the
first bloom of Coclodinium in these waters, or any in Indonesian waters. The
highest abundance of Cochlodinium during the incident reached to 3.07 x 107
cells.l-1. Mass fish mortality in the floating nets was due to oxygen
depletion, mainly during the night time. The clogging of their gills by dense
phytoplankton cells was assumed to be the cause. The population explosion of Cochlodinium
was triggered by a high ratio of nitrate and phosphate concentration in the
waters. The nutrient ratios of N/P in the water were high, indicating nitrate
as a triggering factor and phosphate as a limiting factor.
Author: Tumpak Sidabutar
Journal Code: jpperikanangg160004
