RECRUITMENT OF LARVAL FISHES INTO A NORTH-CAROLINA ESTUARY DURING A BLOOM OF THE RED TIDE DINOFLAGELLATE, GYMNODINIUM BREVE

An unprecedented bloom of the toxic dinoflagellate Gymnodinium breve i n coastal waters of North Carolina occurred during year three (fall-wi nter 1987-1988) of an eight-year larval fish study. This event was the basis for examining the possible effects of red tide on the estuarine recruitment of nine species of larval fishes. Densities of larvae for 1987-1988 were compared to their corresponding average densities for the two seasons prior to and five seasons after the red tide. Larval f ish recruitment for most species over the entire 1987-1988 season was not unusually low, although two of nine species did exhibit their 8-yr minima during this time. Densities for 1987-1988 were compared with t he densities averaged (by week) over the other 7 yrs and revealed thre e general patterns of response. Two species, Paralichthys albigutta (g ulf flounder) and Citharichthys spilopterus (bay whiff) had consistent ly low densities throughout their normal period of recruitment, sugges ting that their estuarine recruitment may have been impacted by the ef fects of G. breve even after the bloom ended. In contrast, Micropogoni as undulatus (Atlantic croaker) and Lagodon rhomboides (pinfish) densi ties were generally normal, or above normal, both during the bloom and for the remainder of the larval recruitment season. Five other specie s (Brevoortia tyrannus, Atlantic menhaden; Paralichthys lethostigma, s outhern flounder; Leiostomus xanthurus, spot; Mugil cephalus, striped mullet; Myrophis punctatus, speckled worm eel) had low densities durin g the bloom, but increased markedly later in the season. This pattern suggested these five species suffered immediate effects when the red t ide was extant, but had high recruitment success later in the season. In the first post-red tide year, six of the nine species had their hig hest mean catches over the first 14 wits of all 8 yrs and suggested a possible post-red tide beneficial effect on larval fish estuarine recr uitment.