Influences of oceanographic and meteorological features on reef fish recruitment in Hawai’i

Larval fish recruitment is generally highly variable in space and time, and can significantly influence adult population abundance, density and distribution, as well as community structure in coral reef systems. We investigated relationships between reef fish recruitment (data from the West Hawai’i Aquarium Project) and oceanographic and meteorological variables (measures of eddy presence and frequency, El Niño Southern Oscillation, sea surface temperature, sea surface height, chlorophyllaconcentration and rainfall). We compared these variables at different time scales—monthly and annually—to substantiate 1 of 3 possible hypotheses about the relationship between eddies and other oceanographic features and fish recruitment: (1) they are positively correlated, indicating that eddy activity could enhance recruitment; (2) they are negatively correlated, indicating that eddy activity may reduce or inhibit recruitment; and (3) they are not correlated, indicating that eddy activity has no impact on recruitment. We found several potential linkages generally supporting the hypothesis that eddies negatively correlate with fish recruitment. In contrast to previous work, we found significant negative correlations in annual patterns of cold-core mesoscale eddies and young-of-the-year totals on the west coast of the island of Hawai’i. We also investigated time lags between monthly recruitment data and oceanographic data several months earlier, consistent with planktonic larval duration ofZebrasoma flavescensandCtenochaetus strigosus; these phase shifts also produced negative correlations. Our results are exploratory and are only correlations, and thus do not suggest causation; further exploration is needed to substantiate the possibility that eddies have a negative influence on reef fish recruitment. However, these results do call into question that eddies in west Hawai’i have a positive impact on fish recruitment, a theory that has persisted in the literature for nearly 30 yr.