Predicting the magnitude of temporal variation in young-of-year class strength of surfperch (Teleostei : Embiotocidae)
Raffles Bulletin of Zoology (Supplement)
Members of the fish family Embiotocidae (surfperches) are viviparous and give birth to fully-developed, non-dispersing juveniles. We explored: a) whether fluctuations in recruitment of young-of-year surfperches were similar among a series of shallow rocky reefs off Southern California, USA and b) whether spatial variation in recruitment fluctuations mapped onto spatial differences in the fluctuations of the local forage base on the reef. For both surfperches examined (black surfperch, Embiotoca jacksoni; striped surfperch, E. lateralis), recruitment varied comparatively little through time on some reefs while it fluctuated substantially on others. These fishes harvest invertebrate prey from specific benthic foraging microhabitats (algal turf for black surfperch; the red alga, Gelidium robustum for striped surfperch) and these microhabitats showed a range in dynamics among the reefs examined over a 12 year period. Interannual fluctuations in foraging microhabitat were a strong predictor of the extent to which the abundance of young-of-year surfperches fluctuated. However, the foraging microhabitat for black surfperch (algal turf) on a reef fluctuated independently of that for striped surfperch (G. robustum). As a consequence, the extent to which the abundance of young of one species of surlperch varied on a given reef was unrelated to that of its congener. These data show that: 1) the magnitude of temporal variation in year-class strength of reef-associated fishes was related to the magnitude of variation in the forage base; 2) reefs in close proximity can show a range in resource dynamics that can affect reproductive output and 3) the reproductive output even of closely-related species can fluctuate independently of each other on the same reef.