MEPS 354:181-189 (2008)  -  DOI: https://doi.org/10.3354/meps07178

ABSTRACT: We tested the hypothesis that nutrient enrichment affects recruitment of the oyster Saccostrea glomerata and the barnacle Hexaminius popeiana, which are dominant occupiers of space on tree trunks in temperate mangrove forests in New South Wales, Australia. We measured recruitment on artificial settlement plates at high and low intertidal levels under ambient conditions and where we manipulated nutrient levels by adding fertiliser to the water column for 2 mo. To determine whether nutrients influenced temporal patterns of settlement and early mortality of larvae, we quantified recruitment for 2 sampling intervals: on plates that were replaced 4 times at 2 wk intervals and on those left in the field for the entire 2 mo. For both intervals, recruitment of oysters was 3 to 4 times and significantly higher under elevated than ambient nutrient conditions. Recruitment of barnacles was also significantly higher under elevated nutrient conditions, but only on plates sampled at 2 wk intervals. On plates left out for 2 mo, the effect of nutrients on recruitment was variable, but recruits were generally higher in number under ambient conditions, suggesting that nutrients might enhance postsettlement mortality. Nutrient enrichment clearly affected recruitment of oysters and barnacles, possibly by mimicking natural settlement cues of conspecific individuals. Considering the central role of recruitment to the population dynamics of marine benthic invertebrates, nutrient enrichment has the potential to alter species assemblages in estuarine and marine habitats.

KEY WORDS: Larval settlement · Postsettlement mortality · Gregarious settlement behaviour · Nitrogen · Phosphorus · Eutrophication · Substratum type · Estuaries