Influence of shoreline configuration on spatial variation of meroplanktonic larvae, recruitment and diversity of benthic subtidal communities

Recruitment, abundance (percentage cover, density) and diversity (H') of a benthic subtidal community were examined in relation to large scale (greate r than or equal to 0.15 km) shoreline configuration in the St. Lawrence Est uary (Canada). Settlement panels were moored inside and outside bays of dif ferent sizes (0.15, 1.5, 4 and 7 km aperture) and along a portion of straig ht (approximate to 12 km) coast. Only the largest bay was sampled in 1993, while all bays and the straight coast were sampled in 1994. In 1993, recrui tment occurred only within the bay. No recruits were observed on moored pan els from zones external to the bay. Within the bay, percentage cover on pan els was greater than in zones external to the bay. In 1994, percentage cove r and the density of recruits were also greater within each bay than outsid e bays. No differences in diversity, percentage cover and density of recrui ts were observed among zones along the straight coast. Diversity was greate r in bays than along the straight coast and was greater inside bays of 1.5 and 7 km aperture than in zones external to the bays. Overall, diversity te nded to increase with increasing size of bay, the straight coast exhibiting the smallest values, in contrast, the density of recruits and percentage c over tended to decrease with increasing size of bay; smallest values were f rom the straight coast. Abundance of recruits was not directly related to p otential larval flux; current velocity alone explained 76% of the variation in density of recruits inside and outside of bays. Our study shows a relat ionship between shoreline configuration, the hydrodynamics, recruitment and benthic community characteristics. The generality of this relationship can be assessed by carrying out similar large-scale studies in other systems. (C) 1999 Elsevier Science B.V. All rights reserved.