MEPS 410:43-54 (2010)  -  DOI: https://doi.org/10.3354/meps08636

ABSTRACT: Spatial pattern and intensity of recruitment have substantial effects on adult community structure in some but not all marine systems. Such ‘supply-side’ effects have been relatively poorly studied in soft-sediment habitats because of the difficulty of sampling very small infaunal recruits. I investigated whether spatial patterns of infaunal recruitment along an estuarine gradient could account for the observed cline in adult diversity. On 9 occasions spread over 13 mo, cores of sterile sediment from 2 different sources were embedded in beaches along the estuarine axis of Puget Sound, Washington, and sampled 6 wk later for new recruits. Identities and abundances of recruits (mostly polychaetes and bivalves) varied among seasons, but differed little between sediments from different sources. Contrary to expectations, neither recruit richness nor abundance was lower at the southern (more estuarine) end of the gradient, where adult taxonomic diversity is low. For a number of taxa and time periods, recruitment was actually stronger at the southern beaches. Multivariate differences between assemblages of recruits and adults were much greater at the southern sites, indicating that post-recruitment processes at these sites modify diversity and abundance patterns initially established by recruitment. These processes could include predation on juveniles, adult–juvenile competition, or physiologically stressful abiotic conditions.

KEY WORDS: Recruitment · Soft-sediment · Infauna · Estuarine · Supply-side · Polychaetes · Clams