Fine-resolution patterns of fouling community settlement, growth, and mortality using the CATAIN camera system

Abstract

Settlement dynamics and post-settlement mortality of sessile invertebrates is a black box in marine benthic invertebrate ecology. Most studies capture recruitment (i.e. survival of an individual until the researcher returns) rather than the in situ settlement timing, growth, and survival of newly settled sessile invertebrates. Quantification of settlement is labor-intensive and nearly impossible in remote habitats. Using the prototype camera system CATAIN (CAmera To Analyze Invertebrates), we have a glimpse into this important transitional period. CATAIN photographs the underside of its endcap (which acts as a settlement panel) on a sub-daily time scale, capturing settlement, growth, and post-settlement mortality in sessile invertebrates. In this study, image analysis was used to track individuals of 4 species every 4 h and explore fine-scale temporal dynamics of benthic invertebrates living in Woods Hole, Massachusetts, USA, over a 1 yr period. The goal of this study was to identify settlement rather than recruitment of common sessile species, as well as determine their early post-settlement mortality to better understand the relationship between settlement and recruitment. Beyond tracking seasonality of settlement, we found relationships between environmental factors (temperature, tidal phase, time of day) and settlement timing. We also found different growth rates between temperatures for 1 species. There were variable patterns of post-settlement mortality among species and lower mortality overall than reported by previous studies. This study demonstrates CATAIN as a promising research tool and investigates previously unknown early life-history characteristics of 4 common subtidal benthic invertebrates.