In situ habitat selection by settling larvae of marine soft‐sediment invertebrates

Abstract

To test whether larval selectivity at settlement contributes to distributional patterns of benthic infauna, we conducted three reciprocal sediment transplant experiments at 15‐m‐deep coarse‐sand and muddy‐sand sites (∼3 km apart) on the continental shelf near Tuckerton, New Jersey. During 3‐ to 5‐d deployments in 1994, larvae of the surfclam, Spisula solidissima, selected coarse sand over muddy sand, and capitellid polychaetes selected muddy sand over coarse sand, regardless of site. Thus, larvae of both taxa selected sediments typical of adult habitats, displaying selectivity consistent with previous flume experiments. Settlement intensity changed significantly over the ∼6‐week period during which experiments were conducted. Several other taxa exhibited selectivity consistent with field distributions, and several were nonselective. Significant site differences in settlement intensity were also observed on some dates for several taxa. Plankton pump samples taken at the sites during tray experiments suggested that significant differences in supply of surfclam larvae over the 3‐km scale contributed to between‐site differences in settlement. In the later experiments, surfclams in experimental trays were larger than would be expected for recent settlers, suggesting that postsettlement migration and selectivity occurred on small scales. These experiments demonstrate that differences in larval supply over scales of kilometers and time scales of weeks can affect settlement intensity but that habitat selection by settling larvae of some species of soft‐sediment invertebrates may set initial distribution patterns.

Effects of physical disturbance on the cold-water megafaunal communities of the Faroe–Shetland Channel

“…Reduced sediment heterogeneity was apparent in the disturbed areas at Laggan; this leads to reduced diversity in the deep sea (Levin et al 2001). The blanketing of the seabed with sediment of a different composition, such as occurred at Laggan, has been shown elsewhere to result in conditions unfavourable to the typical resident communities, reducing immigration of mobile fauna and limiting larval settlement (Snelgrove et al 1999), and increasing recovery time. The increase in suspended particulate loading as a result of disturbance at Laggan may have lead to clogging of filter feeding apparatus of some organisms (Sharma et al 2001).…”

Causes of decoupling between larval supply and settlement and consequences for understanding recruitment and population connectivity

“…Ideally, larval collectors and artificial 10 substrates should minimize disturbance to the natural flow so that larvae approaching the 11 collecting device are not carried away or attracted in a way to reduce or increase collection 12 efficiency in an artificial way. Pumps have been designed to minimize flow disturbance in some 13 field conditions (Doherty and Butman, 1990;Snelgrove et al, 1999), but it is difficult to evaluate 14 the hydrodynamic effect of collectors in the field. Evaluations of sediment collectors (e.g., 15 Hargrave and Burns, 1979;Black and Rosenberg, 1994) will not necessarily apply to larval 16 collectors since they do not account for larval behavior in the presence of turbulence.…”

Behavioural response of juvenile bivalves to terrestrial sediment deposits: implications for post-disturbance recolonisation

“…For example, post-larvae of the bivalve Spisula solidissima demonstrate active choice of sediments characteristic of their natural habitat in flow conditions (Snelgrove et al 1999), as do Macoma balthica and Cerastoderma edule (de Montaudoin 1997, Huxham & Richards 2003, the polychaetes Pectinaria koreni (Olivier et al 1996b) and Capitella sp. (Hsieh & Hsu 1999) and the oligochaetes Paranais litoralis (Nilsson et al 2000) and Doliodrilus tener (Hsieh & Hsu 1999).…”