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

Abstract

In soft-sediment systems, terrestrial sediment deposits may result in a marked change in habitat and benthic community composition. We conducted a series of experiments to investigate the behavioural response of juveniles of 2 bivalve species common on New Zealand intertidal sandflats (Paphies australis and Macomona liliana) to terrestrial sediments. Both species are able to actively disperse as juveniles and do so in response to 'unfavourable' conditions. In the laboratory, we investigated the ability of these potential colonists to burrow into thin (0.5, 1.0 cm) surface and submerged terrestrial sediment layers, and their subsequent ability to burrow into natural sediments. Field experiments assessed their response to terrestrial sediments that had been 'aged' in the natural estuarine environment for different lengths of time (up to 1 mo). Exposure to terrestrial sediment treatments negatively affected both species, with fewer individuals burrowing into the terrestrial sediment treatments. In the laboratory, burrowing was slower in the 1 cm-thick surface layers than in the 0.5 cm-thick and submerged layers, and the subsequent burrowing rate in natural sand of individuals recovered from these treatments was similarly affected. This latter effect is important as it suggests that settlement by juvenile bivalves on terrestrial sediment deposits can have a lasting effect even if an individual is able to find a more suitable habitat at a later date. In the field, dispersal of M. liliana away from the terrestrial sediment treatments was reduced, even after the sediment had been 'aged' on the sandflat. Depending upon the extent and frequency of disturbance, terrestrial sediments are likely to have important effects on the population and community dynamics of mobile bivalve species, and at a wider scale than that of their immediate impact.

Effects of Polyester Microfibers on Microphytobenthos and Sediment-Dwelling Infauna

“…When bivalves are exposed to contaminants or other stressors, their burial capacity 40 , activity levels 41,42 and feeding behaviours 17,19 may be affected. These behavioral changes are likely associated with changes in their energy reserves, growth and weight, as documented for other invertebrates 30,[43][44][45] .…”

Invasive seaweed enhances recruitment of a native bivalve: roles of refuge from predation and the habitat choice of recruits

“…Recruitment in such populations is often poor, and smaller size or age classes are generally underrepresented even though soft-sediment bivalves are not generally considered recruitment limited (Olafsson et al 1994). Although pre-settlement processes such as adult -larval interactions and larval supply are important, post-settlement processes such as predation, active habitat selection and post-larval dispersal of recruits (defined in the present study as post-settlement juveniles) are also important in structuring juvenile and adult populations (Olfasson et al 1994, Nielson & Franz 1995, Hewitt et al 1997, Beukema & Dekker 2003, Cummings & Thrush 2004.…”

Rates of post-larval bedload dispersal in a non-tidal soft-sediment system

“…Dispersal also depends on species-specific differences in reproductive modes and development, which can play a vital role in local population fluctuations (Thorson 1950(Thorson , Ólafsson et al 1994. High rates of post-larval dispersal have been recognized as important in the recolonization process in response to disturbance, especially small-scale disturbances (Whitlatch et al 1998), and their contribution to higher resilience in benthic communities (Cummings & Thrush 2004, Thrush et al 2008, Norkko et al 2010.…”