Experimental evidence of passive accumulation of marine bivalve larvae on filamentous epibenthic structures

Abstract

A series of multifactorial experiments were carried out, in the field and in a flume, to test the hypothesis that early recruitment of semimobile bivalve spat on an epibenthic filamentous substratum is directly related to the heterogeneity (branching pattern) and the diameter of their individual branches or filaments and to evaluate the likelihood that passive settlement processes influence bivalve larval early recruitment on filamentous natural epibenthic substrata. The experiments were carried out with three-dimensional plastic structures similar in shape to hydroids and filamentous benthic algae-the preferred larval settlement substrata of several bivalve species in the field. Field experiments showed a highly significant effect for both branch heterogeneity and diameter. The 3-D structures collecting the highest number of spat per unit area were those offering smallest diameter and heterogeneity. Flume experiments that used inert particles and the same silicone-coated, 3-D structures reproduced early recruitment abundance patterns observed on heterogeneous structures in the field. Comparison of results from the field to those from the laboratory suggests that passive settlement processes are sufficient to explain early recruitment patterns of some bivalve species on scales of order 10 cm, although alternative, biological hypotheses were not tested in this study.

Observations of particle capture on a cylindrical collector: Implications for particle accumulation and removal in aquatic systems

“…From these parameters, one can es- Table 3. Capture efficiencies computed from data collected by Harvey et al (1995). Table 4.…”

“…Thus, it is useful to consider how capture efficiency varies across collector size, d c , given a fixed value Harvey et al (1995) in flume experiments simulating larval settlement. Multiples of the above two-dimensional structure were assembled to make a three-dimensional branch structure.…”

“…Further, Eckman (1983) showed that benthic recruitment is strongly dependent on the presence and numerical density of stem structures. Harvey et al (1995) provided experimental support for hydrodynamic controls on the settlement of bivalve larvae to filamentous branches of benthic algae. Finally, submarine pollination relies on the encounter rate of pollen with individual vegetative elements.…”

“…A cylindrical geometry approximates a variety of natural collectors such as reed-like wetland vegetation (e.g., Spartina alterniflora, Phragmites australis); submerged benthic plants and algae (Harvey et al 1995); and cilia, bristles, tube-feet and other filamentous structures of suspension feeders (Shimeta and Jumars 1991;Wildish and Kristmanson 1997;Riisgard and Larsen 2001). The relevant length scale for flow around a cylinder is the diameter, d c , and flow structure is defined by the collector Reynolds number, Re c ϭ ud c /v, where u is flow velocity and v is kinematic viscosity.…”

Structure and density population of the invasive mollusc Limnoperna fortunei associated with Eichhornia crassipes in lakes of the Middle Paraná floodplain

“…This coincides with the work done by Ohtaka et al (2011) in an inland lake in Cambodia, Southeast Asia, where they also found small L. fortunei (1.96-12.7 mm) attached only to E. crassipes roots even though there were other macrophytes available. Several studies have demonstrated the importance of filamentous substrates such as aquatic macrophytes and filamentous algae in the settlement of larvae and juveniles of marine and freshwater bivalve species (Bayne, 1964;Ackerman et al, 1994;Cáceres-Martínez et al, 1994;Harvey et al, 1995;Folino-Rorem et al, 2006). Dreissena polymorpha pediveligers have shown to prefer filamentous substrates, such as aquatic plants (Lewandowski, 1982).…”