EFFECTS OF SPATIAL ORIENTATION OF MULTIPLE PLATE ARTIFICIAL SUBSTRATES ON INVERTEBRATE COLONIZATION¹

Abstract

Jumbo multiple plate samplers were suspended in a river at 0.3 and 1 m depth in one of three orientations: interplate spaces closed to downwelling light and open to flow, open to light and flow, or open to light and closed to flow. Mean numbers of colonizing taxa and individuals were not significantly different among orientations after eight weeks of submergence. All variables tested decreased significantly with depth. Mean number of taxa, number of individuals (1 m only), and insect diversity decreased between samplings at four and eight weeks for samplers that were closed to light and open to flow. All orientations, depths, and durations had one‐half to two‐thirds of the total taxa. Colonization was affected by location in the river and position on sampler suspension equipment. The results indicate lack of orientation effects on colonization or high variability that obscured such effects. The sampler suspension equipment possibly increased among‐sampler variability by forming artificial snag habitats, and interplate light and flow conditions at different orientations may not have been sufficiently distinct to elicit different biological responses. Individual samplers provided diverse microhabitats regardless of orientation, but it would be prudent to include orientation among the variables considered in use of multiple plate samplers.

Artificial crevice habitats to assess the biodiversity of vagile macro-cryptofauna of subtidal rocky reefs

“…Despite several studies using multi-plate samplers in fresh water (e.g. Slack et al 1988), there have been few published studies that have applied this technique to marine environments. Most studies of reef cryptofauna have focussed on meiofauna or small macrofauna that inhabit small spaces within coral rock (Hutchings and Weate 1977) or filamentous algae on hard surfaces in estuarine waters (Atilla and Fleeger 2000) or animals that inhabit the spaces within kelp holdfasts (Smith 1996;Smith et al 1996;Coleman et al 2007) or coralline algal turf (Kelaher 2002).…”

“…Multi-plate samplers (Hester and Dendy 1962) have been used in the study of freshwater and estuarine invertebrates. For this type of work, the crevices between plates range from 0.3 to 1.3 cm and plate areas from 57 to 121 cm 2 (Fullner 1971;Slack et al 1988;Atilla and Fleeger 2000). Many marine reef organisms typically occupy much larger crevices.…”