Date of Award

1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

In Louisiana, USA, marshes, the harpacticoid copepods Scottolana canadensis and Pseudostenhelia wellsi are community co-dominants with similar lifestyles. Scottolana canadensis is a semi-sessile burrow-dweller capable of subsurface suspension and deposit feeding. Pseudostenhelia wellsi is a semi-sessile tube-building copepod that continuously corkscrews back and forth within its tube and appears to graze on the inner tube walls. Monospecific patches of both species (250 (.) 5cm('-2)) were generated in laboratory microcosms to determine their effects on colonization by two completely errant, burrowing harpacticoids, Nitocra lacustris and Cletocamptus deitersi, that have similar foraging and burrowing behaviors and similar effects on sediment structure. Pseudostenhelia wellsi tube patches facilitated colonization by S. canadensis and N. lacustris, but strongly inhibited colonization by C. deitersi. Scottolana canadensis patches were significantly unattractive to N. lacustris and inhibited their immigration. Mechanisms of facilitation were tested with colonization experiments offering patches of sterile sediments, natural P. wellsi tubes, P. wellsi agar tube mimics, and patches of pure mucin-enriched sediments. These experiments showed that both mucus and inert meiofaunal-sized tube structure act as strong facilitants to N. lacustris copepodites and adults overall. Patch colonization by Nitocra lacustris adult females and S. canadensis copepodites and adults was not facilitated by mucus or tube structure alone, but was strongly facilitated by natural P. wellsi tubes. These experiments demonstrate that species interactions may influence spatial patterns in harpacticoid communities, but assemblages are not consistently predictable based on similarities/dissimilarities in species' functional effects on muddy sediment structure.

Pages

101

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