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Facilitative and Inhibitory Interactions Among Estuarine Meiobenthic Harpacticoid Copepods
Author(s) -
Chandler G. Thomas,
Fleeger John W.
Publication year - 1987
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1939882
Subject(s) - meiobenthos , biology , ecology , microcosm , detritivore , colonization , burrow , estuary , trophic level , abundance (ecology)
In the meiofauna communities of Louisiana estuaries (USA), the harpacticoid copepods Scottolana canadensis and Pseudostenhelia wellsi are predominant species. Scottolana canadensis is a semisessile burrow—dweller capable of subsurface suspension and deposit feeding. Pseudostenhelia wellsi is also semisessile but builds extensive networks of mucus tubes within the top 1 cm of muddy sediments, and appears to graze on its inner tubewalls. Tube building by P. wellsi generates meiofauna—sized structure and adds cohesiveness to surface sediments, as well as providing potential food and grazing substrates for other meiofuna. Monospecific patches of P. wellsi and S. canadensis (250 individuals/5 cm 2 ) were artificially generated in laboratory microcosms to determine if the unique lifestyle and sedimentary effects of either species facilitate or inhibit colonization by two other errant, burrowing harpacticoids common in the community, Nitrocra lacustris and Cletocamptus deitersi. These two species share similar foraging and burrowing behaviors and similar effects on sediment structure, which sharply contrast with those of P. wellsi and S. canadensis. Pseudostenhelia wellsi tube patches facilitated colonization by both S. canadensis and N. lacustris, but strongly inhibited colonization by C. deitersi. Scottolana canadensis patches were unattractive to N. lacustris. As P. wellsi showed the strongest effects on colonization by other harpacticoids, its mechanisms of facilitation/inhibition were also studied. In laboratory microcosms, cultured S. canadensis and N. lacustris were offered patches of azoic sediments, mucin—enriched sediments without structure, azoic sediments with agar tube mimics (structure), and sediments with natural P. wellsi tubes (mucus and structure). Both mucus enrichment and inert tube structure acted as strong facilitants to N. lacustris copepodites and adults overall. However, neither effect alone facilitated patch colonization by N. lacustris adult females and S. canadensis copepodites and adults. Their colonization was facilitated specifically by natural P. wellsi tubes. These experiments demonstrate that species interactions in harpacticoid communities can quickly influence spatial patterns, and those patterns may be mediated by species—specific effects on the sedimentary environment (e.g., mucus tube, burrows, increased flushing, erodability, etc.). However, spatial patterns cannot be predicted easily by contrasting the compatibility of one species' biogenic effects with those of another.