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A posteriori Investigation of Spatial Arrangements in Gnathostomulida and Copepoda
Author(s) -
Farris Richard A.,
Lindgren Eric W.
Publication year - 1984
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19840690312
Subject(s) - species richness , range (aeronautics) , fauna , ecology , biology , composite material , materials science
Copepods at MHTL and gnathostomulids from MHTL to sublittoral sands were studied in 162 samples from Tucker's Town Cove beach, Bermuda. Species were analyzed for mean density (X̄), mean crowding (), and patchiness (/ X ) using Lloyd's a posteriori statistic for mean crowding. Diversity was computed using the Shannon‐Wiener Index ( H ′). Copepoda were found to be nearly three times more abundant than Gnathostomulida at the MHSL site. 74% of the copepods were found in the surface cm of sediment while 87% of the gnathostomulids were located between 1–4 cm deep and within the RPD layer. Similar gnathostomulid distributions were found at MSL and sublittorally. Mean density and mean crowding were highly variable for the numerically dominant species in each group, whereas patchiness was relatively constant with values ranging between/X̄ = 1.50 to 2.73 for P = 0.05. Such consistency in patchiness between two diverse taxa having distinctly different vertical distributions may suggest that there exists an optimum degree of patchiness for interstitial fauna and that the optimum values may lie within a range similar to that of the numerically dominant Copepoda and Gnathostomulida. Overall patchiness was slightly higher in the gnathostomulids and in the rarer species as predicted by Lloyd's statistic. Diversity was higher in the Copepoda, attributable primarily to species richness.