Compositional fidelity of phyla and classes in marine benthic associations

Abstract

<p>This study quantified the fidelity of higher taxa (phyla and classes) using comparisons between live communities and sympatric dead remains (death assemblages) using comprehensive surveys of benthic marine invertebrates from coastal habitats in North Carolina (U.S.A). To evaluate fidelity across multiple higher taxa simultaneously, concurrent live and dead samples were collected in a series of dredges over four field seasons (June 2011, November 2011, May of 2012, and April 2013) in Onslow Bay, North Carolina (U.S.A.). Dredging was conducted at 52 localities, 16 of which were sampled in multiple years, resulting in a total of 220 dredge samples collected from a variety of habitats, depths, and distances from shore. All live invertebrates were identified to the lowest taxonomic level possible (typically species). Encrusting species were excluded. Concurrent with live surveys, two bulk samples of dead material were collected at each locality. The results indicate that while community composition differed between the two assemblages across phyla and classes, these differences were predictable with an overabundance of robust and more preservable groups. In addition, dead molluscs appear to be a robust proxy for all taxa when tracking spatio-temporal patterns and shifts in community structure using a variety of diversity metrics. This suggests that despite filters imposed by differential preservation of taxa and time-averaging, the fossil record is likely to be reliable with respect to relative comparisons of composition and diversity in shallow marine benthic associations. This is consistent with previous work indicating that shallow marine death assemblages can yield robust ecological estimates adequate for assessing pristine ecosystems that existed under natural, pre-anthropogenic conditions.</p>