title: Biodiversity differentials between the numerically-dominant macrobenthos of seagrass and adjacent unvegetated sediment in the absence of sandflat bioturbation.
abstract: Species composition, abundance and biodiversity of the South African estuarine invertebrate fauna are known to show marked differentials between seagrass beds and adjacent unvegetated sands in enclosed estuarine/marine bays. Such differentials were investigated at four disparate localities in a bay lacking the callianassid bioturbation of other local sites. Here there were no such marked or consistent differences: <50% of differentials were statistically significant, with seagrass showing the lower, not higher, level in half of those. Overall, faunal abundance was lower in seagrass in the ratio of 0.64 : 1, whilst species density was higher but only by 1.13 to 1. Seagrass assemblages at a given locality were more similar to those of the adjacent bare sand than they were to seagrass assemblages at other localities, and likewise in respect of those in the bare sand. This suggests that marked differentials, where they occur, may result not from any supposed favourability of seagrass as a habitat but from the operation of processes within the unvegetated-sediment compartment of the system.
authors: Department of Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape 6140, South Africa; Knysna Basin Project Laboratory, Knysna, Western Cape 6570, South Africa. Electronic address: r.barnes3@uq.edu.au.
authors: R S K
authors: RS
authors: Barnes
authors: Knysna Basin Project Laboratory, Knysna, Western Cape 6570, South Africa.
authors: M K S
authors: MK
authors: Barnes
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D044822:Biodiversity; D016000:Cluster Analysis; D017753:Ecosystem; D063366:Estuaries; D019015:Geologic Sediments / Q000469:parasitology*; D007448:Invertebrates / Q000502:physiology*; D013019:South Africa; D035962:Zosteraceae / Q000469:parasitology*
keywords: Benthos; Biodiversity; Bioturbation; Knysna; Sandflat; Seagrass