title: Effects of altered estuarine submerged macrophyte bed cover on the omnivorous Cape stumpnose Rhabdosargus holubi.
abstract: The ecological importance of submerged macrophyte beds to fishes within estuaries was investigated through the example of the ubiquitous Cape stumpnose Rhabdosargus holubi, an omnivorous, vegetation and estuary-dependent species, using stable-isotope techniques and long-term abundance (catch-per-unit-effort) data from the East Kleinemonde Estuary, South Africa. Outputs from a Bayesian mixing model using δ(13) C and δ(15) N signatures indicated that the submerged macrophytes Ruppia cirrhosa and Potamogeton pectinatus were not a primary source of nutrition for R. holubi, confirming previous work that revealed that macrophytes are consumed but not digested. Long-term seine netting data showed reduced abundance of R. holubi during a prolonged period of macrophyte senescence, suggesting that submerged macrophyte habitats provide shelter that reduces mortality (predation risk) and a food-rich foraging area.
authors.affiliation: Department of Zoology and Entomology, Rhodes University, Grahamstown 6140, South Africa South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa.
authors.forename: J N
authors.initials: JN
authors.lastname: Sheppard
authors.forename: A K
authors.initials: AK
authors.lastname: Whitfield
authors.forename: P D
authors.initials: PD
authors.lastname: Cowley
authors.forename: J M
authors.initials: JM
authors.lastname: Hill
mesh_terms: D035961:Alismatales / Q000502:physiology*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001499:Bayes Theorem; D004777:Environment; D005247:Feeding Behavior; D010473:Perciformes / Q000502:physiology*; D031821:Potamogetonaceae / Q000502:physiology*; D013019:South Africa