Changes in trophic community structure of shore fishes at an industrial site in the Gulf of Aqaba, Red Sea

Abstract

The semi-enclosed Gulf of Aqaba is under high pressure by urban and industrial pollution, shipping and port activities as well as tourism. Off the Jordanian Red Sea coast, the trophic community structure of shore fishes was determined on coral reefs in front of an industrial area (disturbed), in a marine reserve and site without industry or port activities (undisturbed), as well as in a seagrass-dominated bay. Planktivores were the most abundant feeding guild on coral reefs as well as in the seagrass-dominated bay. The relative abundance of feeding guilds other than planktivores seems to be strongly influenced by the benthic habitat. Multivariate analysis clearly separated disturbed from undisturbed sites, whereas univariate measures, such as species richness, diversity and evenness did not reveal any negative impact of disturbance. The disturbance of the coral reefs led to changes in the fish community through the reduction of total fish abundance by 50%, increased total abundance of herbivorous and detritivorous fishes, decreased total abundance of invertebrate-and fish-feeders, and increased relative abundance of planktivorous fishes.

Impacts of contaminant sources on marine fish abundance and species richness: a review and meta-analysis of evidence from the field

“…For example, there is some evidence to suggest that fish farms disproportionately increase the abundance of pelagic fishes with predatory feeding habits and planktivores , Valle et al 2007, Fernandez-Jover et al 2008. In other habitats and contaminant source groupings, the response of different ecological groups appears to be highly variable and at times contradictory For example, in the Khalaf & Kochzius (2002) study, herbivores, detrivores, and planktivores experienced increased abundance and diversity in association with industrial contamination, while fish that feed on invertebrates or other fish decreased. In contrast, Otway et al (1996b) found that sewage contamination disproportionately favored fishes feeding on invertebrates and fish.…”

“…While inconsistent responses were obtained for species richness, it is possible that contamination may act to alter fish assemblages in ways that are not detected by simple diversity measurements. Several studies have shown significant changes in the abundance and trophic structure of fish assemblages, while little impact was detected by conventional diversity measures (Khalaf & Kochzius 2002, Guidetti et al 2003, Ribeiro et al 2008). More complex measures of biodiversity and/or community structure, such as the Shannon-Wiener diversity index, Pielou's evenness, or taxonomic relatedness (Costello et al 2001) may better characterize community responses to contamination than simple richness or abundance indexes (Washington 1984).…”

“…In an excellent study, Khalaf & Kochzius (2002) investigated the impacts of urban and industrial contamination in a heavily developed port in the Gulf of Aqaba, Jordan. They assessed the trophic community structure of coral reef fishes near disturbed and undisturbed sites and analyzed this data using a variety of univariate and multivariate measures.…”

MARS: biological indicators of natural and man-made changes in marine and coastal waters: scientific coordinators' introduction

“…In Jordan, local disturbance of coral reefs has led to a 50% decline in overall fish abundance, especially invertebrate feeders and piscivores. At the same time, the abundance of herbivores, detritivores and planktivores was seen to increase (Khalaf and Kochzius 2002). The decline of the reefs is attributed by some researchers to the persistent influx of nutrients from urban sewage and mariculture activity, claiming that oligotrophic conditions necessary for the thriving of coral have changed, increasing turbidity and boosting phytoplankton biomass near the northern coastline (Lazar et al in IUI 2001;Cariou and Erez in IUI 2001).…”

Do ectoparasites determine cleaner fish abundance? Evidence on two spatial scales

“…Corallivorous butterflyfish, for example, are invariably associated with areas of high live coral cover, and areas with relatively more live coral support greater densities of butterflyfishes (Cadoret et al 1995, Khalaf & Kochzius 2002. We therefore hypothesised that obligate cleaner fish should show similarly strong associations with areas rich in their preferred prey, namely parasitic gnathiid isopod larvae (Grutter 1997, Arnal & Côté 2000.…”