Functional diversity of the macro‑invertebrate community in the port area of Kerkennah Islands (Tunisia)

Abstract

The harbour area of Sidi Youssef in Kerkennah islands is characterized by specific anthropogenic pressures linked to fishing activities. To study the functional diversity of benthic macro-invertebrates, 10 stations located around the port and along the ship canal were sampled by SCUBA diving. Collected invertebrates were identified, counted and preserved. For the functional organization of the community, the most common biodiversity indices and functional groups were assessed at each station, and main physical and chemical parameters were measured. Results showed that the main apparent anthropogenic stress, that could lead to negative impacts on the studied area, was related to dredging/harbour activities. Suspension feeders, consisting essentially of polychaetes, which may be disturbed by water turbidity, dominated the stations farthest from the port, where the intensity of harbour activities is obviously reduced. On the contrary, carnivores dominated inside the port, possibly benefiting from fish-scraps discarded at the area, while stations close to the port appeared to be more balanced trophically. The applied biotic indices showed that the area is in good ecological status, except of the navigation channel and the port entrance, which were slightly degraded.

Spatial and Temporal Structures of the Macrozoobenthos from the Intertidal Zone of the Kneiss Islands (Central Mediterranean Sea)

“…The benthic community in the Kneiss Islands seems to be characterized by a structure and organization closely similar to ecosystems in other parts of the Mediterranean, dominated mainly by crustaceans, molluscs, polychaetes, cnidarians and echinoderms. This pattern has also been observed in other Mediterranean coastal sites, such as in the Kerkennah Islands [54], the Bay of Tunis, Ghar El-Melh Lagoon, the Tunis lagoon [55] [59]. However, it is well known that seagrasses increase habitat complexity and provide living space and shelter for a diverse animal community [60]- [62].…”

Functional uniformity underlies the common spatial structure of macrofaunal assemblages in intertidal seagrass beds

“…Most research into marine soft‐sediment functional diversity and assemblage structure has been devoted to changes in diversity patterns in response to major changes in habitat type, including those induced anthropogenically (e.g. Bremner et al ., , ; Afli, Ayari & Brahim, ; Bremner, ; Aloui‐Bejaoui & Afli, ). Virtually all studies of marine assemblage structure have also been concerned with patterns of relative component numbers (i.e.…”

Temporal variation of the algae-associated molluscan assemblage of artificial substrata in Bay of Tunis (Tunisia)

“…However, many factors can influence invasibility (Beisner et al, 2006;Stachowicz & Byrnes, 2006) including competition for the space and/or resources. Despite the presence of two alien species among the dominant species of the assemblage, the location of the algal turf near the harbour, potentially affected by eutrophication as in the smaller ports of Tunisia (Aloui-Bejaoui & Afli, 2012), is likely to favour invasion by most species. The rich and abundant assemblage, with consecutive settlements of different species throughout the year, which occupy space, and the diversity of feeding guilds, are the elements that probably control the invasion by more alien species (Stachowicz & Byrnes, 2006).…”