Sessile invertebrate assemblages on artificial structures at a commercial kelp farm and on natural substrates at an adjacent kelp forest site, Lüderitz, Namibia: baseline patterns of spatial and temporal variation
Year: 2026
Type: article
Abstract: Kelp aquaculture is expanding globally, yet its role in supporting sessile invertebrate biodiversity relative to natural kelp forests remains poorly understood. This study described sessile invertebrate assemblage in a natural kelp forest at Diaz Point and a kelp farm at Shearwater Bay in Namibia’s Benguela upwelling system. Sampling was conducted across multiple months in 2024 using presence/absence data to quantify species richness, community composition, and temporal variation. A total of 30 sessile invertebrate taxa from eight phyla were recorded. Species richness was higher at the natural kelp forest (25 taxa) than at the kelp farm (19 taxa). Additionally, community composition differed significantly between sites and months (PERMANOVA), with site explaining more variation than temporal effects. Ordination (PCoA) indicated clear separation between assemblages, with the kelp farm showing more clustered and compositionally similar samples. The kelp farm assemblage was largely characterized by the frequent occurrence of Mytilida and Balanomorpha, whereas the natural kelp forest supported a broader assemblage including sponges, anemones, bryozoans, and polychaetes. Substrate use was stable and evenly distributed across artificial structures at the farm, while the native kelp forest showed greater temporal variability in substrate occupation. Results indicate that kelp aquaculture structures support distinct fouling communities but show lower taxonomic richness and compositional heterogeneity compared to natural kelp forests. Differences in assemblage patterns were primarily associated with habitat type and structural context.
Source: Aquatic Ecology
Institutions: University of Namibia, Kelp Blue (Namibia), Kelp Forest Foundation
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204475203