Fish assemblage structure in shallow waters of the Mellah Lagoon (Algeria): Seasonal and spatial distribution patterns and relation to environmental parameters

Abstract

Embarek R., Amara R., Kara M.H. 2017. Fish assemblage structure in shallow waters of the Mellah Lagoon (Algeria): Seasonal and spatial distribution patterns and relation to environmental parameters. Acta Ichthyol. Piscat. 47 (2): 133-144.Background. Southern Mediterranean lagoons are poorly studied. The Mellah Lagoon is the only coastal lagoon in Algeria. Characterized by low anthropogenic pressure it has a crucial environmental and socioeconomic role because of its fishing activities and conservation status. The spatial and temporal variations of fish assemblage structure in relation with the environmental parameters were investigated. This study contributes to a better understanding of the functioning of the Mellah Lagoon, thus providing useful data regarding its conservation and management. Materials and methods. Sampling was carried out monthly during one year at four stations with a beach seine of 3-mm mesh. Environmental variables were measured during each sampling. Canonical correspondence analysis (CCA) and cluster analysis were used to assess environmental influences on fish spatio-temporal assemblages. (Valenciennes, 1847). Resident species presented the highest abundance values, accounting for 96% of the total number of fish captured, while marine migrant species that use the lagoon as a nursery ground contributed the most to the community species richness (7 species). Atherina boyeri (87.59% of total catch by number) was the most abundant species. Environmental parameters measured were uniform across the whole lagoon. However, temperature and salinity showed a seasonal pattern. The CCA analysis based on species abundance indicated the absence of clear spatial and temporal patterns in fish assemblage. The majority of the species had mean values of distribution in relation to environmental variables. Conclusion. The fish assemblage of the shallow water (<1.5 m) of the Mellah Lagoon is characterized by a small number of species dominated by resident species. The low species richness, the dominance of resident species, and the weak spatial and temporal patterns in the fish assemblage are mainly the result of a high degree of confinement because of the low freshwater inputs from the wadis and the limited tidally-driven exchanges between the lagoon and the sea. To maintain high biodiversity and a sustainable fishery in the lagoon, it is necessary to develop a management plan which would facilitate a proper water exchange between the lagoon and the sea and would promote colonization of the lagoon by marine species.

13‐year population survey of the critically endangered European eel in the southern Mediterranean region (Algeria)

“…Mellah lagoon (36° 54′ N–8° 20′ E) is a brackish coastal lagoon (salinity between 27 and 34) located on the extreme northeastern section of the Algerian coast. It has also been classified as a Ramsar site since 2004 and is part of the El Kala National Park, covering 865 ha with an average depth of 2.7 m (Embarek et al ., 2017). Its hydrological regime is influenced by the movements of marine waters that enter through a channel, and by the direct inputs of freshwater during rainfall events.…”

Social-Environmental Analysis for the Management of Coastal Lagoons in North Africa

“…There are pressures on El Mellah lagoon (Algeria) from aquaculture with organic matter enrichment of sediment (Embarek et al, 2017).…”

Fish food-web structure of a southern Mediterranean lagoon (El Mellah Lagoon, Algeria): what we can learn from stable isotope analysis

“…These interface ecosystems attract many aquatic species due to their variety of habitats, which enable the species to grow (Costanza et al, 1997). The fish populations in these paralic environments include marine and continental species that enter the lagoon at different stages of development (Embarek et al, 2017). Lagoon fish communities consist of mature individuals, which come to reproduce obligatorily, regularly, or occasionally, and juveniles, which use the environment to feed.…”