Presence of the Mesopodopsis slabberi (Van Beneden, 1861) (Crustacea: Mysida) from the Mediterranean Sea coast of Turkey

Mysid, Mesopodopsis slabberi (Van Beneden, 1861) was for the first time recorded in İskenderun Bay (eastern Mediterranean). A total of 10 specimens belong to M. slabberi was collected at the depths between 0 and 2 m. This paper is on the first record of M. slabberi from the Levantine coast of Turkey.

Habitat value of a developing estuarine brackish marsh for fish and macrocrustaceans

Marsh creation receives worldwide attention in mitigating loss of coastal wetlands and in management retreat of estuaries. In the Westerschelde, the former Selena Polder, south from the marsh of Saeftinghe, developed into the Sieperda marsh after several dyke breaches. Soon after the tides regained access to the polder, a tidal creek was formed. After 10 years, a developing marsh system was found adjacent to a mature marsh system. This situation offered the opportunity to compare the utilization by nekton species of a natural mature marsh with a recently created developing marsh under similar circumstances. Between April and October 1999, both the mature Saeftinghe marsh and the developing Sieperda marsh were sampled every 6 weeks on 2 consecutive days. Each sampling occasion covered the whole tidal cycle. The most important environmental parameters (water height, temperature, salinity, turbidity and dissolved oxygen) were similar in both marsh creeks. A distinct difference in nekton community structure between the two marshes was observed. The total biomass and densities of nekton species were higher in Saeftinghe. In Saeftinghe, a density peak occurred in July and was mainly due to large numbers of the mysid, Neomysis integer. In Sieperda, maximum abundance of the mysid, Mesopodopsis slabberi, caused the peak density in September. This difference in species dominance was observed in all samples. Biomass peaked in July in the mature marsh and in October in the developing marsh. Mysid shrimp (N. integer) and fish (mainly Pomatoschistus microps) were the main contributors to the biomass Saeftinghe. Herring, sprat (Clupeidae) and shore crab (Carcinus maenas) were more important in Sieperda. For P. microps, distinct differences in length–frequency distributions were noted between the marshes. While creek morphology influences the abundance and species composition of visiting nekton, the age of a marsh and its maturity are believed to be the prime factors in determining the habitat function of creek systems of developing and mature marshes.

Benthic Boundary Layer fauna from the Seine Estuary (eastern English Channel, France): spatial distribution and seasonal changes

One hundred and three suprabenthic hauls in the Seine Estuary were taken on a marine to fresh water gradient with a modified Macer-GIROQ sledge during 1996 to collect Benthic Boundary Layer fauna. Two main species assemblages were identified along the salinity gradient: (1) a marine assemblage located in the downstream part of the estuary dominated by amphipods and mysids such as Schistomysis spp. and Gastrosaccus spp.; (2) an estuarine assemblage essentially dominated by the mysid Neomysis integer, recorded along the salinity gradient with maximal abundance observed between 15–10 psu. The decapod Palaemon longirostris and the goby Pomatoschistus microps were located in the upstream part of the estuary where they presented maximal abundances. Some species used the estuary during juvenile development such as the mysid Mesopodopsis slabberi (Van Beneden, 1861) and decapod Crangon crangon. Although the morphological characteristics of the Seine Estuary (weak estuarine area and important dredging) are different than other major European estuaries such as Gironde, Westerschelde and Ems, the longitudinal distribution of the demersal community presented similar patterns in all sites. Nevertheless, monthly sampling permitted to determine the seasonal location and abundance changes of the demersal assemblages in the Seine estuary. Marine assemblages presented maximal densities during summer and autumn while estuarine species were most abundant during spring and summer. Longitudinal changes of main demersal species during an annual cycle showed an increase of spatial distribution along the salinity gradient for marine and neritic species during spring and summer with a penetration of species in the estuary. The abundances of both assemblages were very high (annual mean >5000 ind 100 m−3) whereas the biomass of the estuarine assemblage was very important (annual mean ≅38 g ash-free dry weight 100 m−3).