Seasonal patterns of the macrozoobenthic community structure according to environmental conditions in a western Mediterranean lagoon close to the Gibraltar strait

The seasonal variability of the macrozoobenthic community was investigated in a north african lagoon (the smir lagoon) of the mediterranean. the total abundance and species number showed a seasonal pattern,with higher values in winter and lower ones in summer. the variability in physico-chemical (salinity,temperature,dissolved oxygen and ph) and biological (seaweed-seagrass cover) factors provided diverse habitats,and species-specific habitat association of organisms in response to environmental variability. the community structure had two major season groups related to the species composition and was mainly due to the abundance of cyathura carinata and melita palmata. the first discrimination group represented the summer community was explained by the high water temperature and salinity values and by the strong reduction of the vegetation cover,whereas the second one characterized the spring,autumn and winter community. sediment was not considered as a temporal structuring factor of the macrofauna community due to lower sediment inputs into the lagoon and the absence of any significant changes in sediment habitats. the significant correlations between water variables and the benthic structure,particularly in summer,support that salinity and temperature should be considered among factors structuring the temporal pattern of composition and abundance of the community. in the outermost part of the lagoon connected with the mediterranean sea,ph,dissolved oxygen,macrophyte beds and hydrodynamics could be considered as contributing parameters of the seasonal community structure of this lagoon area. thus seasonal dynamics of the faunal assemblages seemed to be also driven by biotic effects as recruitment trends,food availability and inter-specific competition. © 2017,university of mohammed premier oujda morocco.