Gelatinous zooplankton versus Algerian environmental factors

Abstract Factors governing gelatinous zooplankton distributions and dispersal have long interested pelagic ecologists. The objective of the present study was to investigate the distribution of gelatinous zooplankton in relation to environmental parameters of coastal Algeria (Southwestern Mediterranean Sea). The zooplankton samples were collected on nine stations located in the central (Sidi Fredj) and western (Habibas Islands) sectors of the Algerian coast during 2012 and 2013. A total of 48 species belonging to 4 groups: Cnidaria, Tunicata, Chaetognathae and Mollusca have been recorded. Their composition showed a variable distribution in both investigated zones according to ANOSIM (p < 0.05) whatever the sampling period and between May and July for Habibas Islands and confirmed by NMDS, but no differences were detected between the sampling periods for Sidi Fredj. The redundancy analysis was used to identify different sample assemblages. It showed relationships between temperature, salinity and chlorophyll a with zooplankton abundances. Temperature was found to be the strongest explanatory variable for some Cnidaria (e.g. Aglaura hemistoma, Rhopalonema velatum, Liriope tetraphylla and Pelagia noctiluca) and Appendicularia (e.g. Oikopleura longicauda, Oikopleura fusiformis and Fritillaria pellucida) while, the development of Doliolum nationalis and Creseis virgula were related to salinity variations.