Patterns of microphytoplankton biomass and diversity in the southern Alboran Sea

Abstract

The southern Alboran Sea is a highly dynamic region in the Mediterranean. However, there is few data on microphytoplankton which is, an important component of the marine ecosystem. We therefore collected microphytoplankton samples and related the biomass and diversity patterns to ambient variability, considering cross-shore and longitudinal gradients. There was a general eastward decrease in both species richness and biomass, with Cape Three Forks as a transitional point. Diversity increased in coastal areas and decreased with depth. High chlorophyll-a concentrations corresponded to low temperature and low-salinity waters, indicating the Atlantic origin. Microphytoplankton biomass was low in comparison with total chlorophyll, suggesting a dominance of nano- and picophytoplankton. Biomass values increased in the stretch between Cape Three Forks and Al Hoceima Bay, an area highly influenced by upwelled water originating from the northern Alboran Sea. We suggest that the Western Alboran Gyre enhances the development of dinoflagellates while local upwelling enhances the development of diatoms. A statistical relationship was found between microphytoplankton biomass and diversity, especially when diversity was estimated as species richness. These results are crucial for understanding microphytoplankton dynamics and trends in an area that is undergoing climate-derived changes and biodiversity losses.

Spatial and seasonal fluctuations of Ichthyoplankton assemblage in the Mediterranean coast of Morocco (Southwestern Alboran Sea)

“…To normalize the number of egg and larval catches to a specific area of 10 square meters, the filtered depth and water volumewere taken into account. At each station, Sea Surface Temperature and Salinity were measured using a Neil Brown CTD (Conductivity-Temperature-Density) multisonde, the concentration of surface chlorophyll-a was measured by obtaining water samples through 1L-Niskin bottles, which were then analyzed using a 10-AU fluorometer (Idmoussi et al, 2021).…”

“…The Moroccan Mediterranean coast is part of the Alboran Sea located in the southwestern basin of the Mediterranean Sea (Diouri et al, 2020). This region is characterized by primary productivity that increases seasonally (Idmoussi et al, 2021). These relatively the most productive areas provide suitable conditions for marine fish reproduction and habitat for the life cycle of small pelagic fish (Diouri et al, 2020;Idmoussi et al, 2021;Papaconstantinou et al, 2000;Agostini et al, 2002;Coombs et al, 2003 ;Lloretet al, 2004).…”

“…This region is characterized by primary productivity that increases seasonally (Idmoussi et al, 2021). These relatively the most productive areas provide suitable conditions for marine fish reproduction and habitat for the life cycle of small pelagic fish (Diouri et al, 2020;Idmoussi et al, 2021;Papaconstantinou et al, 2000;Agostini et al, 2002;Coombs et al, 2003 ;Lloretet al, 2004). Its hydrology is mainly conditioned by the Atlantic jet (AJ), which enters through the Gibraltar strait (Idmoussi et al, 2021, Bormans et al, 1989and Lafuente et al, 1998.…”

“…These relatively the most productive areas provide suitable conditions for marine fish reproduction and habitat for the life cycle of small pelagic fish (Diouri et al, 2020;Idmoussi et al, 2021;Papaconstantinou et al, 2000;Agostini et al, 2002;Coombs et al, 2003 ;Lloretet al, 2004). Its hydrology is mainly conditioned by the Atlantic jet (AJ), which enters through the Gibraltar strait (Idmoussi et al, 2021, Bormans et al, 1989and Lafuente et al, 1998. This jet contributes to the maintenance of two anticyclone gyres: the Western Alboran Gyre and the Eastern Alboran Gyre, conferring specific properties to this part of the Mediterranean Sea (Idmoussi et al, 2021, Arnone et al, 1990and Vargas et al, 2002.…”

“…Its hydrology is mainly conditioned by the Atlantic jet (AJ), which enters through the Gibraltar strait (Idmoussi et al, 2021, Bormans et al, 1989and Lafuente et al, 1998. This jet contributes to the maintenance of two anticyclone gyres: the Western Alboran Gyre and the Eastern Alboran Gyre, conferring specific properties to this part of the Mediterranean Sea (Idmoussi et al, 2021, Arnone et al, 1990and Vargas et al, 2002. Most fish pass through the pelagic stage, which lasts from weeks to months (Blabolilet al, 2023, Brothers et al, 1983 andVictoret al, 1986).…”