Browsing by Subject "Eutrophic waters"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Restricted
    Eutrophication-induced shifts in fish assemblages from a Mediterranean coastal lagoon
    (Elsevier, 2025-10-24) Zamora López, Antonio; Guerrero Gómez, Adrián; Torralva Forero, María del Mar; Zamora Marín, José Manuel; Oliva Paterna, Francisco José; Zoología y Antropología Física; Facultad de Biología
    Eutrophication remains a critical threat affecting estuarine and coastal lagoon ecosystems, largely driven by intensified anthropogenic pressures and exacerbated by climate change. Understanding the impacts of eutrophic processes on biological communities is essential to ensure effective conservation and management of these vulnerable environments. This study investigates the ecological consequences of eutrophication-induced algal blooms and hypoxia-mediated mass mortality events on fish communities in the Mar Menor coastal lagoon (Western Mediterranean Sea). We assessed temporal changes in fish assemblage structure and composition across three different periods: a baseline reference period (2002–2004), an algal bloom period (2018–2019), and a mass mortalities period (2020–2021). For that purpose, multiple community metrics were assessed, including species richness, abundance, biomass, β-diversity, functional guilds, and species dominance. Significant disturbances in fish abundance and biomass in response to critical eutrophic events were found, though species richness remained stable. Community similarity decreased during warmer seasons of eutrophic periods, but β-diversity values remained constant. Species-specific responses highlighted a marked decline of benthic taxa closely associated with bottom habitats, while zooplanktivores and planktivores became dominant, suggesting the emergence of top-down trophic control mechanisms. Additionally, during hypoxic events, large macrobenthivorous species appeared to seek refuge in shallow and more oxygenated areas, thus leading to evident shifts in fish assemblage composition. These findings provide robust evidence of structural and functional disruption in fish assemblages under eutrophic stress conditions. Our study underscores the relevance of long-term biological monitoring and adaptive management strategies in transitional systems, particularly under future climate and nutrient enrichment scenarios.
  • Thumbnail Image
    Publication
    Open Access
    Shallow waters as critical habitats for fish assemblages under eutrophication-mediated events in a coastal lagoon
    (Elsevier, 2023-07-24) Zamora López, Antonio; Guerrero Gómez, Adrián; Torralva Forero, María del Mar; Zamora Marín, José Manuel; Guillén Beltrán, Antonio; Oliva Paterna, Francisco José; Zoología y Antropología Física
    Eutrophication is a major driver of the degradation of transitional waters worldwide, especially in environments with a restricted connection to the sea, such as coastal lagoons. In recent decades, intensive agriculture and urban water inputs around the Mar Menor coastal lagoon (Western Mediterranean) have disturbed this originally oligotrophic aquatic system. The nutrient input into the lagoon has triggered its eutrophication, leading to dystrophic crises and mass mortality events for aquatic biota, transforming it into one of the most eutrophication- impacted transitional waters in the Mediterranean basin. In this study, we applied a fish-based indicator to assess the ecological quality of shallow waters under different eutrophication-mediated environmental stress scenarios (from pre-eutrophic reference periods to critical eutrophic periods), as well as to explore the role of confinement (i.e., water renewal time) and shoreline anthropogenic pressure as factors modulating the indicator response. Despite the high magnitude of the eutrophication impact on the lagoon, the ecological quality of the shallow waters decreased only slightly after the mass mortality events. The level of confinement also had slight effects on the ecological quality of the most confined shallow areas in the summer during eutrophic periods. Hence, shallow waters could play a critical role as refuge habitats, both for fish assemblages and other aquatic taxa, by buffering euxinic conditions during eutrophication processes.”. In fact, shallow waters could act as critical habitats, allowing for the recolonisation of aquatic biota from more impacted areas in the lagoon. This attribute further reinforces the need to properly manage and protect the shoreline areas of transitional waters, particularly under eutrophication scenarios.