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<p>Juvenile fish condition is widely regarded as an indicator of nursery habitat quality and has become an important tool for fisheries management. Although the distribution and growth of grey mullets (Mugilidae) are known to vary along environmental gradients in Mediterranean coastal ecosystems, the extent to which these gradients influence juvenile physiological condition across contrasting nursery habitats remains poorly understood. We investigated the distribution, growth patterns and body condition of young-of-the-year individuals of five Mugilidae species (<i>Chelon auratus</i>,<i> Chelon ramada</i>,<i> Chelon labrosus</i>,<i> Chelon saliens</i> and <i>Mugil cephalus</i>) sampled seasonally over 14 months in two estuaries, one coastal lagoon and one marine beach in the south-western Mediterranean. Species distribution was analysed using canonical correspondence analysis, while habitat quality was assessed using length–weight relationships together with three complementary condition indices (Fulton’s K, Le Cren’s Kn and relative weight, Wrm). A total of 2,114 juveniles were collected, with <i>C. saliens</i> accounting for 46.9% of all individuals. Species composition differed markedly among habitats and seasons, and salinity had little influence compared with other environmental variables. Seasonal values of the allometric coefficient (<i>b</i>) ranged from 2.17 to 3.60 for <i>C. saliens</i>, 2.33 to 3.20 for <i>C. auratus</i>, 2.40 to 4.04 for <i>C. ramada</i>, 2.61 to 3.28 for <i>C. labrosus</i> and 2.67 to 4.29 for <i>M. cephalus</i>. Maximum Fulton’s K varied seasonally, whereas Kn was generally greater than 1, indicating good condition across habitats. Multiple linear regression revealed species-specific relationships between seasonal K and environmental variables, while Kn and Wrm were strongly correlated (0.95 ≤ <i>r</i> ≤ 0.99) for all species. These findings show that integrating complementary condition indices with environmental characteristics improves the assessment of Mediterranean coastal nursery habitats and provides a valuable framework for habitat conservation, fisheries management and the identification of priority nursery areas.</p>

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Environmental Gradients Shape Habitat use and Juvenile Condition Across Mediterranean Coastal Nurseries: Evidence From Five Grey Mullet Species

  • 期刊论文

  • 发表日期：

    2026年7月16日

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  • Ali Becheker,
  • M. Hichem Kara,
  • Lamya Chaoui

摘要

Juvenile fish condition is widely regarded as an indicator of nursery habitat quality and has become an important tool for fisheries management. Although the distribution and growth of grey mullets (Mugilidae) are known to vary along environmental gradients in Mediterranean coastal ecosystems, the extent to which these gradients influence juvenile physiological condition across contrasting nursery habitats remains poorly understood. We investigated the distribution, growth patterns and body condition of young-of-the-year individuals of five Mugilidae species (Chelon auratus, Chelon ramada, Chelon labrosus, Chelon saliens and Mugil cephalus) sampled seasonally over 14 months in two estuaries, one coastal lagoon and one marine beach in the south-western Mediterranean. Species distribution was analysed using canonical correspondence analysis, while habitat quality was assessed using length–weight relationships together with three complementary condition indices (Fulton’s K, Le Cren’s Kn and relative weight, Wrm). A total of 2,114 juveniles were collected, with C. saliens accounting for 46.9% of all individuals. Species composition differed markedly among habitats and seasons, and salinity had little influence compared with other environmental variables. Seasonal values of the allometric coefficient (b) ranged from 2.17 to 3.60 for C. saliens, 2.33 to 3.20 for C. auratus, 2.40 to 4.04 for C. ramada, 2.61 to 3.28 for C. labrosus and 2.67 to 4.29 for M. cephalus. Maximum Fulton’s K varied seasonally, whereas Kn was generally greater than 1, indicating good condition across habitats. Multiple linear regression revealed species-specific relationships between seasonal K and environmental variables, while Kn and Wrm were strongly correlated (0.95 ≤ r ≤ 0.99) for all species. These findings show that integrating complementary condition indices with environmental characteristics improves the assessment of Mediterranean coastal nursery habitats and provides a valuable framework for habitat conservation, fisheries management and the identification of priority nursery areas.