Tropical essentials habitats for juvenile fish assemblages in insular ecosystems


Lucie NUNEZ -


French Polynesia (Moorea), Mayotte, Philippines




This multi-year project (2023-2026) aims to understand and conserve subtropical coastal habitats that are vulnerable to global change, but yet essential to a number of teleost species as they play a nursery role for those species. It comes to compensate the lack of knowledge on the identification and location of priority essential habitats in the subtropics, the conservation of which is a key focus of public policies.

It meets 4 main objectives: (1)  identify essential habitats (nurseries) and their juvenile teleost assemblages within the mosaic of coral reef habitats and associated ecosystems (particularly mangroves and phanerogam meadows); (2) understand the impacts of anthropogenic factors (direct or indirect transformation of habitats) on juvenile assemblages and therefore the nursery function of these essential habitats; (3) assess the connectivity between nursery habitats and adult habitat; and finally (4) locate these habitats, quantify their availability within the study area, estimate their vulnerability, evaluate their consideration by current management measures and thus advise on their possible optimisation (e.g. design of strong protection zones)


3D structure given by reef habitats confers refuges and food to juvenile fish © Olivier Bianchimani – Septentrion Environnement


Fish nursery habitats are now at the center of public policies, as they are essential for adult population renewal. Various studies carried out in the western Mediterranean have revealed the diversity of nursery habitats used by juvenile fish (Cheminée et al., 2021; Cuadros, 2015; Harmelin-Vivien et al., 1995). Within underwater landscapes various habitats (seagrass beds, rocks, etc.) will therefore be complementary to respond to the several ecological needs of various species. Their coastal location makes them particularly sensitive to anthropogenic pressures, including coastal development and climate change, which leads to their transformation and/or loss. Several studies agree that this habitat transformation can alter their function as nurseries for teleost fish (Cheminée et al., 2017).

The same conservation issues are seen in subtropical environments where the impact of global change and species/habitat relationships have yet so far received little attention from the scientific community (Wilson et al., 2010). Several emblematic habitats of these regions, including coral reefs and mangroves, play the nursery role for many tropical teleosts, some of them having a  high economic and ecological interest like the parrotfish or trevallies (Mumby et al., 2004).

Thus, it seems essential to develop a greater understanding of the role of these essential habitats in order to achieve long-term conservation of marine ecosystems and appropriated management of these habitats (Wilson et al., 2010).

Study sites and local partners

The study areas identified following various discussions with the scientific and technical partners are : French Polynesia (Moorea and Bora-Bora), Mayotte, Philippines.

Scientific and technical partners