@article {9640, title = {Accounting for variability in life-history traits for the definition of amphidromous goby fry fisheries closure periods}, journal = {Cybium}, volume = {47}, year = {2023}, month = {10/2023}, pages = {391-399}, abstract = {Amphidromous goby fry (post-larvae and young juveniles) are traditionally fished when they arrive in rivers after their larval development at sea. In Reunion Island (Indian Ocean) two species of amphidromous goby are mainly targeted by the fisheries: the endemic\ Cotylopus acutipinnis\ and the cosmopolitan\ Sicyopterus lagocephalus. Despite the lack of quantitative data on these fisheries, their impact on populations\ is expected to be important because the catches can represent several tonnes per year. Consequently, fishery regulation changes have been proposed that increase the duration of the existing fisheries closure period of two weeks in March. We developed an approach to identify key periods for fisheries closure, including assessment of the proposed management scenario and several alternative protection scenarios, based on the maximization of fry abundance and on the variability of four life-history traits: (i) fry size and (ii) age at arrival in rivers, (iii) the time the juveniles spend in river before maturation and (iv) their migration behaviour. This approach is in seeking to preserve a high level of phenotypic diversity, which is predicted to promote population resilience. We conducted a multiple-criteria decision analysis to rank 4096 alternatives of fisheries closure periods, ranging from zero to 12 months, based on their propensity to maintain fry abundance and life history trait diversity. Finally, according to the type of fisheries closure period (discontinuous or continuous) and the proportion of annual abundance and variability of life-history traits preserved during the period (50\% or 75\%), we propose four different fisheries closures lasting from six to nine months.}, keywords = {amphidromy, Bichiques, Conservation, diadromy, Indian Ocean, Management, recruitment}, doi = {10.26028/cybium/2023-018}, url = {https://sfi-cybium.fr/fr/accounting-variability-life-history-traits-definition-amphidromous-goby-fry-fisheries-closure}, author = {Lagarde, Rapha{\"e}l and Valade, Pierre and Teichert, Nils} } @article {7397, title = {Structure of small tropical island freshwater fish and crustacean communities: A niche-or dispersal-based process?}, journal = {Biotropica}, year = {2020}, month = {Jan-10-2021}, abstract = {Determining the relative importance of niche- and dispersal-based processes in the structuring of animal communities is central in ecology. Freshwater fish and crustacean communities of small tropical islands can bring new insights for understanding these processes as all their species present a pelagic larval stage which gives them important dispersal capacities. Consequently, we hypothesized that dispersal-based process may be preponderant for structuring these communities from the regional to the local, that is, survey site, scales. Gradient forest analyses allowed us to model the effect of 12 environmental variables on freshwater taxa abundances in two southwestern Indian Ocean islands: Mayotte (26 taxa) and Reunion (21). A total of 153 surveys in Mayotte and 266 in Reunion were used for building the models. Despite the strong heterogeneity of environmental conditions between the two islands, the main factors structuring freshwater fish and crustacean communities in both islands were the elevation and the slope of the sites. The observed structure appeared more pronounced for predatory species than for primary consumers and omnivores. As predators generally have limited locomotor capacities, it is concluded that dispersal-based process structures these communities not only at large geographical scales but also at the intra-watershed scale, by limiting the inland penetration (or dispersion) of species in relation to their locomotor capacities. However, more knowledge concerning ecological traits and taxonomic status of many species is needed to confirm this assumption.
}, keywords = {abundances, diadromy, environmental gradients, Migration, taxonomic richness, western Indian Ocean}, issn = {0006-3606}, doi = {10.1111/btp.12865}, url = {https://onlinelibrary.wiley.com/doi/10.1111/btp.12865}, author = {Lagarde, Rapha{\"e}l and Teichert, Nils and Valade, Pierre and Ponton, Dominique} } @article {4584, title = {Specific gravity and migratory patterns of amphidromous gobioid fish from Okinawa Island, Japan}, journal = {Journal of Experimental Marine Biology and Ecology}, volume = {486}, year = {2017}, pages = {160-169}, abstract = {

Amphidromy is a diadromous life history pattern where fish spawn in freshwater, and their larvae drift downstream to the sea; the larvae develop in marine environments then migrate back in rivers to grow and reproduce. Two amphidromous types with different life history characteristics, such as egg and larval sizes, exist. To understand the ecology and early life history of amphidromous gobioid fish, six species from Okinawa Island were selected{\textemdash}two large egg-type species (Rhinogobius similis and Tridentiger kuroiwae) and four small egg-type species (Stiphodon percnopterygionus, Stenogobius sp., Sicyopterus lagocephalus, and Eleotris acanthopoma). The migratory pattern of four of these species was confirmed using otolith Sr:Ca and Ba:Ca ratios combined with water chemistry analysis. Although these species showed amphidromous migratory patterns, the timing of migration from estuarine to freshwater habitats was species-specific. The large egg-type, R. similis, showed three different migratory patterns: a long marine larval phase with a relatively fast migration from estuarine to freshwater habitats, a short marine larval phase with a relatively fast migration, and a gradual migration. Similar patterns of a long and fast migration or a gradual migration were seen in T. kuroiwae; however, the two small eggtype species, Sti. percnopterygionus and Stenogobius sp., showed rapid migration to freshwater after entering the river. To estimate larval ecology in the sea, ontogenetic changes in specific gravity (SG) were examined in all species. The SG was measured day and night for 1{\textendash}5 days until settlement in R. similis and T. kuroiwae, and until 10 days after hatching in the other species. The SG of all species ranged from 1.0138 to 1.0488, and varied among ontogenetic stages and between day and night and species. Larval SG was relatively similar between R. similis and T. kuroiwae, with low SG in the early stages and high SG after yolk absorption. During the late larval stages and until settlement, T. kuroiwae showed diel changes in SG, with higher SG during the day, whereas R. similis had a relatively constant pattern. The diel changes of T. kuroiwae larvae suggest different activity during the day and at night (e.g. diel vertical migration). In the four small egg-type species, SG was high at hatching and decreased thereafter, not showing large diel changes. The results suggest that sympatric amphidromous gobioid species have various early life histories that may be influenced by several larval traits, including SG.

}, keywords = {Buoyancy, diadromy, Early life history, Migratory history, otolith, Specific gravity}, author = {Iida, Midori and Masashi Kondo and H{\'e}l{\`e}ne Tabouret and Maeda, Ken and P{\'e}cheyran, C and Atsushi Hagiwara and Philippe Keith and Katsunori Tachihara} } @article {3722, title = {Amphidromy and marine larval phase of ancestral Gobioids Rhyacichthys guilberti and Protogobius attiti (Teleostei: Rhyacichthyidae).}, journal = {Marine and Freshwater Research}, volume = {65}, year = {2014}, pages = {776{\textendash}783}, abstract = {

Even if amphidromous fish species contribute most to the diversity of fish communities in the tropical insular
rivers, their biological cycle remain poorly known. For the first time, the otolith elemental composition and microstructure
of two ancestral gobioids, Rhyacichthys guilberti and Protogobius attiti, were investigated to describe their biological
cycle and pelagic larval duration (PLD). The otolith analysis using a femtosecond laser ablation coupled to an inductively
coupled plasma{\textendash}mass spectrometer (fs-LA-ICP-MS) revealed an amphidromous life history for R. guilberti and it
suggested a progressive habitat shift from a marine habitat to a freshwater environment for P. attiti. For the first time, an
endemic species, P. attiti, showed longer and more variable PLD (55.213.5 days) than did a widespread one
(R. guilberti: ,30 days). These results need to be confirmed by analysing more samples but suggest that factors other
than the PLD control endemism and dispersal processes. In association with this first description of the biological cycle for
both species, such an approach is a prerequisite for the management and conservation of both patrimonial species.

}, keywords = {diadromy, freshwater gobies, otolith microchemistry, tropical islands.}, author = {H{\'e}l{\`e}ne Tabouret and Tomadin, Marina and Taillebois, Laura and Iida, Midori and Clara Lord and P{\'e}cheyran, C and Philippe Keith} }