Browsing by Author "Rocha, Luiz A."
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- Ecological traits influencing range expansion across large oceanic dispersal barriers: insights from tropical Atlantic reef fishesPublication . Luiz, Osmar J.; Madin, Joshua S.; Ross Robertson, D.; Rocha, Luiz A.; Wirtz, Peter; Floeter, Sergio R.How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here, we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier (MAB) and the Amazon-Orinoco Plume (AOP). Generalized linear mixed-effects models indicate that predictors for successful barrier crossing are the ability to raft with flotsam for the deep-water MAB, non-reef habitat usage for the freshwater and sediment-rich AOP, and large adult-size and large latitudinal-range for both barriers. Variation in larval-development mode, often thought to be broadly related to larval-dispersal potential, is not a significant predictor in either case. Many more species of greater taxonomic diversity cross the AOP than the MAB. Rafters readily cross both barriers but represent a much smaller proportion of AOP crossers than MAB crossers. Successful establishment after crossing both barriers may be facilitated by broad environmental tolerance associated with large body size and wide latitudinal-range. These results highlight the need to look beyond larval-dispersal potential and assess adult-biology traits when assessing determinants of successful movements across marine barriers.
- Environmental and geographical drivers of reef fish beta diversity across the depth gradientPublication . Koivunen, Anna; Lopes da Cunha, Regina; Quimbayo, Juan P.; Otero-Ferrer, Francisco; Freitas, Rui; Mallmann, Antonia I. M.; Fauvelot, Cécile; Bramanti, Lorenzo; Rocha, Luiz A.; Pinheiro, Hudson T.The swift decline of coral reefs stands out as a significant biodiversity challenge confronting our generation, and mesophotic coral ecosystems (MCEs; reefs between 30 and 150 m) have been proposed as refuge habitats that may be less affected by climate change and human impacts compared to their shallow counterparts. However, MCEs are often distinct from shallow reefs, and studies assessing how marine biodiversity changes along the depth gradient and what factors can influence marine communities in MCEs are still scarce. Here, we conducted underwater visual censuses to evaluate how fish assemblages change among islands and environmental characteristics across the shallow to mesophotic depth gradient within the Cabo Verde Archipelago. Our results show that the beta diversity of reef fish assemblages was mainly driven by depth and environmental factors such as temperature and benthic variables. A consistent trend of increasing beta diversity from the shallow to the lower mesophotic zone was observed among the islands, with the lowest variation in species composition observed between the shallow (5-30 m) and upper (31-60 m) mesophotic depths. Lower species richness and higher turnover was observed within lower MCEs (61-85 m), suggesting saturation in fish richness at small scales, possibly a result of changes in microhabitat heterogeneity. Furthermore, the effect of geography was negligible, and local-scale environment characteristics were the main drivers of differences in species assemblages. Evidence suggests that increased fishing pressure on the most populated island may reduce the biogeographic influence on fish assemblages across the archipelago.