What are the main local drivers determining richness and fishery yields in tropical coastal fish assemblages?

ABSTRACT Seasonal ecological effects caused by temperature and photoperiod are typically considered minimal in the tropics. Nevertheless, annual climate cycles may still influence the distribution and abundance of tropical species. Here, we investigate whether seasonal patterns of precipitation and wind speed influence the structure of coastal fish assemblages and fishing yields in northeast Brazil. Research trips were conducted during the rainy and dry seasons using commercial boats and gear to sample the fish community. Diversity was analyzed using abundance Whittaker curves, diversity profiles and the Shannon index. Principal Component Analysis (PCA) was used to analyze associations between the abundance of species and various environmental variables related to seasonality. A total of 2,373 fish were collected, representing 73 species from 34 families - 20 of which were classified as both frequent and abundant. Species richness was greater and more equitable during the rainy season than the dry season - driven by changes in the precipitation rather than to wind speed. Species diversity profiles were slightly greater during the rainy season than the dry season, but this difference was not statistically significant. Using PCA was identified three groups of species: the first associated with wind speed, the second with precipitation, and the third with a wide range of sampling environments. This latter group was the largest and most ecologically heterogeneous. We conclude that tropical coastal fish assemblages are largely influenced by local variables, and seasonally mediated by annual changes related to precipitation intensity and wind speed, which in turn influences fishery yields

Data from: Response of Prochilodus nigricans to flood pulse variation in the central Amazon

The influence of the flood pulse on fish populations has been posited, but infrequently tested or quantified. Here, we tested the effect of habitat on population size, using Prochilodus nigricans as a case study species. Floodplain habitat was based on the littoral zone area occupied by P. nigricans to feed. The magnitude of this habitat in each hydrological year, the moving littoral (ML), was expressed as the sum of daily littoral areas during the advancing flood pulse, using satellite-based passive microwave data. Annual population size was estimated by age-class, using a dynamic age-structured model (MULTIFAN-CL) based on catches, effort, and fish length frequencies from the Manaus-based fishery over 12.75 years. The principal null hypothesis was that ML, using three lag times, had no effect on population size of a single age class of P. nigricans. The population size at 29 months of age was positively related (P=0.00030) to floodplain habitat (ML) earlier in the same year, when the fish were 21-27 months old. The result implies a density-dependent relationship for the population with respect to its feeding habitat. Potential mechanisms governed by flood pulse variation and habitat quality for this and other species utilizing floodplain habitats are discussed

LittoralVars

see READM

Manaus Fisheries data

see READM

Drawdown factor D

see READM

Genomic methods reveal independent demographic histories despite strong morphological conservatism in fish species

Human overexploitation of natural resources has placed conservation and management as one of the most pressing challenges in modern societies, especially in regards to highly vulnerable marine ecosystems. In this context, cryptic species are particularly challenging to conserve because they are hard to distinguish based on morphology alone, and thus it is often unclear how many species coexist in sympatry, what are their phylogenetic relationships and their demographic history. We answer these questions using morphologically similar species of the genus Mugil that are sympatric in the largest coastal Marine Protected Area in the Tropical Southwestern Atlantic marine province. Using a sub-representation of the genome, we show that individuals are assigned to five highly differentiated genetic clusters that are coincident with five mitochondrial lineages, but discordant with morphological information, supporting the existence of five species with conserved morphology in this region. A lack of admixed individuals is consistent with strong genetic isolation between sympatric species, but the most likely species tree suggests that in one case speciation has occurred in the presence of interspecific gene flow. Patterns of genetic diversity within species suggest that effective population sizes differ up to two-fold, probably reflecting differences in the magnitude of population expansions since species formation. Together, our results show that strong morphologic conservatism in marine environments can lead to species that are difficult to distinguish morphologically but that are characterized by an independent evolutionary history, and thus that deserve species-specific management strategies

Supplementary Material: Response of Prochilodus nigricans to flood pulse variation in the central Amazon

Manaus market data processing; MULTIFAN-CL analysis; Supplementary Table S

Artisanal Fisheries Research: A Need for Globalization?

Given limited funds for research and widespread degradation of ecosystems, environmental scientists should geographically target their studies where they will be most effective. However, in academic areas such as conservation and natural resource management there is often a mismatch between the geographic foci of research effort/funding and research needs. The former frequently being focused in the developed world while the latter is greater in the biodiverse countries of the Global South. Here, we adopt a bibliometric approach to test this hypothesis using research on artisanal fisheries. Such fisheries occur throughout the world, but are especially prominent in developing countries where they are important for supporting local livelihoods, food security and poverty alleviation. Moreover, most artisanal fisheries in the Global South are unregulated and unmonitored and are in urgent need of science-based management to ensure future sustainability. Our results indicate that, as predicted, global research networks and centres of knowledge production are predominantly located in developed countries, indicating a global mismatch between research needs and capacity

Unraveling the Mugil curema complex of American coasts integrating genetic variations and otolith shapes

The white mullet, Mugil curema, is a commercially important species in coastal areas, with a large phenotypic variability and genetic dissimilarity among populations throughout its distribution. For management purposes it is important to determine whether the morphological variability reflects the genetic differences among groups. This study evaluates whether the genetic differentiation in Mugil curema is reflected in the otolith shape on a large geographic scale in the Neotropical Atlantic and the Mexican Pacific. We analyzed the COI (Cytochrome Oxidase I) gene polymorphism as a marker and followed the otolith contour-based Fourier analysis as a morphometric method. Seven locations were studied, four in coastal lagoons of the Gulf of Mexico, one in the Mexican Pacific, one in the Caribbean Sea at Nueva Esparta, Venezuela and one in San Antonio Lagoon, Brazil. The genetic divergence accounted by the COI and the morphological differentiation in M. curema otoliths did not, in general, present cross-scale patterns, and the variability of otolith shapes was not reflected in the mitochondrial genetic variability. Other molecular methods could potentially reveal genetic differences. In particular, the variability in otolith shape among the Gulf of Mexico individuals may indicate that local divergences are accumulated in the otoliths, reflecting a possible interaction effect between local and regional drivers that is not evidenced at the genetic level.Fil: Ibañez, Ana. Universidad Autónoma del Estado de México; MéxicoFil: Rangely, Jordana. Universidade Federal de Alagoas; BrasilFil: Ávila Herrera, Lizette. Universidad Autónoma del Estado de México; MéxicoFil: da Silva, Victor E.L.. Universidade Federal de Alagoas; BrasilFil: Pacheco Almanzar, Eloisa. Universidad Autónoma del Estado de México; MéxicoFil: Neves, Jessika M.M.. Universidade Federal de Alagoas; BrasilFil: Avigliano, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Callicó Fortunato, Roberta Glenda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Fabré, Nidia N.. Universidade Federal de Alagoas; Brasi