Determinants of reef fish assemblages in tropical Oceanic islands

Diversity patterns are determined by biogeographic, energetic, and anthropogenic factors, yet few studies have combined them into a large‐scale framework in order to decouple and compare their relative effects on fish faunas. Using an empirical dataset derived from 1527 underwater visual censuses (UVC) at 18 oceanic islands (five different marine provinces), we determined the relative influence of such factors on reef fish species richness, functional dispersion, density and biomass estimated from each UVC unit. Species richness presented low variation but was high at large island sites. High functional dispersion, density, and biomass were found at islands with large local species pool and distance from nearest reef. Primary productivity positively affected fish richness, density and biomass confirming that more productive areas support larger populations, and higher biomass and richness on oceanic islands. Islands densely populated by humans had lower fish species richness and biomass reflecting anthropogenic effects. Species richness, functional dispersion, and biomass were positively related to distance from the mainland. Overall, species richness and fish density were mainly influenced by biogeographical and energetic factors, whereas functional dispersion and biomass were strongly influenced by anthropogenic factors. Our results extend previous hypotheses for different assemblage metrics estimated from empirical data and confirm the negative impact of humans on fish assemblages, highlighting the need for conservation of oceanic islands.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes

Copyright: © 2011 Mora et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas

Influence of Neonatal Hypothyroidism on Hepatic Gene Expression and Lipid Metabolism in Adulthood

Thyroid hormones are required for normal growth and development in mammals. Congenital-neonatal hypothyroidism (CH) has a profound impact on physiology, but its specific influence in liver is less understood. Here, we studied how CH influences the liver gene expression program in adulthood. Pregnant rats were given the antithyroid drug methimazole (MMI) from GD12 until PND30 to induce CH in male offspring. Growth defects due to CH were evident as reductions in body weight and tail length from the second week of life. Once the MMI treatment was discontinued, the feed efficiency increased in CH, and this was accompanied by significant catch-up growth. On PND80, significant reductions in body mass, tail length, and circulating IGF-I levels remained in CH rats. Conversely, the mRNA levels of known GH target genes were significantly upregulated. The serum levels of thyroid hormones, cholesterol, and triglycerides showed no significant differences. In contrast, CH rats showed significant changes in the expression of hepatic genes involved in lipid metabolism, including an increased transcription of PPARα and a reduced expression of genes involved in fatty acid and cholesterol uptake, cellular sterol efflux, triglyceride assembly, bile acid synthesis, and lipogenesis. These changes were associated with a decrease of intrahepatic lipids. Finally, CH rats responded to the onset of hypothyroidism in adulthood with a reduction of serum fatty acids and hepatic cholesteryl esters and to T3 replacement with an enhanced activation of malic enzyme. In summary, we provide in vivo evidence that neonatal hypothyroidism influences the hepatic transcriptional program and tissue sensitivity to hormone treatment in adulthood. This highlights the critical role that a euthyroid state during development plays on normal liver physiology in adulthood

Elimination of radiocontrast agent Diatrizoic acid from water by electrochemical advanced oxidation: kinetics study, mechanism and mineralization pathway

International audienc

Elimination of radiocontrast agent Diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process.

International audienc

Elimination of radiocontrast agent Diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process.

International audienc

Projeção de mudanças na temperatura superficial do mar do Golfo da Califórnia e efeitos sobre a abundância e distribuição de espécies recifais

El Golfo de California es una zona de importancia por su alta biodiversidad y por ser clave para las pesquerías artesanales en México. Existe preocupación de las amenazas que existen sobre él, como el calentamiento global, que ha causado cambios en las comunidades. Por esto, se pretendió estimar el posible impacto del incremento de la temperatura oceánica sobre especies claves. Se estimaron los efectos potenciales del incremento de la temperatura sobre especies arrecifales. Para realizar esta estimación, se obtuvo información de la temperatura superficial oceánica (NOAA), se construyó un modelo de tendencias de cambio de temperatura. Los datos biológicos se obtuvieron de censos visuales de seis regiones del Golfo entre el 2005 y el 2007. Posteriormente se realizó un modelo lineal por pasos (stepwise), con él se proyectaron cambios en las abundancias y distribución de los organismos. Se estima que para el año 2050 la temperatura promedio se eleve 0.63°C; además, especies de importancia económica reducirán notablemente su abundancia al sur de los 25° N. Por último, modelamos la respuesta de 20 especies de peces más abundantes del Golfo para estimar cambios a escala comunitaria. La simulación indica desequilibrios en la función y estructura de las comunidades. El calentamiento oceánico provocará un desbalance en la composición y función ecológica de los ecosistemas por medio de alteraciones graduales en las abundancias de las especies. Por eso, la puesta en práctica de programas de monitoreo de las comunidades sería una herramienta fundamental para detectar efectos futuros del calentamiento.The Gulf of California is important because of its high biodiversity and because it is a key area for artisanal fisheries in Mexico. There are current concerns regarding threats to the Gulf, such as global warming, that have caused major changes in marine communities. Consequently, the aim of this study was to estimate the possible impact of increasing ocean temperature on key species.  Potential effects of such increase on reef species are thus estimated in this paper. In order to prepare this estimate, sea surface temperature (SST) was obtained from the NOAA database, and a temperature change trend model was constructed. Biological data was obtained from visual censuses of six regions within the Gulf between 2005 and 2007. A stepwise linear model was used to forecast potential changes in species abundance and distribution. It is estimated that by 2050 average temperature will increase 0.63°C, causing abundance of species of economic value to significantly decrease south of 25° N.  Finally, the response of the 20 most abundant fish species in the Gulf was modeled to estimate changes at community structure level. The simulation shows an imbalance in the function and structure of assemblages. Clearly, increasing sea temperature will bring an imbalance in the composition and the ecological function of the reef systems gradually changing the relative abundances of species. Therefore, the implementation of effective monitoring programs of communities would be an essential tool to detect future effects of global warming.O Golfo da Califórnia é uma zona de importância por sua alta biodiversidade e por ser decisivo para as pescarias artesanais no México. Existe uma preocupação das ameaças que existem sobre ele, como o aquecimento global que causou mudanças nas comunidades. Por isso, pretendeu-se estimar o possível impacto do aumento da temperatura oceânica sobre espécies chaves, como as espécies recifais. Para realizar esta estimativa, obteve-se informação da temperatura superficial oceânica (NOAA) e construiu-se um modelo de tendências de mudança de temperatura. Os dados biológicos foram obtidos de censos visuais de seis regiões do Golfo entre 2005 e 2007. Posteriormente, realizou-se um modelo lineal por passos (stepwise), com o qual se projetaram mudanças nas abundâncias e distribuição dos organismos. Estima-se que para o ano 2050 a temperatura média eleve 0.63°C; além disso, espécies de importância econômica reduzirão notavelmente sua abundância ao sul dos 25° N. Por último, modelamos a resposta de 20 espécies de peixes mais abundantes do Golfo para estimar mudanças a escala comunitária. A simulação indica desequilíbrios na função e estrutura das comunidades. O aquecimento oceânico provocará um desequilíbrio na composição e função ecológica dos ecossistemas por meio de alterações graduais nas abundâncias das espécies. Por isso, a execução na prática de programas de monitoramento das comunidades seria uma ferramenta fundamental para detectar efeitos futuros do aquecimento