Integrity of fluvial fish communities is subject to environmental gradients in mountain streams, Sierra de Aroa, north Caribbean coast, Venezuela

Abstract

We examined physical habitat and fish assemblages in rivers of the Aroa Mountains (Venezuela) with different levels of environmental protection due to the creation of Yurubí National Park within the drainage. We developed an Index of Biotic Integrity (IBI) and evaluated it using principal components analysis (PCA) and canonical correspondence analysis (CCA). Tributary rivers were divided into classes according to their origin (protected by the park) and physical characteristics of each, including substrate. Fishes were captured using standardized electrofishing. Fish communities showed greater species richness in heterogeneous habitat and protected rivers but overall abundance was higher in unprotected and impacted rivers. The IBI was sensitive to these differences and the scores were higher in protected rivers. The IBI detected degree of disturbance of fish communities without direct consideration of habitat parameters measured. The PCA revealed a gradient in substrate heterogeneity. Similarly, CCA revealed differences in fish assemblage composition along the environmental gradient and that varied with protection status of the river. The relationship between PCA and IBI scores was highly significant (r² = 0.61, P < 0.0001). The PCA and CCA analysis moderately validated the structure and predictability of IBI; but it is still necessary to refine the model and to extend its application for more time and over a wider area.<br>Foram avaliados o ambiente físico e as assembléias de peixes em rios das montanhas Aroa (Venezuela) com diferentes níveis de proteção ambiental devido a criação do Parque Nacional Yurubí nesta drenagem. Foi desenvolvido um Índice de Integridade Biótica (IBI), avaliado através da análise de componentes principais (PCA) e análise de correspondência canônica (CCA). Rios tributários foram divididos em classes, de acordo com sua origem (proteção pelo Parque) e características físicas, incluindo o substrato. Peixes foram capturados utilizando-se pesca-elétrica padronizada. As comunidades de peixes mostraram maior riqueza de espécies em habitats heterogêneos e rios protegidos, porém a abundância foi maior em áreas não protegidas e rios não impactados. O IBI foi sensível a estas diferenças e os escores foram mais elevados em rios protegidos. O IBI detectou o grau de distúrbio nas comunidades de peixes sem a consiedração direta dos parâmetros de habitat medidos. O PCA revelou um gradiente de heterogeneidade no substrato. De modo similar, a CCA revelou diferenças na composição da assembélia de peixes ao longo do gradiente ambiental que variou com o estatus de proteção do rio. A relação entre os escores de PCA e IBI foi altamente significativa (r² = 0.61, P < 0.0001). As análises de PCA e CCA validaram moderadamente a estrutura e a previsibilidade do IBI; porém, é necessário refinar o modelo e estender este aplicativo por mais tempo e área mais abrangente

Protected areas and freshwater biodiversity: a novel systematic review distils eight lessons for effective conservation

“…Human activities within protected areas can also generate disturbances that constrain biodiversity outcomes. This review recorded negative changes in river fish metrics within protected areas due to local disturbances from dredging, mining, and deforestation (Rodríguez‐Olarte et al., ). Chemical contamination from a pulp mill that triggered the disappearance of Brazilian waterweed, the food plant of black‐necked swan ( Cygnus melancoryphus ), caused high mortalities due to starvation as well as massive migration out of the protected area (González & Fariña, ).…”

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“…The effective understanding of the attributes in fish communities and their consequent biotic integrity requires data with spatial and temporal amplitude in order to recognize the changes and the relations in the communities respect to disturbance gradients (Rodríguez-Olarte et al, 2006). Introductions of fish species are widespread in Turkish reservoirs and occur in all regions, which are suitable (Innal and Erk'akan, 2006).…”

Habitat characteristics and environmental parameters influencing fish assemblages of karstic pools in southern Mexico

“…Tilapia farming, water extraction, and other uses by local people, may have also contributed to the deterioration of water conditions, which can have a relevant effect on the biological patterns and ecosystem-level process (Snyder et al, 2003;Rodríguez-Olarte et al, 2006). Furthermore, the fragmentation of adjacent forests may have an impact on the adjacent fish community.…”