Macroinvertebrate community dynamics in a temperate European Atlantic river. Do they conform to general ecological theory? |
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Authors: | Mario álvarez-Cabria José Barquín and José Antonio Juanes |
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Institution: | (1) Instituto de Hidr?ulica Ambiental “IH Cantabria”, Grupo de Emisarios Submarinos e Hidr?ulica Ambiental, Universidad de Cantabria, Avda. de los Castros s/n, 39005 Santander, Spain |
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Abstract: | Spatial and temporal dynamics of macroinvertebrate communities have usually been linked to several environmental and anthropic
factors. The aim of this study is to elucidate how important are these factors in structuring macroinvertebrate communities
from temperate regions. Regarding the macroinvertebrate number of taxa, the Habitat Template Model, the Dynamic Equilibrium
Hypothesis and the Intermediate Disturbance Hypothesis will be tested in order to know how important the diversity of instream
elements and the hydrological disturbance frequency are in defining the macroinvertebrate taxonomic richness. Thus, the structure
and composition of macroinvertebrate communities were analysed in nine sites of the Pas River basin, a temperate Atlantic
basin in northern Spain, during winter, spring, summer and autumn 2005, together with water physicochemical and environmental
characteristics. Macroinvertebrate abundance increased downstream and during summer, probably favoured by lower hydraulic
stress and water organic enrichment. As predicts the Habitat Template Model, the macroinvertebrate number of taxa was related
to habitat heterogeneity. However, no clear relationship amongst macroinvertebrate richness and water quality was found. The
macroinvertebrate taxonomic richness did not correspond exactly with the Dynamic Equilibrium Hypothesis and the Intermediate
Disturbance Hypothesis because it was relatively high in the absence of hydrological disturbances (summer). Thus, disturbance
events may play a secondary role in determining the seasonal dynamic of the number of taxa. However, hydrological disturbances
can be considered the most important factors explaining the seasonal pattern of macroinvertebrate abundance. On the other
hand, spatial patterns of macroinvertebrate community structure and composition were mainly determined by resource availability,
hydraulic conditions, habitat heterogeneity and human alterations, whilst hydrological predictability and resource availability
might play a major role in determining seasonal dynamics. |
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