Assessing Land-use Effects on Water Quality, In-stream Habitat, Riparian Ecosystems and Biodiversity in Patagonian Northwest Streams

CONICET Laboratorio de Investigaciones en Ecología y Sistemática Animal-Universidad Nacional de la Patagonia San Juan Bosco, Argentina.
Science of The Total Environment (Impact Factor: 4.1). 01/2011; 409(3):612-24. DOI: 10.1016/j.scitotenv.2010.10.034
Source: PubMed


Changes in land-use practices have affected the integrity and quality of water resources worldwide. In Patagonia there is a strong concern about the ecological status of surface waters because these changes are rapidly occurring in the region. To test the hypothesis that greater intensity of land-use will have negative effects on water quality, stream habitat and biodiversity we assessed benthic macroinvertebrates, riparian/littoral invertebrates, fish and birds from the riparian corridor and environmental variables of 15 rivers (Patagonia) subjected to a gradient of land-use practices (non-managed native forest, managed native forest, pine plantations, pasture, urbanization). A total of 158 macroinvertebrate taxa, 105 riparian/littoral invertebrate taxa, 5 fish species, 34 bird species, and 15 aquatic plant species, were recorded considering all sites. Urban land-use produced the most significant changes in streams including physical features, conductivity, nutrients, habitat condition, riparian quality and invertebrate metrics. Pasture and managed native forest sites appeared in an intermediate situation. The highest values of fish and bird abundance and diversity were observed at disturbed sites; this might be explained by the opportunistic behavior displayed by these communities which let them take advantage of increased trophic resources in these environments. As expected, non-managed native forest sites showed the highest integrity of ecological conditions and also great biodiversity of benthic communities. Macroinvertebrate metrics that reflected good water quality were positively related to forest land cover and negatively related to urban and pasture land cover. However, by offering stream edge areas, pasture sites still supported rich communities of riparian/littoral invertebrates, increasing overall biodiversity. Macroinvertebrates were good indicators of land-use impact and water quality conditions and resulted useful tools to early alert of disturbances in streams. Fish and birds having a greater ability of dispersion and capacity to move quickly from disturbances would reflect changes at a higher scale.

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Available from: Cecilia Brand, May 05, 2014
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    • "During the recent decades, the loss of freshwater biodiversity has been accentuated mainly due to changes in land use from humanrelated activities (e.g., forestry and livestock or arable farming) that have resulted in habitat destruction, fragmentation and eutrophication (e.g., Encalada et al., 2010; Miserendino et al., 2011; Lunde and Resh, 2012). In particular, because of the economic benefit from the cellulose industry (Valdovinos, 2006), the replacement of native forest by plantations of exotic species (i.e., monocultures of conifers and eucalyptus) has been a widespread forestry practice all over the world (Hartley, 2002). "
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    ABSTRACT: Over the past few decades, land-use changes through conversion of global forest cover to exotic plantations is contributing to both habitat and biodiversity loss and species extinctions. To better understand human influences on ecosystem, we use diet composition from introduced Rainbow Trout Oncorhynchus mykiss as indicator of potential changes in the composition of stream-macroinvertebrates due to land use changes from native to exotic vegetation (eucalyptus plantations) in southern Chile. Water quality variables, aquatic macroinvertebrates and Rainbow Trout diet were studied in 12 sites from mountain streams located in two watersheds including one dominated by native riparian vegetation and the other dominated by exotic vegetation. As expected, richness and abundance of macroinvertebrates were clearly higher at sites in native forest than in those with exotic vegetation. Collector-gatherer was the most abundant functional feeding group, but there was no statistical difference in the functional composition between the two watersheds. Differences in in-stream macroinvertebrate availability was more higher correlated with changes in Rainbow Trout diets. Specifically, taxa consumed from the watershed dominated by native forests was higher than from the watershed with exotic vegetation. Additional environmental variables showed statistical differences between watersheds. The exotic vegetation sites had the highest concentrations of dissolved solids, suspended solids, nitrates, chlorides and sulphates. Our findings show that macroinvertebrate assemblage structure and trout diets can be altered by changes in riparian vegetation. The absence of specific macroinvertebrate taxa in streams with exotic vegetation was captured by the composition of trout diets. This suggest that Rainbow Trout diets can be a good biological indicator of land use practices and thus, diet can be used as a rapid and effective tool for evaluate environmental quality. Our findings provide insights about the design of aquatic monitoring programmes to improve detection of anthropogenic impacts in streams in South America and elsewhere.
    Ecological Indicators 01/2016; 60:655-667. DOI:10.1016/j.ecolind.2015.08.018 · 3.44 Impact Factor
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    • "Compared to CVA, at NyF, rainbow trouts positively selected a higher number of terrestrial species (Table 3). This difference between streams in the number of terrestrial prey selected could be explained, to some extent, by the higher riparian and littoral invertebrate richness registered at NyF (Miserendino et al. 2011). "
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    ABSTRACT: Background: It is well known that fish predation alters ecosystem processes by top-down effects. Salmonids are described as aggressive, visually and size-selective predators. Thus, prey selection by the non-native rainbow trout was examined on a seasonal basis at two streams: Nant y Fall (NyF) and Cabeza de Vaca (CVA) at Patagonia, a region where this kind of information is lacking. Results: The benthos density at NyF was higher than that at CVA, and at both streams, riffles supported higher macroinvertebrate densities than pools. The diet of trouts from both streams was dominated by aquatic macroinvertebrates, was diverse, and was varied seasonally. The individuals represented in the stomach contents were among the largest available at the streams. Diet diversity peaked during spring at NyF and during summer at CVA, whereas at both streams, the niche width peaked during spring. Prey selectivity varied seasonally. The selected preys included both aquatic (Gasteropoda, Crustacea, Plecoptera, Trichoptera, Ephemeroptera, Coleoptera, Diptera, and Odonata) and terrestrial organisms (adult dipterans, Oligochaeta, Araneae, Homoptera, Hymenoptera, Orthoptera, and Hemiptera). Some infaunal invertebrates like oligochaetes and some small Coleoptera and Diptera larvae (mainly Chironomidae) were not selected by trouts. Conclusions: Despite of the overall dominance of trichopteran species, the composition of the diet of the rainbow trout varied seasonally. This fish positively selected both aquatic and terrestrial organisms. We observed that in both streams, trouts consumed the larger individuals available in those environments.
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    • "These riparian forests have been shown to (1) filter pesticides, sediments, and nutrients that are transported by rainfall, run-off, and groundwater flow processes (Boothroyd et al., 2004; Baker et al., 2006; Yamada et al., 2007); (2) maintain aquatic biota and stream ecosystems through temperature and flow regulation (Arismendi et al., 2013); (3) contribute to bank stabilization, large woody debris supply to the channel, and shading effect on streams (Brosofske et al., 1997; Lindenmayer and Franklin, 2002; Medina-Vogel et al., 2003); and (4) maintain biodiversity, including mammals (e.g. river otter, Medina-Vogel et al., 2003), flora (Gregory et al., 1991; Naiman et al., 1998), and macroinvertebrates (Mancilla et al., 2009; Miserendino et al., 2011). Forest vegetation is also one of the sources of dissolved organic carbon in runoff (Bishop et al., 1994) and a source of organic matter to stream channels (Dosskey et al., 2010). "
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