Aquatic biodiversity across a hydroperiod gradient of lakes, ponds, and wetlands in Torres del Paine National Park, Chile (original) (raw)
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Ecological Engineering, 2019
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Anales del Instituto de la Patagonia, 2006
Southern South America is known globally for its remote and rugged landscapes, which include one of Chile's largest national park: Alberto De Agostini. The singular nature of this area, however, is also found in is flora and fauna. The recent designation of Magellanic Sub-Antarctic Forests as one of the world's last wilderness areas propelled us to question whether there was detailed evidence for this classification in the Tierra del Fuego portion of the De Agostini Park. Therefore, in January 2004 and 2005 boat-based expeditions were carried out around the south-west portion of Tierra del Fuego Island, as well as adjacent islands south of the Beagle Channel. Their purpose was to evaluate the current state of the park's natural resources and to create a baseline of physical, chemical, biological and ecological information that can be used in the administration, conservation and future research of this area. We utilized a watershed analysis approach, examining vegetation cover, habitat type and disturbance. Along the major watercourse of each basin, we quantified the presence of exotic species, water quality and the aquatic macroinvertebrate assemblage.
Heterogeneity of fresh-water Patagonia ecosystems
Ecologia Austral
The wide diversity of Patagonian freshwater ecosystems may be classified into three groups: glacial Andean lakes, Extra-andine closed depressions, and rivers and man-made lakes. We here analysed the biotic structure of Patagonian lentic and lotic ecosystems. We focus on the effect of both abiotic (climate, water composition, etc.) and biotic factors (competition, predation) on species diversity and composition of these communities. Zooplankton (rotifers and copepods) and macrobenthic insects (Plecoptera) were chosen as examples of the distribution patterns observed in lakes and rivers respectively. Rotifer species richness was explained by altitude, while species composition was related with conductivity. Three different rotifer assemblages were identified and associated with particular ranges of conductivity. In addition, the distribution of two rotifer genera, Keratella and Asplanchna, was related with biotic interactions (competition and predation). Crustacean size spectrum depended on visual fish predation. Plecoptera species richness decreased as a function of the stream order. Low stream order covered by Nothofagus forest showed the highest species number.
Freshwater Science, 2019
The use of ecoregions to classify stream and river environments has been extensively tested in North America and Europe, but few such studies have been conducted in South America. In this study we tested whether taxonomic richness, composition, and organism abundance within benthic macroinvertebrate assemblages were associated with ecoregions in northwestern Argentina at the genus and family levels. We included 3 ecoregions and their respective subecoregions in this study: the Yungas subtropical cloud forest, the Western Chaco subtropical dry forest, and the Monte xeric shrublands. We used nonmetric multidimensional scaling, analysis of similarity, and rank-abundance curves to assess how assemblages varied among ecoregions and subecoregions. We used principal components analysis to describe how environmental factors varied among sites and regions. Most aspects of invertebrate assemblages were associated with both ecoregions and subecoregions. The structure of the macroinvertebrate assemblages was generally concordant with ecoregional classification at the genus level, although concordance was not evident at the subecoregion level of resolution, especially for family-level data. The segregation of assemblages was most strongly related to environmental variables associated with topography and less strongly related to physiochemical variables. Our results confirm that ecoregions may effectively predict the invertebrate biota inhabiting streams in northwestern Argentina, but it was difficult to delineate discrete assemblages. Future work should assess the effectiveness of modeling approaches that would better account for the gradual changes in assemblage composition that occur along environmental gradients and test how well both classification and modeling approaches partition biotic variation in other parts of South America.
1. In Spain, national parks represent the mainstay of conservation polices and attempt to protect the most representative natural ecosystems. However, studies on the ecology and conservation of aquatic biodiversity within protected areas are still scarce. This study aimed at compiling an inventory of the macroinvertebrate families inhabiting the aquatic ecosystems of each mountainous Spanish national park (Sierra Nevada, Cabañeros, Ordesa, Picos de Europa, Aigüestortes and Monfragüe). The results were used to answer two questions: (i) Which environmental variables are related to macroinvertebrate composition and richness in these protected ecosystems? (ii) Which taxon or group of taxa could act as biodiversity surrogates?
Diversity
The analysis of functional diversity has shown to be more sensitive to the effects of natural and anthropogenic disturbances on the assemblages of aquatic macroinvertebrates than the classical analyses of structural ecology. However, this ecological analysis perspective has not been fully explored in tropical environments of America. Protected Natural Areas (PNAs) such as biosphere reserves can be a benchmark regarding structural and functional distribution patterns worldwide, so the characterization of the functional space of biological assemblages in these sites is necessary to promote biodiversity conservation efforts. Our work characterized the multidimensional functional space of the macroinvertebrate assemblages from an ecosystemic approach by main currents, involving a total of 15 study sites encompassing different impact and human influence scenarios, which were monitored in two contrasting seasons. We calculated functional diversity indices (dispersion, richness, divergence...
Journal of Limnology, 2014
Environmental variables and benthic macroinvertebrate assemblages were spatially and seasonally examined over two consecutive years (2000-2002) along a glacier and snowmelt river in the central-west of Argentina where lies the highest peak in America, Mount Aconcagua (6956 m elevation). The goal was to assess seasonal and altitudinal variability in benthic community structure and to define whether physical-chemical variables affect distribution of aquatic insects. The Mendoza River basin was characterised by high variability in flow and transparency, high conductivity, hard calcium sulphate water, neutral and alkaline pH, and dominant substrate composed of small blocks, cobbles, pebbles, and sand-silt. Richness of invertebrates was low, with the lowest taxonomic richness being recorded at the mouth. The dominant group with highest taxonomic richness was Diptera, although caddisflies, mayflies, beetles, and stoneflies were present. Seasonal and spatial variations in biotic and abiotic variables were detected. Maximal densities and taxonomic richness were recorded in autumn and winter. From Modified Morisita's Cluster analysis it was found that the system is divided into two groupings of sites related to each other by faunal composition. INDVAL revealed species turnover along the altitudinal gradient of some taxa: Andesiops, Massartellopsis, Edwarsina, Chelifera, and Ceratopogonidae had preference for the headwaters (2835-2425 m elevation), Smicridea murina and Baetodes for the lower section (1413-1085 m elevation), and Austrelmis for the middle and lower sections. The middle section (1846-1727 m elevation) was a transition area where taxa from the headwaters and the lower section coexisted. Generalised Linear Models evidenced that altitude was the major factor determining macroinvertebrate assemblages along the large arid Mendoza River and that the physical-chemical variables that most influenced variation in community structure were: transparency, bicarbonate concentration, pH and substrate type. Our results suggest that benthic macroinvertebrate structure and environmental variables are affected in different ways by seasonal and altitudinal variations.
NEW ZEALAND JOURNAL OF MARINE AND FRESHWATER RESEARCH, 2023
Herbivores in wetlands are key organisms that shape the structure and composition of wetland plant communities (algae and vascular plants). The detritus produced by herbivory contributes to nutrient cycling and provides important resources for other organisms in the ecosystem. Due to their importance, we decided to survey a set of 12 seasonal wetlands located in Andean Patagonian forests. We registered the biotic and abiotic variables of each wetland and the diversity and abundance of herbivores. We found two groups of wetlands: short hydroperiod and long hydroperiod. Despite this, the structure of the communities was not related to the hydroperiod length, abundance, or species composition. In particular, the abundance of herbivores was explained by chlorophyll, pH and dissolved oxygen, among others. Their diversity and abundance were (in decreasing order): rotifers, copepods, cladocerans, caddisflies, and amphibians. Probably, the species found in these wetlands are well adapted to different hydroperiod regimens and, even in short hydroperiods, can complete their life cycle. The results found here do not match with the model of hydroperiod gradient; however, other variables not measured here, such as diversity and abundance of aquatic plants or predation by invertebrates, could impact the composition and abundance of herbivores in these wetlands.
Amphibia-Reptilia, 2010
This constitutes the first study of anuran fauna composition of an artificial permanent water reservoir, in a semiarid ecosystem of San Luis. Species richness, relative abundance, spatial distribution and pattern of summer activity were estimated in the anuran community of the Embalse La Florida, an artificial water reservoir in the semiarid central region of the sierras of San Luis, Argentina. This reservoir represents one of the few sources of water available for reproduction and early development of amphibian species in the zone. We identified anurans using call surveys during two summers at fifteen sites, belonging to four zones around the shorelines of the reservoir. Eight amphibian species (Rhinella arenarum, Melanophryniscus stelzneri, Leptodactylus bufonius, Leptodactylus mystacinus, Odontophrynus americanus, Odontophrynus occidentalis, Pleurodema tucumanum and Hypsiboas cordobae) were recorded at the shores of the embalse. The highest species richness (seven) was detected in the preserve located on the north shore. Species richness analyzed by month or survey was not correlated with weather variables. The highest relative abundance of anurans was detected at the highly modified campsites area, which may provide stable food and refugia. Relative abundance of all anuran species was positively correlated with precipitation. This permanent water reservoir may act as an important site of amphibian fauna concentration, which is important to monitor and preserve.
Community structure of invertebrate fauna in Central Chilean Rivers
Acta Limnologica Brasiliensia, 2019
Aim River systems of Central Chile are short, steep and fast flowing. They are characterized by discharge regimes dominated by rainfall and snowmelt. Invertebrate fauna is highly endemic. This study aimed to describe the community structure of invertebrate in eight river systems in Central Chile (33-39°S) using species co-occurrence and niche sharing null models. Methods Invertebrate samples were collected from Central Chilean rivers (33-39°S), data were analyzed co-occurrence species and niche sharing null models for determine potential structuring patterns. Results The results revealed the presence of non-structured patterns in co-occurrence considering each site as well as all sites, that is most probably an effect of presence of many repeated species in the studied sites. Furthermore, we found the existence of niche overlap due to interspecific competition at each site and among all sites. The results obtained from these river systems corroborate observations from Chilean Patago...