Environmental Quality and Aquatic Invertebrate Metrics Relationships at Patagonian Wetlands Subjected to Livestock Grazing Pressures

Abstract

Livestock grazing can compromise the biotic integrity and health of wetlands, especially in remotes areas like Patagonia, which provide habitat for several endemic terrestrial and aquatic species. Understanding the effects of these land use practices on invertebrate communities can help prevent the deterioration of wetlands and provide insights for restoration. In this contribution, we assessed the responses of 36 metrics based on the structural and functional attributes of invertebrates (130 taxa) at 30 Patagonian wetlands that were subject to different levels of livestock grazing intensity. These levels were categorized as low, medium and high based on eight features (livestock stock densities plus seven wetland measurements). Significant changes in environmental features were detected across the gradient of wetlands, mainly related to pH, conductivity, and nutrient values. Regardless of rainfall gradient, symptoms of eutrophication were remarkable at some highly disturbed sites. Seven invertebrate metrics consistently and accurately responded to livestock grazing on wetlands. All of them were negatively related to increased levels of grazing disturbance, with the number of insect families appearing as the most robust measure. A multivariate approach (RDA) revealed that invertebrate metrics were significantly affected by environmental variables related to water quality: in particular, pH, conductivity, dissolved oxygen, nutrient concentrations, and the richness and coverage of aquatic plants. Our results suggest that the seven aforementioned metrics could be used to assess ecological quality in the arid and semi-arid wetlands of Patagonia, helping to ensure the creation of protected areas and their associated ecological services.

Livestock disturbances in Mediterranean temporary ponds: A mesocosm experiment with sheep manure and simulated trampling

“…Colonizing species (macroinvertebrates) were unaffected by livestock treatments, but richness and density were higher in agricultural ponds than forest ponds. This contrasts with other studies that have shown either a positive (Davis & Bidwell, 2008;Marty, 2005) or a negative (Bouahim et al, 2010;Davidson et al, 2017;Epele & Miserendino, 2015;Foote & Hornung, 2005) effect of grazing on the colonisation of ponds by macroinvertebrates. As these taxa arrived in mesocosms from the surrounding landscape, habitat choice becomes an important factor in their distribution and abundance (e.g.…”

“…Similar correlations have been previously observed (e.g. Epele & Miserendino, 2015) and may have resulted from the effects of eutrophication (Gulis, Ferreira, & Graça, 2006;Scheffer, 1990) or macrophyte facilitation and inhibition of invertebrates (De Szalay & Resh, 2000;Kneitel et al, 2017) in aquatic communities.…”

“…Similar negative effects have been found in other freshwater wetlands (e.g. Epele & Miserendino, ) and in a recent meta‐analysis of livestock effects in salt marshes (Davidson et al., ). Trampling may have created more homogeneity in habitat structure by the loss of microhabitats, which decreased species richness (Ross, ; Stein et al., ).…”

“…Bagella et al, 2010;Bouahim et al, 2010;Boughton, Quintana-Ascencio, Bohlen, Fauth, & Jenkins, 2016;Marty, 2005;Pyke & Marty, 2005;Rhazi, Rhazi, Grillas, & El Khyari, 2006). For example, livestock grazing can vary along an intensity gradient (Davidson et al, 2017;Epele & Miserendino, 2015), resulting in detrimental or beneficial effects on pond biodiversity (Bouahim et al, 2010;Davidson et al, 2017;Epele & Miserendino, 2015;Marty, 2005;Schmutzer et al, 2008).…”

Aquatic biodiversity across a hydroperiod gradient of lakes, ponds, and wetlands in Torres del Paine National Park, Chile

“…The use of "reference conditions" has been repeatedly employed as a strategy for managing aquatic communities (Reynoldson et al 1997) and includes documenting the composition of aquatic communities under pristine conditions along gradients of physical and biological conditions (Wright, 1995;Marchant et al 1997;Snodgrass et al 2000). Once we understand how species composition varies with changes in natural gradients, we can predict future changes in biodiversity as the landscape becomes altered by human intervention (Burroni et al 2011, Epele & Miserendino, 2015, 2016 . In this way, we can separate changes in biodiversity due to natural changes in the landscape from humaninduced changes in the landscape (Snodgrass et al 2000).…”