a b s t r a c tWe compared the distribution and seasonal fluctuations in the aquatic biota in relation to chemical and physical water variables in the Altiplano watersheds of the Ascot an, Carcote and Huasco salars; Chungar a and Cotacotani lakes; Isluga and Lauca Rivers and the Parinacota wetland. We sampled during the austral autumn-winter of 2006 and in the spring-summer of 2006-2007, using three sampling stations for each system. We used canonical correspondence analysis to establish relations between frequency of taxa and environmental variables.We demonstrate that the structure and composition of the aquatic biota in humid areas of the Altiplano is determined by physical and chemical variables of the water. The most relevant one is total nitrogen, which is also the limiting nutrient for phytoplankton production in tropical systems.Benthos and zooplankton showed significant associations with the set of environmental variables (Monte Carlo test, po0.05); however, the association was not significant for phytoplankton. Lake Chungar a showed the greatest variation in composition and abundance of zooplankton between autumn-winter and spring-summer, while in the Huasco salar the physical and chemical characteristics were related to the composition and abundance of the benthonic fauna. Thus, changes in the water volume of these systems would have repercussions in chemical and physical variables, altering the species assemblage and possibly the efficiency and stability of ecosystem functions.
SummaryPromoting conservation practices in agriculture to protect biodiversity of rare Mediterranean ecosystems is nowhere more critical than in Chile, where less than 2% of the Mediterranean region is formally protected. We used the theory of planned behaviour to assess what influences Chilean winegrowers’ conservation behaviour and tested whether a sustainability programme was effective. We compared winegrowers involved in the programme with a comparison group, using semi-structured interviews at 23 wineries to determine predictors of conservation practice adoption at vineyards. The intervention group had higher levels of conservation behaviour than the comparison group and practised integrated pest management and exotic species control more frequently. Managers’ views on conservation practices as doing ‘what is right’ with regards to nature and the environment were evident in both groups. However, programme winegrowers recognized more cultural benefits of nature and reported a broader spectrum of organizational and community stakeholder influence. Economic resources were perceived as a major barrier, as well as the lack of data connecting biodiversity conservation with wine quality and production. This study demonstrates the multidimensional nature of winegrowers’ motivations and barriers for adopting conservation practices, which is critical to addressing the significant challenges facing biodiversity conservation and the promotion of sustainable agricultural systems.
We explored the response to habitat desiccation in tadpoles of the warty toad Rhinella spinulosa in a manipulative field experiment. We built an artificial pond system with two desiccation levels (high and low) and populated with tadpoles at Gosner stage 25. Each treatment was replicated six times. We measured the survival, size and age at metamorphosis, development rate and hind limb length in metamorphs. The results showed that tadpoles from the high desiccation ponds accelerated their development, reaching metamorphosis at an earlier age than tadpoles from the low desiccation ponds. Survival, size at metamorphosis and hind limb length were not different between treatments. This experiment demonstrated that tadpoles of R. spinulosa accelerate their development in response to habitat desiccation. Such plasticity may allow them to avoid mortality in short duration ponds. No evidence for a trade-off between development time and size at metamorphosis was found in this experiment. We suggest that factors such as initial tadpole density and nutritional quality of food would contribute towards determining whether metamorphosis occurs at the developmental threshold or at a larger size.This study was funded by Proyecto FONDECYT 1061256. MMG is grateful for the financial support from the CONICYT fellowship. SAG (Servicio Agrı´ cola Ganadero) supplied collecting permits (Resolution number 3085/2000, 2105/2004 and 13/2006)
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