Aquatic Ecology and Ecotoxicology
research
Project description
Summary
Highaltitude tropical environments are currently facing the impact of solar radiation and increasing global temperature. Historically, they have also been affected by the input of high metal levels and acid waters coming from mining exploitation and natural leaching. Of particular interest are benthic communities inhabiting these streams, since they have evolved unique attributes to cope with inherent conditions to high altitude (e.g. low oxygen pressure). On the other hand, they are also able to adapt and survive to increased UV radiation, metal and acid conditions that are known to exert detrimental effects on aquatic biota by means of reactive oxygen species and disruption of metabolic functions. Tolerance to these toxicants is based mainly on the production of photoprotective pigments, antioxidant systems and metal-chelating proteins (e.g. metallothioneins, MT), compared to organisms living in pristine streams. Although these defenses, such adverse conditions can reduce benthic invertebrate abundance and species richness thus modifying community structure. Since high altitude poses a challenge for survival of benthic invertebrates, additional stressors such as acidic conditions, elevated metal levels and high UV-B radiation may also contribute to select tolerant communities. The aim of this thesis is to explore what adaptations are present in specialized benthic populations exposed to these extreme conditions in the Cordillera Blanca, in the Peruvian Andes, which represents the largest fraction of all tropical glaciers. Populations from 4000 and 3000m a.s.l. and from polluted and clean streams will be compared for levels of pigments, antioxidant capacity and MT. Also, comparisons among populations during rainy and dry seasons may be explored since water regimes modify the exposition to stressors. Differences among these physiological traits will be also evaluated under laboratory conditions after exposure to individual and combined stressors to corroborate field observations. The statistical analysis of data will allow identifying the main elements affecting tolerant benthic fauna and the physiological responses underlying such tolerance at high altitudes. Furthermore, this study may allow evaluating the impacts of global change on the tropical Andes, which are considered a highly susceptible ecoregion.