22 research outputs found
Habitat heterogeneity on feeding habit of two sympatric and congeneric characidae fishes in two tropical reservoirs
Evaluating the role of predatory fish controlling the invasion of the Asian golden mussel Limnoperna fortunei
Monitoring strategies of stream phosphorus under contrasting climate-driven flow regimes
Climate and hydrology are relevant control factors determining the timing and amount of nutrient
losses from land to downstream aquatic systems, in particular of phosphorus
(P) from agricultural lands. The main objective of the study was to evaluate
the differences in P export patterns and the performance of alternative
monitoring strategies in streams under contrasting climate-driven flow
regimes. We compared a set of paired streams draining lowland
micro-catchments under temperate climate and stable discharge conditions
(Denmark) and under sub-tropical climate and flashy conditions (Uruguay). We
applied two alternative nutrient sampling programs (high-frequency composite
sampling and low-frequency instantaneous-grab sampling) and estimated the
contribution derived from point and diffuse sources fitting a source
apportionment model. We expected to detect a pattern of higher total and
particulate phosphorus export from diffuse sources in streams in Uruguay
streams, mostly as a consequence of higher variability in flow regime (higher
flashiness). Contrarily, we found a higher contribution of dissolved P in
flashy streams. We did not find a notably poorer performance of the
low-frequency sampling program to estimate P exports in flashy streams
compared to the less variable streams. We also found signs of interaction
between climate/hydrology and land use intensity, in particular in the
presence of point sources of P, leading to a bias towards underestimation of
P in hydrologically stable streams and overestimation of P in flashy streams.
Based on our findings, we suggest that the evaluation and use of more
accurate monitoring methods, such as automatized flow-proportional water
samplers and automatized bankside analyzers, should be prioritized whenever
logistically possible. However, it seems particularly relevant in currently
flashy systems and also in systems where climate change predictions suggest
an increase in stream flashiness
Impacts of climate warming on lake fish community structure and potential effects on ecosystem function
Fish play a key role in the trophic dynamics of lakes, not least in shallow systems. With climate warming, complex changes in fish community structure may be expected owing to the direct and indirect effects of temperature, and indirect effects of eutrophication, water-level changes and salinisation on fish metabolism, biotic interactions and geographical distribution. We review published and new data supporting the hypotheses that, with a warming climate, there will be changes in: fish community structure (e.g. higher or lower richness depending on local conditions); life history traits (e.g. smaller body size, shorter life span, earlier and less synchronised reproduction); feeding mode (i.e. increased omnivory and herbivory); behaviour (i.e. stronger association with littoral areas and a greater proportion of benthivores); and winter survival. All these changes imply higher predation on zooplankton and macroinvertebrates with increasing temperatures, suggesting that the changes in the fish communities partly resemble, and may intensify, the effects triggered by eutrophication. Modulating factors identified in cold and temperate systems, such as the presence of submerged plants and winter ice cover, seem to be weaker or non-existent in warm(ing) lakes. Consequently, in the future lower nutrient thresholds may be needed to obtain clear-water conditions and good ecological status in the future in currently cold or temperate lakes. Although examples are still scarce and more research is needed, we foresee biomanipulation to be a less successful restoration tool in warm(ing) lakes without a strong reduction of the nutrient load.
The history of seabird colonies and the North Water ecosystem: Contributions from palaeoecological and archaeological evidence
Brazil's new fish farming Decree threatens freshwater conservation in South America
Aquaculture has tremendous importance in providing food for a growing world population. Nevertheless, unsustainable aquaculture causes nutrient buildup and favors biological invasions in natural habitats, demanding strategies to regulate such activity and therefore minimize environmental risks. Contrary to these concerns, the Brazilian Government has recently issued a new Federal Decree (10576/2020) encouraging the farming of invasive non-native species and excluding the Ministry of Environment from the legal process of issuing fish farming permits in reservoirs. The Decree increases the risk of non-native species establishment in inland waters at a national level and their propagation into neighboring countries, such as Argentina, Bolivia, Paraguay, and Uruguay. These consequences will endanger preserved freshwater ecosystems in the continent, including their native biodiversity, which represents both a problem of national sovereignty and a threat to the fundamental human right for a healthy environment. For this reason, the Decree contradicts the Brazilian Federal Constitution and conflicts with international treaties regulating invasive species and promoting sustainable development. It calls for immediate legal action and is yet another unfortunate sign of the increasing gap between science and decision making that has plagued the country in recent years.Fil: Latini, Anderson Oliveira. Universidade Federal de Sao Joao Del-rei; BrasilFil: Mormul, R. P.. Universidade Estadual de Maringá. Departamento de Engenharia Química.; BrasilFil: Giacomini, H. C.. Universidade Estadual de Maringá. Departamento de Engenharia Química.; Brasil. Universidade Santa Cecília; BrasilFil: Di Dario, F.. Universidade Federal do Rio de Janeiro; BrasilFil: Vitule, J. R. S.. Universidade Federal do Paraná; BrasilFil: Reis, R. E.. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Tonella, L.. Universidade Estadual de Maringá. Departamento de Engenharia Química.; BrasilFil: Polaz, C. N. M.. Centro Nacional de Pesquisa E Conservação de Peixes Continentais; BrasilFil: Lucifora, Luis Omar. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lima, L. B.. Universidade Federal do Mato Grosso do Sul; BrasilFil: Teixeira-de-Mello, F.. Universidad de la República; UruguayFil: Lima Júnior, D. P.. Universidade Federal do Mato Grosso do Sul; BrasilFil: Magalhães, A.L.B.. No especifíca;Fil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Jimenez Segura, L. F.. Universidad de Antioquia; ColombiaFil: Azevedo Santos, V. M.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Carvalho, F. R.. Universidade Federal do Mato Grosso do Sul; BrasilFil: D'Anatro, A.. Universidad de la Republica; UruguayFil: Malabarba, L. R.. Universidade Federal do Rio Grande do Sul; BrasilFil: Mandelburger, D.. Ministerio del Ambiente y Desarrollo Sostenible; ParaguayFil: Orsi, M.L.. Universidade Estadual de Londrina; BrasilFil: González Bergonzoni, I.. Cenur Litoral Norte – Sede Paysandú; Uruguay. Universidad de la República; UruguayFil: Cunico, A.M.. Universidade Federal do Paraná; BrasilFil: Petrere Júnior, M.. Universidade Federal do Pará; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Scarabotti, Pablo Augusto. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Vidal, N.. Universidad de la República; Urugua