RESUMO
Human land-use change is a major threat to natural ecosystems worldwide. Nonetheless, the effects of human land-uses on the structure of plant and animal assemblages and their functional characteristics need to be better understood. Furthermore, the pathways by which human land uses affect ecosystem functions, such as biomass production, still need to be clarified. We compiled a unique dataset of fish, arthropod and macrophyte assemblages from 61 stream ecosystems in two Neotropical biomes: Amazonian rainforest and Uruguayan grasslands. We then tested how the cover of agriculture, pasture, urbanization and afforestation affected the taxonomic richness and functional diversity of those three species assemblages, and the consequences of these effects for animal biomass production. Single trait categories and functional diversity were evaluated, combining recruitment and life-history, resource and habitat-use, and body size. The effects of intensive human land-uses on taxonomic and functional diversities were as strong as other drivers known to affect biodiversity, such as local climate and environmental factors. In both biomes, the taxonomic richness and functional diversity of animal and macrophyte assemblages decreased with increasing cover of agriculture, pasture, and urbanization. Human land-uses were associated with functional homogenization of both animal and macrophyte assemblages. Human land-uses reduced animal biomass through direct and indirect pathways mediated by declines in taxonomic and functional diversities. Our findings indicate that converting natural ecosystems to supply human demands results in species loss and trait homogenization across multiple biotic assemblages, ultimately reducing animal biomass production in streams.
Assuntos
Artrópodes , Ecossistema , Humanos , Animais , Biomassa , Rios/química , BiodiversidadeRESUMO
Many studies have shown that biodiversity regulates multiple ecological functions that are needed to maintain the productivity of a variety of ecosystem types. What is unknown is how human activities may alter the 'multifunctionality' of ecosystems through both direct impacts on ecosystems and indirect effects mediated by the loss of multifaceted biodiversity. Using an extensive database of 72 lakes spanning four large Neotropical wetlands in Brazil, we demonstrate that species richness and functional diversity across multiple larger (fish and macrophytes) and smaller (microcrustaceans, rotifers, protists and phytoplankton) groups of aquatic organisms are positively associated with ecosystem multifunctionality. Whereas the positive association between smaller organisms and multifunctionality broke down with increasing human pressure, this positive relationship was maintained for larger organisms despite the increase in human pressure. Human pressure impacted multifunctionality both directly and indirectly through reducing species richness and functional diversity of multiple organismal groups. These findings provide further empirical evidence about the importance of aquatic biodiversity for maintaining wetland multifunctionality. Despite the key role of biodiversity, human pressure reduces the diversity of multiple groups of aquatic organisms, eroding their positive impacts on a suite of ecological functions that sustain wetlands.
Assuntos
Ecossistema , Áreas Alagadas , Animais , Organismos Aquáticos , Biodiversidade , Brasil , HumanosRESUMO
Under increasing nutrient loading, shallow lakes may shift from a state of clear water dominated by submerged macrophytes to a turbid state dominated by phytoplankton or a shaded state dominated by floating macrophytes. How such regime shifts mediate the relationship between taxonomic and functional diversities (FD) and lake multifunctionality is poorly understood. We employed a detailed database describing a shallow lake over a 12-year period during which the lake has displayed all the three states (clear, turbid and shaded) to investigate how species richness, FD of fish and zooplankton, ecosystem multifunctionality and five individual ecosystem functions (nitrogen and phosphorus concentrations, standing fish biomass, algae production and light availability) differ among states. We also evaluated how the relationship between biodiversity (species richness and FD) and multifunctionality is affected by regime shifts. We showed that species richness and the FD of fish and zooplankton were highest during the clear state. The clear state also maintained the highest values of multifunctionality as well as standing fish biomass production, algae biomass and light availability, whereas the turbid and shaded states had higher nutrient concentrations. Functional diversity was the best predictor of multifunctionality. The relationship between FD and multifunctionality was strongly positive during the clear state, but such relationship became flatter after the shift to the turbid or shaded state. Our findings illustrate that focusing on functional traits may provide a more mechanistic understanding of how regime shifts affect biodiversity and the consequences for ecosystem functioning. Regime shifts towards a turbid or shaded state negatively affect the taxonomic diversity and FD of fish and zooplankton, which in turn impairs the multifunctionality of shallow lakes.
Assuntos
Ecossistema , Lagos , Animais , Biomassa , Peixes , FitoplânctonRESUMO
Insect abundance and diversity are declining worldwide. Although recent research found freshwater insect populations to be increasing in some regions, there is a critical lack of data from tropical and subtropical regions. Here, we examine a 20-year monitoring dataset of freshwater insects from a subtropical floodplain comprising a diverse suite of rivers, shallow lakes, channels and backwaters. We found a pervasive decline in abundance of all major insect orders (Odonata, Ephemeroptera, Trichoptera, Megaloptera, Coleoptera, Hemiptera and Diptera) and families, regardless of their functional role or body size. Similarly, Chironomidae species richness decreased over the same time period. The main drivers of this pervasive insect decline were increased concurrent invasions of non-native insectivorous fish, water transparency and changes to water stoichiometry (i.e. N : P ratios) over time. All these drivers represent human impacts caused by reservoir construction. This work sheds light on the importance of long-term studies for a deeper understanding of human-induced impacts on aquatic insects. We highlight that extended anthropogenic impact monitoring and mitigation actions are pivotal in maintaining freshwater ecosystem integrity.
Assuntos
Ecossistema , Água , Animais , Biodiversidade , Água Doce , Humanos , Insetos , RiosRESUMO
Biodiversity decline has been the focus of discussions in the last decade, especially on the amphibian species decline. After a scientometric analysis using international databases, we found that the number of peer-reviewed articles considering education practices related to the theme increased along with the number of ecological researches. However, the increase in ecological researches is much higher than the increase in publications of education practices. Studies suggest that conservation attitudes are important and that education practices are an important tool for improving human perceptions on this subject. In this sense, increase the publication of projects and programs results related to local education practices in international journals could help the dissemination of efficient methods for conservation, as well as facilitating access to information internationally, since species decline, especially for amphibians, is a global concern. Then, we suggest that educational practices, at least when related to conservation, should follow a more standardized protocol, and be published in international journals, as the efficiency of such practices should be evaluated and methods once published could help other nations to improve their ecological literacy.
Assuntos
Anfíbios , Bibliometria , Revisão da Pesquisa por Pares , Animais , Bases de Dados Bibliográficas , Ecologia/estatística & dados numéricos , Extinção Biológica , Humanos , Revisão da Pesquisa por Pares/tendências , Publicações Periódicas como AssuntoRESUMO
ABSTRACT Biodiversity decline has been the focus of discussions in the last decade, especially on the amphibian species decline. After a scientometric analysis using international databases, we found that the number of peer-reviewed articles considering education practices related to the theme increased along with the number of ecological researches. However, the increase in ecological researches is much higher than the increase in publications of education practices. Studies suggest that conservation attitudes are important and that education practices are an important tool for improving human perceptions on this subject. In this sense, increase the publication of projects and programs results related to local education practices in international journals could help the dissemination of efficient methods for conservation, as well as facilitating access to information internationally, since species decline, especially for amphibians, is a global concern. Then, we suggest that educational practices, at least when related to conservation, should follow a more standardized protocol, and be published in international journals, as the efficiency of such practices should be evaluated and methods once published could help other nations to improve their ecological literacy.
Assuntos
Humanos , Animais , Bibliometria , Revisão da Pesquisa por Pares/tendências , Anfíbios , Publicações Periódicas como Assunto , Bases de Dados Bibliográficas , Ecologia/estatística & dados numéricos , Extinção BiológicaRESUMO
The number of citations that papers receive has become significant in measuring researchers' scientific productivity, and such measurements are important when one seeks career opportunities and research funding. Skewed citation practices can thus have profound effects on academic careers. We investigated (i) how frequently authors misinterpret original information and (ii) how frequently authors inappropriately cite reviews instead of the articles upon which the reviews are based. To reach this aim, we carried a survey of ecology journals indexed in the Web of Science and assessed the appropriateness of citations of review papers. Reviews were significantly more often cited than regular articles. In addition, 22% of citations were inaccurate, and another 15% unfairly gave credit to the review authors for other scientists' ideas. These practices should be stopped, mainly through more open discussion among mentors, researchers and students.