1
|
Leal CG, Barlow J, Gardner TA, Hughes RM, Leitão RP, Nally RM, Kaufmann PR, Ferraz SFB, Zuanon J, de Paula FR, Ferreira J, Thomson JR, Lennox GD, Dary EP, Röpke CP, Pompeu PS. Is environmental legislation conserving tropical stream faunas? A large-scale assessment of local, riparian and catchment-scale influences on Amazonian fish. J Appl Ecol 2018; 55:1312-1326. [PMID: 32831394 PMCID: PMC7433846 DOI: 10.1111/1365-2664.13028] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Agricultural expansion and intensification are major threats to tropical biodiversity. In addition to the direct removal of native vegetation, agricultural expansion often elicits other human-induced disturbances, many of which are poorly addressed by existing environmental legislation and conservation programmes. This is particularly true for tropical freshwater systems, where there is considerable uncertainty about whether a legislative focus on protecting riparian vegetation is sufficient to conserve stream fauna.To assess the extent to which stream fish are being effectively conserved in agricultural landscapes, we examined the spatial distribution of assemblages in river basins to identify the relative importance of human impacts at instream, riparian and catchment scales, in shaping observed patterns. We used an extensive dataset on the ecological condition of 83 low-order streams distributed in three river basins in the eastern Brazilian Amazon.We collected and identified 24,420 individual fish from 134 species. Multiplicative diversity partitioning revealed high levels of compositional dissimilarity (DS) among stream sites (DS = 0.74 to 0.83) and river basins (DS = 0.82), due mainly to turnover (77.8% to 81.8%) rather than nestedness. The highly heterogeneous fish faunas in small Amazonian streams underscore the vital importance of enacting measures to protect forests on private lands outside of public protected areas.Instream habitat features explained more variability in fish assemblages (15%-19%) than riparian (2%-12%), catchment (4%-13%) or natural covariates (4%-11%). Although grouping species into functional guilds allowed us to explain up to 31% of their abundance (i.e. for nektonic herbivores), individual riparian - and catchment - scale predictor variables that are commonly a focus of environmental legislation explained very little of the observed variation (partial R2 values mostly <5%).Policy implications. Current rates of agricultural intensification and mechanization in tropical landscapes are unprecedented, yet the existing legislative frameworks focusing on protecting riparian vegetation seem insufficient to conserve stream environments and their fish assemblages. To safeguard the species-rich freshwater biota of small Amazonian streams, conservation actions must shift towards managing whole basins and drainage networks, as well as agricultural practices in already-cleared land.
Collapse
Affiliation(s)
- Cecília G. Leal
- Museu Paraense Emílio Goeldi, Belém, PA, Brazil
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
- Fish Ecology Laboratory, Federal University of Lavras, Lavras, MG, Brazil
| | - Jos Barlow
- Museu Paraense Emílio Goeldi, Belém, PA, Brazil
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | | | - Robert M. Hughes
- Amnis Opes Institute and Department of Fisheries & Wildlife, Oregon State University, Corvallis, OR, USA
| | - Rafael P. Leitão
- National Institute for Amazonia Research, Manaus, AM, Brazil
- Department of General Biology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ralph Mac Nally
- Institute for Applied Ecology, The University of Canberra, Bruce, ACT, Australia
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Vic., Australia
| | - Philip R. Kaufmann
- Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR, USA
| | - Silvio F. B. Ferraz
- Forest Hydrology Laboratory (LHF), Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, SP, Brazil
| | - Jansen Zuanon
- National Institute for Amazonia Research, Manaus, AM, Brazil
| | - Felipe R. de Paula
- Forest Hydrology Laboratory (LHF), Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, SP, Brazil
| | | | - James R. Thomson
- Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, Heidelberg, Vic., Australia
| | - Gareth D. Lennox
- Museu Paraense Emílio Goeldi, Belém, PA, Brazil
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Eurizângela P. Dary
- Institute of Natural, Human and Social Sciences, Federal University of Mato Grosso, Sinop, MT, Brazil
| | - Cristhiana P. Röpke
- Faculty of Agrarian Sciences and Institute of Biology, Federal University of Amazonas, Manaus, AM, Brazil
| | - Paulo S. Pompeu
- Fish Ecology Laboratory, Federal University of Lavras, Lavras, MG, Brazil
| |
Collapse
|
2
|
Dary EP, Ferreira E, Zuanon J, Röpke CP. Diet and trophic structure of the fish assemblage in the mid-course of the Teles Pires River, Tapajós River basin, Brazil. Neotrop ichthyol 2017. [DOI: 10.1590/1982-0224-20160173] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT This study was carried out in a section of the middle course of the Teles Pires River, a clear water river that drains ancient and highly eroded geological formations, and where five hydropower plants are planned or in construction. In this study we tested the hypothesis that local fish fauna is mainly sustained by autochthonous food resources, with modest changes in the trophic structure of fish assemblages along the hydrometric cycle. Sampling was performed every three months between July 2008 and May 2009 at seven sites distributed along a 50-km section of the river. Piscivores was the most representative group in terms of biomass, abundance and species richness, followed by herbivores, insectivores and omnivores. The trophic structure did not change significantly during the hydrometric cycle, only omnivores showed significant temporal variation in abundance. The main food resources consumed by the ichthyofauna were of autochthonous origin, mainly immature aquatic insects and fish. Eight of 34 species showed temporal variations of the food resources consumed. Our results corroborate the hypothesis that the fish fauna of large, clear water rivers can be sustained by autochthonous resources. This contributes to understanding some determinants of fish production in large Neotropical rivers.
Collapse
Affiliation(s)
| | | | | | - Cristhiana P. Röpke
- Instituto Nacional de Pesquisas da Amazônia, Brazil; Universidade Federal do Amazonas, Brazil
| |
Collapse
|