Estudos da APA – Biblioteca Digital Itupararanga

Menu

An applied ecological approach for the assessment of anthropogenic disturbances in urban wetlands and the contributor river

Este trabalho é somente para uso privado de atividades de pesquisa e ensino. Não é autorizada sua reprodução para quaisquer fins lucrativos. Esta reserva de direitos abrange a totalidade dos dados do documento bem como seu conteúdo. Na utilização ou citação de partes do documento é obrigatório mencionar o nome da pessoa autora do trabalho.

Uma abordagem ecológica aplicada para a avaliação de perturbações antropogénicas em zonas húmidas urbanas e no rio contribuinte

ABSTRACT

An applied ecological approach was used to assess the anthropogenic disturbances on the aquatic systems of the Sorocaba river and its wetlands in the Sorocaba-SP municipality (Southeastern Brazil). Two samplings of water, sediment, macroinvertebrates, and macrophytes were performed in 2017, during the rainy season (February) and dry season (June). Traditional limnological methods were applied to the biological material (macrophytes and macroinvertebrates) and limnological variables. In 2017, domestic wastewater and diffuse pollution were the main anthropogenic impacts on the aquatic ecosystems of the Sorocaba municipality. The used approach allowed the verification of the human disturbances on aquatic systems, sediment, biological communities, and landscape. We found that biochemical oxygen demand, thermotolerant coliforms, total phosphorus, dissolved oxygen, and turbidity are above reference concentrations from the Brazilian guideline CONAMA Resolution 357/05. Four macroinvertebrates orders (Diptera, Oligochaeta, Hirudinea, and Gastropoda) and three macrophytes species (Eichhornia crassipes, Salvinia auriculata and Pistia stratiotes) allowed inferring that Sorocaba river and associated wetlands suffer water quality loss due to organic pollution. The major land use classes were anthropogenic agricultural and non-agricultural (75.42%) disturbances, contributing to limnological alterations and low quality of riparian vegetation. Urban wetlands were similar (e.g. sediment properties, limnological variables, bioindicators) and differed from the contributor river, a situation probably related to the wetlands bimodal pulse. Considering the hydric network of tropical countries in the same geographic region, the similar dynamics of the water bodies, and the context of urbanization, the approach can be applied to assess the human disturbances in the region.

RESUMO

Uma abordagem ecológica aplicada foi utilizada para avaliar as perturbações antrópicas nos sistemas aquáticos do rio Sorocaba e suas áreas úmidas no município de Sorocaba-SP (sudeste do Brasil). Duas amostragens de água, sedimento, macroinvertebrados e macrófitas foram realizadas em 2017, durante a estação chuvosa (fevereiro) e a estação seca (junho). Métodos limnológicos tradicionais foram aplicados ao material biológico (macrófitas e macroinvertebrados) e às variáveis ​​limnológicas. Em 2017, águas residuais domésticas e poluição difusa foram os principais impactos antrópicos nos ecossistemas aquáticos do município de Sorocaba. A abordagem utilizada permitiu a verificação das perturbações humanas nos sistemas aquáticos, sedimentos, comunidades biológicas e paisagem. Descobrimos que a demanda bioquímica de oxigênio, coliformes termotolerantes, fósforo total, oxigênio dissolvido e turbidez estão acima das concentrações de referência da Resolução CONAMA 357/05. Quatro ordens de macroinvertebrados (Diptera, Oligochaeta, Hirudinea e Gastropoda) e três espécies de macrófitas ( Eichhornia crassipes, Salvinia auriculata e Pistia stratiotes ) permitiram inferir que o rio Sorocaba e as áreas úmidas associadas sofrem perda de qualidade da água devido à poluição orgânica. As principais classes de uso da terra foram distúrbios antropogênicos agrícolas e não agrícolas (75,42%), contribuindo para alterações limnológicas e baixa qualidade da vegetação ripária. As áreas úmidas urbanas foram semelhantes (por exemplo, propriedades dos sedimentos, variáveis ​​limnológicas, bioindicadores) e diferiram do rio contribuinte, uma situação provavelmente relacionada ao pulso bimodal das áreas úmidas. Considerando a rede hídrica de países tropicais na mesma região geográfica, a dinâmica semelhante dos corpos d’água e o contexto de urbanização, a abordagem pode ser aplicada para avaliar as perturbações humanas na região.

Introduction

Wetlands are important aquatic ecosystems that have been losing area during the last decades due to the landscape cover changes, and the economic development, and natural area conversion (Sannigrahi et al., 2018, Quintela et al., 2019). Among the main threats to the wetland ecosystems, the following elements stand out: (i) water pollution and (ii) biological invasion by exotic species, and (iii) human activity development, and the (iv) socioeconomic development context (Yang et al., 2018, Garcia et al., 2017).

This increasing pressure on water resources, including wetlands, may be worse in urban areas once in those spaces the superficial water quality is affected by point sources (e.g. waste pipe) or non-point sources (e.g. nutrient discharges during heavy rainfall) (Delkash et al., 2018). The city area increase causes physical degradation to the aquatic ecosystems, due to the rupture in the wetland connectivity (Guida et al., 2016), the substance insertions (e.g. sediments, heavy metals), and structural changings (e.g. plumbing, rectification).

Furthermore, those environments contribute to the water quality loss due to the nutrient discharging, which is one of the greatest urbanization consequences (Delkash et al., 2018). When in excess, the nutrients (i.e. phosphorus and nitrogen) reduce the water quality, creating conditions for the eutrophication, affecting the human and biodiversity needs (Laterra et al., 2018).

Wetlands play an important role, those ecosystems are responsible for sustaining the ecological and socio-cultural processes, providing essential ecosystem services (e.g. Silva et al., 2019) to cities and collaborate positively with human health and urban quality of life (Hettiarachchi et al., 2014; Lavoie et al., 2016). Besides the many ecosystem services provided for all society, the wetlands still face reductions in its area and increasing human appropriations on the ecosystem’s services (Sannigrahi et al., 2018).

An urban wetland should be characterized by its functions and processes (Haase et al., 2014). The appropriate decisions for the wetlands management have a dependence relation with the (i) regional environmental characteristics, (ii) resources changes, (iii) regional differences in the changes processes, and (iv) the changes drivers (Omernik and Griffith, 2014).

The management must be based on ecological precepts, in addition to considering the local characteristics and stimulating the development process without compromising the wetlands ecosystem integrity. There is a need for assessment methods that allow an integrated evaluation of these systems, characterizing human interference and indicating the main interference drivers to management strategies formulation.

Another important characteristic to be observed is the regional influence on wetlands, a factor that generates changes in the system dynamics. For example, the precipitation regimes have a strong influence on South America wetlands, and this situation implies in terrestrial and aquatic oscillation due to the flood pulse (Fushita and Santos, 2017, Bozelli et al., 2018), resulting in changes of the river connection and water volume.

The constant debates in the academy and the public environmental policy formulation have not been enough to reverse the current wetlands degradation and water quality loss. Some implemented development policies are affecting wetlands ecosystems (Veléz et al., 2018).

In the Brazilian scenario, there is a lack of a robust normative dispositive to provide effective protection and reinforce the institutional compromises for the wetland protection (e.g. Sousa et al., 2011; Junk et al., 2014; Maltchik et al., 2018; Grasel et al. 2018). In this sense, there is an urgent need to verify ways to evaluate the human impact on Brazilian wetlands ecosystems, which can contribute to an efficient management.

The Sorocaba municipality (SP) is inserted in a region where the land has been exploited for more than four centuries, but the last thirty years have been marked by the urbanization process increase, natural areas reduction (Silva, 2010; Bortoleto et al., 2016) and the Sorocaba river wetlands degradation.

The present work aims to assess the relationship between the Sorocaba river and its wetlands, using an ecological applied approach, based on land use, and physical-chemical, and biological analysis, pointing out the human interference and implications for environmental management. We hypothesized that: urban wetlands that have a low order river as a contributor experience human disturbance, however, the wetlands undergo a strong effect from the flood pulse, which implies wetlands similarities during the seasonal periods and differences between the contributor river and wetlands.

Section snippets

Study area

The Sorocaba Municipality (47 ° 34 ‘12,000′ ‘W / 23 ° 21′ 3,600 ” S and 47 ° 18 ‘10,800′ ‘W / 23 ° 35′ 20,058 ” S) is inserted in the São Paulo southwest region (Figure 1) and belongs to the Hydric Resources Management Unit (UGRH) Sorocaba-Médio Tietê. The climate according to Köppen’s classification is Cwa type, characterized by a dry season from April to October and a rainy season from November to March; the average annual rainfall is around 1311.2 mm (Centro de Pesquisas Meteorológicas e

Results

The physical and chemical variables for the sampling stations and associated wetlands are provided in the supplementary material (Tables S2 and S3). The rainy season showed higher mean temperature values (23.28°C) than the dry season (19.85°C), but temperature varied with sampling hour and the depth of the aquatic environments.

According to the thermotolerant coliforms values, the Sorocaba river stations (i.e. R1, R2, R6, and R7) present concentrations above the CONAMA Resolution 357/05 (1,000

Discussion

The River Continuum Concept (Vannote et al., 1980) is based on the premise that a lotic environment shows a continuum gradient from spring to river mouth of physic variables (e.g. flood, temperature, width) that deeply influence the biological communities and ecological process. Sorocaba river is a large river, the discharge favors reductions in temperature, and electrical conductivity values, and pH, and total dissolved solids, and total suspended solids, and dissolved oxygen concentrations,

Conclusions

The ecological approach that was applied was based on land use, and limnological analysis, and biotic communities, and riparian vegetation enabled the verification of the main human interferences in Sorocaba Municipality (diffuse pollution and domestic sewage) and it can be employed in other wetland ecosystems. The organic matter input was reflected on electrical conductivity, and biochemical oxygen demand, and dissolved oxygen concentrations and the organism, indicating the water quality loss, 

CRediT authorship contribution statement

Fabio Leandro da Silva: Conceptualization, Methodology, Formal analysis, Writing – original draft. Marta Severino Stefani: Data curation. WelberSenteio Smith: Supervision, Writing – review & editing, Visualization. Daniele Cristina Schiavone: Data curation. Marcela Bianchessi da Cunha-Santino: Writing – review & editing, Visualization. Irineu Bianchini Jr: Writing – review & editing, Visualization.

Declaration of Competing Interests

The authors declare that they have no conflict of interest

Acknowledgment

Financial support was provided by the National Council of Technological and Scientific Development(Process number: 830728/1999-6 and 158927/2018-4). The authors are grateful for the support provided by the Universidade Federal de São Carlos (Hydrobiology Department in special). We also thank Catia Cristina Teodoro, Marcos Marcilio, and André Puga, for the support during the sampling in the limnological stations. We are grateful to the anonymous reviewers, that provided valuable comments to

References (88)

There are more references available in the full text version of this article.

Cited by (13)