Bahan Bacaan Benthos Kaitannya Dengan Fisika Kimia Air

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   Acta Limnologica Brasiliensia  Influence of environmental factors on benthic macroinvertebrate communities of urban streams in Vereda habitats, Central Brazil Influência de variáveis ambientais na comunidade de macroinvertebrados bentônicos de córregos urbanos de Veredas, Brasil Central Renata de Moura Guimaraes Souto 1 , Kátia Gomes Facure 2 , Luis Alfredo Pavanin 3 and Giuliano Buzá Jacobucci 4 1 Programa de Pós-Graduação em Ecologia e Conservação de Recursos Naturais, Universidade Federal de Uberlândia – UFU, CEP 38408-100, Uberlândia, MG, Brazil e-mail: rebioguimaraes@yahoo.com.br 2 Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia – UFU, CEP 38408-100, Uberlândia, MG, Brazil e-mail: katiafacure@hotmail.com   3 Instituto de Química, Universidade Federal de Uberlândia – UFU, CEP 38408-100, Uberlândia, MG, Brazil e-mail: pavanin@ufu.br   4 Instituto de Biologia, Universidade Federal de Uberlândia – UFU, CEP 38408-100, Uberlândia, MG, Brazil e-mail: gbjacobucci@yahoo.com.br  Abstract:    Aim: Veredas and the aquatic and semi-aquatic communities play a key role in watershed protection in the Cerrado Biome. Information about the effects of physical and chemical variables and habitat integrity on benthic communities has been increased in recent years; however, there is no study evaluating the influence of urbanization on macroinvertebrates of Vereda streams. Tus, improving the knowledge of the relationship between abiotic properties and benthic fauna is very important for understanding the functioning of ecological processes and health of aquatic ecosystems. Tis study investigated the influence of physical and chemical variables on benthic macroinvertebrate communities along a gradient of anthropogenic disturbance in four Vereda streams in Uberlândia (MG), one in a preserved area and three in the urban area;  Methods: samplings were collected during the dry and rainy seasons;  Results: principal component analysis separated the stream in the preserved area from those in the urban area by having lower values of BOD, COD, sediment size, conductivity, detergents, pH, deposited solids and total dissolved solids. Pollution sensitive groups (e.g., Ephemeroptera and richoptera) were associated to the stream in the preserved area, and more tolerant groups (e.g., Chironomidae and Oligochaeta) had greater abundance in the streams of the urban area. Canonical Correspondence Analysis indicated that dissolved oxygen, conductivity, BOD, oil and grease, and turbidity explained 56% of the variance in the distribution and abundance of macroinvertebrates;  Conclusions: Benthic communities of Vereda streams in urban areas in the Cerrado Biome seem to be highly affected by human activities that increase water organic pollution and sedimentation. Keywords:  bioindicators, environmental quality, pollution, Cerrado. Resumo:   Objetivo: Veredas e comunidades aquáticas e semi-aquáticas desempenham importante papel na proteção das bacias hidrográficas no Bioma Cerrado. Informações sobre efeitos de variáveis físico-químicas e da integridade do habitat nas comunidades de macroinvertebrados bentônicos têm aumentado nos anos recentes, entretanto, não há estudos avaliando a influência da urbanização nas comunidades de macroinvertebrados em córregos de veredas. Assim, ampliar o conhecimento da relação entre as variáveis abióticas e fauna bentônica é muito importante para a compreensão do funcionamento dos processos ecológicos e da integridade dos ecossistemas aquáticos. Este estudo investigou a influência de variáveis físicas e químicas nas comunidades de macroinvertebrados bentônicos ao longo de um gradiente de distúrbios antrópicos em quatro córregos de Vereda em Uberlândia (MG); um em uma área preservada e três na área urbana;  Métodos: as amostras foram coletadas nas estações seca e chuvosa;  Resultados:  A análise de componentes principais separou o córrego da área preservada daqueles da área urbana por apresentar menores valores de DBO, DQO, tamanho do sedimento, condutividade, detergentes, pH, sólidos depositáveis e sólidos totais dissolvidos. Grupos sensíveis à poluição (e.g., Ephemeroptera , 2011, vol. 23, no. 3, p. 293-306 http://dx.doi.org/10.1590/S2179-975X2012005000008   Souto, RMG. et al.  Acta Limnologica Brasiliensia  1. Introduction Benthic macroinvertebrates inhabit river beds, lakes and reservoirs and are associated with various types of substrates such as mineral sediments, detritus, macrophytes and filamentous algae (Rosenberg and Resh, 1993). hey are essential elements in lentic and lotic trophic webs, participating in the energy flow and nutrient cycling (Whiles and Wallace, 1997). hey are also important food resources for fish (Wallace and Webster, 1996) and some insectivorous birds (Ward et al., 1995).Te distribution of aquatic organisms is the result of interactions among their ecological role, the physical conditions that characterize the habitat, and food availability (Merritt and Cummins, 1984). Tus, the community structure of benthic macroinvertebrates depends on a number of factors, namely water quality, type of substrate, particle size of sediment, water flow, sediment organic matter availability, oxygen concentration as well as environmental conditions surrounding the watercourse (Ward et al., 1995; Buss et al., 2004).Because they reflect environmental changes, benthic macroinvertebrates are often used as indicators of the effects of human activity on water system and provide information on habitat and water quality (Woodcock and Huryn, 2007). Te organic enrichment of water caused by both domestic and industrial effluents is a common anthropogenic impact on urban watercourses. Tis kind of pollution changes physical and chemical characteristics of lotic systems, thus affecting the assemblage of benthic macroinvertebrates (Hynes, 1970; Ward et al., 1995).Te Cerrado, the second largest Brazilian biome occupies 21% of the country and is considered a hotspot due to its impressive biodiversity and endemism and the accelerated rates of deforestation. Te Cerrado is cited in scientific literature as one of the biomes that have the highest species richness of the world and much of this richness has yet to be known (Oliveira-Filho and Medeiros, 2008), including freshwater invertebrates. About 80% of its natural range was converted to urban occupation or agricultural activities, involving, among many consequences, degradation of water sources. Te clearing of native vegetation reaches, in most cases, the forests adjacent to watercourses which, in this biome, occupy areas of good soil (Ribeiro et al., 2001). Tis vegetation is important to maintain the ecological equilibrium of aquatic environments, minimizing erosion and sediment deposition. Among the various physiognomies associated with Cerrado, the Veredas are very widespread in this biome, and they are highlighted because they are closely related to waterways. Te Veredas are wetlands, with hydromorphic soils that can be very rich in organic matter (Wantzen et al., 2006). Tey occur in small valleys with distinctive hydrophytic vegetation (Lima 1996), including tree-shrub species, dominated by the buriti palm (  Mauritia    vinifera   Mart.), and several grass species (Oliveira and Marquis, 2002).Veredas and the aquatic and semi-aquatic communities play a key role in watershed protection. Tey minimize erosion and provide food, living space, breeding places and escape routes to local fauna that depends directly or indirectly on the plants (Oliveira and Marquis, 2002).Information about the effects of physical and chemical variables and habitat integrity on benthic communities in Brazil has been increased in recent years (Callisto et al., 2001; Marques and Barbosa, 2001; Buss et al., 2002; Buss et al., 2004; Bispo et al., 2004; Bispo et al., 2006; Buckup et al., 2007; Couceiro et al., 2007; Hepp and Santos, 2009). However, there is no study evaluating the influence of urbanization on macroinvertebrates of Vereda streams in the Cerrado Biome.hus, improving the knowledge of the relationship between abiotic properties and benthic fauna is very important for understanding the e richoptera) foram associados ao córrego da área preservada e grupos mais tolerantes (Chironomidae e Oligochaeta) tiveram maior abundância nos córregos da área urbana.  A Análise de Correspondência Canônica indicou que oxigênio dissolvido, condutividade, DBO, óleos e graxas e turbidez explicaram 56% da variação na distribuição e abundância de macroinvertebrados;  Conclusões: comunidades bentônicas de córregos de Vereda em áreas urbanas no Bioma Cerrado parecem ser altamente afetadas pelas atividades humanas que aumentam a poluição orgânica da água e a sedimentação. Palavras-chave:  bioindicadores, qualidade ambiental, poluição, Cerrado. 294  Influence of environmental factors… (Köeppen, 1948). Uberlândia is located in a climate region with annual mean temperatures ranging from 19 to 27 °C and average rainfall around 1500 mm.year –1  (Silva and Assunção, 2004).Four streams (Cabeceira do Lageado, Buritizinho, Lobo and Bons Olhos) located in different regions of the urban area of Uberlândia (55° 08’ 18” S and 48° 16’ 37” W) were selected (Figure 1). Te streams have width varying from 1.5 to 2.5 m and depth ranging from 0.15 to 0.80 cm. All stream headwaters are situated in Vereda environments with predominantly muddy sandy substrate. Although they are located in permanent preservation areas (APPs), in urban areas in general and specifically in Uberlândia, degradation of Veredas is recurrently causing profound environmental disturbances (Schiavini and Araújo, 1989).For better representation of the streams three sampling sites were established in each stream, one near the headwaters (P1), another near the mouth (P3) and another intermediate between these (P2). Te headwaters of the Lageado stream (Stream 1) are located in an ecological reserve (Reserva do Clube de Caça e Pesca) about 10 km from Uberlândia city functioning of ecological processes and integrity of aquatic ecosystems. he data generated are particularly important for planning interventions to preserve or manage water systems, to ensure its biological integrity or, in other words, the system’s ability to maintain its natural biodiversity and essential ecological processes for their perfect functioning.In this context, this study aimed to characterize the distribution patterns and seasonal variation of benthic macroinvertebrate communities in streams from an urban area of Central Brazil, and to evaluate the influence of key environmental factors on these communities. 2. Material and Methods  2.1.Study site  Te study was performed in first order streams of the Uberabinha river basin, with about 2000 km 2 , in the riângulo Mineiro region, Minas Gerais state, Brazil. Te local climate is tropical and, according to the climate classification of Köppen is Aw type, megatermic, with summer rains and winter drought Figure 1. Uberabinha River Basin in the urban area of Uberlândia - MG and location of the studied streams (S1 Stream 1 – Cabeceira do Lageado; S2 Stream 2 – Buritizinho; S3 Stream 3 – Lobo and S4 Stream 4 – Bons Olhos) and sampling sites (P1; P2; P3). 2011, vol. 23, no. 3, p. 293-306 295   Souto, RMG. et al.  Acta Limnologica Brasiliensia  deposited solids and detergents were determined according to Macêdo (2003). Te suspended solids (Greenberg et al., 2005) and concentrations of manganese (Mn) and iron (Fe) (Pregnolato and Pregnolato, 1985) were also determined. One sediment sample was collected from each sampling site in rainy and dry periods to assess organic matter content (Pregnolato and Pregnolato, 1985) and particle size, totaling 12 samples per period.  2.4.Data analysis  Patterns of spatial and seasonal variation in benthic community composition and abundance and in environmental variables were described using Correspondence Analysis (CA) and Principal Component Analysis (PCA), respectively, performed with FIOPAC 1.5 (Shepherd, 2004). o assess the environmental variables explaining most of the variation on the distribution of macroinvertebrates, a Canonical Correspondence Analysis (CCA) was performed using the forward selection procedure in CANOCO 4.5 (erbraak and Smilauer, 2002). Multicollinearity was assessed by examining the Variance Inflation Factor (VIF). Only significant non-redundant variables were included in the final model. Abundances, turbidity, oil and grease, dissolved oxygen, sedimentable solids, suspended solids, Mn, BOD and organic matter had positively skewed distributions and were log-transformed. In addition, all environmental variables were standardized to the same scale (values between zero and one) before analyses. For PCA and CCA analysis, Chironomidae was separated from “Other Diptera”, Hydrophilidae from “Other Coleoptera”, and Hydropsychidae from “Other richoptera”. Tese families represent important groups both numerically and ecologically (more tolerant to pollution). he category “Other invertebrates” includes representatives of Nematoda, Isopoda, Lepidoptera and Hemiptera. 3. Results he values of physical and chemical water parameters are indicated in Figure 2. Te pH values were recorded in a slightly acidic range, with lower values in the dry season. For conductivity, lower values were found in Stream 1, higher values in Streams 2 and 3, and intermediate values in stream 4. In the dry season, the values of dissolved oxygen and turbidity were low in all streams, while in the rainy season higher values were recorded. Te values of BOD, COD and detergents were higher in Stream 2 and lower in other streams. A wide center. Te Buritizinho (Stream 2), Lobo (Stream 3) and Bons Olhos (Stream 4) streams are directly inserted into the urbanized area of Uberlândia and subject to various kinds of anthropogenic impacts mainly due to the loss of vegetation along the banks of streams and inflow of domestic sewage and garbage.  2.2.Sampling of benthic macroinvertebrates  Sampling of benthic macroinvertebrates was performed in rainy (March/2007) and dry (July/2007) seasons. At each sampling site of the streams, three substrate sub-samples were randomly collected, using a Surber collector of 900 cm 2  and of 0.25 mm mesh size. Te three sub-samples of each site were pooled and represented one sample, totaling 12 samples per sampling period.Te samples were packed in plastic bags, labeled, fixed in a 10% formalin solution, and transported to the laboratory for processing. Te collected material was washed on a mesh of 0.25 mm, and sorted in Petri dishes, using a stereomicroscope. Te benthic macroinvertebrates were identified to the family level - except the molluscs (Class), annelids (Subclass), nematodes (Phylum) and isopods (Order) - using specific identification keys (Wiggins, 1977; Merritt and Cummins, 1984; Righi, 2002).  2.3.Physical and chemical variables of water and sediment  In each sampling period, the sites were sampled three times (two weeks before macroinvertebrates sampling, simultaneously with macroinvertebrate sampling and two weeks after macroinvertebrate sampling) to evaluate physical and chemical variables of water and sediment. Water samples were collected in triplicate with amber bottles with 1.5 L capacity, at 20 cm water depth. Te samples were fixed and packed using techniques and methods described by the American Public Health  Association (APHA, 1995).Except for the measurement of water temperature, which was performed with a mercury thermometer, in situ, the other physical and chemical variables were analyzed in the laboratory. Te conductivity and pH were measured using a digital conductivity meter (Digimed DM-32) and a digital pHmeter (Digimed DMPH), respectively. Te turbidity was determined by nephelometric method (using a digital turbidimeter HD114) and Dissolved Oxygen by Winkler method. Biochemical oxygen demand (BOD5), chemical oxygen demand (COD), oil and grease concentration, total dissolved solids (DS), 296
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