Brazilian Estuaries Research Articles

Differences in the structure of copepod assemblages in four tropical estuaries: Importance of pollution and the estuary hydrodynamics

We examined the relationship between pollution and structure of copepod assemblages in estuaries, using sampling standardization of salinity range to reduce the effects of “Estuarine Quality Paradox”. Copepod assemblages were analyzed in four Southeast Brazilian estuaries with different water quality levels and different hydrodynamic characteristics. The pollution negatively impacted the descriptors of the assemblage structure. The distribution of structure of copepod assemblages also showed a main separation trend between the most polluted estuaries and those less polluted. Temperature was the main factor affecting the assemblage structuring in the four estuaries. This factor acted in synergism with the effects of pollution impact and physical characteristics of the estuaries on the structure of copepod assemblages, supporting the potential vulnerability of coastal environments due to nutrient enrichment associated with climate change. Our study demonstrated the importance of sampling standardization of the salinity range in estuaries for reliable analysis of pollution effects on biota.

Exploring ecosystem functioning in two Brazilian estuaries integrating fish diversity, species traits and food webs

Exploring ecosystem functioning in two Brazilian estuaries integrating fish diversity, species traits and food webs

Mugil curema as a PAH bioavailability monitor for Atlantic west sub-tropical estuaries

This work aimed to evaluate the use of Mugil curema as a biomonitor for polycyclic aromatic hydrocarbon (PAH) bioavailability. Fish biliary metabolites from low-contaminated (Cananéia) and contaminated (Santos) Brazilian estuaries were analysed using a high-performance liquid chromatography apparatus coupled to fluorescence detectors connected in a series. In the Cananéia and Santos estuaries, total metabolite levels ranged from 0.85 to 34.4μgg−1 of bile and from 4.06 to 528μgg−1 of bile, respectively. Metabolite levels were not influenced by feeding status or sexual hormones (p<0.05), thus suggesting that M. curema is a good biomonitor for PAH bioavailability. In estuarine regions, it is possible to sample both the male and female genders of this species in any reproductive period.

Comparações entre medições em tempo real da pCO2 aquática com estimativas indiretas em dois estuários tropicais contrastantes: o estuário eutrofizado da Baía de Guanabara (RJ) e o estuário oligotrófico do rio São Francisco (AL)

Carbon dioxide (CO2) fluxes from aquatic systems are generally derived from the gradient in the partial pressure of CO2 (pCO2) between air and surface waters. In this study, we compare real-time measurements of water pCO2 using an equilibrator and non-dispersive infrared gas detector, with calculations based on pH and total alkalinity (TA) in two contrasting Brazilian estuaries: Guanabara Bay (Rio de Janeiro) and the Sao Francisco River Estuary (Alagoas). In Guanabara Bay, the measured and calculated values showed an excellent agreement (R2 = 0.95, p < 0.0001), without significant statistical differences between the two methods. In the Sao Francisco River Estuary, where the entire gradient from freshwaters to seawater could be sampled, important overestimates were found for the calculated pCO2. The overestimation was on average 71%, and reached up to 737%. This large bias in pCO2 calculation was verified at low pH and TA concentrations in freshwaters (pH < 7.5; TA < 700 µmol kg-1) possibly due to the contribution of organic alkalinity, lowering the buffer capacity of the carbonate system. As such, direct measurements of pCO2 should be considered as a priority for CO2 studies conducted in estuarine systems, particularly tropical systems where physical and biological processes are prone to significant spatial and temporal variability.

Are natural reservoirs important for cholera surveillance? The case of an outbreak in a Brazilian estuary.

Paranaguá Bay is one of the largest estuarine systems on the Southern Brazilian coast. The only recorded cholera outbreak in this region since the early 20th century occurred in 1999 and resulted in 467 cases and at least three reported deaths in a population of approx. 150000 people. This short communication reports historical, unpublished data related to that outbreak. Water, zooplankton and bivalve samples were collected and evaluated using direct fluorescence assay to determine whether Vibrio cholerae serogroups O1 and O139 were present in the estuarine system at that time. Most of the water (83%) and zooplankton samples (75%) were positive for V.cholerae O1, while V.cholerae O139 was not detected. Shellfish (Mytella sp.) were also positive for V.cholerae O1. These results indicate that the estuary, including biological vectors such as copepods and bivalves, comprise an important reservoir of V.cholerae O1 and a probable waterborne pathway for the disease, in addition to contamination with untreated sewage. Despite most of the cholera cases that occurred in Brazil during the 7th pandemic were located in the northern areas of the country, a significant outbreak in Paranaguá, an estuary in the south coast, resulted in at least three deaths in 1999. We report here the detection of Vibrio cholerae O1 in water, zooplankton and bivalve samples during the outbreak, using direct fluorescence assay as an alternative method for the traditional plate culture employed at the time by the Brazilian Sanitary Agency. Results demonstrate that aquatic natural reservoirs comprise a potential route of transmission of cholera, in addition to untreated sewage and routine monitoring is recommended.

Spatial patterns of distribution and the influence of seasonal and abiotic factors on demersal ichthyofauna in an estuarine tropical bay.

This study focused on the influence of local-scale environmental factors on key metrics of fish community structure and function at Guanabara Bay, an estuarine system that differs from all other south-western Atlantic estuaries due to the influence of an annual low-intensity upwelling event during late spring and summer, between November and March, when a warm rainy climate prevails. The spatial patterns of the bottom temperature and salinity were more heterogeneous during the rainy season than the dry season, being linked to total precipitation and seasonal oceanographic events. The study identified 130 species and 45 families, placing Guanabara Bay as one of the most species-rich tropical estuarine ecosystems, far exceeding 22 other Brazilian estuaries. These results, in addition to characteristics such as a relatively well-preserved mangrove forest, high productivity and favourable conditions for the growth and reproduction of estuarine species, indicate that Guanabara Bay plays a central role in supporting large populations of fishes, including commercially important species.

Do different degrees of human activity affect the diet of Brazilian silverside Atherinella brasiliensis?

The aim of the present study was to test whether different degrees of human activity affect the diet of the Brazilian silverside Atherinella brasiliensis in two tropical estuaries. Fish were collected along the salinity gradient of two Brazilian estuaries, the heavily impacted Paraiba Estuary and the less impacted Mamanguape Estuary, in the dry and wet seasons. The findings confirm that A. brasiliensis has generalist feeding habits and is able to change its diet under different environmental conditions. The results indicate clear spatial (i.e. along the estuarine gradient) changes in diet composition in both estuaries, but diet was also influenced by the degree of anthropogenic disturbance. During the wet season in the nutrient enriched Paraiba Estuary, when human activity was higher, the diet of A. brasiliensis was poorer and dominated by few dietary items, reflecting the potential impoverishment of prey items in this heavily disturbed system. The specimens collected in the most affected estuary also had a greater frequency of micro-plastics and parasites in their stomachs, reflecting the greater degree of human disturbance in the estuary. The present findings suggest that the diet of A. brasiliensis could be a useful indicator of changes in the ecological quality of these and other tropical estuaries of the western Atlantic Ocean.

Genetic structuring among silverside fish (Atherinella brasiliensis) populations from different Brazilian regions

Estuaries are dynamic environments, key for the survival of innumerous ecologically or economically important fish species. Among these species are Neotropical silversides (Atherinella brasiliensis), which are resident and abundant in Brazilian estuaries and used as a complementary source of income and food for local communities. To better understand silverside populations in Brazil, we evaluated the genetic diversity, structure and demography of fish sampled at six estuaries from the northeastern to the southern coast, using Random Amplified Polymorphic DNA and mitochondrial DNA (D-loop) markers. High haplotype diversities (h ranging from 0.75 to 0.99) were found in all populations except Carapebus, located in Southeast Brazil (h = 0.54). A total of 69 mtDNA haplotypes were found, with Itaparica (Northeast Brazil) and Carapebus presenting only exclusive haplotypes, while some were shared among populations in the South. Strong regional structure was observed, with very high differentiation between Itaparica and Carapebus, as well as among these two populations and the ones from the Southern region (Paranaguá, Conceição, Camacho and Patos). Among southern areas, low/moderate structure was detected. Most populations showed unimodal mismatch distributions indicating recent demographic expansion, while Carapebus presented a multimodal distribution characteristic of a stable or bottlenecked population. Times since possible population expansion were highest in Itaparica (32,500 ya) and Carapebus (29,540 ya), while in the Southern region longest time was observed at Conceição (25,540 ya) and shortest at Patos (9720 ya). In a general manner, haplotype diversities were directly related to times since population expansions; again, Carapebus was the exception, displaying long time since expansion but low diversity, possibly due to a recent bottleneck caused by the isolation and human impacts this lagoon is subject to. Isolation by Distance was significant for Itaparica and Carapebus, and considering the extremely high differentiation of these populations, we suggest that they could be undergoing speciation. To adequately manage and maintain the genetic variability of silversides in Brazilian estuaries, we propose three distinct management units for this species: 1) Itaparica; 2) Carapebus; and 3) Southern Brazil.

Observation of an Estuarine Turbidity Maximum in the Highly Impacted Capibaribe Estuary, Brazil

Estuarine turbidity maxima (ETM) are features present in some estuaries where the concentration of suspended particulate matter (SPM) is higher than elsewhere along the fresh-marine water transition in the estuarine domain (POSTMA, 1967; SCHUBEL, 1968; GEYER, 1993; DYER, 1995). The presence of ETM has important ecological implications: since they occur at places where there is an accumulation of organic matter: bacterioplancton and zooplankton dynamics in estuaries is affected by ETM behavior (CRUMP; BAROSS, 1996; MORGAN et al., 1997). ETM are also important in the pollutants dynamics of an estuary, mainly for those that occur adsorbed to fine clayey sediments (BRUNK et al., 1996). ETM are formed and maintained as the result of complex interactions between river discharge, tidal dynamics and gravitational circulation (DYER, 1988). The concentration of SPM in the ETM varies over time on tidal, sinodical and seasonal time scales (GRABEMANN et al., 1997). ETM have been studied in many estuaries abroad (ALLEN et al., 1980; GELFENBAUM, 1983; UNCLES et al., 1994; WOLANSKI et al., 1995). In some estuaries they are of an ephemeral nature (KISTNER; PETTIGREW, 2001), while in other cases they do not occur at all (SCHETTINI; TOLDO JUNIOR, 2006; SCHETTINI et al., 2006). The physics underlying the formation of the ETM has been studied using both analytical and numerical models (GEYER, 1993; JAY; MUSIAK, 1994; BURCHARD; BAUMERT, 1998; YU et al., 2014) in which the effect of gravitational circulation and tidal pumping is of primary importance, with a high degree of interaction between the flow and the bed. Most ETM have been reported in meso or macro-tidal estuaries. As regards the Brazilian coast, it is not expected to find ETM in the Southeastern and Southern Regions basically because the tidal regime is microtidal. Some papers have reported ETM processes in Paranagua Bay (PR) (e.g., RIBEIRO et al., 2011), although the higher turbidity zone in that estuary is linked rather to re-suspension due to tidal currents (MANTOVANELLI et al., 2004) than to the occurrence of a true ETM. Other studies on SPM in southern Brazilian estuaries have not reported the presence of ETM (SCHETTINI; TOLDO JUNIOR, 2006; D´AQUINO et al., 2010). On the other hand, meso and macro tides occur on the shores of the Northeastern and Northern Regions, where there would be a greater likelihood of observing ETM. Nevertheless, there are not many studies of the fine sediment dynamics of this area, and the few that are available do not report the presence of ETM. The fine sediment dynamics of the Caravelas estuary, Bahia has been assessed (SCHETTINI; MIRANDA, 2010; SCHETTINI et al., 2013), despite the fact that this estuary presents a very small freshwater inflow, and the major source of sediments is the inner shelf. Such conditions are unfavorable to the formation of ETM. The eastern shores of Para seem to present favorable conditions for the formation of ETM, and a single survey carried out in the Caete estuary has shown a feature in the longitudinal distribution of SPM which fits in with what is expected of an ETM (ASP et al., 2012), even though it has not yet been assessed.A series of surveys has been carried out in the Capibaribe estuary since 2012 to investigate its circulation, fine sediment transport, deposition patterns and recent environmental evolution. The main appeal of and reason for these assessments was the fact that the Capibaribe estuary is a relatively small system (~ 10 km

Endocrine disruption in Sphoeroides testudineus tissues and sediments highlights contamination in a northeastern Brazilian estuary.

In recent decades, considerable attention has been devoted to endocrine disruptor chemicals (EDC) and studies on fish feminization have increased throughout the years as a key signal for aquatic environmental contamination. The input of domestic sewage into water reservoirs is common in South American countries, especially in cities that experienced rapid population growths and unplanned urbanization. This study aimed at characterizing morphofunctional parameters of the tropical fish Sphoeroides testudineus and investigating the potential occurrence and effects of endocrine disruptors in the Pacoti River (Ceará, Brazil), often considered a reference site. After collection from the field, fish were measure/weighted and desiccated for gender identification (males, females, and undifferentiated), gonadal histology, and vitellogenin expression. From the biometric analysis, undifferentiated fish showed lower weight and length than female and male fish, although no differences in the condition index were observed. The gonadal weight of undifferentiated fish was significantly lower than those of females and males. Although this pattern was observed, gonadosomatic index (GSI) showed a different pattern, with differences being observed just between males and the other two groups (females and undifferentiated). Vitellogenin (VTG) expression was detected in many mature male and undifferentiated fish, indicating endocrine disruption. In addition, several EDCs (estrone, 17α-estradiol, 17β-estradiol, 17α-ethinylestradiol, diethylstilbestrol, and estriol) were identified and quantified in sediments from the sampling site. These results were unexpected and indicative that the Pacoti River is impaired by estrogenic contamination.

Natural and human controls of water quality of an Amazon estuary (Caeté-PA, Brazil)

Estuarine waters are usually eutrophic due to nutrients input derived from natural and anthropogenic sources. In the Caeté Estuary, nutrients and thermotolerant coliforms input is intensified by the absence of a public sanitation system and by mangrove outwelling. This input is more accentuated in the upper sector of the estuary where 90% of the local population is concentrated and a high incidence of commercial activities (public markets, ice factories and boat repairing among others) is located. As a consequence, eutrophic waters with high concentrations of thermotolerant coliforms (up to 1100 MPN/100 ml) were observed during the dry season when dilution and/or advection are less effective. Eutrophication, though less pronounced, also occurred in the other sectors (middle and lower), but these results seem to indicate that this could be a natural condition of an Amazon region which is naturally enriched with a high amount of nutrients. On the other hand, nutrient concentration values in the upper sector are similar to those found in other highly populated and industrialized Brazilian estuaries. Taking into account that the population increases by about 20% per decade in the region, this growth may lead to a significant increase in human pressure and impacts on the area, mainly during periods when the estuary is more susceptible to retaining nutrients (e.g., during the dry season). In order to improve water quality, the DPSIR framework was used as a guide for proposing potential measures to be implemented in the Caeté Estuary based on (i) urban planning to control sewage discharges, (ii) construction of water treatment infrastructures to reduce untreated effluents inputs and (iii) water use regulations as a function of the current water quality.

Identifying multiple-use conflicts prior to marine spatial planning: A case study of A multi-legislative estuary in Brazil

Marine spatial planning (MSP) is essential to solve spatial multiple-use problems, but first it is necessary to identify and map all existing uses, regulations and conflicts. Use conflicts related to the multi-legislative governance, neglect of fishermen's interests, and intensifying industrial growth due to economic development were identified for in a multiple-use Brazilian estuary. Overlaps between areas that are presently used for fishing and areas that are subject to regulations prohibiting this activity were analyzed. Information on regulations establishing no-fishing zones, the most important fishing sites and fishing records were gathered and superimposed using a GIS dataset. Main fishing zones were located within prohibited fishing areas. Regulations limiting fishing activity govern navigation routes and pipeline safety zone, whereas environmental law restrictions were less important. Due to economic and industrial development, oil and gas distribution and harbor construction projects are increasing, aggravating use conflicts and jeopardizing fishing activity. Legislation fragments usable fishing areas forcing fishers to operate within prohibited zones. Neglect of fishermen's interests, and their exclusion on the decision-making process led to a legislative scenario that reduce fishing legal zone to few areas, which in most cases fisherman are not even aware were they are, beingthe main reasons for fisher's failure to comply with the current regulations, increasing the number of infractions and the marginalization of fishermen. Future studies on multiple-use coastal areas subject to multiple jurisdictions should focus on all uses, not only environmental, to better understand spatial conflicts and to establish a realistic MSP embracing fisheries management, environmental conservation and economic development.

Benthic estuarine communities in Brazil: moving forward to long term studies to assess climate change impacts

Abstract Estuaries are unique coastal ecosystems that sustain and provide essential ecological services for mankind. Estuarine ecosystems include a variety of habitats with their own sediment-fauna dynamics, all of them globally undergoing alteration or threatened by human activities. Mangrove forests, saltmarshes, tidal flats and other confined estuarine systems are under increasing stress due to human activities leading to habitat and species loss. Combined changes in estuarine hydromorphology and in climate pose severe threats to estuarine ecosystems on a global scale. The ReBentos network is the first integrated attempt in Brazil to monitor estuarine changes in the long term to detect and assess the effects of global warming. This paper is an initial effort of ReBentos to review current knowledge on benthic estuarine ecology in Brazil. We herein present and synthesize all published work on Brazilian estuaries that has focused on the description of benthic communities and related ecological processes. We then use current data on Brazilian estuaries and present recommendations for future studies to address climate change effects, suggesting trends for possible future research and stressing the need for long-term datasets and international partnerships.

Foraminifera, Thecamoebians, and Bacterial Activity in Polluted Intertropical and Subtropical Brazilian Estuarine Systems

ABSTRACT Laut, L.L.M.; Martins, V.; da Silva, F.S.; Crapez, M.A.C.; Fontana, L.F.; Carvalhal-Gomes, S.B.V., and Souza, R.C.C.L., 2016. Foraminifera, thecamoebians, and bacterial activity in polluted intertropical and subtropical Brazilian estuarine systems. This study aims to identify relationships between total organic matter (TOM), bacterial carbon (BC), and metabolic activity in the thecamoebian and foraminifera community of five estuarine regions on the Brazilian coast. Sediment samples were collected from the subtidal zone of five Brazilian estuaries: Potengi, Mataripe Sound, Paraiba do Sul, Surui, and Itacorubi. A total of 21 thecamoebian species, 29 species of agglutinated foraminifera, and 55 species of calcareous foraminifera were identified. In these estuaries the anaerobic process was dominant. In the Potengi Estuary, located in the NE coast of Brazil, the assemblages showed a decrease in diversity and richness as well as an increase in bacterial carbon concentrations. In the other estuaries th...

Evaluation of impacted Brazilian estuaries using the native oyster Crassostrea rhizophorae: Branchial carbonic anhydrase as a biomarker

In this study, we investigated the use of branchial carbonic anhydrase activity in a sessile filter feeding species, the oyster Crassostrea rhizophorae, as a biomarker. The oysters were collected in three human impacted Brazilian estuaries, following a crescent latitudinal gradient: in Pernambuco state (Itamaracá), in Espírito Santo state (Piraquê), and in Paraná state (Paranaguá), in August/2003 (Winter in the southern hemisphere) and February/2004 (Summer). Three sites were chosen in each estuary for oyster sampling: Reference (R), Contaminated 1 (C1, close to industrial/harbor contamination), and Contaminated 2 (C2, near to sewage discharges). Comparing to values in oysters sampled in reference sites, there was apparent inhibition in carbonic anhydrase activity (CAA) in gills of oysters from C1 of Itamaracá and from C2 of Piraquê, both cases in Summer. On the other hand, increased CAA was noted in C2 oysters of Itamaracá in winter, and of Paranaguá, in both seasons. Branchial CAA in C. rhizophorae was thus very responsive to coastal contamination. Data are consistent with its usefulness as a supporting biomarker for inexpensive and rapid analysis in the assessment of estuaries using a sessile osmoconformer species, but preferably allied to other biomarkers and with knowledge on the suite of contaminants present.

Evaluation of catch-and-release angling practices for the fat snook Centropomus parallelus in a Brazilian estuary

Recreational fisheries are developing for many iconic marine and estuarine fish species and are generating important social and economic returns in Brazil. Fat snook is the primary target species in southeastern Brazil and it supports a vibrant fisheries sector, including recreational fishing tournaments. To evaluate the impacts of recreational angling practices, we examined external hooking injuries, secondary physiological stress responses (i.e., blood glucose and lactate concentrations; N = 24), reflex impairment (N = 39), and overnight survival (N = 39) of fat snook angled with and without air exposure. We also examined physiological stress and reflex impairment of fat snook captured in a fishing tournament (N = 43) immediately post weigh-in and 1 h post weigh-in. Values were compared to baseline reflexes (N = 10) and physiology (N = 8) collected from minimally stressed fat snook. Fish captured by anglers infrequently had hooking injury but all angling and tournament treatments resulted in significantly elevated blood glucose and lactate, indicating a considerable physiological response to angling. Angling with air exposure and tournament weigh-in (in a dry container) resulted in the highest blood lactate values. The body flex reflex was occasionally impaired after angling or tournament practices, but this was consistent with baseline reflex actions, and the body flex reflex was therefore not a valuable indicator of fisheries stress or mortality in fat snook. Although angling and tournament practices caused a marked physiological stress response, low mortality of snook indicated that the species is resilient to brief bouts of angling at moderate water temperatures. However, high lactate values associated with air exposure suggest that handling practices be refined, particularly during tournament weigh-in. We recommend that anglers reduce air exposure intervals when handling snook prior to release and that recreational tournaments adopt wet weigh-in procedures to maximize the utility of catch-and-release in this fishery.

Impact of harbour, industry and sewage on the phosphorus geochemistry of a subtropical estuary in Brazil

The distribution of different forms of phosphorus in surface sediment from 17 sites were investigated by SEDEX method. The sites were divided into three sectors: Santos Channel (SC – influenced by harbour, fertilizers plants and phosphogypsum mountains), São Vicente Channel (SVC– domestic waste) and Santos Bay (SB – sewage outfall). The average percentage of each P fraction of the surface sediments in this region followed the sequence P–Fe (38%)>Porg (27%)>Pexch (13%)>Detrital – P (12%)>Auth – P (10%). Ptotal varied from 3.57 to 74.11μmolg−1 in both seasons. In SVC, Pexch ranged from 13% to 27% and Porg varied from 12% to 56%. These high percentages of Pexch/Ptotal (greater than 20%) may be related to low oxygen resulting from oxygen consumed by intensive organic matter decomposition as well as the salty water that leads to cation and anion flocculation. Also, the possibility of an influence related to the industrial source of Pexch is not ruled out. No significant seasonal differences were found among sites, except for sewage outfall, with changing in the grain size and hence, the P geochemistry. During the summer in the sewage outfall station, Porg represented 37% of Ptotal, which decreased to 13% in the winter. These results suggest that high percentages of organic phosphorus cannot be attributed only to autochthonous and allochthonous organic matter, but also to detergents and/or domestic waste. In contrast, spatial differences among sectors were observed, with the highest values of each fraction associated with sites near industrial and domestic waste activities.

Poaceae communities in the savannas of the Amazon Estuary in Brazil

We sought to identify the major environmental factors that affect the diversity and distribution of Poaceae in the savannas of the Amazon Estuary. The study was conducted across seven areas of savanna in the Amazon Estuary, within which 160 subplots of 1 m2 each were established within four 10 × 100 m plots. Soil samples were collected at a depth of 0-20 cm. A total of 24 Poaceae species were recorded. Only two were common to all of the areas studied (Axonopus aureus P. Beauv. and Anthaenantia lanata (Kunth) Benth). The edaphic factors that most influenced the Poaceae in the savannas studied were organic matter, coarse sand, and silt contents. Conversely, rainfall had no effect. The floristic and structural characteristics of the savannas studied suggest that Poaceae communities exhibit low diversity and a peculiar distribution pattern in which a group of species predominate in a given stretch, creating a homogeneous physiognomy. Our findings suggest that the structure of these communities is related to a gradient of soil texture, the percentage of Axonopus and Trachypogon coverage increasing and decreasing, respectively, along that gradient. These data can contribute to the understanding of plant-soil interactions in this environment, promoting strategies for conservation, management, and revegetation.

Marine debris in a World Heritage Listed Brazilian estuary

Using monthly otter-trawl deployments, spatial and temporal variability among the relative densities of marine debris were assessed in the Paranaguá estuarine complex; a subtropical World Heritage Listed area in southern Brazil. During 432 deployments over 12months, 291 marine debris items were identified; of which most (92%) were plastic, and more specifically shopping bags, food packages, candy wrappers and cups typically >21mm long. The most contaminated sectors were those closest to Paranaguá city and the adjacent port, and had up to 23.37±3.22 pieces ha−1. Less urbanized sectors had between 12.84±1.49 and 9.32±1.10 pieces ha−1. Contamination did not vary between dry or wet seasons, but rather was probably affected by consistent urban disposal and localized hydrological processes. Marine debris might be minimized by using more environment friendly materials, however a concrete solution requires adequately integrating local government and civil society.

Priority areas for the conservation of the fish fauna of the Amazon Estuary in Brazil: A multicriteria approach

The definition of priority areas for the conservation of fish faunas is still relatively incipient in comparison with efforts for the protection of terrestrial systems, despite the fact that fishes are the group of organisms most affected by anthropogenic impacts. Given the lack of adequate management in the most important sectors of the Amazon Estuary, the objectives of the present study were to identify priority areas for conservation, based on the analysis of ecological and economic criteria, and indices referencing the fish fauna, integrated in a GIS environment. This was the first application of a methodological approach of this kind to the Amazon Estuary. Fish specimens were collected in the main channel and tidal creeks of the southern Amazon Estuary – Guajará and Marajó Bays and the mouth of the Guamá River and associated islands – between 2004 and 2011, during both the dry (July to December) and rainy seasons (January to June), using gillnets and trawls. A total of 14 ecological and fishery criteria were grouped in five indices – environmental quality and diversity, habitat use, fishery index, and relative abundance (CPUE). Maps were produced, based on different scenarios for the conservation of the fish fauna of the study area. Medium to high conservation priorities were defined by all the indices throughout the study area. The scenarios indicated that the northern portion of Marajó Bay and all sectors during the dry season present medium to very high priorities for conservation.