Spatial and Temporal Hydrochemical Variation of a Third Order River Network in a Quasi Pristine Coastal Watershed, at Southern Bahia, Brazil

ABSTRACT Rio da Serra watershed presents well preserved fragments of rain forest at the headwaters and small farms at middle and final stretches. These features allowed the study of fluvial hydrochemistry, under quasi pristine conditions. Sampling stations were established in order to represent the basin, and visited during dry, intermediate and wet periods. Obtained results are: temperature (22.1 – 28.6 °C); electric conductivity (34 – 52 µS/cm); dissolved oxygen (35 – 110%); pH (3.8 – 7.7); total suspended solids (1.1 – 20 mg/L); chlorophyll (1.0 – 9.2 µg/L); total N (74 – 580 µmol/L); particulate N (60 – 550 µmol/L); N-NO3 (0.1 – 9.3 µmol/L); dissolved organic N (4 -70 µmol/L); total phosphorous (5.3 – 47 µmol/L); particulate P (4.4 – 59 µmol/L); P-PO4 (0.1 – 0.7 µmol/L); dissolved organic P (0.01 – 2.0 µmol/L); silicate (30 -90 µmol/L); fecal coliforms (80 – 700 CFU/100mL). In seasonal terms dissolved oxygen, electric conductivity, nitrate and silicate concentrations were higher during the dry, whereas TSS was higher during the wet period. Seasonal differences of dissolved oxygen, temperature, pH and nitrate were also detected near wetlands areas. Along the basin results showed a distinction between headwaters and other sections, revealing a control of fluvial hydrochemistry by the preserved area, mostly for the dissolved organic N and P species and phosphate

Benthic Estuarine Assemblages of the Southeastern Brazil Marine Ecoregion (SBME)

We assess the current knowledge of the benthic assemblages in the Southeastern Brazil Marine Ecoregion (SBME), which extends for approximately 1200 km of coastline and includes seven major estuarine systems from Guanabara Bay in Rio de Janeiro to Babitonga Bay (or Sao Francisco do Sul) in Santa Catarina. The high ecosystem diversity of SBME putatively accounts for the high levels of endemism of the regional marine invertebrate fauna. However, until more taxonomical and biogeographical evidence is available, the SBME should be treated as a working biogeographical hypothesis rather than a cohesive unit identified by endemic fauna. As a consequence of urban, agricultural, and industrial development, the coastal areas from the SBME have been the most altered in the country over the last 500 years. Some of the largest cities and busiest harbors of the country are in or near the regional estuarine areas. The rapid environmental changes over the last several decades do not allow for the assessment if current similarities and dissimilarities in the benthic assemblages express pristine conditions or if they are already the result of major human interventions, especially in the case of the Guanabara, Sepetiba, and Santos estuaries.Univ Fed Parana, Ctr Estudos Mar, Pontal Do Sul, Parana, BrazilUniv Fed Sao Paulo, Inst Mar, Santos, SP, BrazilUniv Catolica Norte, Millennium Nucleus Ecol & Sustainable Management, Fac Ciencias Mar, Dept Biol Marina, Coquimbo, ChileUniv Estadual Paulista, Inst Biociencias, Campus Litoral Paulista, Sao Vicente, SP, BrazilUniv Fed Fluminense, Dept Biol Marinha, Campus Valonguinho, Niteroi, RJ, BrazilUniv Estadual Paulista, Inst Biociencias, Campus Litoral Paulista, Sao Vicente, SP, Brazi