Phylogeography of Hypomasticus copelandii Reveals Distinct Genetic Lineages along Atlantic Coastal Drainages of Eastern Brazil (Teleostei, Anostomidae)

Hypomasticus copelandii is a Neotropical freshwater fish widely distributed across coastal drainages of southeastern Brazil, a highly impacted region of South America. The interspecific phylogenetic relationships within the genus and the taxonomic status of the species remain uncertain. Using two mitochondrial and one nuclear locus, we performed a phylogenetic, species delimitation, and time-calibrated analyses to test the hypothesis that H. copelandii is a species complex currently delimited by different Atlantic coastal systems. Results indicate that H. copelandii presents two well-delimited genetic lineages: one in the northern drainages of the Jucuruçu, Mucuri and Doce rivers, and the other in the southern region represented by the Paraíba do Sul River Basin. The time-calibrated phylogeny indicated a split between the two genetic lineages at around 2.8 million years ago (Ma), which might be related to headwater capture events during the Plio-Pleistocene. The discovery of a distinct genetic lineage for H. copelandii suggests distinct management plans for the northern and southern drainages. Such hidden diversity within the H. copelandii provides useful information for taxonomy and conservation across a severely impacted region of Brazil.

Biological aspects of Hypostomus affinis (Siluriformes: Loricariidae) in Brazilian coastal rivers

Aim Determine the length-weight relationship (LWR), the period of reproduction, and evaluate the variation of the condition factor (K) of Hypostomus affinis from two coastal drainages in southeastern Brazil, assessing the influence of the rainfall on these biological aspects. Methods fish were sampled quarterly between April 2008 and April 2010 in tributaries of the Doce River basin (DRB) and the Paraíba do Sul River basin (PSRB). Specimens were caught using gillnets. LWR parameters were assessed by location and sex through a t-test. We used the frequency of mature specimens (FM) to evaluate the breeding period. Both FM and K values were assessed by a sinusoidal equation. Results A total of 492 specimens was captured, of which 128 were from the Doce River basin (DRB) and 364 from the Paraíba do Sul River basin (PSRB). In both areas, specimens showed a negative allometric growth type. We collected mature specimens along the studied period in both drainages, with the highest frequency observed at the beginning of the rainy season. We found a positive correlation between the rate of matures and the local rainfall variation. The condition factor (K) was lower for specimens from DRB and did not show a cyclic trend. On the other hand, we observed a cyclic chance of the K values for the individual from the PSRB, peaking in the transitional dry-rainy period. However, it was not possible to correlate it to the rainfall variation. Conclusions LWR parameters of H. affinis were consistent with data already available in the literature. The rainfall may influence the FM but not the K values. In this case, biological characteristics such as reproduction and (or) feeding may be jointly driving a discrete variation of K values. The reduction in K values in the rainy periods suggests a remarkable energetic cost for the reproductive process. In short, our results help us to understand the life cycle of a fish species within a highly modified environment, especially by dams.

Environmental magnetism evidence for longshore drift distribution of Fe-bearing phases: An example from the Brazilian southeastern coastal region

ABSTRACT The accumulation of heavy minerals along a part of the southeastern Brazilian coast (northern coast of Rio de Janeiro State, Brazil) provides insight into sedimentary provenance and transport by longshore drift. In particular, recent work has focused on heavy minerals as tracers to determine sedimentary sources and transport pathways, indicating a mineral distribution according to the northward and southward coastal transport cells. There is also evidence of heavy-mineral transport by the Paraíba do Sul River. However, research has not been done in this area on the opaque fraction (iron oxides and oxyhydroxides), which are good tracers for provenance and distribution processes. Here we intend to: 1) characterize the spatial variation of the magnetic properties of heavy-mineral contents throughout a coastal area of the Itabapoana and Paraíba do Sul River mouths (state of Rio de Janeiro), 2) evaluate the contribution of coastal dynamics on the mineral distribution along this coastal area, 3) provide contributions on the provenance of iron-bearing minerals. Results indicate that a bimodal pattern was observed for the magnetic remanence of magnetite and hematite near the Paraíba do Sul River. For the northernmost section, goethite exhibits a gradual increase in concentration towards the central part of the study area. Additionally, higher heavy-mineral content is observed at the northern coastal section, which may be related to coastal morphology, which is exposed to high-energy beach processes. It is possible to verify three sampling groups in accordance with their magnetic properties: 1) the “southernmost” and 2) the “northernmost” groups, suggesting a mineral provenance related to the Paraíba do Sul and Itabapoana rivers, respectively, as possible major sources, and 3) another at the intermediate section of the area, possibly linked to the erosion of the Barreiras Formation bluffs. Results also show a correspondence between the variability of magnetic parameters and the main directions of the coastal transport cells.

Effect of rainfall seasonality and land use on the water quality of the paraíba do sul river

Monitoring water quality is important for the suitable management of water resources. Therefore, this study aims to assess the main water quality parameters and the National Sanitation Foundation-Water Quality Index (WQINSF) of four locations on the Paraíba do Sul River basin, in the state of Rio de Janeiro, influenced by different land use and land cover, and in the dry and rainy seasons. The following quality parameters were evaluated: total phosphorus (TP), nitrate (NO3-), dissolved oxygen (DO), potential of hydrogen (pH), turbidity (Turb), thermotolerant coliforms (Col), total dissolved solids (TDS), biochemical oxygen demand (BOD), water temperature (Twater) and air temperature (Tair). Statistical differences (p < 0.05) were observed between the dry and rainy seasons for the parameters: TP, Col, Turb, TDS, Twater, Tair, NO3-, DO, and WQINSF. The concentration of rainfall was effective in water quality parameters behavior. WQINSF was lower in the rainy season and possibly the runoff was the major cause of water quality degradation. Land use and land cover influenced the concentration of DO and Col and, consequently, WQINSF. Despite statistical differences, in most cases, the Paraíba do Sul River basin lies in medium water quality index according to the classification of the National Water and Sanitation Agency (ANA).

Effects of land use change on discharge of the Paraíba do Sul river

The Paraíba do Sul river basin is located in the southeast region of Brazil and across São Paulo, Rio de Janeiro and Minas Gerais states. In addition to the urban and rural population in the basin, Paraíba do Sul River supplies about twelve million people in the Metropolitan Region of Rio de Janeiro, the third-largest metropolitan region in South America. Land-use in the basin is predominantly dairy farming, where inadequate soil management has affected the quality and quantity of water in the basin. In this work, a distributed hydrological model was performed to assess different surface coverage scenarios considering increments of forest cover along to the basin watercourses. The scenarios were compared with the current condition of the basin in terms of annual mean streamflow, annual maximum daily streamflow, and frequency of occurrence of very high and very low flow extremes. The simulations indicate a reduction in the annual mean streamflow rate due to the increase of the cover forest; reduction of annual maximum daily streamflow due to the increase in forest cover. Extreme frequency analysis indicates that increasing forest cover promotes a decrease in very high flow events and an increase in very low flow events during the rainy months of the basin (October to March), however, in the dry months (especially in August) the occurrence of very high flow events increases while very low flow events decrease. These results indicate that although on average and during the rainy season forest cover negatively affects surface water availability in the driest months, when water resources are scarcer, increased forest cover is beneficial for water availability in the basin.