Danielle Sequeira Garcez

Ichthyofauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, Northeastern Brazil

Humid highland forest enclaves are remnants of Atlantic Forest found in tablelands within the Caatinga biome (Northeastern Brazil), which emerged during interglacial periods in the Pleistocene. These ecosystems have a highly diverse and endemic fish fauna. Most earlier surveys have focused on the tableland of Borborema (Pernambuco and Paraiba States). In this study we surveyed the fish fauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, based on samples collected in the rainy season (March and April) between 2009 and 2014. The 45 sampling points covered rivers, streams and reservoirs in five river basins belonging to three ecoregions. The species were listed according to drainage divide, and endemism was determined for each ecoregion and for the Caatinga. Our area was more species-rich (n=59) than Borborema (n=27). The samples included five introduced species and 29 species endemic to the Caatinga (49.1% of the sampled species). The distribution of Parotocinclus haroldoi was expanded to the Mid-Northeastern Caatinga ecoregion (Timonha river basin, Ceara State). Our study intends to make a significant contribution to current knowledge of the ichthyofauna in humid highland forest enclaves of semiarid Northeastern Brazil, identified as a priority in the conservation of the biodiversity in the Caatinga.

Ichthyofauna of two reservoirs in the middle Acaraú river basin, Ceará, Northeastern Brazil

Few studies have been published on the taxonomy, biology and ecology of the fish fauna of the rivers and reservoirs from the Brazilian Caatinga. Considering the importance of fish surveys as subsidies for future studies and fishing resources management, the purpose of the present study was to assess the fish assemblage of the two largest reservoirs in the middle Acarau river basin, the Paulo Sarasate and the Edson Queiroz reservoirs, state of Ceara, Northeastern Brazil. Eight nycthemeral samplings were performed with gillnets (mesh size ranging from 3 to 12 cm between opposite knots) during rainy and dry season between 2010 and 2012. We captured 1,626 specimens belonging to three orders, nine families and 17 species, six of which are endemic to the Caatinga. Approximately 30% of the species observed were non-native and had been introduced for stocking purposes.

On the relation amongst limnological factors and fish abundance in reservoirs at semiarid region

Aim: To evaluate possible nycthemeral and seasonal temporal patterns in fish assemblage associated with limnological aspects and biotic factors in two reservoirs in semarid Northeastern Brazil. Methods: Fish were sampled with gillnets in nycthemeral cycles throughout the dry and rainy season in two reservoirs (Paulo Sarasate/PS and Edson Queiroz/EQ). The stomach contents of the predator species were surveyed. The limnological variables were submitted to principal components analysis, while their relation to fish abundance was determined by canonical correspondence analysis. Temporal patterns in relative fish species abundance were detected with nMDS. Results: Temperature and dissolved oxygen levels segregated the reservoirs physico-chemically. Turbidity and chlorophyll-a levels differed between seasons, and the relative abundance of species differed between the reservoirs. Predators were more abundant in PS, while detritivores were more abundant in EQ. Triportheus signatus and Plagioscion squamosissimus were the most abundant species in both reservoirs. In general, predator abundance was positively associated with high temperature and dissolved oxygen (PS>EQ) and negatively associated with turbidity. The activity patterns of P. squamosissimus could not be explained by fluctuations in environmental variables. Non-predators tended to cluster around the vectors chlorophyll-a, pH and turbidity. Predators had a more diversified diet in PS in accordance with food availability, while predators in EQ ate only fish and shrimp. Nycthemeral patterns varied for the same species depending on the reservoir. Generally, in PS predators were more active during daylight hours while non-predators were more active after dark. However, in EQ predators and non-predators displayed similar nycthemeral activity patterns. Regardless of the reservoir, predators were more abundant in the rainy season. No seasonal trend was observed for non-predators. Conclusions: Limnological differences between PS and EQ influenced temporal species abundance patterns. The species distribution was determined by predation conditions and physiological attributes.

Fish diversity in tidepools: assembling effects of environmental heterogeneity

Tidepools are considered ecosystems of high interchangeable fish biota. However, natural and anthropogenic actions that alter negatively marine ecosystems functioning (e.g., algal exploitation) are causing homogenization of fish biodiversity. Here, we describe the functional and taxonomic assembling of fishes in beach rocks of northeastern Brazil. Traits of fish species were retrieved from Fishbase and beta diversity was assessed by the dispersion of abundance, presence-absence and functional diversity in the multivariate space. We explained spatial-temporal variation in: alpha diversity, taxonomic and functional community composition; as well as temporal variation in functional, beta and gamma diversities. We found an annual stability in fish diversity and composition, and that fish biota was assembled mainly per tidepools’ depths. Substrate heterogeneity was correlated to depth, highlighting the role of local features as filters to organize the fish fauna vertically in tidepools, especially a cultivation of algae that influences the local assembling. We also highlight the uniqueness status of beach rocks in the Brazilian tropical region.

CARACTERIZAÇÃO PRODUTIVA DE UM PROJETO DE ASSENTAMENTO RURAL NO SEMIÁRIDO NORDESTINO (RIO GRANDE DO NORTE, BRASIL)

The rural settlements are agricultural production units created in order to reordering the use of land for the benefit of rural landless or with little land. However, it should be noted if them adequately fulfill its function after the first few years of installation. The objective of this study was to characterize aspects of the agricultural production of the Maisa Settlement Project, located in the Rio Grande do Norte State, Brazil. Interviews with community leaders from the ten rural villages that make up the settlement were made in August 2013. It was noted that land distribution did not occur equally between rural villages and dwellers; that the perception of community leaders is, in general, less than willing in government document, established by the agency responsible for agricultural development in Brazil (INCRA). It was identified that 1.7% of the area for cultivation is currently being used; and that crops planted are beans, melon, watermelon, corn, barbados cherry, papaya, pumpkin and grass. It was observed that a larger area is planted in the communal area (125 ha) than in cultivated in the Individual Lots (93.4 ha). However, the agricultural production in these two compartments shows a negative correlation, 4,861 and 6,070 tons, respectively. In 90% of rural villages the main source of income is wage labor on private farms. This study revealed that the Maisa Settlement is not fulfilling its social function, and that the productive potential is mainly related to the availability of financial resources to capture groundwater for irrigation.