Luis Esteban Krause Lanés

Species-area relationship and environmental predictors of fish communities in coastal freshwater wetlands of southern Brazil

In the Neotropics where fragmentation is common, environmental factors structuring fish communities are poorly known. In this study two hypotheses were tested in 13 coastal wetlands of southern Brazil: 1) physical features (such as wetland area, habitat diversity, water depth and temperature, and water and sediment chemistry) are important determinants of richness, density and composition of fish assemblages; and 2) species richness and composition of fish assemblages differ between wetlands with different hydroperiods (i.e. permanent versus intermittent). A total of 1,597 individuals distributed among 20 species were collected. Richness was positively associated with wetland area and water depth and it was negatively associated with water conductivity. The species-area power function explained 27.3% of the variation in richness. Fish richness was similar between permanent and intermittent wetlands. The density was negatively associated with water depth and temperature, and it was positively correlated with water nitrate concentration. The first three axes from the CCA accounted for 55.5% of total variation in fish composition. The most important variables related to fish composition were percentage of sediment organic matter, phosphorus concentration, habitat diversity and water depth. Composition of fish species changed among permanent and intermittent wetlands. Understanding the environmental factors that shape and maintain the biodiversity in these ecosystems is essential to develop conservation and management programs of wetlands in this region, where more than 90% of wetland systems have already been lost due to anthropogenic activities.

Abundance variations and life history traits of two sympatric species of Neotropical annual fish (Cyprinodontiformes: Rivulidae) in temporary ponds of southern Brazil

We investigated abundance variations and life history traits (body size, sex ratio, length–weight relationships and condition factor) of two species of annual fish (Austrolebias minuano Costa and Cheffe and Cynopoecilus fulgens Costa) in temporary ponds of southern Brazil. Six samples were taken from small temporary ponds during three annual seasons over 2 years (2008–2009). A total of 104 individuals of A. minuano and 433 individuals of C. fulgens were collected. The abundance of both species tended to decrease from autumn to spring in the 2 years. The overall sex ratio of A. minuano and C. fulgens were 1.0 male to 1.8 females and 1 male to 1.04 females, respectively. Juveniles of both species occurred only in autumn over the two years and no adult was observed during this season. While the length–weight relationship of A. minuano indicated hyperallometric growth, the relationship of C. fulgens indicated values close to isometric growth.

Threatened fishes of the world: Austrolebias nigrofasciatus Costa and Cheffe 2001 (Cyprinodontiformes: Rivulidae)

Common names: Annual fish, killifish. Conservation status: “Endangered” (Fontana et al. 2003, MMA 2004). Identification: 21–26 anal-fin rays in males and 18–23 in females, 19–22 caudal-fin rays, 27–29 vertebrae. Illustration by Felipe Ribas. Coloration: Males: body’s sides metallic blue, with 6–12 dark brown to black bars. Females: body’s sides light yellowish brown, with vertical rows of elongate gray spots, sometimes forming gray bars (Costa and Cheffe 2001; Costa 2006). Distribution: Endemic to river drainages associated with the margin of São Gonçalo channel, Patos-Mirim lagoon system, Rio Grande do Sul, southern Brazil. Abundance: Relatively abundant in its restricted area of occurrence, however there is not estimation on the size of population. Habitat and ecology: Inhabits seasonal wetlands that are formed during the rainy seasons in southern Brazil and it is registered syntopic occurrence in two other species of annual fish: Cynopoecilus melanotaenia and Austrolebias wolterstorffi. Reproduction: Sexual maturity reached about a month after the hatching and presents average fertility of around 30 eggs per week (Volcan 2009). Threats: The drainage and the landfill of areas of floodplain for urban construction in restricted area of distribution of the species and the cultivation of rice in adjacent areas to the São Gonçalo channel are the main threats. Conservation action: It was theoretically protected in its type-locality, in the Pontal da Barra swamp, whose area was established as a Private Natural Heritage Reserve, but the grounding of the property for construction and negligence of local authorities with this fact, threaten the population type of the specie. Conservation recommendations: Establish some form of legal protection in the area where the species occurs, inclusion of species in genus Austrolebias in listings of IUCN and recovery and monitoring of its habitat. Environ Biol Fish (2009) 86:443–444 DOI 10.1007/s10641-009-9544-x

Threatened fishes of the world: Austrolebias univentripinnis Costa and Cheffe 2005 (Cyprinodontiformes: Rivulidae)

Common names: Annual fish, killifish. Conservation status: None. Identification: Urogenital papilla completely attached to anal fin in males, pelvic fins 75 to 90% fused. Largest male registered 35.6 mm SL and largest female 32.2 mm SL (Illustration by Felipe Ribas). Coloration: Lateral body of males with 11–18 vertical rows of brilliant blue-green pigmentation on a dark greenish gray background. Lateral body of females with elongated bars on a faint yellow-brown background (Costa and Cheffe 2005). Distribution: Endemic to Jaguarao River basin, Patos-Mirim Lagoon system, Rio Grande do Sul, Brazil. Abundance: Population estimates not available. Habitat and ecology: Inhabit shallow temporary pools that are formed generally between June to September, in the winter months, during the rainy season. Pools generally are small in surface area (<1,000 m) with maximum depth of 50 cm and high density of aquatic macrophytes. The pH was 6.6–6.8 and the water was whitish. Reproduction: Unknown; likely similar to congenera, which mature within two months after hatching and reproduce throughout his life (Errea and Danulat 2001). Threats: Greatest threat is caused by drainage and changes in physical structure and the hydrological cycle of wetlands due to rice cultivation in floodplains of the Jaguarao River and its small tributaries. The loss of habitat caused by urban progress in the city of Jaguarao and the cattle presence in all sampling sites of the species are also threats to populations of A. univentripinnis (Lanes and Cheffe 2006). Conservation action: None taken. Conservation recommendations: Establish some form of legal protection, as small conservation units, in areas of occurrence of the species; realization of studies regarding the biology and ecology; inhibit the illegal draining and use of wetlands for rice cultivation and urban construction; include it in lists of species of fauna threatened with extinction and recovery and monitoring of its habitat. Environ Biol Fish (2010) 87:319–320 DOI 10.1007/s10641-010-9605-1

Seasonal dynamics in community structure, abundance, body size and sex ratio in two species of Neotropical annual fishes

Seven ephemeral pools on the coastal plain of southern Brazil were found to be inhabited by three annual and 22 non-annual fish species. Two common annual species (Austrolebias minuano and Cynopoecilus fulgens) exhibited clear seasonal dynamics, with the appearance of young fishes in the austral autumn (May to June) and a decline in abundance over the seasonal cycle. The third annual species, Austrolebias wolterstorffii, was rare. No seasonal dynamics were observed in non-annual fishes. The relative abundance of non-annual fishes compared with annual fishes increased over the seasonal cycle, but they coexisted widely. The size structure of annual fishes suggested the presence of a single age cohort in most pools though a second age cohort was registered in one pool in August, coinciding with a large flooding. Strong sexual dimorphism in body size was found in C. fulgens throughout the seasonal cycle, while no sexual dimorphism in body size was found in A. minuano. Female-biased sex ratios were recorded in both common annual fish species in the last three sampling dates (in spring), but not during the first two sampling dates (in winter). The natural lifespan of annual fishes was <8 months. Annual fishes disappeared before habitat desiccation in half of the pools, while non-annual fishes were still present.

The diet of Cynopoecilus fulgens Costa, 2002 (Cyprinodontiformes: Rivulidae) in Southern Brazil wetlands

Abstract Studies with annual fish diet have shown that the generalist habit is a dominant strategy within this group. Cynopoecilus fulgens (Cyprinodontiformes: Rivulidae) is a restricted range species, endemic to a small area in Southern Brazil, and aspects of its biology and ecology are poorly known. The main goal of the study was to determine the diet of C. fulgens throughout its life cycle and compare it with the prey availability in Southern Brazil wetlands. Specifically, we analyzed samples collected in different stages of ontogenetic development (immature and adult fishes) in various year seasons. A total of 52 food items were found in the diet of C. fulgens, and invertebrates comprised 96.4% of the counts observed. The richness of consumed and available prey changed along with the seasons. The seasonal variation of the consumed prey richness was mainly related to increase in fish size along the annual cycle. Microcrustaceans represented 75.6%, 80.9%, and 68.4% of the consumed prey in autumn, winter and spring, respectively. Prey composition varied with the seasons and it was not correlated to prey availability. Diet selectivity was different among male, female and immature fish. Our study reported the feeding habits of Cynopoecilus fulgens to improve knowledge of the biological and ecological traits of annual killifishes in Southern Brazil wetlands, where more than 90% of the original wetlands have been lost due to agricultural expansion.

The fish fauna of the Corrientes stream basin, Patos lagoon system, state of Rio Grande do Sul, southern Brazil

The fish sampled in this study were captured in seasonal collections samplings, conducted between May 2006 and February 2007 in 15 stretches of the Corrientes stream basin, Patos lagoon system, Rio Grande do Sul state, Brazil. A total of 8088 specimens were collected, belonging to nine orders, 24 families and 68 species. In general, the ichthyofauna in this basin has the same pattern recognized for Neotropical rivers with predominance of Characiformes and Siluriformes orders and a high representative of the Characidae and Loricariidae families.

Abundance, sex-ratio, lengthweight relation, and condition factor of non-annual killifish Atlantirivulus riograndensis (Actinopterygii: Cyprinodontiformes: Rivulidae) in Lagoa do Peixe National Park, a Ramsar Site of Southern Brazil

The genus Atlantirivulus was recently established by Costa (2011) to comprise a well supported monophyletic group of killifish species formerly known as Rivulus santensis superspecies (Huber 1992), R. janeiroensis group (Costa 1998), or R. santensis species group (Costa 2004). Presently, Atlantirivulus includes 11 valid species (A. depressus, A. haraldsiolii, A. janeiroensis, A. jurubatibensis, A. lazzarotoi, A. luelingi, A. nudiventris, A. riograndensis, A. santensis, A. simplicis, and A. unaensis) distributed along coastal river basins and lagoons of eastern Brazil (Costa 2008a, b, Costa and De Luca 2009, Costa and Lanes 2009). This genus presents unique morphological features among aplocheiloid fishes, represented by a curved ventral process of angulo-articular and numerous infraorbital neuromasts arranged in a zig-zag pattern ACTA ICHTHYOLOGICA ET PISCATORIA (2012) 42 (3): 247–252 DOI: 10.3750/AIP2011.42.3.09

Pisces, Cyprinodontiformes, Rivulidae, Austrolebias periodicus (Costa, 1999): Distribution extension in state of Rio Grande do Sul, southern Brazil

The present note extends the distribution of annual killifish Austrolebias periodicus , a endangered species, endemic of the Pampas region, in Ibicui River basin, state of Rio Grande do Sul, southern Brazil. This information is needed to develop conservation strategies for this species and its habitat, which are at high risk due to the expansion of rice production and exotic forests in southern Brazil.

Pisces, Perciformes, Eleotridae, Dormitator maculatus (Bloch, 1792): distribution extension for Patos-Mirim lagoon system, state of Rio Grande do Sul, Brazil

We present here the record of Dormitator maculatus (Bloch, 1792) to the Patos-Mirim lagoon system, Rio Grande do Sul, Brazil. This is also the southernmost occurrence in South America, extending species range ca. 150 km from the previously known localities.