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ABSTRACT Species distribution modeling (SDM) studies of aquatic macrophytes are still attached to methodological paradigms focused on terrestrial plants, such as the use of bioclimatic layers. Our goal was to evaluate the applicability of this paradigm based on a SDM study of Egeria densa, Pontederia crassipes, and Salvinia auriculata in the São Francisco river, Brazil. We compared performances of optimizations of computed models using AUC and TSS with distribution records of these species and bioclimatic layers, or limnological layers generated from the interpolation of data obtained in the field. We calculated models using six algorithms. The models calculated using layers of limnological variables had higher performances than did those calculated using layers of bioclimatic variables, except when the Maximum Entropy Default algorithm was used. We attribute these results to the specificities of the data obtained to develop the limnological layers, such as observations obtained in different habitats of the river and during different hydrologic periods. We conclude that the use of bioclimatic layers, a methodological paradigm traditionally used for SDM of aquatic macrophytes, can be questionable for some situations, such as in investigations at local and regional scales.

ABSTRACT Surf zones are important for early life stages of several fish species for presenting characteristics such as high phytoplanktonic production, diverse food availability and shelter against predators. The action of waves in this environment provides nutrient cycling and increase the turbidity making surf zones ideal nursery environments for diverse species of fish, including clupeiforms. Clupeiform species have a great ecological and economic value for being abundant fish in tropical sandy beaches surf zones with significant fisheries importance. Studies about their feeding ecology and environment use are relevant, and one of the methods improving this knowledge is the application of ecomorphological analyses, which helps understanding species ecological interactions and their adaptations. In this context, the present study aimed to identify the ecomorphological relations and infer about the feeding ecology of eight sympatric clupeiform species in a Brazilian tropical sandy beach. Ten ecomorphological variables were analyzed of individuals belonging to the species Anchoa tricolor (Spix & Agassiz, 1829), Anchoa januaria (Steindachner, 1879), Anchovia clupeoides (Swainson, 1839), Anchoviella lepidentostole (Fowler, 1911), Lycengraulis grossidens (Spix & Agassiz, 1829), Chirocentrodon bleekerianus (Poey, 1867), Harengula clupeola (Cuvier, 1829) and Opisthonema oglinum (Lesueur, 1818), whose values were employed in a principal component analysis (PCA) with the two first axis explaining 58.92% of the total variance. A high morphological overlap between the species of Engraulidae was observed with the exception of A. clupeoides, which differed from the others for presenting higher values of the compression index and caudal peduncle compression index. The Clupeidae species differed from the other families due to higher values of relative height and relative head length which also showed differences between the species themselves, having H. clupeola presented the highest values of these variables. The representative of Pristigasteridae showed an intermediate overlap between the species of the other families because of its highly compressed body but with low scores of relative height, caudal peduncle relative length and mouth aspect ratio. The morphological differentiation between the families and even between species from the same family indicates niche divergences, showing that besides their phylogenetical proximity there are differences in their ecological interactions which possibly contribute to their coexistence.

A 42-day trial was conducted to evaluate the effects of a low-salinity biofloc system with different stocking densities on water quality and zootechnical performance of Nile tilapia fingerlings (10 g/L). Four treatments were tested at different densities: 500 fish/m³, 750 fish/m³, 1,000 fish/m³ and 1,250 fish/m³, all in triplicate. Fingerlings of Oreochromis niloticus (initial mean weight of 1.17 ± 0.05 g) were stocked in twelve experimental black-plastic tanks (40 L) with no water exchange during the experimental period. Molasses was added daily to the system at 30% of the amount of feed, and fish were given four daily rations of a formulated feed composed of 36% crude protein and 9% lipids. Water quality variables (dissolved oxygen, pH, salinity, TAN, NO2, NO3 and PO43) did not demonstrate significant differences between the treatments. However, significant influences (α ≤ 0.05) of the stocking densities were observed for total suspended solids, settleable solids, final weight, yield, and protein efficiency ratio. The results showed survival over 96%, final weight values between 12 and 18 g, yield between 9.49 and 15.27 kg/m3, water consumption of 52 to 101 L/kg fish, and total time of settling chambers between 238 and 305 h/kg fish. These results indicate a negative effect of stocking density on final weight, survival, alkalinity, NO2, PO43 and water consumption, and a positive effect on yield in Nile tilapia fingerling culture (1-20 g) in a low-salinity biofloc system with densities up to 1000 fish/m³.

Biosurfactants can be used in environmental pollution control systems for oil spill and its derivatives, since they increase the bioavailability of contaminants by reducing the surface tension of water. The mollusk Anomalocardia brasiliana is a species that inhabits areas with little suspended material. The aim was to test the tolerance concentration and the median lethal concentration (LC50) for a period of 96h through survival. The experiment was conducted at UFRPE, and the biosurfactant produced the root Candida lipolytica, having an industrial waste as a source of carbon, plus mineral medium. The animals were not fed for 24 hr prior to the experiment. It was performed six treatments (1:10, 1:20, 1:40, 1:80 and 1: 160) in three replicates, with the density of 2.5 individual / Litre and subjected to constant aeration at a temperature of 26 ± 0 5 ° C and salinity 26. It follows that the treatments 1 (1:10) and 2 (1:20) gave a survival 76.18%, however treatments 3 (95.23%) and 4 (95 83%) were higher and treating with 5 to 100%. The LC50 estimated for the biosurfactant tested was 0.222 or 1: 4.5. The compound is lethal to the test organism used in dilutions being suggested further experiments with dilutions from 1: 05 to 1:20, to better estimate of LC50 for the same species. Thus, a better understanding of the lethal concentration in organisms representing different trophic levels brings positive results to optimize the procedures in environmental monitoring in port areas.

A trial was conducted for 42 days to evaluate the effects of two commercial feeds with high and low crude protein content on the performance of white shrimp Litopenaeus vannamei cultivated in an integrated biofloc system with the seaweed Gracilaria birdiae. The experiment had a 2 × 2 factorial design (a biofloc monoculture or an integrated system with 32% (low) or 40% (high) crude protein content) with the following treatments: IS32 (an integrated system using low protein commercial feed); IS40 (an integrated system using high protein commercial feed); M32 (a monoculture system using low protein commercial feed); and M40 (a monoculture system using high protein commercial feed), all in triplicate. Shrimp individuals (0.23 ± 0.04 g) were stocked at a density of 500 shrimp/m3 and no water exchange was carried out during the experimental period. No significant influence (p > 0.05) was found to be caused by the integrated system or the crude protein levels on water quality. However, a significant influence (p < 0.05) was found for final weight (3.21–4.12 g), weight gain (2.97–3.89 g), yield (1.39–1.96 kg/m3) and feed conversion ratio (1.47–1.74). Growth was similar in IS32, M40 and IS40, indicating that crude protein levels can be reduced with no adverse effect on shrimp performance variables in integrated biofloc systems with G. birdiae.

A Região Neotropical possui um elevado número de espécies de peixes de água doce, cujas adaptações para explorar diferentes tipos de alimento é particularmente evidente em reservatórios, refletindo numa considerável plasticidade alimentar. Characiformes é a mais diversificada ordem de peixes da região, tendo Anostomidae como uma das famílias mais especiosas, com destaque para Leporinus, com cerca de 80 espécies válidas. Embora suas espécies sejam consideradas primordialmente onívoras, algumas apresentam dieta herbívora, e a plasticidade alimentar do gênero é uma característica comum em ambientes sujeitos a variação sazonal de nível da água. No presente trabalho, são analisadas a composição da dieta de Leporinus reinhardtii Lütken, 1875 no reservatório de Sobradinho e a influência da variação sazonal de seu nível sobre a mesma ao longo de três ciclos anuais (2006-2009). Dentre os 876 indivíduos analisados, 302 foram coletados no período de seca e 574 no de cheia. A dieta foi composta por 47 itens, agrupados em nove categorias: Moluscos, Microcrustáceos, Insetos, Insetos (partes), Chironomidae, Vegetais, Sementes, Sedimento e Outros. Chironomidae representou em média 60% do peso total das categorias alimentares, seguido de Sementes com 25% e as demais categorias com menos de 10%. No período de cheia, nos trechos lêntico e de transição, predominaram Sementes na dieta, tendo Chironomidae sido mais representativa no trecho lótico, e as demais categorias não ultrapassando 20% de participação nos três trechos neste período. No período de seca, houve diferença nos itens predominantes, com predominância de Insetos no trecho lêntico, principalmente Coleoptera, e de Vegetais no lótico, com maior participação de macrófitas aquáticas, algas filamentosas, clorofíceas e da diatomácea Oscillatoria. Já no trecho de transição, Microcrustáceos dominaram na dieta, diferindo dos demais trechos. A dieta de L. reinhardtii se caracterizou por baixos valores de frequência de ocorrência de todas as categorias alimentares (predominantemente inferiores a 50%) e elevada abundância relativa (>80%) de diferentes categorias. A amplitude de nicho foi restrita nos diferentes trechos nos dois períodos, sendo ligeiramente mais elevada na cheia, devido à maior diversidade de itens, em particular no trecho lêntico. Leporinus reinhardtii possui hábito onívoro com comportamento especialista no reservatório de Sobradinho, cujas categorias predominantes da dieta dependem do regime hidrológico do reservatório e das características ambientais de cada trecho, refletindo numa amplitude restrita de nicho trófico para a espécie.

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of gpeixe-cachorroh species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, andTetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (Că = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (Că = 0.427) and drought (Că = 0.172) seasons, in the lotic (Că = 0.434), transition (Că = 0.089) and lentic (Că = 0) stretches, and in overall overlap (Că = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.Estudos sobre a dieta de peixes contribuem para o entendimento dapartilha de recursos e da estrutura trofica da comunidade. O presente trabalho caracteriza a dieta dos peixes-cachorro Acestrorhynchus britskii e A. lacustris no reservatorio de Sobradinho, Estado da Bahia. Coletas bimestrais noturnas (Novembro/2006 a Julho/2008) foram efetuadas nos trechos lotico, transicao e lentico do reservatorio, empregando redes de espera. Foram analisados 899 estomagos de A. britskii e 476 de A. lacustris, aproximadamente 70% dos quais se encontravam vazios. Seu conteudo evidenciou tratar-se de especies predominantemente piscivoras, com 18 peixes-presa identificados. Entretanto, cada presa ocorreu num unico mes, exceto Anchoviella vaillanti, registrada em 80% dos meses para A. bristski e Tetragonopterus chalceus em 25% deles para A. lacustris. As especies apresentaram elevada sobreposicao alimentar (Că = 0,992), pela ocorrencia de Actinopterygii (partes) e Actinopterygii nao-identificado em todos os meses. Entretanto, considerando apenas os peixespresa, foi observado consumo diferenciado e menor sobreposicao alimentar, nos periodos de cheia (Că = 0,427) e seca (Că = 0,172), nos trechos lotico (Că = 0,434), de transicao (Că = 0,089) e lentico (Că = 0), e na sobreposicao geral (Că = 0,236). A diferenca espacial e sazonal no consumo de peixes-presa distintos pelas duas especies sugere habito alimentar oportunista e mecanismo dereducao da competicao pelos recursos alimentares.

The present study aims to compare the buccal apparatus and gastrointestinal tract of early life stages of Centropomus undecimalis (Bloch, 1792), and relate them to its diet. A total of 190 individuals collected with a channel net in the Catuama estuary (07º40'9.9''S, 34º50'36.7''W), northern coast of the state of Pernambuco, were examined. Morphometrical and meristic data were analyzed for the two initial developmental periods (larval and juvenile). Their digestive tube was morphologically characterized and its content identified. The longest transverse axis of food items was measured, and compared to the standard length (SL) and mouth gape size (D) of the individuals. Body measurement regressions differed significantly (p

Um estudo da distribuição fotoperiódica e sazonal das zoeas de Brachyura foi realizado no estuário do Rio Jaguaribe, Pernambuco, Brasil. Amostras de plâncton foram obtidas bimestralmente, durante o ano de 2001, em diferentes marés e nos períodos noturno e diurno em duas estações de coleta. Foram identificados 14 táxons, onde a família Ocypodidae, representada pelas larvas de Ucides cordatus (Linnaeus, 1763) e Uca spp., foi a mais abundante, seguida de Xanthidae e Grapsidae. Na estação próxima à foz, os táxons estiveram bem distribuídos, além de ter apresentado um maior número de famílias identificadas. As larvas de Ocypodidae, Grapsidae e Morfotipo B indicaram um movimento de dispersão para áreas costeiras, enquanto que os Pinnotheridae indicaram uma provável retenção nas águas do estuário. A elevada ocorrência de zoeas no primeiro estágio larval reforça o importante papel dos estuários como berçários para diversas espécies de crustáceos.A survey regarding the diel and seasonal distribution of brachyuran zoea was accomplished in the Jaguaribe estuary, state of Pernambuco, Brazil. Plankton samples were obtained bimonthly, throughout the year of 2001, in different tides and during day and night periods, at two sampling stations. Fourteen taxa were identified, among which Ocypodidae, represented by Ucides cordatus (Linnaeus, 1763) and Uca spp. zoea, was the most abundant one, followed by Xanthidae and Grapsidae. In the station close to the estuary opening, the taxa were well distributed, besides presenting a larger number of identified families. Ocypodidae, Grapsidae and Morphotype B zoea indicated a dispersion movement into coastal areas, while Pinnotheridae indicated a probable retention within the estuarine waters. The high occurrence of zoea in the first larval stages reinforces the important role of estuaries as nursery grounds for several crustacean species.

Besides its extreme climate conditions, the Caatinga (a type of tropical seasonal forest) hosts an impressive faunal and floristic biodiversity. In the last 50 years there has been a considerable increase in the number of studies in the area. Here we aimed to present a review of these studies, focusing on four main fields: vertebrate ecology, plant ecology, human ecology, and ethnobiology. Furthermore, we identify directions for future research. We hope that the present paper will help defining actions and strategies for the conservation of the biological diversity of the Caatinga.

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of “peixe-cachorro” species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, and Tetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (Cλ = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (Cλ = 0.427) and drought (Cλ = 0.172) seasons, in the lotic (Cλ = 0.434), transition (Cλ = 0.089) and lentic (Cλ = 0) stretches, and in overall overlap (Cλ = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.

The present study describes the external morphology and morphometry of the initial development of Atherinella brasiliensis, and contributes toward broadening knowledge on its biology. A total of 88 larvae and 14 juveniles were used to characterize the morphological development and analyze body proportions. Fish with standard lengths (SL) from 1.4 to 77 mm were used in the study. Larvae hatch at an average of 1.4 mm SL. In the preflexion stage, the larval body is enveloped by a finfold, which begins behind the head. Pectoral fins are the first to be formed and preflexion larvae have four characteristic dendritic chromatophores on the head. The flexion stage begins at an average of 4.4 mm SL; dorsal and anal fins already exhibit pterygiophores and a terminal, somewhat up-turned mouth. At 6.8 mm SL, the flexion stage ends. In the postflexion stage, larvae present greater ossification of the dorsal and anal fin rays, exhibit pelvic fin buds and a darkening of lateral pigmentation. At an average of 8.8 mm SL, head pigmentation intensifies and pelvic fins exhibit conspicuous ossifying rays. Larvae at 11.8 mm SL have all fins formed; the second dorsal fin is the last to be formed at an insertion point posterior to the anal fin. The juvenile period begins at approximately 12 mm SL. At this stage, A. brasiliensis has an anal fin located at the median portion of the body and the posterior end of pectorals surpasses the origin of pelvic fins, which are located at the midpoint between the pectoral and anal fins. Scales are present on the dorsal-lateral region behind the head. The morphological features of A. brasiliensis herein described allow an adequate identification of its larvae and differentiate them from hemiramphid and other atheriniform larvae, thus broadening knowledge on the larval biology of the species.

The considerable similarity in the early life stages of different fish species makes egg and larvae identification in fishery biology and ichthyoplankton surveys a difficult task. Knowledge on early larval development of morphologically similar taxa and species-rich orders, such as Clupeiformes, mainly in the Neotropical fresh waters is rather limited. The aim of the present study was to describe morphological and meristic aspects of the larvae and early juveniles of Anchoviella vaillanti, an endemic species of the São Francisco River basin in Brazil. The characterization was based on an ontogenetic series of 132 individuals (1.3-51.0 mm SL). In the larval period, body varies from elongated to very elongated and the head is small, which is typical of Clupeiformes. The finfold is present beginning in the yolk-sac stage, when larvae have a large yolk sac, until the flexion stage. Pectoral fin buds are the first to form during the preflexion stage, when dorsal- and anal-fin pterygiophores and hypural bones are first visible. The total vertebra count ranges from 36 to 39 and the myomere number ranges from 31 to 45. Complete fin formation obeys the following sequence: anal and dorsal fins during flexion stage; and pectoral, pelvic and caudal fins during postflexion stage. Despite being the only freshwater clupeiform representative in the São Francisco River, A. vaillanti may occur sympatrically with A. lepidentostole in the lower stretches of the river basin. Although early larvae characteristics of A. lepidentostole are not known, its late larvae and early juveniles may be distinguished from those of A. vaillanti, by the higher number of dorsal-fin rays (15 or 16 vs. 12 or 13 in A. vaillanti), higher total vertebra count (40 vs. 37 to 40) and shorter pre-pectoral length (14 to 16 vs. 22.8 to 28.9% SL).

Resumo O presente estudo teve por objetivo avaliar a riqueza, formas biológicas e composição florística de macrófitas aquáticas ao longo do eixo rio-barragem de um reservatório no Nordeste do Brasil. Foram estabelecidas seis estações de amostragem ao longo de suas regiões lótica, de transição e lêntica. As coletas ocorreram nos meses de junho e julho de 2008 (período de estiagem), e em janeiro e fevereiro de 2009 (período chuvoso). Foram coletados indivíduos em estagio fértil ou vegetativo, tendo as espécies sido categorizadas quanto às formas biológicas e os percentuais de frequência de ocorrência. A similaridade florística entre os pontos de amostragem foi calculada utilizando-se o índice de Jaccard. Foram identificadas 43 espécies, das quais 18 estiveram presentes na região lótica, 16 na de transição e 25 na lêntica. Salvinia auriculata Aubl. e Paspalum repens P.J. Bergius ocorreram em 100% das unidades amostrais. As regiões lótica e de transição contemplaram, predominantemente, espécies anfíbias e emergentes, diferindo da região lêntica, onde espécies flutuantes, emergentes e submersas foram mais evidentes. A similaridade entre os ecossistemas lótico e de transição foi maior que 50%, enquanto que entre esses ambientes e a região lêntica foi menor que 25%.

ABSTRACT: Prochilodus argenteus is an endemic fish species from the São Francisco River basin that is of high economic and environmental importance. The present study aimed to contribute with information to the taxonomic identification of larvae and juveniles of this species. Larvae , obtained from induced spawning of wild animals, were reared in ponds. Individuals were collected daily and classified into larval stages or juvenile phase. Morphological descriptions and morphometric measurements were performed, together with a piece wise linear regression analysis of the body proportions throughout the development process. Individuals in the preflexion stage had a standard length (SL) of 4.48 to 6.64mm, long to moderate body (BH/SL), small to moderate head (HL/SL), and a small to moderate eye (ED/HL). In the flexion stage, the SL varied from 6.60 to 11.00mm, long to moderate body, moderate head, and small to moderate eye. Larvae in the postflexion stage presented SL of 10.54-19.93mm, moderate body, moderate to big head and small eye. The juvenile phase included specimens with a SL of 18.27 to 42.21mm which presented a moderate to high body, big head and small to moderate eye. Regression analysis showed significant moments of change in rate of increase of the body proportions, presenting a change in the growth pattern from allometry to isometry during the early development.