Early ontogeny of tetra Markiana nigripinnis (Characiformes: Characidae)

The early development of Markiana nigripinnis is described by morphological characters, pigmentation, and morphometry. Larvae were obtained through semi-natural breeding, collected, fixed, and identified according to their development. Eighty individuals with standard lengths ranging from 3.1 to 24.3 mm were analyzed. Larvae are poorly developed at hatching, with a relatively large yolk sac and finfold. At the preflexion stage, the eyes are pigmented, the mouth and anus are functional, the yolk is completely absorbed, and the pectoral fin bud emerges. At flexion, the first rays of the caudal, anal, and dorsal fins become evident. The pelvic fin bud emerges only at the postflexion stage, in addition to the complete absorption of the finfold. Pigmentation is distributed throughout the body, with a greater concentration on the top of the head, around the mouth, and at the base of the caudal fin. The myomere total number ranged from 34 to 49 (16-23 preanal, and 18-27 postanal). Juveniles show morphological characteristics like adults. The fins ray number are pectoral: 11-13, pelvic: 5-7, dorsal: 8-11, caudal: 16-27, and anal 30-47. The morphometric relationships reveal variations in growth along the early ontogeny of the species.

O desenvolvimento inicial de Markiana nigripinnis foi descrito considerando os caracteres morfológicos, a pigmentação e a morfometria. Indivíduos foram obtidos por meio de reprodução seminatural, coletados, acondicionados, fixados e identificados conforme seu período e estágio de desenvolvimento. Foram analisados 80 indivíduos com comprimento padrão variando de 3,1 a 24,3 mm. As larvas são pouco desenvolvidas à eclosão, com saco vitelino relativamente grande e presença de membrana embrionária. Em pré-flexão, os olhos estão pigmentados, a boca e o ânus são funcionais, o vitelo é completamente absorvido e surge o botão da nadadeira peitoral. Em flexão, os primeiros raios das nadadeiras caudal, anal e dorsal tornam-se evidentes. O botão da nadadeira pélvica aparece somente em pós-flexão, além da completa absorção da nadadeira embrionária. A pigmentação se distribui pelo corpo todo, com maior concentração no topo da cabeça, ao redor da boca e na base da nadadeira caudal. O número total de miômeros variou de 34 a 49 (16-23 pré e 18-27 pós-anal). Os juvenis apresentaram características morfológicas semelhantes ao adulto. O número de raios das nadadeiras é peitoral: 11-13, pélvica: 5-7, dorsal: 8-11, caudal: 16-27 e anal 30-47. As relações morfométricas revelam variações no crescimento ao longo da ontogenia inicial da espécie.

Dynamics of fish larvae recruitment in the hydrographic basin of the Paraguay River in western Brazil

The conservation of fish assemblages depends on the longitudinal and lateral connectivity between riverine habitats, in particular during the breeding season and the initial development. This study investigated the composition and spatio-temporal structure in the ichthyoplankton of the hydrographic basin of the Paraguay River in western Brazil to identify the local spawning grounds and the importance of the longitudinal connectivity of economically valuable migratory species. Data were collected at 10 sites between two breeding seasons (2017/2018 and 2018/2019). Were collected 8,635 larvae, representing 55 taxa in 25 families, including the migratory species Brycon hilarii, Hemisorubim platyrhynchos, Piaractus mesopotamicus, Prochilodus lineatus, Pseudoplatystoma spp., Salminus brasiliensis, Sorubim lima, and Zungaro jahu, which are important fishery resources, with the highest larval densities being recorded between November and January. The Sepotuba, Paraguay, Jauru, and Cabaçal rivers were the areas of greatest connectance, and should thus be considered critical for the conservation of the longitudinal connectivity of this fluvial system, indicating that the migratory species spawn upriver. More efficient fisheries management mechanisms are needed, respecting the spawning period of migratory species, maintaining quality and longitudinal connectivity between habitats, and characteristics necessary for successful larval recruitment.(AU)

A conservação das assembleias de peixes depende da conectividade longitudinal e lateral entre habitats ribeirinhos, em especial durante o período reprodutivo e de desenvolvimento inicial. Objetivou-se avaliar a composição e a estrutura espaço-temporal do ictioplâncton da bacia hidrografia do rio Paraguai no oeste do Brasil para identificar as áreas de desova e a importância da conectividade longitudinal para a reprodução das espécies migradoras de interesse comercial. Os dados foram coletados em 10 pontos entre dois períodos reprodutivos (2017/2018 e 2018/2019). Capturaram-se 8635 larvas, pertencentes a 25 famílias e 55 táxons, incluindo espécies migradoras de interesse comercial, Brycon hilarii, Hemisorubim platyrhynchos, Piaractus mesopotamicus, Prochilodus lineatus, Pseudoplatystoma spp., Salminus brasiliensis, Sorubim lima e Zungaro jahu, que são importantes recursos pesqueiros,com maiores densidades larvais entre novembro e janeiro. Os locais com maiores interações e conectância foram os rios Sepotuba, Paraguai, Jauru e Cabaçal e, portanto, devem ser considerados áreas críticas para a conservação da conectividade longitudinal no sistema fluvial, indicando que as espécies migradoras têm desovado a montante dos locais amostrados. São necessários mecanismos de gestão pesqueira mais eficientes, respeitando o período de desova das espécies migradoras, mantendo a qualidade e conectividade longitudinal entre habitats, características necessárias ao sucesso do recrutamento larval.(AU)

Egg transport and larval behavior of curimba, Prochilodus lineatus (Valenciennes, 1836; Characiformes, Prochilodontidae) in a drift simulator channel

Landscape changes and hydrologic alterations associated with dam construction have greatly hindered reproductive success and the recruitment of migratory species. However, little is known about the flow conditions that are necessary for the reproductive success of migrators. We aimed to analyze one of the important migrants of the Paraná River, the curimba, Prochilodus lineatus(Valenciennes, 1836), to determine the minimum velocities necessary for egg drift and analyze the behavior of larvae at different flow velocities. Thus, we experimentally evaluated the behavior of eggs and larvae released in a drift simulator channel (DSC) under four flow velocities. Additionally, we investigate the swimming ability of larvae in relation to certainmorphometric measures of their bodies. We also performed morphometry and calculations of larval body and fin proportions to determine which structures influence swimming ability. The results indicated that environments with flow velocities greater than 0.081 m s-1were favorable for egg drift and increased the chances of successful transportof eggs to downstream areas. We also observed that soon after hatching, the larvae positioned themselves against the flow, indicating that they had a perception of position and orientation. The larvae were able to maintain and disperse against the flow within the channel 32h after hatching at all velocities, which was mainly due to the development of pectoral and caudal fins that were actively involved in the swimming process, as well as the reduction in the dimensions of the yolk sac, which reduced drag.(AU)

The main channel and river confluences as spawning sites for migratory fishes in the middle Uruguay River

Evidence indicates that migratory fish reproduce in the middle Uruguay River, but the location of spawning sites remains unknown. To identify spawning sites in the basin, fish eggs and larvae were sampled monthly between October 2016 and January 2017. The sampling was carried out in three sections along the middle Uruguay River, covering two environments: the main channel and the mouth of tributaries (Comandaí, Ijuí, and Piratinim rivers). A total of 11,519 eggs and 3,211 larvae were captured, belonged to ten migratory species. Eggs and larvae of migratory fishes, were widely distributed, with predominance of segmented eggs, and larvae in yolk-sac and pre-flexion stages, with higher densities near the confluence with the Piratinim River. Larvae assemblages showed spatial variation, indicating that spawning sites differ among migratory species. This study provides new information about fish reproduction in the middle Uruguay River, revealing that migratory species spawn in different localities along the main channel and tributaries. This region may function as a critical site for fish reproduction, although it is currently threatened by the risk of hydropower expansion, emphasizing the need for measures that preserve their environmental conditions, hydrological connectivity and ecological functions.(AU)

Evidências indicam que os peixes migradores se reproduzem no médio rio Uruguai, mas a localização dos locais de desova ainda permanece desconhecida. Para identificar estes locais, foram realizadas mensalmente entre outubro de 2016 e janeiro de 2017, amostragens de ovos e larvas de peixes em três seções ao longo do médio rio Uruguai, cobrindo dois ambientes: o canal principal e a foz dos afluentes (rios Comandaí, Ijuí e Piratinim). Foram capturados 11.519 ovos e 3.211 larvas, pertencentes a dez espécies migradoras. Ovos e larvas de peixes migradores, foram amplamente distribuídos, com predomínio de ovos segmentados e larvas em estágios de larval-vitelino e pré-flexão, com maiores densidades próximo à confluência com o rio Piratinim. As assembleias de larvas mostraram variação espacial, indicando que os locais de desova diferem entre as espécies migradoras. Este estudo fornece novas informações sobre a reprodução de peixes no médio rio Uruguai, revelando que espécies migradoras desovam em diferentes localidades ao longo do canal principal e afluentes. Esta região pode funcionar como um local crítico para a reprodução de peixes, embora atualmente esteja ameaçada pelo risco de expansão da energia hidrelétrica, enfatizando a necessidade de medidas que preservem suas condições ambientais, conectividade hidrológica e funções ecológicas.(AU)

Larvae of migratory Characiformes species in an archipelago in the Lower Amazon River

In the Amazon basin, most of the migratory Characiformes species represent an important fishing resource for local people. However, the lack of information about the main areas and periods of reproduction and the importance of certain environments for the maintenance of species may jeopardize the renewal of fish stocks. Thus, the aim was to examine the spatial and seasonal variation in the density of larvae of migratory Characiformes species in an archipelago in the Lower Amazon River and to assess the importance of this environment for the biological recruitment of the studied species. The capture of larvae was carried out in places close to restinga swamps, steep ruts,and inlet areas with a plankton net (300 μm) in monthly sampling from January to December 2013. An analysis of variance was used to verify differences in larval density between seasons and sampling months. A total of 30,997 larvae were captured and showed no significant differences in their distributions between habitats. However, a variationbetween the phases of the hydrological cycle was evident, in which the highest larval concentrations were observed during the flooding (17.72 larvae.10m-3) and the drought (1.33 larvae.10m-3). The study area has a great capacity to assist in the maintenance and renewal of regional fish stocks, as it is an important retention and nursery site for larvae of Characiformes that drift along the main channel of the Amazon River.

Larvae of migratory Characiformes species in an archipelago in the Lower Amazon River

In the Amazon basin, most of the migratory Characiformes species represent an important fishing resource for local people. However, the lack of information about the main areas and periods of reproduction and the importance of certain environments for the maintenance of species may jeopardize the renewal of fish stocks. Thus, the aim was to examine the spatial and seasonal variation in the density of larvae of migratory Characiformes species in an archipelago in the Lower Amazon River and to assess the importance of this environment for the biological recruitment of the studied species. The capture of larvae was carried out in places close to restinga swamps, steep ruts,and inlet areas with a plankton net (300 μm) in monthly sampling from January to December 2013. An analysis of variance was used to verify differences in larval density between seasons and sampling months. A total of 30,997 larvae were captured and showed no significant differences in their distributions between habitats. However, a variationbetween the phases of the hydrological cycle was evident, in which the highest larval concentrations were observed during the flooding (17.72 larvae.10m-3) and the drought (1.33 larvae.10m-3). The study area has a great capacity to assist in the maintenance and renewal of regional fish stocks, as it is an important retention and nursery site for larvae of Characiformes that drift along the main channel of the Amazon River.(AU)

Larval fish assemblages in nearshore waters of southeast Gulf of California: vertical and temporal patterns

The influence of salinity and temperature on larval fish assemblages, as well as, temporal and vertical patterns on larval fish assemblages off the inlet of the Presidio River, southeast coast of the Gulf of California were evaluated. Samplings for ichthyoplankton and environmental parameter measurements were carried out at three depths, in five sampling sites, during September and December 1994, and April and June 1995. Anchovies and herrings (Clupeiformes) were the most abundant larval fish accounting for 77% of the total abundance. A significant relationship between salinity and the abundance of larval herrings (Opisthonema medirastre and O. dovii) and between the water temperature and the abundance of the weakfish (Cynoscion reticulatus) was found. Anchovies (Anchoa lucida, A. walkeri, and A. nasus) were present in all sampled months, while O. medirastre and O. dovii occurred in December and June, and C. reticulatus in September. Larvae of pelagic fish were more abundant near the surface, while larvae of demersal fish were more abundant near the bottom. The present study, by emphasising the importance of considering temporal and vertical changes in larval fish assemblages in coastal environments with ecological and economic importance, will be useful for designing more efficient sampling programs.(AU)

Se evaluó la influencia de la salinidad y la temperatura, así como patrones temporales y verticales en la comunidad de larvas de peces enfrente del río Presidio, costa sudeste del Golfo de California. Los muestreos de ictioplancton y las mediciones de los parámetros ambientales fueron realizados a tres profundidades, en cinco sitios de muestreo, durante septiembre y diciembre de 1994, y abril y junio de 1995. Las anchoas y sardinas (Clupeiformes) fueron las larvas de peces más abundantes representando el 77% de la abundancia total. Se encontró una relación significativa entre la salinidad y la abundancia de larvas de sardinas (Opisthonema medirastre and O. dovii), y entre la temperatura del agua y la abundancia de la corvina rayada (Cynoscion reticulatus). Las anchoas (Anchoa lucida, A. walkeri y A. nasus) estuvieron presentes en todos los meses muestreados, mientras que O. medirastre y O. dovii ocurrieron en diciembre y junio, y C. reticulatus en septiembre. Las larvas de peces pelágicos fueron más abundantes cerca de la superficie, mientras que las larvas de peces demersales fueron más abundantes cerca del fondo. El presente estudio, al enfatizar la importancia de considerar los cambios temporales y verticales en el ensamblaje de larvas de peces en ambientes costeros con importancia ecológica y económica, será útil para diseñar programas de muestreo más eficientes.(AU)

Larval fish assemblages in nearshore waters of southeast Gulf of California: vertical and temporal patterns

The influence of salinity and temperature on larval fish assemblages, as well as, temporal and vertical patterns on larval fish assemblages off the inlet of the Presidio River, southeast coast of the Gulf of California were evaluated. Samplings for ichthyoplankton and environmental parameter measurements were carried out at three depths, in five sampling sites, during September and December 1994, and April and June 1995. Anchovies and herrings (Clupeiformes) were the most abundant larval fish accounting for 77% of the total abundance. A significant relationship between salinity and the abundance of larval herrings (Opisthonema medirastre and O. dovii) and between the water temperature and the abundance of the weakfish (Cynoscion reticulatus) was found. Anchovies (Anchoa lucida, A. walkeri, and A. nasus) were present in all sampled months, while O. medirastre and O. dovii occurred in December and June, and C. reticulatus in September. Larvae of pelagic fish were more abundant near the surface, while larvae of demersal fish were more abundant near the bottom. The present study, by emphasising the importance of considering temporal and vertical changes in larval fish assemblages in coastal environments with ecological and economic importance, will be useful for designing more efficient sampling programs.(AU)

Se evaluó la influencia de la salinidad y la temperatura, así como patrones temporales y verticales en la comunidad de larvas de peces enfrente del río Presidio, costa sudeste del Golfo de California. Los muestreos de ictioplancton y las mediciones de los parámetros ambientales fueron realizados a tres profundidades, en cinco sitios de muestreo, durante septiembre y diciembre de 1994, y abril y junio de 1995. Las anchoas y sardinas (Clupeiformes) fueron las larvas de peces más abundantes representando el 77% de la abundancia total. Se encontró una relación significativa entre la salinidad y la abundancia de larvas de sardinas (Opisthonema medirastre and O. dovii), y entre la temperatura del agua y la abundancia de la corvina rayada (Cynoscion reticulatus). Las anchoas (Anchoa lucida, A. walkeri y A. nasus) estuvieron presentes en todos los meses muestreados, mientras que O. medirastre y O. dovii ocurrieron en diciembre y junio, y C. reticulatus en septiembre. Las larvas de peces pelágicos fueron más abundantes cerca de la superficie, mientras que las larvas de peces demersales fueron más abundantes cerca del fondo. El presente estudio, al enfatizar la importancia de considerar los cambios temporales y verticales en el ensamblaje de larvas de peces en ambientes costeros con importancia ecológica y económica, será útil para diseñar programas de muestreo más eficientes.(AU)

Reproductive dynamics of Lycengraulis grossidens (Clupeiformes: Engraulidae) and Platanichthys platana (Clupeiformes: Clupeidae) in a subtropical coastal lagoon / Dinâmica reprodutiva de Lycengraulis grossidens (Clupeiformes: Engraulidae) e Platanichthys platana (Clupeiformes: Clupeidae) em uma lagoa costeira subtropical

We evaluated the reproductive dynamics of two fish species, Lycengraulis grossidens and Platanichthys platana, in a subtropical freshwater coastal lagoon (Peri Lagoon) in Brazil. Samples were collected from nine sites every two months from June 2008 to April 2012. Different fishing methods were used to capture larvae, juveniles, and adults. Limnological variables were obtained using multiparameter probe. More females than males were collected of both fish species and the chi-square test (2) was used to confirm that the sex ratio was female-biased. Large numbers of maturing and mature fishes were observed in almost every sampling month. The gonadosomatic index (GSI) of L. grossidens was the highest in August, October, and December for females and in October for males, and no significant difference was found across years. The GSI of P. platana showed no significant difference across months for either sex; however, significant differences were recorded in year three (June 2010-April 2011) and year four (June 2011-April 2012) for females and in year three (June 2010-April 2011) for males. For both species, GSI was negatively correlated with temperature and water level. L. grossidens larvae were more abundant in October 2010, showing a positive correlation with water transparency, whereas P. platana larvae were more abundant in June 2011, showing a positive correlation with water transparency and negative correlation with temperature and precipitation. Both species were represented by different stages, including larvae, which confirm that these species reproduce in Peri Lagoon. Reproduction was more pronounced in autumn and winter; however, reproductive activity was evident throughout the sampling period. In conclusion, our results show that abiotic factors strongly influence the temporal pattern of reproductive activity and larval assemblages of both L. grossidens and P. platana in Peri Lagoon, Brazil.(AU)

O objetivo do estudo foi avaliar a dinâmica reprodutiva de Lycengraulis grossidens e Platanichthys platana, na lagoa do Peri, uma lagoa costeira de água doce subtropical do Brasil. As amostras foram coletadas a cada dois meses, de junho/2008 a abril/2012 em nove pontos de amostragem. Para a captura de larvas, juvenis e adultos foram utilizados diferentes apetrechos de pesca. As variáveis limnológicas foram obtidas com sonda multiparâmetro. Estatisticamente, mais fêmeas do que machos foram capturadas para as duas espécies baseado no teste de qui-quadrado (2). Grande número de peixes em maturação e maduros foram comuns em quase todos os meses de coleta. O índice gonadossomático (RGS) de L. grossidens variou significativamente apenas entre os meses, sendo mais elevada em agosto, outubro e dezembro para as fêmeas e em outubro para os machos; e não foram encontradas diferenças significativas entre os anos. Não foi encontrado diferença significativa para o RGS de P. platana entre os meses para cada sexo; entretanto, diferenças significativas foram obtidas para as fêmeas no ano três (junho 2010-abril 2011) e quatro (junho 2011-abril 2012) e no ano três (junho 2010-abril 2011) para os machos. Para as duas espécies, o RGS apresentou uma correlação negativa com a temperatura e o nível de água. A distribuição das larvas apresentou variação temporal. As larvas de L. grossidens foram mais abundantes em outubro/2010, apresentando correlação positiva com a transparência da água. As larvas da espécie P. platana foram mais abundantes em junho/2011, apresentando correlação positiva com a transparência da água e negativa com a temperatura e a precipitação. A presença de L. grossidens e P. platana em diferentes estádios de maturação e a ocorrência de larvas confirmou que essas espécies se reproduzem na lagoa do Peri. O período reprodutivo foi mais pronunciado no outono e no inverno, porém a atividade reprodutiva ocorreu durante todo o período de coleta. Em conclusão, nossos resultados mostraram que os fatores abióticos influenciam fortemente o padrão temporal da atividade reprodutiva e a assembleia de larvas da L. grossidens e da P. platana na lagoa do Peri, Brasil.(AU)

Ocurrence and identification of Istiophoridae larvae and Xiphiidae eggs off the Southeastern Brazilian coast / Ocorrência e identificação de larvas de Istiophoridae e ovos de Xiphiidae na costa sudeste brasileira

This study had the aim to identify and relat the occurrence of billfish larvae and eggs in the Southeastern coast of Brazil. During the summer in two seasons (2012/2013 and 2013/2014) 74 surface trawls were done using an ichthyoplankton net off the coast of Vitória-ES, Rio de Janeiro-RJ and Ilhabela-SP and 391 fish larvae were collected. The identification of the billfish larvae was done by molecular biology using the DNA barcode (COI gene). During the 2012/2013 season, five sailfish and two white marlin larvae were identified and in the 2013/2014 season, two sailfishes, two white marlin larvae and two swordfish eggs were identified. The occurrence of billfish larvae shall be further studied, so that inferences about the area and period of spawning and development of early life stages of these fish can be made more accurately.(AU)

O presente estudo teve como objetivo identificar e relatar a ocorrência de larvas e ovos de peixes-de-bico na costa sudeste do Brasil. Durante duas temporadas no verão (2012/2013 e 2013/2014) 74 arrastos de superfície foram feitos utilizando uma rede de ictioplâncton na costa de Vitória-ES, Rio de Janeiro-RJ e Ilhabela-SP, de modo que 391 larvas de peixes foram coletadas. A identificação das larvas de peixes-de-bico foi feita por biologia molecular utilizando o método do DNA barcode (gene COI). Durante a temporada de 2012/2013, foram identificados cinco larvas de agulhões-vela e duas de agulhão-branco. Na temporada 2013/2014, duas larvas de agulhões-branco e duas de agulhões-vela, além de dois ovos de espadarte foram identificados. A ocorrência de larvas de peixes-de-bico deve ser detalhadamente estudada, para que inferências sobre a área e período de desova e desenvolvimento das fases iniciais de vida destes peixes possam ser feitas com mais precisão.(AU)

Ocurrence and identification of Istiophoridae larvae and Xiphiidae eggs off the Southeastern Brazilian coast / Ocorrência e identificação de larvas de Istiophoridae e ovos de Xiphiidae na costa sudeste brasileira

This study had the aim to identify and relat the occurrence of billfish larvae and eggs in the Southeastern coast of Brazil. During the summer in two seasons (2012/2013 and 2013/2014) 74 surface trawls were done using an ichthyoplankton net off the coast of Vitória-ES, Rio de Janeiro-RJ and Ilhabela-SP and 391 fish larvae were collected. The identification of the billfish larvae was done by molecular biology using the DNA barcode (COI gene). During the 2012/2013 season, five sailfish and two white marlin larvae were identified and in the 2013/2014 season, two sailfishes, two white marlin larvae and two swordfish eggs were identified. The occurrence of billfish larvae shall be further studied, so that inferences about the area and period of spawning and development of early life stages of these fish can be made more accurately.

O presente estudo teve como objetivo identificar e relatar a ocorrência de larvas e ovos de peixes-de-bico na costa sudeste do Brasil. Durante duas temporadas no verão (2012/2013 e 2013/2014) 74 arrastos de superfície foram feitos utilizando uma rede de ictioplâncton na costa de Vitória-ES, Rio de Janeiro-RJ e Ilhabela-SP, de modo que 391 larvas de peixes foram coletadas. A identificação das larvas de peixes-de-bico foi feita por biologia molecular utilizando o método do DNA barcode (gene COI). Durante a temporada de 2012/2013, foram identificados cinco larvas de agulhões-vela e duas de agulhão-branco. Na temporada 2013/2014, duas larvas de agulhões-branco e duas de agulhões-vela, além de dois ovos de espadarte foram identificados. A ocorrência de larvas de peixes-de-bico deve ser detalhadamente estudada, para que inferências sobre a área e período de desova e desenvolvimento das fases iniciais de vida destes peixes possam ser feitas com mais precisão.

Influência de El Niño e La Niña nas abundâncias de larvas de peixes migradores em uma região sob influência de barragens

Algumas variáveis ambientais, como a pluviosidade, agem como gatilho para estimular a reprodução de peixes migradores. O El Niño Oscilação Sul (ENOS) é um fenômeno natural que influencia diretamente na intensidade de chuvas, onde na fase negativa (La Niña) as chuvas são geralmente abaixo do normal climatológico e na fase positiva (El Niño) as chuvas são acima do normal, porém os seus efeitos podem ser minimizados devido à presença de barragens nos rios. O objetivo do trabalho foi avaliar a possível relação entre o ENOS e a reprodução de algumas espécies migradoras, através da análise das abundâncias de larvas, em uma região sob influência de barramento. O material analisado foi coletado em 18 pontos da Região do Parque Nacional de Ilha Grande, obtidos entre os anos de 2006 e 2018, divididos em 20 períodos. As coletas foram realizadas com auxílio de redes de plâncton e as larvas capturadas foram identificadas e classificadas. Os dados numéricos do ENOS foram representados pelo Índice Niño Oceânico. A relação entre as densidades de larvas de peixes migradores e os eventos de El Niño e La Niña mostra a influência destes fenômenos sobre as desovas destas espécies, mesmo em um ambiente onde o nível fluviométrico é controlado por barragens, confirmando nossa hipótese. A significância estatística apresentada entre as maiores densidades de captura e o evento El Niño mostram ainda a importância deste fenômeno para a reprodução de peixes migradores, além de apontar a pluviosidade como o principal fator modulatório das desovas destas espécies

Some environmental variables, such as rainfall, act as a trigger to encourage the reproduction of migratory fish. The El Niño Southern Oscillation (ENOS) is a natural phenomenon that directly influences the intensity of rainfall, where in the negative phase (La Niña) the rains are generally below the climatological normal and in the positive phase (El Niño) the rains are above normal , however its effects can be minimized due to the presence of dams in the rivers. The objective of this work was to evaluate the possible relationship between ENSO and the reproduction of some migratory species, through the analysis of larvae abundance, in a region under the influence of a dam. The analyzed material was collected in 18 points of the Ilha Grande National Park Region, obtained between the years 2006 and 2018, divided into 20 periods. The collections were carried out with the aid of plankton nets and the captured larvae were identified and classified. The ENSO numerical data were represented by the Niño Ocean Index. The relationship between migratory fish larvae densities and El Niño and La Niña events shows the influence of these phenomena on the spawning of these species, even in an environment where the fluviometric level is controlled by dams, confirming our hypothesis. The statistical significance presented between the highest capture densities and the El Niño event also show the importance of this phenomenon for the reproduction of migratory fish, in addition to pointing out rainfall as the main modulatory factor in the spawning of these species.

Poluição por fragmentos plásticos flutuantes: abundância, composição e distribuição espacial do séston ao longo da ecoclina estuarina de uma lagoa costeira subtropical

Estudos sobre os padrões espaciais do séston em ambientes estuarinos são de grande importância para entender como se dá a utilização dos recursos disponíveis e como a ação antrópica pode interferir negativamente no mesmo. No presente estudo, o séston estuarino é representado pelo zooplâncton, ictioplâncton (ovos e larvas de peixes) e fragmentos plásticos flutuantes, que sofrem constantes mudanças devido ao gradiente ambiental estuarino, influenciado por graduais alterações das variáveis abióticas locais. Estudos sobre as comunidades zooplanctônica e ictioplanctônica e os fragmentos plásticos se fazem necessários para a lagoa de Santo Antônio dos Anjos (Laguna/SC), ambiente de grande importância ecológica e socioeconômica na região, que vêm sofrendo grandes impactos ambientais. Nessa região, nenhum estudo foi realizado para levantamento de dados a respeito dessas comunidades e também sobre suas fontes poluidoras. Visto isso, o objetivo desse estudo foi realizar a caracterização da composição e distribuição espacial do séston ao longo da ecoclina estuarina da lagoa Santo Antônio dos Anjos. Nos meses de setembro e novembro de 2016, foram realizadas amostragens em 5 diferentes áreas da lagoa de Santo Antônio dos Anjos (3 réplicas por área): A1 (Águas costeiras), A2 (Canal da barra), A3 (Baixo rio Tubarão), A4 (Área central da lagoa) e A5 (Área interna da lagoa). Este estudo surge como uma iniciativa para descrever a distribuição e a interação desses três componentes do ambiente estuarino local, gerando informações importantes para futuros processos de manejo e gestão ambiental.

Studies on the spatial patterns of seston in estuarine environments are of great importance to understand how the available resources are used, as well as how anthropic action can negatively interfere with them. In the present study, estuarine seston is represented by zooplankton, ichthyoplankton (fish eggs and larvae) and floating plastic fragments, which undergo constant changes due to the estuarine environmental gradient, influenced by gradual changes in local abiotic variables. Studies on zooplankton and ichthyoplankton communities and plastic fragments are necessary for the Santo Antônio dos Anjos lagoon (Laguna/SC), an environment of great ecological and socioeconomic importance in the region, which has suffered great environmental impacts. In this region, no study has been done to collect data about these communities and their pollutant sources. Therefore, the objective of this study was to characterize the composition and spatial distribution of seston along the estuarine ecocline of the Santo Antônio dos Anjos lagoon. In the months of September and November 2016, sampling was carried out in 5 different areas of the Santo Antônio dos Anjos lagoon (3 replicates per area): A1 (Coastal waters), A2 (Bar channel), A3 (Lower Tubarão River), A4 (Central area of the lagoon) and A5 (Internal area of the lagoon). This study emerges as an initiative to describe the distribution and interaction of these three components of the local estuarine environment, generating important information for future environmental management processes.

Larvae of migratory fish (Teleostei: Ostariophysi) in the lotic remnant of the Paraná River in Brazil

Fish larvae and adults are morphologically distinct from each other and have different ecological requirements. Research on the dynamics of ichthyoplankton provides valuable information about the early stages of the life cycle of fish. This study analyzed the temporal and spatial distribution of the larval stages of three migratory species - Salminus brasiliensis (Cuvier, 1816), Prochilodus lineatus (Valenciennes, 1836) and Pseudoplatystoma corruscans (Agassiz, 1829) - to identify possible spawning areas in the last lotic remnant of the upper Paraná River, in the Brazilian territory. A total of 26 points were sampled monthly from October 2003 to November 2004. The PERMANOVA detected significant differences between the months only for S. brasiliensis (Pseudo-F = 3.88, p = 0.0021) and P. corruscans (Pseudo-F = 3.35, p = 0.004). Among the environmental variables, temperature was the most important and the Mantel test detected a significant correlation between temperature and the densities, only for P. lineatus (r = 0.09, p = 0.03). The species in our data chose for spawning tributaries that are not dammed, of which most are outside conservation areas. Therefore, recruitment, maintenance and possible actions aiming to recover the stocks of these species are dependent on the conservation of tributaries and floodplain lakes in the region, in addition to monitoring to prevent fishing during the reproductive period.

Mudanças ontogênicas no trato digestório e na dieta de Trachelyopterus galeatus / Ontogenic changes in digestive tract and diet of Trachelyopterus galeatus

In order to analyze aspects of the initial diet of Trachelyopterus galeatus (Linnaeus, 1766) (Pisces, Auchenipteridae) larvae and juveniles were collected monthly between October 2004 and March 2006 in Ivinheima River, MS. To characterize the morphology of the digestive tract (mouth and digestive tract) and diet, individuals were classified in different stages of development, measured and grouped into size classes. The consumed items were identified and grouped by determining the frequency of occurrence and numerical. To summarize the patterns of similarity in diet composition along the ontogenetic development, was implemented in the matrix of the food groups Nonmetric Multidimensional Scaling (NMDS). The difference between size classes (factor) was determined using a Permutation Analysis of Variance (PERMANOVA main test). Larvae of T. galeatus initially present a sub-terminal mouth, reaching terminal in post-flexion and juveniles, suggesting change in foraging position. The differentiation between the stomach and intestine was observed only in flexion stage, coinciding with the transition from endogenous and exogenous feeding. Larvae of class I fed mainly on microcrustaceans and aquatic insects, demonstrating that larvae exploited resources in marginal aquatic vegetation. For the other classes, aquatic insects dominated the diet. The NMDS and PERMANOVA identified differences in dietary compositionbetween the classes more distinct size. Thus, the morphology of the digestive tract, allied to body, presented the initial larvae of T. galeatus limit the capture of food items and therefore influences the composition of the diet.(AU)

Com o objetivo de analisar a ontogenia alimentar de Trachelyopterus galeatus (Linnaeus, 1766) (Pisces, Auchenipteridae), larvas e juvenis foram coletadas entre outubro de 2004 e março de 2006, no rio Ivinheima, MS. Para caracterizar a morfologia do trato digestório (boca e tubo digestório) e a dieta, os indivíduos foram enquadrados em diferentes estágios de desenvolvimento, mensurados e agrupados em classes de tamanho. Os itens consumidos foram identificados e agrupados, determinando-se as frequências numérica e de ocorrência. Para sumarizar os padrões de similaridade na composição da dieta ao longo do desenvolvimento, foi aplicado sob a matriz dos grupos alimentares o Escalonamento Multidimensional Não Métrico (NMDS). A diferença entre as classes de tamanho (fator) foi determinada por Análise de Variância Permutacional (PERMANOVA main test). As larvas de T. galeatus inicialmente apresentam boca subterminal, passando para terminal em pós-flexão e nos juvenis, sugerindo alteração na posição de forrageamento. A diferenciação entre estômago e intestino foi observada somente no estágio de flexão, coincidindo com a transição entre a alimentação endógena e a exógena. As larvas da classe I se alimentaram principalmente de microcrustáceos e insetos aquáticos, demonstrando que as larvas exploraram recursos na vegetação aquática marginal. Para as demais classes, os insetos aquáticos predominaram na dieta. A NMDS e a PERMANOVA identificaram diferenças na composição alimentar entre as classes de tamanho mais distintas. Assim, a morfologia do trato digestório, aliada à corporal, apresentada pelas larvas iniciais de T. galeatus, limitam a captura de itens alimentares e, consequentemente, influenciam a composição da dieta.(AU)

Larvae of migratory fish (Teleostei: Ostariophysi) in the lotic remnant of the Paraná River in Brazil

Fish larvae and adults are morphologically distinct from each other and have different ecological requirements. Research on the dynamics of ichthyoplankton provides valuable information about the early stages of the life cycle of fish. This study analyzed the temporal and spatial distribution of the larval stages of three migratory species - Salminus brasiliensis (Cuvier, 1816), Prochilodus lineatus (Valenciennes, 1836) and Pseudoplatystoma corruscans (Agassiz, 1829) - to identify possible spawning areas in the last lotic remnant of the upper Paraná River, in the Brazilian territory. A total of 26 points were sampled monthly from October 2003 to November 2004. The PERMANOVA detected significant differences between the months only for S. brasiliensis (Pseudo-F = 3.88, p = 0.0021) and P. corruscans (Pseudo-F = 3.35, p = 0.004). Among the environmental variables, temperature was the most important and the Mantel test detected a significant correlation between temperature and the densities, only for P. lineatus (r = 0.09, p = 0.03). The species in our data chose for spawning tributaries that are not dammed, of which most are outside conservation areas. Therefore, recruitment, maintenance and possible actions aiming to recover the stocks of these species are dependent on the conservation of tributaries and floodplain lakes in the region, in addition to monitoring to prevent fishing during the reproductive period.(AU)

Mudanças ontogênicas no trato digestório e na dieta de Trachelyopterus galeatus / Ontogenic changes in digestive tract and diet of Trachelyopterus galeatus

In order to analyze aspects of the initial diet of Trachelyopterus galeatus (Linnaeus, 1766) (Pisces, Auchenipteridae) larvae and juveniles were collected monthly between October 2004 and March 2006 in Ivinheima River, MS. To characterize the morphology of the digestive tract (mouth and digestive tract) and diet, individuals were classified in different stages of development, measured and grouped into size classes. The consumed items were identified and grouped by determining the frequency of occurrence and numerical. To summarize the patterns of similarity in diet composition along the ontogenetic development, was implemented in the matrix of the food groups Nonmetric Multidimensional Scaling (NMDS). The difference between size classes (factor) was determined using a Permutation Analysis of Variance (PERMANOVA main test). Larvae of T. galeatus initially present a sub-terminal mouth, reaching terminal in post-flexion and juveniles, suggesting change in foraging position. The differentiation between the stomach and intestine was observed only in flexion stage, coinciding with the transition from endogenous and exogenous feeding. Larvae of class I fed mainly on microcrustaceans and aquatic insects, demonstrating that larvae exploited resources in marginal aquatic vegetation. For the other classes, aquatic insects dominated the diet. The NMDS and PERMANOVA identified differences in dietary compositionbetween the classes more distinct size. Thus, the morphology of the digestive tract, allied to body, presented the initial larvae of T. galeatus limit the capture of food items and therefore influences the composition of the diet.

Com o objetivo de analisar a ontogenia alimentar de Trachelyopterus galeatus (Linnaeus, 1766) (Pisces, Auchenipteridae), larvas e juvenis foram coletadas entre outubro de 2004 e março de 2006, no rio Ivinheima, MS. Para caracterizar a morfologia do trato digestório (boca e tubo digestório) e a dieta, os indivíduos foram enquadrados em diferentes estágios de desenvolvimento, mensurados e agrupados em classes de tamanho. Os itens consumidos foram identificados e agrupados, determinando-se as frequências numérica e de ocorrência. Para sumarizar os padrões de similaridade na composição da dieta ao longo do desenvolvimento, foi aplicado sob a matriz dos grupos alimentares o Escalonamento Multidimensional Não Métrico (NMDS). A diferença entre as classes de tamanho (fator) foi determinada por Análise de Variância Permutacional (PERMANOVA main test). As larvas de T. galeatus inicialmente apresentam boca subterminal, passando para terminal em pós-flexão e nos juvenis, sugerindo alteração na posição de forrageamento. A diferenciação entre estômago e intestino foi observada somente no estágio de flexão, coincidindo com a transição entre a alimentação endógena e a exógena. As larvas da classe I se alimentaram principalmente de microcrustáceos e insetos aquáticos, demonstrando que as larvas exploraram recursos na vegetação aquática marginal. Para as demais classes, os insetos aquáticos predominaram na dieta. A NMDS e a PERMANOVA identificaram diferenças na composição alimentar entre as classes de tamanho mais distintas. Assim, a morfologia do trato digestório, aliada à corporal, apresentada pelas larvas iniciais de T. galeatus, limitam a captura de itens alimentares e, consequentemente, influenciam a composição da dieta.

Distribuição de ovos e larvas da sardinha-verdadeira na região costeira do estado de Santa Catarina / Distribution of eggs and larvae of Brazilian sardine in the coastal region of Santa Catarina state, Brazil

This study evaluated the spatial distribution of eggs and larvae of Brazilian sardine (Sardinella brasiliensis) in the coastal area of the Santa Catarina State/Brazil, between Itapoá (26S and 48W) and Laguna (28S and 48W) cities. Three surveys were conducted during the sardine spawning season (November/2010, January and March/2011). Sampling occurred in 42 stations, by tripleoblique tows, using a bongo net. Eggs occurred throughout the study area in November, with higher abundance values in the central and north regions, and at northern area in January and March, when it recorded higher temperatures. Larval abundance were higher in the northern region in November and in the central and northern regions in January and March, coinciding with the intrusion of ACAS water mass on the continental shelf, common at this time of the year. Sardinella brasiliensis spawnings occur mainly in sites close to the coast, and after hatching, a larval drift towards ocean region seems to occur.(AU)

Este estudo avaliou a distribuição espacial de ovos e de larvas da sardinha-verdadeira (Sardinella brasiliensis) na área costeira do estado de Santa Catarina/Brasil, entre as cidades de Itapoá (26S e 48W) e Laguna (28S e 48W). Três cruzeiros oceanográficos foram realizados durante o período reprodutivo desta espécie, nos meses de novembro/2010, janeiro e março/2011. As coletas de plâncton foram efetuadas em 42 estações, com o auxílio de rede bongô, em arrastos oblíquos e em triplicata. Os ovos ocorreram em toda a área de estudo no mês de novembro, com maiores valores de abundância nas regiões centro e norte, e na região norte, nos meses de janeiro e março, quando se registraram temperaturas mais altas. As larvas foram mais abundantes na região norte em novembro e nas regiões centro e norte em janeiro e março, coincidindo com o avanço da massa de água ACAS sobre a plataforma, comum nessa época do ano. As desovas de S. brasiliensis nessa região parecem ocorrer, principalmente, nos locais mais próximos à costa, havendo um aparente transporte das larvas em direção à região oceânica.(AU)

Distribuição de ovos e larvas da sardinha-verdadeira na região costeira do estado de Santa Catarina / Distribution of eggs and larvae of Brazilian sardine in the coastal region of Santa Catarina state, Brazil

This study evaluated the spatial distribution of eggs and larvae of Brazilian sardine (Sardinella brasiliensis) in the coastal area of the Santa Catarina State/Brazil, between Itapoá (26S and 48W) and Laguna (28S and 48W) cities. Three surveys were conducted during the sardine spawning season (November/2010, January and March/2011). Sampling occurred in 42 stations, by tripleoblique tows, using a bongo net. Eggs occurred throughout the study area in November, with higher abundance values in the central and north regions, and at northern area in January and March, when it recorded higher temperatures. Larval abundance were higher in the northern region in November and in the central and northern regions in January and March, coinciding with the intrusion of ACAS water mass on the continental shelf, common at this time of the year. Sardinella brasiliensis spawnings occur mainly in sites close to the coast, and after hatching, a larval drift towards ocean region seems to occur.

Este estudo avaliou a distribuição espacial de ovos e de larvas da sardinha-verdadeira (Sardinella brasiliensis) na área costeira do estado de Santa Catarina/Brasil, entre as cidades de Itapoá (26S e 48W) e Laguna (28S e 48W). Três cruzeiros oceanográficos foram realizados durante o período reprodutivo desta espécie, nos meses de novembro/2010, janeiro e março/2011. As coletas de plâncton foram efetuadas em 42 estações, com o auxílio de rede bongô, em arrastos oblíquos e em triplicata. Os ovos ocorreram em toda a área de estudo no mês de novembro, com maiores valores de abundância nas regiões centro e norte, e na região norte, nos meses de janeiro e março, quando se registraram temperaturas mais altas. As larvas foram mais abundantes na região norte em novembro e nas regiões centro e norte em janeiro e março, coincidindo com o avanço da massa de água ACAS sobre a plataforma, comum nessa época do ano. As desovas de S. brasiliensis nessa região parecem ocorrer, principalmente, nos locais mais próximos à costa, havendo um aparente transporte das larvas em direção à região oceânica.

TRANSPORTE DE OVOS E COMPORTAMENTO LARVAL DE Prochilodus lineatus (VALENCIENNES, 1836) EM CANAL SIMULADOR DE DERIVA

Este estudo teve por objetivo avaliar a deriva dos ovos e o comportamento de larvas de corimba (Prochilodus lineatus VALENCIENNES, 1836) frente diferentes velocidades de fluxo em um canal simulador de deriva (CSD). Para o experimento foram determinadas as velocidades de fluxo, sendo, 0,032 m/s, 0,044 m/s, 0,068 m/s e 0,081 m/s. Os ovos e larvas utilizados foram obtidos de desovas induzidas e acondicionados em incubadora cônicocilíndrica de fibra de vidro de 200 litros, com circulação constante de água, à uma temperatura média de 21,6ºC. Os ovos passaram pelo canal a cada 4 horas e as larvas a cada 8 horas a partir da eclosão, até atingirem 16 horas de desenvolvimento então, os testes passaram a ser efetuados em intervalos de 12 horas. Nas amostragens foram utilizados 10 indivíduos (réplicas) para cada uma das 4 velocidades de fluxo testadas, onde se observou a velocidade e a distância de transporte e o comportamento natatório das larvas. O transporte dos ovos de P. lineatus durante o experimento foi proporcional ao aumento do fluxo, ficando em sua maioria próxima à superfície. Logo após a eclosão as larvas já procuraram se posicionar contra o fluxo dentro do canal indicando que mesmo pouco desenvolvidas tem a percepção de posição e orientação. As maiores velocidades de transporte das larvas ocorreram nos tempos inicias de desenvolvimento, sendo completamente transportadas ou seguindo o sentido do fluxo (reotaxia negativa). Desta maneira, baseado nos dados obtidos neste estudo, podemos concluir que ambientes cuja velocidade de fluxo seja inferior a 0,044 m/s não são favoráveis à deriva de ovos de P. lineatus, enquanto que velocidades acima de 0,081 m/s proporcionam maiores probabilidades de sucesso no transporte dos ovos para as áreas à jusante. Podemos concluir ainda que as larvas apresentaram comportamento ativo desde as primeiras horas de desenvolvimento com comportamento similar ao apresentado em ambiente natural e que a partir de 48 horas pós-eclosão já são capazes de se manterem e dispersarem contra o fluxo dentro do canal.

The objective of this study was to evaluate the egg drift and the behavior of corimba larvae (Prochilodus lineatus VALENCIENNES, 1836) against different flow velocities in a drift simulator channel (DSC). For the experiment, the flow velocities were determined, being: 0.032 m/s, 0.044 m/s, 0.068 m/s and 0.081 m/s. The eggs and larvae used in the experiment were obtained from induced spawning and stored in a 200 liter conical-cylindrical fiberglass incubator with constant water circulation, at an average temperature of 21.6ºC. The eggs passed through the canal every 4 hours and the larvae every 8 hours from hatching until they reached 16 hours of development. Tests were then performed at 12-hour intervals. In the samples, 10 individuals (replicates) were used for each of the 4 flow velocities tested, where the speed and the transport distance and the swimming behavior of the larvae were observed. The transport of P. lineatus eggs during the experiment was proportional to the increase of the flow, being mostly near the surface. Soon after hatching, the larvae have already tried to position themselves against the flow within the canal, indicating that even the poorly developed ones have position and orientation perception. Larger transport velocities occurred during early developmental periods, being completely transported or following the direction of flow (negative reotaxis). Thus, based on the data obtained in this study, we can conclude that environments whose flow velocity is less than 0.044 m/s are not favorable for P. lineatus egg drift, while velocities above 0.081 m/s provide higher probabilities of successfully transporting eggs to downstream areas. We can also conclude that the larvae showed active behavior from the first hours of development with behavior similar to that presented in a natural environment and that after 48 hours after hatching they are able to maintain and disperse against the flow within the channel.