Reproductive aspects of the prawn Macrobrachium amazonicum in a continental population living downstream of a hydroelectric dam / Aspectos reprodutivos do camarão dulcícola Macrobrachium amazonicum em uma população vivendo a jusante da barragem de uma usina hidrelétrica

The migratory behavior of females of the freshwater prawn Macrobrachium amazonicum(Heller, 1862) can indicate a strategy that optimizes the population establishment. With this idea in mind, we evaluated the reproductive biology of M. amazonicum, hypothesizing that females were evenly distributed downstream of Hydroelectric Dam. Specimens were collected monthly for one year, from six sites of Rio Grande river. The specimens were sexed and measured (carapace length; CL). A total of 14,697 adults were captured, 2,864 males (AM), 11,082 non-breeding females (AF) and 751 breeding females (BF). The smallest BF had 3.8 mm CL. The distribution of demographic groups was assessed by a Principal Component Analysis (PCA), which explained 95.16% of the distribution over the collection sites. Breeding females were more abundant in the sites closest to the dam. This result can be explained by rainfall, which varied significantly throughout the year. As the breeding females migrated upstream toward the dam and were more abundant there, our hypothesis of homogeneous distribution was rejected. This behavior probably optimizes larval dispersion. The reproduction was continuous with peaks in the period preceding the maximum rainfall.

O comportamento migratório das fêmeas de Macrobrachium amazonicum (Heller, 1862) pode revelar estratégias para otimizar o estabelecimento da população. Com essa ideia em mente, avaliamos a biologia reprodutiva de M. amazonicum, hipotetizando que as fêmeas estavam uniformemente distribuídas a jusante da Usina Hidrelétrica. Os espécimes foram coletados mensalmente durante um ano, em seis localidades do Rio Grande, identificados quanto ao sexo e tiveram mensurado o comprimento da carapaça (CL). Foram capturados 14.697 camarões adultos, sendo 2.864 machos (AM), 11.082 fêmeas não-ovígeras (AF) e 751 fêmeas embrionadas (BF). A menor fêmea BF possuía 3,8 mm CL. A distribuição dos grupos demográficos foi avaliada por uma Análise de Componentes Principais (PCA), a qual explicou 95,16% da distribuição ao longo dos pontos de coleta (BF mais próximas da barragem). Tal explicação provavelmente foi relacionada com a precipitação, a qual variou significativamente ao longo do ano. Nossa hipótese de distribuição homogênea foi rejeitada, uma vez que as fêmeas ovígeras sobem o rio até as proximidades da barragem, provavelmente para otimizar a dispersão das larvas. A reprodução foi contínua com picos em períodos que antecedem os valores máximos de precipitação.

Reproductive aspects of the prawn Macrobrachium amazonicum in a continental population living downstream of a hydroelectric dam / Aspectos reprodutivos do camarão dulcícola Macrobrachium amazonicum em uma população vivendo a jusante da barragem de uma usina hidrelétrica

The migratory behavior of females of the freshwater prawn Macrobrachium amazonicum(Heller, 1862) can indicate a strategy that optimizes the population establishment. With this idea in mind, we evaluated the reproductive biology of M. amazonicum, hypothesizing that females were evenly distributed downstream of Hydroelectric Dam. Specimens were collected monthly for one year, from six sites of Rio Grande river. The specimens were sexed and measured (carapace length; CL). A total of 14,697 adults were captured, 2,864 males (AM), 11,082 non-breeding females (AF) and 751 breeding females (BF). The smallest BF had 3.8 mm CL. The distribution of demographic groups was assessed by a Principal Component Analysis (PCA), which explained 95.16% of the distribution over the collection sites. Breeding females were more abundant in the sites closest to the dam. This result can be explained by rainfall, which varied significantly throughout the year. As the breeding females migrated upstream toward the dam and were more abundant there, our hypothesis of homogeneous distribution was rejected. This behavior probably optimizes larval dispersion. The reproduction was continuous with peaks in the period preceding the maximum rainfall.(AU)

O comportamento migratório das fêmeas de Macrobrachium amazonicum (Heller, 1862) pode revelar estratégias para otimizar o estabelecimento da população. Com essa ideia em mente, avaliamos a biologia reprodutiva de M. amazonicum, hipotetizando que as fêmeas estavam uniformemente distribuídas a jusante da Usina Hidrelétrica. Os espécimes foram coletados mensalmente durante um ano, em seis localidades do Rio Grande, identificados quanto ao sexo e tiveram mensurado o comprimento da carapaça (CL). Foram capturados 14.697 camarões adultos, sendo 2.864 machos (AM), 11.082 fêmeas não-ovígeras (AF) e 751 fêmeas embrionadas (BF). A menor fêmea BF possuía 3,8 mm CL. A distribuição dos grupos demográficos foi avaliada por uma Análise de Componentes Principais (PCA), a qual explicou 95,16% da distribuição ao longo dos pontos de coleta (BF mais próximas da barragem). Tal explicação provavelmente foi relacionada com a precipitação, a qual variou significativamente ao longo do ano. Nossa hipótese de distribuição homogênea foi rejeitada, uma vez que as fêmeas ovígeras sobem o rio até as proximidades da barragem, provavelmente para otimizar a dispersão das larvas. A reprodução foi contínua com picos em períodos que antecedem os valores máximos de precipitação.(AU)

Diversity and structure of the stomatopod (Crustacea) community on the Amazon continental shelf

The present study aimed to characterize the biodiversity of the Stomatopoda species found off the coast of the northern Brazilian states of Amapá and Pará, within the region's Exclusive Economic Zone. Two distinct sectors were surveyed, to the north and to the south of Cape Norte. The specimens were collected during fishery surveys carried out between 1996 and 1998 by the Revizee Program, using bottom shrimp trawl nets. The specimens were identified at the Crustaceans Laboratory of the Center for Research and Management of Fishery Resources of the Northern Coast and the Carcinology Laboratory of the Federal Rural University of Pernambuco. The 189 identified specimens represented Lysiosquilla scabricauda (Lamarck, 1818) (n = 2), Parasquilla meridionalis Manning, 1916 (n = 1), Squilla empusa Say, 1818 (n = 6), and Squilla lijdingi Holthuis, 1959 (n = 180). Only three species were collected in each of the survey sectors, with L. scabricauda and S. lijdingi being captured in both sectors. Squilla lijdingi was dominant in both sectors, whereas the other species were considered to be rare. Squilla lijdingi was very frequent in the northern sector, although the other stomatopods were infrequent. In the southern sector, L. scabricauda was sporadic, S. empusa was frequent, and S. lijdingi was very frequent. A significant difference was observed in the number of specimens captured in both sectors. The Shannon index was 0.6144 bits.ind-1 for the northern sector and 0.2708 bits.ind-1 for the southern one, whereas equitability was 0.3876 in the North and 0.1708 in the South. The stomatopods were collected at depths between 32 and 109 m, and were captured primarily on gravelly bottoms in the northern sector, and on muddy substrates in the southern sector. Stomatopods were more abundant in the northern sector during the dry season from June to November, whereas they were more common in the South during rainy season, from December to May.

Diversity and structure of the stomatopod (Crustacea) community on the Amazon continental shelf

The present study aimed to characterize the biodiversity of the Stomatopoda species found off the coast of the northern Brazilian states of Amapá and Pará, within the region's Exclusive Economic Zone. Two distinct sectors were surveyed, to the north and to the south of Cape Norte. The specimens were collected during fishery surveys carried out between 1996 and 1998 by the Revizee Program, using bottom shrimp trawl nets. The specimens were identified at the Crustaceans Laboratory of the Center for Research and Management of Fishery Resources of the Northern Coast and the Carcinology Laboratory of the Federal Rural University of Pernambuco. The 189 identified specimens represented Lysiosquilla scabricauda (Lamarck, 1818) (n = 2), Parasquilla meridionalis Manning, 1916 (n = 1), Squilla empusa Say, 1818 (n = 6), and Squilla lijdingi Holthuis, 1959 (n = 180). Only three species were collected in each of the survey sectors, with L. scabricauda and S. lijdingi being captured in both sectors. Squilla lijdingi was dominant in both sectors, whereas the other species were considered to be rare. Squilla lijdingi was very frequent in the northern sector, although the other stomatopods were infrequent. In the southern sector, L. scabricauda was sporadic, S. empusa was frequent, and S. lijdingi was very frequent. A significant difference was observed in the number of specimens captured in both sectors. The Shannon index was 0.6144 bits.ind-1 for the northern sector and 0.2708 bits.ind-1 for the southern one, whereas equitability was 0.3876 in the North and 0.1708 in the South. The stomatopods were collected at depths between 32 and 109 m, and were captured primarily on gravelly bottoms in the northern sector, and on muddy substrates in the southern sector. Stomatopods were more abundant in the northern sector during the dry season from June to November, whereas they were more common in the South during rainy season, from December to May.

Diversity and structure of the stomatopod (Crustacea) community on the Amazon continental shelf

The present study aimed to characterize the biodiversity of the Stomatopoda species found off the coast of the northern Brazilian states of Amapá and Pará, within the region's Exclusive Economic Zone. Two distinct sectors were surveyed, to the north and to the south of Cape Norte. The specimens were collected during fishery surveys carried out between 1996 and 1998 by the Revizee Program, using bottom shrimp trawl nets. The specimens were identified at the Crustaceans Laboratory of the Center for Research and Management of Fishery Resources of the Northern Coast and the Carcinology Laboratory of the Federal Rural University of Pernambuco. The 189 identified specimens represented Lysiosquilla scabricauda (Lamarck, 1818) (n = 2), Parasquilla meridionalis Manning, 1916 (n = 1), Squilla empusa Say, 1818 (n = 6), and Squilla lijdingi Holthuis, 1959 (n = 180). Only three species were collected in each of the survey sectors, with L. scabricauda and S. lijdingi being captured in both sectors. Squilla lijdingi was dominant in both sectors, whereas the other species were considered to be rare. Squilla lijdingi was very frequent in the northern sector, although the other stomatopods were infrequent. In the southern sector, L. scabricauda was sporadic, S. empusa was frequent, and S. lijdingi was very frequent. A significant difference was observed in the number of specimens captured in both sectors. The Shannon index was 0.6144 bits.ind-1 for the northern sector and 0.2708 bits.ind-1 for the southern one, whereas equitability was 0.3876 in the North and 0.1708 in the South. The stomatopods were collected at depths between 32 and 109 m, and were captured primarily on gravelly bottoms in the northern sector, and on muddy substrates in the southern sector. Stomatopods were more abundant in the northern sector during the dry season from June to November, whereas they were more common in the South during rainy season, from December to May.(AU)

REPRODUCTIVE BEHAVIOR OF Dendrocephalus brasiliensis, Pesta 1921 (CRUSTACEAN: ANOSTRACA) / COMPORTAMENTO REPRODUTIVO DE Dendrocephalus brasiliensis, Pesta 1921 (CRUSTACEA: ANOSTRACA)

The reproductive behavior of fresh water Anostracan has not been massively studied by the carcinology specialized literature, regarding especially the Dendrocephalus brasiliensis Pesta, 1921, about which there are abundant studies only on the geographical distribution of that Anostracan. The objective of this research was to investigate the reproductive behavior of this Anostracan in different periods (dry and rainy). For this, mature individuals of both sexes were used. They were collected in four ponds of the Fish Farming Station of Paulo Afonso (FFSPA), by monthly capture in each pond, within the period from December 2004 to November 2005. The reproduction type was observed by placing some females in aquariums with males and placing the other ones individually, starting from the nauplii phase, where they stayed for 15 days (reproductive age). The individuals" sexual proportion was calculated by the relative frequencies of males and of females, every month, for the whole collection period. At 10 days cysts production is possible and the number of produced cysts is related to the size of the female. The ratio male:female in the studied period was of 1 male to 1.07 female. The proportion male:female was 51.75% female to 48.25% male along the year. The observation of the reproductive behavior showed the reproduction is sexed.KEYWORDS: crustacean; fresh water; reproduction; Thamn

O comportamento reprodutivo de anostráceos de água doce tem sido pouco divulgado na literatura especializada em carcinologia, especificamente em relação ao Dendrocephlaus brasiliensis Pesta, 1921, havendo apenas dados abundantes sobre a distribuição geográfica desse anostráceo dulciaquícola. O objetivo deste trabalho foi conhecer o comportamento reprodutivo desse Anostraca, em diferentes períodos (seco e chuvoso). Para isto, foram utilizados indivíduos maduros de ambos os sexos coletados em quatro viveiros da Estação de Piscicultura de Paulo Afonso (EPPA), por meio de captura mensal em cada viveiro, durante o período de dezembro de 2004 a novembro de 2005. O tipo de reprodução foi observado através da colocação em aquários, de algumas fêmeas juntas com machos e outras individualmente, a partir da fase de náuplios, onde permaneceram por 15 dias (idade reprodutiva). A proporção sexual dos indivíduos foi calculada através das frequências relativas de machos e de fêmeas, a cada mês, para todo o período de coleta. Aos 10 dias é possível produção de cistos e o número desses está relacionado ao tamanho da fêmea. A relação macho:fêmea no período de estudo foi de 1 macho para 1,07 fêmea. A proporção macho:fêmeas foi de 51,75% de fêmea para 48,25% de machos ao longo do ano. Foi observado, por meio do comportamento reprodutivo, tratar-se de reprodução sexuada.PALAVRAS-CHAVE: água doce; cr

REPRODUCTIVE BEHAVIOR OF Dendrocephalus brasiliensis, Pesta 1921 (CRUSTACEAN: ANOSTRACA) / COMPORTAMENTO REPRODUTIVO DE Dendrocephalus brasiliensis, Pesta 1921 (CRUSTACEA: ANOSTRACA)

The reproductive behavior of fresh water Anostracan has not been massively studied by the carcinology specialized literature, regarding especially the Dendrocephalus brasiliensis Pesta, 1921, about which there are abundant studies only on the geographical distribution of that Anostracan. The objective of this research was to investigate the reproductive behavior of this Anostracan in different periods (dry and rainy). For this, mature individuals of both sexes were used. They were collected in four ponds of the Fish Farming Station of Paulo Afonso (FFSPA), by monthly capture in each pond, within the period from December 2004 to November 2005. The reproduction type was observed by placing some females in aquariums with males and placing the other ones individually, starting from the nauplii phase, where they stayed for 15 days (reproductive age). The individuals" sexual proportion was calculated by the relative frequencies of males and of females, every month, for the whole collection period. At 10 days cysts production is possible and the number of produced cysts is related to the size of the female. The ratio male:female in the studied period was of 1 male to 1.07 female. The proportion male:female was 51.75% female to 48.25% male along the year. The observation of the reproductive behavior showed the reproduction is sexed.KEYWORDS: crustacean; fresh water; reproduction; Thamn

O comportamento reprodutivo de anostráceos de água doce tem sido pouco divulgado na literatura especializada em carcinologia, especificamente em relação ao Dendrocephlaus brasiliensis Pesta, 1921, havendo apenas dados abundantes sobre a distribuição geográfica desse anostráceo dulciaquícola. O objetivo deste trabalho foi conhecer o comportamento reprodutivo desse Anostraca, em diferentes períodos (seco e chuvoso). Para isto, foram utilizados indivíduos maduros de ambos os sexos coletados em quatro viveiros da Estação de Piscicultura de Paulo Afonso (EPPA), por meio de captura mensal em cada viveiro, durante o período de dezembro de 2004 a novembro de 2005. O tipo de reprodução foi observado através da colocação em aquários, de algumas fêmeas juntas com machos e outras individualmente, a partir da fase de náuplios, onde permaneceram por 15 dias (idade reprodutiva). A proporção sexual dos indivíduos foi calculada através das frequências relativas de machos e de fêmeas, a cada mês, para todo o período de coleta. Aos 10 dias é possível produção de cistos e o número desses está relacionado ao tamanho da fêmea. A relação macho:fêmea no período de estudo foi de 1 macho para 1,07 fêmea. A proporção macho:fêmeas foi de 51,75% de fêmea para 48,25% de machos ao longo do ano. Foi observado, por meio do comportamento reprodutivo, tratar-se de reprodução sexuada.PALAVRAS-CHAVE: água doce; cr