Description of the egg capsule of Atlantoraja castelnaui (Elasmobranchii, Rajidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Length-weight relationships, condition and population structure of the genus Atlantoraja (Elasmobranchii, Rajidae, Arhynchobatinae) in Southeastern Brazilian waters, SW Atlantic Ocean

During the present study, 107 specimens of Atlantoraja castelnaui, 188 of A. platana, and 770 of A. cyclophora, were obtained by commercial vessels operating in Southeastern Brazil from March 2005 to April 2006. Males of A. castelnaui ranged from 17.9-111.0 cm and females from 17.4-116.0 cm total length. Males of A. platana ranged from 13.1-70.0 cm and females from 12.5-76.0 cm total length. Males of A. cyclophora ranged from 13.3-58.5 cm and females from 11.5-68.0 cm total length. Length-weight curves were sexually dimorphic in the three species. The analysis of the angular coefficient (b) demonstrated that growth (in weight) in relation to length was allometric (b>3) in males of A. castelnaui and A. platana, while isometric (b = 3) in females of these species. Conversely, growth of A. cyclphora was isometric in males, while in females it was allometric (b>3). The condition factor varied significantly throughout the year only in females of A. castelnaui.

Reproductive biology of Atlantoraja cyclophora (Regan 1903) (Elasmobranchii : Rajidae) off southern Brazil

A total of 459 (245 females, 214 males) Atlantoraja cyclophora was captured by bottom trawl off the coast of Rio Grande do Sul between 30 degrees 40'S and 34 degrees 30'S during surveys conducted in winter 2001 and summer/autumn 2002 at depths of 100-300 M. Total length at maturity was 52.8 cm for females and 48.5 cm for males. Symmetry and functional parity of the gonads were observed in both sexes, but there was no significant temporal variation in either sex for any of the reproductive parameters studied. Ovulation and egg-deposition were similarly intensive in both seasons. In adult females, there was an ovarian resting period at an individual level, though it was not synchronized at a population level. Distribution of egg-bearing females was not related to depth or species' range. (c) 2005 International Council for the Exploration of the Sea, Published by Elsevier Ltd. All rights reserved.

Size at maturity of Atlantoraja platana (Gunther, 1880) (Chondrichthyes : Rajidae : Arhynchobatinae) in the south-west Atlantic Ocean

The sexual development of Atlantoraja platana from the south-west Atlantic Ocean was analysed. According to the reproductive variables considered for both sexes, males were found to mature at 620 mm and females at 715 mm total length. (c) 2008 The Authors Journal compilation (c) 2008 The Fisheries Society of the British Isles.

Sexual development and reproductive cycle of the Eyespot skate Atlantoraja cyclophora (Regan, 1903) (Chondrichthyes: Rajidae: Arhynchobatinae), in southeastern Brazil

Specimens o/Atlantoraja cyclophora were collected monthly from commercial fishing landings at Guarujá, São Paulo State, Brazil, from March 2005 to April 2006 at depths between 10 and 146 m. Males ranged from 13.3 to 58.5 cm TL (n = 396). Both the smallest mature male and the largest immature male were 47.0 cm long. Males' size-at-50% maturity was calculated to be 46.3 cm. Females ranged from 11.5 to 68.0 cm (n = 401). The smallest mature and the largest immature female were 51.6 and 53.0 cm long respectively. For the females, size-at-50% maturity was calculated to be 53.2 cm. In the males the hepatosomatic andgonadosomatic indices varied between 0.48 (August) and 3.54 (November) and between 0.15 (November) and 1.45 (June) respectively, with no significant variation for the fourteen-month period. In the females the hepatosomatic and gonadosomatic indices varied from 1.55 and 6.30 3.54 (both for April 2006) and from 0.08 (December) to 4.41 (October) respectively, with no significant difference among months. Egg-bearing females were found in all months with proportions varying from 0.03 (March) to 0.67 (April). Both males and females undergo an annual cycle, with slight seasonal variations in reproductive activity and a peak in the proportion of egg bearing females between April and July.

Diel variation in mangrove fish abundances and trophic guilds of northeastern Australian estuaries with a proposed trophodynamic model

Diel activity patterns of tropical fish assemblages in turbid, mangrove-dominated estuaries remain largely undocumented, leading to uncertainty about ecological processes in these systems. To capture active fishes by day and night, gill nets were set perpendicular to mangrove shorelines, in six northeastern Australian estuaries during 13 bimonthly trips. Fish were sampled with eight large mesh (102-151 mm) nets, set for 6 hrs (1500-2100), and checked hourly (1146 day, 635 dusk, 872 night checks). Four smaller mesh (19-51 mm) nets were also set for 1 hr before and after sunset (77 day, 78 night checks). Of 157 total species, 22 were netted exclusively before sunset and 47 exclusively after sunset. All of the top 26 species were present both day and night, but of these, 46% were primarily nocturnal (diel index > 0.65). An average of 77.2 fish hr−1 were netted by day vs 171.4 by night. Within the 400 km coastal region, assemblages differed between two northern wave-dominated (WD) estuaries and four southern tide-dominated ('I'D) estuaries. In all six estuaries Lates calcarifer (Bloch, 1790) dominated night assemblages. In 'I'D estuaries, night assemblages were also dominated by Thryssa hamiltoni Gray, 1835 and Eleutheronema tetradactylum (Shaw, 1804); while in WD estuaries Herklotsichthys castelnaui (Ogilby, 1897), Leiognathus equulus (Forsskål, 1775), and Megalops cyprinoids (Broussonet, 1782) were dominant at night. Nocturnal species included planktivores and carnivores, while daytime assemblages were dominated by detritivores (Mugillidae). Higher night catch rates are attributed to increased activity by mobile fishes moving from mangrove to adjacent habitats to forage, especially immediately post-sunset. Although day-night diets and forage resources have yet to be compared in mangrove systems, previously unrecognized trophic relationships involving variation in diel activity among important fishery species (Centropomidae, polynemidae, Carangidae) and their prey may be key ecological processes in these tropical mangrove estuaries. A proposed hypothesis explaining diel variation in mangrove fish assemblages of tropical estuaries is presented through a conceptual model.

Hábitos alimentares e análise de sobreposição trófica de elasmobrânquios no litoral sul do Rio de Janeiro, Brasil

O presente trabalho analisou o conteúdo estomacal de cinco espécies de elasmobrânquios, sendo 9 estômagos de Psammobatis rutrum, 83 de Psammobatis extenta, 59 de Atlantoraja cyclophora, 112 de Rioraja agassizi e 43 de Rhizoprionodon lalandii, com o objetivo de obter informações sobre os hábitos alimentares dessas espécies, além de verificar a formação de guildas tróficas entre as espécies estudadas. As coletas ocorreram entre janeiro de 2006 e agosto de 2007, no litoral sul do Rio de Janeiro, ao largo da Ilha Grande. Os itens alimentares encontrados foram analisados quanto a Frequência de Ocorrência, Peso Percentual e Índice Alimentar, sendo a dieta de cada espécie avaliada considerando toda amostra, de acordo com o sexo dos indivíduos, estádios de maturidade e épocas do ano. Para investigar a similaridade entre as dietas e verificar a formação de guildas tróficas foi realizada uma Análise de Escalonamento Multidimensional (MDS). As dietas de Psammobatis rutrum e Psammobatis extenta foram consideradas carcino-bentófagas, com grande importância de camarões. O principal item para Atlantoraja cyclophora foi o siri Portunus spinicarpus, sendo a dieta considerada principalmente carcino-bentófaga, mas também com grande importância de teleósteos. Em Rioraja agassizi, a dieta foi considerada principalmente carcino-bentófaga, mas também com forte influência ictiófaga. Já o comportamento alimentar de Rhizoprionodon lalandii foi considerado ictio-bentófago. A dieta entre os sexos apresentou uma alta sobreposição em P. extenta, A. cyclophora e R. lalandii, mas para R. agassizi essa sobreposição foi considerada baixa. Entre os estádios de maturidade a sobreposição foi pequena para P. extenta e R. agassizi, entretanto para A. cyclophora e R. lalandii essa sobreposição foi elevada. Os exemplares maiores, aparentemente apresentaram preferência a se alimentarem de peixes, enquanto que predadores de menor porte se restringem aos invertebrados, basicamente crustáceos. Para todas as espécies foram identificadas alterações sazonais na importância dos itens alimentares, que pode ser explicado pelas oscilações naturais na composição e abundancia das presas potenciais em consequência das variações das massas de água na plataforma continental do sul fluminense. Os resultados indicaram a formação de 2 guildas, sendo a guilda 1 composta por P. rutrum e P extenta e com uma dieta principalmente de crustáceos (camarões) e a guilda 2 composta por A. cyclophora, R. agassizi e R. lalandii apresentando uma alimentação em Crustáceos e em Teleósteos.

Annelida, Hirudinida, Stibarobdella moorei (Oka, 1910): new distribution and host records.

The present report is the northernmost capture of the piscicolid leech Stibarobdella moorei in the western South Atlantic Ocean. This is also the first time S. moorei is found associated to a batoid fish in the Brazilian coast, the eyespot skate Atlantoraja cyclophora. Stibarobdella moorei was found fixed in the dorsal side of a male eyespot skate, caught by bottom trawl around of the São Paulo coast, southeastern Brazil. A brief description of the morphology of the parasite and a discussion on the taxonomic status of the S. moorei are presented.

Descrição da fauna parasitária de raias e tubarões marinhos (Elasmobranchii), fauna acompanhante da pesca comercial no litoral Sul e Sudeste do Brasil

Pós-graduação em Medicina Veterinária - FCAV

Species of Lecithocladium Luhe, 1901 (Digenea, Hemiuridae) from Australian marine fishes, with a description of a new species from various hosts off eastern Australia

Lecithocladium moretonense sp. nov. is described from Monodactylus argenteus (type-host), Abudefduf sordidus, A. whitleyi, Herklotsichthys castelnaui, Lutjanus russelli, Platycephalus indicus, Rhabdosargus sarba, Siganus nebulosus and Scorpis lineolata from Moreton Bay, southern Queensland, and Acanthopagrus australis from off northern New South Wales. It differs from most Lecithocladium species in having a subglobular oral sucker and pharynx. Other distinguishing features are the thin-walled recurved seminal vesicle and the pars prostatica coiling over the seminal vesicle to the level of the anterior testis. Lecithocladium megalaspis Yamaguti, 1953 from Alepes apercna, Moreton Bay and L. angustiovum Yamaguti, 1953 from Scomber australasicus, Fremantle, Western Australia, are also reported, illustrated and measured.

Temporal variation in habitat use by nekton in a subtropical estuarine system

Utilisation by fish of different estuarine habitats is known to vary at many different temporal scales, however no study to date has examined how utilisation varies at all the relevant times scales simultaneously. Here, we compare the utilisation by fish of sandy, intertidal foreshore habitats in a subtropical estuary at four temporal scales: between major spawning periods (spring/ summer and winter), among months within spawning periods, between the full and new moon each month, and between night and day within those lunar phases. Comparisons of assemblage composition, abundance of individuals and of fish in seven different,ecological guilds' were used to identify the temporal scales at which fish varied their use of unvegetated sandy habitats in the lower Noosa Estuary, Queensland, Australia. Fish assemblages were sampled with a seine net at three different regions. The most numerically dominant species caught were southern herring (Herklotsichthys castelnaui: Clupeidae), sand whiting (Sillago ciliata: Sillaginidae), weeping toadfish (Torquigener pleurogramma: Tetraodomidae), and silver biddy (Gerres subfasciatus: Gerreidae). Considerable variation at a range of temporal scales from short term (day versus night) to longer term (spawning periods) was detected for all but one of the variables examined. The clearest patterns were observed for diurnal effects, where generally abundance was greater at night than during the day. There were also strong lunar effects, although there were no consistent patterns between full moon and new moon periods. Significant differences among months within spawning periods were more common than differences between the actual spawning periods. The results clearly indicate that utilisation of sandy, unvegetated estuarine habitats is very dynamic and highly variable in space and time. (c) 2006 Elsevier B.V. All rights reserved.