Observations on parasite fauna of centropomus undecimalis and C. parallelus (perciformes) bred in southern Brazil, and its possible influence on the welfare of fishes.

The metazoan parasite fauna of snooks, Centropomus parallelus and Centropomus undecimalis, cultured in southern Brazil and parasite?s influence on the relative condition factor (Kn), are investigated. Snooks were parasitized by two species of gill monogeneans belonging to Rhabdosynochus (Diplectanidae) genus and by one endoparasitic digenean species Acanthocollaritrema umbilicatum (Acanthocollaritrematidae). Centropomus parallelus and C. undecimalis showed similar prevalence rates of Rhabdosynochus spp., but greater mean intensity and abundance rates were found in C. parallelus. On the other hand, there was no significant difference on prevalence, mean intensity and abundance of A. umbilicatumfor both hosts. The mean abundance of Rhabdosynochusspp. decreased as the hosts´ length and weight increased. Since the most parasitized fish species, C. parallelus, had lower weight than expected (Kn<1.0), the fact suggested that gill monogeneans might alter fish welfare. Current analysis reports a new host and a new locality for A. umbilicatum

Underground railroads: citizen entitlements and unauthorized mobility in the antebellum period and today

In recent years, some scholars and prominent political figures have advocated the deepening of North American integration on roughly the European Union model, including the creation of new political institutions and the free movement of workers across borders. The construction of such a North American Union, if it included even a very thin trans-state citizenship regime, could represent the most significant expansion of individual entitlements in the region since citizenship was extended to former slaves in the United States. With such a possibility as its starting point, this article explores some striking parallels between the mass, legally prohibited movement across boundaries by fugitive slaves in the pre-Civil War period, and that by current unauthorized migrants to the United States. Both were, or are, met on their journeys by historically parallel groups of would-be helpers and hinderers. Their unauthorized movements in both periods serve as important signals of incomplete entitlements or institutional protections. Most crucially, moral arguments for extending fuller entitlements to both groups are shown here to be less distinct than may be prima facie evident, reinforcing the case for expanding and deepening the regional membership regime

Observations on parasite fauna of centropomus undecimalis and C. parallelus (perciformes) bred in southern Brazil, and its possible influence on the welfare of fishes.

The metazoan parasite fauna of snooks, Centropomus parallelus and Centropomus undecimalis, cultured in southern Brazil and parasite?s influence on the relative condition factor (Kn), are investigated. Snooks were parasitized by two species of gill monogeneans belonging to Rhabdosynochus (Diplectanidae) genus and by one endoparasitic digenean species Acanthocollaritrema umbilicatum (Acanthocollaritrematidae). Centropomus parallelus and C. undecimalis showed similar prevalence rates of Rhabdosynochus spp., but greater mean intensity and abundance rates were found in C. parallelus. On the other hand, there was no significant difference on prevalence, mean intensity and abundance of A. umbilicatumfor both hosts. The mean abundance of Rhabdosynochusspp. decreased as the hosts´ length and weight increased. Since the most parasitized fish species, C. parallelus, had lower weight than expected (Kn<1.0), the fact suggested that gill monogeneans might alter fish welfare. Current analysis reports a new host and a new locality for A. umbilicatum.201

Parasitos de Centropomus undecimalis e Centropomus parallelus (perciformes) cultivados em Santa Catarina (Brasil) e relação hospedeiro-parasito.

Os robalos são reconhecidos como espécies de grande potencial para a aquicultura, devido à boa taxa de crescimento, a qualidade da carne que é branca, delicada e com pouca gordura. A separação do filé é fácil, com alto rendimento e não apresenta espinhos. Seu valor de mercado está entre os mais elevados, considerando peixes marinhos e de água doce. No entanto, são peixes sensíveis à baixa qualidade ambiental podendo provocar estresse e doenças. As doenças parasitárias são fatores limitantes ao incremento da produção e produtividade, causando prejuízos econômicos significativos ao produtor, devido à elevada mortalidade. Portanto, é necessário identificar os parasitos causadores de infecções em robalos cultivados e avaliar as condições sanitárias, para então implantar e/ou melhorar medidas profiláticas. O presente estudo investigou a parasito fauna de Centropomus parallelus e Centropomus undecimalis cultivados, bem como a relação hospedeiro-parasito por meio de índices biométricos, fator de condição e índice hepatosomático. Tais parâmetros corporais são considerados indicadores do estado de saúde em populações de peixes cultivados e ambiente natural. Estudos sobre a ecologia de parasitos nos cultivos destes peixes são, dessa maneira, necessários para melhor compreender as relações parasito-hospedeiro. Entre novembro de 2011 e maio de 2012, 44 espécimes de C. parallelus e 20 de C. undecimalis provenientes da Fazenda de cultivo Yakult, Barra do Sul, SC foram submetidos à análise parasitológica. Os peixes estavam separados por espécie e distribuídos em 19 tanques rede, com água salobra e apresentavam cerca de 1 ano e meio de vida. Após anestesia com eugenol, cada peixe foi medido e pesado. Em seguida, os peixes foram sacrificados por comoção cerebral para análise do muco, brânquias e trato gastrointestinal, para coleta dos parasitos. O fígado de C. parallelus e C. undecimalis foi pesado (g) e usado para calcular o índice hepatosomático (IHS%). Os dados de peso (g) e comprimento total (cm) dos hospedeiros foram usados para calcular o fator de condição relativa (Kn). Nas brânquias de C. parallelus e C. undecimalis foram identificados Monogenea, Rhabdosynochus rhabdosynochus Mizelle e Blatz, 1941 e Rhabdosynochus hudsoni Kritsky, Boeger e Robaldo, 2001 (Diplectanidae) e no trato gastrointestinal digenéticos Acanthocollaritrema umbilicatum Travassos, Freitas e Bührheim, 1965 (Acanthocollaritrematidae), os quais mostraram dispersão agregada em ambos os hospedeiros. Para C. parallelus e C. undecimalis houve similar prevalência de Rhabdosynochus spp., mas ocorreu maior intensidade e abundância média em C. parallelus. Não foi encontrada diferença na prevalência, intensidade e abundância média de A. umbilicatum para ambos os hospedeiros. A abundância média de Rhabdosynochus spp. aumentou com o comprimento e peso de C. parallelus e C. undecimalis. O índice hepatosomático de C. parallelus diminuiu com a abundância de Rhabdosynochus spp. Em C. parallelus e C. undecimalis houve baixa diversidade de parasitos, uma vez que esses peixes foram parasitados somente por ectoparasitos Rhabdosynochus spp. e endoparasitos A. umbilicatum. No presente estudo, o robalo peva C. parallelus é considerado um novo hospedeiro e Santa Catarina uma nova localidade para A. umbilicatum, assim como o primeiro registro de R. rhabdosynochus e R. hudsoni em robalos cultivados no estado

Effect of water temperature and salinity in oviposition, hatching success and infestation of Aphanoblastella mastigatus (Monogenea, Dactylogyridae) on Rhamdia quelen

Abstract Several environmental parameters may influence biological processes of several aquatic invertebrates, such as the Monogenea. Current analysis investigates oviposition, hatching success and infestation of Aphanoblastella mastigatus, a parasite of the silver catfish Rhamdia quelen at different temperatures (~ 24 and 28 °C) and salinity (by adding sodium chloride to water, at concentrations 0, 5 and 9 g/L) in laboratory. There was no significant difference in oviposition rate and in A. mastigatus infestation success at 24 and 28 °C. On the other hand, the concentration 9 g/L of sodium chloride in the water impaired the parasite’s survival and the viability of the eggs. Results show that its usage is efficient as a possible prophylactic treatment. Eclosion rate of A. mastigatus’s eggs was significantly higher at 28 °C, although it was significantly less from 5 g/L. Two oviposition peaks (06h15 and 18h15) occurred during a 24-hour period, or rather, during the highest variations in luminosity. Further studies are recommended with greater temperature intervals and more intense experimental infestations to verify the effects of temperature in the life span and infestation success of A. mastigatus