Moderate pathogenic effect of Ligophorus uruguayense (Monogenoidea, Ancyrocephalidae) in juvenile mullet Mugil liza (Actinopterygii, Mugilidae) from Brazil

ABSTRACT Monogenoidea pathogenic activity can elicit various histological responses in fish. Species of Ligophorus are specific parasites of mullets, and its relationship with host fish may result in a moderate pathogenic action. In order to ascertain this relationship, estuarine mullets (Mugil liza) were collected in an estuary, reared in laboratory, for three weeks, and forwarded for histological and parasitological analyses. Ligophorus uruguayense (Monogenoidea) infestation in the gills of the mullets was identified. The severe infestation by only one species of Monogenoidea may result from the specificity of these parasites to mullets. Mullets submitted to histological analysis exhibited respiratory epithelium detachment; mild, moderate and severe hyperplasia of the respiratory epithelium; atrophy; and telangiectasia of the gills. This is the first study reporting that mullets highly infested by Monogenoidea can show mild (100%) to severe (20%) gill changes with a distinct frequency of occurrence. Because of the high prevalence of mild alterations observed, it is possible to accept that L. uruguayense is moderately pathogenic to M. liza, even during high prevalence and intensity of infestation, as a result of its specificity.

Parasite fauna of wild and cultured dusky-grouper Epinephelus marginatus (Lowe, 1834) from Ubatuba, southeastern Brazil / Fauna parasitária da garoupa selvagem e de cultivo Epinephelus marginatus (Lowe, 1834) em Ubatuba, sudeste do Brasil

This study aimed at identifying and quantifying the parasites of wild and cultured dusky grouper Epinephelus marginatus. During a year and thereby all four seasons, 20 wild and 20 cultured groupers were examined for the presence of parasites, except in the last season, in which 19 wild and 20 cultured fish were examined, totalling 159 groupers analysed from Ubatuba, southeastern Brazil. Prevalence, mean intensity of infection, mean abundance and mean relative dominance were calculated. Five species of parasites were identified in fish from both origins: Pseudorhabdosynochus beverleyburtonae (Monogenea), Neobenedenia melleni (Monogenea), Pseudempleurosoma sp. (Monogenea), Helicometrina nimia (Digenea) and larvae of Contracaecum sp. (Nematoda). The prevalence of ectoparasites, in most cases, was higher than endoparasites. The most abundant parasite was the monogenea Pseudorhabdosynochus beverleyburtonae in both wild and cultured fish, along all seasons. Neobenedenia melleni was observed in wild and cultured fish in all seasons, with a gradual increase in the number of parasites from the coldest to the hottest seasons, with the highest prevalence and mean intensity in the summer. Helicometrina nimia was found in all seasons in both wild and cultured fish, except for summer, where its presence was detected only in wild fish. Pseudempleurosoma sp. and larvae of Contracaecum sp. showed low prevalence occurring in wild and cultured fish in the autumn and spring, respectively. This study revealed high intensities of potentially pathogenic parasites that could favour disease outbreaks in culture conditions.

Este estudo teve como objetivo identificar e quantificar os parasitos da garoupa verdadeira Epinephelus marginatus selvagem e cultivada. Durante um ano, nas quatro estações, 20 garoupas selvagens e 20 cultivadas foram examinadas quanto à presença de parasitos, exceto na última estação, em que foram examinados 19 peixes selvagens e 20 cultivados, totalizando 159 peixes examinados em Ubatuba, Sudeste do Brasil. A prevalência, intensidade média de infecção, abundância média and dominância média relativa foram calculados. Cinco espécies de parasitos foram identificadas nos peixes de ambas as origens: Pseudorhabdosynochus beverleyburtonae (Monogenea), Neobenedenia melleni (Monogenea), Pseudempleurosoma sp. (Monogenea), Helicometrina nimia (Digenea) e larvas de Contracaecum sp. (Nematoda). A prevalência de ectoparasitos foi, na maioria das vezes, maior do que a de endoparasitos. O parasito mais abundante foi o monogenea Pseudorhabdosynochus beverleyburtonae em ambos os peixes selvagens e cultivados, durante todas as estações. Neobenedenia melleni foi observado e, peixes selvagens e cultivados em todas as estações, com aumento gradativo no número de parasitos das estações mais frias para as mais quentes, com as maiores prevalências e intensidades médias no verão. Helicometrina nimia foi encontrado em todas as estações em ambos os peixes selvagens e cultivados, exceto no verão, em que foi observada sua presença apenas em peixes selvagens. Pseudempleurosoma sp. e larvas de Contracaecum sp. apresentaram baixas prevalências, ocorrendo em peixes selvagens e cultivados no outono e na primavera, respectivamente. Este estudo revelou altas intensidades de parasitos potencialmente patogênicos que podem favorecer surtos de doenças em situações de cultivo.