Histopathology and autoecology of Didymocylindrus simplex (Digenea: Didymozoidae), parasite of Katsuwonus pelamis (Scombridae) in the Southwestern Atlantic Ocean, off South America

Pathological alterations and autoecology of Didymocylindrus simplex in Katsuwonus pelamis (Linnaeus, 1758) in the Southwestern Atlantic Ocean off of South America are presented. This is the first record of the species in the region; the specimens are described. The pathologic changes observed most often were infiltration of lymphocytes and slight fibrosis of the connective tissue surrounding the parasite. The typical aggregated distribution pattern was observed for Didymocylindrus simplex Ishii, 1935. Statistical analysis demonstrated no correlation between the abundance and prevalence of parasites with the total length of the host. The sex of the host does not influence the prevalence and intensity of infection.

Histopathology and autoecology of Didymocylindrus simplex (Digenea: Didymozoidae), parasite of Katsuwonus pelamis (Scombridae) in the Southwestern Atlantic Ocean, off South America

Pathological alterations and autoecology of Didymocylindrus simplex in Katsuwonus pelamis (Linnaeus, 1758) in the Southwestern Atlantic Ocean off of South America are presented. This is the first record of the species in the region; the specimens are described. The pathologic changes observed most often were infiltration of lymphocytes and slight fibrosis of the connective tissue surrounding the parasite. The typical aggregated distribution pattern was observed for Didymocylindrus simplex Ishii, 1935. Statistical analysis demonstrated no correlation between the abundance and prevalence of parasites with the total length of the host. The sex of the host does not influence the prevalence and intensity of infection.

Histopathology and autoecology of Didymocylindrus simplex (Digenea: Didymozoidae), parasite of Katsuwonus pelamis (Scombridae) in the Southwestern Atlantic Ocean, off South America

Pathological alterations and autoecology of Didymocylindrus simplex in Katsuwonus pelamis (Linnaeus, 1758) in the Southwestern Atlantic Ocean off of South America are presented. This is the first record of the species in the region; the specimens are described. The pathologic changes observed most often were infiltration of lymphocytes and slight fibrosis of the connective tissue surrounding the parasite. The typical aggregated distribution pattern was observed for Didymocylindrus simplex Ishii, 1935. Statistical analysis demonstrated no correlation between the abundance and prevalence of parasites with the total length of the host. The sex of the host does not influence the prevalence and intensity of infection.

Frequency of morphological alterations in the fish of Lake Guaíba and its application to environmental monitoring / Frequência de alterações morfológicas em peixes do Lago Guaíba e sua aplicação no monitoramento ambiental

This paper examined the association between the frequency of morphological alterations in fish and the physical and chemical parameters often used in monitoring water quality, with the aim of determining which places show most environmental degradation and which species are most affected. Fish samplings were standardized and carried out seasonally, using seine nets, in eleven locations in the catchment area of the Guaíba Lake. A total of 53,408 specimens were collected. Eight species were found to be constant in the samples and were therefore considered to be potential bioindicators. The highest frequency of morphological alterations was observed in the areas where the quality of water was the worst. Deformations of the opercular bones and of fin rays and spines were the most frequent alterations found. The repeated spatial pattern of the occurrence of deformations of fin rays and spines during two periods of study, points to this alteration as a good indicator of environmental quality.

Este artigo avaliou a associação entre a frequência de alterações morfológicas em peixes e os parâmetros físico-químicos frequentemente usados no monitoramento da qualidade da água, com o objetivo de determinar quais os locais que apresentam maior degradação ambiental e quais são as espécies mais afetadas. A amostragem de peixes foi padronizada e realizada sazonalmente com redes de arrasto do tipo picaré em onze pontos da bacia hidrográfica do Lago Guaíba. Foi coletado um total de 53 408 exemplares. Oito espécies foram consideradas constantes, o que as torna potencialmente bons indicadores. As maiores frequências de alterações morfológicas foram observadas nos pontos com pior qualidade da água. As anomalias mais frequentemente observadas foram deformação dos ossos do opérculo e deformação dos espinhos e raios das nadadeiras. A repetição dos padrões espaciais de ocorrência de deformação dos espinhos e raios das nadadeiras em dois períodos de estudo aponta este tipo de alteração como um bom indicador de qualidade ambiental.

Frequency of morphological alterations in the fish of Lake Guaíba and its application to environmental monitoring

This paper examined the association between the frequency of morphological alterations in fish and the physical and chemical parameters often used in monitoring water quality, with the aim of determining which places show most environmental degradation and which species are most affected. Fish samplings were standardized and carried out seasonally, using seine nets, in eleven locations in the catchment area of the Guaíba Lake. A total of 53,408 specimens were collected. Eight species were found to be constant in the samples and were therefore considered to be potential bioindicators. The highest frequency of morphological alterations was observed in the areas where the quality of water was the worst. Deformations of the opercular bones and of fin rays and spines were the most frequent alterations found. The repeated spatial pattern of the occurrence of deformations of fin rays and spines during two periods of study, points to this alteration as a good indicator of environmental quality.Key words: Guaíba. Environmental impact. Water quality.