No abstract

Biomarkers as lipid peroxidation, metallothionein and delta-aminolevulinic acid dehydratase were determined in Cathorops spixii to compare the biological responses of this fish from estuaries with distinct anthropogenic influence. Three areas were selected in two estuaries in accordance with the levels of contamination for the polluted (Santos/São Vicente) and with the hydrodynamic characteristics for the non-polluted (Cananéia) estuary. Water characteristics and mercury levels in C. spixii confirmed a high human influence in the polluted system. In general, the biomarkers showed differences between the estuaries, suggesting disturbances in the specific cell mechanisms due to the presence of multiple xenobiotics in the contaminated system. Therefore, these biomarkers are recommended to promote more accurate information about the exposure to pollutants. Additionally, the study of the effect of the multiple xenobiotics on resident species such as the benthic fish C. spixii can favor a better assessment of the environmental quality of these systems.

In the present study Cathorops spixii, was evaluated as a bioindicator fish for trace metal pollution. Concentrations of cobalt (Co), iron (Fe), selenium (Se) and zinc (Zn) were determined by Instrumental Neutron Activation Analysis in liver. Mercury (Hg) and methyl-mercury (MeHg) were analyzed by Cold Vapor Atomic Absorption Spectrometry in muscles and livers. High concentrations of Co, Fe, Se and Zn were observed in C. spixii from Santos Bay in comparison to fish collected in a non-polluted site in the same Brazilian coast. These trace metal concentrations were out of the permissible levels for human consumption. Although, Hg and MeHg levels were low, the C. spixii could still be used as an effective bioindicator to observe trace metal behaviors in the environment in function of the bioaccumulation process observed mainly by other analyzed trace metals. Thus, the use of this species is strongly recommended to monitor the effects and behavior of trace metal pollution in aquatic ecosystems in Brazil due to its bioaccumulation function.

Cyphocharax gilbert infested by Riggia paranensis shows parasitic castration. The prevalence of parasitism in C. gilbert varied among different environments, being higher in the middle rio Itabapoana. Fish were collected monthly using two cast nets (thrown 30 times during the day) and gillnets kept in the river during 12 hour, from sunset to sunrise, between September 1997 and August 2000. Infestation pattern was investigated on 1358 specimens. Most of them were infested (57.9%), with one or two parasites; the majority (62.9%) was collected during the rainy season (spring-summer). The parasite did not show preference for sex or size of hosts. A total of 91.5% of the 511 examined parasites had a body size that represented 10.1% to 20% of host standard length. The reproductive condition of 311 specimens of R. paranensis was analyzed checking the presence of oocytes in the ovarian and eggs or embryos in the marsupium. Nearly 73% of them were at reproductive phase, and had a body size that represented 5.1% to 20% of host standard length. The size of the immature parasites varied from 0.1% to 5% of the host size. The results suggest that R. paranensis may adopt a fast growth rate strategy and increase the investment in reproduction when they occupy most of the host's pericardial space.
Cyphocharax gilbert infestado por Riggia paranensis apresenta castração parasitária. A prevalência do parasito varia entre diferentes ambientes, sendo maior no trecho médio do rio Itabapoana. Os peixes foram coletados mensalmente neste rio usando duas tarrafas (lançadas por 30 vezes durante o dia) e redes de espera por 12 horas, do crepúsculo ao amanhecer, entre setembro de 1997 e agosto de 2000. O padrão de infestação foi investigado em 1358 peixes. Peixes infestados apresentaram um ou dois parasitos, representando 57,9% da população e a maioria deles (62,9%) foi coletada no período de maior precipitação (primavera-verão). O parasito não apresentou preferência por sexo ou tamanho do hospedeiro. No total, 91,5% de 511 parasitos examinados apresentaram um tamanho corpóreo que representou de 10,1% a 20% do comprimento padrão do hospedeiro. A condição reprodutiva em 311 espécimes R. paranensis foi analisada através da presença de oócitos no ovário e ovos ou embriões no marsúpio, sendo que cerca de 73% estavam em fase de reprodução, apresentando um tamanho corporal que variou entre 5,1% a 20% do comprimento padrão do hospedeiro. O tamanho dos parasitos imaturos variou de 0,1% a 5% do tamanho do hospedeiro. Os resultados sugerem que R. paranensis pode adotar uma estratégia de rápido crescimento e deve aumentar o investimento em reprodução quando ocupa grande parte do espaço disponível na cavidade pericardial do hospedeiro