Parasitism and phagocytic function among sand lance Ammodytes hexapterus Pallas exposed to crude oil-laden sediments

Hematological parameters of Hoplias malabaricus (Characiformes: Erythrinidae) parasitized by Monogenea in lagoons in Pirassununga, Brazil

Hematology is an important pathological and diagnostic tool. This paper describes the hematological parameters of 76 specimens of Hoplias malabaricus infested with monogenean parasites, which were collected from two lagoons. The hematological parameters included: erythrocyte count (Er), microhematocrit (Hct), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). The blood parameters showed no significant changes associated with the infestation. Water temperature was found to be negatively correlated with MCV and Hct, with values of rs= -0.52, p<0.0001 and rs= -0.48, p<0.0001, respectively. The mean Relative Condition Factor was Kn=1.01, indicating good health conditions of the fish in these lagoons. No correlation was found between the monogenean infestation and the blood parameters, or between the environmental factors and the monogeneans.

The pink shrimp Farfantepenaeus duorarum, its symbionts and helminths as bioindicators of chemical pollution in Campeche Sound, Mexico

The pink shrimp Farfantepenaeus duorarum may acquire pollutants, helminths and symbionts from their environment. Statistical associations were studied between the symbionts and helminths of F. duorarum and pollutants in sediments, water and shrimps in Campeche Sound, Mexico. The study area spatially overlapped between offshore oil platforms and natural shrimp mating grounds. Spatial autocorrelation of data was controlled with spatial analysis using distance indices (SADIE) which identifies parasite or pollutant patches (high levels) and gaps (low levels), expressing them as clustering indices compared at each point to produce a measure of spatial association. Symbionts included the peritrich ciliates Epistylis sp. and Zoothamnium penaei and all symbionts were pooled. Helminths included Hysterothylacium sp., Opecoeloides fimbriatus, Prochristianella penaei and an unidentified cestode. Thirty-five pollutants were identified, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and heavy metals. The PAHs (2-3 ring) in water, unresolved complex mixture (UCM), Ni and V in sediments, and Zn, Cr and heptachlor in shrimps were significantly clustered. The remaining pollutants were randomly distributed in the study area. Juvenile shrimps acquired pesticides, PAHs (2-3 rings) and Zn, while adults acquired PAHs (4-5 rings), Cu and V. Results suggest natural PAH spillovers, and continental runoff of dichlorodiphenyltrichloroethane (DDT), PCBs and PAHs (2-3 ring). There were no significant associations between pollutants and helminths. However, there were significant negative associations of pesticides, UCM and PCBs with symbiont numbers after controlling shrimp size and spatial autocorrelation. Shrimps and their symbionts appear to be promising bioindicators of organic chemical pollution in Campeche Sound.

Marine parasites as pollution indicators: an update

Eight major reviews are cited to indicate a recent knowledge explosion on the use of marine parasites as potential indicators of pollution. A literature update is given for the period 1995–2001. An analysis of the publications cited is used to provide 10 refined criteria for selecting parasites as indicator/monitor species. Previously unpublished data on Diclidophora merlangi and Dictyocotyle coeliaca confirm their value as potential indicators of hydrocarbon pollution in the North Sea. An extensive knowledge of D. merlangi is summarised to emphasize its potential value as an indicator species and also to encourage studies on the health status and immune responses of its host when subjected to pollutant stressors and infection with this monogenean. A discussion focuses on publications which have reported significant recent advances in this area of research and also on accompanying issues, problems and controversies. These selected publications are used to suggest species, stages in the development of species and assemblages of species worthy of further more detailed investigations into their value as indicators/monitors of pollution. It is predicted that further good progress will be made when contaminants can be accurately identified, their precise effects on both host and parasite can be measured by histochemical and biological methods and the roles of contaminants and parasites in causing disease can be assessed separately. About 100 references are cited.