Contaminants can harm wildlife. However, measuring wildlife exposure to contaminants can be challenging due to accessibility of species and/or sampling tissue matrices needed to assess wildlife health risks. For example, in bats and other taxa that use roosts, collecting feces under colonies minimizes disturbance to species of conservation concern, but fecal contaminant concentrations may not directly correlate with tissue con...

Acoustic deterrents can reduce marine mammal interactions with fisheries and aquacultures, but they contribute to an increasing level of underwater noise. In Southern California, commercially produced explosive deterrents, commonly known as “seal bombs,” are used to protect fishing gear and catch from pinniped predation, which can cause extensive economic losses for the fishing community. Passive acoustic monitoring data colle...

Investigating intraspecific variation in acoustic signals can indicate the extent of isolation and divergence between populations and adaptations to local environments. Here we analyze the variation in killer whale high‐frequency (>17 kH z) whistles recorded off Norway, Iceland, and in the North Pacific. We used a combination of methods including multivariate comparisons of spectral and temporal parameters and categorization o...

The “dilution effect” concept in disease ecology offers the intriguing possibility that clever manipulation of less competent hosts could reduce disease prevalence in populations of more competent hosts. The basic concept is straightforward: host species vary in suitability (competence) for parasites, and disease transmission decreases when there are more incompetent hosts interacting with vectors or removing free‐living stage...

The pathological changes induced by an infection of Diphyllobothrium dendriticum (Nitzsch, 1824) plerocercoids in powan, Coregonus lavaretus (L.), from Loch Lomond, Scotland, were assessed using immunohistochemical and ultrastructural techniques. In a sample of 26 powan, the occurrence of encysted plerocercoids of D. dendriticum on the outer surface of the stomach was 38.5% ( n = 10) with the number of cysts ranging from 4 to...

The effect of osmotic shock was investigated mainly in the chloride cells (CCs) and rodlet cells (RCs) of gills, and RCs of intestine and kidney of the European sea bass Dicentrarchus labrax obtained from a farm in the northern Adriatic Sea. During the experiment, fish were abruptly transferred from sea water to a salinity of 15 (15 SW) or to fresh water (FW). Numeric variation and ultrastructural changes of both cell types we...

Immunohistochemical examination of the galaninergic and the diffuse endocrine systems of the alimentary canal of three catfish species, Ameiurus melas, Silurus glanis and Clarias gariepinus showed the presence of galanin‐like immunoreactive endocrine cells in the stomachs and the proximal intestines and a galanin‐like immunoreactivity within the enteric intramural neurons. The three species differed notably in the relative abu...

A histopathological and immunohistochemical study on the intestines of 45 specimens of farmed rainbow trout, Oncorhynchus mykiss (Walbaum), from Loch Awe, Scotland, revealed a number of cellular deviations in individuals naturally infected with the pseudophyllidean cestode Eubothrium crassum (Bloch, 1779). Twenty‐five individuals (55.5%) were infected with an average worm burden of 18.84 ± 4.06 (mean ± SE) cestodes per host (r...

Handling stress and exposure to the herbicide Stam® M‐4 (Propanil) were associated with an exponential depletion of the rodlet cells (RC) in the bulbus arteriosus of chub Leuciscus cephalus . Structural changes of the RC in herbicide‐exposed fish were encountered, including the occurrence of myeloid bodies in the cytoplasm of the RC of the intestine, various degrees of rodlet degeneration and high vacuolization in the cytoplas...

The histopathology, immunohistochemistry and ultrastructure of the alimentary canal of chub, Leuciscus cephalus (L.), from the River Brenta, naturally infected with the acanthocephalan Pomphorhynchus laevis Müller, 1776, was studied and described. Of 62 chub examined, 54 (87%) were infected with P. laevis ; the intensity of infection ranged from five to 130 parasites per host, and a density of 8 P. laevis per cm 2 was common....

In the bulbus arteriosus of goldfish Carassius auratus a subendothelial ‘reticular space’ was comprised of reticular‐like cells, neutrophils, medium‐sized granular leucocytes, phagocytes, endothelial cells and reticulo‐endothelial cells; herein, rodlet cells (RCs) accumulated and probably matured. Four classes of RCs were identified: (1) Those occurring in the reticular space and contacting reticular‐like cells; (2) those pres...