Benzotriazole UV-stabilizer exposure in ring-billed gulls from an urban, freshwater harbour in Lake Ontario, Canada: evaluating contaminant bioaccumulation and potential health impacts.

Plastic-associated contaminants, including benzotriazole UV-stabilizers (BZT-UVs), are receiving increased attention due to their environmental persistence, long-range transport, and potential to induce biological toxicity. However, little data is available regarding bioaccumulation and potential health impacts secondary to chronic BZT-UVs exposure in wildlife. We investigated the accumulation of 13 plastic-associated contaminants, including nine BZT-UVs, in 75 ring-billed gull (RBGU; Larus delawarensis) eggs collected in 2022 from the Hamilton Harbour in Lake Ontario, Canada.

Mercury in eastern coyotes from Nova Scotia, Canada: Effects of geography and trophic position.

Mercury (Hg) is a global environmental concern due to its wide distribution and myriad of deleterious effects on biota. We studied hepatic Hg in a widespread, top predator in the terrestrial ecosystem of Nova Scotia, Canada, the eastern coyote (Canis latrans), to determine recent concentrations, identify drivers of variation in Hg levels, and assess the utility of this species as a mercury biomonitor for this ecosystem. Coyotes feeding at higher trophic levels, and those in the south and east of the province, had higher Hg concentrations, but there was high variability within and among age-sex groupings.

Accumulation of benzotriazole UV-stabilizers in relation to ingested plastics and associated health metrics in Larus gulls feeding at a landfill in Atlantic Canada.

Benzotriazole UV-Stabilizers (BZT-UVs), compounds added to plastics to reduce ultraviolet degradation, are considered contaminants of emerging concern given their environmental persistence and documented toxicity in humans and animals. UV328 is a BZT-UV that has been recently listed to Annex A of the Stockholm Convention; therefore, understanding species exposure is critical information to fulfill international and domestic regulatory obligations. We evaluated hepatic accumulation of 12 plastic additives (including nine BZT-UVs) in Larus gulls in Atlantic Canada.

Plastic ingestion, accumulated heavy metals, and health metrics of four Larus gull species feeding at a coastal landfill in eastern Canada.

The objectives of this research were to assess ingested plastics and accumulated heavy metals in four urban gull species. Additionally, the relationships between ingested plastics and selected demographic and health metrics were assessed. Between 2020-2021 during the non-breeding seasons, 105 gulls (46 American herring gulls (HERG, Larus argentatus smithsonianus), 39 great black-backed gulls (GBBG, Larus marinus), 16 Iceland gulls (Larus glaucoides), 4 glaucous gulls (Larus hyperboreus)) were killed at a landfill in coastal Newfoundland and Labrador, Canada, as part of separate, permitted kill-to-scare operations related to aircraft safety.

Identifying sources of variation in parasite aggregation.

Aggregation of macroparasites among hosts is a near-universal pattern, and has important consequences for the stability of host-parasite associations and the impacts of disease. Identifying which potential drivers are contributing to levels of aggregation observed in parasite-host associations is challenging, particularly for observational studies. We apply beta regressions in a Bayesian framework to determine predictors of aggregation, quantified using Poulin's index of discrepancy (), for 13 species of parasites infecting Icelandic Rock Ptarmigan () collected over 12 years.

Metabarcoding prey DNA from fecal samples of adult dragonflies shows no predicted sex differences, and substantial inter-individual variation, in diets.

Sexes often differ in foraging and diet, which is associated with sex differences in size, trophic morphology, use of habitats, and/or life history tactics. Herein, strikingly similar diets were found for adult sexes of a dragonfly (), based on comparing 141 dietary taxa identified from the metabarcoding of mitochondrial DNA archived in feces. Arthropods in > 5% of samples included five species of dipterans, two hemipterans, two spider species and one parasitic mite.

Negative covariance between water mite and gregarine parasitism for adult dragonflies, Leucorrhinia intacta (Hagen): an age-related pattern?

Studies on parasite-mediated selection often focus on single parasite taxa infecting single species of hosts. However, host populations experience infections by multiple parasite taxa simultaneously; coinfection is expected to influence how host- and/or parasite-related factors affect host exposure and susceptibility to various parasites, and the resulting patterns of infection. We sampled adult dragonflies from a population of Leucorrhinia intacta (Hagen) in eastern Ontario, Canada.

Host species exploitation and discrimination by animal parasites.

Parasite species often show differential fitness on different host species. We developed an equation-based model to explore conditions favouring host species exploitation and discrimination. In our model, diploid infective stages randomly encountered hosts of two species; the parasite's relative fitness in exploiting each host species, and its ability to discriminate between them, was determined by the parasite's genotype at two independent diallelic loci.

Lesser snow goose helminths show recurring and positive parasite infection-diversity relations.

The patterns and mechanisms by which biological diversity is associated with parasite infection risk are important to study because of their potential implications for wildlife population's conservation and management. Almost all research in this area has focused on host species diversity and has neglected parasite diversity, despite evidence that parasites are important drivers of community structure and ecosystem processes. Here, we assessed whether presence or abundance of each of nine helminth species parasitizing lesser snow geese () was associated with indices of parasite diversity (i.

Explaining parasite aggregation: more than one parasite species at a time.

Studies generally have neglected parasite-centric views in explorations of whether the oft-seen patterns of parasite aggregation are adaptive. Using simulation models, we explored the effects of aggregation on coinfection with hetero- or conspecific parasite species characterised by different mean abundances. Increasing aggregation increased the probability of conspecific co-occurrence for parasites with low mean abundances, and increased median numbers of conspecifics for all species.

Aggregation of Infective Stages of Parasites as an Adaptation and Its Implications for the Study of Parasite-Host Interactions.

The causes and consequences of aggregation among conspecifics have received much attention. For infecting macroparasites, causes include variation among hosts in susceptibility and whether infective stages are aggregated in the environment. Here, we link these two phenomena and explore whether aggregation of infective stages in the environment is adaptive to parasites encountering host condition-linked defenses and what effect such aggregations have for parasite-host interactions.

Random parasite encounters coupled with condition-linked immunity of hosts generate parasite aggregation.

Parasite aggregation is viewed as a natural law in parasite-host ecology but is a paradox insofar as parasites should follow the Poisson distribution if hosts are encountered randomly. Much research has focused on whether parasite aggregation in or on hosts is explained by aggregation of infective parasite stages in the environment, or by heterogeneity within host samples in terms of host responses to infection (e.g.