Investigating the potential uptake of microplastic-derived carbon into a boreal lake food web using carbon-13 labelled plastic

A study on the levels of radioactivity in fish samples from the experimental lakes area in Ontario, Canada

Aquatic, amphibious, and terrestrial organisms in or around a pond that was contaminated by e-waste were collected and persistent halogenated organic pollutants (HOPs) for these species were analyzed. Based on the stable isotope and dietary composition, the aquatic and terrestrial food webs and several insect-dominated food chains including insects – toads, insects – lizards, and insects – birds were constructed. Biomagnification factors (BMFs) for insect-dominated food chains and trophic magnification factors (TMFs) in aquatic and terrestrial food webs were calculated. The BMFs of HOPs (except DBDPE) in insect – bird food chains were significantly higher than those in insect – toad and insect – lizard food chains, indicating that HOPs accumulated more easily in homeotherms than in poikilotherms. Trophic magnification was present for most of the PCB congeners in both aquatic and terrestrial food webs. Differences between the trophic transfer of halogenated flame retardant in terrestrial and aquatic food webs were observed, with trophic magnification in the terrestrial food web but trophic dilution in the aquatic food web for most of chemicals (except for lower brominated PBDE congeners). Meanwhile, the contour plots of TMFs across combinations of log KOW and log KOA for terrestrial food web were distinct from those for aquatic food web. These results indicate that the biomagnification mechanisms of HOPs in aquatic food webs are different from those in terrestrial food webs, and further suggest that the bioaccumulation of contaminants in terrestrial ecosystems cannot be directly deduced from aquatic ecosystems.

Bioaccumulation and trophic transfer of antibiotics in the aquatic and terrestrial food webs of the Yellow River Delta

Effects of selenium on benthic macroinvertebrates and fathead minnow (Pimephales promelas) in a boreal lake ecosystem

Trophic transfer of methylmercury and brominated flame retardants in adjacent riparian and aquatic food webs: 13C indicates biotransport of contaminants through food webs

Wildfire in the boreal forests at the Experimental Lakes Area in Ontario caused significant losses of nitrogen and phosphorus in streams. Both watershed type and fire intensity appear to determine the extent of losses. The Northeast wetland basin lost more N and P, especially TDN, TDP, TN, and TP, than did terrestrial basins, although nitrate losses were higher from terrestrial basins. Losses of nutrients after the second fire generally were not as high as after the first fire. In the East basin, which burned twice with a high fire intensity, stream concentrations of NO3−, TDN, and TN were elevated for 6 yr between the fires and remained elevated for 9 yr after the second fire In contrast, the Northwest basin burned with a lower intensity and had no significant increase in annual concentrations of P or most forms of N in the first 3 yr after the fire; only NCV concentrations increased during this period. Despite the increases in export after wildfire, net retention of TN and TP over the 18-yr period was high. In the Northeast, East, and Northwest basins, retention of TN averaged 77, 80, and 87% compared with TP retention of 51, 67, and 84%.

Viruses that infect phytoplankton are an important component of aquatic ecosystems, yet in lakes they remain largely unstudied. In order to investigate viruses (Phycodnaviridae) infecting eukaryotic phytoplankton in lakes and to estimate the number of potential host species, samples were collected from four lakes at the Experimental Lakes Area in Ontario, Canada, during the ice-free period (mid-May to mid-October) of 2004. From each lake, Phycodnaviridae DNA polymerase (pol) gene fragments were amplified using algal-virus-specific primers and separated by denaturing gradient gel electrophoresis; 20 bands were extracted from the gels and sequenced. Phylogenetic analysis indicated that freshwater environmental phycodnavirus sequences belong to distinct phylogenetic groups. An analysis of the genetic distances "within" and "between" monophyletic groups of phycodnavirus isolates indicated that DNA pol sequences that differed by more than 7% at the inferred amino acid level were from viruses that infect different host species. Application of this threshold to phylogenies of environmental sequences indicated that the DNA pol sequences from these lakes came from viruses that infect at least nine different phytoplankton species. A multivariate statistical analysis suggested that potential freshwater hosts included Mallomonas sp., Monoraphidium sp., and Cyclotella sp. This approach should help to unravel the relationships between viruses in the environment and the phytoplankton hosts they infect.

Sources of atmospheric metal(loid) pollution recorded in Thompson Manitoba lake sediment cores within the Canadian boreal biome

Leeches are widespread, found in many freshwater habitats, and have diverse dietary habits. Despite their close phylogenetic relationships to Mollusca, a phylum with species affected by exogenous estrogens, it is unclear whether Hirudinea may also be impacted. A whole-lake experiment was done at the Experimental Lakes Area in Ontario, Canada, to assess whether 17α-ethynylestradiol (EE2) affected fishes and other species. Herein, we examined whether EE2 impacted leech community composition, species abundance, growth rates, gonad size, and cocoon production, when compared with reference lakes using a before-after-control-impact design. Each month baited leech traps were set overnight in the littoral zone at 10 sites around experimental Lake 260 and 2 reference lakes, and individuals were identified, weighed, and measured. Male and female organs of common species Haemopis marmorata were measured. Across all lakes, 9 species representing 3 families were collected. There were no apparent effects of EE2 on numbers, species richness, or community composition; however, condition in 1 of 5 species increased significantly after EE2 exposures. Total gonadosomatic index (GSI) and the GSI for all male or all female organs combined for H. marmorata were not affected by EE2 additions. However, some individual reproductive organs including relative sperm sac length (+), relative epididymis weight (-), relative vaginal bulb length (+), and relative ovisac + albumen gland length (+) changed after EE2 additions. Finally, whereas overall cocoon production was similar, it occurred earlier in the EE2-amended lake. In summary, few individual through community measures of leeches responded to low ng/L concentrations of EE2, suggesting that Hirudinea are less sensitive to this endocrine disruptor than other invertebrates and vertebrates. Environ Toxicol Chem 2020;39:1608-1619. © 2020 SETAC.

Both terrestrial and aquatic food webs are characterized by similar key parameters: connectance, robustness, and linkage. Ecosystems vary in basic structures and by processes that govern their dynamics and complexity. A study of complexity, connectance and link density in terrestrial and aquatic food webs, was conducted. We used 49 food webs apportioned in 23 terrestrials, 15 lacustrine and 11 rivers. The results revealed that aquatic food webs presented a difference in superiority of average connectance and link density, (p ~ 0.05), depicting an absence of differences in means. A regression test revealed that connectance and link density are inversely correlated in terrestrial food webs and contrary in other habitats, which was the same case for connectance and the average length of chain. We assume that connectance should be positively correlated with other parameters (fluxes and interaction strengths) in terrestrial habitat as its variations were not explained by link density or the average length of chain. This study revealed a higher estimate of connectance in aquatic habitats compared to their terrestrial counterparts. Aquatic habitats are potentially characterized by high values of parameters related to the connection (interactions quality, organisms' growth, and food web size) while terrestrial ones are more branded by features depicting constancy (productivity, complexity, and diversity).

Distinct biomagnification of chlorinated persistent organic pollutants in adjacent aquatic and terrestrial food webs

Factors Driving Temporal and Spatial Variation in Aquatic Floodplain Food Webs

Assessment of the impact of dams on aquatic food webs using stable isotopes: Current progress and future challenges

Preface.- Introduction.- Algal Lipids and Effect of the Environment on their Biochemistry.- Formation and transfer of fatty acids in aquatic microbial food webs - role of heterotrophic protists.- Ecological significance of sterols in aquatic food webs.- Fatty acids and oxylipins as semiochemicals.- Integrating lipids and contaminants in aquatic ecology and ecotoxicology.- Crustacean zooplankton fatty acid composition.- Fatty acid ratios in freshwater fish, zooplankton and zoobenthos - are there specific optima?- Preliminary estimates of the export of omega-3 highly unsaturated fatty acids (EPA+DHA) from aquatic to terrestrial ecosystems.- Biosynthesis of polyunsaturated fatty acids in aquatic ecosystems: general pathways and new directions.- Health and condition in fish: the influence of lipids on membrane competency and immune response.- Lipids in marine copepods: latitudinal characteristics and perspective to global warming.- Lipids in marine copepods: latitudinal characteristics and perspective to global warming.- Tracing aquatic food webs using fatty acids: from qualitative indicators to quantitative determination.- Essential fatty acids in aquatic food webs.- Human life: caught in the food web.

Habitat decoupling via saltmarsh creek geomorphology alters connection between spatially-coupled food webs