An experimental study was carried out to investigate direct and direct plus trophic contamination routes of the crayfish Astacus astacus by inorganic mercury (Hg(II)) or methylmercury (MeHg). Direct exposure was based on low contamination conditions, 300 and 30 ng/L in the dissolved phase, respectively, during 30 d at 20 degrees C. Trophic exposure was based on daily consumption of the Asiatic ...

Sexual differences in parental investment, predation pressure, and foraging efforts are common in nature and affect the trophic flow in food webs. Specifically, the sexual differences in predator and prey behavior change in trophic inflow and outflow, respectively, while those in parental investment alter the reproductive allocation of acquired resources in the population. Consequently, these f...

Characterizing relationships between individual body size and trophic niche position is essential for understanding how population and food-web dynamics are mediated by size-dependent trophic interactions. However, whether (and how) intraspecific size-trophic relationships (i.e., trophic ontogeny pattern at the population level) vary with time remains poorly understood. Using archival specimens...

The distribution of current-use pesticides (CUPs) in seawater and their trophodynamics were investigated in 3 Canadian Arctic marine food chains. The greatest ranges of dissolved-phase concentrations in seawater for each CUP were endosulfan sulfate (less than method detection limit (MDL) to 19 pg L(-1) ) > dacthal (0.76-15 pg L(-1) ) > chlorpyrifos (less than MDL to 8.1 pg L(-1) ) > pentachloro...

Stable isotopes of carbon (delta13C) and nitrogen (delta15N) were used to describe sources of energy and trophic position for adult Leporinus friderici in the area of the Corumbá Reservoir, Brazil. Samples were collected from April 1999 to March 2000. Spatial variations were not identified in the isotopic composition. The maximum and minimum contribution of C4 plants calculated integrating the ...

It is a common problem in ecosystem studies that information about predation on fish larvae is extremely sparse. There is little information about agents of mortality. This is likely to be because fish larvae are digested very rapidly in a predator’s stomach. This study describes controlled experiments designed to evaluate the potential role of small low-trophic level fishes as predators on pel...

Ecologists have hypothesized that the exponent of species-area power functions (z value) should increase with trophic level. The main explanation for this pattern has been that specialist predators require prior colonization of a patch by their prey, resulting in a compounding of the effects of area up trophic levels. We propose two novel explanations, neither of which assumes trophic coupling ...

There is increasing recognition of the importance of dietary pathways in determining metal body burdens in marine organisms. With a simple kinetic model that requires information about the ingestion rate of an animal and the assimilation efficiency (AE) and efflux rate constant (ke) of a metal following dietary exposure, it is possible to quantitatively predict the trophic transfer and biomagni...

Preferential biomagnification of 14 dioxin-like polychlorinated biphenyls (PCBs) was determined in lower-trophic-level organisms of the Lake Michigan, USA, food web. Bioaccumulation of these coplanar, aryl hydrocarbon hydroxylase (AHH)-inducing PCB congeners and total PCBs in phytoplankton, zooplankton, Mysis relicta, and Diporeia sp. were studied for two locations in Lake Michigan over time. T...

Using bottom-trawl survey data to examine fishery resources in the Beibu Gulf, South China Sea, changes stock density, dominant species composition, mean trophic level, and fishing-in-balance index were comprehensively analyzed. The results show that density of declined gulf from 1961 2017. composition trawl surveys Gulf changed greatly 1961–1962 2016–2017 showed a shift bottom pelagic high-tro...