Changes in fish diets and food web mercury bioaccumulation induced by an invasive planktivorous fish.

The invasion, boom, collapse, and reestablishment of a population of the planktivorous threadfin shad in Clear Lake, California, USA, were documented over a 20-year period, as were the effects of changing shad populations on diet and mercury (Hg) bioaccumulation in nearshore fishes. Threadfin shad competitively displaced other planktivorous fish in the lake, such as inland silversides, young-of-year (YOY) largemouth bass, and YOY bluegill, by reducing zooplankton abundance. As a result, all three species shifted from a diet that was dominated by zooplankton to one that was almost entirely zoobenthos.

Mercury trophic transfer in a eutrophic lake: the importance of habitat-specific foraging.

Mercury (Hg) trophic transfer and bioaccumulation in fish from a mine-impacted, eutrophic lake were examined in relation to foraging habitat, trophic position, and size. Diet analysis indicated that there were clear ontogenetic shifts in foraging habitats and trophic position. Pelagic diet decreased and benthic diet increased with increasing fish length in bluegill, black crappie, inland silverside, and largemouth bass, whereas there was no shift for prickly sculpin or threadfin shad.

Spatiotemporal trends in fish mercury from a mine-dominated ecosystem: Clear Lake, California.

Clear Lake, California, USA, receives acid mine drainage and mercury (Hg) from the Sulphur Bank Mercury Mine, a U.S. Environmental Protection Agency (U.

Mine-derived mercury: effects on lower trophic species in Clear Lake, California.

Considerable ecological research on mercury (Hg) has focused on higher trophic level species (e.g., fishes and birds), but less on lower trophic species.

Natural variability in the seasonal occurrence and densities of adult populations of Ochlerotatus sierrensis.

This study examined the utility of Fay traps baited with carbon dioxide (Fay/CO2 traps) and ovitraps for monitoring adult Ochlerotatus sierrensis over time and space in the Coast Range of northern California. During a 3-year study in a dense oak woodland, Fay/CO2 traps collected adults from March to November at rates that were correlated with air temperature through peak activity periods ending in late June for males and late July for females. Variability in total annual rainfall did not explain the 3-fold difference in the numbers of females caught among years.