PubMed · 4423148
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M S Watts. 1974. Editorial: WAMI.. https://pubmed.ncbi.nlm.nih.gov/4423148/
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The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction.
The dominant sources of the petrogenic hydrocarbon background in benthic sediments of Prince William Sound, AK (PWS), site of the 1989 Exxon-Valdez oil spill, are eroding Tertiary shales and residues of natural oil seepage. Mass balance considerations and statistical analyses of hydrocarbon fingerprints independently indicate that coal contributes generally less than 1% of the polycyclic aromatic hydrocarbons (PAH) and chemical biomarkers in this background. This is environmentally significant because of presumed differences in the bioavailability of PAH in coal, seep oil residues, and shales. Coal particles are present in PWS sediments, but their PAH and chemical biomarker contributions are overwhelmed by those of seep oil residues and organic particles from shales of low-to-high thermally maturity. In the late Tertiary or early Quaternary, the currently exposed and eroding shale formations were heated into the oil-generation window and, consequently, are now relatively rich in extractable PAH and chemical biomarkers. The exposed and eroding coals in the area, in contrast, experienced long hot burial and are now thermally overmature with respect to oil generation. The concentrations of thermally sensitive PAH and biomarker compounds in PWS sediments are not consistent with a mature coal origin but are consistent with the low-to-high maturity shales and seep oils in the area.
We examined post-spill trends (1989-1998) of marine bird populations in Prince William Sound (PWS) following the Exxon Valdez oil spill (EVOS) to evaluate recovery of injured taxa. Two criteria were employed. First, we examined population trends of injured taxa only in the oiled area of PWS using regression models. Second, we examined population trends of injured taxa in the oiled area relative to the unoiled area using homogeneity of the slopes tests. We considered a population recovering if there was a positive trend using either criteria. We considered a population not recovering if there was no trend using either criteria or a negative trend in the oiled area. A significant negative trend in the oiled area relative to the unoiled area was considered a continuing and increasing effect. Most taxa for which injury was previously demonstrated were not recovering and some taxa showed evidence of increasing effects nine years after the oil spill. Four taxa (loons Gavia spp, Harlequin Duck Histrionicus histrionicus, Bufflehead Bucephala spp, and North-western Crow Corvus caurinus) showed weak to very weak evidence of recovery. None of these taxa showed positive trends in both winter and summer. Nine taxa (grebes Podiceps spp, cormorants Phalacrocorax spp, Black Oystercatcher Haematopus bachmani, Mew Gull Larus canus, Glaucous-winged Gull Larus glaucescens, terns Sterna spp, murres Uria spp, Pigeon Guillemot Cepphus columba, and murrelets Brachyramphus spp) showed no evidence of recovery during summer or winter. Four taxa (scoters Melanitta spp, mergansers Mergus spp, goldeneyes Bucephala spp, and Black-legged Kittiwaka Rissa tridactyla) showed evidence of continuing, increasing effects. We showed evidence of slow recovery, lack of recovery, and divergent population trends in many taxa which utilize shoreline and nearshore habitats where oil is likely to persist. Potential lingering spill effects and natural variability appear to be acting in concert in delaying recovery of many PWS bird populations.