Ronald A. Heintz

Impacts to Pink Salmon Following the Exxon Valdez Oil Spill: Persistence, Toxicity, Sensitivity, and Controversy

Injury to a species resulting from long-term exposure to low concentrations of pollutants is seldom noted or even tested. One of the products of the Exxon Valdez oil spill was the first report of damage to eggs and larvae of pink salmon (Oncorhynchus gorbuscha) following long-term exposure to low concentrations of weathered crude oil. These life stages were previously thought to be highly resistant to injury from oil. Growth rate among migrating fry was depressed, and the population was reduced via size-dependent mortality. Elevated egg mortality in oiled streams continued for at least 4 years after the spill. Laboratory tests verified that embryos are sensitive to long-term exposure to weathered oil in the low parts per billion range. These results are compared with those of studies conducted by investigators funded by Exxon Corporation and, where controversy exists, we attempt to reconcile the studies. These findings are important to the pink salmon fisheries of Prince William Sound (PWS) and are also broadly applicable to toxicity and impact from nonpoint source pollution of urban estuaries.

Recovery of Pink Salmon Spawning Areas after the Exxon Valdez Oil Spill

Abstract Up to 70% of wild pink salmon Oncorhynchus gorbuscha in Prince William Sound, Alaska, spawn in intertidal stream areas, many of which were contaminated by the 1989 Exxon Valdez oil spill. To assess recovery of salmon habitat after the spill, we analyzed sediment samples from stream deltas throughout Prince William Sound from 1989 to 1991 and 1995. In 1989, petroleum hydrocarbon concentration at 172 stream deltas (1–8 samples each) was bimodally distributed: 85 deltas had no detectable petroleum hydrocarbons (detection limit, 2 μg/g), whereas 87 deltas had a concentration of 2–90,000 μg/g. In 1995, petroleum hydrocarbons were still detected at eight of nine oiled streams that we resampled, with mean concentration up to 242 μg/g. The polynuclear aromatic hydrocarbon (PAH) fraction was also analyzed in 1995 to determine its origin, state of weathering, and toxic potential of the residual oil. The PAH fraction consisted mostly of the more toxic compounds with high molecular weight (e.g., phenanthrene...

Return of warm conditions in the southeastern Bering Sea: Physics to fluorescence

From 2007 to 2013, the southeastern Bering Sea was dominated by extensive sea ice and below-average ocean temperatures. In 2014 there was a shift to reduced sea ice on the southern shelf and above-average ocean temperatures. These conditions continued in 2015 and 2016. During these three years, the spring bloom at mooring site M4 (57.9°N, 168.9°W) occurred primarily in May, which is typical of years without sea ice. At mooring site M2 (56.9°N, 164.1°W) the spring bloom occurred earlier especially in 2016. Higher chlorophyll fluorescence was observed at M4 than at M2. In addition, these three warm years continued the pattern near St. Matthew Island of high concentrations (>1 μM) of nitrite occurring during summer in warm years. Historically, the dominant parameters controlling sea-ice extent are winds and air temperature, with the persistence of frigid, northerly winds in winter and spring resulting in extensive ice. After mid-March 2014 and 2016 there were no cold northerly or northeasterly winds. Cold northerly winds persisted into mid-April in 2015, but did not result in extensive sea ice south of 58°N. The apparent mechanism that helped limit ice on the southeastern shelf was the strong advection of warm water from the Gulf of Alaska through Unimak Pass. This pattern has been uncommon, occurring in only one other year (2003) in a 37-year record of estimated transport through Unimak Pass. During years with no sea ice on the southern shelf (e.g. 2001–2005, 2014–2016), the depth-averaged temperature there was correlated to the previous summers ocean temperature.