Low Chronic Additions of No. 2 Fuel Oil: Chemical Behavior, Biological Impact and Recovery in a Simulated Estuarine Environment

Abstract

Three long term experiments were conducted in estuarine microcosms with a water accommodated fraction of No. 2 fuel oil. The water column and benthic compartments (structure and processes) were assessed for impact of chronic oil concentrations (190 and 90 ppb in the water column), and recovery from exposure to 90 ppb oil concentration. Oil impacts were a function of concentration, oil residence time and temperature. The 190 ppb concentration reduced zooplankton; both 190 ppb and 90 ppb reduced benthic fauna. In 1 yr after additions ceased the benthic fauna did not recover from 90 ppb. Effects on and oil residence time in the water column were transitory; effects on and oil residence time in the benthos were long lasting. Effects on benthic fauna were most severe during the warm summer months. Hydrocarbon constitution, age, form and therefore toxicity in the estuary may or may not be equivalent to the No. 2 fuel oil used in these experiments. However, chronic water column concentrations of 100 ppb and sediment concentrations of 500 ppm which are commonly found at the heads of estuaries indicate a potential for benthic degradation due to hydrocarbons.

Recovery of a polluted estuarine system: a mesocosm experiment

“…hydrocarbons and phthalates) are stable in sediments for long periods of time (Jungclaus et al, 1978;Wade and Quinn, 1980). During experiments with Number 2 fuel oil, we observed very slow sedimentary degradation rates (Oviatt et al, 1982) as has been observed in the field (Sanders et al, 1980). Volatile organic components were elevated in Narragansett Bay with residence times on the order of 200 to 300 h and generally not present in the 3 mesocosm treatments, suggesting their sources were new inputs (Wakeham et al, 1982;Wakeham et al, 1983).…”

“…9). We expected that these polychaetes and bivalves would recolonize to field levels of abundance during the summer of 1980 as observed in previous experiments (Oviatt et al, 1982). Indeed, bivalve veligers and polychaete larvae were abundant in the water column throughout the summer indicating reproduction in all mesocosms (Fig.…”

“…2 ) . In situ concentrations of nitrogen inorganic nutrients (ammonia, nitrite plus nitrate, phosphate, silicate), particulate carbon and nitrogen and total system metabolism (for methods see Oviatt et al, 1982). Phytoplankton and macrobenthic fauna were sampled, preserved and counted monthly.…”

“…and June 1980. At the end of the experiment all sediments were sieved (3.2 mm) for larger organisms (Oviatt et al, 1982). Benthic respiration and nutrient release (ammonia, nitrite plus nitrate, phosphate and silicate) were sampled in August 1979, February 1980, June 1980, August 1980and April 1981 an incubation chamber which fits over the entire sediment surface (Oviatt et al, 1982).…”

Long-term changes in microphytobenthos in a Brittany estuary after the 'Amoco Cadiz' oil spill

“…Very few papers deal with the consequences of oil pollution on microphytobenthos communities, whereas numerous studies have been carried out on physiological responses to pollution of phytoplankton in culture (Parsons et al 1976, Prouse et al 1976, Hsiao 1978, artificial enclosures (meso-and microcosms) (Elmgren & Frithson 1982, Oviatt et al 1982, Skjoldal et al 1982, and in natural populations (Gordon & Prouse 1973, Vargo et al 1982. Phytoplankton responses to simulated or accidental pollution are diverse and depend upon the species, pollution level, nature of oil pollutant and environmental factors.…”