Effects of dispersed oil on reproduction in the cold water copepod Calanus finmarchicus (Gunnerus)

Abstract

Following a 120-h exposure period to 3 concentrations of oil dispersions (0.022 mg L−1, 1.8 mg L−1, and 16.5 mg L−1, plus controls) generated from a North Sea crude oil and a subsequent 21-d recovery, mortality, and several reproduction endpoints (egg production rates, egg hatching success, and fraction of females participating in reproduction) in Calanus finmarchicus were studied. Concentration-dependent mortality was found during exposure, averaging to 6%, 3%, 15%, and 42% for the controls and 3 exposure levels, respectively. At the start of the recovery period, mean egg production rates of surviving females from the highest concentrations were very low, but reproduction subsequently improved. In a 4-d single female reproduction test starting 13 d postexposure, no significant differences in egg production rates or hatching success were found between reproducing control and exposed copepods. However, a significantly lower portion of the surviving females from the highest exposure participated in egg production. The results indicate that although short-term exposure to oil-polluted water after an oil spill can induce severe mortality and temporarily suspend reproduction, copepods may recover and produce viable offspring soon after exposure. The results might imply that for C. finmarchicus populations, the impact from short-term exposure to an oil spill might be predicted from acute mortality and that delayed effects make only a limited contribution to population decrease.

Ingestion and sublethal effects of physically and chemically dispersed crude oil on marine planktonic copepods

“…Although negative short-term effects of crude oil spills on zooplankton are generally acknowledged, long-term effects of crude oil pollution and the capacity for recovery by zooplankton communities are still important questions needing further attention (Olsen et al 2013). The long-term impact of oil on zooplankton communities likely depends on the specific environmental characteristics of the affected area and species composition of the planktonic community.…”

Relative sensitivity of Arctic species to physically and chemically dispersed oil determined from three hydrocarbon measures of aquatic toxicity

“…TPH-based toxicity for a diversity of fish and aquatic invertebrates has been used as a consistent metric for evaluating the relative sensitivity of aquatic species to oil products (e.g., Barron et al, 2013;Bejarano et al, 2014;de Hoop et al, 2011). Toxicity studies of individual hydrocarbon compounds, chemical dispersant-only tests, and the relatively limited studies on physically and chemically dispersed oil products using key pelagic Arctic species have provided insights into their relative sensitivity (de Hoop et al, 2011;Gardiner et al, 2013;Hansen et al, 2014;Hansen et al, 2011;Olsen et al, 2013a;Olsen et al, 2011), and have facilitated comparative assessments based mostly on constant exposures (Camus et al, 2015;de Hoop et al, 2011;Olsen et al, 2011). However, previous comparisons have not included toxicity data of chemically dispersed oil products or have focused solely on spiked declining oil exposures intended to represent typical conditions following surface oil spills.…”

Modeling filtration of dispersed crude oil droplets by the copepod Calanus finmarchicus

“…Experiments show that filtered oil is excreted with feces (Nordtug et al, 2015;Olsen et al, 2013), and, at minimum, two paths are possible: 1) Fecal pellets with oil droplets may sediment and deposit on the seabed, or 2) Fecal pellets and oil droplets may be degraded in the water column. Copepod feces is extensively degraded in the photic zone (Viitasalo et al, 1999;Bathmann et al, 1987).…”