Dispersants Have Limited Effects on Exposure Rates of Oil Spills on Fish Eggs and Larvae in Shelf Seas

Early life stages of fish are particularly vulnerable to oil spills. Simulations of overlap of fish eggs and larvae with oil from different oil-spill scenarios, both without and with the dispersant Corexit 9500, enable quantitative comparisons of dispersants as a mitigation alternative. We have used model simulations of a blow out of 4500 m³ of crude oil per day (Statfjord light crude) for 30 days at three locations along the Norwegian coast. Eggs were released from nine different known spawning grounds, in the period from March 1st until the end of April, and all spawning products were followed for 90 days from the spill start at April first independent of time for spawning. We have modeled overlap between spawning products and oil concentrations giving a total polycyclic hydrocarbon (TPAH) concentration of more than 1.0 or 0.1 ppb (μg/l). At these orders of magnitude, we expect acute mortality or sublethal effects, respectively. In general, adding dispersants results in higher concentrations of TPAHs in a reduced volume of water compared to not adding dispersants. Also, the TPAHs are displaced deeper in the water column. Model simulations of the spill scenarios showed that addition of chemical dispersant in general moderately decreased the fraction of eggs and larvae that were exposed above the selected threshold values

Trophic level and fatty acids in harp seals compared with common minke whales in the Barents Sea

<p>The objectives of this study were to explore trophic levels and possible diet overlap between harp seals (<i>Pagophilus groenlandicus</i>) and common minke whales (<i>Balaenoptera acutoroostrata</i>) in the Barents Sea using stable isotopes of nitrogen (δ¹⁵N) and carbon (δ¹³C) and fatty acid analyses, and to explore the energy pathways from the plankton to the top predators. Blubber and muscle samples from 93 harp seals and 20 minke whales were collected in the southern Barents Sea in May 2011. The study showed that harp seals were at a higher trophic level than minke whales during spring. This supported previous diet studies suggesting a more fish-dominant diet for seals, as compared with the whales, at this time of the year. The stable isotopes and fatty acids indicated niche separation between the seals and the whales, and between different age groups of the harp seals. Older seals had fatty acid profiles more equal to minke whales as compared with younger seals. Furthermore, while the fatty acid profiles suggested that krill were of particular importance for the young seals, the profiles from older seals and whales suggested that fish dominated their diets.</p

Relative body burden (%) of select 2–6 ring PAHs and alkyl PAHs in larvae of cod exposed to ~9 μg/L tPAH, haddock exposed to WSF and haddock exposed to ~9 μg/L tPAH who hatched in the tank and that was dechorionated.

<p>NAP = naphthalene, FLU = fluorene, DBT = dibenzothiophene, PYR = pyrene, CHR = chrysene.</p

Coefficient of determination (R2) as a function of log KOW for the fit of a linear relationship between cyp1a induction and single compound body burdens.

<p>Coefficient of determination (R2) as a function of log KOW for the fit of a linear relationship between cyp1a induction and single compound body burdens.</p

Total PAH body burden (including alkyl clusters) measured in cod and haddock eggs at day 3 and day 9 of exposure.

<p>Total PAH body burden (including alkyl clusters) measured in cod and haddock eggs at day 3 and day 9 of exposure.</p

Relative body burden (%) of select 2–6 ring PAHs and alkyl PAHs in larvae of cod exposed to ~9 μg/L tPAH, haddock exposed to WSF and haddock exposed to ~9 μg/L tPAH who hatched in the tank and that was dechorionated.

<p>NAP = naphthalene, FLU = fluorene, DBT = dibenzothiophene, PYR = pyrene, CHR = chrysene.</p

Additional file 3: of Genomic architecture of haddock (Melanogrammus aeglefinus) shows expansions of innate immune genes and short tandem repeats

Figure S2. The terms that are significantly enriched for genes with trinucleotide tandem repeats in different species, those repeats that can vary in length without causing frameshifts in the protein. Only tests with P < 0.01 are colored. Red signifies enrichment, more trinucleotide repeats than expected, and blue purification, less than expected. The P-value is signified with color intensity with more bland color being less significant. White areas have no significant differences. (PDF 39 kb

Deviation in body burden (pg/embryo) of PAHs and alkyl PAH groups between day 9 and day 3 for an intermediate exposure concentration (~3 μg/L tPAH).

<p>Negative values indicate a decline in body burden of the compound group between the two time points. NAP = naphthalene, FLU = fluorene, DBT = dibenzothiophene, PYR = pyrene, CHR = chrysene.</p

Observed relationship between log <i>K</i>_OW and rate of decline in body burden concentration from day 3 to day 9 during exposure of crude oil exposed haddock embryos.

<p>The fitted line shows a third-degree polynomial fit for 3–6 ring compounds (blue circles). 2-ring PAHs (red circles) showed a linear increase with increasing log <i>K</i>_OW.</p

Additional file 1: of Genomic architecture of haddock (Melanogrammus aeglefinus) shows expansions of innate immune genes and short tandem repeats

Note S1 and Table S1-S10. (PDF 595 kb