Forsøksdyr: Acute and long-term effects of burned oil residues on Northern shrimp (Pandalus borealis)


Godkjenningsdato 21.02.2020

Godkjenningsperiode 21.02.2020-06.06.2020

This work is part of the ARCEx project financed by NFR and industry partners and hosted by UiT Norway. NORCE Environment is partner in WP3 on the effect of petroleum discharges on key species of northern ecosystems.

The objective of this study is to gain knowledge on acute (LC50) and long-term effects of burned oil residues on pelagic (larvae) and benthic (adults) life stages of Northern shrimp (Pandalus borealis).

In-situ burning (ISB) is one of the oil spill responses (OSR) in offshore environments, particularly relevant for the Northern areas. It basically involves removal of oil by burning the spilled oil on the sea surface. The released oil is rapidly converted into combustion products while a small percentage of unburned oil and burned residues remain on the surface, within the water column, or sink to the seafloor (Bullock et al., 2019). ISB may increase the concentrations of large poly-aromatic hydrocarbons (PAHs; high ring number), while reducing small PAHs (low ring number) (Fritt-Rasmussen et al., 2015). Burned residues, either floating or sinking, may pose a risk of toxicity or contamination to organisms in the water column and on the seafloor. Floating residues may be ingested or cause fouling of gills (Fritt-Rasmussen et al., 2016), while sinking residues may affect benthos, mainly via smothering (NOAA, 2019). Acute aquatic toxicity of burned residues has been reported to be low (NOAA, 2019). However, Faksness and Altin (2019) found that the acute specific toxicity of WAF of ISB residue was more toxic to Calanus finmarchicus nauplii than WAF of fresh oil after 72 h exposure using an ultra-low sulphur fuel oil. Knowledge on chronic toxicity and long-term effects of burned residues on benthic and pelagic marine organisms / life stages is largely missing. We propose to use the Northern shrimp Pandalus borealis, an ecologically and economically important species in Norwegian waters, to address this knowledge gap. Firstly, during their life cycle, both pelagic and (epi-)benthic stages are present. Secondly, this species has repeatedly been shown to be sensitive to oil exposure (Arnberg, 2015; Arnberg et al., 2018; Bechmann et al., 2010; Taban et al., 2007). Effects prolonged beyond exposure during recovery (Arnberg et al., 2019; Keitel-Gröner et al., 2020), an aspect largely ignored in standard toxicity testing. Thirdly, the species has been shown to be suitable for laboratory work and NORCE researcher have many years of experience working with both, larval (pelagic) and adult (epibenthic) stages.

In total 240 adult shrimp are needed, 200 of these will be used in exposure experiments, while 40 adult shrimp are needed to provide larvae for exposure experiments. Additionally, 4380 larvae will be used, 3900 during exposure experiments and the remaining 480 to study carry-over effects on shrimp larvae exposed as embryos.

There are currently no effective replacement methods available to avoid the use of shrimp in this project. The minimum number of animals required to achieve acceptable statistical strength will be used.

 

Begrunnelse for etterevalueringen

Betydelig belastende.

Etterevaluering

Forsøksmålet var å få kunnskap om akutte (LC50) og langsiktige effekter av brente oljerester på pelagiske (larver) og bentiske (voksne) livsfaser av reker (Pandalus borealis). Forsøkene var vellykkede og de foreløpige resultatene viser at giftigheten av brent olje er mindre enn av fersk olje, med hensyn til både akutte og langsiktige effekter. Resultatene skal brukes til å velge oljevern tiltak med den beste netto miljøgevinsten i dag og fremover (e.g. som NEBA – Net Environmental Benefit Analysis).
Belastningsgrad for voksne reker var lav mens belastningsgrad for rekelarvene var moderat under forsøket. Totalt antall dyr brukt var mindre en oppgitt i søknaden på grunn av forandringer i den eksperimentelle prosedyren som tok sikte på å redusere antall dyr som trengtes. Dette ble foreslått av Mattilsynet under evalueringen av søknaden. Opprinnelig ble det søkt om å få bruke 240 voksne reker og 4380 rekelarver, men det faktiske forbruket var henholdsvis 230 og 2085.
Forsøket ble kjørt med alle tiltak på plass for å holde belastningsgraden så lav som mulig og håndteringen av dyrene så lite belastende som mulig. Det finnes fremdeles ikke noe alternative til eksponeringseksperimenter for å svare på forsøkets formål, og under forsøket ble det heller ikke oppdaget forhold av betydning for 3R