4f4c4942-4343-5764-6473-313130313231 English Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2026-03-03T16:32:11.777Z NRW 1.0 wel British National Grid (EPSG::27700) Oil contamination of gannets and their nests on Grassholm subsequent to the sea Empress oil spill. Oil contamination of gannets and their nests on Grassholm subsequent to the sea Empress oil spill. Halogi huganod a'u nythod ag olew ar Ynys Gwales yn sgil gollyngiad olew'r Sea Empress 1998-01-31 NRW_DS110121 Grassholm, situated 23 km WNW of the entrance to Milford Haven, supports the worlds third largest gannetry with an estimated population of 30,000 pairs. Gannet nests are perennial constructions 30-60 cm high, built out of seaweed, grass and items of floating debris collected from the sea. Almost all gannet nests, therefore, contain man-made materials, often in substantial quantities. Dataset contains results of investigations to assess whether nest material contaminated with oil from the Sea Empress was incorporated into gannet nests on Grassholm and, if so, whether there was any effect on fertility or productivity in contaminated nests. At the time of the Sea Empress incident it is estimated that 80 percent of the adult breeding population of gannets on Grassholm had returned to the colony. On a ship based survey between the 25-29/2/96, immediately after the spill, only 0.39 percent of 1,279 gannets recorded showed some degree of oiling, and a similar percentage were observed carrying nest material. The small proportion carrying nest material suggests that at that time they had not started nest building. Grassholm, situated 23 km WNW of the entrance to Milford Haven, supports the worlds third largest gannetry with an estimated population of 30,000 pairs. Gannet nests are perennial constructions 30-60 cm high, built out of seaweed, grass and items of floating debris collected from the sea. Almost all gannet nests, therefore, contain man-made materials, often in substantial quantities. Dataset contains results of investigations to assess whether nest material contaminated with oil from the Sea Empress was incorporated into gannet nests on Grassholm and, if so, whether there was any effect on fertility or productivity in contaminated nests. At the time of the Sea Empress incident it is estimated that 80 percent of the adult breeding population of gannets on Grassholm had returned to the colony. On a ship based survey between the 25-29/2/96, immediately after the spill, only 0.39 percent of 1,279 gannets recorded showed some degree of oiling, and a similar percentage were observed carrying nest material. The small proportion carrying nest material suggests that at that time they had not started nest building. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Countryside Council for Wales (CCW) Countryside Council for Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW enquiries@naturalresourceswales.gov.uk http://naturalresourceswales.gov.uk/splash?orig=/ Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Species distribution GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme Celtic Sea oil developments oil pollution gannets sula bassana (morus bassana) nests Grassholm Sea Empress pollution (see also specific types of pollution eg. oil pollution) marine and freshwater inventory oil contamination fertility oil derived hydrocarbons polycyclic aromatic hydrocarbons (PAHs) long chain paraffins NRW Thesaurus 2023-12-31 geonetwork.thesaurus.local.theme.converted_nrw-keywords Bird reproduction Bird taxonomy-related abundance per unit area of surface SeaDataNet Parameter Discovery Vocabulary 2021-01-06 geonetwork.thesaurus.external.theme.rdf+xml oil spillage productivity Integrated Public Sector Vocabulary 2013-04-03 geonetwork.thesaurus.external.theme.subjects NRW SMNR Vocabulary 2023-12-27 geonetwork.thesaurus.local.theme.converted_nrw-smnr-keywords There are no access restrictions on this data. NRW may release, publish or disseminate it freely. no limitations © CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose. English biota SeaVoX Vertical Co-ordinate Coverages 2021-01-06 benthic boundary layer Wales (WLS) -5.94602325 -5.2731589 51.53587481 51.94788872 1996-04-07 1997-04-09 Oil contamination of gannets and their nests on Grassholm subsequent to the sea Empress oil spill Documents Report (MS Word, pdf-format) Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 This dataset has not been assessed for conformance to the referenced INSPIRE regulation. false Oiling rate of adult gannets within the colony was determined by scoring approximately 1000 birds in a subsection of the colony. Oil contamination was taken as any visible oil spot. Counts were made using binoculars on the 7/4/96, 12/5/95 and 9/4/97 (Bullock/RSPB, 1998). A measure of productivity obtained by scoring approximately 1000 nests. Success was defined as the production of a live offspring i.e. that an egg hatched. For the purposes of a 'site' control, ten samples were obtained in May 1996 from nests on St Kilda, the worlds largest gannetry, situated approximately 60 km west of the Outer Hebrides and 700 km NNW of Grassholm. Samples from Grassholm were collected on the 8/11/96. Nest piles were cut in half vertically and approximately 30-50 cm3 of material removed from the upper 5cm.subset of 14 samples of nest material were selected for this preliminary study, focusing on failed nests on Grassholm (7 samples) in order to determine in the first instance whether PAHs and paraffins would be detectable in the nest material. Three samples from successful nests on Grassholm were included for comparison, in addition to four samples of nest material from the remote location of St Kilda. Extracts were analysed by GC/MS, using standards to quantify range of PAHs and long-chain hydrocarbons. Extraction efficiency for each of the analytes was determined by extraction of spiked samples. Increased monitoring effort and impact assessment following the Sea Empress oil spill. The only data associated with this project is held within the report. Oiling rate of adult gannets within the colony was determined by scoring approximately 1000 birds in a subsection of the colony. Oil contamination was taken as any visible oil spot. Counts were made using binoculars on the 7/4/96, 12/5/95 and 9/4/97 (Bullock/RSPB, 1998). A measure of productivity obtained by scoring approximately 1000 nests. Success was defined as the production of a live offspring i.e. that an egg hatched. For the purposes of a 'site' control, ten samples were obtained in May 1996 from nests on St Kilda, the worlds largest gannetry, situated approximately 60 km west of the Outer Hebrides and 700 km NNW of Grassholm. Samples from Grassholm were collected on the 8/11/96. Nest piles were cut in half vertically and approximately 30-50 cm3 of material removed from the upper 5cm.subset of 14 samples of nest material were selected for this preliminary study, focusing on failed nests on Grassholm (7 samples) in order to determine in the first instance whether PAHs and paraffins would be detectable in the nest material. Three samples from successful nests on Grassholm were included for comparison, in addition to four samples of nest material from the remote location of St Kilda. Extracts were analysed by GC/MS, using standards to quantify range of PAHs and long-chain hydrocarbons. Extraction efficiency for each of the analytes was determined by extraction of spiked samples. Increased monitoring effort and impact assessment following the Sea Empress oil spill. The only data associated with this project is held within the report.