National Performance Framework - Clean Seas Indicator 2016

The Clean Seas Indicator for 2016 is 90%. This means that 90% of assessments of metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in biota and sediment in Scottish marine waters show concentrations that are unlikely to harm marine organisms. The Indicator in unchanged compared to its baseline value in 2015.

The Indicator is calculated by assessing the concentrations of cadmium, lead, mercury, PAHs and PCBs in biota and sediment in three¹ regions: the Northern North Sea, Minches and Western Scotland and Irish Sea (Clyde & Solway). Of the 30 possible assessments, 27 (90%) show acceptable concentrations and 3 show unacceptable concentrations. These are tabulated below with a ✓ indicating acceptable and a ✕ indicating unacceptable.

compartment	region	cadmium	lead	mercury	PAHs	PCBs
biota	Northern North Sea	✓	✓	✓	✓	✓
biota	Minches and Western Scotland	✓	✓	✓	✓	✓
biota	Irish Sea (Clyde & Solway)	✓	✓	✓	✓	✓
sediment	Northern North Sea	✓	✓	✓	✓	✓
sediment	Minches and Western Scotland	✓	✕	✓	✓	✓
sediment	Irish Sea (Clyde & Solway)	✓	✕	✕	✓	✓

The thresholds used to assess whether levels are acceptable differ between contaminants and biota / sediment. Environmental Assessment Criteria (EAC) are used for PCBs in biota and sediment and for PAHs in biota; Effects Range Low (ERL) are used for metals and PAHs in sediment; and European Commission food standards (EC) are used for metals in biota. More information can be found here for biota and sediment.

The raw data used in the assessments can be downloaded here.

Full details of the assessments are available as follows:

• metals in biota
• metals in sediment
• PAHs in biota
• PAHs in sediment
• PCBs in biota
• PCBs in sediment

These describe the statistical methodology used, and present regional assessments of trends, status with respect to the EAC, ERL or EC, and status with respect to the Background Assessment Concentration, a more stringent threshold used to assess whether concentrations are at background levels.

¹ The Clean Seas Indicator originally also included contaminant assessments from a fourth region, the Scottish Continental Shelf. However, it was difficult to get adequate spatial coverage in this region so it was dropped from the Indicator in 2018. At the same time, all previous values of the Indicator were recalculated using the three regions considered here. The original report for 2016, including assessments from the Scottish Continental Shelf, can be found here.↩