Over the past several decades, the chemical
environment of our seas has evolved as a result of human activities and evidence of the severe biological effects of contaminants can be found throughout the North Atlantic and adjacent seas.
The use of the antifouling agent tributyltin (TBT) caused some populations of the gastropod Nucella lapillus in the UK to disappear, with up to 100% of the females being sterile in some of the remaining populations.
Exposure to sediments contaminated with olycyclic aromatic hydrocarbons (PAHs), chemicals that occur naturally in coal, crude oil, and gasoline, caused flatfish species in the Puget Sound (Northwest US) to develop neoplasms (tumour developments) in up to 25% of the population.
The accumulation of persistent organic pollutants (POPs), toxic substances composed of organic (carbon-based) chemical compounds and mixtures, including industrial chemicals like PCBs and pesticides like DDT, caused reproductive failure in the Baltic Sea grey seal population, leading to a significant population decrease in the 1980s.
Reproductive failure in the European killer whale populations have been associated with the accumulation of organic pollutants (particularly PCBs), in blubber.
Industrial waste products, household cleaning products, agricultural pesticides and herbicides, and medications all carry chemicals to the seas. In 2017, the European Chemicals Agency (ECHA) estimated that there were more than 100,000 chemicals on the market. With new substances introduced each year, this number is increasing.
There has also been a general shift from high concentrations of a few chemicals to low concentrations of many. As shown, all these chemicals have the potential to affect individuals, populations, species, and communities through changes in e.g. growth, reproduction, and survival.
What effects do these contaminants have on marine biota? How can we holistically assess these effects? And what can be done to improve management of the marine environment? The latest Viewpoint from ICES makes several recommendations to be able to answer these questions.
Monitoring
Over the past two decades, how to monitor and quantify the impacts of chemical pollution has been under discussion in ICES Working Group on Biological Effects of Contaminants (WGBEC).
The group has developed this work through ICES/OSPAR Study Group on Integrated Monitoring of Contaminants
and Biological Effects (SGIMC) in 2011 and the ICON project in 2017 - laying the groundwork for the latest ICES VIEWPOINT: Assessment of biological effects of chemical pollution for better management of the marine environment.
In the Viewpoint, ICES advises to adopt biological effects methods for monitoring within the integrated chemical-biological monitoring and assessment framework as, “such a holistic approach provides a more realistic assessment of chemical pollution and its impacts". Along with increasing the understanding of contaminant interactions and effects, WGBEC develops integrated biological effects monitoring strategies, which are used to support international research and monitoring.
Ketil Hylland, University of Oslo, Norway, member of WGBEC, and lead author of the Background Report notes that, "All European countries with a coastline monitor for concentrations of contaminants in marine species and some for effects, but generally using a few methods. What this viewpoint advocates for is addressing a wide range of effects, covering the most important mechanisms of toxicity".
Methods
The main requirement for the proposed methods is that they are able to distinguish the effects of pollution from those of natural factors. "We must know that the response we measure is caused by chemical pollution", notes Hylland, "or at the very least be able to account for a confounder (e.g. gender)".
There are challenges to this approach, with the main one being the cost of monitoring for individual countries. However, some national programmes have already incorporated biological effects monitoring and this experience has been taken into account in developing the viewpoint and Hylland believes it will be beneficial that ICES promotes the strategy. Through WGBECs work, ICES has already contributed to a Europe-wide programme.
"I believe we are in a situation where there is increasing focus on effects", Hylland continues, "Some organizations and countries have pushed hard for using a risk-based approach, which in our view will not produce the data we need to manage our seas. The viewpoint strongly argues that field-based assessment is necessary."
