OSPAR Science Agenda Knowledge Gap Portal

Knowledge gap description: For a more robust assessment, spatial and temporal confidence of the results should be developed and implemented. This will lead to targeting the location which requires a better sampling effort. Spatial and temporal confidence indices (which will be implemented in future assessments) will address the sampling effort in the pelagic habitats within OSPAR Regions. These spatial and temporal confidence indices will be implemented in future assessments.

Knowledge gap description: For a more robust assessment of the pelagic habitat, information on phytoplankton community structure (this assessment) should be complemented by other parameters, such as total community biomass/abundance (PH2) and the dynamics of phytoplankton functional groups (PH1/FW5). Thus, a more holistic assessment of plankton dynamics could be obtained and possibilities for an integrated overall pelagic habitat assessment result should be investigated further.

Knowledge gap description: Future assessments will be improved by incorporating the Hill concept so that the influence of sampling effort is factored into indicator calculation.

Knowledge gap description: Include additional data sets: characterising marine plankton by manual counting and identifying plankton in a small sample of seawater through a microscope has its limitations. Additional methods could include state-of-the-art (semi-)automated methods and molecular methods. Combining multiple methods may help fill the gaps in microscopic examinations and applying complementary methods will facilitate monitoring the full-size range of the phytoplankton community.

Knowledge gap description: The knock-on effects of change in feeding guilds across assemblages (plankton, benthos, top predators) requires further research.

Knowledge gap description: Top-predators (e.g. seabirds, cetaceans) and organisms lower in the food web (e.g. benthos, plankton) have not yet been classified into guilds but diet databases for such taxa do exist and could be included in future.

Knowledge gap description: Comparison should be made to relevant pelagic habitat and food web indicators (FW2 and PH2) to better address the extent of changes.

Knowledge gap description: The candidate indicator, size composition and spatial distribution of zooplankton (FW6), was not assessed because of lack of data.

Knowledge gap description: Greater North Sea (Region II) - Variable salinity ecosystems / Plankton community assessment: Plankton monitoring datasets were available for a limited number of assessment units, with significant gaps in time series. Lower confidence must therefore be assigned to these results, particularly for the zooplankton lifeform time-series.

Knowledge gap description: Greater North Sea (Region II) - Coastal ecosystems / Plankton community assessment: Data used to assess trends exhibited a high degree of confidence and the majority of assessment units were well represented, except for the gelatinous zooplankton lifeform. However, a high degree of variability resulted from linking trends in lifeform abundance with environmental pressures, and thus the associations with change in sea surface temperature and salinity lacked confidence.

Knowledge gap description: Celtic Seas (OSPAR Region III): Variable salinity ecosystem /Plankton community assessment. For the Common Indicator Assessment on Changes in Phytoplankton and Zooplankton Communities (PH1 / FW5), there was very low representation of assessment units for all zooplankton lifeforms. There are also gaps in existing relevant literature: scarce literature on primary production trends in the area and no investigation of the link between ocean acidification and primary production over long-term timescales. It is unclear if the decrease in primary production in the variable salinity and coastal habitats assessed here is due to decreasing pH or if it is the cause of decreasing pH. Further investigations is needed to understand links between phytoplankton activity (production and respiration) and long-term concentration of dissolved inorganic carbon and anthropogenic carbon dioxide.

Knowledge gap description: Celtic Seas (OSPAR Region III): Coastal ecosystems / Plankton community assessment. Common Indicator Assessment on Changes in Phytoplankton and Zooplankton Communities (PH1 / FW5): No data were available for the gelatinous zooplankton lifeform. As in variable salinity habitats, it is unclear whether the decrease in primary production detected was the consequence of ocean acidification.

Knowledge gap description: Celtic Seas (OSPAR Region III): Shelf ecosystems / Plankton community assessment. Common Indicator Assessment on Changes in Phytoplankton and Zooplankton Communities (PH1 / FW5): No data were available for the gelatinous zooplankton lifeform.

Knowledge gap description: Bay of Biscay and Iberian Coast (OSPAR Region IV): Variable salinity habitat / Plankton community assessment - There were no suitable plankton monitoring data available to evaluate the pelagic habitat indicators. For the Candidate Indicator Pilot Assessment of Primary Productivity (FW2), the assessment was also not possible because of lack of data.

Knowledge gap description: Bay of Biscay and Iberian Coast (OSPAR Region IV): Coastal ecosystems / Plankton community assessments - For coastal habitats, only phytoplankton data were available to inform Common Indicator Assessment on Changes in Phytoplankton and Zooplankton Communities (PH1/FW5). For the Candidate Indicator Pilot Assessment of Primary Productivity (FW2), assessment was also not possible because of lack of data.

Knowledge gap description: Bay of Biscay and Iberian Coast (OSPAR Region IV): beyond shelf / Plankton community assessment. Common Indicator Assessment on Changes in Phytoplankton and Zooplankton Communities (PH1 / FW5): No data were available for the gelatinous zooplankton lifeform so it was not assessed.

Knowledge gap description: Bay of Biscay and Iberian Coast (OSPAR Region IV): beyond shelf / Plankton community assessment. Candidate Indicator Pilot Assessment of Primary Productivity (FW2) - pilot assessment results indicated significant downward trend in primary production. Spatial assessment was limited to one area representing 20% of all sub-divisions in the habitat, resulting in low confidence in those results. Future projection of primary production in the Bay of Biscay and Iberian Coast is subject to large uncertainty.

Knowledge gap description: The assessment needs to build evidence of how nitrate and phosphate ratios lead to changes in phytoplankton communities which negatively impact the efficiency of the ecosystem services those communities provide. An improved understanding of nearshore plankton dynamics and the influence of river flows can inform the measures required to manage the nitrogen inputs from sources such as urban wastewater and agriculture.