Why is it important?
Statistics and/or aggregation of basic products provide meaningful insights when day to day variation is high. Maps of seasonal or yearly averages can be used to compare year to year variation and spatial aggregation of pixels can be used for comparison of different areas or for the purpose of suitability analyses. Shellfish growth for example, peaks during spring season when temperatures rise and phytoplankton starts to bloom. Inter-annual comparison of spring season averages can give insight in shellfish growth patterns.
What does CoastObs offer?
CoastObs provides seasonal and annual maps of average food quantity and food quality for shellfish. The aggregated maps are based on the 300m Sentinel 3 basic products: the ratio Chlorophyll-a relative to Total Suspended Matter is used as a measure for food quality, and chlorophyll-a for food quantity. Maps like these are helpful to compare annual variation of important drivers for shellfish growth and also to gain insight in spatial variation of these parameters.
How was the data validated?
For aggregation and statistics, the validated basic products I Chlorophyll-a and II Total Suspended Matter are used. All valid pixels of a study area within a certain time frame are averaged to create one map representing that specific time frame or season. In case of food quality, the average value of each Chlorophyll-a pixel is divided by the average pixel value of Total Suspended Matter to create a map of average Food Quality for an area.
Case study example: Seasonal food quantity in the Wadden Sea
Figure 1. Maps of average spring Chl-a concentrations (left) and the average mussel growth rate of the same two years (right)
Limitations
Linked to limitations of basis products Chlorophyll-a and Total Suspended Matter.