Provenance & quality
Sediment chlorophyll content was determined through the collection of contact cores. Contact cores use liquid nitrogen to freeze the top 2mm of the sediment surface, excess unfrozen sediment is removed and sample core is stored below -80 degree centigrade to ensure preservation of pigments. The sample is freeze dried to remove all water and a sub-sample taken. Acetone is added to the sediment sample and stored at -20 degrees centigrade for 48 hours to allow extraction of pigments. The sample is centrifuged and supernatant is analysed in a spectrophotometer for absorption at wavelengths 630, 647, 664 and 750 nanometres (nm). Values for chlorophyll a, b and c1+ c2 are expressed as micrograms per gram of sediment. The location of the sample sites was determined by randomly allocated quadrats. Twenty two 1 x 1 m quadrats were randomly allocated to each mudflat and saltmarsh site using R (R Development Core Team, 2014) to specify four different spatial scales (A = 1 quadrat only, B = 3 quadrats at 1 m to 10 m apart, C = 6 quadrats at 10 m to 100 m apart, D = 12 quadrats at 100 m to 1000 m or site maximum).