Provenance & quality
Sediment colloidal carbohydrate concentration 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 the sample core is stored below -80 degree centigrade. The sample is weighed to determine wet weight and freeze dried to remove all water. Colloidal carbohydrate concentration is determined using the Dubois Phenol-Sulphuric assay. A sediment sub-sample (50-500mg, depending on site) is taken from dried contact core sediment and known volume of distilled water is added. Sample is vortexed and centrifuged then a set volume of supernatant is removed. Concentrated sulphuric acid and 5 percent phenol are added to the supernatant sample ensuring the ratio of sample: phenol: acid is kept at 1:1:5 by volume. Allow 35mins for colour to develop. Decant the samples into cuvettes and read the absorbance at 486.5nm on Thermo Biomate 5 spectrophotometer. Use figures from regression analysis of glucose standards to calculate colloidal carbohydrate concentration expressed as glucose equivalents in micrograms per gram (µg g-1). Note: zeroes indicate colloidal carbohydrate concentration below detectable level. 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).