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Table 5 List of various fatty acid-based trophic marker indices

From: Dietary preferences of brachyuran crabs from Taiwan for marine or terrestrial food sources: evidence based on fatty acid trophic markers

Carnivory Index \( {I}_{Ca}=\frac{18:1\left(n-9\right)}{\left[16:1\left(n-7\right)+16:4\left(n-1\right)+18:1\left(n-7\right)+18:2\left(n-6\right)+18:3\left(n-3\right)+18:4\left(n-3\right)+20:4\left(n-6\right)+20:5\left(n-3\right)\right]} \)
Chlorophyta Index ICh = 18:1(n − 7) + 18:3(n − 3)
Phaeophyceae Index IP = 18:4(n − 3)
Rhodophyta Index \( {I}_R=\frac{20:5\left(n-3\right)}{\left[16:0+18:0+22:6\left(n-3\right)\right]} \)
Bacillariophyceae Index IB = 16:1(n − 7) + 16:4(n − 1)
Vascular Plant Index IV = 18:2(n − 6)
16:0/IV \( 16:0/{I}_V=\frac{16:0}{18:2\left(n-6\right)} \)
Σalgae FA/IV \( {I}_T=\frac{\left[16:1\left(n-7\right)+16:4\left(n-1\right)+18:1\left(n-7\right)+18:3\left(n-3\right)+18:4\left(n-3\right)+20:4\left(n-6\right)\right]}{\ 18:2\left(n-6\right)} \)