Assessment of wet mass, dry mass, ash mass, ash free dry mass, carbon content and nitrogen content of selected coastal bird species and harbor seal tissues

But top predators are difficult to include in network analyses because their biomass in ash free dry weight or carbon content is missing. Regression equations were determined for the relationships between fresh weight and dry weight, ash free dry weight, carbon and nitrogen contents respectively for six of the most abundant bird species in the Wadden Sea (Calidris canutus, Limosa lapponica, Haematopus ostralegus, Chroicocephalus ridibundus, Larus canus, Anas penelope) and harbor seals (Phoca vitulina).

The relationships for all species were interpreted as linear through the origin. Carbon content vs. fresh weight ratios for birds ranged from 0.16 ± 0.01 to 0.22 ± 0.02. Carbon content vs. fresh weight ratio was 0.17 ± 0.02 on average for harbor seals.