Species-specific wet-dry mass calibrations for dominant Northeastern Pacific Ocean macroalgae and seagrass

Macroalgae and seagrasses form the base of productive ecosystems in the Northeastern Pacific Ocean. Often, ecological research on macroalgae, seagrasses, and sea wrack requires the conversion of biomass from wet to dry to create consistency across investigations. This process, however, can be destructive, impractical, time consuming, and labour intensive. We collected samples of twelve common Northeastern Pacific Ocean seaweed species (Alaria marginata, Codium fragile, Egregia menziesii, Fucus distichus, Macrocystis pyrifera, Mazzaella spp., Nereocystis luetkeana, Pterygophora californica, Pyropia spp., Ulva spp., and the seagrasses Zostera marina and Phyllospadix spp.) in two states: wet and fresh, or aged and partially desiccated. We weighed, dried, and compared samples, finding that many species displayed a strong (R-2 > 0.8) and predictable linear relationship between wet and dried conditions. In contrast, half the aged samples did not have a significant relationship between partially desiccated and dried conditions. Our results provide practical wet weight to dry weight ratios for many species, and with further research, a reliable set of species-specific wet to dry weight ratios for all species could be established. Wet to dry weight ratios are useful for macroalgae, seagrass, and sea wrack research or commercial applications and would reduce the need to conduct extensive wet-dry calibrations in each study.