Biomass Pyramids of Marine Mesozooplankton Communities as Inferred From Their Integrated Trophic Positions

Biomass pyramids in natural food webs provide insights into multitrophic ecosystem functioning. We measured the integrated trophic position (iTP), which reflects the average efficiency of biomass transfer through trophic pathways, of 14 mesozooplankton communities in the western North Pacific. Compound-specific nitrogen isotope analysis of amino acids for composite mesozooplankton biomass indicated that the iTP values of marine mesozooplankton communities and their biomass pyramids are essentially controlled by biodiversity, body weight, and species turnover. Offshore communities with lower diversity and higher iTP were dominated by large copepods with slow turnover, such as Neocalanus , whereas nearshore communities with higher diversity and lower iTP were characterized by several smaller, fast turnover species belonging to Calanus , Paracalanidae, Eucalanidae, and Metridinidae. The observed iTP values (2.36 ± 0.32) indicate different topologies in biomass pyramids in different sites, where inverted pyramids are found in less diverse communities. The results also suggest that iTP can be linked to food chain length (FCL), a conventional proxy for the biomass pyramid. Combining iTP and FCL in the future studies will be a powerful approach to better understand factors controlling food web structure and dynamics.