Abstract The quantitative contribution of marine fishes to global biogeochemical cycles, particularly the transport of carbon to the ocean’s interior, is poorly understood. Half of the current uncertainty relates to parameterization of metabolic processes, including respiratory CO2, dissolved excreta and particulate organic waste pathways. This analysis experimentally compares the mass-specific and relative contribution of each of these pathways using the pelagic coastal and estuarine species Menidia menidia. Although respiratory production is steady over time, contributing over half of the carbon loss over a 6–12 h period, both particulate organic carbon (POC) and dissolved organic carbon (DOC) were not linear in production. “Gut loads” of POC occurred within the first two hours of the experiment, correlating with an initial spike in DOC, and contributing to about 30% of the carbon flux. There was appreciable production of DOC over the duration of the experiment, resulting in 12.5% of the total carbon waste, suggesting this pathway should not be excluded from modeling efforts.
Maas et al. (Fri,) studied this question.