DigitalCommons@Linfield

Tidal Variation in Nitrogen Cycling in Oregon Sponges

Jereld R. Nicholson Library

As filter feeders, marine sponges are closely integrated with their environment. Sponges also host many diverse species of bacteria that carry out a gamut of metabolic processes, including several nitrogen transformations. The variable nature of tidal exchanges can influence the biogeochemicals available for the sponge and its associated microbes to obtain from the environment. As ambient nutrient concentrations change, it is suggested that the pumping rates of the sponge will change, thus altering the activity of the symbionts. To explore these hypotheses, ambient and exhalent water samples were collected at both high tide and low tide in Netarts Bay, Oregon. To assess pumping rates, transect images between tides were analyzed for changes in oscula diameter within species. Nitrate, ammonia, and total nitrogen concentrations were analyzed via spectroscopy. Transect results demonstrated decreased oscula diameter and therefore decreased pumping rates during high tide and inverse results at low tide. Significant variation was found between inhalant and exhalent nitrate, ammonia, and total nitrogen values between species and between tides. This suggests that ambient nitrogen concentrations influence internal nitrogen cycling, but varies between species. These results suggest that sponges and their associated microbial communities adjust their metabolism based on tidal influences.