Tidal Variation in Nitrogen Cycling in Oregon Sponges

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

Marine Sponges as Bioindicators of Nitrogen within Estuaries on the Oregon Coast

As filter feeders, sponges are highly integrated with their environment. Many sponges also host diverse communities of bacteria, including many that are hypothesized to carry out a variety of nitrogen transformations. The presence of these bacteria makes sponges an integral part of the nitrogen cycle in their habitats and suggests that sponges are an excellent bioindicator of environmental conditions. To test these hypotheses, we collected sponge tissue from two Oregon estuaries and extracted microbial DNA from these samples. To assess bacterial diversity, we performed Denaturing Gradient Gel Electrophoresis (DGGE) on a fragment of the 16S gene. We also examined nitrogen cycling in sponges by examining the sponge samples for the presence of the amoA and nirS genes, which encode for enzymes in the nitrification and denitrification pathways, respectively. DGGE results showed diverse bacterial communities, with clear differences between the sites. The results also showed little variation within sites, but were suggestive of seasonal variation. Both functional genes were present in all five species of sponge that we collected. These results suggest that sponges and their associated bacterial communities play a critical role in nitrogen transformations within these bays and that these sponge-associated bacterial communities are bioindicators of environmental variation

Newport Transect 01, Image 02

This still image was captured from a video transect in Newport, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.http://digitalcommons.linfield.edu/biol_transects_photos/1001/thumbnail.jp

Newport Transect 01, Image 10

This still image was captured from a video transect in Newport, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.https://digitalcommons.linfield.edu/biol_transects_photos/1009/thumbnail.jp

Newport Transect 01, Image 06

This still image was captured from a video transect in Newport, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.https://digitalcommons.linfield.edu/biol_transects_photos/1005/thumbnail.jp

Netarts Transect Video 05

This video transect was taken in Netarts, Oregon. Researchers are able to use this video to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms

Newport Transect Video 01

This video transect was taken in Newport, Oregon. Researchers are able to use this video to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms

Netarts Transect 02, Image 10

This still image was captured from a video transect in Netarts, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.https://digitalcommons.linfield.edu/biol_transects_photos/1049/thumbnail.jp

Newport Transect 01, Image 09

This still image was captured from a video transect in Newport, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.https://digitalcommons.linfield.edu/biol_transects_photos/1008/thumbnail.jp

Newport Transect 01, Image 08

This still image was captured from a video transect in Newport, Oregon. Researchers are able to use this image to quantify relative abundance and diversity of benthic (i.e. bottom-dwelling) organisms.https://digitalcommons.linfield.edu/biol_transects_photos/1007/thumbnail.jp