Patterns in phytoplankton and benthic production on the shallow continental shelf in the northeastern Gulf of Mexico. (15th May 2019)

• Record Type: Journal Article
• Authors: Cesbron, Florian; Murrell, Michael C.; Hagy, Melissa Ederington; Jeffrey, Wade H.; Patterson, William F.; Caffrey, Jane M.
• Is Part Of: Continental shelf research. Volume 179(2019)
• Page Start: 105
• Page End: 114
• Publication Date: 2019-05-15
• Subjects: Dissolved oxygen -- Benthic microalgae -- Phytoplankton -- Respiration -- Northeastern Gulf of Mexico; Continental shelf -- Periodicals; Submarine geology -- Periodicals; 551.41
• DOI: 10.1016/j.csr.2019.04.003
• Languages: English
• ISSNs: 0278-4343

Abstract

Abstract: Shallow continental shelves support productive pelagic and benthic communities. This study examined primary productivity at a shallow shelf region in the northeastern Gulf of Mexico focusing on the effect of light on water column and benthic productivity at water depths between 12 and 17 m. Measurements were made between November 2015 and September 2016. Dissolved oxygen fluxes were measured using benthic chambers with four different light levels and used to calculate gross primary production and respiration. Phytoplankton productivity was measured using 14 C-uptake incubations in a laboratory photosynthetron. Organic matter production by benthic microalgae is substantial in this region of northeastern Gulf of Mexico with daily production rates ranging from 0.1 to 0.8 g C m −2 d −1 in this study. Maximum rates of phytoplankton production up to 2.7 g C m −2 d −1 occurred in spring. This peak productivity followed wind conditions favorable to upwelling and occurred when bottom water NO3 − concentrations were 11 times greater than on any other sample date during the study. At these shallow depths, benthic microalgae made a significant contribution to total shelf production, averaging about 14% of total production. These results helped characterize benthic and water column production rates prior to planned habitat alterations caused by placement of numerous artificial reef structures in the region. Highlights: The northeastern Gulf of Mexico shallow shelf is a high light environment. This region is influenced by estuaries and upwelling from DeSoto Canyon. Peak phytoplankton production occurred in spring when nitrate concentrations were high. Benthic microalgal biomass was highest in the summer and negatively correlated with light attenuation. Organic matter production by benthic microalgae was substantial, averaging about 14% of total primary production.