Variation in benthic metabolism and nitrogen cycling across clam aquaculture sites. (February 2018)

• Record Type: Journal Article
• Authors: Murphy, Anna E.; Nizzoli, Daniele; Bartoli, Marco; Smyth, Ashley R.; Castaldelli, Giuseppe; Anderson, Iris C.
• Is Part Of: Marine pollution bulletin. Volume 127(2018)
• Page Start: 524
• Page End: 535
• Publication Date: 2018-02
• Subjects: Denitrification -- DNRA -- Nitrification -- Nitrate respiration -- Clam aquaculture -- Nitrogen cycling; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2017.12.003
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: As bivalve aquaculture expands globally, an understanding of how it alters nitrogen is important to minimize impacts. This study investigated nitrogen cycling associated with clam aquaculture in the Sacca di Goro, Italy ( Ruditapes philipinarum ) and the Eastern Shore, USA ( Mercenaria mercenaria ). Ammonium and dissolved oxygen fluxes were positively correlated with clam biomass; R. philippinarum consumed ~ 6 times more oxygen and excreted ~ 5 times more NH4 + than M. mercenaria . There was no direct effect of clams on denitrification or dissimilatory nitrate reduction to ammonium (DNRA); rather, nitrate availability controlled the competition between these microbial pathways. Highest denitrification rates were measured at sites where both water column nitrate and nitrification were elevated due to high densities of a burrowing amphipod ( Corophium sp.). DNRA exceeded denitrification where water column nitrate was low and nitrification was suppressed in highly reduced sediment, potentially due to low hydrologic flow and high clam densities. Highlights: Clam aquaculture promotes nitrogen recycling while removal depends on environment. Clams directly affected dissolved oxygen and ammonium with species differences. Clams did not directly affect denitrification or DNRA; nitrate supply was important. High nitrate supply, due to bioturbating infauna, favored denitrification over DNRA. Environmental context should be considered when assessing N mitigation by bivalves.