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Title: Net heterotrophy and carbonate dissolution in two subtropical seagrass meadows
Abstract. The net ecosystem productivity (NEP) of two seagrassmeadows within one of the largest seagrass ecosystems in the world, FloridaBay, was assessed using direct measurements over consecutive diel cyclesduring a short study in the fall of 2018. We report significant differencesbetween NEP determined by dissolved inorganic carbon (NEPDIC) and bydissolved oxygen (NEPDO), likely driven by differences in air–water gasexchange and contrasting responses to variations in light intensity. We alsoacknowledge the impact of advective exchange on metabolic calculations ofNEP and net ecosystem calcification (NEC) using the “open-water” approachand attempt to quantify this effect. In this first direct determination ofNEPDIC in seagrass, we found that both seagrass ecosystems were netheterotrophic, on average, despite large differences in seagrass netabove-ground primary productivity. NEC was also negative, indicating thatboth sites were net dissolving carbonate minerals. We suggest that acombination of carbonate dissolution and respiration in sediments exceededseagrass primary production and calcification, supporting our negative NEPand NEC measurements. However, given the limited spatial (two sites) andtemporal (8 d) extent of this study, our results may not berepresentative of Florida Bay as a whole and may be season-specific. Theresults of this study highlight the need for better temporal resolution,accurate carbonate chemistry accounting, and an improved understanding ofphysical mixing processes in future seagrass metabolism studies.  more » « less
Award ID(s):
1832229 1237517
NSF-PAR ID:
10138745
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Biogeosciences
Volume:
16
Issue:
22
ISSN:
1726-4189
Page Range / eLocation ID:
4411 to 4428
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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