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Seagrass restoration reestablishes the coastal nitrogen filter through enhanced burial
Author(s) -
Aoki Lillian R.,
McGlathery Karen J.,
Oreska Matthew P. J.
Publication year - 2020
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.11241
Subject(s) - seagrass , zostera marina , zostera , environmental science , ecosystem , temperate climate , biomass (ecology) , sink (geography) , ecology , denitrification , oceanography , nutrient , nitrogen , biology , geology , chemistry , geography , cartography , organic chemistry
Seagrass meadows perform an important ecological function as filters for incoming nutrients from surrounding watersheds, especially nitrogen (N). By enhancing N removal processes, including N burial in sediments and denitrification, seagrass meadows improve water quality. With accelerating losses of seagrass meadows worldwide, seagrass restoration plays a key role in reestablishing these coastal ecosystem functions. However, few measurements exist of N burial rates in temperate seagrass meadows and none have been published for restored meadows. In this study, we measured N burial rates in a large (6.9 km 2 ) restored eelgrass ( Zostera marina ) meadow and compared N removal through burial to previous measurements of removal via denitrification. We also compared N removal to inputs from external loading and fixation and to N assimilation in seagrass biomass. We found that, in this meadow, burial was the dominant process of N removal; the burial rate of 3.52 g N m −2 yr −1 was comparable to rates in natural meadows within 10 yr after seeding and was more than 20× the rate in adjacent bare sediments (0.17 g N m −2 yr −1 ). We also found that the high rates of N assimilation (2.62 g N m −2 yr −1 ) created a substantial though temporary sink for nitrogen during the growing season. Our results highlight how seagrass meadows mediate N cycling through high rates of burial, which to date has been understudied in the literature. The successful return of the N filter function after restoration, shown here for the first time, can motivate continued efforts for seagrass restoration and conservation.