Chenoweth Kelsey

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Last Name
Chenoweth
First Name
Kelsey
ORCID
0000-0002-8748-0208

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  • Article
    Stable isotopic evidence of nitrogen sources and C4 metabolism driving the world’s largest macroalgal green tides in the Yellow Sea
    (Nature Publishing Group, 2018-11-28) Valiela, Ivan ; Liu, Dongyan ; Lloret, Javier ; Chenoweth, Kelsey ; Hanacek, Daniella
    During recent years, rapid seasonal growth of macroalgae covered extensive areas within the Yellow Sea, developing the world’s most spatially extensive “green tide”. The remarkably fast accumulation of macroalgal biomass is the joint result of high nitrogen supplies in Yellow Sea waters, plus ability of the macroalgae to optionally use C4 photosynthetic pathways that facilitate rapid growth. Stable isotopic evidence shows that the high nitrogen supply is derived from anthropogenic sources, conveyed from watersheds via river discharges, and by direct atmospheric deposition. Wastewater and manures supply about half the nitrogen used by the macroalgae, fertiliser and atmospheric deposition each furnish about a quarter of the nitrogen in macroalgae. The massive green tides affecting the Yellow Sea are likely to increase, with significant current and future environmental and human consequences. Addressing these changing trajectories will demand concerted investment in new basic and applied research as the basis for developing management policies.
  • Article
    An example of accelerated changes in current and future ecosystem trajectories: unexpected rapid transitions in salt marsh vegetation forced by sea level rise
    (Elsevier, 2024-01-13) Valiela, Ivan ; Lloret, Javier ; Chenoweth, Kelsey ; Wang, Yuyang
    Accelerated sea level rise has forced greater changes in the vegetation of Great Sippewissett Marsh during the recent few years than were recorded in the previous half century. Even with conservative estimates of sea level rise, accretion in the salt marsh platform would be insufficient to match submergence, but in addition, a new set of cascading changes seem to be accelerating the transformation of the Great Sippewissett Marsh vegetation mosaic, including conversion of cover by short to taller Spartina alterniflora, leading to lowering below-ground biomass and weakening of sediment columns, while the greater above-ground biomass increases wrack that strands and smothers high marsh vegetation. In addition, a salt-tolerant variant of Phragmites australis has begun to aggressively invade upper elevations of Great Sippewissett Marsh, replacing high marsh species cover, as well as dominating adjoining low-lying areas that might have allowed salt marsh landward migration as sea level effects increase. In many parts of Great Sippewissett Marsh, area of high marsh is steadily diminishing, taller S. alterniflora has extended upwards in areas previously supporting high marsh species, but its landward progress is now impeded by competition and shading by the phalanx of P. australis that has extended down-slope. The vegetation gradient in Great Sippewissett Marsh—and other salt marshes—is in rapid transition, and its decadal future seems in doubt.