Agents of change and temporal nutrient dynamics in the Altamaha River Watershed
Date
2017-01-23
Journal Title
Journal ISSN
Volume Title
Publisher
Ecological Society of America
Abstract
Nutrient and carbon dynamics in river ecosystems are shifting, and climate change is likely a
driving factor; however, some previous studies indicate anthropogenic modification of natural resources
may supersede the effects of climate. To understand temporal changes in river ecosystems, consideration
of how these agents act independently and collectively to affect watershed biogeochemistry is necessary.
Through the Georgia Coastal Ecosystems Long-Term
Ecological Research Project, we assessed nutrient
(phosphorus, nitrogen, silicate) and carbon dynamics, with specific regard to import and export,
in the Altamaha River Basin from 2000 to 2012. This is the first study in the region to document the
biogeochemical patterns in the Altamaha’s four main tributaries, the Little Ocmulgee, Ocmulgee, Oconee,
and Ohoopee rivers, and the relationships between biogeochemistry and historical precipitation and
discharge patterns as well as agricultural and population census data. As discharge patterns are a primary
driver of nutrient loads, we determined that water use was a dominant factor in the shifting ecosystem
dynamics. Dissolved inorganic nitrogen loads were primarily driven by population density and dissolved
inorganic phosphorus loads were strongly influenced by livestock biomass. Taken together, we conclude
that both the transportation and biogeochemical cycling of nutrients within the Altamaha River Watershed
were highly impacted by anthropogenic influences, which were then further exacerbated by continued
climate change. Furthermore, the N-and
P-loads
in the Altamaha River and tributaries were dominated
by dissolved organic nitrogen and dissolved organic phosphorus, emphasizing a need to further study the
bioavailability of these species and the mechanisms driving their potential ecological impacts.
Description
Publisher's PDF
Keywords
Citation
Takagi, K. K., K. S. Hunter, W.-J. Cai, and S. B. Joye. 2017. Agents of change and temporal nutrient dynamics in the Altamaha River Watershed. Ecosphere 8(1):e01519. 10.1002/ecs2.1519