BRS John Kominoski: Shifting freshwater hydrology and saltwater intrusion characterize changing dissolved organic matter along coastal wetland gradients

Share link: https://ubc.zoom.us/rec/share/iNq5jH15igtKZeLJJs6OzWBrj4ZENS37AtlSVS89OCAicFukSNkxKu8Z9qCz_WnH.HH82VBwV2wRIcU9Y

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host: John Richardson

Title talk: Shifting freshwater hydrology and saltwater intrusion characterize changing dissolved organic matter along coastal wetland gradients

Abstract: Coastal wetlands are globally important stores of carbon (C), but rapid climate- and human-driven changes in fresh and marine water are affecting C cycling and storage capacity. The Florida Everglades is a model system to test how water management and rapid sea-level rise are changing C cycling along freshwater-to-marine gradients across diverse ecosystems that include peat and marl marshes, mangroves, and seagrass meadows. Upstream restoration of peat and marls marshes is increasing water depths and methane fluxes. Particulate organic matter nutrients increase and C decrease with water depths that elevate microbial respiration rates in marl but not peat marshes. Saltwater intrusion increases particulate organic C loss through elevated electron acceptors and limiting nutrients that prime microbial breakdown. Landscape-scale shifts in dissolved organic C concentrations and dissolved organic matter (DOM) composition illustrate how shifts in fresh and marine hydrology control lateral fluxes and sources of C. Upstream restoration in peat drainages is increasing marsh C in downstream mangrove estuaries. Saltwater intrusion from sea-level rise is increasing marine and mangrove C and shifting both inland in marl drainages, while upstream restoration in marl marshes is increasing humic DOM from allochthonous peat marshes. Carbonate seagrasses are net sources of atmospheric C despite being net autotrophic ecosystems. As climate and human changes continue to transform coastal ecosystems, integrated approaches to conservation that maximize C storage is critical.

Affiliation: Institute of Environment & Department of Biological Sciences, Florida International University, Miami, USA

Short biography: John Kominoski is a Professor in the Institute of Environment and Department of Biological Sciences at Florida International University. He is the Lead Principal Investigator of the Florida Coastal Everglades Long Term Ecological Research program, which is funded by the National Science Foundation (NSF). His research focuses on biogeochemistry and ecosystem ecology, especially on organic matter processing and the dynamic role of disturbances on spatiotemporal patterns of carbon and nutrients in coastal ecosystems. John's research spans streams, wetlands, and coastal marshes and mangroves. He has conducted research for over 10 years in the Florida Everglades. John collaborates broadly and incorporates both ecological theory and application in his research. He is co-leading an NSF-funded Research Coordination Network called "Hurricane Ecosystem Response Synthesis" that compares storm characteristics and ecosystem responses across subtropical and tropical ecosystems. John has published more than 125 peer-reviewed articles, been awarded grants that have totaled over $20 million, and advised 10 Ph.D. and M.S. students. In 2024, he was honored as a Sustaining Fellow by the Association for the Sciences of Limnology and Oceanography for his advances to aquatic ecology. In 2025, John was awarded a Fulbright Canada Research Chair in Environmental Studies.