Science Supporting Management of Eutrophication: Lessons Learned from a Barrier Island Lagoon

For decades, the Indian River Lagoon, an Estuary of National Significance, has been impaired by excessive loads of nitrogen and phosphorus. While addressing this impairment, conditions changed dramatically. A “superbloom” of phytoplankton generated concentrations of chlorophyll-a that were ~2x higher than 99% of the values recorded in a 15-year period of record (over 100 µg/L), and concentrations > 30 µg/L persisted for 5 -7 months rather than ≤ 3 months. Subsequent blooms of brown tide and mixed phytoplankters yielded concentrations of chlorophyll-a up to 200 µg/L and concentrations > 30 µg/L for 11 -13 months. Seagrass, the chosen indicator of ecosystem health, had been expanding, but its footprint was reduced by over 50% when the light regime was degraded by repeated blooms. A series of studies elucidated factors that initiated and sustained the superbloom, evaluated its ecological effects, tracked subsequent blooms, and explored the possibility of a regime shift.

This Research Topic strives to improve the translation of science into management by synthesizing key results and generating lessons for managers and scientists concerned about eutrophication of estuaries. The topic documents a legacy of impairment similar to many estuaries. It deals with an estuary near one end of the spectrum, with long residence times, tight benthic-pelagic coupling, and multiple pathways for nutrient loading making it diverse, productive, and vulnerable. Lessons for managers and scientists include the need to retain a focus on nutrients leading to increased concentrations of chlorophyll-a, the importance of cycling of nutrients, the value in providing scope for events that deviate from average conditions, the effects of internal loads of nutrients from fine sediments and groundwater, the role of drift algae in cycling of nutrients, how the physiology of key phytoplankton can determine responses to nitrogen to phosphorus ratios and ratios of organic to inorganic nutrients, and the logistics involved in sustainable, large-scale restoration of seagrasses and filter feeders to promote recovery of the system.

Themes to be addressed in this Research Topic include a description of the Indian River Lagoon as an example of a vulnerable estuary; a history of anthropogenic activities and natural events; documentation of the quantity and composition of external, internal, and legacy loads to the system; spatiotemporal trends in phytoplankton, seagrasses, and drift macroalgae, the key primary producers; bottom-up and top-down controls of blooms including characteristics of key species of phytoplankton that obviate those controls; flow-on effects of multiple harmful algal blooms; causes of the initial and subsequent harmful algal blooms; evaluation of the likely future for the lagoon; and lessons learned regarding effective management of eutrophication in a vulnerable system and the science needed to support it.

Authors of Type-A articles accepted for publication can request to have publication costs partially discounted by the Indian River Lagoon (IRL) Council, which is serving as a sponsor of the Research Topic. Questions and requests related to publications costs should be submitted to Charles Jacoby (cjacoby@sjrwmd.com).
This Research Topic is editorially independent of the IRL Council and follows the usual peer-review standards and procedures of Frontiers in Marine Science.

The Topic Editors Charles Jacoby, Edward Phlips, Kevin Johnson, Dennis Hanisak, Duane De Freese and Valerie Paul declare that they have collaborated on projects addressing the Indian River Lagoon and hereby confirm their objectivity.