This project links water balance and carbon budgets to Ecosystem Function and Services (EF&S) in a mangrove estuary while developing strategies for integrating this science into decision-making forums for allocating regional water resources. The study area is the largest mangrove forest in North America, which is located within Everglades National Park (ENP). The project's goals are being accomplished through two open workshops and a focused field experiment. The project leverages ongoing work by the Florida Coastal Everglades Long Term Ecological Research program (FCE-LTER) and other programs associated with Everglades restoration.
The first open workshop is devoted to evaluating linkages between mangrove carbon and water budgets, the ecosystem services provided by the estuary, and the economic value of these services. This workshop brings together a diverse set of experts in water resources engineering, climatology, mangrove estuary hydrodynamics, carbon cycling, fish behavioral ecology, recreational fisheries, and Everglades restoration. Workshop participants identify research needed to assess changes in mangrove EF&S caused by altered freshwater discharge, sea level rise, and climate variability. Break-out sessions are focused on developing a better understanding of 1) the economic value of the ecosystem services, in part related to Carbon sequestration capacity and 2) linkages between freshwater inputs and the economic value of recreational fishing in ENP using a 30+ year record of fishing practices.
The focused field experiment will investigate linkages between water and carbon cycles. In this experiment, a tracer is followed downstream through several tidal cycles. Samples from within the labeled water plume are collected to measure concentrations and Carbon-13 to Carbon-12 ratios of dissolved organic and inorganic Carbon. The chemical and isotopic composition and molecular structures of the dissolved compounds are used to differentiate between freshwater and marine carbon sources. Isotope approaches are also used to delineate fish foraging behavior along the fresh/saltwater transition zone. In this mangrove forest, eddy covariance estimates of net ecosystem-atmosphere exchange of water vapor and carbon dioxide have been made since 2004 and provide important constraints on the ecosystem water and carbon budgets.
The second open workshop focuses on developing an empirical and methodological framework to assess changes in EF&S and on integrating the results into resource management and restoration cost/benefit analyses. Specific focus is placed on understanding how intangible personal or societal values may influence decision-making more than cost-benefit analyses. Thus, the second workshop has a broader scope in both participant expertise and discussion points than the first.
Improved understanding of water balance and carbon budgets in tropical mangrove estuarine systems and their dependence on management, climate change, and sea level rise can help protect mangrove forests and ensure the continuation of EF&S they provide, including carbon sequestration, fisheries support, storm protection, water purification, and recreation. Tangible economic and less tangible personal or societal values placed on these services are being considered to determine the appropriate management strategies and responses to ecological stressors associated with, for example, a changing climate. Thus, this project represents a first step toward integrating a comprehensive evaluation of mangrove EF&S into the regional water resource management plan affecting the six million inhabitants and unique ecosystems of south Florida which, because of its low-lying topography and extensive coastal wetlands, faces significant risks from sea level rise. This framework can serve as a model for managing estuaries throughout the tropics, with far-ranging implications.
Minority graduate students are being recruited from within Florida International University and other minority-serving institutions to participate in this study. Junior investigators are invited to participate and assume leadership roles in the workshops. Outcomes from the project are broadly disseminated through presentations at various venues, including civic and environmental organizations and government agencies.
This WSC Category 1 Award focused on the effects of managed water inflows on ecosystem services in the Everglades National Park area of Southwestern Florida. The award fostered collaboration among members of a new interdisciplinary team that included atmospheric scientists, biologists, chemists, economists, and hydrologists. The collaboration benefits society by advancing understanding of ecosystem services valuation, advancing knowledge in each of the represented disciplines, and building a foundation for interdisciplinary work. The award also supported the research of several graduate students leading to a Master's thesis. Workshop The award enabled the project team to convene a major workshop that engaged South Florida water managers, a broad range of experts, and stakeholders in discussions on water management and its linkage to ecosystem services (Fig 1). About 50 individuals participated and were provided background information on economic valuation strategies, hydrology, mangrove ecology, carbon cycling, and fisheries. Breakout groups considered specific ecosystem services, data needs, and linkages with human management of the hydrologic system. Finally, a panel discussion led by key economists, managers, and scientists summarized workshop conclusions and provided recommendations to expand the research scope that were incorporated into the project team's successful WSC Category 2 proposal. Data Collection and Valuation of Ecosystem Services Data on ecosystem services including fisheries and carbon behavior in mangrove forests were collected and valuations of some ecosystem services were developed. Fisheries Recreational fisheries are a key ecosystem service provided by mangrove areas of the Everglades. Over 50,000 recreational fishing trips are estimated to take place annually in coastal Everglades National Park, with 120-400 recreational vessels per day. A Bonefish and Tarpon Trust survey showed that 21% of Florida anglers fished in the Everglades region, generating $1.2 billion in annual economic activity. Our sampling shows that abundance and distribution of key recreational species is strongly influenced by marsh hydrology, which depends on South Florida's seasonal rainfall patterns and on water management when water shortages route water elsewhere. Our electrofishing data showed that the upper Shark River estuary — the main Everglades drainage — has a diverse and dynamic fish community composed of transient marsh fish, resident estuarine fish, and transient marine fish (Fig. 2). Sampling shows that fish type and abundance in the upper Shark River varies by season in response to marsh hydrological conditions. Our sampling indicates marsh drying is a major determinant of the fish community in the marsh-mangrove transition area. Marsh drying results in pulses of prey in the mangroves that are consumed by freshwater fish and by estuarine fish that move up the estuary to capitalize on high prey numbers. This variability in ecosystem function with water availability provides a link between water management and the Estuary's recreational fisheries ecosystem service. Carbon The emergence of carbon markets generates interest in carbon stored in forest ecosystems. The economic value of forest carbon arises because CO2, a major greenhouse gas, is locked up in forest ecosystems. This project has collected detailed data on carbon sources, transport, and fate in the Shark River mangrove forest — the largest in North America — with the objective of understanding the carbon balance in this tidally-influenced environment (Fig 3). Multiple approaches have been used for valuing carbon storage ecosystem services in the past. Determining the best method for arriving at a scientifically-justified and socially-acceptable price range for mangrove forest carbon storage requires analysis of alternative valuation methods. Three different approaches were considered in our work: a) social costs of carbon that estimate damages from increasing carbon emissions including changes in agricultural productivity, human health, property damages from increased flood risk, and the value of ecosystem services due to climate change determined by the 2010 US Interagency Working Group on Social Cost of Carbon; b) marginal abatement costs representing options available to an economy to reduce pollution from power, industry, waste, buildings, transport, agriculture, and forestry; and c) regulatory and voluntary market prices. The prices and costs of carbon storage vary widely across countries, markets, and types of storage. Technological, regulatory, economic, and social factors influence its prices. It is not obvious which price would be relevant to value carbon storage in Everglades mangroves. Because there is no established market in the US, no reliable market prices are available. Consequently, more reliable estimates would be obtained from costs of damage avoidance or costs of damage approaches. In addition to estimating carbon price ranges, we created an inventory of above- and below-ground mangrove carbon that is used with prices to estimate total value. Marginal abatement costs yield the highest estimates for Everglades mangrove carbon storage with an average value of $6 billion. Social cost estimates average $3 billion. Market prices average $1.6 billion. Average value per hectare of Everglades mangroves is $47,000 for marginal abatement costs, $23,000 for social cost, and $13,000 at market prices.
