Ecological Risks in the Caloosahatchee Estuary: A Conceptual Model Developed through the Southwest Florida Feasibility Study Darren Rumbold, Ph. D Professor of Marine Science Depart. of Marine and Ecological Sciences Coastal Watershed Institute Florida Gulf Coast University

Southwest Florida Feasibility Study (SWFFS) Purpose and Relationship to Comprehensive Everglades Restoration Plan (CERP) and Critical Projects The Restudy recommended a separate Comprehensive watershed study for Southwest Florida with the following purposes Health of aquatic ecosystems Water flows Water quality (including appropriate pollution reduction targets) Water supply (Lower West Coast Water Supply Plan) Flood damage reduction Wildlife and biological diversity Natural habitat Recreation (opportunity)

Combined efforts of many individuals in SWFFS subteams

Barnes, 2005 For many resource managers, it can be a struggle determining which of several anthropogenic stressors in a particular system exerts the greatest impacts on the biota in the receiving systems, and selecting appropriate mitigation options. So its important to develop a conceptual model showing the relationships among human activities in the watershed; the physical, chemical, and biological stressors believed to occur as a result of those activities. These are our risk hypotheses. Through a series of meetings with the general public and local and state managers we identified these as major anthropogenic stressors. This situation is not unique to Caloosahatchee --- many estuaries face a plethora of such environmental problems as a consequence of human activities.

Benefits of Developing Conceptual Models? The process of creating a conceptual model is a powerful learning tool. Conceptual models are easily modified as knowledge increases. Conceptual models highlight what is known and not known and can be used to plan future work. Conceptual models can be a powerful communication tool. They provide an explicit expression of the assumptions and understanding of a system for others to evaluate. Conceptual models provide a framework for prediction and are the template for generating more risk hypotheses.

Barnes, 2005 The focus here will be on the stressors Next, Peter will focus on ecological indicators – ecological entity and atribute

Drivers Stressors Sea Level Rise Water Management Land Use & Management Maintaining Navigation Altered Estuarine Salinity Altered Hydrology Input & Elevated Levels of Nutrients, Dissolved Organics & Toxins Boating & Fishing Pressure Physical Alteration to Estuary SWFFS focused on quantity, quality, timing and distribution of inputs

Altered Salinity Regime While estuarine species are generally well adapted to cope with varying salinity conditions, larger shifts and timing of freshwater discharges can be a problem. impacts the community structure and function of phytoplankton, submerged aquatic vegetation (SAV), macroalgae, benthos- particularly oysters and fisheries Secondary, or indirect, effects on manatee demographics and wading bird community structure

Important to Clearly Identify and Communicate Cascading Adverse Effects Primary, or direct, effects: occur when a stressor acts directly on the assessment endpoint and causes an adverse response Secondary, or indirect, effects: occur when the entity’s response becomes a stressor to another entity are often a series of effects among a diversity of organisms and processes that cascade through the ecosystem may have greater ecological significance than primary effect

Increased Nutrients & Contaminants Biostimulants, e.g., inorganic and organic nutrients, influence growth and community structure of phytoplankton, macroalgae, and microbes. Indirect effects on SAV, zooplankton, fish and other aquatic organisms from: 1) light attenuation, 2) altered dissolved oxygen concentrations, and 3) biotoxins which, in turn, can have cascading effects on manatee, dolphins and wading bird community structure

Cloern 2001, Marine Ecology Progress Series

Table 1. Summary of findings of water quality assessments in the Caloosahatchee Estuary, San Carlos Bay, Pine Island Sound and Matlacha Pass. Results of a number of recent water quality assessments of the Caloosahatchee Estuary and Lower Charlotte Harbor showed remarkable agreement Not surprisingly, many of the assessments report WQ issues with a strong longitudinal gradient with most constituents decreasing in concentration with increasing distance from the S79 structure; but different river segments were subject to different stressors; e.g., light attenuation factors change within the Caloosahatchee. And it was NOT just plant nutrients And the stressors and response varied with season. The WQ team assembled the information available at the time– through a subcontract with Tetra Tech…actually we compiled close to 2 million records, to assess current conditions and trends.

Table 1. Continued.

Increased Nutrients & Contaminants Toxicants, both metals and organics (e.g., pesticides, pharmaceuticals and personal care products) could be having insidious effects on individuals (e.g., immunosuppression, behavior, etc.) populations and community structure. Loss or contamination of prey can have indirect effects on fish and wildlife predators (e.g., sharks, dolphins, birds), as well as human consumers

WQ PERFORMANCE MEASURE Input parameters might include: water-column BOD, COD; sediment oxygen demand; adsorption coeff., particle-size distribution, settling coeff.; rates of nitrification, denitrification, mineralization and fixation; reaeration rate (SA/vol., temp., turbulence, stratification, algal growth, photosynthesis, respiration, settling rates; light avail. (note, inter-dependence). WQ PERFORMANCE MEASURE Parameter; causal, response or both Target Component specific WQS; Inflow v. outflow Constraint TSS; Turbidity DOC / DOM; TN (NOx + TKN); TP, SRP Basin e.g., C43, Tidal Caloosahatchee, Estero, and BCB Process model, e.g., ECOlab concentration Historical-based, e.g., natural systems, OFW, etc. loads Loading model Empirical model, e.g., regression concentration loads loads Reference site, e.g., 10K Island, 25th - 75th percentile for a given salinity regime BMP effectiveness as % reduction Process model, e.g., ECOlab Empirical model, e.g., regression concentration Fraction of Freshwater Method, i.e., mass balance Dissolved Oxygen; Chl-a; Color; Clarity / PAR BPJ Figure is very busy – but I want to identify the difficulties that we encountered in the SWFFS There are a number of ways to set restoration targets –unfortunately the target with the most clout – that is likely to receive the most support –based on an eco-resource or valued ecosystem component (VEC) – is also the most difficult to establish. Understandably, resources managers demand assurances that, if they spend $$$ of taxpayers money to remove the stressor, it will result in ecological restoration; they want to see predictive models linking the stressor to the eco-resource. These days Best professional judgment is insufficient. A lot of us in this room know whats wrong and how to fix it but cannot not mathematically demonstrate how much the knobs must be turned back. The SWFFS was constrained to using the data that was available at the time to develop predictive models linking the eco-resource to the stressor –but there was large gaps in the data (plan never included funding research). successful in limited number of instances using Habitat suitability indices – where the strength of association was very large “to altered salinity”. Difficult to link inorganic nutrients …to…spotted seatrout habitat So, in my opinion, that is where we can focus some of our effort –improving the models –and making certain to capture the indirect or cascading effects. Coordinate w/ Natural Systems Group Input parameters will include: Land use Soils Topography Land use-specific event mean conc. Land use-sp. runoff coefficient Many other simplifying assump. HSI model; BPJ Eco-resource, e.g., SAV, oysters, redfish; sawgrass Habitat Units, e.g., acres, lbs, Catch per unit effort Output Scale ??? Instantaneous minimum ---Seasonal means Point - River segment - Spatially explicit NEED TO CONNECT THE DOTs

Simultaneous Effects of Multiple Stressors Cloern 2001, Marine Ecology Progress Series Simultaneous Effects of Multiple Stressors “The presence of multiple stressors may either increase or dampen the temporal and spatial variability seen in aquatic systems, depending on the interactions among stressors and the influence of background environmental conditions and sensitive species on the expression of stressor effects.” (Breitburg et al. 1999)

We know this through manipulative mesocosm-scale experiments, particularly in Chesapeake Bay, that revealed trophic cascading. Breitburg et al. 1999

Barnes, 2005 So I would argue that we could improve and expand this conceptual model

Take Home Message Many people invested an incredible amount of time and energy in the SWFFS developing decision-support products such as the conceptual model Although those products should serve as a strong foundation, they can be improved upon and expanded, especially the predictive models linking stressors with eco-resources We are not under the same constraints as SWFFS and so can develop an analysis plan for research to fill data gaps, particularly on simultaneous effects of multiple stressors and indirect effects