2020 South Florida Environmental Report – Volume I Chapter 6 1 Chapter 6: 2 Everglades Research and Evaluation 3 Edited by Fred Sklar 4 SUMMARY 5 This chapter summarizes Water Year 2019 (WY2019; May 1, 2018–April 30, 2019) hydrology in the 6 Everglades Protection Area (EPA), followed by an overview of key Everglades studies on wildlife, plants, 7 the ecosystem, and landscapes (Table 6-1). Programs of study are based on the short-term operational needs 8 and long-term restoration goals of the South Florida Water Management District (SFWMD or District), 9 including large-scale and regional hydrologic needs in relation to regulation schedules, permitting, 10 Everglades Forever Act (Section 373.4592, Florida Statutes [F.S.]) mandates, and the Comprehensive 11 Everglades Restoration Plan (CERP). In addition, the Decomp Physical Model (DPM) research is discussed 12 in Appendix 6-1 of this volume. 13 Table 6-1. WY2019 Everglades research findings in relation to operational mandates. Hydrology Projects Findings Mandates a Across most of the Everglades, water depths began WY2019 just below average historic stages. Well above average late dry season rainfall raised stages quickly and depths peaked earlier than normal. Most areas within the Everglades Water Conservation Areas (WCAs) fell below average depths by the ROS Hydrologic Patterns for WY2019 end of the wet season. Dry season depths and recession rates MFL in the WCAs were largely not conducive for optimal wading bird foraging. The stage and recession rate in Everglades National Park (ENP) were closer to optimal, and higher numbers of nesting wading birds were noted there. After beginning WY2019 with above average flows and below average salinities, low rainfall through the WY2019 wet season CERP led to salinity increases that continued through the dry season. MFL Florida Bay Hydrology Eastern and central Florida Bay ended WY2019 with above average salinities. Western Florida Bay salinities did not rise as ROS quickly in the dry season and ended WY2019 slightly below COP average. 14 DRAFT 6-1 10/25/2019 2020 South Florida Environmental Report – Volume I Chapter 6 15 Table 6-1. Continued. Wildlife Ecology Projects Findings Mandates a Wading bird nesting effort and success was relatively reduced in in the Everglades during WY2019. An estimated 32,165 wading bird nests were initiated. This effort represents three-quarters of CERP the decadal average nest count and only a quarter of the CEPP number recorded last year. All indicator species, with the Wading Bird Monitoring COP exception of the snowy egret, exhibited decreased nesting effort during 2019. Of note was the complete failure of nesting by the EFA federally threatened wood stork (no chicks fledged from ROS 970 nests). Low stages at the start of the breeding season followed by rain-driven reversals led to poor prey availability Excess salt in marine invertebrates impose a physiologic burden on developing white ibis chicks, which helps to explain some of the reduced breeding activity in the coastal mangroves. CERP Irruption of Ibis Nesting in However, the Calendar Year 2018 (CY2018) ibis nesting activity CEPP Association with Crayfish Foraging in the coastal colonies was more than 25-fold higher than in COP in the Southern Everglades CY2017 and was the highest reported for the region in at least EFA 80 years. An analysis of the gut content of the chicks indicated ROS that freshwater prey, especially crayfish provided the key trigger for high nesting activity in the coastal colonies of ENP. Plant Ecology Projects Findings Mandates a Growth Response of Florida Native The preservation of the plant community dynamics on tree CERP Trees to Hydrology on Two islands, including the natural shifts in species composition, forest CEPP Constructed Everglades’ Tree structure, aboveground production and tree growth are directly COP Islands in the Loxahatchee dependent on the existence of a mosaic of hydrological Impoundment Landscape conditions, and the promotion of a strong wet and dry cycle EFA Assessment (LILA) throughout the Everglades ecosystem. ROS Continued recovery from the 2015 seagrass die-off event has CERP been occurring, but recent water quality conditions as a result of MFL Florida Bay Benthic Vegetation disturbances, such as storms, may be slowing the recovery of ROS the seagrass community. COP Ecosystem Ecology Projects Findings Mandates a The AMI approach changed the physical characteristics of the landscape and created sloughs with connectivity similar to that observed historically. As of CY2019, 2 years after treatment, the CERP Active Marsh Improvement (AMI) in AMI sloughs are still open and slough vegetation species CEPP the Decomp Physical Model (DPM) (Utricularia sp., periphyton, water lilies) are expanding within the EFA treatment area. The success of this landscape level adaptive ROS management suggests that we have the potential to restore flow direction and velocities in degraded areas of the Everglades. Tropical Storm Gordon and Hurricane Michael impacted the water quality in Florida Bay. With the exception of chlorophyll a (Chla) and total phosphorus (TP) in the eastern region, WY2019 CERP results were elevated above the Florida Administrative Code Florida Bay Water Quality CEPP (F.A.C.) basin standards. Chla and TP in all three regions of the and Status bay elevated in WY2018, decreased back to WY2017 levels, but MFL were still elevated above the period of record (POR) averages in ROS the central and western regions. Total nitrogen (TN) has been slightly elevated in all three regions of the bay since WY2016. 16 DRAFT 6-2 10/25/2019 2020 South Florida Environmental Report – Volume I Chapter 6 17 Table 6-1. Continued. Ecosystem Ecology (continued) Projects Findings Mandates a Because we are documenting trends over time, it is important to document and understand the causes for any abrupt and/or unexpected changes in the long-term POR. An approximately CERP Total Nitrogen in the Florida Bay 30% increase in TN in Florida Bay was observed in CY2009, the MFL Water Quality Monitoring Network time of an analytical lab change. Results could not conclusively demonstrate that the CY2009 unexpected change in TN was ROS due to a difference in analytical methodology, however evidence against this is presented. The Upper Taylor Slough area is a unique short hydroperiod marsh that may experience shifts in community composition with CERP Upper Taylor Slough increased westward flow through the S-332s and S-200 MFL Adaptive Management structures. Community compositions have been documented as a baseline from which to compare as increased water deliveries ROS continue to Taylor Slough in future years. Landscape Ecology Projects Findings Mandates a Despite large-scale disturbance, Florida Bay exhibited resilience. Algal blooms that began in October 2017 (WY2018) subsided across the bay by June 2018 (WY2019). Elevated Chla CERP Synoptic Ecological returned in October following Tropical Storm Gordon and MFL Mapping in Florida Bay Hurricane Michael, forming algal bloom Hot Spots; however, ROS Chla concentrations were lower than those following Hurricane Irma and dissipated within 4 months. Decomp Physical Model Research (Appendix 6-1) Projects Findings Mandates a Despite inflow TP concentrations at or below 10 parts per billion CERP (ppb), accelerated flows at sites closest to the S-152/Decomp CEPP Evaluating Food Web and Sediment Physical Model (DPM) structure increased local TP loads. Local EFA Nutrient Responses to Flow: TP loading rates of approximately 10 to 25 grams per meter per Periphytic Community Response day downstream of the DPM structure, are associated with floc FEIM and periphyton biomass with TP content above 500 milligrams ROS per kilogram; a concentration indicative of nutrient enrichment. The enrichment of sediments downstream of the L-67C levee gap, particularly the unfilled canal treatment, suggests that sediment dynamics in canals that are not backfilled may impact CERP the process of sediment phosphorus (P) enrichment. The CEPP Evaluating Food Web and Sediment highest loading rates observed in this study (25 g/m/d) are within EFA Nutrient Responses to Flow: the range of moderately enriched (11.3 g/m/d) and highly Sediment Chemistry Changes enriched (27.9 g/m/d) cattail habitats, in which high P loads FEIM reflected high water column TP rather than high velocity. Flow ROS restoration targets should consider an envelope of flow and loading conditions that maximize ecosystem benefits and minimize ecological costs. 18 DRAFT 6-3 10/25/2019 2020 South Florida Environmental Report – Volume I Chapter 6 19 Table 6-1. Continued. Decomp Physical Model Research (continued) Projects Findings Mandates a An important objective of DPM is to test how levee gap design and the degree of backfill (no backfill, partial backfill, and complete backfill) influence sheetflow and conveyance of sediment and P. Backfill treatments differed in the degree to CERP which they passively conveyed constituents; however, the causal factors for differential “processing” of constituents is CEPP Water and Constituent Fluxes unfortunately confounded with the uneven distribution of fluxes EFA through the L-67C Levee Gap entering the three treatment areas and the non-uniform FEIM contributions from canal inflows and wetland sheetflow. ROS Nonetheless, there was clear evidence that the unblocked extensions of L67-C canal dominated water and constituent throughput in the levee gap that disrupted and diminished wetland-to-wetland connectivity by sheetflow that is the desired outcome of removing levees. a. Mandates CEPP Central Everglades Planning Project CERP Comprehensive Everglades Restoration Plan COP Combined Operations Plan EFA Everglades Forever Act, Section 373.4592, F.S. FEIM Florida Everglades Improvement and Management LTP Long-Term Plan for Achieving Water Quality Goals in the Everglades Protection Area MFL Minimum Flows and Minimum Water Levels, Section 373.042, F.S., and Chapter 40E-8, F.A.C. ROS Regulation and Operational Schedules RS Restoration Strategies 20 21 HYDROLOGY 22 WY2019 water depths in the Everglades began the season very near average historic stages.