Climate Change Projected Effects on Coastal Foundation Communities of the Greater Everglades Using a 2060 Scenario: Need for a New Management Paradigm

Abstract

Rising sea levels and temperature will be dominant drivers of coastal Everglades' foundation communities (i.e., mangrove forests, seagrass/macroalgae, and coral reefs) by 2060 based on a climate change scenario of +1.5 °C temperature, +1.5 foot (46 cm) in sea level, ±10 % in precipitation and 490 ppm CO2. Current mangrove forest soil elevation change in South Florida ranges from 0.9 to 2.5 mm year(-1) and would have to increase twofold to fourfold in order to accommodate a 2060 sea level rise rate. No evidence is available to indicate that coastal mangroves from South Florida and the wider Caribbean can keep pace with a rapid rate of sea level rise. Thus, particles and nutrients from destabilized coastlines could be mobilized and impact benthic habitats of southern Florida. Uncertainties in regional geomorphology and coastal current changes under higher sea levels make this prediction tentative without further research. The 2060 higher temperature scenario would compromise Florida's coral reefs that are already degraded. We suggest that a new paradigm is needed for resource management under climate change that manages coastlines for resilience to marine transgression and promotes active ecosystem management. In the case of the Everglades, greater freshwater flows could maximize mangrove peat accumulation, stabilize coastlines, and limit saltwater intrusion, while specific coral species may require propagation. Further, we suggest that regional climate drivers and oceanographic processes be incorporated into Everglades and South Florida management plans, as they are likely to impact coastal ecosystems, interior freshwater wetlands and urban coastlines over the next few decades.

The effects of CO2 and nutrient fertilisation on the growth and temperature response of the mangrove Avicennia germinans

“…Based on theoretical models of photosynthesis, elevated CO 2 concentrations could have a strong effect on the temperature response of photosynthesis (Farquhar et al 1980;Lloyd and Farquhar 2008), but experimental evidence for this is not well documented for tropical trees. A number of recent models predict a significant shift in mangrove distributions, for example the loss of mangrove forests from regions of high temperature and a reduction in productivity based on an anticipated rise in global temperature (Beaumont et al 2011;Osland et al 2013;Koch et al 2015), but these predictions are based on the climatic niche of the presentday mangroves growing under current CO 2 concentrations. The scarcity of experiments testing how elevated CO 2 affects the temperature relationships of tropical trees hinders our ability to model how elevated CO 2 will affect primary productivity in these systems into the future (Cernusak et al 2013).…”

Niche partitioning of intertidal seagrasses: evidence of the influence of substrate temperature

“…There are clear concerns within the literature that increases in water temperature and extreme heat events (air temperature) will influence seagrass survival (e.g. Jordà et al ., ; Collier & Waycott, ; Koch et al ., ; Thomson et al ., ; Pedersen et al ., ; Galli et al ., ). Furthermore, our results demonstrate that intertidal seagrasses occupy species’ specific soil temperature envelopes, with H. uninervis actively using the soil temperature gradients to reduce temperature fluctuations based on depth of below‐ground biomass.…”

Hurricane storm surge in Volusia County, Florida: evidence of a tipping point for infrastructure damage

“…In the Florida Everglades, flooding risk is higher than one might expect based solely on sea-level rise, owing to its inability to handle even routine flooding after climate change (Michener et al, 1997;Koch et al, 2015). Sea-level rise and a variation in storm frequency and timing, for instance, can hinder the ecosystem services provided by coastal wetlands.…”