Our analyses under the Act include consideration of ongoing and projected changes in climate. The terms “climate” and “climate change” are defined by the Intergovernmental Panel on Climate Change (IPCC). “Climate” refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (IPCC 2014, p. 557). The term “climate change” thus refers to a change in the mean or variability of one or more measures of climate (e.g., temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both (IPCC 2014, p. 557). Various types of changes in climate can have direct or indirect effects on species. These effects may be positive, neutral, or negative and they may change over time, depending on the species and other relevant considerations, such as the effects of interactions of climate with other variables (e.g., habitat fragmentation).
The likely impacts of climate change on aquatic systems include increases in water temperatures that may alter fundamental ecological processes, thermal suitability of aquatic habitats for prey species, as well as the geographic distribution of species (Poff et al. 2002). Changes and shifts in seasonal patterns of precipitation and runoff will alter the hydrology of stream systems, affecting species composition and ecosystem productivity. Aquatic organisms are sensitive to changes in frequency, duration, and timing of extreme precipitation events such as floods or droughts. Climate change is an additional stressor to sensitive freshwater systems, which are already adversely affected by a variety of human impacts, such as altered hydrological regimes and deterioration of water quality.
Aquatic ecosystems have a limited ability to adapt to climate change. Reducing the likelihood of significant impacts will largely depend on human activities that reduce other sources of ecosystem stress to ultimately enhance adaptive capacity; these include maintaining riparian forests and forested wetlands, reducing nutrient loading, restoring damaged ecosystems, and minimizing groundwater and surface water withdrawal (Poff et al. 2002).
For the Southeastern US, the range of the various models used predicts a 4oF to 8 oF increase in the annual mean temperature, with the coastal regions 1oF to 2oF less than the interior temperatures through 2100 (Carter et al. 2014). Coastal temperatures are often influenced by the winds off of the Atlantic Ocean and the Gulf of Mexico. Precipitation models for the region indicate small changes relative to natural variations due to the Southeast’s transitional location between a much drier southwest and a wetter north. Change is more likely to be in an increase in number of consecutive days without precipitation and an increase in Category 4 and 5 tropical storms intensified by higher temperatures (Carter et al. 2014).
Panama City crayfish was included in a statewide vulnerability assessment for approximately 1000 species in Florida (Reese et al. 2013, Hocter et al. 2014) using Standardized Index of Vulnerability and Value Assessment (SIVVA; Reese and Noss 2014). Briefly, the thirty criteria are distributed across four modules in SIVVA: 1) Vulnerability, 2) Lack of Adaptive Capacity, 3) Conservation Value, and 4) Information Availability. For each species, they solicited experts who authored papers or conducted studies on the species or were directly involved in their management. Experts were given SIVVA in the form of an Excel Worksheet, maps of projections of 0.5, 1.0, 2.0, and 3.0m of sea level rise (SLR), projected changes in temperature and precipitation. Climate changes were based on downscaled global projections for a ‘medium’ (A1B) Emission Scenario (ES), and an Ensemble Average General Circulation Model (GCM) following the IPCC Fourth Assessment. Based on the data through 2012 for PCC in Florida Natural Areas Inventory used in this assessment, PCC did not meet the vulnerability assessment criteria because the initial assessment using a 10 m digital elevation model “bathtub” projection of 2 m SLR indicated less than 50% of its element occurrences were each inundated by less than 50% according to the model.