CFE agenda 091117 - Laserfiche WebLink

Browse Search

Fig. 3. Breeding and nesting phase of marine turtles. Dotted grey arrows represent the potential climate variables and their indirect effects, + or - indicate likely direction of effect Figure 3 -4. Climatic factors affecting sea turtles during nesting and breeding (Source: Hawkes et al. 2009, © Inter - Research, used with permission). Increases in sand temperature due to climate change may affect reproductive success and hatchling devel- opment, as well as the sex ratios of offspring produced (Hawkes et al. 2009). Marine turtles typically incubate successfully only between 77 and 95T (Ackerman 1997 in Hawkes et al. 1997). In general, the higher end of this temperature range produces female embryos while lower temperatures result in male turtles (e.g., Hays et al. 2003). An equal number of males and females are produced at the `pivotal temperature' which, for loggerhead turtles, occurs between 82.4 to 87.8 °F (Mrosovsky 1988). Projected future increases in temperature could result in biased sex ratios towards females, although behavioral changes, such as choos- ing shaded nesting sites, nesting earlier, or nesting later in the season, could maintain mixed sex ratios (Hawkes et al. 2009). Whether marine turtles will be able to adapt either behaviorally or physiologically to increased temperatures for incubation, remains unclear. Aquatic habitats and species are expected to be signif- icantly impacted by warming climate trends. The Southeast has the highest aquatic species diversity in the entire United States, including significant taxo- nomic diversity of fishes, mollusks, and crayfish (NC WAP). A significant proportion of these groups are already known to be at risk in North Carolina, with 83 fish species, 43 mussel species, 21 crayfish species, and 10 snail species identified as priorities for conser- vation in the NC WAP. Major threats identified in the NC WAP include pollution, hydrologic altera- tion, physical habitat manipulation, and introduc- tion of non - indigenous species, many of which are likely to be exacerbated by climate change. In the Piedmont and Mountains, a number of river basins are already extensively modified by dams (Figure 3 -5) and impoundments, further limiting species ability to move to more suitable habitats under changing climatic conditions. f Photo: Cheoah Dam, www. learnnc. orgld lmultimedi&7836 58 Chapter 3: Projected Impacts of Climate Change in North Carolina