Effect of tidal overwash on the embryonic development of leatherback turtles in French Guiana

Abstract

a b s t r a c tIn marine turtles, the physical conditions experienced by eggs during incubation affect embryonic development. In the leatherback, hatching success is known to be low in relation to other marine turtles as a result of high embryonic mortality. Moreover, the hatching success on Yalimapo in French Guiana, one major nesting beach for this species, is lower compared to other nesting sites. We assessed the rate of leatherback turtle embryonic mortality in order to investigate the tolerance of leatherback turtle clutches laid on Yalimapo beach to tidal overwash, and we highlight causes of poor hatching success. Of the 89 nests studied, 27 were overlapped by tide at least once during the incubation period (of which five nests were lost by erosion). The hatching success was on average significantly lower in overwashed nests than in non-overwashed, highlighting the existence of embryonic developmental arrest linked to tidal inundation. The stages of developmental arrest and their proportion are linked with time, frequency and level of overwash events. In the context of global warming and associated sea-level rise, understanding the detrimental effect of tidal inundation on the development of marine turtle nests is of interest in nesting sites where turtles are likely to be forced to nest closer to the tide line, thus exposing their nests to greater risk of nest overlap with sea and tidal inundation.

Nest inundation from sea-level rise threatens sea turtle population viability

“…Habitat availability therefore constrains nest placement, and this can render nests in even the most elevated positions vulnerable to inundation [3,12]. Short periods of saltwater inundation, such as those associated with high tides during severe storms, substantially lower green turtle egg viability (figure 1).…”

Chenier Morphodynamics on the Amazon-Influenced Coast of Suriname, South America: Implications for Beach Ecosystem Services

“…The large type 1 chenier beaches are the most suitable ecotope on the Guianas coast for nesting marine turtles, and are most typical of the vicinity of river mouths (active source zones), but this ecotope has become progressively shorter with beach shortening, fragmentation, and conversion of much of Braamspunt into a type 2 chenier (Figure 12). This condition is not ideal for successful nesting by marine turtles, which require stable sandy beaches, beaches not subject to overwash and strong infiltration, and beaches free of mud and organic matter (Kelle et al, 2007;Caut et al, 2010). Overwash processes are hazardous to turtle nests as they involve water infiltration and sand loading on the upper beach (Caut et al, 2010;Péron et al, 2013).…”

“…This condition is not ideal for successful nesting by marine turtles, which require stable sandy beaches, beaches not subject to overwash and strong infiltration, and beaches free of mud and organic matter (Kelle et al, 2007;Caut et al, 2010). Overwash processes are hazardous to turtle nests as they involve water infiltration and sand loading on the upper beach (Caut et al, 2010;Péron et al, 2013). Scarping and beach narrowing lower the available space for turtle nesting while generating a vertical beach face that may hinder turtle access to the beach.…”

Climate change and temperature‐linked hatchling mortality at a globally important sea turtle nesting site

“…While this study focuses on the effect of temperature on hatchling survival, there are a number of factors besides temperature that can contribute to hatchling mortality. For example, tidal overwash was shown to reduce hatchling survival in leatherback nests in French Guiana (Caut, Guirlet, & Girondot, 2010). Tropical storms and hurricanes can also reduce hatching success in loggerhead and green turtle nests in Florida (Lindborg, Neidhardt, Witherington, Smith, & Savage, 2016).…”