Artificial nesting habitats as a conservation strategy for turtle populations experiencing global change

Abstract

Diamondback terrapins (Malaclemys terrapin) inhabit estuaries in eastern USA and may tolerate salinity of sea-water for short durations. Many North American estuaries are adversely affected by anthropogenic impacts, such as pollution, dredging and invasion by non-native plants. Many nesting areas have been altered or destroyed, causing terrapins to nest on roadsides and artificial islands made of dredged substrate from bottom sediments. Shading by non-native plants may suppress development and reduce survival of embryos. In Barnegat Bay, New Jersey, USA, there is a mosaic of natural and degraded terrapin nesting habitats. We investigated the effects of dredge soil and shade on the hatching success of diamondback terrapins to determine whether nesting habitat could be increased by using dredged bottom sediments. In year 1, unshaded nests in natural loamy-sand had the highest hatching success (55.2%), while nests in dredge soil produced no hatchlings. In year 2, nests in unshaded loamy-sand had a hatching success of 85.3%, whereas those in dredge soil, aged 1 year, had a hatching success of 59.4%. Dredge soil improved as an incubation substrate after aging 1 year by the washout of salt. Nest temperatures were generally cool and produced mostly male hatchlings. Uncontaminated dredge soil may provide suitable nesting substrates for diamondback terrapins if used after one year, and may be particularly beneficial if used for constructing islands that provide new nesting sites with reduced access of mammalian predators.

Nesting Habitat Creation Enhances Recruitment in a Predator‐Free Environment: Malaclemys Nesting at the Paul S. Sarbanes Ecosystem Restoration Project

“…Within‐nest survivorship for nests that avoided predation on Poplar Island was over 60% and each year ranged from 0 to 100%. Wnek et al () noticed a decrease in survival of terrapin nests on dredge sediments immediately after deposition, but nest survivorship increased on these materials in the second year of their study. The only other published natural within‐nest survivorship for the turtle Kinosternon baurii (striped mud turtle), ranged from almost 10 to 80%, depending on the habitat type (Wilson ).…”

Factors affecting spatiotemporal patterns of nest site selection and abundance in diamondback terrapins

“…Similarly, at local scales, developed areas typically lack suitable nesting habitat (although DBT in Wellfleet are known to nest in altered landscapes such as lawns, dirt roads, and driveways) and are subject to high levels of anthropogenic disturbance during nesting attempts (Butler et al, 2018; Robert Prescott, R. P. pers. obs; Wnek et al, 2013). Moreover, highly developed areas are more likely to lack suitable offshore habitat (e.g., saltmarsh) and would therefore be avoided by DBT at larger spatial scales (Bilkovic et al, 2012).…”

Between the bay and a hard place: Altered diamondback terrapin nesting movements demonstrate the effects of coastal barriers upon estuarine wildlife

“…For example, Roosenburg et al () describe the restoration of an offshore island within the Chesapeake Bay, Maryland that has created productive nesting habitats for terrapins away from the complex threats present around mainland nesting sites. Knowing that terrapins will use artificial nesting habitats, we recommend their development in Barnegat Bay from washed dredge soils (Wnek et al ). By recognizing and addressing manmade barriers as a contributing threat to terrapins, better management strategies can be developed to conserve the species.…”