Conrad, Jeremy R.

Coastal mangrove forests are at risk of being submerged due to sea level rise (SLR). However, mangroves have persisted with changing sea levels due to a variety of biotic and physical feedback mechanisms that allow them to gain and maintain relative soil surface elevation. Mechanisms of surface elevation change (SEC) include leaf, wood, and root production, decomposition, and sedimentation/erosion, the combination of which result in a net change in the soil’s surface elevation. Therefore, mangrove forest resilience to SLR is dependent upon their ability to migrate inland or to build soil elevation at a rate that tracks with SLR. However, anthropogenic disturbances, such as altered hydrology and eutrophication, can degrade mangrove forest health and compromise their land building processes placing them at greater risk of succumbing to SLR.

From 2004 - 2007, the beach at Sandy Point National Wildlife Refuge (St. Croix,
USVI) experienced low summer erosion, which allowed native pioneer vegetation to
spread seaward and invade leatherback-nesting areas. The encroachment of vegetation
reduced nest survival. Here I describe the results of an experimental assessment of
vegetation control methods and of the effects of native vegetation on leatherback
hatching and emergence success. I tested four treatments: (i) naturally vegetated, (ii)
herbicide treated vegetation, (iii) mechanically removed above ground vegetation, and
(iv) non-vegetated (control) plots. Nests were relocated into each of the plot types then
left to incubate naturally. Hatching and emergence success was reduced when vegetation
was present. Vegetation was not adequately controlled by any of the methods tested. The
results identify future research needs for the development of appropriate management to
control the native vegetation and enhance leatherback nest productivity.