Mitigation of sea level rise effects by addition of sediment to shrimp ponds

In New Caledonia barren salt-pans located landward to mangroves are used for the construction of shrimp ponds. The existing farms are jeopardized by the projected rise in the sea level, because the landward boundaries of ponds are situated at the elevation reached by spring tides. One low-cost strategy for mitigating the effects of sea level rise is to raise the level of the bottom of ponds. To test the effectiveness of such an adaptation, we built 4 experimental ponds in the low-lying zone of an existing 10 ha shrimp pond. The level of the bottom of 2 ponds was raised by adding about 15 cm of agricultural soil. Placing agricultural soil in the pond did not impair the functioning of the shrimp pond ecosystem. On the contrary, it resulted in unexpectedly better shrimp production in the 2 ponds with agricultural soils versus control ponds. We conclude that placing a layer of soil inside shrimp ponds is a promising strategy for maintaining the viability of shrimp ponds as the sea level rises.

Sea-level control on the connection between shelf-edge deltas and the Bourcart canyon head (western Mediterranean) during the last glacial/interglacial cycle

A dense grid of high- and very high resolution seismic data, together with piston cores and borehole data providing time constraints, enables us to reconstruct the history of the Bourcart canyon head in the western Mediterranean Sea during the last glacial/interglacial cycle. The canyon fill is composed of confined channel���levee systems fed by a series of successively active shelf fluvial systems, originating from the west and north. Most of the preserved infill corresponds to the interval between Marine Isotope Stage (MIS) 3 and the early deglacial (19 cal ka BP). Its deposition was strongly controlled by a relative sea level that impacted the direct fluvial/canyon connection. During a period of around 100 kyr between MIS 6 and MIS 2, the canyon ���prograded��� by about 3 km. More precisely, several parasequences can be identified within the canyon fill. They correspond to forced-regressed parasequences (linked to punctuated sea-level falls) topped by a progradational-aggradational parasequence (linked to a hypothetical 19-ka meltwater pulse (MWP)). The bounding surfaces between forced-regressed parasequences are condensed intervals formed during intervals of relative sediment starvation due to flooding episodes. The meandering pattern of the axial incision visible within the canyon head, which can be traced landward up to the Agly paleo-river, is interpreted as the result of hyperpycnal flows initiated in the river mouth in a context of increased rainfall and mountain glacier flushing during the early deglacial.