Identifying bottlenecks for subtidal eelgrass growth in the Dutch Wadden Sea

Description

Extensive subtidal eelgrass (Zostera marina) meadows grew in the Western Dutch Wadden Sea. Since the 1930s, because of the wasting disease and construction of the Enclosure Dam, the population vanished completely. Seagrass shoots induce positive feedback by reduced hydrodynamic forcing, while dense root mats increase sediment stability. This leads to ameliorated conditions, also benefitting other species. In a system without seagrass, self-facilitation is lacking. To identify the most important bottlenecks limiting seagrass growth, we used artificial structures inducing similar feedback. In a full-factorial field experiment, we tested how buried structures and sandbag walls influenced survival and persistence of transplantation units. Shoots were tied to anchoring devices to prevent washing-out. A pronounced edge-effect of the walls reversed their facilitating effect and caused erosion and sedimentation, leading to less survival and persistence. Sediment stabilizing structures increased survival significantly. After one month, more than 90% of the transplant units were still present, proving that the transplantation technique works in the Dutch Wadden Sea. Ultimately, after three months, all seagrass shoots died. Hypotheses for the die-off are high salinity differences between harvest site and transplantation site, and/and poor light conditions. These particular bottlenecks should be further investigated in a lab experiment.

Periode	21-sep.-2022
Evenementstitel	Netherlands Annual Ecology Meeting 2022
Evenementstype	Conference
Conferentienummer	15
Organisator	Netherlands Ecological Research Network (NERN)
Locatie	Lunteren, NetherlandsToon op kaart
Mate van erkenning	National