The intensifying power of windstorms, a direct consequence of a changing climate, is proving to be a significant driver of nutrient dynamics in coastal wetlands. Our recent study, conducted in the inner Cadiz Bay, offers a granular perspective on how these extreme events transiently reshape shallow coastal environments. By meticulously sampling before, during, and after a windstorm event (WSE) across sites with distinct sediment compositions – sandy and muddy – we observed a clear and immediate transfer of matter from the sediment to the water column. This transfer manifested as a notable increase in total suspended solids (TSS) and chlorophyll a (Chla) within the water column, directly correlating with wind speed. This empirical observation underscores the direct physical impact of wind energy on coastal sediment resuspension.
While the physical resuspension of sediment is evident, the behavior of dissolved inorganic nutrients presents a more nuanced picture. Although nutrient concentrations also rose during the WSE, their relationship with wind speed was not as direct as that of TSS and Chla. This suggests that the increased nutrient load is not solely a result of immediate release from disturbed sediments. Instead, it indicates that subsequent biogeochemical processes within the water column play a crucial role in modulating nutrient availability. Furthermore, satellite imagery from Sentinel-2 provided valuable spatial context, confirming the water column impacts while also revealing a significant degree of heterogeneity in the storm's effects across the bay. This demonstrates the power of integrated observational methods, combining in-situ measurements with remote sensing, to capture the full scope of complex environmental responses.
The windstorm's influence extended beyond the water column, measurably altering sediment characteristics. We observed changes in oxygen distribution, net metabolism, and the concentrations of Chla, organic carbon, and total nitrogen. These effects, critically, varied depending on the specific sediment type and local hydrodynamic conditions, highlighting the localized nature of these impacts within a broader event. Crucially, our findings indicate that these changes are generally transitory, with the system largely returning to its pre-storm state relatively quickly. Nevertheless, the WSE demonstrably intensified benthic-pelagic coupling, leading to increased resuspension and nutrient exchange. The resulting outwelling from these shallow environments has the potential to significantly influence coastal productivity, a critical factor for understanding broader marine ecosystem health and resilience in the face of accelerating climate change.