Densely populated coastal river deltas are very vulnerable to compound flood risks, coming from both oceanic and riverine sources. Climate change may increase these compound flood risks due to sea level rise and intensifying precipitation events. Here, we investigate to what extent nature-based flood defence strategies, through conservation of mangroves in a tropical river delta, can contribute to mitigate the oceanic and riverine components of compound flood risks. While current knowledge of estuarine compound flood risks is mostly focussed on short-term events such as storm surges (taking one or a few days), longer-term events, such as El Niño events (continuing for several weeks to months) along the Pacific coast of Latin America, are understudied. Here, we present a hydrodynamic modelling study of a large river delta in Ecuador aiming to elucidate the compound effects of El Niño driven oceanic and riverine forcing on extreme high water level propagation through the delta, and in particular, the role of mangroves in reducing the compound high water levels. Our results show that the deltaic high water level anomalies are predominantly driven by the oceanic forcing but that the riverine forcing causes the anomalies to amplify upstream. Furthermore, mangroves in the delta attenuate part of the oceanic contribution to the high water level anomalies, with the attenuating effect increasing in the landward direction, while mangroves have a negligible effect on the riverine component. These findings show that mangrove conservation and restoration programs can contribute to nature-based mitigation, especially the oceanic component of compound flood risks in a tropical river delta.
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RBINS Staff Publications 2024
Fish represent a key economic, social and ecological group of species that humans have exploited for tens of thousands of years. However, as many fish stocks are going into decline and with little known about the anthropogenic impacts on the health of the marine ecosystem pre-Industrial Revolution, understanding historical and archaeological exploitation of fish species is key to accurately modelling these changes. Here, we explore the potential of collagen peptide mass fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS) for identifying fish remains from the Medieval (fifteenth century) Newport ship wreck (Wales, UK), and in doing so we establish a set of biomarkers we consider useful in discriminating between European fish taxa through the inclusion of over 50 reference taxa. The archaeological results identified nine distinct taxonomic groups, dominated by ling (> 40%), and a substantial amount of cod (> 20%) and hake (~ 20%). The vast majority of samples (> 70%) were identified to species level, and the inability to identify the remaining taxonomic groups with confidence using ZooMS was due to the fact that the reference collection, despite being relatively large in comparison to those presented in mammalian studies, reflects only a small proportion of fish biodiversity from this region. Although the results clearly demonstrate the potential for ZooMS as a means of fish bone identification, the sheer number of different fish species that potentially make up ichthyoarchaeological assemblages leads to obvious requirements for the analysis on much greater numbers of modern reference specimens, or the acquisition of collagen sequences.
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RBINS Staff Publications 2022
