Coastal and marine environments play a major role in carbon neutrality and as carbon markets. In the last few decades, coastal degradation, due to development pressures and climate change, has led to loss of habitats and ecosystem services, decreasing coastal health and attractiveness. Under increasing anthropogenic pressures, coastal systems are experiencing a decrease in resilience and, in some cases, may reach an ecological tipping point or threshold leading to a doubtful recovery. These pressures are exacerbating environmental stressors through changes to the fundamental drivers of ecosystems. An improved understanding of how multiple stressors such as warming, deoxygenation, and ocean acidification interact and subsequently impact species, habitat assemblages, and ecosystems is, thus, a high priority for coastal restoration and resource management, particularly for marine protected areas and vulnerability hotspots. Unexpected interactions between multiple stressors may affect natural processes, reducing coastal resilience and hampering recovery. The proposed session invites contributions on coastal processes and nature-based solutions that enhance resilience and support restoration based on natural dynamics, connectivity, and knowledge of multi-stressor interactions, which are the key to predicting future ecosystem states and avoiding irreversible impacts. Communications on how to combine observations and modelling across scales to assess rates of impacts/recovery are particularly welcome, including the definition of thresholds to irreversible states (tipping points) and coastal decision making. Within this framework, contributions exploring the potential applications of wetlands, seagrass meadows or vegetated dunes, as components of hybrid coastal protection are sought, including resilience and recovery assessments that address the river-coast continuum. Experimental or fieldwork approaches to understanding multistressor interactions are encouraged. These topics should form a fruitful session for discussing advances to enhance coastal resilience and recovery for delta-estuary-coastal systems.
Lead Organizer: Agustin Sanchez-Arcilla, Universitat Politecnica de Catalunya (UPC-BarcelonaTech) (agustin.arcilla@upc.edu)
Co-organizers:
Erica Ombres, NOAA Ocean Acidification Program (erica.h.ombres@noaa.gov)
Joanna Staneva, Helmholtz-Zentrum Geesthacht Zentrum Fur Material- Und Kustenforschunggmbh (HZG) (joanna.staneva@hereon.de)
Kimberly Puglise, NOAA NCCOS (kimberly.puglise@noaa.gov)
Mindert de Vries, Deltares (Mindert.deVries@deltares.nl)
Shiri Zemah, Reichman University, Interdisciplinary Center (IDC) (shiri.zemahshamir@idc.ac.il)
Presentations
06:30 PM
Summer Ωarg changes in Korean estuaries: a comparison of open and closed systems (4936)
Primary Presenter: Yujeong Choi, Research Institute for Basic Sciences Chonnam National University (meridachoi@gmail.com)
Estuaries, where freshwater from a river mixes with saltwater from the ocean, are highly susceptible to rapid decreases in pH (acidification) and aragonite saturation state (Ωarg) due to the poorly buffered water delivered by river water inputs. Additionally, anthropogenic activities, such as land use changes and nutrient pollution, can further lower the Ωarg in estuaries. However, acidification in eutrophic estuaries is not well understood. Here, we investigated Ωarg changes in three contrasting Korean estuary systems in summer; Han River (HR), an open estuary, and the Guem River (GR) and Youngsan River (YSR), closed estuaries where are enclosed by dam at the river mouth. Our findings showed that the mean Ωarg in HR, GR, and YSR estuaries are 1.6±0.7, 1.9±0.6, and 2.5±0.6, respectively. It is interesting that open estuary is lower than closed estuaries. During the summer, the river waters inputs delivered poorly buffered water to the upper estuaries, resulting in low Ωarg. However, seawater mixing toward Yellow Sea, with relatively higher, buffered the decrease in Ωarg at the lower estuaries. Our result suggest that river water inputs of low-to-intermediate total alkalinity can expand estuarine acidification zone, and the decrease in Ωarg is expected to accelerate over time in regions where the buffering capacity decrease. This low Ωarg can have significant impacts on the health and survival of estuarine organisms that rely on calcium carbonate structures.
06:30 PM
Rhodamine dye and drifter experiments for micro-tidal estuary dispersion (Fangar bay, Ebro Delta) (4977)
Primary Presenter: Raquel Peñas-Torramilans, Universitat Politècnica de Catalunya (UPC) (raquel.penas@upc.edu)
Estuaries and coastal bays are particularly vulnerable and highly productive areas from an ecological and socioeconomic point of view. These environments are increasingly threatened by anthropogenic pressures. Harmful algal blooms, anoxia-hypoxia events, and high-water temperatures are common threats that can negatively impact the ecosystem and its sustainable use. In this regard, episodes of water quality degradation have recently been reported in bays and coastal areas of the Mediterranean subject to freshwater fluxes, as is the case of Fangar Bay (Ebro Delta). This bay is characterized by a frequent vertical stratification due to freshwater inputs and low renewal rates. To address bay sustainability this paper analyses the temporal evolution of dispersion patterns, using field data from controlled releases of an innocuous tracer (Rhodamine). Results show that water dye dispersion is correlated with the gravitational (estuarine) circulation with seaward flows on the surface layer. The analysis is complemented with data from Lagrangian buoys, local currents from acoustic Doppler velocimeters, unmanned aerial vehicles (UAVs) images, meterological data and CTD surveys.Keywords: estuary; Ebro delta; dye release, diffusivity; rhodamine; Acknowledgements: This work has been funded by the project ECO-BAYS (PID2020-115924RB-I00)
06:30 PM
EXAMINING THE IMPACT OF ENVIRONMENTAL FORCING ON THE ATTENUATION CAPACITY OF MARSHES UTILIZED AS NATURAL COASTAL INFRASTRUCTURE (5496)
Primary Presenter: Matthew Falcone, University of California, Berkeley (matthew_falcone@berkeley.edu)
Over the past few decades, natural and nature-based features such as coastal vegetation have garnered increasing interest due to their capacity to provide a myriad of benefits, such as shoreline protection. Commonly referred to as green infrastructure, in contrast to traditional engineered shoreline infrastructure like seawalls, these ecosystems have been studied in an attempt to quantify their protective efficacy (e.g., wave attenuation) and value. This study aims to extend previous work on the complex hydrodynamics of saltmarshes to further examine the role that these systems play in energy attenuation. These findings have highlighted a dependence between attenuation efficacy and underlying forcing frequency, and the proposed work applies the non-hydrostatic mode of the popular wave model XBeach to examine the parameter space surrounding spectral energy dissipation in saltmarsh habitat. Preliminary model runs explore the interdependence between bulk drag coefficient and spectral energy dissipation. Utilizing existing empirical bulk drag formulations, dissipation at varying peak wave frequencies is examined for a range of mean water levels. Results aim to contribute to the improved characterization of how wave fields vary during the passage of a storm surge, where increased inundation of coastal vegetation alters the dynamics of the attenuation response.
06:30 PM
THERMAL INFRARED REMOTE FLUX MEASUREMENTS TO INFORM TIDAL RECONNECTION OF SUBSIDED SALT MARSHES AT CAPE COD NATIONAL SEASHORE (6056)
Primary Presenter: Evan Heberlein, Cornell University (eth47@cornell.edu)
The former salt marshes of the Herring River Estuary (HRE) in Massachusetts, USA were first diked and drained over a century ago, presenting an ideal case study for long-term, severe anthropogenic change in coastal wetlands. The US National Park Service and US Geological Survey are in the process of restoring these salt marshes through the replacement of Chequessett Neck Road Dike (CNRD) with an adjustable gated structure that will gradually reconnect the HRE to an unrestricted tidal regime. Tidal dynamics through the existing CNRD restriction present unique water velocity and flow rate measurement challenges that can be effectively addressed using Infrared Quantitative Image Velocimetry (IR-QIV), which tracks naturally-occurring thermal patterns on the water surface to measure surface velocities and fluxes. These flux measurements form an important baseline against which restoration targets for water quality, salinity, vegetation community succession, carbon fluxes, and other interacting biogeochemical variables can be evaluated. IR-QIV measurements at other sites could show the degradation of flow infrastructure or help understand hydrologic changes in diked coastal waters undergoing relative sea level rise. 2022 pre-construction field data from the HRE are statistically compared to outputs from 2-D and 3-D hydrodynamic models of the HRE and CNRD structure. Uncertainty and error of remote measurements are discussed in the context of model comparison. A feasibility study has shown that a carbon market would be viable in the HRE, and the potential use of infrared remote sensing for carbon flux quantification and validation in future field campaigns is presented as well.
06:30 PM
FROM DELTA TO THE SEA: MULTI-SCALE MODELLING OF BIOGEOCHEMICALFLUXES ALONG THE DANUBE LAND-SEA CONTINUUM (6596)
Primary Presenter: Lauranne Alaerts, ULiege (lauranne.alaerts@uliege.be)
The Danube River is the second longest river in Europe. It passes through 10 countries before emptying in the Black Sea. The Danube Delta, largest nearly undisturbed wetland in Europe, plays a buffering role between the river and the sea. Eutrophication in the coastal zone due to the increase of nutrients coming from the river causes important biological and financial losses since the 1970s. However, despite this and the importance of the Danube-Danube Delta-Black Sea system, the hydro and biogeochemical fluxes in this system remain largely understudied. We aim to model and quantify the interactions between the Danube delta and the Black Sea, from hourly to multi-annual time scales, using an unstructured-mesh hydrodynamic model. More specifically, we aim to evaluate how the biogeochemical fluxes of the North-western shelf (NWS) (i.e. limited by the 100m isobath) impact and are impacted by the small-scale variability of the three branches of the Danube Delta (i.e. Chilia, Sulina and Sfântul Gheorghe). We will then assess the potential impact of climate change and socioeconomic development on the transfer of water, salt and biogeochemical elements to the sea by running the model under different IPCC scenarios (SSP1-2.6 and SSP5-8.5).
06:30 PM
ACCRETION CAPACITY: HOW VEGETATION TRAITS PLAY A BARRIER ROLE ALONG SPANISH COASTLINE (7073)
Primary Presenter: Lucía Rodríguez-Arias, CEAB - CSIC (lucia.rodriguez@ceab.csic.es)
Coastal areas are dynamic and susceptible zones to natural and anthropogenic disturbances, fulfilling valuable ecosystem functions. Vegetation has been observed as an indirect contributor to coastline protection by assisting in the accumulation of sediment in these systems. In this study carried out along Catalan and Andalusian coast, we evaluated the mechanism by which vegetation retains sediment in coastal ecosystems, both emerged and submerged (dunes, salt marshes and seagrass meadows). This process is influenced by the presence or absence of vegetation and other ecological variables (patch area, species richness or dominance). Specifically, we carried out transects with a RTK GNSS receiver to accurately measure ground elevation inside and outside vegetation patches. We also collected aerial imagery using UAVs to expand the spatial scale. Our results show that the presence of vegetation facilitates sediment retention in all ecosystems. Greater species diversity and larger patch areas increased sediment retention capacity. In dune ecosystems, Ammophila arenaria was significantly better at retaining sediment than any of the other species surveyed, while in salt marshes and seagrass meadows we did not find significant differences between species. Our study sheds light to how vegetation presence, patch size, patch plant diversity and plant traits influence sediment retention capacity across habitat types and scales. This is not only important to face event-scale shoreline changes (e.i. individual storms), but also broader impacts related to climate change.
06:30 PM
HYDRODYNAMIC IMPACT OF DEFORESTATION IN MANGROVE FORESTS (7131)
Primary Presenter: Johann Delgado, Cornell University (jkd78@cornell.edu)
Conservation of mangroves is a promising approach to climate-change mitigation and adaptation of coastal systems. Mangroves are known as “champions” of sequestering soil carbon, ~50 times more effective than tropical forests. Deforestation can create new channels with relatively high-velocity flows due to a significant reduction in drag forces. These flows can enhance removal of soil carbon from the channels. Paradoxically, the presence of these channels contribute to a reduction of flow velocities within the adjacent forest and potentially facilitate sedimentation. In this study, we conducted laboratory experiments using a simplified model of mangrove roots, which were represented by random and emerged cylinder arrays that partially fill the flume in the lateral. Spatial surface velocities were acquired using optical (PIV) and acoustic (ADV) techniques. Results show flow in the unvegetated region accelerates linearly and reaches mean streamwise velocities (U) over two times the incident velocity. The lateral velocity is ‘relatively high’ (~0.1U) at the leading edge of the vegetation, but with a rapid decay within the vegetation. A strong mass and turbulent kinetic energy transfer from the vegetated area into the main channel was observed. Spatial data suggest the formation of secondary flows in the main channel that contribute to the redistribution of momentum and mass from the bottom and the vegetated region to the free surface. These experiments helped to obtain a better understanding of the impact of channelization of mangrove forests and prevent irreversible impacts.
06:30 PM
BIOGEOCHEMICAL STUDIES OF RIVERS, MILWAUKEE HARBOR, AND COASTAL LAKE MICHIGAN RECEIVING WATERS: NEARSHORE AND HARBOR HABITAT RESTORATION (7157)
Primary Presenter: Carmen Aguilar, University of Wisconsin - Milwaukee (aguilar@uwm.edu)
Widespread closures of COVID-19 resulted in favorable ecosystem effects for watershed, riverine, coastal, and SW Great Lake Michigan water. Between March and July aquatic resources had extended relief from inhibitory inputs and would have flushed existing dissolved and suspended materials of human origin. Dissolved Fe and Mn, crucial phytoplankton nutrients, remained elevated in the rivers and harbor, and declined slowly with distance from outflows within the first 5 km. Toxic or extreme micronutrient trace metals Mo, Zn, Cu, Cd, Se, As, and others were below detection (ca. 20nM) at all locations prior to reopening. Moving through the continuum, repeated expeditions from the lower rivers into Lake Michigan encountered unusually high proportions >30% of larger phytoplankton as far as 15km out; this anomalous size distribution was accompanied by extraordinary longevity of phytoplankton nearshore abundance into July following early stratification. Reversed seasonality of post-mussel diatom resurgence has additionally provided new high nutritional input into nearshore coastal ecosystems during late summer and fall. Robust biomass-specific productivity regime with maximum carbon dioxide fixation commonly 6-15 µgC/ µgCHLa/hour (PBm), was double or more previous coastal zone values. Projected dredging of river-harbor legacy sediments to remove particle-bound forever contaminants (PFAS, PCB, PAH) will unwittingly release porewater nutrients into the water column. These are mostly reduced, e.g., ammonium, Fe++, Mn++, and lead to potential eutrophication downstream into coastal areas.
06:30 PM
Connecting the near-shore with the open ocean: coastal ocean acidification conditions in U.S. National Park sites (7228)
Primary Presenter: Leticia Barbero, University of Miami (leticia.barbero@noaa.gov)
Most of the recreational fishing, aquaculture and tourism activities take place in near-shore estuarine and coastal regions. The effects of land-side processes such as river discharge and run-offs, and ocean-side processes on these regions are often not well known. To help fill this gap for coastal waters of the US East coast and Gulf of Mexico, we have entered into a collaboration with the US National Park Service to collect carbonate parameter samples within park boundaries in addition to other water quality measurements. The participating parks cover a wide range of ecosystems, including estuaries, salt marshes, mangroves, etc and climate systems ranging from subtropical to humid continental. Samples are routinely collected in winter and summer, and whenever an ocean acidification cruise is taking place (every 4 years in summer), sample collection is coordinated with the cruise to connect the near-shore with the open ocean conditions. Here we present preliminary results of our efforts. Despite the sparsity of measurements, our data show how varied the carbonate chemistry and OA conditions are in these parks and how essential it is to increase data collection to improve coastal models and provide realistic validation data. The dataset will also be useful for park managers working to preserve coastal ecosystems in our National Parks.
SS032P River-Delta/Estuary-Coast Continuums Under Multi-Stressor Interactions: Connectivity and Dynamics to Enhance Resilience
Description
Time: 6:30 PM
Date: 7/6/2023
Room: Mezzanine