Marine plant dispersal and connectivity measures differ in their sensitivity to biophysical model parameters

Schlaefer, Jodie A.; Carter, Alex; Choukroun, Séverine; Coles, Robert G.; Critchell, Kay; Lambrechts, Jonathan; Rasheed, Michael A.; Tol, Samantha; Grech, Alana

doi:10.1016/j.envsoft.2022.105313

Cited by 7 publications

(4 citation statements)

References 66 publications

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“…In this study, we use the 2D barotropic unstructured-mesh ocean model SLIM (Lambrechts et al, 2008). SLIM has already been applied multiple times to the GBR for connectivity, sediment transport and plastic pollution studies (e.g., Lambrechts et al, 2010;Thomas et al, 2014Thomas et al, , 2015Critchell et al, 2015;Grech et al, 2016;Schlaefer et al, 2022;Saint-Amand et al, 2022).…”

Section: Hydrodynamicsmentioning

confidence: 99%

How fine is fine enough? Effect of mesh resolution on hydrodynamic simulations in coral reef environments

Saint-Amand¹,

Lambrechts²,

Thomas³

et al. 2023

Preprint

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Coral reef environments are biodiversity hotspots that provide many services to coastal communities. They are currently facing an increasing anthropogenic pressure that jeopardises their survival. Numerical ocean models are an important tool to understand the functioning of coral ecosystems and the mechanisms ensuring their resilience. However, simulating the water circulation through reef systems is challenging because of their naturally complex topography and bathymetry. Many ocean models used for such applications have a spatial resolution coarser than the scale of individual reefs, which puts into question their suitability for the task. Here, we assess the sensitivity of a coastal ocean model's outputs to its spatial resolution when simulating the water circulation in the entire Great Barrier Reef (Australia), the largest coral reef system in the world. We consider the same model with five different resolutions near reefs, ranging from 250 m to 4 km, and compare the model outputs at different locations around reefs and in the open ocean. We also simulate the transport of passive particles released from those different locations. Our results show that the simulated tidal signal is similar for all five resolutions. However, strong discrepancies (> 10 cm/s) in the current velocity are observed near the reefs and along the rugged coastline. When using a coarse-resolution model, the amplitude of the currents is overestimated over reefs, and underestimated between them. We find that validating the model at deep water mooring sites is not sufficient to ensure it performs well close to reefs. Discrepancies in currents lead to more directional and uniform tracer dispersal patterns on coarse-resolution meshes that contrast with the more dispersive patterns observed on fine-resolution meshes. Those differences at the reef level have a large cumulative effect when simulating transport processes over several weeks. Our results suggest that ocean circulation and transport simulations in coral reef environments should be based on model resolutions finer than the reef scale, which generally means a maximum resolution of about 250-500 m.

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Section: Hydrodynamicsmentioning

confidence: 99%

How fine is fine enough? Effect of mesh resolution on hydrodynamic simulations in coral reef environments

Saint-Amand¹,

Lambrechts²,

Thomas³

et al. 2023

Preprint

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“…The immediate scientific value of projects like this have been demonstrated on Queensland's east coast, where the Great Barrier Reef World Heritage Area (GBRWHA) data synthesis (Carter et al 2021 a ) has been used to answer a number of key ecological questions, including the probability of seagrass distribution and communities (Carter et al 2021 d ), defining the desired state of seagrass communities in the Townsville region (Collier et al 2020) and GBRWHA (Carter et al 2022 b ), examining management targets for rivers influencing seagrass habitat (Collier et al 2021; Lambert et al 2021), and in designing a Great Barrier Reef‐scale monitoring program (Udy et al 2019). Seagrass data has also been used on the Great Barrier Reef to model risk exposure (Grech et al 2011; Grech et al 2012; Bainbridge et al 2018); propagule distribution (Grech et al 2016; Schlaefer et al 2022); developing a National Ocean Account in Australia (https://www.abs.gov.au/articles/towards-national-ocean-account); and connectivity among meadows (Tol et al 2017; Grech et al 2018). We now make available data for the Gulf of Carpentaria and Torres Strait to answer similarly important questions for this region.…”

Section: Data Use and Recommendations For Reusementioning

confidence: 99%

“…We now make available data for the Gulf of Carpentaria and Torres Strait to answer similarly important questions for this region. These data are already being used to initiate hydrodynamic modeling approaches to better understand seagrass connectivity and resilience in the Torres Strait (Schlaefer et al 2022). By ensuring consistency in the structure of both point and polygon (meadow) data sets for the Great Barrier Reef and this project, and making these publicly available on eAtlas, we provide a mechanism for additional data to be added, archived, and easily compared.…”

Section: Data Use and Recommendations For Reusementioning

confidence: 99%

Seagrass spatial data synthesis from north‐east Australia, Torres Strait and Gulf of Carpentaria, 1983 to 2022

Carter,

McKenna,

Rasheed

et al. 2023

Limnol Oceanogr Letters

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The Gulf of Carpentaria and Torres Strait in north‐eastern Australia support globally significant seagrass ecosystems that underpin fishing and cultural heritage of the region. Reliable data on seagrass distribution are critical to understanding how these ecosystems are changing, while managing for resilience. Spatial data on seagrass have been collected since the early 1980s, but the early data were poorly curated. Some was not publicly available, and some already lost. We validated and synthesized historical seagrass spatial data to create a publicly available database. We include a site layer of 48,612 geolocated data points including information on seagrass presence/absence, sediment, collection date, and data custodian. We include a polygon layer with 641 individual seagrass meadows. Thirteen seagrass species are identified in depths ranging from intertidal to 38 m below mean sea level. Our synthesis includes scientific survey data from 1983 to 2022 and provides an important evidence base for marine resource management.

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“…To simulate the ocean circulation, we use the multiscale coastal ocean model SLIM ("Second-generation Louvain-la-Neuve Ice-Ocean Model", https://www.slim-ocean.be), which relies on unstructured meshes to smoothly adapt the spatial resolution to the coastal topography. SLIM was first applied to the GBR by Lambrechts et al 38 , and then used for several connectivity and dispersal studies 20,[39][40][41][42][43][44][45][46] . In this study, we simulated coral larval dispersal driven by the currents computed on five different meshes whose finest spatial resolution ranges from 250 m to 4 km.…”

Section: Introductionmentioning

confidence: 99%

Biophysical models resolution affects coral connectivity estimates

Saint-Amand

Lambrechts

Hanert

2023

Preprint

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Estimating connectivity between coral reefs is essential to inform reef conservation and restoration. Given the vastness of coral reef ecosystems, connectivity can only be simulated with biophysical models whose spatial resolution is often coarser than the reef scale. Here, we assess the impact of biophysical models resolution on connectivity estimates by comparing the outputs of five different setups of the same model with resolutions ranging from 250 m to 4 km. We show that increasing the model resolution around reefs yields more complex and less directional dispersal patterns. With a fine-resolution model, connectivity graphs have more connections but of weaker strength. The resulting community structure therefore shows larger clusters of well-connected reefs. Virtual larvae also tend to stay longer close to their source reef with a fine-resolution model, leading to an increased local retention and self-recruitment for species with a short pre-competency period. Overall, only about half of the reefs with the largest connectivity indicator values are similar for the finest and coarsest resolution models. Our results suggest that reef management recommendations should only be made at scales coarser than the model resolution. Reef-scale recommendations can hence only be made with models not exceeding about 500 m resolution.

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Marine plant dispersal and connectivity measures differ in their sensitivity to biophysical model parameters

Cited by 7 publications

References 66 publications

How fine is fine enough? Effect of mesh resolution on hydrodynamic simulations in coral reef environments

How fine is fine enough? Effect of mesh resolution on hydrodynamic simulations in coral reef environments

Seagrass spatial data synthesis from north‐east Australia, Torres Strait and Gulf of Carpentaria, 1983 to 2022

Biophysical models resolution affects coral connectivity estimates

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