![]() ![]() The published data product includes 11 sets (1 for each time step) of global tidal flat extent maps at 30 meter Ground Sample Distance (GSD AKA resolution). The goal of data summarization is to distill the large raster dataset into simple tabular data which can be integrated into the OHI annual analysis as new data layers for 2022 and beyond. This post will give a brief explanation of tidal flat habitat, explore the new dataset, and demonstrate how to programmatically summarize the data in the R software environment. The three new data layers created are tidal flat extent (measured in km 2), tidal flat trend (proportional change), and tidal flat condition (current status compared to historic status). Tidal flats will affect the OHI global scores by adding additional layers to the habitat subgoal and carbon storage goal. The interface of coastal development with tidal flat habitat off Redwood City, California (Photo: Jitze Couperus). “Extensive degradation from coastal development, reduced sediment delivery from major rivers, sinking of riverine deltas, increased coastal erosion, and sea-level rise signal a continuing negative trajectory for tidal flat ecosystems around the world.” This new dataset has given OHI the opportunity to further improve our methods and in turn, the ability to understand the health of the world’s oceans. 2019), which used satellite imagery and machine learning methods to classify tidal flat habitat from over 700,000 satellite images between 19. The data come from a paper, The global distribution and trajectory of tidal flats (Murray et al. This vital habitat is distributed globally, but up until this recently there was very limited data on the extent of these ecosystems, especially at the global scale. Tidal flat habitat is defined as sand, rock, or mud flats that undergo regular tidal inundation. He said further analysis would be needed of the ongoing impact of the other key threat – sea level rise.The Ocean Health Index has decided to update the habitat subgoal of biodiversity by adding tidal flat ecosystems to complement the existing habitat types (seagrass, kelp, coral reefs, mangroves, salt marsh, sea ice edge, and soft bottom). Murray said dams were one of the major drivers of reduced sediment flows from rivers. Reduced sediment flows from rivers around the world had also led to a reduced amount of sediment being deposited as tidal flats. Murray said airports, aquaculture and other infrastructure that had been built on top of tidal flats in countries such as China were major threats. In these locations, which were mostly in China, the US and countries in the Middle East, they found declines in tidal flats of 16%.įor a further 61% of the world, there was enough data to analyse changes from 1999 to 2016 and the research showed declines of 3.1% in this period. In Australia, they occur all over the country, including places such as Moreton Bay in Queensland and along the Gulf of Carpentaria.įor 17% of the world, there was enough data available to measure declines from 1984 to 2016. In parts of China and western Europe, they found tidal flats that were up to 18km wide. ![]() They found that tidal flats, as an ecosystem, were as extensive globally as mangroves and that coastal development and sea level rise, in particular, were causing their decline. The research team worked with Google and used its computing resources to analyse every satellite image ever collected of the world’s coastlines. “It’s all over the planet and highly susceptible to threats but we haven’t known where they are, which has limited the ability to monitor them.” Nicholas Murray, the study’s lead author and a senior research fellow at the centre for ecosystem science at the University of New South Wales, said because tidal flats were often at least partially covered by water they had been difficult to monitor in the past. ![]()
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