Algal mat seaweed mapping toolkit

This is the RaNTrans mapping portal, providing free and open access to the definitive source of geographic data products and services that we have created during our research. All content is provided under the Open Government Licence v3.0, except where otherwise stated, and acknowledgement is required on any materials that are reproduced elsewhere.

We are currently preparing the mapping data for publication, and will provide links to it below once it is available.

The RaNTrans Project is co-financed by the European Regional Development Fund through the Interreg France (Channel Manche) England Programme.

The RaNTRans mapping data provides authoritative geographic information about the seaweed macro algal mat coverage and other coastal marine vegetation in the transitional natural environment across southern England and Northern France (the Channel Manche region). Also featured is a hydrodynamic model of tidal flow and nutrient distribution that influences eutrophication.

Why is this important?
This toolkit provides good practical guidelines and have been developed for use by decision makers, researchers, government officers, conservation practitioners, community leaders, and others.

These guidelines aim to promote good practice (evidence-based decision making) and alternative ways to improve how we tackle eutrophication in coastal areas with transitional waters, as well as helping us to improve water quality and wildlife in the seascape, and socio-economic benefits from seaweed macro algae. Focusing on the geospatial abundance of seaweed macro algae for analysis and nutrient bioremediation decision making, they are not limited to any macro algae species or regions of the world.

This data will be presented on an interactive map that can be accessed and explored using a variety of mapping tools.

We will provide a link to the interactive map once the data is finalised. For now, please see the data samples below.

These satellite images of the Ledano estuary were captured during July and August 2021. Algae coverage was found to be at 790,974 m², including 721,638 m² with a 0.4 threshold, and 803,952 m² with a 0.3 threshold within the fuzzy classification index.

The fuzzy classification programmes have some difficulties in detecting shiny macro algal mat, but the results are confirmed by the validation data as shown in the images. There is less macro algal mat in some of the areas under consideration, as shown where the classification did not detect some pixels covered by a thin macro algal mat layer. Some of these areas are confirmed as water channels from the ground truthing data.

These satellite images of Langstone Harbour and its estuaries were captured during September 2022. They show algal mat coverage similar to that seen at the Ledano estuary and mudflats. Dominant algal mat locations are shown by the fuzzy index and validation results.

How the data was created

Our algal mat probability data and mapping layer was created from ARGANS satellite imagery and ground-truth information for each representative coastal vegetation. To identify high risk areas for algal mat development – using Environment Agency water quality data – Cefas also created hydrodynamic water quality datasets to indicate distribution and flow of nutrients in Poole Harbour and Langstone Harbour (only).

How to use this data

These datasets and maps can be used to indicate the abundance of seaweed algal mat in the FCE region and their impact or management.