Satellite image of a mangrove area in Punta Abreojos, Mexico. © Octavio Aburto/Scripps Institution of Oceanography.
In this satellite view of the mangroves in Punta Abreojos in the Mexican Pacific, water finds its way through the mangroves. These can now be better protected through a threat index.
Scientists at UC San Diego’s Scripps Institution of Oceanography and the Centro para la Biodiversidad Marina y la Conservación in Mexico have developed an index to assess the threat to mangrove populations. The “Mangrove Threat Index” is intended to help implement conservation measures before valuable ecosystems are destroyed, rather than after.
Mangrove forests occur on coastal areas in tropical regions. They offer protection from storms, are effective carbon stores and serve as nurseries for many fish species. This means that mangrove areas are also very important from an economic point of view. Nevertheless, around half of these ecosystems worldwide are endangered. In addition to long-term threats such as ocean warming and sea level rise, local human activities such as coastal development and pollution are leading to the destruction of coastal forests.
This is exactly what the newly developed index is based on: It assesses the threat to mangrove areas based on their proximity to roads, settlements and agricultural areas. The first assessment using satellite data was carried out in 2010 for 530 areas worldwide. In order to check whether the index makes a useful statement, the indices were now compared with data from 2020.
The result is clear: of the areas classified as medium to high risk, 78% of the areas actually showed a measurable loss of forested area in a ten-year comparison. In addition, the higher the risk was previously classified, the more extensive the destruction. The index can now be applied around the world to improve conservation efforts in mangrove areas.
The new approach also allows the urgency of interventions to be better assessed so that they can be used in a more targeted manner. “We are trying to break the trend of simply reporting how many hectares of mangrove forests are lost every year,” says Octavio Aburto, who worked on the study. “We created the index to measure the risk of mangrove loss so that conservation can prevent damage rather than simply react to it.”