New study highlights urgent conservation efforts needed to preserve world heritage status of Isimangaliso Wetland

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An analysis of 30 years of satellite images has led researchers from the University of Fort Hare to raise the alarm about the shrinking Isimangaliso Wetland in Kwa-Zulu Natal.

Analyzing satellite images of the past 30 years, the researchers found that the wetlands in the Isimangaliso Wetland Park, a world heritage site, have shrunk by 5% between 1987 and 2017.

The Isimangaliso Wetland in KwaZulu-Natal is an invaluable natural resource providing resources and services to people, a habitat for several species, and a sought-after tourism destination.

“This wetland depletion might have a significant impact on biodiversity including humans and animals as well as plants thus diminishing its world heritage status. Consequently, this natural gift needs to be conserved to create a liveable environment for wetland animals to moderate local climate as well as preserve human wellness and protection by reducing flood disaster disasters and maintaining efficient water quantity and quality in the area,” according to the paper.

The Isimangaliso Wetland Park is 275 km north of the port city of Durban on the east shoreline of KwaZulu-Natal, South Africa. It is a world heritage site known for its diverse and rich biodiversity.

It includes 280 km of coastline stretching from South Africa’s border with Mozambique to Mapelane south of the Lake St. Lucia estuary. The wetland stretches over 3280 km². It is a world heritage site known for its wide variety of animal, aquatic, and marine life. It is an area of rich biodiversity and encompasses various ecosystems: coral reefs, shorelines, subtropical woodlands, savanna, and wetlands.

The researchers found that the size of the wetlands in the park was shrinking. In a novel approach to studying the wetlands, they used geospatial techniques and satellite images to study the wetland’s transformation and detect shifts in biodiversity due to both natural and human processes.

“Between 1987 and 2017 an analysis of the condition of these wetlands has revealed significant depletion of water. It appears to be due to human activity which may include climate change, built-up areas, and agricultural activities in the area,” the paper reads.

In their study, researchers attached to the Department of Geography and Environmental Science, the University of Fort Hare’s Faculty of Science and Agriculture, used geospatial science coupled with satellite imagery to quantify wetland depletion and changes. 

They used Landsat Thematic Mapper images for 1987, 1997, and 2007 and Landsat 8 Thermal Infrared Sensor and Operational Land Imager imagery for 2017 from the United States Geological Survey (USGS) archive. The Landsat satellites are managed by the American Space Agency (NASA) and the United States Geological Survey.

The researchers used a fine-scale Normalised Difference Water Index (NDWI) and change detection analyses to reach their conclusions. For instance, NDWI highlighted open water features in a satellite image allowing for more accurate analysis.

“These results open up new opportunities to examine the current size of the Isimangaliso Wetland and its potential impact on biodiversity and urgent intervention in conserving the wetland,” they wrote.

“The result from Landsat images data shows land use activities have

reduced wetland extent and distribution by 5% between 1987 and 2017. Wetland loss could be a significant problem for the local communities that depend on them as a natural resource as well as for many wetland species.

“Such significant problems illustrate the need for improved management by both the communities and the environmental policy-makers. The wetland map and land-use change assessment on wetlands can help to underscore the wetland depletion and its attendant vulnerability as well as serve as a guide for land-use practices that have a direct and indirect effect on wetlands,” the paper concluded.