The environment and ecosystems, such as forests, marshes, and grasslands, are essential parts of the global water cycle. The continuous health of ecosystems and the broader environment are ultimately what all freshwater depends on, and realizing the water cycle as a biophysical process is crucial to accomplishing sustainable water management. Inland and coastal water environments have highly diversified biodiversity, which is also very significant to regional lifestyles and economy. However, the conservation of this diversity is not always taken into consideration during development activities, and it is inadequately reflected during the planning stage. The good news is that there are lots of choices for conserving the freshwater ecosystem and environment, but they must be taken right away.

Greater investments are now widely acknowledged as being necessary to safeguard aquatic ecosystems and the environment from the damaging effects of human development in all of Eastern and Southern Africa taking into consideration the "blue economy" sector. The potential of the oceans to meet sustainable development needs is enormous; but only if they can be maintained in and/or restored to a healthy, and productive state. But ongoing trends of exploitation and degradation of marine and coastal ecosystems show that endeavors to date have been insufficient and that more needs to be and must be done to improve human well-being and social equity, while significantly reducing environmental risks and ecological scarcities. 

On the other side, the polluter pays principle is either not implemented at all or is done so extremely slowly. Decision-makers are given the ability to engage large productive water users with the clear end objective of sustainability when ecological demands are integrated into water management procedures. This also applies to the concept of "blue economy" which forms an integral part of the region. In light of global issues like urbanization and climate change, it becomes less subjective to address the challenge of finding the right balance between allocating water for direct human use (agriculture, power generation, domestic purposes, and industry) and indirect use (sustenance of ecosystem goods and services). Increased knowledge of the connections between the various water sources and users necessitates acknowledging the existence of ecosystem borders at the national and transnational levels in addition to hydrological boundaries.

The papers in this sub-theme should discuss novel approaches and best practices in environmental impact assessment, valuation of ecosystem goods and services, establishing ecosystem boundaries, including ecosystem goods and services in the development of water resources, pollution prevention and treatment, river basin management, wise use of water-linked ecosystems and people's livelihoods, sustainable use of blue resources for economic development and other topics.