Standard Presentation Australian Marine Sciences Association 2026 Conference

Catchment State Responsibilities in Managing Land-Based Pollution from River Discharges: Insights from the Indian Ocean (139476)

Georgea Kamara 1 , Julia Pascal 1 , Jennie Mallela 2 , Jamie Pittock 1 , Alistair Graham 3 , Melyne Tarer 4 , Lara van Niekerk 5 6 , Stephen J Lamberth 6 7 , Jennifer L Lavers 8 , Heidi L Taylor 8 , Bhavnah Komul Kalidin 1
  1. Fenner School of Environment and Society, Australian National University, Canberra, ACT, Australia
  2. Research School of Biology, The Australian National University, Canberra, ACT, Australia
  3. Conservation consultant, Hobart, Tasmania, Australia
  4. IORA Secretariat, The Indian Ocean Rim Association, Ebene, Plaines Wilhems, Mauritius
  5. Coastal Systems and Earth Observation Research Group, Council for Scientific and Industrial Research (CSIR), Rosebank, Cape Town, South Africa
  6. Coastal and Marine Research Institute , Nelson Mandela University, Gqeberha, Cape Town, South Africa
  7. Inshore Resources Research , Department Forestry, Fisheries & Environment, Foreshore, Cape Town, South Africa
  8. Tangaroa Blue Foundation, Quedjinup/Dunsborough, Western Australia, Australia

Freshwater and marine ecosystems worldwide are experiencing declines in water quality and quantity due to multiple anthropogenic pollutants. These declines in ecosystem health have complex social and ecological consequences, particularly at the dynamic interfaces between land, freshwater, estuarine, coastal, and ocean ecosystems. Because these ecosystems are interconnected, effective resource management requires identifying which catchments contribute the most water, sediments, and organic matter to the oceans, which are heavily impacted by human activity, and which remain relatively pristine.  The Management of Rivers Discharging into Ocean Realms (MORDOR) initiative uses the Indian Ocean as a case study to introduce the concept of “ocean catchments and their catchment states,” clarifying management responsibilities and highlighting opportunities for cooperation or new initiatives. A literature review was conducted to assess the current knowledge on key pollutants entering the Indian Ocean from river systems and identified critical knowledge gaps.  Geographic information systems were then used to map catchment areas by key river catchments and national jurisdiction, identifying the “catchment states” responsible for management and suggesting ways to enhance their effectiveness.  Five key transboundary mitigation and management opportunities were identified. Finally, priority transdisciplinary research needs are outlined to strengthen governance and ecological outcomes across these large-scale social-ecological systems.

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