How an invaluable river system in Cambodia inspired one scientist’s career

Villagers prepare for their day on beached boats.

Around the globe, we find numerous villages, towns, and cities built along the banks of rivers and lakes—a testament to the critical role freshwater plays in our lives. This precious resource provides drinking water, food, trade opportunities, and transportation navigation. A prime example of this is the Cambodian capital, which is located where three rivers—the Mekong, Tonle Sap, and Tonle Bassac—meet.

My hometown, Battambang, the largest province of Cambodia, is situated along the banks of the Sanke River, where the bustling downtown/provincial center serves as the hub of all activities. My family relocated to this central area after a bombing incident in our village. I have vivid memories of my middle school years when I would wake up early to attend physics tutoring class at 6 a.m. I rode my bike across the river and, on my way, would observe the villagers, fishers, and farmers transporting their fresh catch and produce on their boats to sell at the central market known as "Phsar Nat." Despite growing up in such a place, it never occurred to me how critical the river was to our lives. I took it for granted.

As I rode back home from my morning classes, I would occasionally spot kids joyfully plunging into the river for their afternoon bath and swim. I took my lunch break and a refreshing second bath with water transported from the river in a large container (if it was during the dry season). For lunch, I often had a serving or two of rice accompanied by one stew/soup dish and one grilled or fried dish. Our meals typically featured a fermented fish paste called "Prahok” with “Samlar Machu Pralit,” which is made of catfish and water lily. We use prahok in almost everything, similar to how cheese is used in Western cuisine. I didn’t think beyond the taste of the dish or if I was full—I didn’t think twice and that this fish and water lily came directly from the river, just as the rice was cultivated in the floodplain of the Tonle Sap Lake, which serves as the basin for the Sanke River. I took that for granted, too.

In the early evening, my friends and I would walk over to attend our English class located along the Sengke River. Along the riverbank, there were rows of food vendors selling various delicacies like Nom Pang Pate (baguette with pate and papaya pickles) and Lot Cha (short rice noodles fried with eggs and chives). We would often spot families, friends, and couples sitting and chatting while enjoying their post-school or work meals or snacks, recharging while releasing the day's stress. Some people would go for a walk or jog, while others would fly kites. Groups of boys would play shuttlecock kicking, and some would join the tae kwon do class, while some girls or women would participate in the dance class. All of these activities would happen along the river in the open air every evening. It never occurred to me how the river brought us peace, joy, and a sense of connection. I took it all for granted.

I took everything for granted until I had the opportunity to assist with research on the Tonle Sap Lake, the largest freshwater lake in Southeast Asia. I spent my days interviewing the villagers and fishers about their perspectives on the fishery resources in the lake and how their livelihoods depended on them. The stories they told were heartbreaking—of how abundant the fish used to be and how big the catches used to be. Nowadays, they have to venture farther from the village and spend more time fishing, but they still catch fewer and smaller fish. As they described the looming and degrading resources and the uncertain future, their faces grew sad. I couldn't help but wonder if their four or five children would be able to subsist if this trend continued.

This experience inspired me to pursue a master's degree in natural resources management, and I returned to conduct research on the lake. During my research, I discovered that there was a severe lack of information and research conducted on freshwater and fish ecology in the country where 70% of protein intake derives from fishery resources. This led me to pursue a Ph.D. in freshwater ecology, during which I happened to discover a new species of fish (Schistura diminuta) in the Sekong River—one of the major tributaries of the Mekong River which ranks third globally in terms of fish diversity. This discovery of new species emphasizes how little we know about the system.

During my fieldwork research on the floating village of Prek Toal on the Tonle Sap Lake, I witnessed firsthand the numerous challenges faced by the local community. In addition to struggling to find enough food, they also had to contend with waterborne illnesses and navigation difficulties caused by invasive plant species known as water hyacinths. On some occasions, I even observed large numbers of dead fish floating near the river or lake banks where nearby farms use fertilizers, resulting from eutrophication—the process where excessive nutrients in a body of water cause an overgrowth of algae, depleting oxygen and harming aquatic life. When I conducted my research on the Mekong River, I also noticed water marks on the houses, indicating high water levels during flash flooding caused by a dam operation upstream.

Amidst the struggles communities faced living in the Mekong and Tonle Sap basin systems, there are glimmers of hope. Last year, the rediscovery of a 100-pound and five-foot-long giant Mekong catfish and a 13-foot-long, 660-pound Mekong stingray made international headlines. These endangered species serve as a reminder of the incredible biodiversity that exists in these waters and the urgent need to protect them. We must act fast and give them the attention they deserve before it's too late.

As someone who has witnessed firsthand the degradation of these precious resources, I fear that my daughter, and all the children of Cambodia, will never have a chance to appreciate the abundance, beauty, and services of this system that once sustained us. It's time to come together and take action to protect freshwater ecosystems like the Tonle Sap and Mekong system for generations to come. Let’s not take them for granted!