Benham Bank, located just off the eastern coast of Luzon in the Philippines. This mysterious underwater volcano is home to one of the most biodiverse and productive deep coral ecosystems in the entire Pacific. This natural wonder lies about 150 feet beneath the surface of the sea. It eclipses Mount Apo, the Philippines’ highest peak, in biodiversity and abundance of marine life. Findings from recent research expeditions have underscored its pristine waters and its unprecedented oceanographic characteristics, rendering this mid-oceanic region a critical sanctuary for marine biodiversity.
The North Equatorial Current significantly influences Benham Bank, potentially transporting larvae from various Pacific islands. This current continues strongly in the direction of the Philippines’ northeast coast, shown in purple. It then divides into two strong streams, the Kuroshio Current, flowing north, and the Mindanao Current, flowing south. These important ocean currents contribute to the productivity of one of the most vibrant and valuable ecosystems of marine life at Benham Bank.
An Ecosystem Teeming with Life
This means that Benham Bank is home to more than 60 species of reef-associated fish, according to Census research. Most of these species are commercially important food fish, such as large species of snappers, emperors, groupers, trevallies, and surgeonfishes. Many commercially important fish species call this incredible habitat home. So among them a rare vibrant community of butterflyfishes (Chaetodontidae) flourishes magnificently.
Since the most common fish seen on the reef were adults or large-sized individuals, this suggests a very stable and mature ecosystem. The upper 40-meter layer of the water column is a strong barrier. It keeps them from intermingling with older strata, forming a secluded habitat in which these fish can thrive.
“Seamounts, in general, are known for having high biodiversity and unique benthic (or seafloor) structures. Seamounts enhance ocean productivity and are considered biodiversity hotspots,” – researcher Joey P. Cabasan.
Clear Waters and Protected Habitats
One of the truly unique features of Benham Bank is its outstanding water clarity. This is why, according to Dr. Cesar Villanoy, one of the scientists involved in the research, low nutrient levels make for very nutrient-poor waters. As a result, this causes decreased chlorophyll levels in the water column. This consistency lets light reach deeper depths, supporting a thriving coral and algal population.
“The water at Benham Bank is very clear. Since there are no major sources of nutrients like large rivers, nutrients and chlorophyll in the water column are low, and light is able to penetrate to greater depths. This allows the corals and algae to thrive there,” – Dr. Cesar Villanoy.
The unique stratification of water layers at Benham Bank likely plays a role in protecting corals. Researcher Cabasan indicates that this biophysical stratification can shield the ecosystem from multiple stressors that largely plague marine environments.
“Benham Bank is in a way resilient to physical and thermal stress. There is stratification or layers with different water properties, which perhaps protected the Benham Bank from the effects of stress,” – researcher Cabasan.
Conservation Challenges
Even with their ecological importance, only 5% of seamounts globally—including the Benham Bank—are protected by some form of conservation measures. The still extremely limited protective measures, coupled with the very real threats of human encroachment and climate change, leave much alarm over the harm this delicate ecosystem might face.
Conservationists call for greater public awareness and protective measures to save Benham Bank’s unique biodiversity. Direct your newfound energy into collecting data on how costs and benefits of fishing practices, pollution, and climate change are changing. In turn, we can be confident that our underwater treasures flourish for future generations.