Biologists have counted 43 species of fish near underwater asphalt volcanoes

Scientists have studied the fauna of the asphalt volcanoes of the Santa Barbara Strait. Reported by the University of California at Santa Barbara.

Asphalt volcanoes are natural vents of oil from the Santa Barbara Strait off the coast of California. They create a lot of problems for beach lovers, because they cover the coast with dark spots, but they also give rise to a unique ecological environment about which biologists know almost nothing.

Milton Love and his colleagues decided to characterize the fish communities that inhabit these unusual objects. Their goal was to find out who lives where and why. To do this, the authors used a remotely controlled underwater vehicle, with which eight hours of observations were made and 2743 still images were taken. Although the density of the fish was low, its species were diverse. In total, the authors observed 1836 fish representing at least 43 species. At least 53.5% of these species were groupers. “This is what you would expect to find when looking at a high and fairly smooth rocky reef in this region,” Love said.

Some fish enjoyed the uniform slopes of volcanoes, including groupers like the green-spotted Sebastes ensifer . Meanwhile, the muddy seabed that surrounded the underwater hills was inhabited by a variety of sea chanterelles and flounders. Oddly enough, flounder-free haloes a few meters wide formed around the volcanoes. Love suspects that those fish that dared to get too close were seen against the black tar and eaten.

The researchers observed several taxa of fish moving between the silt and asphalt, including greenlings, greenband groupers and American hydrolags. However, “even a small amount of asphalt in the image had a significant impact on the observed species,” the authors write, as fish living on the soft seabed stayed away from the hard tar.