New fish of underwater asphalt volcanoes

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

Asphalt volcanoes are natural oil outlets of the Santa Barbara Strait off the coast of California. They create a lot of problems for beach lovers, because they cover the shore with dark spots, but at the same time they also generate a unique ecological environment, about which biologists know almost nothing.

Milton Love and his colleagues decided to characterize the fish communities inhabiting these unusual objects. Their goal was to find out who lives where and why. To do this, the authors used a remotely operated underwater vehicle, with which eight hours of observations were carried out and 2,743 still images were taken. Although the density of fish was low, its species were diverse. In total, the authors observed 1,836 fish representing at least 43 species. At least 53.5% of these species were sea bass.

“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 liked the homogeneous slopes of volcanoes, including sea bass like the green-spotted Sebastes ensifer. Meanwhile, the muddy seabed surrounding the underwater hills was populated by a variety of sea chanterelles and flounders.

Oddly enough, halos several meters wide were formed around volcanoes free of flounders. Love suspects that those fish that ventured too close were spotted against a background of black resin and eaten. The researchers observed several taxa of fish that moved between silt and asphalt, including terpugas, green-banded 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, since fish living on the soft seabed stayed away from the hard resin.