The die-off of one of the most popular creatures that children like to see at the seashore, starfish, is still grinding on. But marine scientists still don’t have a firm handle on what’s causing it. But it appears that they might be getting there.
In an article published by a Hatfield Marine Science Center blog, the starfish die off may have been caused by a “one-two” punch from higher ocean water temperatures coupled with a commensurate rise in ocean acidity. Both higher acid and temperature levels are produced by human industrialization with its growing levels of greenhouse gases which are being absorbed by air the oceans of the world.
During a recent Hatfield Marine Science Center symposium, a gathering of marine biologists brought together information from lab testing and lots of fieldwork. They produced a consensus that although the suspicion might still focus on viruses and bacteria, they asked the question: What opened the door for them to get inside the starfish?
OSU Researcher Bruce Menge said rising ocean temperatures can lead to many oceanographic changes, among them higher acid levels in ocean waters which the west coast of the U.S. and many other countries are currently suffering. Oregon oysters have already begun showing the deteriorating effects of higher acid levels as they trying fruitlessly grow their shells off the Oregon Coast. Greenhouse gases absorbed by the oceans become a carbonate, which dissolves the calcium in developing shellfish.
In the same manner, starfish could be suffering from the deterioration of their outer layers which would make them struggle to maintain the proper balance of salt water in their bodies. As their outer layers fall away the (higher) acidic water could be attacking the starfish’s skeleton.
Another theory is that warming ocean water, with it’s higher acid levels, are severely stressing the starfish, causing their immune systems to weaken which invites harmful bacteria and viruses to do their worst.
Further studies on these and other variables are already underway. Scientists hope to report more progress in their pursuit of a cause, or set of causes, of the biggest starfish die off in modern history.
Starfish are a prime predator in intertidal areas along the coast. Starfish feed on sea urchins which generally feed on kelp. Without starfish, the population of sea urchins would dramatically increase, thereby increasing predation on kelp. Kelp is a primary source of refuge for fish as well as for sea lions and sea otters which are hunted by sharks and orcas. With a dwindling “forest of kelp,” the ecological balance of the near shore areas would likely be severely disrupted, say scientists.