Sea Stars Dying on Both US Coasts

Starfish are dying en masse from a wasting disease on the Atlantic and Pacific coasts. Researchers studying the die- off think it may be connected to warming ocean temperatures. The cause is yet unidentified and die-offs have occurred before but never of the same magnitude or wide geographic extent. Previous die-offs progressed in a predictable way and stopped spreading in winter. This is not the case in the new epidemic. This disease also affects more species of sea stars with twenty species susceptible and six highly vulnerable. It disease affects sea stars in the same way as stars are dessicated if they become trapped above the tidal zone, however, infected stars waste away in suitable habitat. The disease was first found in ochre stars (Pisaster ochraceus) along the Washington state coast. Wasting has been observed in Alaska, California, British Columbia and from New Jersey to Maine. A marine epidemiologist at Cornell University said the epidemic is the largest in the ocean he has experienced.

Sea stars are consider to be an indicator species of ocean health. The epidemic could therefore be a symptom of a much larger disequilibrium in ocean ecology. A publication from UC Santa Cruz says the current research emphasis is to identify a pathogen responsible for the disease. The publication uses bold letters to highlight the current scientific thinking that there is no evidence linking Fukushima radiation releases to the epidemic. Molecular sequencing of samples is underway at Cornell to identify possible viruses or bacteria as causative agents. Biologists know that warm water stresses marine organisms, making them susceptible to disease. Warm tidal pool temperature have been observed where sea stars are wasting away. A strong El Niño event is expected this winter which means more warmer sea temperatures. Scientists suspect that warm ocean temperatures intensify the spread of marine pathogens. Pathogenic impacts related to climate change have been observed in corals, shellfish, finfish, and humans.

The loss of an entire species such as ochre stars, which are formidable tidal zone predators can have wide-ranging ramifications for an ecosystem. In fact this was demonstrated by a famous experiment in marine ecology by Robert Paine at the University of Washington in 1963. He removed all of the ochre stars from a small area of rocky shore and observed to see what happened when all the stars were gone. Soon, mussels began to dominate the shore since they were no longer controlled by star predation. From this experiment the concept of a keystone species, the ability of an organism to shape its environment disproportionately to its own population, was introduced into ecological science.