Dissolving Sea Stars Reveal a Damaged Ocean
Lynn Wilson, is Academic Department Chair for Public Administration at Kaplan University and founder and CEO of the SeaTrust Institute. A science journalist and academic author, Wilson is also a delegate for the United Nations Framework Convention on Climate Change and other United Nations regimes, a reviewer for the U.S. National Institutes of Health and the IPCC, and an active researcher with projects in Africa and the Pacific Islands. She contributed this article to Live Science's Expert Voices: Op-Ed & Insights.
On a remote Pacific Northwest beach, the intertidal world reveals itself to the air breathers. Mussels and gooseneck barnacles fasten to exposed rocks that shelter the apex predators: ochre sea stars (Pisaster ochraceus). But something is wrong. White spots spread across the stars' disintegrating arms, and instead of regrowing the damaged appendages as sea stars often do, the entire animal rapidly dissolves into a mass of goo.
First noticed in Washington state in 2013, "sea star wasting disease" reached alarming proportions by July 2014, its cause unknown — even though the disease was first identified in 1979.
Beginning in June 2014, local researchers from SeaTrust Institute investigated relationships between marine diseases and human health. They encountered significant numbers of the disintegrating echinoderms along coastlines and throughout the Salish Sea straddling the border of British Columbia and Washington state. The disease was of particular interest to the team because Pisaster ochraceus is considered a keystone species, with disproportionately large influence on maintaining local species diversity by keeping certain grazers in check and feeding on the mussel Mytilus californianus. [In Photos: Sick Sea Stars Turn to Goo]
Cornell University epidemiologist Drew Harvell suspected a bacterium or a virus was causing the condition, and by November 2014, Cornell microbiologist Ian Hewson identified the source as the parvovirus Sea Star Associated Densovirus (SSaDV). This provided sufficient scientific evidence for the local researchers to weave the story of the sea stars and ocean health into the broader conversation about human health, climate change and sustainability. They did this at the December global climate change negotiations at the United Nations Framework Convention on Climate Change.
SSaDV is not considered harmful to humans who eat shellfish or come in contact with affected seawater (two pints of clear seawater contains more than 4 billion viruses), but this unfolding story points to deeper connections between ocean health and human health. Fifty experts at the 2014 Oceans and Human Health Conference made a unanimous appeal for "coordinated, transnational and interdisciplinary oceans and human health research" illuminating the rising stakes in a warming world.
Ocean health mirrors global human health
Healthy oceans provide vital ecosystem services including primary production: the photosynthetic conversion of energy to organic substances by phytoplankton and other organisms.
Such habitats also provide coastal protection, waste remediation and recreation. Ocean-sourced nutraceuticals, biofuels, drugs and industrial products fuel economies and lead to medical breakthroughs.
Marine tourism, blue energy (tidal power, wave power, wind power), aquaculture and marine mineral resources contribute to human well-being through jobs and economies, as well as through energy and food. The November 2014 Rome Declaration on Nutrition by the World Health Organization and the Food and Agriculture Organization emphasizes the role of oceans in an increasingly food-insecure world.
Unhealthy oceans have the opposite affect on human health . Pollution and plastics affect marine health and biological reproduction, while biodiversity loss stresses habitats and population resilience.
Countries dump effluents from industries and cities off their shores, and in some cases, poor nations take financial compensation to dump the toxic waste from other nations who can afford to pay.
Diseases and pathogens like harmful algal blooms, parasites, bacteria, viruses and invasive species pose biological hazards to humans through contact, food or water contamination, and respiratory irritation. That can include the effects attributed to Karenia brevis, a particularly toxic red tide with an airborne neurotoxin found in the Gulf of Mexico. Warmer seawater is less salty, favoring Vibrio infections such as cholera and gastroenteritis.
Rising ocean temperatures contribute to extreme weather events causing injuries and deaths from stronger and more frequent storms. These include Midwestern tornadoes or less-frequent but more damaging cyclones, like the 2015 storm that devastated the island nation of Vanuatu. Warming seas accelerate sea level rise through thermal expansion and contributions to Antarctic and Greenland ice-sheet melting. These effects are exacerbated by coastal subsidence and wetlands sediment deprivation from dams, irrigation, aquifer depletion and the redirection of watercourses.
Ocean chemistry is also changing. Acidification favors jellies, but threatens species that depend upon calciferous shell and skeletal formation. These species include planktonic pteropods, coccolithophores and foraminifera, as well as corals, snails, clams, mussels, oysters, crustaceans, sea urchins and coralline algae.
Coccolithophores — a group of algae phytoplankton that secrete calcareous skeletons — are credited with producing nearly half of the oxygen humans breathe on a daily basis, and when compromised, these organisms become food for viruses. The upwelling of stagnant deep water and nutrient-rich agricultural runoff contribute to expanding dead zones where low oxygen levels threaten marine life. Scientists like Stanford University's Stephen Palumbi speculate that warming temperatures may cause entire food webs to rearrange.
As Pacific Northwest researchers and citizens count juvenile sea stars, they watch for signs of disease and speculate about SSaDV's relationship to high seabird mortality or its potential to infect other species including urchins. They also wonder if this is an early warning about pathogen development throughout global seas.
If the fate of these sea stars is related to declining ocean health, that portends other disease outbreaks with ramifications for human health. Identifying and monitoring the multifaceted and interconnected aspects of potential events deserves strong attention at local and global levels.
Loss of an apex predator could trigger a trophic cascade (when predators are eliminated, ecosystems destabilize, setting off chain reactions that harm biodiversity). That would alter the balance of predator and prey species, resulting in less-sustainable fisheries, loss of species diversity, and other radical alterations in marine ecosystems.
Human health depends upon ocean health, and it may be that at least part of this complex story is written in the stars.
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