Disease

The risk of a deadly disease is ever-present among wild populations, domesticated animals and even humans. It is a powerful ecological force, scientists say, often underestimated and under-researched.

Mist from the breath of killer whales is collected at the end of a long pole then tested for dozens of different types of bacteria. Photo: Pete Schroeder

OVERVIEW

Concerns rise over potential impacts of disease on the ecosystem

From orcas to starfish to humans, disease affects every living creature in the ecosystem. Scientists are increasingly alarmed by its potential to devastate already compromised populations of species in Puget Sound.  

RELATED ARTICLES

 Wild sockeye salmon in Adams River, BC. Photo: Province of British Columbia (CC BY-NC-ND 2.0) https://flic.kr/p/L6McUY
8/6/2020

Disease may play significant role in salmon declines

Few environment problems in the Salish Sea have been studied more than the steep decline in salmon populations. But one potential contributor to these declines has gained less attention. Scientists say infectious disease may play a wider role than previously understood.

Harbor Porpoise (Phocoena phocoena). Bellingham Bay, WA. Photo: Andrew Reding (CC BY-NC-ND 2.0)
7/9/2020

Fungal disease a rising concern for local marine mammals

A 2020 paper published in Frontiers in Marine Science describes details of the fungal disease Mucormycosis which has caused the death of harbor porpoises, harbor seals and one orca in Puget Sound in recent years. The authors discuss the implications for local marine mammals, specifically the endangered southern resident killer whale population.

Harbor seals. Photo: Mick Thompson (CC BY-NC 2.0)
5/18/2020

Causes of mortality in a harbor seal (Phoca vitulina) population at equilibrium

A 2020 article in the journal Frontiers in Marine Science looks at harbor seal stranding and necropsy findings in the San Juan Islands to assess age-related stranding trends and causes of mortality. The harbor seal (Phoca vitulina richardii) population in the Salish Sea has been at equilibrium since the mid-1990s. This stable population of marine mammals resides relatively close to shore near a large human population and offers a novel opportunity to evaluate whether disease acts in a density-dependent manner to limit population growth.

Beach closed sign. Photo: Washington Department of Ecology
4/9/2020

Pathogens Prevention Reduction and Control 5-6 (PC-00J88801) Final Report

The Pathogens Prevention Reduction and Control agreement between the Environmental Protection Agency and the Washington State Department of Health focuses on the prevention and reduction of pathogen pollution in Puget Sound through the management of human and animal waste. The primary objectives of the agreement include restoring shellfish growing areas, avoiding shellfish closures, and protecting people from disease.

Ocean Outbreak" cover courtesy of University of California Press.
3/17/2020

A conversation with "Ocean Outbreak" author Drew Harvell

When Cornell University ecologist Drew Harvell wrote her book "Ocean Outbreak," she couldn't have known that 2020 would be the year of COVID-19. But even as people around the world grapple with the effects of that disease, scientists are keeping watch on potential disasters from viruses and other pathogens for species in the world's oceans. As the oceans warm due to climate change, scientists expect incidences of disease to increase in marine ecosystems including the Salish Sea. We asked Harvell about her new book and the need to address this rising challenge.

Researchers led by veterinarian Pete Schroeder capture the breath of orcas in a search for pathogenic organisms from 2007 to 2009. // Photo courtesy of Pete Schroeder
3/10/2020

Virus related to measles could push Puget Sound orcas to extinction, study says

Researchers studying the killer whales that frequent Puget Sound are growing increasingly concerned that a dangerous virus or other disease-causing organism could spread through the population and hasten extinction of these critically endangered southern resident orcas.

Salmon smolts. Photo courtesy of Governor's Salmon Recovery Office
3/5/2020

Warming ocean conditions fuel viruses among species in the Salish Sea

As officials struggle to track and contain the outbreak of the novel coronavirus known as COVID-19, ecologists say widespread impacts from viruses and other pathogens are also a growing threat to the species of the Salish Sea ecosystem.

Rhinoceros auklets near Protection Island. Photo: Peter Hodum
12/6/2019

A health check for seabirds

Scientists are still trying to understand what caused the deaths of thousands of rhinoceros auklets in the Salish Sea in 2016. Some studies point to disease as a central factor in that incident and potentially other large seabird die-offs along the coast. That is prompting a deeper look at what makes these birds sick, and how local populations are faring. We followed a group of researchers as they gave a health checkup to a breeding colony of rhinoceros auklets on Protection Island.

Sunflower star (Pycnopodia helianthoides). Photo: JBrew (CC BY-SA 2.0) https://flic.kr/p/Jag9sr
3/14/2019

Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides)

The sunflower sea star (Pycnopodia helianthoides) is highly susceptible to sea star wasting disease. The authors of a 2019 paper published in Science Advances document the rapid, widespread decline of sunflower stars and discuss the ecological implications of losing this important subtidal predator species.

Clockwise from top left: 1) Mountain gorillas. Photo: Andries3 (CC BY-NC 2.0) https://www.flickr.com/photos/andriesoudshoorn 2) J pod Southern resident orcas – Photo: Miles Ritter (CC BY-NC-SA 2.0) https://www.flickr.com/photos/mrmritter/42903242165 3) Scientists collect orca breath samples. Photo: Pete Schroeder 4) Hawaiian monk seal. Photo: Karen Bryan/Hawaiian Institute of Marine Biology (CC BY-NC 2.0) https://www.flickr.com/photos/papahanaumokuakea/38322932854
3/13/2019

The Orca Docs: Can medical interventions help?

This three-part series explores opportunities and challenges of using medical interventions to save Puget Sound's southern resident orcas from extinction. Part 1 looks at how scientists might treat endangered southern resident orcas that face starvation and risks of disease; Part 2 considers how veterinarians have intervened with other animals in the wild, and how this might apply to orcas in Puget Sound; and Part 3 explores a federally approved vaccination program designed to ward of a deadly virus among endangered Hawaiian monk seals.

A Hawaiian monk seal at Papahānaumokuākea Marine National Monument. Photo by: Karen Bryan/Hawaiian Institute of Marine Biology (CC BY-NC 2.0) https://www.flickr.com/photos/papahanaumokuakea/38322932854
2/5/2019

Vaccines now used to reduce the risk of extinction in Hawaiian monk seals

For critically endangered animal populations, experts worry that a highly infectious disease could be the final nail in the coffin, forcing the species into extinction. That’s one reason why federal authorities approved the development and deployment of a new vaccine to ward off the deadly morbillivirus among Hawaiian monk seals. The vaccination program raises the possibility of using vaccines to prevent disease among Puget Sound's southern resident killer whales, but no specific steps have been taken so far.

Left: mountain gorillas. Photo: Andries3 (CC BY-NC 2.0) https://www.flickr.com/photos/andriesoudshoorn. Right: J pod southern resident orcas – Photo: Miles Ritter (CC BY-NC-SA 2.0) https://www.flickr.com/photos/mrmritter/42903242165
2/4/2019

Wildlife rescues may inform orca strategies

As the plight of Puget Sound’s southern resident orcas becomes increasingly desperate, with the population dropping from 98 to 75 in just 22 years, scientists are weighing the options of medical intervention. In part two of our two-part series The Orca Docs we look at how veterinarians have intervened with other animals in the wild, and how this might apply to the situation here in Puget Sound. [Part one, "When should medical experts intervene to save a killer whale?" is also available.]

Scientists in a boat use a long pole to capture the breath of an orca. Photo: Pete Schroeder
2/4/2019

When should medical experts intervene to save a killer whale?

The death of a young female orca in September has sparked a discussion of how and whether scientists should step in with medical care for distressed animals in the wild. Medical intervention has become routine for some endangered mammals, but scientists say Puget Sound’s resident orcas present a series of unique challenges and ethical questions. In part one of our two-part series The Orca Docs we look at how scientists are preparing to treat endangered southern resident orcas that face starvation and risks of disease.

Chinook salmon leaping at the Ballard Locks in Seattle. Photo: Ingrid Taylar (CC BY 2.0) https://www.flickr.com/photos/taylar/29739921130
7/16/2018

New studies on emerging threats to salmon

Chemicals, disease and other stressors can increase a salmon's chance of being eaten or reduce its ability to catch food. We wrap up our series on the Salish Sea Marine Survival Project with a look at some of the lesser-known, but still significant factors contributing to salmon declines in the Salish Sea.

A US Fish & Wildlife Atlantic employee displays an Atlantic Salmon with characteristic large black spots on the gill cover. Credit: Greg Thompson/USFWS (CC BY 2.0) https://www.flickr.com/photos/43322816@N08/9680675578
6/7/2018

Despite WA ban on farmed salmon, BC impacts may flow across border

A high-profile salmon escape led to a ban on salmon farms in Washington earlier this year. But just across the border, scientists say salmon farms in British Columbia expose migrating fish from Puget Sound to potential maladies like parasites, bacteria and dangerous viruses. They say simply getting rid of salmon farms in Washington does not put the potential impacts to rest. 

5/31/2018

Pathogens prevention reduction and control 1-4 (PC-00J32601): Final report

A report from the Washington State Department of Health outlines results from a series of projects funded by the U.S. Environmental Protection Agency's National Estuary Program in 2011. These projects addressed pathogen pollution in Puget Sound through the management of human and animal waste. Restoring shellfish growing areas, avoiding shellfish closures, and protecting people from disease served as the primary objectives.

Eelgrass at low tide. Photo by Olivia Graham.
5/18/2018

Diving deeper to understand eelgrass wasting disease

New studies show that eelgrass wasting disease is more common in warmer waters, leading to concerns over the future effects of climate change on eelgrass populations in Puget Sound. We continue our series on science findings from the 2018 Salish Sea Ecosystem Conference.  

Sunflower sea stars have all but disappeared from the Salish Sea due to sea star wasting disease. Photo courtesy of PLOS ONE
10/31/2016

Devastating transboundary impacts of sea star wasting disease on subtidal asteroids

A study in the journal PLOS ONE uses volunteer diver surveys to assess the impacts of sea star wasting disease in the Salish Sea. Data shows that sunflower sea stars were especially hard hit and have all but disappeared from the region. 

Toxic algal blooms are sometimes associated with invasive plankton. Photo: Eutrophication&Hypoxia (CC BY 2.0) https://www.flickr.com/photos/48722974@N07/5120831456
10/4/2016

Salish Sea snapshots: Invasive species and human health

Invasive species are considered a top threat to the balance of ecosystems worldwide. New discoveries of non-native green crabs in Puget Sound have highlighted that concern here at home, but invasive species can impact more than just the food web. Some introduced species can produce toxins that accumulate in shellfish or by directly infecting the human body.

Puget Sound Marine Waters 2015 report cover
9/27/2016

2015 Puget Sound Marine Waters Overview

The Puget Sound Ecosystem Monitoring Program released its fifth annual Marine Waters Overview this week. The report provides an assessment of marine conditions for the year 2015 and includes updates on water quality as well as status reports for select plankton, seabirds, fish and marine mammals.

Pathogen-free herring are reared from eggs to allow a wide range of experiments on infectious organisms at the Marrowstone Marine Field Station. Photo: Christopher Dunagan
1/13/2016

Disease in herring threatens broader food web

Pacific herring have long been considered an essential part of the Puget Sound food web. Now, studies are beginning to reveal how diseases in herring could be reverberating through the ecosystem, affecting creatures large and small. We continue our coverage of the ecological impacts of disease in Puget Sound with this look at the region's most well-known forage fish.

Steelhead (Oncorhynchus mykiss). Photo: Eric Engbretson, U.S. Fish and Wildlife Service
1/13/2016

Are diseases playing a role in salmon decline?

Chinook, coho and steelhead populations in Puget Sound have declined dramatically over the past 30 years. In some cases, counts of fish returning to the rivers are just a tenth what they were in the 1980s. While many possible causes of this decline are under consideration, some researchers are focusing on the combined effects of predators and disease. This article continues our coverage of the ecological impacts of disease in Puget Sound.

Purple sea star. Photo by brewbooks. Creative commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0).
12/3/2014

Virus associated with sea-star wasting disease

A virus is the likely cause of sea-star die-offs on the Northeast Pacific Coast and in Puget Sound, according to a November 2014 paper published in the Proceedings of the National Academy of Sciences.

Kelp crab on eelgrass. Photo courtesy NOAA Photo Library
3/10/2014

Host demography influences the prevalence and severity of eelgrass wasting disease

A paper in the February 2014 journal Diseases of Aquatic Organisms examines the effect of leaf age on wasting disease in eelgrass across sites in the San Juan Archipelago. Co-author: Encyclopedia of Puget Sound topic editor Joe Gaydos.