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179 posts in Publications

More abalone succumb to withering syndrome disease at higher temperatures

Withering syndrome is a disease that strikes abalone species throughout the Northeast Pacific Ocean, and is one of the main drivers of recent population declines. This disease is long-term and chronic and is caused by an infection inside the cells of abalone of tiny bacteria in the order Rickettsiales. A new study examines how three abalone species react to withering syndrome infections at different temperature, finding that cool-water pinto abalone succumb at the lowest temperature (17.3°C), red abalone at an intermediate temperature (18.0°C), and warm-water pink abalone at higher temperatures (18.8°C). 

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Measuring surprising booms and busts in animal numbers

Black swan events are highly improbable events that nevertheless occur, and drive risk estimation in stock market collapses, earthquake frequency, and deaths from the largest wars. But how often do animal populations exhibit surprisingly large booms and busts? A new study finds strong evidence for black swan events in about 4% of animal populations, typically driven by climate, severe winters, predators and parasites. 

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Human changes to the natural flow of rivers results in simplified plant networks

The natural pattern of river flows, with frequent flood events, has been substantially altered worldwide through dams and other forms of water diversion for human uses. A new modeling study now shows that changing historical flow patterns results in simplified interactions between plant species in and around rivers, and the replacement of large riverside trees with shrubs. These changes to plant species are influenced by the loss of frequent floods, increased droughts, and a river flow pattern that is more stable than is normal. 

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Oyster transplants reveal hidden diversity among native oysters

Native oysters are important players in many nearshore ocean ecosystems, but their numbers are declining worldwide. Restoration success depends on how well oysters survive when transplanted to new habitats. In a new experiment, native Olympia oysters were transplanted among oyster regions in Puget Sound in a reciprocal fashion to see how this affected their survival, growth, and reproduction. There were substantial differences in each small population of Olympia oysters within Puget Sound, providing information on which source population would be best suited for broad-scale oyster restoration in the region. 

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How uncertain are fisheries stock assessments?

Fish catch limits are set based on the results of complex fisheries stock assessment models, which are somewhat like weather forecast models, but for fish populations. An examination of historical assessments of Australian fisheries has determined that there is considerable uncertainty in estimates of fish biomass, with a 95% chance that stock assessment estimates of spawning biomass are within half to double of the best estimates. 

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Endangered whooping cranes start dating long before the kids come along

Endangered whooping cranes form long-term monogamous bonds, but it has not previously been known when these pair bonds first form. New data now reveals that 62% of breeding pairs actually form more than a full year before breeding, and 28% of breeding pairs begin to “date” more than two years before breeding starts. These findings suggest there are substantial benefits to partnering in addition to breeding, perhaps to support each other when competing with other birds or to increase partner familiarity. 

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Annual flooding in Cambodia opens up new food resources for fish

The Tonle Sap Lake in Cambodia is a seasonal wetland that floods every year during the rainy season. New research examining the isotope ratios in carbon, sulfur, and nitrogen in fish, shows that fish species benefit greatly from this flooding because it expands their access to new and different types of food contained in the newly flooded areas. The resulting highly diverse assemblage of fish species are the basis of a productive fishery that is a major provider of food in the region, which will be impacted in uncertain ways by the planned construction of more than 200 dams in the greater Mekong River Basin that feeds Tonle Sap Lake. 

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Cooler rivers and dam avoidance help Chinook salmon survive better when migrating to the sea

Chinook salmon on the Snake and Columbia rivers face challenges, notably navigating through hydropower systems, during their migration from freshwater to the ocean; these experiences may change their survival in the ocean. A recent laboratory experiment compared Chinook salmon that were barged through five or seven dams (experiencing cooler temperatures) to those that swim through the hydropower system (experiencing warmer temperatures). 

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Baby salmon emerge from gravel earlier and less developed when temperatures are warmer

A new series of laboratory experiments on Chinook salmon reveals the effect of warmer freshwater on the time from egg hatching to emergence from gravel as fry. Warmer water resulted in fry emerging two and a half months earlier than those exposed to cooler water, after accounting for genetic differences among eggs produced by different combinations of parental fish. The newly emerged fry were also less developed on emergence when exposed to warm water. 

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Places that beluga whales like in the Arctic are not closely linked to ice conditions

A new study uses two decades of tagging data on beluga whales to identify habitats that they prefer. In the eastern Chukchi and eastern Beaufort Seas, belugas preferred places with particular depth features, like canyons and continental slopes, instead of preferring places based on sea ice characteristics. Thus while reduced sea ice in this region may indirectly affect belugas through ecosystem changes, they did not rely on sea ice features to find places with good food availability. 

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