Filter Results

Oysters and eelgrass help each other out under increasing carbon dioxide levels

Increasing human output of carbon dioxide results in higher temperatures and in ocean acidification—the lowering of ocean pH and other chemical changes. Oysters are threatened by ocean acidification, while eelgrass may benefit from the higher carbon dioxide levels in the water. A new laboratory study asks whether culturing Pacific oysters (Crassostrea gigas) together with eelgrass (Zostera marina) can help both out. 

Read more

Intensive use of lake water affects freshwater food webs

Many lakes are important sources of water for agriculture and other purposes, while also supporting diverse ecosystems. In a new study, a comparison is made between the food webs of two natural lakes that were dammed early in the 20th century. The neighboring lakes are nearly identical except that one (Lake Keechelus) experiences rapid drawdown of water beginning early summer while the other (Lake Kachess) remains fuller and fluctuates less in water height during summer, but is lowered to a lesser extent beginning early fall. 

Read more

LIME: a new model for assessing the status of data-poor fisheries

Formal stock assessments are conducted for many large and valuable fisheries, but these typically require reliable catch data, estimates of trends in fish numbers, and age data from caught fish. In data-poor fisheries, these kinds of data are not available, resulting in difficulties in assessing whether they are overfished or sustainably fished. Now a new model called LIME has been developed that accounts for variability in recruitment (the number of baby fish produced each year), and can assess status from samples of the lengths of fish in each year, together with whatever additional information is available. 

Read more

Fish and chips: DNA analysis on a chip can separate endangered wild steelhead trout from hatchery steelhead trout

Many populations of native steelhead trout in the Pacific Northwest US are threatened by disease, habitat loss, poor ocean survival, and genetic mixing with hatchery steelhead trout. Steelhead are a form of rainbow trout that migrate out to the ocean when young, and return to spawn, just like many salmon species. Hatchery-produced steelhead have lower survival in the wild because they become less afraid of predators; one of the resulting concerns is that interbreeding between hatchery and wild steelhead will erode the natural fitness of wild steelhead and hinder their recovery. 

Read more

Steepness, lakes, and forest cover are the main factors influencing salmon-stream temperatures

Salmon returning to streams and lakes in Southeast Alaska are affected greatly by water temperatures both in winter and summer, and these temperatures are projected to increase given climate warming. Changes in water temperature affects the time it takes for salmon eggs to hatch and emerge, and the timing of salmon returning to each stream, as they seek to avoid dangerous peak stream temperatures. 

Read more

Traditional knowledge about polar bears adds to climate change evidence in Greenland

Interviews with 25 Inuit polar bear hunters in East Greenland provide a wealth of knowledge about changes in sea ice, warming, and polar bear distribution and trends. Evidence of climate change reported by the hunters included receding glaciers, higher temperatures, and the loss of sea ice. These changes made it harder for them to access sea ice, because dog sledges are no longer safe given wide patches of open water during months when sea ice used to be safe to travel over. 

Read more

Predicted impacts of ocean acidification on fisheries on the U.S. west coast

Ocean acidification is the a suite of chemical reactions in the ocean caused by climate change that include higher levels of carbon dioxide and lower pH levels, caused by human emissions of carbon dioxide into the atmosphere. A new model now projects the impacts of ocean acidification from California to Washington, finding that species declined most in the southern regions, but economic impacts were highest in the northern regions. 

Read more

Stretching out supplies of fish food to aquaculture species

Some types of aquaculture-raised (farmed) fish and crustaceans rely on wild-caught fish as feed for omega-3 fatty acids and micronutrients. But with the rapid and continuing rise of aquaculture, and the natural limits to the supply of forage fish (anchovies, herring, and their relatives), eventually this supply of feed will be exhausted. A new study now highlights ways in which the supply of fish food can be eked out further by: (1) reducing the proportion of feed that is based on wild-caught fish and switching to crop-based diets such as soy; (2) increasing catches of forage fish to maximum sustainable levels, adding 30% more catch compared to 2012 levels; (3) eliminating the addition of wild-caught feed to non-carnivorous farmed species; (4) eliminating forage fish from pig and poultry diets; (5) using trimmings from the processing of other wild-caught species as food for farmed fish; and (6) increasing the efficiency of farmed fish production. 

Read more

Substantial decline in polar bear range with sea ice loss

Polar bears rely heavily on sea ice to search for prey, and in Baffin Bay between Canada and Greenland, such ice-associated searching halts during ice-free months. However, since 1979, higher temperatures have resulted in the ice-free season in this region increasing by 12 days per decade in this region. Now, satellite-tags placed on 81 polar bears in Baffin Bay reveal that polar bears greatly reduced the area in which they forage between 1991-95 and 2009-15, by as much as 70% in summer. 

Read more

Centennial Story 19

Alexandre N. Zerbini (PhD, 2006)
It all started on a warm morning in the summer on the beach in my home country of Brazil when I was about 10 years old. I went for a walk with my father and three brothers when we came across a dead dolphin. It was a franciscana (scientifically known as Pontoporia blainvillei), one of the smallest cetaceans, and a species endemic to the western South Atlantic Ocean. 

Read more
Back to Top