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49 posts in Research

Salmon face the opposing forces of fishing selection and natural selection

A 100-year simulation of individuals reveals the opposing forces that fisheries and natural selection play in sockeye salmon in Bristol Bay, Alaska. Natural selection favored the production of longer salmon, but also produced differences between the body type of salmon spawning in shallow streams (where body depth declined) and those spawning in the beaches of large lakes (where body depth increased). 

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Major implications for aquaculture production from the fast-growing science of epigenetics

The expression of DNA can be changed not only by changing the sequence of DNA letters, but also through epigenetics, which involves heritable changes in gene expression, for example by adding methyl groups to parts of the DNA. A new review delves deep into the implications of epigenetics for both fish and shellfish aquaculture to identify key areas of aquaculture where epigenetics could be applied. 

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Identifying fish species using DNA barcodes from multiple areas of DNA

A new method for identifying species from their DNA expands on current “DNA barcoding” methods. In the current DNA barcoding methods, a particular promising section of DNA in the mitochondria of cells is sequenced, and differences in the DNA “letters” used to identify species with high accuracy: for instance, this method is more than 80% accurate for freshwater fish species in the Congo River basin. 

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Selecting the best methods to measure ecological impacts of marine renewable energy

The environment may be altered by marine renewable energy developments, which include offshore wind turbines, surface wave converters, and tidal turbines. To measure their impact, it is crucial to first study pre-development conditions, but indicators tracking these conditions may include variability that can be above and beyond the ability of standard models to characterize. In a new paper, the performance of 13 different types of models is tested, with three particular methods performing well under different conditions: vector regression, random forests, and state-space models. 

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Nearly 400 million people are at higher risk of schistosomiasis because dams stop prawn migration

River prawns eat the snails that harbor schistosomiasis (also known as snail fever or bilharzia), acting as a natural control on the disease. Schistosomiasis is a disease in humans caused by parasitic flatworms, which causes chronic pain and stunted growth, diarrhea, and bloody urine, and if left untreated, liver and kidney failure, infertility, and bladder cancer. The parasite infects river snails, which pass the parasites to humans when they come into contact with water containing the parasites. 

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Some beluga whales are leaving the Arctic later because of changes in sea ice

Some Arctic beluga whales now leave the Arctic 2-4 weeks later because of delayed sea ice formation there. The change happens because the southward migration of beluga whales from the Eastern Chukchi Sea population through to the Bering Sea is determined largely by the date of sea ice formation in the Arctic areas north of Alaska, and sea ice formation is happening later in the year. 

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How to balance food and energy with hydropower dams

Almost 100 hydropower dams are planned on the 2700 mile Mekong River, which is a huge economic driving force and a food source for millions living in Burma, China, Vietnam, Laos, Thailand and Cambodia. While these dams will supply much-needed electricity, they will change the flow patterns on the river, which could impact businesses and food security from fisheries. New research now shows how to solve this tradeoff: regulate water releases from the dams so that there are long periods of low water flow interspersed with pulses of flooding. 

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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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