Chesapeake Bay water quality declines by four percentage points
"An estimated 38% of the Chesapeake Bay and its tidal tributaries met clean water standards for clarity, oxygen and algae growth between 2016 and 2018. This score is lower than the record high 42% from the previous reporting period, but is still the fifth highest estimate of water quality standards attainment since 1985. This four percentage point decrease is due in large part to a decline in dissolved oxygen in the open waters of the Bay, those areas beyond the shoreline and shallows. Dissolved oxygen is necessary for the survival of the Bay’s aquatic species, and is a factor in the annual dead zone. [...]"
Uncovering diversity and metabolic spectrum of animals in dead zone sediments
"Ocean deoxygenation driven by global warming and eutrophication is a primary concern for marine life. Resistant animals may be present in dead zone sediments, however there is lack of information on their diversity and metabolism. Here we combined geochemistry, microscopy, and RNA-seq for estimating taxonomy and functionality of micrometazoans along an oxygen gradient in the largest dead zone in the world. [...]"
Source: Communications Biology
Authors: Elias Broman et al.
Fishing trawlers could harm water quality by disrupting seafloor microbes
Is there a technological solution to aquatic dead zones?
"Could pumping oxygen-rich surface water into the depths of lakes, estuaries, and coastal ocean waters help ameliorate dangerous dead zones? New work says yes, although they caution that further research would be needed to understand any possible side effects before implementing such an approach. [...]"
Source: Science Daily
Understanding Long Island Sound's 'dead zones'
"For the past 25 years, the Environmental Protection Agency and the Connecticut Department of Energy and Environmental Protection have been diligently collecting water samples each month in Long Island Sound (LIS). Recently, the data have been compiled and analyzed, by UConn associate professors of Marine Science Penny Vlahos and Michael Whitney, and other team members, who have begun the task of digging into the data to better understand the biogeochemistry of the Sound. Part of the analysis, called "Nitrogen Budgets for LIS," has been published in the journal Estuarine, Coastal and Shelf Science. [...]"
Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”
Climate models that do not account for anaerobic microbial activity may underestimate future expansion of oxygen-depleted waters.
"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]"
Warming climate will impact dead zones in Chesapeake Bay
"In recent years, scientists have projected increasingly large summer dead zones in the Chesapeake Bay, areas where there is little or no oxygen for living things like crabs and fish to thrive, even as long-term efforts to reduce nutrient pollution continue. Researchers factored in local impacts of climate change to make projections of what the oxygen content of the Chesapeake Bay will look like in the future. [...]"
Source: Science Daily
Large ‘dead zone’ measured in Gulf of Mexico
Hurricane Barry dampens initial size predictions
"This year’s Gulf of Mexico “dead zone”— an area of low oxygen that can kill fish and marine life — is approximately 6,952 square miles, according to NOAA-supported scientists. The measured size of the dead zone, also called the hypoxic zone, is the 8th largest in the 33-year record and exceeds the 5,770-square-mile average from the past five years. [...]"
Massive 8,000-mile 'dead zone' could be one of the gulf's largest
"JUST OFF THE coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history. Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose. [...]"
Source: National Geographic
NOAA forecasts very large ‘dead zone’ for Gulf of Mexico
"NOAA scientists are forecasting this summer’s Gulf of Mexico hypoxic zone or ‘dead zone’ – an area of low to no oxygen that can kill fish and other marine life – to be approximately 7,829 square miles, or roughly the size of Massachusetts. The annual prediction is based on U.S. Geological Survey river flow and nutrient data. [...]"