DAVID NIELD
17 JAN 2020
Scientists have reported on another devastating biological disaster, caused by a patch of abnormally warm water in the Pacific Ocean known as 'the Blob'.
This concentrated marine heatwave lingered in the northeast Pacific between 2013 and 2016, and researchers now think it was largely responsible for the death of almost a million common murres (Uria aalge), amongst other wildlife. This makes it the largest seabird die-off in recorded history.
The estimate is based on some 62,000 murres that washed ashore on the west coast of the US during 2015 and 2016, covering an area stretching from California to Alaska. Only a fraction of birds that die at sea typically wash ashore, indicating the scale of the mass dying was much larger than the number of bodies we've found.
The emaciated birds were left starved by a lack of food, caused by increased competition in the warmer waters, according to the scientists – and numerous other species may have been hit by the same confluence of factors.
"Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often," says biologist Julia Parrish, from the University of Washington.
"We believe that the smoking gun for common murres – beyond the marine heat wave itself – was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock and Pacific cod greatly increased."
The team reviewed studies of fish and plankton collected by fisheries during the time the blob was at its peak, as well as other field studies and reports, and concluded that the warmer temperatures in the water had increased the metabolism of these cold-blooded ocean dwellers.
Continued
17 JAN 2020
Scientists have reported on another devastating biological disaster, caused by a patch of abnormally warm water in the Pacific Ocean known as 'the Blob'.
This concentrated marine heatwave lingered in the northeast Pacific between 2013 and 2016, and researchers now think it was largely responsible for the death of almost a million common murres (Uria aalge), amongst other wildlife. This makes it the largest seabird die-off in recorded history.
The estimate is based on some 62,000 murres that washed ashore on the west coast of the US during 2015 and 2016, covering an area stretching from California to Alaska. Only a fraction of birds that die at sea typically wash ashore, indicating the scale of the mass dying was much larger than the number of bodies we've found.
The emaciated birds were left starved by a lack of food, caused by increased competition in the warmer waters, according to the scientists – and numerous other species may have been hit by the same confluence of factors.
"Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often," says biologist Julia Parrish, from the University of Washington.
"We believe that the smoking gun for common murres – beyond the marine heat wave itself – was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock and Pacific cod greatly increased."
The team reviewed studies of fish and plankton collected by fisheries during the time the blob was at its peak, as well as other field studies and reports, and concluded that the warmer temperatures in the water had increased the metabolism of these cold-blooded ocean dwellers.
Continued
