(Photo/Andrew Easton, 2004)
Every year the horseshoe crabs gather to spawn, releasing thousands of eggs along the Delaware Bay coast. And with timing perfected by evolution, red knots, a bird enduring one of the most impressive yearly migrations from the Arctic to the Tierra del Fuego, arrive just in time to gorge on the eggs of the horseshoe crab. It is a vital stop on the “peeps'” spring migration. But the crabs and their eggs are disappearing, a loss with dire consequences for the little birds.
Red knot populations have fallen more than 75 percent in recent years, and new research published in this month’s issue of Bioscience reveals that Red knots can thank the bait fisheries for their hungry stomachs. Within half a decade the fisheries harvesting horseshoe crabs grew 20-fold, gobbling up more than 2 million crabs a year and effectively eliminating 90 percent of the eggs that red knots rely upon to survive their almost 19,000 mile migration.
But this research is not just a blame game for the fisheries. A coalition of scientists worked together on this study to help draft recommendations for the adaptive management of the bait fisheries that could help all three groups survive.
For a month after birth, Southern right whale mothers and their calves rest and nurse. Then, like the pair shown here off Argentina, they start to swim faster and farther as they prepare for a long migration in the South Atlantic to reach their feeding areas. A University of Utah study found mother whales teach their calves where to eat, raising concern about whether the whales can adapt as global warming disrupts feeding grounds. (Photo/John Atkinson, Ocean Alliance)
Mom right whales know best when it comes to mealtime it seems. They lead calves to grub at traditional feeding grounds teaching their offspring generations of knowledge about when and where to find food. In fact whole clans of whales will dine together in the cetacean version of a family-owned dining spot. But this is one family tradition that could lead to starvation for an already vulnerable whale species if climate change causes shifts in food distribution.
Previous research by Vicky Rowntree, research associate professor of biology and a coauthor of the new study at the University of Utah, has already shown the impacts of climate change on right whale populations. When sea temperatures rise, krill disappear and right whales respond by giving birth to fewer offspring. Now these new studies into whale behavior could highlight another problem for the whales when it comes to food.
“A primary concern is, what are whales going to do with global warming, which may change the location and abundance of their prey?” asked Rowntree in a press release. “Can they adapt if they learn from their mother where to feed – or will they die?”
Rowntree and her colleagues collected skin samples from right whales and, using a novel technique in science, combined DNA and isotope analysis to determine whale lineages and where they tend to chow down. They found that related whales congregated in designated areas to feed, and that mothers teach calves in their first year of life where to find food.
Here’s to hoping that right whales will be quick to adapt if the buffet moves elsewhere.