Monday, May 14, 2012

Ancient history renews itself on Raritan Bay

Usually I'm pretty single-minded when I'm traveling to or from Sandy Hook: it's a non-stop trip from home to the Hook, or vice versa, interrupted only by a stop for gas or maybe a custard cone. Yesterday, however, Ivan had other ideas as we made our way home after a productive birding excursion. 

"Let's stop on the bay," he said. "There's some good shorebird habitat there, and maybe we'll run into something else." 

"Something else" is usually a historic spot or a notable sign or something. This time it wasn't. Once we parked the car near a newish townhouse development, Ivan led the way along a sandy dirt path until we reached the waterline. On one side was the bay, with a nice tract of spartina being flooded by the incoming tide. On the other was the mouth of a small creek, edged by a dirt/sand mixture of shoreline. I was a bit birded out for the day, so I focused on what was moving around in the water. There was plenty to watch!

We'd arrived just in time for the start of the daily horseshoe crab spawning. In a routine that's gone on for more than 500 million years, the females glide up to the area between low and high-water levels to lay their eggs, followed by a host of males that fertilize them. Check out the brief video I recorded, showing how quickly the seemingly lumbering animals move to lay their eggs. (You may want to shield the children, as there is graphic arthropod mating action going on here.)


One mistake I made on the narration: horseshoe crabs aren't as plentiful as we need or would like due to overharvesting. They're actually quite popular for use as bait in the eel and conch fishing industries, plus their blood has certain benefits for use in medicines for humans. While they can be effectively bled and then returned to their customary habitat, the bleeding process has a horseshoe crab mortality rate of 10 to 15 percent.

Raritan Bay shorebirds will likely enjoy some of the eggs we saw being laid, but the acute need for horseshoe crab spawn is on the shores of Delaware Bay. Hundreds of thousands of migrant birds, including the threatened red knot, customarily land on the beaches looking for their first meal after a long journey. Without horseshoe crab eggs to count on, it's likely that many of them would die of starvation. Thus, organizations like New Jersey Audubon have been sounding the call for conservation and protection of these prehistoric animals. They may not look especially attractive, but they're a crucial link in our ecosystem.

If you happen to be on the beach around high tide, keep an eye out for these ancient helmet-shaped creatures. You'll get a biology lesson you won't soon forget. I know I won't.

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