By Beth Sullivan
What is it about moonlight that tugs at tides and hearts and horseshoe crabs?
The full moon has pulled at the Earth’s waters since the beginning of time. Creatures living in the ocean most certainly have responded and adapted to those tugs. People living near the sea are finely tuned into the changes in the tides. They know without consulting charts and apps when the tides will be full and what phase the moon is in.
|Sunset from the island. Photograph by Mark Hibbard.|
This past weekend the moon and sun and tides were in a unique situation, coming together in a way that doesn’t happen often. Monday was the Summer Solstice, the longest day of the year. As the sun set beautifully in the West, a turn of the head revealed the huge Full Strawberry Moon rising in the East, within minutes. The tide was rising to full, and the Horseshoe crabs were following their ancient instincts to seek sandy shallows to mate and lay eggs.
|All efforts are made to tag and measure the crabs while they remain close together. Photograph by Mark Hibbard.|
A few of us were lucky enough to be out during this cycle and appreciate the beauty and mystery of the ritual that has gone on for millions of years. As long as there has been a spit of sand that is Napatree Point, which gave birth to Sandy Point, the crabs have sought out this protected place.
In an effort to understand the life cycles, needs and drastic decline of the horseshoe crab population, Project Limulus has been studying these creatures by supporting teams which scout the shoreline along Long Island Sound to observe, count and tag the crabs. Volunteers are taught to measure and assess the condition of each crab encountered. Tags are to be placed in a specific area on the shell. On this night we were treated to a motorized ride out to the eastern end of the island. We usually paddle out, which certainly is fun, but this was a luxury. It was calm and beautiful.
Usually there is the greatest “action” on the protected north shore of Sandy Point. The crabs seem to seek out the quieter waters and gently sloping beach to make their nests. There were not many to be found. We did however get to observe two Piping Plovers which have protected exclosures over their nests. We also were met by the loud cries of several families of American Oystercatchers which are having a great success out there this year.
|The Oystercatchers greeted us with lots of noise. Photograph by Rick Newton.|
|The Piping Plivers still struggle to nest successfully on Sandy Point. Photograph by Victoria Limi.|
At the far east end, we were beginning to be discouraged, all that walking and effort for virtually no crabs. However, as we rounded the point and headed along the south shore, the current increased; there was more wave action, and hundreds of crabs.
Horseshoe Crabs on the beach
As far as we could see down the beach there were mounds at the waterline, each indicating a nesting pair. As we walked toward the first, we could see even more off shore, some already dug into the sand, in a couple of feet of water, others moving toward shore. There were many “piles” with one large female surrounded by as many as 4 smaller males, jockeying for the best positions.
|Larger females are often joined by several smaller males as she digs a nest. Photograph by Tom Frohnapfelw.|
The males usually try to connect with a female farther off shore and they will land together so that as she digs into a nest in the sand, he will be in the best position to fertilize her eggs as she lays them.
|On this night, the crabs didn't seem to mind the waves. Photograph by Rick Newton.|
We only had 100 tags to use. We used them all in a relatively short time, and there were still more crabs coming into the shore. We were tired; it takes a bit of muscle to manage the crabs, tools and equipment while bending into the water. It was getting late, and the tide was turning. We left the rest of them to nest in peace.
|The Strawberry moon rose over Watch Hill. Photograph by Ingrid Fedderson.|
Sunset, Full moon and the tides tug on more than just the horseshoe crabs.