Horseshoe crabs focus of trip Paddle on Bagaduce River provides insightful look at species

Posted June 03, 2006, at 2:55 p.m.
Last modified Sept. 01, 2011, at 2:56 p.m.

This column was first published June 3, 2006

 

 

Wonderful summer, wasn’t it? Actually, I thought it was a tad on the hot side, but at least it was dry.

Last weekend I got my on-water fix, squeezing in paddles on the Bagaduce River and Pushaw Lake. My return to the Bagaduce River above Bagaduce Falls in Brooksville coincided with the annual horseshoe crab mating ritual.

Friend and fellow paddler Karen Francoeur was guiding a tour for a Waterville family and she invited me along. I think this makes my third or fourth horseshoe crab trip, and each time I find it as interesting as the first.

The horseshoe crab is estimated to be at least 300 million years old. The earliest horseshoe crab species were crawling around the earth’s shallow coastal seas for at least 100 million years before the dinosaurs even arrived, about 200 million years ago.

This year, for the first time, I got to see a small one, about half again the size of a silver dollar. It was small enough to crawl around inside the overturned shell of an adult-size horseshoe crab.

The Bagaduce is about as far north as these prehistoric critters go to mate. A Web site I found lists Thomas Point Beach in Brunswick and Salt Bay and Hospital Cove in Damariscotta as two other places.

Here’s what I found on the Web that describes what’s happening during late spring on the horseshoe crab’s social calendar.

As the days lengthen, adult horseshoe crabs begin to move from deeper waters of the bay or continental shelf toward the beaches to spawn. Mating activity peaks during the full and new moons of late May and early June – that’s when the tides are the highest.

Adult males arrive on the beaches a few weeks before the females, and begin patrolling the near-shore waters for mates – sort of like the guys on Main Street here in Bangor atop their motorcycles.

When the females arrive, they release into the water a pheromone, a natural attractant that acts as a sexual stimulant. Horseshoe crabs also use their compound eyes to spot potential mates.

When they do (find a mate) the males hook their pedipalps (the specially modified second set of clawed appendages) onto the opisthosoma of a female as she heads toward the beach (make up your own visuals here, I had in mind the bar scene in “Star Wars”). Sometimes additional males will attach themselves to the male, forming a chain (I’m not going there).

Next the female drags the male to the water’s edge and once on shore, she uses her pusher legs to form a shallow nest between four and six inches deep between high- and low-tide lines. Here she deposits 5-7 clumps of 2,000-4,000 eggs each, or up to 20,000 eggs in a spawning episode. The attached male and any additional or satellite males that are surrounding the spawning female move with her as she lays each clump of eggs. She will repeat this process several times over the spawning cycle, laying 90,000 eggs or more in a season. It is estimated that fewer than 10 of these eggs will survive to adulthood.

The pair repeats this process several times before returning to the water. Scientists believe that on average female horseshoe crabs mature at 10-11 years and males at 8-9 years.

While this critter may seem insignificant, it has provided scientists insight into the function of our eyes – the result of studies that began more than 50 years ago on the large, compound eyes of the horseshoe crab. Its eyes have a relatively simple construction, and the optic nerve is readily accessible, according to the Web site.

Horseshoe crab blood, which is blue, is also valued. Here’s an abbreviated version of what I borrowed from the Web:

In the early 1950s, Dr. Frederick Bang discovered that its blood cells (called amoebocytes) contain a clotting agent that attaches to dangerous endotoxins produced by gram-negative bacteria.

When a crab is wounded, the amoebocytes swarm to the area and coagulate, forming a viscous gel surrounding the invading bacteria. Unable to escape, the bacteria are soon devoured by defense molecules such as antimicrobial proteins and polypeptides. This blood-clotting mechanism prevents infection from occurring in the horseshoe crab.

Bang realized this clotting agent could be used as a fast and accurate way to test pharmaceutical drugs for the presence of gram-negative bacteria. Up until then, drugs were tested by injecting rabbits with the drug and then waiting 48 hours to see if they developed a fever.

Within a few years of his initial discovery, Bang had created limulus amoebocyte lysate, or LAL, and a new method to test for gram-negative bacteria. It was so effective that the U.S. Food and Drug Administration accepted it as a standard test for endotoxins in 1983. Since then, LAL has gained widespread use, replacing rabbit tests for clinical and biomedical applications.

The FDA now requires an LAL test for injectable and intravenous drugs as well as for screening prosthetic devices such as heart valves or hip replacements. LAL is also used to diagnose spinal meningitis and other diseases.

And you thought these critters were good for nothing! Makes you want to go right down to the shore and give ‘em a big wet kiss, doesn’t it?

All this excitement about such an ancient crab sort of overwhelmed our paddle around a small island farther upstream that is home to a pair of nesting eagles. I never get tired of watching these magnificent birds. As we gave the island a wide berth, one of the birds flew toward shore where a flock of crows had gathered. Two of them took off after the eagle like fighter jets scrambling after an intruder and for five minutes put on an aerial dogfight before eventually breaking off to let the eagle soar alone.

Of life jackets and legislation

Sometimes the best intentions run headlong into a wall, or in this case off the end of the dock. It’s wondrous to me that civilization survived at least up to the 1950s without lawmakers protecting us from ourselves.

Take for example a bill (No. 4551) making its way through the Massachusetts Legislature that would make it mandatory for a person paddling a kayak at anytime to wear a U.S. Coast Guard-approved personal flotation device (Type I, II or III).

The bill is a combination of two separate pieces of legislation that were proposed by Rep. William Straus, D-Mattapoisett, and Rep. Shirley Gomes, R-Harwich. Both legislators began working on the issue following separate, fatal kayaking accidents in their districts.

Massachusetts law requires kayakers to wear life jackets from Sept. 15 through May 15. But if the bill wins approval paddlers, would have to wear them year-round while on the water.

In Maine, unless you’re 10 or under, you don’t have to wear a PFD in a kayak – you’re pretty stupid if you don’t, but there’s no law against stupidity – yet.

The proposal, which made it through the Massachusetts house, would also require a paddler to have a compass and a whistle, which is where (I think) things started to go haywire.

Then there’s another requirement that commercial kayak instructors obtain basic first aid training (CPR or a higher level of first responder qualification), and the American Canoe Association certification or equivalent training.

Another part that got Maine guides talking a week ago Thursday evening at the Maine Association of Sea Kayak Guides and Instructors meeting goes thusly: “All commercial … kayak instructors offering training to passengers or operators for hire shall provide training to each individual on the safety procedures appropriate to the level of paddling difficulty. Instruction of novices shall include actual wet exit training, so called, or any other practice in escaping from a kayak while submerged in a controlled water setting, pool or otherwise, before said individuals are allowed to use a kayak in open waters.”

If applied to every kayak tour here, guides mused, business would surely suffer. The intent, I think, was to mandate wet-exit training in all so-called classes but not in tours, but the bill’s sponsor never got back to me.

Some folks have their knickers in a twist over this legislation. They don’t want to be told what to do (think motorcycle headlight and helmet laws or seatbelt laws). Others think there’s a false sense of security in the requirement you wear a PFD – if you wear one you will be safe, with no regard to water conditions or temperature. For that matter, there’s no requirement for a dry suit or a wetsuit, or for the use of common sense or good training.

As for the whistle and compass, there’s a similar feeling that (1) they contribute to a false sense of security and (2) if one doesn’t know how to use a compass or know what direction to head for safety, there’s little good in having it in the first place.

Maybe a law requiring the use of a PFD isn’t the way to go. Maybe a law mandating boater safety courses is. I called Al Johnson, recreational boating safety specialist with the Coast Guard, to check out numbers of on-water fatalities in the First Coast Guard District (that includes all of New England). As I railed on about how fruitless I sometimes feel about safety seminars and preaching safety, he rattled off a few numbers.

In 2005 Maine had 16 boating fatalities (we have no mandatory boating education). Massachusetts had 10 boating fatalities (they have a limited boating education requirement). Connecticut had four, New Hampshire had one, Vermont and Rhode Island had none (they all have mandatory boating education). I guess there could be something said for mandating boater education, at least on the face of these numbers.

So in the name of education, I’ll pass along some more numbers for all you “Doubting Thomases” out there who scoff at wearing a PFD: According to the United States Coast Guard Boating Statistics report for year 2001, there were 101 deaths associated with canoes and kayaks. Of those, 93 percent (94 people) were due to drowning. The Coast Guard estimates that 84 percent (80 people) of them would have survived if they had been wearing a PFD (life jacket).

 

Jeff Strout’s column is published each Saturdays.

 

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