Adventures of a Crustacean Architect: LaGuardia Spat Collectors

My most recent posts are full of links and are lacking photos. This post will change that. Yesterday I went to LaGuardia Airport to collect and replace spat collectors, a monthly activity that I have been involved in since June. The spat collectors consist of bags of oyster shell that are tied to a rope and weighed down with a rock to serve as an anchor. There are two bags per rope and there are two ropes. Sadly we haven't found any spat, but we have found a variety of organisms living inside the bags and attached to the rope, which further supports the fact that oyster reefs do not only provide habitat for oysters but other organisms as well.

This is one of the ropes that the spat collectors were attached to. As you can see, it is completely encrusted with organisms, primarily hydroids. Hydroids are Cnidarians, so they are related to sea anenomes and can sting. It was so covered, the rope was difficult to pull up because it was slippery. We wore gloves to get a better grip and to avoid the hydroid's stinging cells.

Here is Eddie, an employee of the USDA who takes care of wildlife issues at the LaGuardia Airport. He is also a rock climber and has an extensive knowledge of knots, which came in handy in tying the oyster bags to the rope.

This is one of the spat collectors. It is completely covered with tunicates, which are also called sea squirts (because they can squirt water up to two feet) and sea grapes (because they appear, but do not taste like, grapes). They are highly tolerant of polluted water, which is probably why they are so numerous...

While I was waiting for the police to come open the gate for us, I noticed that there were oysters attached to the side of the boat launch. I have never been to this site when the water was so low, so I hadn't noticed them before. I had noticed that there were oyster shells washed up on shore, but when I asked the workers who repair the pier if they had ever seen an oyster attached to the pier, they said no. This is a huge find because there are currently only a few places in New York City where oysters have actually been documented.

I also found an oyster attached to the pier piling. Next time I go to LaGuardia, I'm going to try to go during a negative tide so that I can explore a little more to see how many oysters there actually are.

I brought the spat collectors back to the office so that I would have time to sort through them and look at all of the organisms that had hitched a ride. This is a mud crab. As you can see it is aptly named because it is covered in mud. It also has one claw that is bigger than the other. I'm guessing that this is a black fingered mud crab. They are predators of young bivalves, such as oysters and can crush shells that are less than 0.5 inches.

This is some kind of marine worm. I need to do more research because I don't know what it is but it looks very similar to an earth worm. I've found it in every spat collector so far.

Here is a close up of the sea grapes. They are filter feeders and suck in water though one siphon and their wastes out the other. You can see the two siphons on the sea grape to the left. You can also see their internal organs through their clear bodies. Tunicates are actually our closest invertebrate relatives. In their larval form they posess a notocord but lose it once the develop into adults.

There were also four eel-like fish that were unfortunately hiding in the spat collectors that I think are actually American eel. My next post is going to be devoted to them because they are a species of concern because it is disappearing at a rapid rate due to overfishing, habitat loss, pollution and blocked migration routes.

I had found a few of these eels in the spat collectors before but the pictures that I had taken of them were terrible because the office camera can't take pictures up close. I had thought that these eels were actually conger eels, but these eels short noses make that impossible.