Seashells from an island next to Manhattan
What could possibly wash up on (be found live on) the shore of the Harlem River (right in the heart of New York City, one of the most urban areas in the world) that would be of considerable interest to naturalists?
I naively assumed there would be very little at all. But I was wrong!
First I should explain that the Harlem "River" is not actually a river -- it is a tidal inlet, and so is the East "River". They are both part of the complex geography of the estuary of the Hudson River. Thus the Harlem River is saltwater, not freshwater, but the water may almost never be at full seawater salinity, because it is an estuarine environment.
On Randall's Island Park during low tide, there is a very small sand beach on the Harlem River. There is usually some beach drift there, and it is quite interesting. So far I have found three crab species, a jellyfish species, a comb jelly, and various species of green, brown, and red algae.
With a lot of careful and thorough searching over a number of visits, I /we have also managed to find a surprising number of marine mollusk species, including four live species and quite a few fresh-dead shells in good condition.
The species I have found so far are listed here, in decreasing order of commoness.
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BIVALVES
Softshell Clam -- Mya arenaria, including small live individuals
Atlantic Jacknife -- Ensis directus, many fresh paired valves in good condition
Dwarf Mulinia -- Mulinia lateralis", many single valves
Baltic Macoma -- *Macoma petaluma , some paired valves
Eastern Oyster -- Crassostrea virginica, single valves, fairly common.live ones at low tide
Atlantic Ribbed Mussel -- Geukensia demissa, a few sets of paired valves, several single valves
Atlantic Rangia -- Rangia cuneata, single valves, AN INTERESTING ESTUARINE SPECIES!
Hard Clam -- Mercenaria mercenaria, one live juvenile, some broken pieces of adults
Blue Mussel -- Mytilus edulis, two valves
GASTROPODS
Eastern Mudsnail -- Tritia obsoleta including three or four live ones, and a lot of empty shells. Also eggs of this species laid on red algae.
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June 3rd 2017, I found:
MORE GASTROPODS!
Shark Eye -- Neverita duplicata -- one broken shell
Eastern White Slippersnail -- Crepidula plana, live inside the Shark Eye shell
And a few days ago on June 1st I found these small, white, very fragile shells, each of them as a complete shell with paired valves:
MORE BIVALVES!
Northern Dwarf-tellin -- Ameritella agilis (formerly Tellina agilis)
Glassy Lyonsia -- Lyonsia hyalina (by June 18th a total of three intact shells)
Shining Macoma -- Macoma tenta (only one so far)
These three species are very surprising for such an urban locality, the Shining Macoma being the biggest surprise of all, as this species was thought to be very particular about where it lives, and it is usually only found far out on Long Island where there is very little pollution.
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Observaciones
Fotos / Sonidos
Observ.
susanhewittDescripción
Because on this beach I have seen quite a lot of shells of Mya arenaria which have a neat hole drilled in them, I was expecting at some point to find the shell of a moon snail.
This shell is fairly fresh but very broken -- presumably the snail was eaten by a large crab or a strong-jawed fish.
Fotos / Sonidos
Qué
Mya arenariaObserv.
susanhewittDescripción
The valve on the left was drilled by a moon snail.
Fotos / Sonidos
Qué
Crepidula planaObserv.
susanhewittDescripción
In the lower part of this photo.
A very tiny live juvenile on the inner surface of the broken shell of Neverita duplicata.
That might tend to suggest that the moon snail shell was inhabited by a hermit crab before the shell was broken and the contents eaten by a predator.
Fotos / Sonidos
Observ.
susanhewittDescripción
I took this red alga home to photograph it better, and I was amazed to see that it had several rows of tiny eggs attached to it.
They are very tiny, only about 2 mm across. They look identical to the egg masses of this species.
I photographed them in the water and out of the water too.
Fotos / Sonidos
Qué
Mya arenariaObserv.
susanhewittDescripción
Two tiny live Mya arenaria clams. I put them back of course.
Fotos / Sonidos
Observ.
susanhewittDescripción
A tiny live example of Mercenaria mercenaria -- I put it back of course.
Fotos / Sonidos
Observ.
susanhewittDescripción
This observation is for the upper shell -- the pink rayed tellin, not the all-white one at the bottom, which is Ameritella agilis.
The pink shell is a little more than 6 mm in length.
These two tellin shells were photographed while they were still in a small but sturdy plastic ziplock bag, which is why the photo looks a little odd.
My friend Steve Rosenthal sent two of the exact same kind of pink-rayed tellins from Long Island to Harry G. Lee, and Harry looked at the pallial line inside the shells, and confirmed that they were definitely Angulus versicolor.
New to the Database!
And also new to Wards Island.
Possibly new to Manhattan?
Might even be a new record for NYC?
Fotos / Sonidos
Qué
Macoma petalumObserv.
susanhewittDescripción
Two are paired valves, and two, including the largest one, are single valves.
Comentarios
Probably very few shell hunters on the Harlem River. Lots of time for accumulation.
That sounds logical Sarka, and that probably helps in some ways, but in general, beach drift does not get a chance to accumulate there.
That's because the Harlem River is fairly narrow, and the beach is quite small and fairly flat. Every time a boat such as the ferry boats and the Circle Line boats go by, the waves created by the boat's wake run all the way up the little beach to the sea wall and back down again, washing almost every shell back into the water again! Many of the shells are thin and fragile, and they do not last long when they are washed around roughly like that.
Yesterday there were seven neighborhood children from East Harlem on this little beach, and they were playing in the water, and also collecting some shells. :) Maybe when it gets to be full summer more children will visit there.
I would be interested in digging a few holes, see that's in there and also test the soil for contaminants. Also the water. That would be interesting & fun :)
Those sound like great ideas!
There was a fish count supposedly going on yesterday on the island. I will try to see if I can get the results. Maybe they tested the water?
I did ask, and should be getting their results soon.
@sarka -- I wish you were close enough to do that, then also I could learn from you.
Are you ever visiting, or transiting through, New York?
ThAt would be nice. No, I don't go that way anymore. However, when you are down in the Caribbean next time, I'll go out of my way! Always looking for somewhere new to go. BTW, I bumped into your publications in reseachgate a while back.
OK!
Ed and I will almost certainly be on Nevis next year again as usual for 4 weeks in April or May. But Nevis is a little expensive to get to.
I have to get a lot more of my publications up on ResearchGate -- I Just never seem to get around to doing that.
The salinity was tested there during the Annual Fish Count last week, and it was 20.5 ppt.
That is definitely brackish.
I am amazed that all these species can tolerate brackish water. I did not know that.
Don't take that number as gospel. Sometimes the refractometers get out of calibration. It may not have been reading correctly. If you send me a water sample I can double check it for you.
That's very kind of you Sarka. The water is very murky though -- is that a problem?
No, not at all.
Martinez, POB 155, Orcas, WA 98289
And how much do you need? and what is the best way to send it?
5 tablespoons will be more than enough. It doesn't need to get here fast.
Let me first see if I can get the RIPA staff to test it again for me.
Yesterday the Natural Areas staff told me the ranges of Salinity that they get when they test it. It is often around 20. Apparently it ranges from 30 down to 12.
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