Biology Reference
In-Depth Information
STREETCAR REEFS
In the 1960s, sportfishermen and fisheries biologists became interested
in establishing artificial reefs in flat, featureless sandy or muddy bottom
areas. This was perceived as a way to increase available reef habitat that
would then attract resident fish for the benefit of fishermen and divers.
In line with this philosophy, a number of old Los Angeles streetcars
were dumped over a sandy area near the south end of Santa Monica
Bay. A few months after they were installed I had a chance to dive on
them with Earl Ebert and Chuck Turner, biologists with the Califor-
nia Department of Fish and Game. The underwater reefs had already
attracted a healthy population of fish, and it was quite humorous to
watch them swimming in and out through the windows or perched
on the streetcar seats.
The streetcar reef was one of those projects that initially seemed like
a good idea but in reality was not. Having seen the e¤ect of marine
animals on the untreated parts of wooden pier pilings, I knew these
wooden streetcars would soon be devoured by the prolific underwater
teredos, or shipworms—which, despite the name, are not worms at all
but are wood-eating clams ( Te r edo and Bankia spp.) with long siphons—
and by crustaceans known as gribbles ( Limnoria spp.). All that would
remain would be the rusting metal and the glass windows.
The streetcar reef did o¤er us at least one thrill. Over a nearby area
of sandy bottom about a city block in size we came across hundreds
of giant sheep crabs. In some places they were literally piled on top of
one another. Both sexes were present, with the larger males having a
leg spread of over two and a half feet.
It was the first and only time I have seen such an aggregation. Where
did they come from, and why did they come to this particular place?
Sheep crabs move rather slowly, and if they came from far away, which
I assume they did, it must have taken them quite some time to get to
where they were now. How did they know where they were going, and
what was it that prompted this massive migration? Perhaps it was for
reproduction. I had occasionally seen mating sheep crabs at other places,
but it was always just a single pair, not a huge gathering like this. It
still puzzles me.
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