K.N.I. Bell: Tropical Anadromous Gobies -- Sicydium & others
Bell main site page --- --- main goby page --- How it started -- Intro -- Larvae
I have been keen on gobies for a very long time. My work interests me for its own sake, but I always try, whenever there's a choice, to follow (a) what might be useful for conservation, and (b) what others haven't noticed or what seemed too risky.
A brilliant blue-phase (territorial colouring) male Sicydium punctatum from Dominica, West Indies, perched on a rock.
This (above) was undoubtedly the
first witnessed nest of a sicydiine goby from the Caribbean (before,
only one instance of unfertilised eggs was seen, deposited
by
a
lone
female
on
the
wall
of
a
concrete water tank in Puerto Rico, reported by Donald S. Erdman). For
scale,
the
filter
slats
are
about
7mm. This is the male guarding the nest. |
Einar Wide and I collecting gobies just above the Hillsborough
bridge on Layou River, long ago. Multi-use of rivers continues to
this day. Some years later I sampled plankton
a little way above here, and below. |
Life cycle. Adults live in rivers. Eggs laid on the roof of little caves that the male digs out under rocks. Larvae hatch and then commence swimming up, sinking down, swimming up, drifting down, etc., and all the while they are carried by the stream to the sea. Larvae grow in the sea for a few months (varies worldwide, and varies across species; we aren't sure why; but in Dominica the range seen for Sicydium punctatum is 50 to about 150 days). Then they return to fresh waters (recruitment). | Note the diagram marks "Fishery". "Tri-tri" is the local name for the postlarvae, and they are so different from the adults that virtually everybody would ask me "Oh, you're working on tri-tri; tell me, where do they come from?" Or, some wanted to tell their theory; those ranged from a big mass of foam in the ocean, to a big mama tritri in the river (the closest but it was still not connected with the Loche, the local name for the adult Sicydium), to origins in a big bag, like a plastic bag. The latter seemed the wackiest, but after one very smart lady said the same I realised it might refer to postlarvae seen inside jellyfish (but that again is a theory, the story might mean something different again). I call these taxa (the gobies, shrimps and gastropods) anadromous. Some use the word amphidromous; the differences are subtle and all classifications that are not mutually exclusive are descriptors, not categories. But few enough know what 'anadromous' is; I see no point in using a word that fails to communicate with the intended reader. The effective meaning of "amphidromous" to those working on these groups, is "this group", so it communicates little to them*; few others workers know it, so, ironically, ditto. (*like writing in J. Ferrous Metals "iron, a ferrous metal"). |