J. Caceresmartinez et al., SETTLEMENT AND POST-LARVAE BEHAVIOR OF MYTILUS-GALLOPROVINCIALIS - FIELD AND LABORATORY EXPERIMENTS, Marine ecology. Progress series, 112(1-2), 1994, pp. 107-117
Field sampling carried out in the Ria de Vigo (NW Spain) from 1991 to
1993 showed that Mytilus galloprovincialis settle directly from the pl
ankton onto substrates exposed to various environmental conditions: ex
posed rocky shore; protected rocky shore; exposed, raft mussel-culture
area; and protected, raft mussel-culture area. For direct settlement,
competent larvae may use a wide variety of substrates: filamentous ny
lon ropes; the byssus and intricately arranged material in the bottom
of mussel beds; filamentous, thallus and membranous algae; and rugosit
ies on adult mussel shells. The peak of settlement occurred from sprin
g to early autumn and differences in the settlement abundance among lo
calities were influenced by currents. After this peak, the settlement
of larger post-larvae continued, associated with the increase in storm
s during autumn that detach them from their original substrates. This
dispersion phase allows for the possibility of colonising, or recruiti
ng on other areas, even during the post-spawning season when the prese
nce of small post-larvae is at its minimum. Laboratory experiments car
ried out with post-larval stages from 0.250 to 2.000 mm showed that un
der static water conditions they crawl and form clumps, but do not sea
rch for a specific substrate. If they are not disturbed, they may rema
in in their original place of settlement. Conversely, under moving wat
er conditions they attach to a wide variety of substrates, particularl
y to byssal filaments and thalli of red algae Ceramium rubrum. The con
tact and attachment to substrates is carried out with a long mucous th
read that also aids in forming clumps. The use of this mucus to settle
results in a 'preference' for natural filamentous substrates but also
in settlement on rugous hard surfaces. An alternative hypothesis to t
he primary and secondary settlement pattern previously described in th
e literature for Mytilus edulis is suggested.