000			03934nam a2200337 i 4500
001			000284723
003			UVAL
005			20240507121740.0
006			a|||||r|||| 00| 0
007			ta
008			221006s1988 vau||||| m||| 00| 0 eng d
040			_aDIBRA _bspa _cUVAL _erda
041	0		_aeng
084			_aT
100	1		_aCampos Maia, Bernardita, _eautora _9105098.
245	1	0	_aSwimming responses of larvae of three mactrid bivalves to different salinity gradients / _cBernardita Campos Maia.
264		1	_aWilliamsburg, Virginia : _bCollege of William and Mary, _c1988.
300			_aviii, 115 hojas : _bilustraciones, fotografías.
336			_atext _btxt _2rdacontent
337			_aunmediated _bn _2rdamedia
338			_2rdacarrier _avolume _bnc
500			_aIncluye anexos.
502			_bMaster of Arts. _cCollege of William and Mary. _cSchool of Marine Science. _d1988.
504			_aBibliografía: hojas 95 - 109.
520			_aLarval swimming behavior in response to varied salinity conditions is an important component of active mesoscale dispersal mechanisms. Vertical distribution in salinity gradients of 0,5, 10 and 15°/oo in magnitude was examined for straight-hinge, umbo and pediveliger larvae of the mactrid bivalves Spisula solidissima, Mulinia lateralis and Rangia cuneata. Vertical swimming and sinking velocities were measured at constant temperature and light, and variable salinity depending on the species. Laboratory cultured larvae were used for the experiments. Larvae concentrated in the discontinuity independently of the species, stage of development and larval brood. Spisula solidissima larvae initially swimming in a 30°/ oo salinity layer crossed a discontinuity of 5° / oo and 10°/ oo discontinuity magnitude but nota 15°/ oo salinity discontinuity. Mulinia lateralis larvae initially swimming in the 25°/ oo salinity layer also crossed a discontinuity of 5°/ oo salinity magnitude but they did not swim through a discontinuity of 10 and 15°/ oo salinity magnitude. Rangia cuneata larvae initially swimming in a 10°/ oo salinity layer crossed even a discontinuity of 15°/ oo sallinity magnitude but they mostly concentrated in the 10°/ oo salinity layer and in the discontinuity. Vertical velocity changed with larval stage with the peak in the umbo stage, independently of the species . Upward vertical velocity in S. solidissima larvae ranged from 0.18 to 0.49 mm s-1 and increased with an increase of salinity. Upward vertical velocity in M. lateralis larvae ranged from 0.25 to 0.50 mm s -1 but no consistent pattern in relation to salinity was observed. Upward vertical velocity in R. cuneata larvae ranged from 0.18 to 0.53 mm s -1 . The lowest velocity was measured in the highest salinity, but in pediveliger larvae, the opposite was observed. Downward vertical velocities were similar to the upward velocities values . No significant differences in downward vertical velocity were detected in relation to salinity. Passive sinking was more frequent than active downward swimming in umbo and pediveliger larvae. Sinking velocity increased with larval size in S. solidissima and M. lateralis larvae; however, R. cuneata straight-hinge larvae sank faster than umbo and pediveliger larvae. The velar morphology was different in the three species. Although the outer ciliary band had short blunted tips irrespective of the species, the inner ciliary band and the central ciliary tuft bore long cilia with paddles in S. solidissima, discs in M. lateralis but regular blunted cilia in R. cuneata . The implications of the observed larval behavior and morphological characteristics of the velum on larval depth regulation and dispersal are discussed.
650	1	4	_aBIVALVOS _933534.
650	1	4	_aLARVAS DE MOLUSCOS _933692.
700	1		_aMann, Roger, _eProfesor guía _9237679.
710	2		_aCollege of William and Mary. _bSchool of Marine Science _9237681.
942			_2ddc _c5
999			_c284723 _d284723