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There is increasing evidence for accelerated deep-water formation at the end of glacial periods (Knorr & Lohmann, 2003). During deglaciation, the Atlantic thermohaline circulation becomes more vigorous. It changes from a weak glacial mode into a strong interglacial mode, triggered either by 1) southern warming and increased northwards transport of denser, salty waters from the tropics into the “sinking regions” at high latitudes, where they ultimately initiate thermohaline circulation, or 2) by injection of fresh water from the Antarctic ice-sheet. In consequence, the density of deep and intermediate waters from Antarctica, which compete in the Atlantic with North Atlantic Deep Water (NADW), is reduced, eventually accelerating the termohaline circulation (Knorr & Lohmann, 2003). There is also recent evidence that there may be a variety of sites of deep-water formation in the N. Atlantic (Pickart et al., 2003). If this more vigorous formation of deep water occurs at transitional periods similar to the end of glacial periods it may be that the warming of surface waters stimulates accelerated reproduction, both through temperature and primary production and that the resultant larvae using the thermohaline ‘conveyer belt’, are able to penetrate the deep sea. Tyler et al. (1995) hypothesized on the basis of biogeographic distributions in the genus Echinus, that the western boundary undercurrent, which transports North Atlantic Deep Water (NADW), formed in the Norwegian Sea, south along the slope of the eastern margin of North America, was capable of transporting larvae from the centre of speciation in the North Atlantic to the South Atlantic and Pacific Oceans. Reduced flow of NADW during glacial periods has probably resulted in allopatric speciation of isolated populations of Echinus at these sites (Young et al., 1997). Experimental work on the pressure and temperature tolerances of embryos and 23
larvae of shallow water echinoids from the northern Mediterranean (Young et al., 1997b) show that larvae are sufficiently tolerant of high pressures to follow an isothermal layer of warm water into the deep Mediterranean Sea. Embryos and larvae of the shallow water echinoids Paracentrotus lividus Lamarck, Arbacia lixula , and Sphaerechinus granularis tolerated pressures as high as 150 atm at 15°C. Lower temperatures (
Page 1 and 2: University of Southampton Research
Page 3 and 4: Graduate School of the National Oce
Page 5 and 6: UNIVERSITY OF SOUTHAMPTON ABSTRACT
Page 7 and 8: Marthasterias glacialis (ECHINODERM
Page 9 and 10: Acknowledgments I know everybody sa
Page 11 and 12: Prière de l’étoile de mer Seign
Page 13 and 14: species of asteroid Patiriella para
Page 15 and 16: embryonic tolerances could determin
Page 17 and 18: dispersed over great distances and
Page 19 and 20: lecithotrophic development. The pre
Page 21 and 22: al., 1997). In a review (Vrijenhoek
Page 23: Although larval dispersal and settl
Page 27 and 28: few hours, whereas other species su
Page 29 and 30: een defined as a unique sequence of
Page 31 and 32: therefore a developing form may wel
Page 33 and 34: adults” that have the definitive
Page 35 and 36: The dipleurula is the hypothetical
Page 37 and 38: among tunicate tadpoles, sponge and
Page 39 and 40: Fig.2.4. Bipinnaria larvae of the a
Page 41 and 42: In marine invertebrates there is a
Page 43 and 44: independent of habitat or mode of n
Page 45 and 46: whether juveniles derived from larv
Page 47 and 48: and the northern Mediterranean have
Page 49 and 50: Wares (2001) performed phylogenetic
Page 51 and 52: Fig. 3.2. A. Marthasterias glaciali
Page 53 and 54: 3.2.2- Temperature/pressure effects
Page 55 and 56: Pressure was applied using an Enerp
Page 57 and 58: Fig. 3.7. Bippinaria larvae of Mart
Page 59 and 60: X Data were abnormal. At 150 and 20
Page 61 and 62: X Data all the embryos were abnorma
Page 63 and 64: X Data blastulae, at 200atm 90% of
Page 65 and 66: 50atm more than 90% of embryos were
Page 67 and 68: Those data (Young et al., 1997; Ped
Page 69 and 70: Percentage of individuals swimming
Page 71 and 72: that settling invertebrate larvae d
Page 73 and 74: CHAPTER FOUR- REPRODUCTIVE FEATURES
Page 75 and 76:
In 1973, Vance proposed a theoretic
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Species Volume Energy Dev Class Ref
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4.1.2- Body Size The reproductive o
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Species Depth of max. Depth range (
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arm, and the minor radius (r), from
Page 86 and 87:
From Eqs.1 and 3 we obtain the esti
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Data on maximum body size, maximum
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250 200 Body size (mm) 150 100 50 0
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Fig. 4.7. Hierarchical cluster anal
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(Hymenaster membranaceus Thomson).
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gamete production at low population
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varies depending on the vitellogeni
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size, high fecundity, small egg siz
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strategy described by Winemiller an
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It seems that evolutionary features
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strategy stablished by the Winemill
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which normal embryonic/larval devel
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Larval dispersal from eight populat
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These results are very important si
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possibility. The opportunistic spec
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hypothesis that the Mesozoic and ea
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Barnes, H. and H.T. Powell. 1951. T
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Chester, C.M. 1996. The effect of a
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Crisp, D.J. 1978. Genetic consequen
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David, B., A. Guille, J-P. Féral a
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Grant, A. 1983. On the evolution of
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Inaba, D. 1934. On some holothurian
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of the 6 th International Echinoder
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Lieberkind, I. 1926. Ctenodiscus au
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McEdward, L.R. and S.F. Carson. 198
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Minchin, D. 1987. Sea-water tempera
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Pawson, D.L. 1976. Some aspects of
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Pingree. R.D., B. Sinha and C.R. Gr
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Savidge, G., H.J. Lennon, and A.D.
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Shilling, F.M. and D.T. Manahan. 19
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Turner, R.L. and J.M. Lawrence. 197
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Vickery, M.S. and J.B. McClintock 2
Page 150 and 151:
(Eds.): Reproduction Genetics and D
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