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possibility. The opportunistic species are distinctive of highly disturbed and unpredictable environments (Winemiller and Rose, 1992; McCann and Shuter, 1997). The zone between 1100 and 3000 m coincides with the transitional zone proposed by Howell et al. (2002) where boundaries at 2500, 2800 and 3300 m are thought to demonstrate a region of transition between bathyal and abyssal fauna. Evolutionarily, bathyal species are likely to have a mixed origin, with some species from the shelf and some originating from abyssal depths (Rogers, 2000). Six of the nine species found below 3000 m in this study belong to the Porcellanasteridae, a family found entirely in the deep sea. It is likely that the reproductive features at this zone are also related to historical factors affecting evolutionary pathways. (Vinogradova et al., 1959). Rice et al. (1991) found that the base of the continental slope in the NE Atlantic occurs at ~ 3300 m and Howell et al. (2002) proposed that this may represent a barrier to abyssal species. The abyssal zone is inhabited by asteroids with reproductive features of equilibrium K strategists (Winemiller and Rose, 1992), which have low fecundity, large egg size and expected high juvenile survivorship, although their large body size makes them more comparable to the classical K strategists (MacArthur and Wilson, 1967; Pianka, 1970). K strategists are characteristic inhabitants of constant environments (Winemiller and Rose, 1992; McCann and Shuter, 1997). 5.5- Final remarks From the earliest days of deep-sea exploration, it was assumed that animals living in the presumably invariable environments of the deep sea should show lifehistory features and reproductive modes differing from those of their shallow water congeners, but the most recent investigations show that with few exceptions, the 101
eproductive mechanisms and patterns found in deep-water echinoderms like other taxonomic groups are similar to those found in shallow-water species (Young. 2003). It was also supposed that the rate at which biological processes occur is slower in the deep sea than in shallow waters, but some rates in the deep sea may be similar to or only slightly lower than rates in shallow waters (Gage, 1991; Thistle, 2003). Recent discoveries and long-term, time-series investigations have made clear that the deep sea, and in particular the deep Atlantic, is a dynamic ocean whose inhabitants undergo environmental variation over an extensive range of spatial and temporal scales. However, the vertical gradients of environmental stability and availability of nutrients that sustained the earliest predictions for the deep sea, still provide a useful framework for considering how natural selection has given form to the life-history attributes of deep-sea animals (Young, 2003). Today we recognize that the deep ocean is not an isolated system, but interacts with global surface circulation and ocean atmosphere interactions, therefore the high levels of variability exerted by global climate change and disturbances produced by anthropogenic activity on oceanic zones have also an increasing effect on deep waters affecting the biological processes of deep-sea communities. It is important to remark that in the present study the results showed that temperature is a determinant environmental factor that might allow or prevent the shallow-water species of colonizing the deep sea. The experiments performed with embryos and larvae of Asterias rubens and Marthasterias glacialis provided evidence that the embryos and larvae have a elevated tolerance to high pressures when the temperature is appropriate. Young et al. (1997) also found that larvae of shallow water Mediterranean echinoids tolerate relative high pressures at temperatures that prevail in the modern Mediterranean Sea, those findings give impetus to the 102
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University of Southampton Research
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Graduate School of the National Oce
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UNIVERSITY OF SOUTHAMPTON ABSTRACT
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Marthasterias glacialis (ECHINODERM
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Acknowledgments I know everybody sa
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Prière de l’étoile de mer Seign
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species of asteroid Patiriella para
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embryonic tolerances could determin
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dispersed over great distances and
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lecithotrophic development. The pre
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al., 1997). In a review (Vrijenhoek
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Although larval dispersal and settl
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larvae of shallow water echinoids f
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few hours, whereas other species su
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een defined as a unique sequence of
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therefore a developing form may wel
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adults” that have the definitive
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The dipleurula is the hypothetical
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among tunicate tadpoles, sponge and
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Fig.2.4. Bipinnaria larvae of the a
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In marine invertebrates there is a
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independent of habitat or mode of n
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whether juveniles derived from larv
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and the northern Mediterranean have
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Wares (2001) performed phylogenetic
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Fig. 3.2. A. Marthasterias glaciali
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3.2.2- Temperature/pressure effects
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Pressure was applied using an Enerp
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Fig. 3.7. Bippinaria larvae of Mart
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X Data were abnormal. At 150 and 20
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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
Page 77 and 78: Species Volume Energy Dev Class Ref
Page 79 and 80: 4.1.2- Body Size The reproductive o
Page 81: Species Depth of max. Depth range (
Page 84 and 85: arm, and the minor radius (r), from
Page 86 and 87: From Eqs.1 and 3 we obtain the esti
Page 88 and 89: Data on maximum body size, maximum
Page 90 and 91: 250 200 Body size (mm) 150 100 50 0
Page 92 and 93: Fig. 4.7. Hierarchical cluster anal
Page 94 and 95: (Hymenaster membranaceus Thomson).
Page 96 and 97: gamete production at low population
Page 98 and 99: varies depending on the vitellogeni
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Page 104 and 105: It seems that evolutionary features
Page 106 and 107: strategy stablished by the Winemill
Page 108 and 109: which normal embryonic/larval devel
Page 110 and 111: Larval dispersal from eight populat
Page 112 and 113: These results are very important si
Page 116 and 117: hypothesis that the Mesozoic and ea
Page 118 and 119: Barnes, H. and H.T. Powell. 1951. T
Page 120 and 121: Chester, C.M. 1996. The effect of a
Page 122 and 123: Crisp, D.J. 1978. Genetic consequen
Page 124 and 125: David, B., A. Guille, J-P. Féral a
Page 126 and 127: Grant, A. 1983. On the evolution of
Page 128 and 129: Inaba, D. 1934. On some holothurian
Page 130 and 131: of the 6 th International Echinoder
Page 132 and 133: Lieberkind, I. 1926. Ctenodiscus au
Page 134 and 135: McEdward, L.R. and S.F. Carson. 198
Page 136 and 137: Minchin, D. 1987. Sea-water tempera
Page 138 and 139: Pawson, D.L. 1976. Some aspects of
Page 140 and 141: Pingree. R.D., B. Sinha and C.R. Gr
Page 142 and 143: Savidge, G., H.J. Lennon, and A.D.
Page 144 and 145: Shilling, F.M. and D.T. Manahan. 19
Page 146 and 147: Turner, R.L. and J.M. Lawrence. 197
Page 148 and 149: Vickery, M.S. and J.B. McClintock 2
Page 150 and 151: (Eds.): Reproduction Genetics and D
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