Advances in Marine Biology (eBook)

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2007 | 1. Auflage
392 Seiten
Elsevier Science (Verlag)
978-0-08-047118-1 (ISBN)

Infos

Advances in Marine Biology was first published in 1963. Now edited by David W. Sims (Marine Biological Association, UK), the serial publishes in-depth and up-to-date reviews on a wide range of topics which will appeal to postgraduates and researchers in marine biology, fisheries science, ecology, zoology, oceanography. Eclectic volumes in the series are supplemented by thematic volumes on such topics as The Biology of Calanoid Copepods and Restocking and Stock Enhancement of Marine Invertebrate Fisheries.

* More than 350 pages of reviews from leading researchers in marine biology
* Includes over 90 images
* Offers reviews on the biology of the glass sponge
* Reviews protein metabolism in marine animals

Inhalt

Front Cover 1
Advances in Marine Biology 4
Copyright Page 5
Contributors To Volume 52 6
Contents 8
Series Contents for Last Ten Years 10
Chapter 1: The Biology of Glass Sponges 15
1. Introduction 17
2. General Organisation 19
2.1. Gross morphology 19
2.2. Structure of the body wall 19
3. Cells and Syncytia 23
3.1. Definitions 23
3.2. Plugged junctions 24
3.3. Hexactinellid plugs compared with other junctions 27
3.4. Trabecular syncytium 29
3.5. Sclerocytes and sclerosyncytium 31
3.6. Archaeocytes 32
3.7. Cells with inclusions 32
3.8. Choanocytes 34
3.9. Mesohyl 38
4. Tissue Dynamics 38
4.1. Reaggregation of dissociated sponge tissue 38
4.2. Fusion 41
4.3. Cytoskeleton 43
4.4. Organelle transport 47
4.5. Comparison with cellular sponges 51
4.6. Immune response 52
5. Physiology 53
5.1. Hexactinellids as experimental animals 53
5.2. Food and wastes 54
5.3. Production and control of feeding currents 64
6. The Siliceous Skeleton 73
6.1. Discrete spicules 73
6.2. Megascleres and microscleres 74
6.3. Spicule locations 80
6.4. Fused silica networks 82
6.5. Silication 90
7. Ecology 99
7.1. Habitats: distribution and abundance 99
7.2. Succession: glass sponge skeletons as substrates 101
7.3. Reefs or bioherms 104
7.4. Growth rates and seasonal regression 108
7.5. Predation, mortality and regeneration 110
7.6. Recruitment 113
7.7. Symbioses: animal-plant associations 115
8. Reproduction 118
8.1. Sexual reproduction 118
8.2. Asexual reproduction 130
9. Classification and Phylogeny 130
9.1. Classification of recent Hexactinellida 130
9.2. Classification of fossil Hexactinellida 133
9.3. Phylogeny of Hexactinellida within Porifera 139
9.4. Phylogeny within Hexactinellida 142
10. Conclusions 145
Acknowledgements 146
References 146
Chapter 2: The Northern Shrimp (Pandalus borealis) Offshore Fishery in the Northeast Atlantic 161
1. Introduction 163
2. The Ecology of Pandalus borealis within the Study Area 165
2.1. Geographical distribution 165
2.2. Environmental requirements 167
2.3. Biology 169
2.4. Population structure 174
2.5. Predators and parasites 174
3. Iceland 174
3.1. The fishery 174
3.2. Management 182
3.3. Research 185
3.4. Bycatch in the Icelandic shrimp fishery 188
4. Greenland 197
4.1. The fishery 197
4.2. Management 206
4.3. Research 213
4.4. Bycatch in the Greenland shrimp fishery 221
5. Svalbard, the Barents Sea and Jan Mayen 228
5.1. The fishery 228
5.2. Management 232
5.3. Research 235
5.4. Bycatch in the Svalbard shrimp fishery 241
6. Overview 244
Acknowledgements 254
References 254
Chapter 3: Protein Metabolism in Marine Animals: The Underlying Mechanism of Growth 281
1. Introduction 283
1.1. Overview 283
1.2. The processes of protein synthesis, degradation and growth 286
2. Protein Metabolism Methodologies 288
2.1. Overview 288
2.2. Constant infusion 288
2.3. Flooding-dose 289
2.4. Stochastic endpoint models 294
2.5. Protein degradation determinations 297
2.6. Transcriptomics 299
3. Whole-Animal Protein Metabolism 301
3.1. Overview 301
3.2. Abiotic factors influencing protein metabolism 304
3.3. Biotic factors influencing protein metabolism 311
4. Tissue and Organ Protein Metabolism 316
4.1. Overview 316
4.2. Abiotic factors influencing protein metabolism 316
4.3. Biotic factors influencing protein metabolism 328
5. In Vitro and Cell-Free Protein Metabolism 334
5.1. Overview 334
5.2. Abiotic factors influencing protein metabolism 334
5.3. Biotic factors influencing protein metabolism 336
6. Larval Protein Metabolism 337
6.1. Fish 337
6.2. Invertebrates 340
7. Energetic Costs of Protein Synthesis 341
8. Protein Synthesis and RNA 345
9. Summary and Future Research Directions 354
9.1. Protein metabolism of marine organisms 354
9.2. Protein metabolism of polar marine organisms 356
9.3. The future 357
Acknowledgements 358
References 359
Taxonomic Index 377
Subject Index 381

Textauszug

8 Reproduction

8.1 Sexual reproduction

8.1.1 Reproductive periods

Reproductive periods for hexactinellids vary depending on the species and possibly even the population. Records are scant and most stem from early collection expeditions in which scientists were focusing specifically on morphology and thus carried fixatives to preserve tissues and larvae (Schulze, 1880, 1887, 1899; Ijima, 1901, 1904; Okada, 1928). There are three recent studies (Boury‐Esnault and Vacelet, 1994; Leys and Lauzon, 1998; Leys et al., 2006).

Ijima (1901) made a special search at different seasons for reproductive cells in Euplectella marshalli but found neither developmental stages nor larvae. In subsequent collections of rossellid hexactinellids (Ijima, 1904), he still only found developmental stages and larvae in very few specimens. In Vitrollula fertilis, he found larvae in April, larvae and various developmental stages in July but only archaeocyte congeries in November, and from this presumed that the main active reproductive period is in early summer.

Okada (1928) probably carried out the most extensive survey of reproduction in a single population by collecting specimens of F. sollasii (Farreidae, Hexactinosida) monthly from the Nakanoyodomi (about 600 m deep) in the Sagami Sea. After Ijima's work, he was surprised to find reproductive specimens every month, and suggested that the breeding season was likely year‐long because of the fairly constant temperature and uniform environmental conditions that exist at that depth. Other surveys have not had the same luck as Okada, however. Although deep sea expeditions do occasionally report finding a reproductive glass sponge, a survey of tissue collected monthly from the NE Pacific rossellid species Rhabdocalyptus dawsoni failed to turn up anything but archaeocyte congeries (Leys and Lauzon, 1998). However, a study of samples of Heterochone calyx collected in October 1982 by one of us (H.M.R.) has revealed one specimen with numerous spermatocysts (accounting for approximately half of the congeries), some of which appeared to have emptied their contents, thus possibly having spawned, and many early embryos in various stages of cleavage. Of the many specimens of the NE Pacific reef‐building sponge Aphrocallistes vastus that have been collected since the early 1980s, developing embryos were only found in one specimen collected in November 1995. Despite extensive work on glass sponges in Antarctic waters, there are no reports of sexually reproductive individuals. Thus, it is likely that shallower populations (those in the NE Pacific and Antarctica) are affected by seasonality of the surface waters more than deep‐water populations. The hint from the two Heterochone and Aphrocallistes individuals is that reproductive period occurs in the autumn.

8.1.2 Gametogenesis

The bulk of our knowledge on reproduction in glass sponges stems from studies on two animals: F. sollasii (Okada, 1928) and Oopsacas minuta (Boury‐Esnault and Vacelet, 1994; Boury‐Esnault et al., 1999; Leys et al., 2006). This section of development will draw heavily from these accounts and from that information provided in Ijima's description (1904) of larvae in V. fertilis. The genera used below refer to the species used in these studies.

Gametes—both sperm and eggs—arise within archaeocyte congeries that are suspended within the trabecular reticulum between flagellated chambers (Okada, 1928; Boury‐Esnault et al., 1999). Spermatocysts are first identifiable as dense groupings of archaeocytes up to 30 μm by 23 μm in Oopsacas minuta surrounded by a thin (0.5 μm) layer of the trabecular reticulum (Figure 50A and B). In young spermatocysts, cells are larger in the centre than at the periphery of the cyst, ranging from 2.7 to 5.3 μm in diameter with a nucleus 1.6–2.6 μm and a nucleolus 0.5–1 μm (Boury‐Esnault et al., 1999). Each cell has a flagellum that coils around the cell. All spermatocytes cells are connected by plugged cytoplasmic bridges, and cells at the periphery of the cyst are connected to the surrounding trabecular envelope by plugged cytoplasmic bridges. At this point, the characteristics of free sperm remain unknown.

Figure 50 Gametogenesis. (A) Scanning electron micrograph of a spermatocyst in the adult tissue of Oopsacas minuta. (B) Higher magnification of two spermatids connected by a cytoplasmic bridge (arrow) in the spermatocyst shown in A. The flagellum (fl) is coiled around each cell body. (C) Scanning electron micrograph of an oocyte fractured in half. (D) Higher magnification of the oocyte in C showing lipid‐dense inclusions occupy the periphery and the surface has numerous microvilli (Leys, unpublished images).

Oogenesis also occurs within archaeocyte congeries. The first oocyte is identifiable as a large cell (10 μm in diameter) within the congerie that has begun to accumulate yolk and lipid inclusions (Okada, 1928; Boury‐Esnault et al., 1999) (Figure 50C and D). Archaeocytes are connected to one‐another by plugged cytoplasmic bridges and are suggested to act as nurse cells providing the lipid and yolk to the developing oocyte. But at some point the oocyte presumably breaks this connection because the mature oocyte is a completely independent ovoid cell 100–120 μm in diameter in Oopsacas minuta (Boury‐Esnault et al., 1999) and 70–130 μm in F. sollasii (Okada, 1928), with large lipid inclusions (3.2‐ to 6.7‐μm diameter) at the periphery and membrane‐bound yolk inclusions (1.3–2.7 μm) and very small vacuoles more centrally. Boury‐Esnault et al. (1999) describe a 45 to 50 μm diameter nucleus with a 10 μm nucleolus within the oocyte, but although a subsequent study (Leys et al., 2006) found identifiable nuclear regions at the light microscope level, a nuclear membrane was not visible in any thin section studied by transmission electron microscopy. This may be what Okada referred to as a ‘vesicular’ nucleus (Okada, 1928, p. 3). The presumed nuclear material forms a dense osmiophilic region that occupies the centre of the cell and radiates out into the peripheral regions of the cytoplasm, not unlike the chromatin in the nucleoids of some bacteria (Robinow and Kellenberger, 1994). The surface of the oocyte has numerous short pseudopodia. Okada found most oocytes at the outer trabecular layer of F. sollasii and suggested that after fertilisation they migrate in to the inner trabecular layer to lie beside a flagellated chamber. In Oopsacas minuta, however, oocytes and developing embryos can be found throughout the body wall, from just under the dermal membrane to just under the atrial membrane, where they lie adjacent to flagellated chambers.

8.1.3 Embryogenesis

Cleavage is total and equal, but asynchronous, for the first five cycles until the embryo has approximately 32 cells (Figures 51 and 54). The embryo remains of the same size during these divisions, partitioning cytoplasm, yolk and lipid into daughter blastomeres. Early blastomeres retain all the characteristics of the oocyte, with pseudopodia extending from their surface, a dense nuclear region, large lipid inclusions at the periphery and membrane‐bound yolk inclusions more centrally. It is not until the 32‐cell stage (blastula) that a distinct nucleus can be seen in individual blastomeres (Leys et al., 2006). This feature may reflect the fact that divisions are rapid, leaving little time for re‐assembly of the nuclear membrane between cycles. If so, the appearance of nuclei at this stage—concurrent with the change to unequal cleavage—could reflect slowing of the cell cycle.

Figure 51 Embryogenesis. Stages in development of Oopsacas minuta as seen by light microscopy (A, B, D, E), scanning (C), and transmission electron microscopy (F) and as drawn by Okada (1928) (G, H) (A–F, Leys, unpublished data). (A, B) Two‐ and four‐cell embryo. (C, D) Thirty‐two cell blastula. (E) Macromeres fuse to form increasingly larger cells and eventually a single syncytial tissue, the trabecular tissue. (F) Macromeres envelop micromeres (arrowheads), which are connected to one‐another by plugged cytoplasmic bridges (arrow). (G) Okada's drawing of an embryo from Farrea sollasii at approximately the same stage as E (Plate 5, Figure 7). (H) Okada's drawing of cells at the periphery of the embryo in G. Cells are enveloped by a reticulate tissue (arrowhead by S.P.L.).

Figure 54 Stages in embryogenesis and larval development of Oopsacas minuta (after Leys et al., 2006). (A) Oocyte, (B) two cells, (C) four cells, rotational or equatorial cleavage, (D) eight cells, (E) hollow blastula, (F) unequal cleavage to form micromeres (mi) and macromeres (ma), (G) gastrulation: fusion of macromeres (ma) to form the trabecular syncytium, and envelopment of micromeres...

Produkt-Details

• Erscheint lt. Verlag: 22.2.2007
• Mitarbeit: Herausgeber (Serie): D.W. Sims
• Sprache: englisch
• Themenwelt: Sachbuch/Ratgeber
• Themenwelt: Naturwissenschaften ► Biologie ► Limnologie / Meeresbiologie
• Themenwelt: Naturwissenschaften ► Biologie ► Ökologie / Naturschutz
• Themenwelt: Naturwissenschaften ► Biologie ► Zoologie
• Themenwelt: Technik ► Umwelttechnik / Biotechnologie
• Themenwelt: Wirtschaft
• Themenwelt: Weitere Fachgebiete ► Land- / Forstwirtschaft / Fischerei
• ISBN-10: 0-08-047118-8 / 0080471188
• ISBN-13: 978-0-08-047118-1 / 9780080471181