Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 1982. / Supervised by Peter Wiebe. Vita. Includes bibliographical references (leaves 322-337).

Graduation date: 1977

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982. / Vita. Includes bibliographical references (p. 321-337).

A study of the chaetognath population in the waters of western Canada was undertaken to discover what species were present and to determine their distribution. The plankton samples examined were collected by the Institute of Oceanography of the University of British Columbia in the summers of 1953 and 1954 from eleven representative areas along the entire coastline of western Canada. It was hoped that the distribution study would correlate with fundamental oceanographic data, and that the presence or absence of a given species of chaetognath might prove to be an indicator of oceanographic conditions. Four species of chaetognaths, representing two genera, were found to be present. One species, Sagitta elegans, was the most abundant and widely distributed species, occurring at least in small numbers in all the areas sampled. It was characteristic of the mixed coastal waters over the continental shelf and of the inland waters. Enkrohnia hamate, an oceanic form, occurred in most regions in small numbers as an immigrant, and was abundant toward the edge of the continental shelf. Sagitta lyra, strictly a deep sea species, was found only in the open waters along the outer coasts, and a few specimens of Sagitta decipiens, another oceanic form, were also taken in deep hauls from areas exposed to open ocean influence. It was found that the outer limit of Sagitta elegans corresponded with the inner limits of all three oceanic forms, though Eukrohnia hamata invaded the inland waters to some extent. / Science, Faculty of / Zoology, Department of / Graduate

Tésis (Biólogo marino)--Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, 1979. / Includes bibliographical references (leaves 57-62).

Thesis (M. Sc. (Zoology and Entomology))--Rhodes University, 2006.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 128-137.

Tse, Pan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 86-92). / Abstracts in English and Chinese. / Chapter Chapter 1. --- General introduction --- p.1 / Chapter 1.1. --- Chaetognatha --- p.1 / Chapter 1.2. --- Morphology and anatomy --- p.1 / Chapter 1.3. --- Food and feeding behaviour --- p.3 / Chapter 1.4. --- Locomotion --- p.3 / Chapter 1.5. --- Study location --- p.3 / Chapter 1.6. --- Significance of study --- p.4 / Chapter 1.61. --- Species composition and seasonal abundance --- p.4 / Chapter 1.62. --- Diel vertical migration and diel feeding activity --- p.5 / Chapter 1.63. --- Predation impact --- p.5 / Chapter 1.7. --- Objectives --- p.6 / Chapter Chapter 2. --- Species composition and seasonal abundance of Chaetognatha --- p.7 / Chapter 2.1. --- Introduction --- p.7 / Chapter 2.11. --- Species composition --- p.7 / Chapter 2.12. --- Study sites --- p.9 / Chapter 2.13. --- Objective --- p.9 / Chapter 2.2. --- Materials and methods --- p.11 / Chapter 2.21. --- Field sampling --- p.11 / Chapter 2.22. --- Laboratory analysis --- p.11 / Chapter 2.23. --- Data analysis --- p.12 / Chapter 2.3. --- Results --- p.12 / Chapter 2.31. --- Temperature and salinity --- p.12 / Chapter 2.32. --- Species composition --- p.14 / Chapter 2.33. --- Dominant species --- p.18 / Chapter 2.34. --- Species richness and species diversity --- p.20 / Chapter 2.4. --- Discussion --- p.23 / Chapter 2.41. --- Species composition --- p.23 / Chapter 2.42. --- Flaccisagitta enflata --- p.24 / Chapter 2.43. --- Aidanosagitta neglect a --- p.25 / Chapter 2.44. --- Aidanosagitta delicata --- p.26 / Chapter 2.45. --- Species richness and species diversity --- p.26 / Chapter 2.46. --- Prey abundance --- p.27 / Chapter 2.47. --- Spatial influences --- p.27 / Chapter 2.5. --- Conclusion --- p.28 / Chapter Chapter 3. --- Diel vertical migration and feeding activity of Flaccisagitta enflata --- p.29 / Chapter 3.1. --- Introduction --- p.29 / Chapter 3.11. --- Abundance --- p.29 / Chapter 3.12. --- Diel vertical migration --- p.29 / Chapter 3.12. --- Diel feeding activity --- p.30 / Chapter 3.13. --- Study sites --- p.30 / Chapter 3.2. --- Objectives --- p.31 / Chapter 3.3. --- Materials and methods --- p.31 / Chapter 3.31. --- Sample collection --- p.31 / Chapter 3.32. --- Laboratory analysis --- p.32 / Chapter 3.33. --- Data analysis --- p.32 / Chapter 3.4. --- Results --- p.33 / Chapter 3.41. --- Hydrography --- p.33 / Chapter 3.42. --- Flaccisagitta enflata abundance --- p.33 / Chapter 3.43. --- Diel vertical migration --- p.38 / Chapter 3.44. --- Dietary composition --- p.42 / Chapter 3.45. --- Prey abundance --- p.47 / Chapter 3.46. --- Food containing ratio --- p.51 / Chapter 3.5. --- Discussion --- p.51 / Chapter 3.51. --- Flaccisagitta enflata abundance --- p.51 / Chapter 3.52. --- Diel vertical migration --- p.55 / Chapter 3.53. --- Diel feeding activity --- p.57 / Chapter 3.6. --- Conclusion --- p.58 / Chapter Chapter 4. --- Predation impact of Flaccisagitta enflata on mesozooplankton --- p.59 / Chapter 4.1. --- Introduction --- p.59 / Chapter 4.11. --- Flaccisagitta enflata --- p.59 / Chapter 4.12. --- Prey --- p.59 / Chapter 4.13. --- Predation impact --- p.60 / Chapter 4.14. --- Feeding rate and digestion time --- p.60 / Chapter 4.2. --- Objective --- p.61 / Chapter 4.3. --- Materials and methods --- p.61 / Chapter 4.31. --- Sample collection --- p.61 / Chapter 4.32. --- Sample analysis --- p.61 / Chapter 4.33. --- Measurement of digestion time --- p.62 / Chapter 4.34. --- Data analysis --- p.62 / Chapter 4.4. --- Results --- p.64 / Chapter 4.41. --- Water temperature --- p.64 / Chapter 4.42. --- Flaccisagitta enflata distribution --- p.64 / Chapter 4.43. --- Prey distribution --- p.66 / Chapter 4.44. --- Food containing ratio --- p.66 / Chapter 4.45. --- Gut content --- p.66 / Chapter 4.46. --- Prey selectivity --- p.72 / Chapter 4.47. --- Predation impact --- p.72 / Chapter 4.5. --- Discussion --- p.77 / Chapter 4.51. --- Flaccisagitta enflata distribution --- p.77 / Chapter 4.52. --- Food containing ratio --- p.79 / Chapter 4.53. --- Gut content --- p.80 / Chapter 4.54. --- Cannibalism --- p.81 / Chapter 4.55. --- Prey selectivity --- p.82 / Chapter 4.56. --- Digestion time --- p.82 / Chapter 4.57. --- Predation impact --- p.83 / Chapter 4.6. --- Conclusion --- p.84 / Chapter Chapter 5. --- Conclusion --- p.85 / References --- p.86

No description available.

The community structure and predation impact of carnivorous macrozooplankton (>2 cm; chaetognaths, medusae, ctenophores and mysids), with particular emphasis on the chaetognaths Eukrohnia hamata and Sagitta gazellae, were investigated during three surveys conducted in late austral summer (April/May) of 2001, 2004 and 2005 in the Polar Frontal Zone in the vicinity of the Prince Edward Islands (46º45’S, 37º50’E), Southern Ocean. The 2001 survey formed part of the Marion Offshore Variability Ecosystem Study (MOVES II), while the 2004 and 2005 surveys formed part of the Dynamics of Eddy Impacts on Marion’s Ecosystem study (DEIMEC III and IV respectively). Macrozooplankton samples were collected using WP-2, RMT-8 and Bongo nets. Results of the hydrographic survey indicated that the region of investigation, the Polar Frontal Zone (PFZ), is an area of high mesoscale variability. During the 2004 survey the Antarctic Polar Front (APF) and the Subantarctic Front (SAF) merged to form an intense frontal feature with subsurface temperature and salinity ranging from 8.5-7.5ºC and 34.15-33.88, respectively. A cyclonic cold core eddy, believed to have been spawned from the APF, was observed during the 2005 survey. Macrozooplankton abundance and biomass ranged from 0 to 43.731 ind. m⁻³, and from 0 to 41.55 mg wwt m⁻³ respectively, during the three surveys. Among the carnivorous macrozooplankton, chaetognaths (Eukrohnia hamata and Sagitta gazellae) were most prominent, contributing up to 85% of the total biomass during all three surveys. Elevated biomass values were found near and within the frontal feature during the 2004 survey, and also along the eddy edge during the 2005 survey. However, hierarchical cluster analysis did not reveal the presence of distinct zooplankton groupings associated with the various water masses encountered during the surveys and this is probably due to the high mesoscale variability in oceanographic conditions that are characteristic of the PFZ. The total average predation impact of the selected carnivorous macrozooplankton during the 2001, 2004 and 2005 surveys accounted for 4.93 ± 6.76%, 0.55 ± 0.51% and 4.88 ± 4.45 of the mesozooplankton standing stock, respectively. S. gazellae had the highest consumption rate in all three surveys, consuming up to 800 g Dwt 1000m⁻³d⁻¹ during the study. Of the two chaetognaths, E. hamata dominated the chaetognath standing stock. The combined abundance and biomass values of E. hamata and S. gazellae ranged from 0 to 43.73 ind. m⁻³ and from 0 to 41.551 mg wwt m⁻³ respectively, during the three surveys. Inter-annual variability in the chaetognath densities was apparent. Highest abundances and biomasses tended to be associated with specific water masses, confirming the existence of a relationship between zooplankton community structure and hydrographic conditions. Generally, about 90% of the chaetognaths contained no food in their guts. S. gazellae consumed a wider variety of prey. Oil droplets occurred in the guts of ≈ 51% of E. hamata. Cannibalism was low in both species, but greater in S. gazellae than E. hamata. During the three surveys, the feeding rate values of E. hamata and S. gazellae went up to 0.48 and 2.099 prey d⁻¹ respectively. S. gazellae also had a greater predation impact on the mesozooplankton standing stock than E. hamata. The mean predation impact of the chaetognaths combined was 0.31 ± 0.291%, 0.52 ± 0.28% and 0.53 ± 0.56% of the mesozooplankton standing stock during the 2001, 2004 and 2005 surveys, respectively. During all three surveys, the majority of individuals (≈ 76%) of the chaetognaths were at stage I maturity, suggesting that during the time of study the chaetognaths were not reproducing. In both species a significant difference (log-linear analysis, p < 0.05) in maturities between the years investigated was observed. In general, there were no differences in lengths and maturities between the different water masses encountered during the surveys. The lengths of E. hamata and S. gazellae ranged from 5 to 24 mm and from 9.4 to 63.6 mm, respectively.