Purely qualitative investigations of the plankton of an area cannot provide sufficient information for the full understanding of the seasonal changes that oocur nor of the interrelation of the various planktonic plants and animals. Quantitative data must be obtained before these can be properly described. Except for the qualitative records by Scott (1906, 19(7) and Hiddell (1914) the plankton of waters off the north ooast of Wales, and of the Menai Straits in particular, has tended to be neglected. The unusual hydrographic conditions of the Menai Straits, which connect areas whose fauna and flora show considerable differences (Crisp & Knight-Jones, 1953) suggested such studies would be rewarding. In describing the various populations the policy in the present work has been to give the details of the most numerous species of both plants and animals individually and to summarize the others in various groups. This simplified the description and discussion of the dynamics of the population, which would be difficult to follow if all species were described in detail. At an early stage in the investigations it became obvious that the plankton of these coastal waters differed considerably from that of the Irish Sea in general, which has been described by Williamson (1956). In particular tho copepods Oithonina nana (Giesbrecht) and Euterpina acutifrons (Dana) were prominent species in the Menai Straits. Euterpina acutifrons was found to have several points of interest. Firstly, dimorphism occurs in the male; this has received considerable attention and has been found to be of some significonce in the biology of the species. Secondly, Euterpina is pelagic, while most other harpacticoid copepods are benthic or littoral. Investigations of its development (which was inadequately described by Tesch (1915)) in culture allowed a consideration of the adaptive modifications of Euterpina to a pelagic existence, of its rate of growth and development, and of the developmental aspects of dimorphism in the male. The latter has been a controversial subject in previous studies of copepod development (Sewell, 1912, 1929, 1940; Gurney, 1929; Coker, 1934) . Thirdly, Euterpina has a world-wide distribution, mainly centered in the warmer seas. Consideration of this led to investigations of some aspects of the relationship between the environment and the development of the species and also to a comparison of its breeding season in the waters round Anglesey with those reported in other latitudes . The present work also includes studies of the larval development of Oithonina nana, another warm water form. Despite its being a very common plankton animal, the larval. development of this species has tended to be neglected. In the work as now presented the studies of these species are given a considerable proportion of the total space, since the data provided on their development, growth and breeding illuminate the general study of the plankton which, in turn, forms a background to the detailed studies. The form of presentation of this thesis may perhaps call for some explanation. The sections into which it is divided have been prepared in the form of separate papers intended for publication. This means that figures and tables are numbered oonsecutively within each section and not continuously throughout the thesis, and also that a separate bibliography will be found at the end of each section. It is hoped that this method of presentation will cause no inconvenience to the reader.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:580373 |
| Date | January 1960 |
| Creators | Haq, Syed Mazharul |
| Publisher | Bangor University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://research.bangor.ac.uk/portal/en/theses/seasonal-changes-in-the-plankton-of-inshore-waters(27b5b0c0-0884-4d36-a2c1-a70e67cb3bbf).html |
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