Studies on the effect of food quality on the growth dynamics of the copepod <i>Acartia tonsa</i> were conducted using various algal treatments grown under a number of different nutrient regimes. Populations of the copepod <i>A. tonsa</i> were fed algal prey (diatoms <i>Thalassiosira weissflogi </i>and<i> T. pseudonana</i>, prymnesiophyte <i>Emiliania huxleyi</i>, dinoflagellate <i>Aureodinium pigmentosum</i>) grown under different nutrient regimes, in order to study the impact of food quality on production and development throughout the life cycle of the copepod. Changes in predator population structure and biomass were recorded, along with consumption of each of the algal groups, permitting carbon and nitrogen growth efficiencies to be estimated. There was a clear difference in the <i>Acartia tonsa</i> population structure when fed nitrogen-sufficient or nitrogen-deplete prey, with those fed nitrogen-deplete prey slower to develop and reproduce and laying fewer eggs. Algal nutrient status affected selectivity between the diatom and dinoflagellate, the latter being favoured under nutrient-deplete conditions, perhaps in part because their carbon:nitrogen ratio was less susceptible to altered nutrient status. Copepod production was found to be extremely poor when fed diatoms, with lower egg production, poorer hatching success, juveniles smaller and more lethargic and less likely to grow. Although diatoms were found to be nutritionally inferior to the other prey species, even a small proportion of non-diatom (dinoflagellate) had a disproportionately positive effect. Diatoms do therefore have a significant role to play in mixed diets. Growth efficiencies increased with time during the progression to later life history stages, culminating in highest efficiencies during active egg production.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637733 |
| Date | January 2004 |
| Creators | Jones, R. H. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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