Physiological ecology of Lough Neagh phytoplankton

Abstract

The annual cycle of phytoplankton in Lough Neagh has been described in Chapter 10 with two species of blue-green algae dominating the phytoplankton except for a short period during the spring diatom bloom. The regularity of this cycle, with Oscillatoria redekei dominant during the spring and early summer, giving way to Oscillatoria aghardii for the remainder of the year suggests that the cycle may be controlled by seasonal changes in light or temperature or a combination of the two. Because of high external nutrient loadings to Lough Neagh (Chapter 8), nutrient limitation may play only a subordinate role in the succession of these species. The aim of this chapter is to describe laboratory experiments which have been undertaken to investigate how the growth rates and cell composition of Oscillatoria redekei and Oscillatoria agardhii are determined by irradiance, day length and temperature. Additional studies have been carried out on Aphanizomenon flos-aquae and Anabaena flos-aquae, two potentially nitrogen fixing species which have been virtually absent from the phytoplankton since 1976 (Chapter 10). The results of these studies will be compared with changes in the species dominance observed in Lough Neagh.KeywordsDark PeriodMaximum Growth RateContinuous LightHigh IrradiancePhotic ZoneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.