hartmannii were aligned with P. schwartzii and P. kofoidii but was not observed in the alignment between P. hartmannii and P. lebourae. Using scanning electron microscopy, several morphological features previously not reported for P. hartmannii were observed: a ventral groove located in the sulcus, a deep arc-like apical concavity within the area of apical groove, scale-like vesicles, and a shallow, completely enclosed, loop-like apical groove. Resting cysts with arrow-like surface spines were produced heterothallically by crossing clonal isolates and germinated single gymnoid cells. Finally, filtered and unfiltered bloom water from
the Forge River and clonal cultures of P. hartmannii exhibited acute ichthyotoxicity to juvenile sheepshead minnows (Cyprinodon variegates) and aeration did not mitigate this effect, suggesting P. hartmannii Ku-0059436 mouse is an ichthyotoxic, harmful alga. “
“The preference of phytoplankton for ammonium over nitrate has traditionally been explained by the greater metabolic
cost of reducing oxidized forms of nitrogen. This “metabolic cost hypothesis” implies that there should be a growth disadvantage on nitrate compared to ammonium or other forms of reduced nitrogen such as urea, especially when light limits growth, but in a variety of phytoplankton taxa, this predicted difference has not been observed. Our experiments with three strains of marine Synechococcus (WH7803, WH7805, and WH8112) did not reveal consistently faster growth (cell division) on ammonium or urea as compared to nitrate. Urease and glutamine synthetase (GS) activities varied with nitrogen source in a manner consistent with regulation BIBW2992 chemical structure by cellular nitrogen status via NtcA (rather than by external availability of nitrogen) in all three strains and indicated that each strain experienced some degree of nitrogen insufficiency during growth MCE on nitrate. At light intensities that strongly limited growth, the composition (carbon, nitrogen, and pigment quotas) of WH7805 cells using nitrate was indistinguishable
from that of cells using ammonium, but at saturating light intensities, cellular carbon, nitrogen, and pigment quotas were significantly lower in cells using nitrate than ammonium. These and similar results from other phytoplankton taxa suggest that a limitation in some step of nitrate uptake or assimilation, rather than the extra cost of reducing nitrate per se, may be the cause of differences in growth and physiology between cells using nitrate and ammonium. “
“The last two decades have witnessed increasing episodes of lesser flamingo die-offs in East Africa. Based on data on phytoplankton composition, biomass, and flamingo population density in three alkaline-saline lakes of Kenya (Bogoria, Nakuru, and Oloidien) in 2001–2010, this study explored the link between sudden flamingo deaths and fluctuations in algal food quantity and quality. The phytoplankton biomass ranged from 13 to 768 mg · L−1.