Chrysophyte reproduction and resting cysts: A paleolimnologist's primerSandgren, Craig
doi: 10.1007/BF00226555pmid: N/A
Chrysophyte algae produce siliceous resting cysts (stomatocysts) that are becoming an increasingly useful class of paleoecological indicator microfossils. This paper provides a review of the role that stomatocysts play in the life cycle and reproductive ecology of freshwater planktonic chrysophytes. Such information provides paleolimnologists with greater insight into the ecology of the vegetative, planktonic growth phase of species contributing stomatocysts to lacustrine microfossil assemblages. Specific chrysophyte reproductive characteristics discussed include: temporal dynamics of vegetative growth and encystment, cyst induction, cyst survivorship, germination requirements and recruitment strategies. This information serves as an introduction to a special issue of the Journal of Paleolimnology which is dedicated to the ‘Application of Chrysophyte Stomatocysts in Paleolimnology’.
The stomatocyst of Mallomonas acaroides v. muskokana (Chrysophyceae)Siver, Peter
doi: 10.1007/BF00226556pmid: N/A
The stomatocyst of Mallomanas acaroides v. muskokana is described based on observations made from both live populations and surface sediment remains. The cyst is slightly ovate in shape, covered with evenly spaced, ornamented spines and has a short cylindrical collar with a variable apex and internal annulus surrounding the pore. The spines have a thickened base, a cylindrical middle section and a flattened apex with a ring of finger-like projections. Several immature stages of development are described and the stomatocyst is compared to those described for phylogenetically similar species. Complementary investigations of stomatocysts from both living (planktonic) and sediment collections can greatly facilitate the identification of stomatocyst morphotypes.
Sedimentary chrysophycean cyst assemblages as paleoindicators in acid sensitive lakesRybak, Mariusz; Rybak, Izabela; Nicholls, Kenneth
doi: 10.1007/BF00226557pmid: N/A
Relationships between surface sediment cyst assemblages and lakewater characteristics were studies in 50 lakes located in central Ontario. The main purposes of the study were to identify the environmental factors most strongly controlling the distribution of chrysophycean cysts and to develop indices and equations to infer lake water pH from cyst assemblages. Principal components analysis indicates that alkalinity and associated TDS as well as elements related to trophic status are the factors most strongly correlated with the distribution of chrysophycean cysts. There are significant differences in the relative importance of these factors among the lakes. The transfer functions developed provide good prediction of pH values. This report also provides a descriptive analysis of the ‘fossil’ chrysophycean cyst flora of Ontario lakes. The descriptions include representative SEM micrographs and detailed characterization of each morphotype in consideration of the morphological variation observed among specimens of the same morphotype. Special attention has been paid to the anatomy of the collar complex and to the nature of the cyst surface ornamentation. One hundred and thirty seven morphotypes are described.
Morphological descriptions and stratigraphic distributions of the chrysophycean stomatocysts from a recently acidified lake (Adirondack Park, N.Y.)Duff, Katharine; Smol, John
doi: 10.1007/BF00226558pmid: N/A
The chrysophycean stomatocyst flora from the sediments of Upper Wallface Pond, a recently acidified Adirondack lake, was described according to the guidelines of the International Statospore Working Group. Sixty-six morphotypes were distinguished, using scanning electron microscopy. Twenty-eight of these cysts were distinguishable using the light microscope (LM), whereas 30 required grouping into 11 collective categories from LM identification, and 7 could not be identified using LM. None of our morphotypes could be linked definitively to the living chrysophyte species that produced them. Stratigraphic analysis showed that a marked change in the cyst assemblage occurred in the 1930's. Previous paleoecological studies inferred a pronouced pH decline at this time. Redundancy analysis of our data showed that diatom-inferred pH explained a significant amount of variation (Monte Carlo permutation test; p=0.01). This suggests that pH influences chrysophyte populations, and that stomatocysts could eventually be used to reconstruct pH and other variables.