- Small group of few, mainly marine genera
- Appearance: 30-80 µm, long anterior flagellum with perpendicular tripartite hairs, smooth flagellum motionlessdirected backwards; naked cells without scales or cell cover
- Trichocysts can be ejected and produce long mucilaginous strands
- Mucocysts can produce extracellular mucilage
- Metabloy is documented for some species
- Pigments: Chlorophyll a and c, but some species lack chl.c; marine species possess fucoxanthin and violaxanthin, whereas freshwater forms possess diadinoxanthin and others
- Pyrenoids in marine but not freshwater sp.
- Phototrophic, phagotrophy and sexual reproduction not observed
-
Fish
kills are cause by blooms of Heterosigma
and Olisthodiscus (marine)
- Name: gr. Chrysos = gold; „golden algae“;
- Color golden brown by their predominant accessory pigment fucoxanthin
- Appearance: unicellular flagellates or flagellated colonies, sometimes non-motile unicells, colonies, or amoeboid stages that produce flagellated spores
- Habitat: mostly freshwater, but also marine species; prefer slightly acidid water (pH<7), probably because they posses an acidic but no alkaline phosphatase (enzyme to degrade organic phosphates); abundant in the periphyton (communities living on macroalgae)
- Stomatocysts are heavily silicified resting stages resulting from sexual or asexual reproduction; fossil records of chrysophycean stomatocysts and their distinct surface structure (electron microscope) are used for geological studies; only 10% of stomatocysts have been connected to vegetative taxa
- Nutrition in Chrysophytes
-
Nutrition:
most species mixotroph, among them chlorophyll-containing
species that act primarily as heterotrophs and use photosynthesis only
in times of scarce food supply
Dependence of Ochromonas growth on bacteria abundance - Important grazers on bacteria and picoalgal communities in freshwater and marine systems
- Freshwater blooms of chrysophyceans can cause fish kills by toxins or gill clogging
- Water odor can arise from excretion of ketons and aldehydes by chrysophyceans
- Hydrurus foetidus Kirschner (1618)
Olive-green, feathery tufts, 1-30 cm. long, develops an offensive odor sticky to touch; occasionally encrusted with calcium carbonate; in running, cold fresh water.
