Protozoa

1. Protozoa Objective: To know the basic cytology and characteristics of protozoa. Understand their importance in the ecology of water treatment and significance as pathogens in water supply. References Sleigh, M. Protozoa and other Protists Curds, C.R. Protozoa in the Water Industry Mitchell, R Environmental Microbiology Gray, N F Biology of Wastewater Treatment Outline Introduction, Classification, Characteristics, Water Ecology, Water Pathogens.

2. Protozoa - Introduction • Members of Protista kingdom • Eukaryotic mostly Unicellular • Reproduce - sexually (Conjugation) asexually (Binary Fission) • Motile (not all) • swimming, gliding, crawling • May have Plastids (Algae?) • these can be lost • Size 5 m - > 500 m • Extremely Diverse Morphology • c.f. bacteria, fungi

3. Morphology • Nucleus in nuclear membrane • 1 or 2 nuclei • Cytoplasmic Membrane • Present in all • Organelles often present • mitochondria, golgi, Chloroplasts! • Cell Wall - Absent • Cell Coat / Shell • Pellicle • Test • Lorica • Cilia, Cirri • Flagella • Contractile Vacuole • in free-living protozoa

4. Feeding • Autotrophs (Phototrophic) • Primary producers like Algae • Heterotrophs • Saprobic - dead and decaying matter • Holozoic - whole live organisms • bacteria, algae, other protozoa • Raptorial Feeding • Actively seek prey (Didinium) • Filtration • Cilia beat, cilia trap (Vorticella) • Buccal Cavity (Mouth region) • Cytostome - Phagocytosis • Stick to Prey • Suctoria tentacles with haptocyst (Acineta) • suck contents of cell • Pinocytosis - cell drinking • soluble organics

5. Sarcomastigophora • Mastigophora subphylum having flagellum • Phytomastigophora • phototrophic flagellates • can lose chloroplasts • e.g. Euglena, Peranema • Zoomastigophora • animal-like flagellates • e.g. Bodo, Oikomonas • some parasitic e.g. Giardia*,Trypanosoma* • Sarcodinasubphylum having pseudopoda • Rhizopoda • move by pseudopoda • Naked - Amoeba, Entamoeba* • Testate - Arcella • Actinopoda • planktonic • Radiolaria • radial axopoda, siliceous skeleton. `

6. Apicomplexa • Sporozoea • simple , resistant spores and oocysts • parasitic • e.g. Cryptosporidium* Plasmodium (malaria)* Toxoplasmosis* Microsporidia Myxosporidia • Obligate intracellular parasites • in vertebrates, invertebrates, protists • e.g. Nosema disease in Honey bees

7. Ciliophora The major Phylum in terms of diversity and actual numbers in Aquatic Environments. A number of sub-classes, all have cilia or ciliary organelles. Most are free-living. Four types are of most interest. • 1. Suctoria • Predatory on other protozoa, sessile. • no cilia, but have tentacles. • e.g. Acineta, Podophyra • 2. Peritrichia • Sessile usually stalked. • Bell-shaped pellicle, some have lorica. • Cilia bands. • e.g. Vorticella Carchesium Opercularia

8. Ciliophora • 3. Holotrichia • free-swimming • body covered in cilia • some predatory • e.g. Paramecium Chilodonella Colpidium • 4. Spirotrichia • cilia in rows, sheets, tufts, - i.e. Cirri • Crawl on surfaces • e.g. Aspidisca Euplotes

9. Ecological Function • Surface waters • Sewage treatment • primary feeders • holozoic - bacterial predation • particulate ingestion (detritus) • uptake of dissolved BOD • Benefits • Purification • Clarified effuents • Pathogen Removal

10. Ecological FactorsAffecting Protozoa • Water • essential, Encyst when shortage. • Temperature • Survive extremes by spores or cysts. • Oxygen • free-living species mostly aerobic • gut parasites, symbionts anaerobic. • Carbon Dioxide • high conc. toxic to many species • Paramecium, & Bodo tolerant, find them with pollution. • Salinity • Strong effect on water uptake by cell. • Contractile vacuole compensates. • most species either fresh- or saltwater.

11. Saprobic Zones - Protozoascheme of Kolkwitz & Marsson (1902) • 1. Polysaprobic (large numbers small diversity) BOD (10 - 50 mg/l) Bodo, Oikomonas, Paramecium • 2. Mesosaprobic (greater diversity, + pigmented flagellates) - BOD (5 - 10 mg/l) - BOD (2.5 - 5 mg/l) Chladydomonas (pigmented flagellate) Chilomonas (flagellate) Colpidium (ciliate) Arcella (amoebae) • 3. Oligosaprobic photosynthetic protozoa BOD (< 2.5 mg/l) Dinobryon Ceratium + ciliates and amoebae (limited application due to the lengthy identification process)

12. Protozoal Diseases • Giardiasis - Giardia lamblia • flagellate, symmetrical organelles • waterborne epidemics, 106 cases/yr giving diarrhoea, nausea, cramps. • adhesive disc attaches to gut wall • animals and humans • transmission through faeces • cysts resistant to chlorination • 108 cysts/g faeces • infectious dose 25 cysts • Filtration best method for removal • Cryptosporidiosis -Cryptosporidium sp. • only recently identified epidemiology • Sporozoan oocysts • Cow faeces (177days 40% viable) • 1989 Reading outbreak • 1993 Milwaukee 419,000 infected. • filtration best prevention

13. Protozoal Diseases • Trypanosomes flagellates • T.cruzi Chagas Disease • South America • animals and man • Bugs faeces enters Infants Eyes • fatal • T. brucei African Sleeping Sickness • Tsetse fly vector • invade cerebrospinal fluid and brain • fatal • Amoebic Dysentery • Rhizopod Entamoeba histolytica • mild infection (gut lumen) • severe (gut wall) • abscess, metastases in liver • warm climates increase incidence of the latter condition.

14. Protozoal Diseases • Malaria Plasmodium malariae • Sporozoan • Complex life cycle Mosquito vector, liver cells and blood cells. • Synchronised erythrocyte lysis • 72 hourcycle of fever • Prophylactic drugs for blood cells • Liver infection resistant - recurrent • Leishmanias (flagellates) • Oriental Sore - Sand Fly vector • local abscess • Kala-azar • tissue parasite • liver, spleen, bone marrow • Naegleria fowleri • Primary Amoebic Meningoencephalitis PAM • Watersports, Roman Baths + sewage contamination • death 7 days , headaches, fever, encephalitis • Can harbour Legionella in water tanks

16. Algae • Objective • To know the main cellular features of algae. • To understand the importance of algae to the process of nutrient cycling in aquatic environments. • References • Gray N.F. Biology of Wastewater Treatment • Madigan M.T., Martinko J.M., Parker J. Biology of Microorganisms • Round F.E. The Biology of the Algae

17. Outline Introduction Algal Cell Structure Characteristics of Freshwater Algae Natural Waters Benefits and Problems Environmental Factors Effluent Treatment Activated Sludge and Trickling Filters Waste Stabilization Ponds

18. Introduction • What are Algae? • Eukaryotic organisms • Bacillariophyta, Chlorophyta, Phaeophyta, Rhodophyta • Prokakyotic • Blue-green algae or cyanobacteria • Unicellular, Colonial, Multicellular • Phototrophic (photoheterotrophs, photoautotrophs) • Importance in Environmental Engineering • Primary Production • Oxygenation • Waste Stabilisation Ponds Phosphorus removal Nitrogen removal BOD removal

19. Cellular Characteristics • Size and Shape • variable • Movement • Phototrophic (eye-spot) • flagella • cell buoyancy/density • Reproduction • Asexual 1. binary fission 2. protoplast released as a Zoospore, germinates. • Sexual • not in cyanobacteria • gametes (motile like flagellates)

20. Waste Stabilisation Ponds • Anaerobic Ponds • untreated sewage • 100,000 mg BOD/m3.d • Chlamydomonas on surface • poor light penetration • Facultative Ponds • effluent from anaerobic ponds • 10,000 mg BOD/m3.d • Vertical Stratification of biological activity • Healthy Algal populations, appear green • Chlamydomonas, Euglena, Chlorella (non-motile) • Oxygenation Effects • diurnal • bacterial oxygen supply (Mutualism)

21. Waste Stabilisation Ponds • MaturationPonds • less vertical stratification of algae • more diverse algal populations • filamentous species beneficial • rate of BOD removal lower • Nitrogen removal • Phosphorus removal • Pathogen removal • elevated temperature • elevated pH • oxygen radicals

22. Eutrophication Sewage Effluents Farm Effluents Industrial Effluents Algae stimulated by increased phosphorus and nitrogen levels. Populations change from Diatoms to Blue-Greens Increased risk of Toxins from Microcystis and Anabaena