Algae and Microinvertebrates

1. Algae and Microinvertebrates ENV 311 / EEB 320 Winter 2007

2. Habitat & Communities

3. Phytoplankton • Phytoplankton – microscopic plants and some types of bacteria which obtain their energy via photosynthesis. • Important to the ecosystem because • Part of the primary producing community • Assist in recycling elements such as carbon and sulfur which are required elsewhere in the community.

4. Phytoplankton • Basis for aquatic food chain b/c major primary producers • Huge impact on global primary production • Estimated at 105 – 106 g C/year • More abundant in well-lighted areas with higher temperatures • Relatively unspecialized physiology, but are evolved to maintain buoyancy • Very little competitive exclusion • May be unicellular or multicellular

5. Phytoplankton • Asexual reproduction keep numbers high • Cyanobacteria can double several times/day • Diatoms are slower, but can double every 1-2 weeks

6. Phytoplankton • Phylogenetically diverse • Important groups: • cyanobacteria • dinoflagellates • euglenoids • green algae • diatoms

7. Lentic Zones

8. Lotic Environments

9. Lotic Environments

10. Community Descriptions • Neuston – organisms floating in surface film of water • Pleuston – organisms living at thin air-water interface (bodies project into air) • Periphyton – organisms living attached underwater surfaces

11. Periphyton • Sessile organisms, such as algae and small crustaceans, that live attached to surfaces projecting from the bottom of a freshwater aquatic environment. • Major groups include: • cyanobacteria • diatoms • filamentous green algae

12. Cyanophyta Chlorophyta Euglenophyta Heterokontophyta Xanthophyceae Chrysophyceae Bacillariophyceae Phaeophyceae Oomycetes Rhodophyta Pyrrhophyta Rotifera Ectoprocta/Bryozoa Arthropoda Crustacea (superclass) Cladocera (suborder) Copepoda (order) Chelicerata (subphylum) Arachnida (superclass) Acari (order) Algae and Microinverts

13. Blue-Green Algae • Phylum Cyanophyta • Habitat: widespread in marine and fresh water • Notes: • Prokaryotic; no nuclear membrane or organelles • Lacks cellulose cell walls and flagella • Uses chlorophyll A, biliproteins, and carotenoids • May be colonial, filamentous, unicellular • Moves by extruding mucus

14. Blue-Green Algae • Heterocysts fix N2 from atmosphere

15. Cyanobacteria

16. Green Algae • Phylum Chlorophyta • Habitat: widespread in marine and fresh water • Notes: • Very diverse group, hard to generalize about their ecology • May be unicellular, filamentous or colonial

17. Green Algae Notes: • Cell walls of cellulose and nuclear membrane present • May possess 2 or 4 flagella

18. Green Algae • Notes: • Utilize cholorphyll A/B and carotenoids • Store energy as starch • Some forms are large (e.g. Chara spp.) and at first glance resemble a higher plant

19. Green Algae • Notes: • Some are good indicators of either nutrient rich (Cladophora spp.) or poor (Desmidae) environments

20. Spirogyra(Genus of Green Algae)

21. Euglenoids • Phylum Euglenophyta • Habitat: freshwater • Notes: • Mostly unicellular with 1-3 flagella • Nuclear membrane but no cell walls

22. Euglenoids Notes: • Found mostly in still water • Can be auto- or heterotrophic • Abundance of heterotrophic forms may be indicative of pollution

23. Euglena

24. Phylum Heterokontophyta • Algae having chlorophyll a and usually c, and flagella of unequal lengths • Classes • Xanthophyceae (yellow-green algae) • Chrysophyceae (golden algae) • Bacillariophyceae (diatoms) • Phaeophyceae (brown algae)

25. Yellow-Green Algae • Class Xanthophyceae • Habitat: Primarily in freshwater, but some marine. • Abundance: Not abundant • Notes: Contains chlorophyll c (NO chlpyll b)

26. Golden Algae • Class Chrysophyceae • Habitat: fresh water • Notes: • With or without chloroplasts; chloroplast yellowish green or yellowish brown due to a large amount of beta carotin and xanthophyll, also contains chlorophyll a and c • Facultative heterotrophs (in the absence of light)

27. Diatoms • Habitat: Marine & freshwater • Notes: • ~20-25% of all organic carbon fixation carried out by diatoms • Single celled • Produces a frustule made of silica. • Bilateral symmetry • Radial symmetry Class Bacillariophyceae

28. Diatoms: Order Centrales • Characterized by centric and often circular form • Note also the numerous punctae (pores)

29. Diatoms: Order Pennales • Usually elongate • Characterized by numerous striae (grooves) that may run both parallel and perpendicular to the axis of the organism

30. Diatoms Gyrosigma obtusatum Pleurosira laevis Nitzschia levidensis

31. Brown Algae • Class Phaeophyceae • Habitat: mostly marine and littoral eukaryotic algae • Notes: • Some of the kelps can grow to enormous sizes, forming “kelp forests,” and hosting a unique fauna • Multicellular • Contains slimy mucilaginous materials

32. Water Molds • Class Oomycota “Egg fungus” • Habitat: Freshwater • Notes: • Does not contain chlorophyll • Are heterotrophic • Produces gametes • Cell wall composed of a mix of cellulosic compounds • Nuclei are diploid (not haploid as in fungi) End Phylum Heterokontophyta

33. Red Algae • Phylum Rhodophyta • Habitat: primarily marine but some fw • Notes: • Uses Chlor A/D, carotenoids and biliproteins • No flagellated life stage • Able to photosynthesize at very low light levels and wide range of the spectrum

34. Red Algae Notes: • In MI, found in bogs/attached to logs in streams—can be locally common

35. Dinoflagellates • Phylum Pyrrhophyta “Whirling flagella” • Habitat: Mostly marine, some freshwater • Notes: • Unicellular protists • 2 dissimilar flagella • Many are photosynthetic

36. Dinoflagellates Notes: • Heterotrophic dinoflag feed on diatoms or other protists • Marine “blooms” • Red tides

37. Rotifers • Phylum Rotifera “Rotating wheel” • Habitat: Fresh water • Notes: • Heterotrophic • Corona of cilia provide movement and means to move food toward the mouth.

38. Rotifers Notes: • Sessile, anchors itself with foot • May enter dormancy and form cyst when env. conditions unfavorable • Cysts last up to 50 years

39. Bryozoa • Phylum Ectoprocta (=Bryozoa) • “Moss animals” • Habitat: Marine and both lotic/lentic freshwaters • Notes: • Sessile; can be epiphytic, epilithic or epidendric • Colonial; a number of clones inhabit one structure • Extend ciliated tentacles to filter food from water • Often host a number of smaller organisms

40. Bryozoa

41. Cladocera • Phylum Arthropoda, Superclass Crustacea, Suborder Cladocera • Water fleas or Daphnia • Habitat: widespread; very important in lentic habitats • Notes: • Uses antennae to swim • Many populations react to diurnal cycles, making vertical migrations each day • May be predacious or herbivorous • Head varies considerably from rounded to hooded but eye spot is always distinctive • Body laterally compressed

42. Cladocera • Notes • Parthenogenetic: • most eggs are diploid females (asexual repro) • occasional diploid males fertilize haploid eggs produced by females for sexual reproduction

43. Copepods • Phylum Arthropoda, Superclass Crustacea, Order Copepoda • Habitat: widespread in marine and fw; may be benthic or pelagic • Notes: • may be parasitic, predacious or detrivorous • often seen carrying egg sacs on both sides • develop through several stages as immature copepods before reaching maturity • Characterized by conspicuous 1st pair of antennae and single anterior eye

44. Acari (Water Mites) • Phylum Arthropoda,Subphylum Chelicerata, Superclass Arachnida, Order Acari • Habitat: most abundant in lotic waters • Notes: • Have 6 legs when young, 8 when mature • Many are parasitic but a few are predaceous • Possess no antennae • Related to terrestrial spiders

45. The End