Algae and Microinvertebrates ENV 311 / EEB 320 Winter 2007

Habitat & Communities

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.

Phytoplankton Basis for aquatic food chain b/c major primary producers Huge impact on global primary production –Estimated at 10 5 – 10 6 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

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

Phytoplankton Phylogenetically diverse Important groups: –cyanobacteria –dinoflagellates –euglenoids –green algae –diatoms

Cyanobacteria

Dinoflagellates

Euglena

Diatoms Pleurosira laevis Nitzschia levidensis Gyrosigma obtusatum

Spirogyra (Genus of Green Algae)

Lentic Zones

Lotic Environments

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

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

Algae and Microinverts 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)

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

Blue-Green Algae Heterocysts fix N 2 from atmosphere

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

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

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

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

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

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

Phylum Heterokontophyta Algae having chlorophyll a and usually c, and flagella of unequal lengths Classes –Xanthophyceae –Chrysophyceae –Bacillariophyceae –Phaeophyceae

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

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)

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

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

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

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

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

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

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

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

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

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

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

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

Bryozoa

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

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

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 nauplii before reaching maturity –Characterized by conspicuous 1 st pair of antennae and single anterior eye

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

The End

Phylum Cnidaria/Coelentaria Corals, hydroids, sea anemones, & jellyfish –Habitat: Marine, freshwater (Hydra) –Notes: Radial symmetry Nematocysts Two staged life cycle –Polyp (“juvenile”) –Medusa (“adult”) Symbiosis w/plants in corals.

Phylum Cnidaria/Coelentaria Notes: Freshwater ecosystems: Hydra