Algae and Microinvertebrates

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Algae and Microinvertebrates
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Habitat Communities
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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.

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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

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Phytoplankton

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

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Phytoplankton

• Phylogenetically diverse
• Important groups
• cyanobacteria
• dinoflagellates
• euglenoids
• green algae
• diatoms

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Lentic Zones
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Lotic Environments
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Lotic Environments
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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

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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

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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)

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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

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Blue-Green Algae

• Heterocysts fix N2 from atmosphere

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Cyanobacteria
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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

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Green Algae

• Notes
• Cell walls of cellulose and nuclear membrane
  present
• May possess 2 or 4 flagella

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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

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Green Algae

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

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Spirogyra(Genus of Green Algae)
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Euglenoids

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

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Euglenoids

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

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Euglena
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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)

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Yellow-Green Algae

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

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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)

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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
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Diatoms Order Centrales

• Characterized by centric and often circular form
• Note also the numerous punctae (pores)

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Diatoms Order Pennales

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

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Diatoms
Gyrosigma obtusatum
Pleurosira laevis
Nitzschia levidensis
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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

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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
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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

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Red Algae

• Notes
• In MI, found in bogs/attached to logs in
  streamscan be locally common

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Dinoflagellates

• Phylum Pyrrhophyta
• Whirling flagella
• Habitat Mostly marine, some freshwater
• Notes
• Unicellular protists
• 2 dissimilar flagella
• Many are photosynthetic

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Dinoflagellates

• Notes
• Heterotrophic dinoflag feed on diatoms or other
  protists
• Marine blooms
• Red tides

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Rotifers

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

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Rotifers

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

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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

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Bryozoa
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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

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Cladocera

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

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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

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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

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The End