Transcript Algae and Microinvertebrates

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 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
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
Lentic Zones
Lotic Environments
Lotic Environments
Community Descriptions
• Neuston – organisms floating in surface
film of water
• Pleuston – organisms living at thin airwater 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 N2 from
atmosphere
Cyanobacteria
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
Spirogyra
(Genus of Green Algae)
Euglenoids
• Phylum 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
Euglena
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)
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
Diatoms
Gyrosigma obtusatum
Pleurosira laevis
Nitzschia levidensis
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 immature copepods
before reaching maturity
– Characterized by conspicuous
1st 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