Diversity of Aquatic Diversity of Aquatic OrganismsOrganisms

PhytoplanktonPhytoplankton (Photosynthetic plankton, Mostly algae)(Photosynthetic plankton, Mostly algae)

Part 2Part 2

Characteristics of AlgaeCharacteristics of Algae Eukaryotic cellsEukaryotic cells Single Cellular or Multi-cellular Single Cellular or Multi-cellular

Colonies, cells have limited coordination and specializationColonies, cells have limited coordination and specialization

Most are aquatic but, some are notMost are aquatic but, some are not Lichen = (fungus + algae)Lichen = (fungus + algae)

webs.wichita.edu/mschneegurt/biol103/lecture08/lichen_micro.jpg

Most are photosynthetic, but …Most are photosynthetic, but … some are heterotrophic (colorless, parasitic)some are heterotrophic (colorless, parasitic)

Simple reproductive cellsSimple reproductive cells

Characteristics of AlgaeCharacteristics of Algae

http://www.onr.navy.mil/Focus/ocean/images/habitats/kelpai.jpg

Most are are non-vascular Most are are non-vascular and do not have tissues and do not have tissues but…but… Kelps and other seaweeds Kelps and other seaweeds

may have some degree of may have some degree of specialization in structures. specialization in structures. Still, they do not have roots, Still, they do not have roots, stems, or leavesstems, or leaves

www.pfiesteria.seagrant.org/

Pfiesteria

On the bottom (Benthic or “epipelic” algae)On the bottom (Benthic or “epipelic” algae) Good access to nutrients in sediments, but can only Good access to nutrients in sediments, but can only

be in shallow water due to light limitationbe in shallow water due to light limitation epilithic - rockepilithic - rock epipsammic - sandepipsammic - sand

Attached to aquatic macrophytes (Periphyton)Attached to aquatic macrophytes (Periphyton) Algae and animals form a community (the Aufwuchs) Algae and animals form a community (the Aufwuchs)

in the “slime” on stems of aquatic plantsin the “slime” on stems of aquatic plants

In the water column (In the water column (PhytoplanktonPhytoplankton))

Where is algae found in lakes?Where is algae found in lakes?

A Note On TerminologyA Note On Terminology

Seston - all particulate matterSeston - all particulate matter bioseston - livingbioseston - living tripton (detritus) - non livingtripton (detritus) - non living

Nekton - organisms that Nekton - organisms that create turbulence - fishcreate turbulence - fish

Plankton - organisms that are Plankton - organisms that are influenced by turbulenceinfluenced by turbulence Euplankton (truly planktonic)Euplankton (truly planktonic)

• phytoplankton (i.e., planktonic phytoplankton (i.e., planktonic algae)algae)

• zooplankton - protozoans, zooplankton - protozoans, arthropods, rotifersarthropods, rotifers

A Note On TerminologyA Note On Terminology meroplanktonmeroplankton - periodically enter the - periodically enter the

plankton. Can’t pass whole life history in the plankton. Can’t pass whole life history in the water column, live also in benthic habitats - water column, live also in benthic habitats - (insect larvae, dreissenid veliger larvae)(insect larvae, dreissenid veliger larvae)

BenthosBenthos phytobenthosphytobenthos zoobenthoszoobenthos

PhytoplanktonPhytoplankton Pigments Pigments

Often used to categorize phytoplanktonOften used to categorize phytoplankton All photosynthetic algae possess photosynthetic All photosynthetic algae possess photosynthetic

pigments.pigments.• Chlorophylls - Chla in all algae; also b and c (green pigment)Chlorophylls - Chla in all algae; also b and c (green pigment)• Carotenoids -Carotenoids - carotenes, xanthophylls (brown, gold, red)carotenes, xanthophylls (brown, gold, red)• Phycobilins - pigment - protein complexes (blue and red)Phycobilins - pigment - protein complexes (blue and red)

Similar pigments usually indicates evolutionary Similar pigments usually indicates evolutionary relationshipsrelationships

Special adaptationsSpecial adaptations FlagellaeFlagellae

• motility (slight) and feeding current generationmotility (slight) and feeding current generation

PhytoplanktonPhytoplankton Gas vacuolesGas vacuoles

• Buoyancy control (especially in blue-green algae)Buoyancy control (especially in blue-green algae) Modes of feeding Modes of feeding

• PhotosynthesisPhotosynthesis (autotrophy) (autotrophy) • HeterotrophyHeterotrophy (metabolism of organic substrates) (metabolism of organic substrates) • MixotrophyMixotrophy - both occur in the same organism. - both occur in the same organism. • Some algae graze on bacteria, then switch to photosynthesis.Some algae graze on bacteria, then switch to photosynthesis.

Nutrition Nutrition General need for nitrogen and phosphorus.General need for nitrogen and phosphorus.

• Si required by diatomsSi required by diatoms• N-fixation in blue-green algaeN-fixation in blue-green algae• vitamins - many have a requirements for B12vitamins - many have a requirements for B12

These requirements help determine where and when certain These requirements help determine where and when certain algae occuralgae occur

Taxonomic Survey of AlgaeTaxonomic Survey of Algae Blue-Green Algae

Division Cyanobacteria Oldest photosynthetic organisms on Earth Prokaryotic

• No organelles (organized nucleus, mitochondria, chloroplasts, etc)

• Functionally and physically similar to algae• Cellular structure similar to bacteria

Nutrition• Need 6 mg/L Na

Do well at high pH Some can fix molecular nitrogen (N2) May produce toxins (hepatoxins, PSTs)

Pigments Chlorophyll a, Phycobilins - Phycoerythrin (red), Phycocyanin (blue)

Blue-green Algae (Cyanobacteria)Blue-green Algae (Cyanobacteria) Important Structures

Akinites• Thick-walled resting stage, daughter colony inside

Heterocysts• Chlopophyll-free cells for N2 fixation

Gas Vacuoles• Can be produced or destroyed to change cell buoyancy

www.bact.wisc.edu/Microtextbook

HeterocystHeterocyst

AkiniteAkinite

expasy.org/spotlight/images/sptlt023.jpg

Gas Vacuoles

Blue-green Algae (Cyanobacteria)Blue-green Algae (Cyanobacteria) Common Genera

AnabaenaAnabaena

AphanizomenonAphanizomenon

OscillatoriaOscillatoria

MicrocystisMicrocystisChroococusChroococus

www.micrographia.com

Cyanobacteria Blooms in Lake ErieCyanobacteria Blooms in Lake Erie MicrocystisMicrocystis sp. sp.

Blooms form in June-SeptBlooms form in June-Sept Produces Microcystin toxinProduces Microcystin toxin Disrupt recreational use of lakeDisrupt recreational use of lake Algae washes ashore and decaysAlgae washes ashore and decays City of Toledo spends $4K/ day to remove City of Toledo spends $4K/ day to remove

MicrocystisMicrocystis from drinking water supply from drinking water supply

Lyngbya wolleiLyngbya wollei Recent problem in Lake Erie (2006)Recent problem in Lake Erie (2006) Grows on bottom in shallow watersGrows on bottom in shallow waters May Produce PSTsMay Produce PSTs Mats float to surface and wash ashoreMats float to surface and wash ashore Severe disruption of shoreline, nuisance to Severe disruption of shoreline, nuisance to

property owners and beach usersproperty owners and beach users

Characteristics Eukaryotic

• Divide by mitosis, may undergo sexual reproduction produce haploid gametes (flagellated male and female cells)

Pigments• Chlorophyll a and b organized in chloroplasts• Carotenoids in some species

Very Diverse• Typical lake may have 80-100 phytoplankton species (1/2 of

them are green algae) Most similar to higher plants

Green Algae (Chlorophyta)Green Algae (Chlorophyta)

Examples Volvox sp.

• colonial• Flagellated cells

in mucilage matrix

• Daughter colonies within parent colony

Green Algae (Chlorophyta)Green Algae (Chlorophyta)

Colonies in black dye to highlight mucilage matrix