Diversity of Aquatic Organisms Phytoplankton (Photosynthetic plankton, Mostly algae) Part 2

Characteristics of Algae  Eukaryotic cells  Single Cellular or Multi-cellular Colonies, cells have limited coordination and specialization Colonies, cells have limited coordination and specialization  Most 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 … some are heterotrophic (colorless, parasitic) some are heterotrophic (colorless, parasitic)  Simple reproductive cells Characteristics of Algae  Most are are non-vascular and do not have tissues but… Kelps and other seaweeds may have some degree of specialization in structures. Still, they do not have roots, stems, or leaves Kelps and other seaweeds may have some degree of specialization in structures. Still, they do not have roots, stems, or leaves Pfiesteria

 On the bottom (Benthic or “epipelic” algae) Good access to nutrients in sediments, but can only be in shallow water due to light limitation Good access to nutrients in sediments, but can only be in shallow water due to light limitation epilithic - rock epilithic - rock epipsammic - sand epipsammic - sand  Attached to aquatic macrophytes (Periphyton) Algae and animals form a community (the Aufwuchs) in the “slime” on stems of aquatic plants Algae and animals form a community (the Aufwuchs) in the “slime” on stems of aquatic plants  In the water column (Phytoplankton) Where is algae found in lakes?

A Note On Terminology  Seston - all particulate matter bioseston - living bioseston - living tripton (detritus) - non living tripton (detritus) - non living  Nekton - organisms that create turbulence - fish  Plankton - organisms that are influenced by turbulence Euplankton (truly planktonic) Euplankton (truly planktonic) phytoplankton (i.e., planktonic algae)phytoplankton (i.e., planktonic algae) zooplankton - protozoans, arthropods, rotiferszooplankton - protozoans, arthropods, rotifers

A Note On Terminology meroplankton - periodically enter the plankton. Can’t pass whole life history in the water column, live also in benthic habitats - (insect larvae, dreissenid veliger larvae) meroplankton - periodically enter the plankton. Can’t pass whole life history in the water column, live also in benthic habitats - (insect larvae, dreissenid veliger larvae)  Benthos phytobenthos phytobenthos zoobenthos zoobenthos

Phytoplankton  Pigments Often used to categorize phytoplankton Often used to categorize phytoplankton All photosynthetic algae possess photosynthetic pigments. All photosynthetic algae possess photosynthetic pigments. Chlorophylls - Chla in all algae; also b and c (green pigment)Chlorophylls - Chla in all algae; also b and c (green pigment) Carotenoids -carotenes, xanthophylls (brown, gold, red)Carotenoids -carotenes, xanthophylls (brown, gold, red) Phycobilins - pigment - protein complexes (blue and red)Phycobilins - pigment - protein complexes (blue and red) Similar pigments usually indicates evolutionary relationships Similar pigments usually indicates evolutionary relationships  Special adaptations Flagellae Flagellae motility (slight) and feeding current generationmotility (slight) and feeding current generation

Phytoplankton Gas vacuoles Gas vacuoles Buoyancy control (especially in blue-green algae)Buoyancy control (especially in blue-green algae) Modes of feeding Modes of feeding Photosynthesis (autotrophy)Photosynthesis (autotrophy) Heterotrophy (metabolism of organic substrates)Heterotrophy (metabolism of organic substrates) Mixotrophy - both occur in the same organism.Mixotrophy - 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 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 algae occur These requirements help determine where and when certain algae occur

Taxonomic 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 (N 2 ) May produce toxins (hepatoxins, PSTs)   Pigments Chlorophyll a, Phycobilins - Phycoerythrin (red), Phycocyanin (blue)

Blue-green Algae (Cyanobacteria)   Important Structures Akinites Thick-walled resting stage, daughter colony inside Heterocysts Chlopophyll-free cells for N 2 fixation Gas Vacuoles Can be produced or destroyed to change cell buoyancy Heterocyst Akinite expasy.org/spotlight/images/sptlt023.jpg Gas Vacuoles

Blue-green Algae (Cyanobacteria)   Common Genera Anabaena Aphanizomenon Oscillatoria Microcystis Chroococus

Cyanobacteria Blooms in Lake Erie  Microcystis sp. Blooms form in June-Sept Blooms form in June-Sept Produces Microcystin toxin Produces Microcystin toxin Disrupt recreational use of lake Disrupt recreational use of lake Algae washes ashore and decays Algae washes ashore and decays City of Toledo spends $4K/ day to remove Microcystis from drinking water supply City of Toledo spends $4K/ day to remove Microcystis from drinking water supply  Lyngbya wollei Recent problem in Lake Erie (2006) Recent problem in Lake Erie (2006) Grows on bottom in shallow waters Grows on bottom in shallow waters May Produce PSTs May Produce PSTs Mats float to surface and wash ashore Mats float to surface and wash ashore Severe disruption of shoreline, nuisance to property owners and beach users Severe disruption of shoreline, nuisance to property 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 phytoplankton species (1/2 of them are green algae) Most similar to higher plants Green Algae (Chlorophyta)

  Examples Volvox sp. colonial Flagellated cells in mucilage matrix Daughter colonies within parent colony Green Algae (Chlorophyta)

Colonies in black dye to highlight mucilage matrix