Biota of Aquatic Environemnts
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Transcript Biota of Aquatic Environemnts
Phytoplankton
• Photosynthetic autotrophs (algae) drifting
passively in aquatic environments
– Nanoplankton 2-20 um
– Net plankton 20-200 um
Some common phyla:
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Euglenophyta (euglenoids)
Pyrrhophyta (dinoflagellates)
Bacillariophyta (diatoms)
Chlorophyta (green algae)
Scenedesmus
Where are algae found?
On the bottom (benthic or “epipelic” algae)
Attached to aquatic macrophytes (periphyton)
Good access to nutrients in sediments, but can only be
in shallow water due to light limitation
epilithic - rock
epipsammic - sand
Algae and animals form a community (the Aufwuchs) in
the “slime” on stems of aquatic plants
In the water column (phytoplankton)
Phytoplankton
• Pigments
– Often used to categorize phytoplankton
– All photosynthetic algae possess photosynthetic
pigments.
• Chlorophylls - Chla in all algae; also b and c (absorb blue, red)
• Carotenoids - carotenes, xanthophylls (absorb blue, green)
• Phycobilins - pigment – bonded to proteins (absorb green,
yellow, orange, red)
– Similar pigments usually indicates evolutionary
relationships
• Special adaptations
– Flagellae
• motility (slight)
Green Algae
Chlamydomonas
Absorption spectra for different algal pigments
Plankton sampling techniques
Plankton net
Water
sampler
Plankton counting techniques
Sedgewick-Rafter
Counting Cells
Palmer
Counting Cells
The number of species recorded from the
same water body depends on….
• Sampling method (net or water samples)
• Number and location of sampling stations
(littoral vs. pelagic; presence of floating
macrophytes, etc.)
• Time span of the investigation
• Time of the year (and time of the day)
Phytoplankton communities in the tropics
• Lack of comprehensive data on
phytoplankton communities in the tropics
(most citations deal with reef algae, toxins and control of algae in aquaria).
• Even so, there seems no trend towards
increased algal diversity towards the
equator (applies to lakes, rivers, wetlands
and reservoirs).
Euglenophyta
Euglena
Phacus
Dinoflagellates (Pyrrhophyta)
Ceratium
Red Tide: A bloom of dinoflagellates
Diatoms (Bacillariophyta)
Cyclotella
Navicula
Diatoms (Bacillariophyta)
Centric Diatoms
microbes.limnology.wisc.edu/outreach/images
protist.i.hosei.ac.jp/pdb/Images/Heterokont
ophyta/Centrales/Cyclotella/Cyclotella.jpg
Pennate Diatoms
dr-ralf-wagner.de/Bilder/Surirella
plantphys.info/organismal/lechtml/images/navicula.jpg
www.ansp.org/research/pcer/images/Eucocconeis
Diatom shell
Single celled, colonial and multicellular chlorophytes
Volvox
Pediastrum
Caulerpa
Periphyton growing along rocks in mesotrophic Lake Titicaca, Peru)
N is more frequently limiting to freshwater production in
tropical lakes and rivers.
Source: Downing et al. 1998
• N may be lost from aquatic systems more rapidly
in the tropics than the temperate zone (e.g. through denitrification)
• P erosion from tropical landscapes and P mobilization
in aquatic environments may be more rapid.
Species: Caulerpa taxifolia
Division: Chlorophyta; Class:Ulvophyceae
Native range: Hawaii, Brazil, SE Asia (i.e., tropical).
Now: Worldwide distribution with large outbreaks after accidental introduction
in the Mediterranean, Southern California and Australia.
Successful invader because: (1) rapid reproduction/spread with fragmentation, (2)
lack of natural grazers, (3) rapid growth, and (4) toxic to herbivores
Lewis, 1990
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0.45
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