life in the pelagic: an introduction to the...
TRANSCRIPT
Size classifications and terminology
• Classification of planktonic organisms is generally based upon size – rather than function (most methods involve filtration which distinguishes organisms based upon size rather than species).
• This can be problematic because in the plankton, trophic position is not always determined by size (size ratios between predator and prey are not constant).
Abundance of living organisms
6x106 in Washington StateHumans (2m)
Typical abundanceOrganism and size
10 to 104 per mlPhytoplankton (20-200um)
10 to 102 per mlProtizoan plankton (20-50um)
102 to 104 per mlNanoflagellates (1-10um)
105 to 107 per mlBacterioplankton (~1um)
Bacterioplankton in Aquatic Systems
• Found in all natural waters
• Non-pathogenic!
• Small (≤1µm) yet abundant (>106 cells ml-1)
• Comparable in biomass to phytoplankton
• Fundamental in nutrient & carbon cycling
• Drive water quality parameters (i.e. anoxia, nutrient
availability)
• Extremely diverse
(DAPI stained slide of bacterioplankton from Chesapeake Bay)10 µm
•Diverse and ubiquitous viral community in the marine environment
•Significant role suspected (certainly impact bacteria and may also impact primary production and higher trophic levels, viruses suspected in some marine mammal beachings).
•Viruses may be important agents in demise of some phytoplankton blooms (e.g., Trichodesmium)
•Viruses are important agents for DOM release and nutrient cycling
0.1um
Bacteriophage
Femtoplankton (0.02 – 0.2 µm)
Bacteria•Very important role in marine food webs, especially degradation and recycling
•Ubiquitous in ocean (~106 / ml)•Various forms (motile, rods, spiral, coccoid)
Archaea•Distinct RNA•Early evolutionary separation•Favoring extreme environments•Recently discovered in ocean
Picoplankton (0.2 – 2 µm)
Vertical distribution of Bacteria and Archaea cell abundance at HOTS (Karner et al 2001).• Opposite patterns of distribution• Archaea are ubiquitous, but biogeochemical significance is poorly understood
Picoplankton (0.2 – 2 µm)
Cyanobacteria – “blue-green algae”
Photosynthetic bacteriae.g. Synechococcus spp. • Up to 106/ml in euphotic zone• In both coastal and oceanic waters• In temperate and tropical oceans• Can play major role in primary production, especially open ocean
Prochlorophytes
•Prochlorococcus marinus•Abundant at base of the euphotic zone in open ocean (106 / ml)•Ubiquitous distribution•Can play a major role in primary production, especially in the open ocean•Different strains have been identified that live in different depths in the water column and have different metabolic capabilities particularly with respect to what forms of nutrients they can use, i.e., NH4 vs. NO3.
Note: Prochlorococcus is currently believed to be the most abundant form of plant life on earth.
2µm
More on Picoplankton (0.2 – 2 µm)
Mostly small eukaryotic phytoplankton
Dominate more oligotrophic open ocean environments
small pennate diatom
small centric diatomdinoflagellates
coccolithophorid
Nanoplankton (2 – 20 µm)
Large eukaryotic phytoplankton
Prominent in productive coastal / upwelling zones
centric diatom
chain-forming diatoms
large dinoflagellates
Microphytoplankton (20 – 200 µm)
Heterosigma
These are heterotrophic and mixotrophic protozoans
•Large group and taxonomically diverse• ciliates• dinoflagellates• heterotrophic nanoflagellates (HNFs)• radiolarians (silica) and foraminifera (calcite)
•Same size as the microphytoplankton (2 – 200 µm)
•Heterotrophic and mixotrophic forms
•Very important consumers in marine environments!!!
Microzooplankton (2 – 200 µm)
Tintinnid ciliate
Oxyrrhis marina
Leegaardiella sp.
Laboea strobila
http://www.aslo.org/photopost
Ciliates
Favella-like tintinnid
Favella-like tintinnid
Eutintinnis
Mesozooplankton (200 um – 2 mm)
• Relatively large, planktonic heterotrophs (200 µm – 2 mm)• Huge, diverse group…
• Larger protozoans• Coelenterates• Cheatognaths• Annelids• Molluscs• Arthropods• Copepods• Amphipods• Euphausiids• Small larvaceans and salps• Pteropods and heteropods
Meroplankton•As opposed to holoplankton or true plankton•Eggs, larvae and juvenile stages of benthic invertebrates and fish•Time spent in the plankton may be minutes to months•Especially important in coastal and estuarine waters as you will see on the zooplankton lab
Barnacle nauplius
Polycheate larvae
Crab zoea
Crab megalopaBarnacle cypris
Sea urchinlarvae
Snail veliger
Starfish larvae
Macroplankton (2-20 cm) and Megaplankton (20-200 cm)
• “Jellyfish” are prominent examples• Most are classified as plankton• Hydrozoan, Scyphozoan and Cubozoan medusae• Ctenophores• Salps• Larvaceans• Pteropods and Heteropods
Scyphozoan medusa (Chrysaora)(megaplankton)
Ctenophores like Mnemiopsis and Beroe(macroplankton)
Major Phytoplankton Groups
1) Diatoms (20um to 2mm)• Most abundant, rapidly dividing organisms, bloomers• Silicate frustrule (shell) – pennates (motile) and centrics• Solitary and chain forming
2) Dinoflagellates (20 – 40um)• Motile with flagella• Auto, mixo, hetero-trophic• HABs (paralytic shellfish poisoning, Gymnodinium, red tides
(Prorocentrum), Pfiesteria piscicida, zooxanthellae• Noctiluca sp. (bioluminescence)
3) Microflagellates (2-30um) • Coccolithophores, primnesiophytes, cryptophytes
4) Picophytoplankton (<2um)• Prochlorococcus and Synechococcus
Other phytoflagellates
cryptomonadsChrysochromulina
bergeriEmiliania huxleyi
Pyramimonas
Phaeocystisglobosa