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Plankton Summary

Plankton Summary. Plankton can’t control their location and are moved about by wind, waves, currents and tides. Plankton are usually grouped by size, ranging from femtoplankton to megaplankton

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Plankton Summary

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  1. Plankton Summary • Plankton can’t control their location and are moved about by wind, waves, currents and tides. Plankton are usually grouped by size, ranging from femtoplankton to megaplankton • Diatoms are dominant phytoplankton in estuaries while dinoflagellates (some of which are harmful) and coccolithophores dominate surface waters offshore (i.e., nanoplankton are most abundant inshore and picoplankton most abundant offshore) • Prochlorophytes are tiny, extremely abundant picoplankters that occur near the base of the sunlit layer in offshore waters • Cyanobacteria (e.g., Trichodesmium) are nitrogen fixers and can be limited by iron

  2. Plankton Summary • Half of all primary production occurs in shallow waters of the continental shelf, while the other half is distributed over the rest of the entire ocean. • Net primary production equals gross primary production (total production) minus respiration, which is the amount available for consumption by herbivores • The euphotic zone is the depth to which light penetrates and photosynthesis can occur • Four methods of measuring primary production are: oxygen evolution, 14C uptake, satellite sensing, and fluorometry • Predation can cause: changes in size distribution; both decreases and increases in diversity; morphological modifications (spines, mimicry, crypsis)

  3. Plankton Summary • Light and nutrients are major factors controlling primary production (p.p.). Light inhibition occurs when there is too much light, and for this reason the max p.p. occurs below the surface • Compensation depth is the depth where for a given algal cell, photosynthesis = respiration • Ocean water has much less nitrogen than soil, which is why N is often limiting in the ocean • Thermoclines prevent mixing of surface and bottom waters and prevents nutrients from re-entering surface waters • High nutrient low chlorophyll (HNLC) zones are limited by iron

  4. Plankton Summary • Critical Depth is the point at which Gross Photosynthesis = Total Plant Respiration, and is a characteristic of the population • Zooplankton regenerate nutrients by sloppy feeding and excretion, and can control phytoplankton abundance. The polar, temperate and tropical regions have characteristic seasonal patterns of phytoplankton and zooplankton abundance • Bacterial cells are 5 orders of magnitude more abundant than algal cells and have been high growth rates. They use DOC as an energy source and can outcompete phytoplankton for nutrients. • Original microbial loop concerned DOC, bacteria, flagellates and ciliates. The microbial web also includes the small phytoplankton that cannot be consumed by large zooplankton

  5. Plankton Summary • Viruses are an order of magnitude more abundant than bacteria, and cause them significant mortality. Virus also transmit genetic material to their hosts and can be imporant agents of evolutionary change for them. • When bacterial consumption of DOC exceeds primary production this is NET HETEROTRPHY. When production exceeds bacterial consumption this is NET AUTOTROPHY

  6. Zooplankton http://www.microscopy-uk.org.uk

  7. Planktos: “drifts” in greek Their distribution depends on currents and gyres Certain zooplankton can swim well, but distribution controlled by current patterns Zooplankton: all heterotrophic plankton except bacteria and viruses; size range from 2 µm (heterotrophic flagellates, protists) up to several meters (jellyfish)

  8. Herbivorous zooplankton: Grazers

  9. Nutritional modes in zooplankton Herbivores: feed primarily on phytoplankton Carnivores: feed primarily on other zooplankton (animals) Detrivores: feed primarily on dead organic matter (detritus)  Omnivores: feed on mixed diet of plants and animals and detritus

  10. Feeding modes in Zooplankton Filter feeders Predators – catch individual particles

  11. Filter Feeder Copepod

  12. Filter Feeder Ctenophore

  13. Predator Chaetognath Arrow Worm

  14. Life cycles in Zooplankton Holoplankton: spend entire life in the water column (pelagic) Meroplankton: spend only part of their life in the pelagic environment, mostly larval forms of invertebrates and fish

  15. Holoplankton Copepods Planktonic crustaceans

  16. Meroplankton Nauplius larva http://www.microscopy-uk.org.uk

  17. Meroplankton Cypris larva http://www.microscopy-uk.org.uk

  18. http://science.whoi.edu/labs/pinedalab/

  19. Cypris larva and metamorphosed juveniles http://science.whoi.edu/labs/pinedalab/

  20. Barnacle population regulation http://science.whoi.edu/labs/pinedalab/

  21. Ichthyoplankton Gadidae Gadus morhua

  22. Gadidae Gadus morhua Ichthyoplankton

  23. Gadidae Atlantic cod Gadus morhua Demersal Adult

  24. Protists: Protozooplankton Dinoflagellates: heterotrophic relatives to the phototrophic Dinophyceae; naked and thecate forms. Noctiluca miliaris – up to 1 mm or bigger, bioluminescence, prey on fish egg & zooplankton Zooflagellates: heterotrophic nanoflagellates (HNF): taxonomically mixed group of small, naked flagellates, feed on bacteria and small phytoplankton; choanoflagellates: collar around flagella Foraminifera: relatives of amoeba with calcareous shell, which is composed of a series of chambers; contribute to ooze sediments; 30 µm to 1-2 mm, bacteriovores; most abundant 40°N – 40°S

  25. Dinoflagellates Noctiluca miliaris

  26. Colonial choanoflagellates Bacteriofages (Ross Sea) http://www.nsf.gov/pubs/1999/nsf98106/98106htm/ht-015.gif

  27. Foraminifera (calcareous – all latitudes)

  28. Radiolaria:spherical, amoeboid cells with silica capsule; 50 µm to several mm; contribute to silica ooze sediments, feed on bacteria, small phyto- and zooplankton; cold water and deep-sea Ciliates:feed on bacteria, phytoplankton, HNF; naked forms more abundant but hard to study (delicate!); tintinnids: sub-group of ciliates with vase-like external shell made of protein; herbivores Protists: Protozooplankton

  29. Figure 3.21b Radiolarians (siliceous – low latitudes)

  30. http://www.jochemnet.de/fiu/

  31. Live Radiolarian http://www-odp.tamu.edu/public/life/199/radiolaria.jpg

  32. Cnidaria: primitive metazoans; some holoplanktonic, others have benthic stages; carnivorous (crustaceans, fish); long tentacles carry nematocysts used to inject venoms into prey; Medusae: single organisms, few mm to several meters Siphonophores: colonies of animals with specialization: feeding polyps, reproductive polyps, swimming polyps; Physalia physalis (Portuguese man-of-war), common in tropical waters, Gulf of Mexico, drifted by the wind and belong to the pleuston (live on top of water surface) Invertebrate Holoplankton

  33. Cnidarian (medusae)

  34. Cnidaria (medusae)

  35. Cnidaria (siphonophora)

  36. Ctenophores:separate phylum (not Cnidarians; transparent organisms, swim with fused cilia; no nematocysts; prey on zooplankton, fish eggs, sometimes small fish; important to fisheries due to grazing on fish eggs and competition for fish food Chaetognaths: arrow worms, carnivorous, <4 cm Polychaets: Tomopteris spp. only important planktonic genus Invertebrate Holoplankton

  37. Ctenophora (comb jellies)

  38. Ctenophora (comb jellies)

  39. Invertebrate Holoplankton Mollusca:  Heteropods: small group of pelagic relatives of snails, snail foot developed into a single “fin”; good eyes, visual predators Pteropods: snail foot developed into paired “wings”; suspension feeder – produce large mucous nets to capture prey; carbonate shells produce pteropod ooze on sea floor

  40. Heteropod (Preys on Ctenophores)

  41. Pteropod • http://www.mbari.org/expeditions/

  42. Protochordate Holoplankton Appendicularia: group of Chordata, live in gelatinous balloons (house) that are periodically abandoned; empty houses provide valuable carbon source for bacteria and help to form marine snow; filter feeders of nanoplankton Salps or Tunicates:group of Chordata, mostly warm water; typically barrel-form, filter feeders; occur in swarms, which can wipe the water clean of nanoplankton; large fecal bands, transport of nano- and picoplankton to deep-sea; single or colonies

  43. Appendicularian

  44. Pelagic Salps

  45. Arthropoda: crustacean zooplankton Cladocera (water fleas): six marine species (Podon spp., Evadne spp.), one brackish water species in the Baltic Sea; fast reproduction by parthenogenesis (without males and egg fertilization) and pedogenesis (young embryos initiate parthenogenetic reproduction before hatching) Amphipoda: less abundant in pelagic environment, common genus Themisto; frequently found on siphonophores, medusae, ctenophores, salps Euphausiida: krill; 15-100 mm, pronounced vertical migration; not plankton sensu strictu; visual predators, fast swimmers, often undersampled because they escape plankton nets; important as prey for commercial fish (herring, mackerel, salmon, tuna) and whales (Antarctica)

  46. Amphipoda

  47. Amphipoda (parasites of gelatinous plankton)

  48. http://www.imagequest3d.com/catalogue/deepsea/images/l038_jpg.jpghttp://www.imagequest3d.com/catalogue/deepsea/images/l038_jpg.jpg

  49. Euphasids (krill)

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