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PLANKTON. HIGH SEAS DRIFTERS. PLANKTON SIZE. ULTRA PLANKTON : less than 0.005 mm across. NANNO PLANKTON : 0.005 - 0.07 mm. MICRO PLANKTON : 0.07 – 1 mm. Also called net plankton as they’re often collected in plankton net samples. But plankton can be extremely large….
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PLANKTON HIGH SEAS DRIFTERS
PLANKTON SIZE ULTRA PLANKTON : less than 0.005 mm across NANNO PLANKTON : 0.005 - 0.07 mm MICRO PLANKTON : 0.07 – 1 mm Also called net plankton as they’re often collected in plankton net samples But plankton can be extremely large…
PHYTOPLANKTON Phytoplankton is self-feeding or AUTOTROPIC constructing sugars etc via photosynthesis Phytoplankton can be found as single cells or long chains or FILAMENTS The majority of phytoplankton is MICRO ALGAE Although there are planktonic sea weeds = MACRO ALGAE e.g. Sargassum spp.
TYPES OF PHYTOPLANKTON GOLDEN ALGAE (Phylum Chrysophyta) Contain a yellow-golden pigment CAROTIN Two main groups: DIATOMS COCCOLITHOPHORES
DIATOMS Algae that are contained in a cell wall or FRUSTULE made of PECTIN (a jelly like substance) The frustule contains a a weblike structure (a microscopic shell)or TEST The tests are made of silica (SiO2.nH2O) When they die they form a SILICACEOUS OOZE or DIATOMACEUS EARTH Diatoms are the most productive group of marine algae
Diatoms can have radial or bilateral (two sided) symmetry
DIATOM REPRODUCTION The two halves of a diatom’s frustule fit together -like a pill box When the diatom grows to a certain size the halves of the frustule separate Each daughter cell grows a new frustule half In high sunlight & nutrient conditions diatoms can reproduce every 12 – 24 hours When so many have reproduced the sea water becomes discolored = ALGAL BLOOM
Spines can reduce the rate at which diatoms sink (increasing friction - like parachutes) Some also contain droplets of oil that make them less dense (& buoyant)
COCCOLITHOPHORES These are usually Nanno plankton or smaller (and don’t get caught in plankton nets) They are covered in circular plates These plates are made of calcium carbonate (CaCO3) When they die they form a calcareous sediment – e.g. CALCAREOUS OOZE
DINOFLAGELLATES DINOFLAGELLATES (Phylum Pyrrophyta) Have two whip-like FLAGELLA These lash back and forth within grooves or the organisms’ surface - spinning the dinoflagellates The tests or coatings of dinoflagellates are made of the carbohydrate CELLULOSE These decompose quickly and easily so their remains do not form sediments
DINOFLAGELLATES They contain red or green pigments RED TIDES = blooms of red dinoflagellates They can be AUTOTROPHIC and HETEROTROPHIC (feed on other organisms) This means that they can supplement and sustain themselves in lower light conditions that other algae They are the second most productive group of phytoplankton
OTHER PHYTOPLANKTON Green algae Silicoflagellates Chrysomonads Cryptomonads Cyanobacteria (or blue green algae)
BACTERIA There are an estimated 100,000,000,000,000,000,000,000,000,000 bacteria in the marine environment One third occur in the upper ocean (planktonic) and two-thirds in deep water (mostly benthic) CYANOBACTERIA (or blue green algae) photosynthesize and are a component of phytoplankton They are an important food source for protozoan zooplankton Also important in decomposing dead marine organisms
ZOOPLANKTON = planktonic animals Either herbivores (feeding on phytoplankton) Or carnivores (feeding on other zooplankton) Although most zooplankton have the ability to swim, this motion is usually short-distance to avoid predators or vertical movement Some species move daily from depth to surface waters– maintaining light levels or following prey BUT they rely on currents for large scale movement (drifting) hence planktonic
ZOOPLANKTON The most common members of the zooplankton = CRUSTACEANS (Phylum Arthropoda; Class Crustacea) Especially COPEOPODS (e.g. Calanus or Oithona) or the larger EUPHAUSIIDS (shrimp-like crustaceans) Both are herbivores (1ary CONSUMERS) (although euphausiids can be carnivores as well- 2ary CONSUMERS) The dominant euphausiids in the polar regions = KRILL (e.g. Euphausia superba)
FORMINIFERNS & RADIOLARIANS Amoeba-like protozoans (Phylum Sarcodina) Forminiferans are are covered with a calcareous (CaCO3) shell Radiolarians are covered in a silicaceous test covered with spines Both are live in warmer waters and feed on diatoms and small protozoa Their shells and tests form oozes after death
RADIOLARIANS TINTINNID A bell-shaped protozoan that is propelled by hair-like CILIA FORMINIFERAN
Undulations of their wing-like muscular foot help them to swim (x 2) PTEROPODS Phylum Mollusca – related to snails May or may not have a calcareous shell
CTENOPHORES (comb-jellies) Bands of cilia help to propel these translucent carnivores TUNICATES (sea squirts) Filter feeders Usually tunicates are sessile benthic creatures - but can be free swimming
Phylum COELENTERATA or CNIDARIA = jellyfish
Some jellyfish spend their entire lives as carnivorous/herbivorous plankton Others spend part of their lives as plankton before settling down to become sessile and benthic (like sea anemones) Some exist as colonial organisms (a collection of individual organisms working together) e.g. the Portugese man-o-war (Physalia)
Plankton that spend their entire lives as plankton = HOLOPLANKTON Organisms that only spend part of their life cycle as plankton = MEROPLANKTON
Meroplankton tend to be larval forms of other marine species
WHEN PLANKTON GOES BAD ! In previous lectures the problems of nutrient pollution and algal blooms have been discussed Algal blooms can use up dissolved oxygen when respiring making waters ANOXIC In addition they can produce toxins that poison marine life = HABs or HARMFUL ALGAL BLOOMS One of the most infamous types of HABs = RED TIDES
WHEN PLANKTON GOES BAD ! 6% of phytoplankton species can cause HABs The toxins are produced to protect the phytoplankton from predators Humans can be effected by these toxins if eating seafood that has been contaminated Especially shellfish (in which the toxins bio-accumulate) The economic impacts of HABs in the US = $40 million a year