8 The Water Column Plankton. Notes for Marine Biology: Function, Biodiversity, Ecology by Jeffrey S. Levinton

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1 8 The Water Column Plankton Notes for Marine Biology: Function, Biodiversity, Ecology by Jeffrey S. Levinton

2 Plankton: Definitions Plankton: organisms living in the water column, too small to be able to swim counter to typical ocean currents (Nekton?) Phytoplankton Zooplankton Mixoplankton (zooplankton that contain chloroplasts derived from phytoplankton food) Holoplankton vs Meroplankton

3 Plankton: Definitions 4 Size classes

4 Vertical Position of Plankton - Factors Flotation, gas secretion Portuguese Man of War Bulk density - regulated by ionic substitution (Pyrocystis noctiluca : S0 4, Ca and Mg at half concentrations, substituted by NaCl to lower density; gas secretion and release (cuttlefish, Nautilus) Swimming behavior Turbulence stirs plankton through the water column

5 Chambered Nautilus

6 Vertical Position of Plankton - Factors Size of plankton - smaller plankton - low Reynolds number Low Re means there is a boundary layer around plankter s body Smaller organisms denser than seawater sink with a constant velocity, proportional to organismal volume, although increases of spines etc. can slow sinking

7 Thalassiosira sp. Chaetoceros sp. Asterionella japonica Diatoms

8 Diatoms lovely silica skeleton

9 Diatoms Phytoplankton Occur singly or form chains Denser than seawater and do not swim Size range of nanno to microplankton Encased in silica shell consisting of two valves Usually radially symmetrical Reproduce asexually by binary fission (size reduction) Also sexual reproduction Doubling once or twice per day usually

10 Diatoms pillbox-shaped shell of silica

11 Toxic diatom Pseudo-nitzschia sp. Domoic acid Sooty shearwater Puffinus griseus

12 Peridinium

13 Dinoflagellates Phytoplankton Secrete organic test and have two flagellae can swim Size range of nanno and microplankton Asexual and sexual reproduction Often several life history stages, benthic cysts Many species are heterotrophic Often abundant in tropics, mid-latitudes in summer A few species are the cause of red tides Alexandrium saxitoxin, Karenia brevis - brevitoxin

14 Other Groups Phytoplankton Cyanobacteria ( blue-green ) abundant, picoplankton (1 µm) nitrogen fixation very abundant in tropical ocean Coccolithophores - unicellular, nanoplanktonmicroplankton (10-20 µm), spherical and covered with calcium carbonate plates - coccoliths Silicoflagellates - unicellular, biflagellate, internal skeleton of silica scales, often in Antarctic, open ocean

15 Cyanobacteria

16 Synechococcus filamentous Cyanobacteria types

17 Coccolithophore Viruses!! Bloom of coccolithophores, near Newfoundland

18 Silicoflagellate

19 Other Groups Phytoplankton Numerous other groups, including many flagellated types, and species that cause major blooms, e.g. Aureococcus anophagefferens = brown tide, succeeds on organic nitrogen, low inorganic N CRUCIAL POINTS: DIVERSITY - DIFFERENT NUTRIENT NEEDS OF VARIOUS GROUPS (e.g., Fe, Si, Ca, P,N, heterotrophy) DIFFERENT PROPERTIES SUCH AS BULK DENSITY, ABILITY TO SWIM

20 Zooplankton Crustacean zooplankton (Arthropods) external chitin skeleton segmentation Paired jointed appendages (e.g., legs, antennae) antennae, mandibles and maxillae as head appendages Have simple-naupliar or in some cases compound eyes Include copepods, krill, amphipods (crabs, lobsters)

21 Copepods Zooplankton Females of different species with eggs

22 Zooplankton Crustaceans - Copepods Largest group of crustaceans in zooplankton Range from <1 - a few mm long - microplankton Planktonic copepods = Calanoida Long pair of antennae Swim mainly with aid of 5 pairs of thoracic appendages Lack compound eyes, medial naupliar eye Feed on phytoplankton or smaller zooplankton, depending on the species

23 maxilliped

24 Zooplankton Copepod Feeding Low Reynolds number - viscosity dominates Feeding current (blue) generated by thoracic appendages Maxilliped reaches out and grabs particles entrained in current

25 Metridia lucens capturing prey at low Re

26 Euphausiacea Euphausid krill Euphausia superba

Zooplankton Crustaceans - Euphausids (Krill) Shrimplike, up to 5 cm long Abundant in Antarctic and in upwelling regions Main food of baleen whales in Antarctic Feed on

27 Zooplankton Crustaceans - Euphausids (Krill) Shrimplike, up to 5 cm long Abundant in Antarctic and in upwelling regions Main food of baleen whales in Antarctic Feed on phytoplankton and smaller zooplankton Feeding by means of group of appendages that form a basket - appendages have setae and smaller setules, hairs that capture particles

28 Zooplankton Gelatinous Zooplankton Jellies include a wide variety of distantly related groups, all have gelatinous material used for support (hydrostatic skeleton)

29 Zooplankton Gelatinous Zooplankton - Cnidaria Planktonic Cnidaria Scyphozoan jellyfish, and siphonophores, specialized colonial and polymorphic cnidarians such as Portuguese man-of-war mainly carnivores, use nematocysts stinging or sticky or grabbing cells - on tentacles Also Hydrozoan jellyfish (some meroplanktonic jellyfish stages)

30 Zooplankton Cnidaria - Scyphozoan jellyfish Note muscular bell and tentacles

31 Zooplankton Cnidaria Siphonophores - colonial Porpita (ca. 10 cm wide) Physophora (50 mm high) Siphonophores By-the-wind-sailor Velella

32 Physalia physalis Portuguese Man of War

33 Assignment for Wednesday Read chapter 10 Hot Topics 10.1 p Chapter 9: pp (fishes)

34 More information: Google Stony Brook And Living World More information: Google Stony Brook And Living World

35 Zooplankton Gelatinous Zooplankton Ctenophores = Comb jellies Microcarnivores - feed on smaller zooplankton, planktonic eggs, invertebrate larvae 8 rows of meridional plates, some have two long tentacles Flashing light! Meridional plates refract light (Newton rings) also bioluminescence (luciferinluciferase system)

36 Zooplankton Gelatinous Zooplankton - Ctenophores

37 Zooplankton Gelatinous Zooplankton - Salps Related to benthic sea squirts, but have incurrent and exit siphons on opposite ends of body Solitary or colonial (up to 2 m in length) Gelatinous Zooplankton - Larvacea Have a tail, resemble tunicate swimming larvae Small, only a few mm long Tail generates current through house, current is strained by fine fibers that trap food in mucus mesh

38 Colonial Salp Pegea sp.

39 Larvacean Oikopleura

40 Zooplankton Arrow worms - Chaetognatha Torpedo shaped, a few cm in length Rapid swimmers, carnivorous Spadella cephaloptera

41 Zooplankton Pteropoda-sea butterflies Holoplanktonic snails (in danger, acidification because of aragonite shell) Swim by means of lateral projections from foot Suspension feed or are carnivorous, depending upon species

42 Zooplankton Planktonic polychaetes Have very well developed parapodia

43 Foraminifera Radiolaria Ciliata Zooplankton Protistan zooplankton groups

44 Zooplankton Protistan zooplankton - Foraminifera Secrete skeleton -chambers of calcium carbonate, sometimes with great ornamentation Common in plankton Size ~ 1 mm to a few mm Contractile pseudopodia trap food particles Foram ooze - deep-sea sediment

Zooplankton Protistan zooplankton - Radiolaria skeleton

singly and as colonies, depending on species Common in

interior cell from exterior cytoplasm, which streams out

45 Zooplankton Protistan zooplankton - Radiolaria skeleton of silica, sometimes with great ornamentation, occurs singly and as colonies, depending on species Common in plankton Size ~ 50 μm to a few mm A membrane separates interior cell from exterior cytoplasm, which streams out something like foraminifera Radiolarian ooze - deeper than foram ooze

size from about 50 μm to over 1 mm in length, covered with rows of cilia

46 Zooplankton Protistan zooplankton - Ciliates Common in plankton, feed on bacteria, smaller phytoplankton, some mixotrophic Elongate, ranging from size from about 50 μm to over 1 mm in length, covered with rows of cilia Strombidium, 80 μm long Strombidium sp. under UV light, ingested chloroplasts in red

47 Phytoplankton Groups Summary Diatoms important component of phytoplankton blooms in mid and hi latitudes, Si, not mobile, sink, short gen time, some toxic groups. Dinoflagellates organic skeleton, two flagellae, mobile, important in phytoplankton blooms world wide, some are very toxic to animals (Manatees) Cyanobacteria blue-green bacteria - photosynthetic, nitrogen fixation, spherical cells or thread like colonies Coccolithophores major blooms, calcium carbonate plates make a sphere, Silicoflagellates require silicon, like diatoms Numerous other groups

48 Zooplankton groups summary Crustacea mainly copepods and krill Gelatinous zooplankton Cnidaria (Jellyfish, Siphonophores); Ctenophores, Salps, Larvacea Arrow worms, Pteropods, Planktonic polychaetes Protistans foraminiferans, radiolarians

49 The End

ZOOPLANKTON. Zooplankton: 2. Crustaceans Copepods. Diverse -- protozoans and others

ZOOPLANKTON. Zooplankton: 2. Crustaceans Copepods. Diverse -- protozoans and others ZOOPLANKTON Diverse -- protozoans and others Nutrition modes: Herbivores (graze on phytoplankton) Carnivores (predators) Radiolaria Foraminifera Zooplankton: 1. Protozoans: Foraminifera and Radiolarians