Transcript Ocean plantsx

Ocean plants
Maia McGuire
Florida Sea Grant Extension Agent
Terminology
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Aquatic
Estuarine
Freshwater
Marine
Emergent
Floating
Submerged
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Phytoplankton
Algae
Seagrass
SAV (submerged
aquatic vegetation)
• True plant
Phytoplankton
• Mostly single-celled,
photosynthetic,
microscopic plants
• DIATOMS are the most
abundant type of
phytoplankton—they
have a silica “housing”
• DINOFLAGELLATES
often produce toxins
(and red tides!); some
bioluminesce
Activity
• Design and construct a plankter
Algae blooms
• Usually a response to increased nutrient levels
• Phytoplankton reproduce by dividing, creating
high concentrations (“blooms”)
• Nutrient loading can be natural (upwelling) or
related to runoff from land
Red tide
• Bloom of a type of dinoflagellate
• Algae release a chemical that goes into the
water and also into the air
– Causes respiratory difficulties to humans
– Toxic to fish and sometimes to marine mammals
Red tide (cont.)
• Blooms form offshore in
Gulf of Mexico
• Can bloom in any month
of the year
• Blooms can last for weeks
to months; may be
lengthened by runoff from
land (?)
Multi-cellular plants…
• Algae
– Not considered true plants—no roots, flowers,
vascular system
– Often called “seaweed”
– Often use holdfasts to attach to the substrate
– Different groups of algae contain different types of
chlorophyll
– Green algae, brown algae, red algae
Reproduction in algae
• Sexual reproduction involves production of
spores, which produce a gametophyte, which
produces gametes
Green algae
• Contain chlorophyll a and b
• Examples: sea lettuce (Ulva lactuca), dead
man’s fingers (Codium fragile)
Some make calcium carbonate
skeletons
Brown algae
• Contain chlorophyll a and c
• Includes Sargassum seaweed
Red algae
• Contain chlorophyll a
• Source of agar, carrageenan (used in many
food products
• Few have common names
• Often finely branching
Calcareous red algae
• Often found on coral reefs—help “cement”
the reef surface
Activity
• Pressing seaweed
Seagrasses
• Fully submerged marine plants; true
angiosperms
– True roots, vascular system, flowers
– Reproduce asexually using rhizomes
• 6-7 species; 3 common
– Turtle grass, Shoal grass, Manatee grass
– Star grass, Paddle grass, Johnson’s seagrass,
– Widgeon grass (freshwater grass with high
salinity tolerance)
http://fmel.ifas.ufl.edu/habitat/seagrass_parts.shtml
Thalassia testudinum
Turtle grass
• Largest and most robust of
Florida’s seagrasses
• Flat, wide (4-12 mm) leaf
blades (10-35 cm in length)
• 2-5 leaves per shoot
• Forms extensive meadows
Halodule wrightii
Shoal grass
• Early colonizer of disturbed areas
or areas too deep or shallow for
other seagrasses
– Tolerates wide range of T, S
• Leaves flat (1-3 mm wide), 10-20
cm long
• Tips of leaves have 2-3 points
Syringodium filiforme
Manatee grass
• Leaves are round (like
spaghetti); 1-1.5 mm in
diameter; length varies but
can reach 50 cm
• Commonly found mixed
with other seagrasses or in
small monospecific patches
Halophila engelmanni, H. decipiens, H.
johnsonii
• Relatively sparsely distributed
• Paddle-shaped leaf blades
• Johnson’s seagrass is listed as a threatened
species
Ruppia maritima
Widgeon grass
• Often found alongside
Halodule in areas of
lower salinity
• Important food for
waterfowl
• Primarily a freshwater
plant
Seagrass distribution
Thalassia
testudinum
Halophila
engelmanii
Halodule
wrightii
Syringodium
filiforme
Halophila
decipiens
Halophila
johnsonii
Ruppia maritima distribution
Seagrass biology
• Growth
– Thalassia blades can grow as much as 1 cm/day
– Growth is slowed by cooler temperatures
– Extremes in temperatures (hot or cold) can kill
leaf blades
– Optimal temperature range 20-30° C
– Optimal salinity range 24-35 ppt
– Extensive seagrass beds not found deeper than
10-15 m (light and pressure are both factors)
Zonation
• Halodule grows in shallowest water and has
highest tolerance to exposure
• Thalassia is most dominant; forms large
meadows in waters up to 10-12 m deep
• Syringodium forms meadows in deep water
(up to 15 m)
• Halodule and Halophila can grow in even
deeper water, but sparsely
Productivity
• Highly productive ecosystems
• Important food source, for grazers and as
detritus
Seagrasses provide habitat
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Many species of fish
Molluscs (e.g. scallops, snails)
Shrimp, crabs and other crustaceans
Worms
Threats to seagrasses
• Physical damage
– Dredging, prop scars/blowouts
• Eutrophication
• Salinity stress
• Temperature stress
Mangroves
• Emergent plants
• Very salt-tolerant
• Have adaptations to deal with salt and wave
action
• Occur in zones
• Three species in Florida
Red mangrove
• Rhizophora mangle
• Has prop roots to
stabilize tree
Black mangrove
• Avicennia germinans
• Has “pneumatophores”
(breathing roots)
• Salty leaves
White mangrove
• Laguncularia racemosa
Ocean stewardship
• Read “A new home for an old friend” to teach
kids that aquarium plants should not be
dumped into ponds or the ocean
• http://www.usc.edu/org/seagrant/caulerpa/index.html