1. Ocean plants Maia McGuire Florida Sea Grant Extension Agent

2. Terminology • Aquatic • Estuarine • Freshwater • Marine • Emergent • Floating • Submerged • Phytoplankton • Algae • Seagrass • SAV (submerged aquatic vegetation) • True plant

3. 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

4. Activity • Design and construct a plankter

5. 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

6. 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

7. 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 (?)

8. 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

9. Reproduction in algae • Sexual reproduction involves production of spores, which produce a gametophyte, which produces gametes

10. Green algae • Contain chlorophyll a and b • Examples: sea lettuce (Ulvalactuca), dead man’s fingers (Codium fragile)

11. Some make calcium carbonate skeletons

12. Brown algae • Contain chlorophyll a and c • Includes Sargassum seaweed

13. Red algae • Contain chlorophyll a • Source of agar, carrageenan (used in many food products • Few have common names • Often finely branching

14. Calcareous red algae • Often found on coral reefs—help “cement” the reef surface

15. Activity • Pressing seaweed

16. 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)

17. http://fmel.ifas.ufl.edu/habitat/seagrass_parts.shtml

18. Thalassia testudinumTurtle 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

19. Halodule wrightiiShoal 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

20. Syringodium filiformeManatee 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

21. Halophilaengelmanni, H. decipiens, H. johnsonii • Relatively sparsely distributed • Paddle-shaped leaf blades • Johnson’s seagrass is listed as a threatened species

22. Ruppia maritimaWidgeon grass • Often found alongside Halodule in areas of lower salinity • Important food for waterfowl • Primarily a freshwater plant

23. Seagrass distribution Thalassia testudinum Halodule wrightii Syringodium filiforme Halophila decipiens Halophila johnsonii Halophila engelmanii

24. Ruppia maritima distribution

25. 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)

26. 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

27. Productivity • Highly productive ecosystems • Important food source, for grazers and as detritus

28. Seagrasses provide habitat • Many species of fish • Molluscs (e.g. scallops, snails) • Shrimp, crabs and other crustaceans • Worms

29. Threats to seagrasses • Physical damage • Dredging, prop scars/blowouts • Eutrophication • Salinity stress • Temperature stress

30. Mangroves • Emergent plants • Very salt-tolerant • Have adaptations to deal with salt and wave action • Occur in zones • Three species in Florida

31. Red mangrove • Rhizophora mangle • Has prop roots to stabilize tree

33. Black mangrove • Avicenniagerminans • Has “pneumatophores” (breathing roots) • Salty leaves

35. White mangrove • Lagunculariaracemosa

36. 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