What is SAV and Why Should I Care?

1. What is SAV and Why Should I Care?

2. SAV stands for Submerged Aquatic Vegetation • SAV is rooted vegetation that grows under water in shallow zones where light penetrates.

3. Chesapeake Bay Program SAV stands for Submerged Aquatic Vegetation • SAV is rooted vegetation that grows under water in shallow zones where light penetrates. • The various species of SAV are marine angiosperms (flowering plants).

4. John Melton SAV evolved from land plantsbut adapted to a totally underwater life • Special air-filled cells (lacunae) are present in the leaves and stems to provide the plants with buoyancy and support. • The leaves and stems lack the waxy cuticle that is characteristic of most terrestrial plants. This allows for easy exchange of gases and nutrients between the plants and surrounding water.

5. Bill Dennison SAV covers 10% of the world’s coastal oceans SAV in Australia (Seagrasses are SAV which can tolerate sea (salty) water.)

6. www.vims.edu We will focus on SAV in the Chesapeake Bay Location of the (year) 2000 SAV beds in Chesapeake Bay (Upper, Middle, and Lower zones), its tributaries, and the Delmarva Peninsula coastal bays

7. www.vims.edu We will focus on SAV in the Chesapeake Bay There are 16 species of SAV commonly found in the Chesapeake Bay or nearby rivers.

8. www.vims.edu We will focus on SAV in the Chesapeake Bay The Chesapeake Bay is our nation’s largest estuary … a partially enclosed body of water formed where freshwater from rivers flows into the ocean, mixing with the salty sea water.

9. www.chesapeakebay.net Salinity is a primary factor affecting SAV distribution • Wild celery grows in the upper bay. • The salinity there is 0-5 “psu”. • “psu” stands for “practical salinity units”, which are virtually identical to “parts per thousand”. • Tidal fresh-water species of SAV require a salinity of 0-0.5 psu. • Slightly brackish or “oligohaline” species of SAV require 0.5-5 psu.

10. www.chesapeakebay.net Salinity is a primary factor affecting SAV distribution • Redhead grass is a mid-bay species. • Mid-bay salinity is 5-18 psu. • Moderately brack- ish or “mesohaline” species of SAV require 5-18 psu.

11. www.chesapeakebay.net Salinity is a primary factor affecting SAV distribution • Eelgrass grows in the lower bay. • The salinity there is 18-35 psu. • High salinity or “polyhaline” species of SAV require 18-30 psu.

12. www.mbr-pwrc.usgs.gov www.dnr.state.md.us Later, we will focus on mid-bay or mesohaline species Photograph of redhead grass (Potamogeton perfoliatus) (Named for redhead duck, which likes to eat this grass.)

13. To grow, SAV needs sunlight

14. Bill Dennison To grow, SAV needs sunlight Below tide line to about 2 meters

15. Other habitat conditions influencing SAV distribution • Salinity • Light penetration • Water depth We’ve already mentioned: Can you think of some others? • Temperature • Nutrients • Water currents and wave action • Bottom sediment • More later …

16. Conceptual Diagram of Factors Influencing SAV Habitat

17. We have talked about the first part of this question … What is SAV and Why Should I Care? now let us talk about the second part.

18. www.chesapeakebay.net SAV plays an important role in the environment • Waterfowl SAV provides food and habitat for:

19. www.chesapeakebay.net www.chesapeakebay.net SAV plays an important role in the environment • Waterfowl • Finfish SAV provides food and habitat for:

20. www.chesapeakebay.net www.chesapeakebay.net www.vims.edu SAV plays an important role in the environment • Waterfowl • Finfish • Shellfish SAV provides food and habitat for:

21. www.chesapeakebay.net www.chesapeakebay.net www.chesapeakebay.net www.vims.edu SAV plays an important role in the environment • Waterfowl • Finfish • Shellfish • Invertebrates SAV provides food and habitat for:

22. David Harp David Harp David Harp David Harp SAV plays an important role in the environment SAV serves as nursery habitat and refuge from predators for many species of finfish and shellfish.

23. www.chesapeakebay.net SAV plays an important role in the environment SAV serves as nursery habitat and refuge from predators for many species of finfish and shellfish. Thus SAV indirectly supports various coastal fisheries.

24. noaa.chesapeakebay.net David Harp SAV plays an important role in the environment Studies have shown that densities of juvenile blue crabs can be as much as 30 times greater in SAV beds than in unvegetated areas.

25. www.vims.edu www.chesapeakebay.net SAV plays an important role in the environment In addition, blue crabs hide in Bay grasses after molting, while still soft.

26. www.chesapeakebay.net SAV plays an important role in the environment • SAV produces oxygen in the water column as part of the photosynthetic process.

27. www.chesapeakebay.net SAV plays an important role in the environment • SAV produces oxygen in the water column as part of the photosynthetic process. • Dissolved oxygen is essential for animals living within the Bay.

28. www.dnr.state.md.us SAV plays an important role in the environment SAV traps sediment that can cloud the water and bury benthic organisms, such as oysters.

29. John Melton SAV plays an important role in the environment SAV protects shorelines from erosion by slowing down wave action and by anchoring sediment with its roots and rhizomes.

30. John Melton John Melton SAV plays an important role in the environment • SAV requires nitrogen and phosphorus for its growth and reproduction. • Thus SAV helps to prevent these nutrients from being used to fuel the (unwanted) growth of algae. • As the amount of algae is reduced, water clarity is improved. SAV absent SAV present

31. SAV plays an important role in the environment SAV makes a significant contribution to ecosystem production; it has annual production rates per square meter similar to that of agriculture.

32. We have talked about what SAV is … What is SAV and Why Should I Care? and we have discussed the importance of SAV. Next: What’s the Problem and What Can I Do?