SALT MARSHES BIOL 200 MARINE BOTANY FALL 2009
WHAT ARE SALT MARSHES? • Salt-tolerant plants • Tidal marshes • Plants of low-energy coasts Distribution-worldwide –subtropical to arctic waters.
WHAT IS THE ECOLOGICAL IMPORTANCE OF MARSHES? • Direct food source for a wide variety of animals and insects. • Form part of the detrital food chain. • Habitats for animals (marsh fauna). • Stabilize colonial sediments • Filter organic wastes and reduce nutrient loading.
TAXONOMY Grasses, Sedges, Rushes
GRASSES, SEDGES, AND RUSHES • Wind-Pollinated • Flowers do not have showy petals and are often reduced • Pollen is light • Stigmas are feathery
GRASSES-POACEAE Cylindrical and hollow stems Leaves are alternate and in 2 ranks
SEDGES-CYPERACEAE • Triangular, solid stems • Leaves in 3 ranks
RUSHES-JUNCACEAE • The Rushes are in the order Liliales and have many similar features to Lily flowers, except that the petals and sepals are small, brown and scale-like and are called tepals.
COMMON SALT MARSH FLOWERING PLANTS • Spartina alterniflora (smooth cordgrass) • Juncus roemerianus (black rush) • Salicornia virginica (glasswort)
Smooth Cordgrass • Erect stem can grow to 3 m (tall form) • Horizontal rhizome—produces the stems and roots • Lacunae in stems • Krantz anatomy
KRANTZ ANATOMY • C4 photosynthesis = spatial separation • C4 plants have unique morphology called Krantz anatomy • - Mesophyll cells fix CO2 with PEP carboxylase • - Bundle sheath cells make carbohydrate by Calvin cycle
Black Rush • Clonal plant with rhizomes, erect stems, and a fibrous root system • Rhizome is covered by suberized scale leaves and has lacunae. • Needle like leaves • Rush-type flowers-cymes
Glasswort • Stems and leaves are very succulent • Glossy in appearance • Stems produce short, erect branches • Leaf blades are reduced to scales.—petioles have a segmented appearance.
OTHER SALT MARSH PLANTS • Ferns—Acrosticum • Bryophytes-mosses and liverworts • Algae—sediment microalgae, macroalgal mats, and epiphytic macroalgae. • Seagrasses
HOW DO PLANTS REGULATE SALT? • Ion exclusion in the roots • Growth and succulence • Shedding • Secretion through glands • Secretion through roots • Lowering water loss by reducing transpiration –CAM plants
WHAT ARE SOME OF THE THREATS TO MARSHES? • Agricultural • Urban Expansion • Pollution from other sources • Invasion by exotic species
REFERENCES • www.dep.state.fl.us/coastal/habitats/saltmarshes.htm • www.dnr.state.sc.us/marine/pub/seascience/dynamic.html • www.nearctica.com/ecology/habitats/estuary.htm • www.conservancy.co.uk/learn/wildlife/saltmarsh.htm
Assignment • Select a salt marsh ecosystem in the USA. Outline the problems that are adversely impacting that particular ecosystem. Devise a management plan for restoration of your chosen ecosystem. Prepare a power point presentation and be ready to present in your next class. Each student will have 5-6 minutes to present.