JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility - PDF document

JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility Inauguration 16 July 2019 Seagrass v Seaweeds (Algae)  Kreol: both = “Gomon”  Seagrass = Flowering plants (~55 species worldwide) Seagrass Ecosystems:  Flowers & seeds Beyond the Confines of the Meadows  Vascular plants with roots, stems, leaves  Seaweeds = Multi-cellular algae (~5,000-6,000 spp worldwide)  Little or no vascular tissue Dr. Jeanne A. MORTIMER Island Conservation Society (ICS) 1 2 Seagrass or Algae? Seagrass or Algae? 3 4 Seagrass Map of the World What is a seagrass?  Flowering plants  Not true “grasses”  Special features :  Grow underwater  Disperse pollen & seed underwater (most plants, even aquatic plants, disperse above water)  4 families worldwide :  Seychelles: 2-3 families  ~60 species worldwide:  Seychelles: 9-12? species 5 6 1

JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility Inauguration 16 July 2019 Seagrasses of Seychelles: Most common species Seagrasses of Seychelles: other species Thalassodendron Thalassia Cymodocea Cymodocea Syringodium Halodule Halophila Halophila ciliatum hemprichii rotundata serrulata isoetifolium uninervis ovalis decipiens 7 8 Seagrasses of Seychelles: most endangered Ecological Services of Seagrass Ecosystems Habitat for Sea Turtles Food for Sea Turtles Hawksbills (Eretmochelys imbricata) Green turtles (Chelonia mydas)   Only in the Inner Islands: -- Praslin Habitat for Commercially Important Fishes -- Mahé Enhalus acoroides = “Tape Seagrass”  e.g., Rabbit fish 9 10 Ecological Services of Seagrass Ecosystems Ecological Services of Seagrass Ecosystems Good for corals Good for corals  Produce lots of organic carbon: take up CO2 & give off O2 - good for corals  Bind sediments (esp. during storms) – good for corals  Bind organic pollutants  Protect coastlines from erosion  Remove carbon dioxide from ocean-atmosphere system =  Below ground biomass > Above ground biomass “ Blue Carbon Sinks ”  Blades baffle currents, encourage sediment settlement o Reduce impact of climate change o Increases pH levels in vicinity – makes H2O less acidic - T ropical seagrasses may tolerate higher temperatures, so may good for corals   Coral calcification can be 20% greater downstream of remain productive even as climate warms seagrass Seagrass conservation enhances resilience of coral reef biodiversity  11 12 2

JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility Inauguration 16 July 2019 Seagrass Survey Protocol: Poivre Atoll : shallow water Quadrat sampling: 50 cm x 50 cm square  surveys Thrown randomly at intervals  --early Dec 2017 Record:   GPS location --low spring tides  Photo  Sediment type -- 3 spp seagrass  T otal seagrass over (% of total) -- evidence of turtle  % Contribution per seagrass spp  % Macro-Algal cover cropping  Associated Fauna  Canopy Height (cm) 13 14 Beautiful seagrass pastures in Seychelles Poivre reef-flat seagrass survey Thalassodendron ciliatum -- among the tallest canopies in world -- > 100 cm tall 15 16 Washes up on beach, fertilizes vegetation Nekton Expedition Seagrasses & Algae -- to what depth? Differences among island groups? Previous records ~37m 17 18 3

JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility Inauguration 16 July 2019 Nekton Expedition Activities Neuston Sampling Relevant to Seagrass & Algae study:  Snorkel & SCUBA surveys (including in seagrass meadows)  Neuston Sampling of the surface waters  Deep sea Surveys 19 20 Neuston Sampling Neuston Sampling 21 22 Deep Sea Surveys Deep Sea Surveys Submersibles: • Operated from 30 m to 250 m • Video records of all dives using several cameras ROVs operated up to 450m 23 24 4

JA Mortimer: Seagrass Ecosystems. Coral 8/22/2019 Facility Inauguration 16 July 2019 Dead Seagrass Leaves at all depths: In Summary:  Seagrass important to most marine ecosystems in Seychelles: ROV screen shot Seagrass meadows themselves (& associated species)  ~300 m Beach vegetation (prevents erosion; provides nutrients)  Blue Carbon Sink: Coral reefs (binds sediments; less acidity; adds O2)  Carbon Sequestration: Surface waters (habitats for small organisms)  i.e., keeps Carbon out Deep sea (provides nutrients)  of the atmosphere Serves as Blue Carbon Sink that keeps Carbon out of Atmosphere 25 26 Thank you! 27 5