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Home , Posidonia, Posidonia oceanica, Ruppia, Seagrass

The

Kim Peyton University of Hawaii - Manoa Department of Botany Novel floral have led to new types of , functions, and wetland faunal niches. Greb et al. (2006) What is a ?

•Submerged Aquatic Vegetation (SAV) •Marine angiosperms •Herbaceous monocots •Functional grouping of Outline

• Anatomy • Characteristics of seagrasses • & systematics • Evolution of seagrasses • Distribution of seagrasses • Hawaiian seagrasses •Seaggyrass diversity • • Reproduction • FdFood sources • Annual Production Estimates • Stressors of seagrasses • Ethnobotany Anatomy • Blades - Nutrient uptake • Short shoot = stem • - Anchoring Propagation Nutrient absorption Gas e xchange • - Nutrient uptake Anchoring Gas exchange Vegetative Morphology

• : strap-like to oval • bundles • Short shoots Conveyor-belt growth Characteristics of Seagrasses: Functional Group Arbor (1920) & den Hartog (1970)

1. Adapted ecologically to varying salinities = osmoregulation 2. Able to grow while completely submerged (vs. emergent vegetation) 3. Resistant to waves & tidal currents 4. Adapppted to pollinate underwater = hydrophilly 5. Competitive in the marine environment The & Lepilaena Problem

• 5th seagrass characteristic effectively removes Ruppia & Lepilaena from the seagrass designation • Freshwater - brackish - marine How extraordinary are seagrasses? How extraordinaryyg are seagrasses? Aquatic angiosperms

• 17% of the families • 1. 5% of the genera • 2% of the species

But over 100 independent origins are estimated - diversity measured differently How extraordinary are seagrasses? How common is hydrophily?

• 130 species of 300,000 species • Hydrophiles = 0.04% • 60 species are marine = seagrasses • Seagrasses = 0.02% How extraordinary are seagrasses?

1. Correlation between marine and hydrophily 2. Reflects difficult evolutionary transitions Where did seagrasses come from?

Halophytes SAV - emergent - freshwater

Seagrasses rbcL marker (Les etlt al 1998)

• 3 lineages • 5 families • 12 genera • SAV ancestry

Can you find Ruppia? Distribution of Seagrasses

Temperate - Boreal Regions • 4 genera •~ 28 spec ies Tropical - Subtropical Region • 7 genera • ~ 30+ species Eurythermal • Ruppia • ~ 2-10 spp. Facultative successional sequence spans coastal wetlands ( forests), seagrass meadows and reefs.

Origins of this relationship found in the late with the first appearance of seagrasses and .

(Brasier 1975; McCoy & Heck 1976) The seagrasses of Hawaii

Halophila decipiens

Halophila hawaiiana

Ruppia maritima Tropical wetlands (mangroves) - seagrass meadows - coral reefs:

Shared succession coupled with integrated tropic relationships Shared Pan-Tethyan Coastal wetlands (mangroves) - distribution: - coral reefs • seagrasses • cor al r eef fi sh es • decapods • foraminifera • mollusks • McCoy & Heck 1976; Brasier 1975; Domning et al. 1982

Seagrass Diversity Enhalus

Halodule

Posidonia Halophila Habitats: Soft Sediment

Leaves reduce flow Particulate matter drops out Rhizomes - sediment accumulation Roots - stabilization Habitat for infaunal organisms Habitats - Hard Bottom

Rocky Inner Tidal Phyllospadix Late s uccessional species Seagrass Fruits & Seeds

Bird dispersed Phy llospa dix ZtZostera & Ruppia fruits Large seeds

•Fruits with hooked barbs •Macroalgae •Roots sticky Turner (1983) Vegetative fragments Seagrass as a food source: Grazers Smaragdia spp.

Waterfowl

Dugongs & Manatees Green Turtles Seagrass as a food source: suspension & deposit feeders

• Few direct grazers (temperate) • Sequestered nutrients • Litter • 10 tons leaves per acre per year • 50 million infauna per acre Estimated Annual Production & Bla de Elonga tion Ra te: Flor ida Virnstein (1982)

Halodule beaudettei 182 - 730 g C m-2 y-1 ~3.1 mm/d filiforme 292 - 1095 g C m-2 y-1 ~8.5 mm/d testudinum 329 - 5840 g C m-2 y-1 ~2-5 mm/d Anthropogenic Stressors

Sewage discharge Non-point pollution Alga l ep ip hy tes Reduction of PAR Invasive Species

Caulerpa taxifolia - cultured strain Mediterranean ; California; oceanica - endemic seagrass Aquarium dumping Hawaiian flora reflects isolation Background Halophila hawaiiana Limu enenue

•Endemic species • 2-3hiht3 cm canopy height • Builds perennial mounds (den Hartog 1970)

Depth Distribution: 1-90 ft Invasive species and the seagrasses of Hawaii: Disppglacement & Smothering

Gracilaria salicornia Gracilaria sp. Florida

Halophila decipiens

Halophila hawaiiana

Ruppia maritima Avrainvillea amadelpha Maunalua Bay - East Honolulu

Urbanized watershed WtWater d epth th13 1.3 m Methods - Removal Experiment Halophila hawaiiana & Avrainvillea amadelpha

• Established 25 0.25 m2 fixed plots with 10 treatments, 10 controls with alga & 5 controls without alga • Treatments - Avrainvillea is removed • Quantified % cover and blade pair densities (Morris et al. 2000) • Monitored over 120 days • June 2004 to October 2007 + June 2004 to June 2008 Invasive Removal Results

100 * June 2004 80 * October 2004 January 2005 Cover June 2005 60 October 2005 January 2006 40 June 2006 Percent nn October 2006

20 June 2007 Mea October 2007

0 Seagrass Seagrass Invasive alga Invasive alga Seagrass Invasive alga (Treatment) (Invasive (Treatment) (Invasive (Seagrass (Seagrass Control) Control) Control) Control) Invasive Removal Results

100 * June 2004 80 * October 2004 January 2005 Cover June 2005 60 October 2005 January 2006 40 June 2006 Percent nn October 2006

20 June 2007 Mea October 2007

0 Seagrass Seagrass Invasive alga Invasive alga Seagrass Invasive alga (Treatment) (Invasive (Treatment) (Invasive (Seagrass (Seagrass Control) Control) Control) Control) A line in the sand - in which direction is the invasion going?

June 2004 Avrainvillea

June 2008

June 2004

Seagrass Sand Blow-out in Seagrass Meadow

Limu Sand Blow- out in Seagrass Meadow

Natural Dist u rbances:

Tree fall in a forest Forest fire Land slide Volcanic eruption Waikiki Site Descriptions: Dredged Areas

1 = Impact Site 2 = Control Site • Discontinuous • >3300 m2 continuous meadows of 57 m2 meadow & 21 m2 • 2.5-3.5 m water • Seagrass depth confined to upper 2 • Occasional ppgortions of dredged fragments of G. slope in 2-2.5 m salicornia water depth • G. salicornia Hard bottom tumbleweeds at 3- 3.5 m water depth 1 Gracilaria salicornia - Negative impacts in a Halophila decipiens meadow? The invasive alga Gracilaria salicornia The invasive alga Gracilaria salicornia

G. salicornia fragments can grow into tumbleweeds. Results, so far

Control Site Impact Site • >3300 m2 • Discontinuous continuous H. meadow of H. decipiens meadow decipiens 57 m2 & 21 m2 • 3-3. 5 m w ater depth • 2-2.5 m water •No G. salicornia depth • Honu feeding area • G. salicornia present 3-3.5 m watdthter depth Seagrass results , so far

9000

8000

7000

6000

5000 af pairs/m2

ee 4000

3000 Mean l Mean 2000

1000

0 Control Impact

100

90

80

70

60

50

40

Mean dry wt/m2 30

20 n=10; n.s. 10 0 Control Impact Seagrass results, so far

4000

3500 22 3000

2500

r of fruits/m 2000 ee

1500

1000 Mean numb

500

0 Control Impact n=10; p<0.00001 Ruppia maritima Bristle-Thighed Curlew flipping matfts of RiRuppia on MlkiMolokai

A. Dibben-Young Ruppia is present in some wetlands and absent in others. Why?

Experiments

Two experiments: •Each at two sites •Both tilapia genera Test for other factors

Exclosure experiment

n = 6 4 Levels

Cage experiment Results

CtlControl Large Tilapia Small Tilapia

Day 0 Day 0 Day 0

Day 6 Day 6 Day 6 Results: Cage Experiment

Large tilapia consume Ruppia

60

50

40

30

eight (g) 20 Tilapia Large

WW Tilapia Small 10 Top Minnow Large Top Minnow Small 0 No Control nge Wet aa Treatments -10 % Ch -20

-30

-40 Ethnobotany of Seagrasses

• Non-flammable insulation - both thermal & sound-proofing US&UKUS & UK • Roofing thatch - slow to rot & flea proof UK • Binding soils - dikes in the Netherlands & stabilize sand dunes • Stu ffing i n p illows, ma ttresses & up ho ls tery Europe & US • Packing material for seafood - Zostera japonica • Rain gear - Phyllospadix - pre-rubber Japan • Hawaii as bait