The Global Crisis of Seagrass Decline

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The Global Crisis of Seagrass Decline Fred
Short, Ph.D. Department of Natural
Resources NRESS Program Chair SeagrassNet,
Director
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What are seagrasses ?
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Nemo in seagrass near a coral reef -- Papua
New Guinea
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Stingray over turtle grass -- Belize
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Seagrass and mangroves - Australia
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Eelgrass in the Great Bay Estuary -- New
Hampshire / Maine
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Grad student in eelgrass -- Portsmouth, NH
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How does seagrass differ from other marine
plants?
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Cymodocea
Enhalus
Halophila
Thalassia
Halodule
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• 2003

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Seagrass provides critical habitat in temperate
regions
G. Pergent
G. Kendrick
Seahorse (Hippocampus) In Cymodocea
meadow, Mediterranean Sea
Zebra fish (Girella) In Posidonia meadow, Perth,
Western Australia
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Seagrass is a critical food source in tropical
regions

J. Kenworthy
R.P. van Dam
Dugong (Dugong) In Halophila meadow, Red Sea,
Egypt
Green Sea Turtle (Chelonia) In Cymodocea
meadow, Yucatan, Mexico
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FUNCTIONS VALUES

• 1) primary production
• 2) nutrient uptake storage
• 3) oxygen production
• 4) habitat
• 5) benthic production
• 6) filtration

• 1) improves water quality
• 2) creates food webs
• 3) provides nursery habitats
• 4) supports fisheries

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Where are seagrasses found?
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Global Seagrass Biodiversity
Short, F.T, W.C. Dennison, T.J.B. Carruthers, M.
Waycott. 2007. Global Seagrass Distribution and
Diversity A Bioregional Model. Journal of
Experimental Marine Biology and Ecology 350 3-20.
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Seagrass Global Bioregions
Short, F.T, W.C. Dennison, T.J.B. Carruthers, M.
Waycott. 2007. Global Seagrass Distribution and
Diversity A Bioregional Model. Journal of
Experimental Marine Biology and Ecology 350 3-20.

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What causes seagrass decline?
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Trawling
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Moorings and dredging
Sept 2003
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Fishing boating activities
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Sedimentation - Road construction in Palau
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Pressures to seagrass increased nutrient input
(Fertilizer and sewage)
Fertilizer applied in agriculture
Fertilizer applied to lawns
Wastewater Treatment Plant
Orth et al. 2006. Bioscience 56 987-996
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Seaweed
Nutrients - Nuisance Seaweeds
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Nutrients - Phytoplankton
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Water quality and light
Good
Fair
Awful
Poor
death
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And of course Climate change ! another human
impact
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Is there a global seagrass crisis of decline?
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Eelgrass Monitoringin New Hampshire, USA
NH Port Monitoring - Piscataqua River
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What is the cause of decline?
From NHState of the Estuary Report 2006 - NHEP
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Global seagrass decline
58 of sites declining
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Seagrass Global Bioregions
Short, F.T, W.C. Dennison, T.J.B. Carruthers, M.
Waycott. 2007. Global Seagrass Distribution and
Diversity A Bioregional Model. Journal of
Experimental Marine Biology and Ecology 350 3-20.

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Global Seagrass Monitoring based at UNH
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Goals of SeagrassNet

• To assess the impacts of human activities on
  seagrass ecosystems

• To assess the impacts of global climate change on
  seagrass ecosystems

• To increase seagrass awareness worldwide

Indonesia
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• Quarterly sampling
• Fixed transects (intertidal or SCUBA)
• Methods developed from the Global Seagrass
• Research Methods (Short and Coles 2001)

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Transect (site) location
TRANSECT (site)
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Komodo, Indonesia
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SeagrassNet - 79 sites
SeagrassNet - 98 sites
www.SeagrassNet.org
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Collectingdata sinceJuly 2001
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Pohnpei, Micronesia
Inhaca Island, Mozambique
2007
Wadi Gemal, Egypt
Eilat, Israel
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Establishing a Baseline
N 5
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N6
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The Cause
Freeman, AS, FT Short, I Isnain, FA Razak, RG
Coles. In revew. Seagrass on the edge
land-use practices threaten coastal seagrass
communities in Sabah, Malaysia. Biological
Conservation.
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SeagrassNet monitoring across the Americas case
studies of seagrass decline
Short, F.T., E. Koch, J.C. Creed, K.M. Magalhaes,
E. Fernandez, J.L. Gaeckle. 2006. SeagrassNet
monitoring across the Americas case studies of
seagrass decline. Marine Ecology 27277-289.
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• New Hampshire
• Climate change
• -
• goose grazing

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Placencia Village Belize Nutrient loading
from tourist development
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Tamandaré Brazil Climate change - storm
frequency/ shifting sediment
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SeagrassNet Global Report Card
Decline (n11) Increase (n0) No change
(n22) Lack of data (n37)
Change in Percent Cover
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Seagrass species showing decline at SeagrassNet
sites
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Causes of decline globally Sediment loading
Nutrient loading Climate change Direct
physical damage
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http//www.SeagrassNet.org/