Marine Biodiversity: patterns, processes and conservation issues

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Marine Biodiversitypatterns, processes and
conservation issues

• John S. Gray
• Dept of Biology University of Oslo
• Norway

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The Patterns
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Marine Diversity Paradigms(from Levinton 1995 p
347-9)

• 1. The best known diversity gradient is an
  increase of species diversity from high to low
  latitudes in communities of shelf benthos, and in
  the plankton
• 2. In both benthic and water column assemblages
  the open sea tends to have more species than do
  inshore habitats
• 3. Diversity of macroinvertebrates and fish
  increases with depth to just seaward of the
  continental rise and then decreases towards the
  abyssal plain.

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Sanders Diversity Data (1968)
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Deep-sea data from New Jersey, USA, (Grassle
Maciolek 1992)
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Frigg oilfield, Norway
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Bass Strait, Australia
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Species diversity of deep-sea
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Species diversity of coastal sediments
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Conclusions The Shallow-Deep Gradient

• The number of individuals per species is much
  lower in the deep sea (mean 52) than at the coast
  (mean 335 )
• Species density (number of species per unit area)
  is higher in the deep sea than coast
• Species richness decreases below 1500-2000m
• Coastal areas have a greater number of habitats
  than the deep sesa and overall must have higher
  species richness

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Data (number of species) on which paradigm of the
Latitudinal Diversity Gradient is based
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Latitudinal Diversity in the Deep Sea (Rex et al
1993)
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Latitudinal gradient of estuarine benthos
(Attrill et al 2001)
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Latitudinal Diversity Gradient(from Roy et al
1998)
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Bivalve species richness (Crame, 2000)
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Bivalve species richness (Crame, 2000)
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Conclusions from Crames study

• Old bivalve clades do not show a latitudinal
  gradient
• Young clades (especially the heteroconchs) show
  steep latitudinal gradients
• This suggests that species arise, primarily in
  the tropics (China-Indonesian region), and
  radiate from here
• Low Arctic species richness is probably because
  the species have not yet reached there

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Approximate species numbers in the Southern
Ocean, (from Arntz et al 1997)
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Biodiversity of Norwegian continental shelf
(Ellingsen Gray 2001)
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Alpha species richness
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Species accumulation curvesNorwegian
continental shelf
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Europe 125,000 b.p. Temperature 2oC warmer than
today (from Andersen Borns 1997)
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Europe 20,000-17,000 years b.p.(from Andersen
Borns, 1997)
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Europe and Arctic 15,000 years b.p.(from
Andersen Borns, 1997)
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Europe and Arctic 11,000-10,000 years b.p. (from
Andersen Borns, 1997)
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The ProcessesDoes more diversity lead to
increased rates of functional processes?
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Species richness function(Naeem et al Nature
368 1994)
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Species richness function (Naeem et al Nature
368 1994)
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Species richness function (Naeem et al Nature
368 1994)
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Species richness function(Emmerson et al. 2001
Nature)
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Effect of species richness compared with single
species(Emmerson et al 2001 Nature)
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Plant species and production(Schaffers 2002
Plant Ecology)
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Endangered species and production(Schaffers 2002
Plant Ecology)
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Rare species and production(Schaffers 2002 Plant
Ecology)
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25 Biodiversity Hotspots(Myers et al 2000 Nature)
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Conservation IssuesWhat aspects of marine
conservation do we need to emphasise?
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The Threats to Marine Biodiversity

• Eutrophication (Red Tides)
• Effects of contaminants (especially oestrogenic
  mimic hormones)
• Habitat degradation, fragmentation and
  destruction
• Fishing and especially trawling
• Climate Change

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Threats Red Tides
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Imposex in Nucella lapillus
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Frequency of Imposex in S.W England
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Endocrine Disruptors
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Habitat degradation Lamma beach
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Reclamation ( coastal habitat destruction)
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Reclamation Habitat destruction
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The value of undisturbed coastal systems
(Costanza et al 1997 Nature)

• Estuaries US 22,832 ha-1 yr-1
• Seagrass algal beds US 19,004 ha-1 yr-1
• Tidal Marshes/mangroves US 9,990 ha-1 yr-1
• Swamps floodplains US 19,580 ha-1 yr-1
• Coral Reefs US 6,075 ha-1 yr-1
• Continental shelf US 1,610 ha-1 yr-1
• Total value of coastal services US 12,568 yr-1
  x 109

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The greatest threat Trawling
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A full trawlPicture from Greenpeace Web site
www.greenpeace.org
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Trawling Before
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Trawling After
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Trawling Before
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Trawling After
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Trawl marks on seabed (Side-scan sonar from
Thomas Lundalv)
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Endemic species(Myers et al 2000 Nature)
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Biodiversity of Norwegian continental shelf
(Ellingsen Gray 2001)
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Species ranges Norwegian continental shelf
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Species range Hong Kong(Data from Paul Shin)
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Bivalve species richness (Crame, 2000)
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Biodiversity and Human Populations(Cincotta et
al 2000 Nature)
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Marine conservation in S.E.Asia

• Here is the greatest marine diversity in the
  world
• Human population and resulting environmental
  pressures are extremely high
• Intact coastal habitats are economically highly
  valuable
• Habitat destruction and degradation are the major
  problems to be tackled

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Marine conservation in S.E.Asia

• The focus needs to be on a wider range of species
  than just e.g. dolphins and corals
• Habitat preservation and restoration are the key
  aspects of successful conservation
• More research is needed on the patterns of
  biodiversity and especially how species richness
  changes with scale
• Our latest research suggests that in sub-tropical
  areas although regional species richness is
  similar to that of temperate areas, richness
  changes more rapidly with distance in subtropical
  areas.