Coral Reef Ecosystems - PowerPoint PPT Presentation

Loading...

PPT – Coral Reef Ecosystems PowerPoint presentation | free to download - id: 601ee1-MzlmO



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Coral Reef Ecosystems

Description:

Coral Reef Ecosystems Ecology and Environmental Management Lecture content Coral reef ecology How they are formed Physical Environment Diversity patterns Threats to ... – PowerPoint PPT presentation

Number of Views:129
Avg rating:3.0/5.0
Slides: 59
Provided by: davidba150
Learn more at: http://homepages.abdn.ac.uk
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Coral Reef Ecosystems


1
Coral Reef Ecosystems
  • Ecology and Environmental Management

2
Lecture content
  • Coral reef ecology
  • How they are formed
  • Physical Environment
  • Diversity patterns
  • Threats to coral reefs
  • Fisheries
  • Coral reef management
  • Assessing damage
  • Management for ecology and economics
  • Diversification
  • Tourism

3
Introduction to coral reefs
4
What is a coral reef
  • Biological (coral community)
  • Organic, Biogenic
  • Coral and Algal communities
  • Mostly hermatypic corals, algae, and other
    sessile animals
  • Geological features (reef)
  • Carbonate
  • In situ buildup
  • Topographic relief
  • Wave resistant
  • Cemented, consolidated

5
Corals
  • Phylum Anthazoa
  • Class Cnidaria
  • Hermatypic (hard) corals contain symbiotic algae
  • Up to 500 spp. at some sites

Rosen 1981
6
Building the reef
CaCo3 addition - CaCo3 loss Accumulation
Biological erosion Mechanical erosion Sediment
export, dissolution
Reef Growth
Biogenic production Sediment Import Cementation
Kleypas et al 2001
7
Types of reef
  • Fringing, Barrier, Atoll, Drowned

8
Environmental requirements
  • Physical environment
  • Temperature of 25-31oC (limited Northwards by the
    18oC minimum isotherm)
  • Salinity of 34-37 ppt
  • Light level
  • Predominantly in top 30 m of water
  • Biological environment
  • Oligotrophic, highly stratified water column

9
  • Coral reef distribution

10
Coral diversity patterns
11
Maps
  • For the lecture I used maps from a variety of
    locations, often more for clarity than scientific
    detail. I would recommend the maps from the
    World Conservation Monitoring Centre
    (www.wcmc.org.uk) which I would tend to value as
    reliable.
  • The main point being that the high population
    densities in many coastal areas which contain
    high coral reef species richness represent a
    serious threat.

12
Fish community
  • Mainly Perciform teleosts
  • 2 faunas, Diurnal and Nocturnal
  • Often territorial/site attached
  • Intraspecific interactions (pair bonding and
    harems) and interspecific mutualism (e.g.
    cleaning stations)
  • Mostly planktonic larvae
  • Estimated 4500 spp, 25 of marine total
  • 10 of world fishery landings

13
Fishery species
  • Often large, high-value fish

14
Fish distribution patterns
15
World population distribution
16
And if that wasnt bad enough..
17
Threats to coral reef systems
  • Overpopulation
  • Unsustainable fisheries
  • Coastal development
  • Global climate change

18
Coral reef fisheries
  • Essential to survival of many
  • Managed sustainably for generations
  • Diverse ecosystem
  • Multispecies fisheries
  • Interspecies interactions may invalidate models
  • Collection of sufficient data for all species may
    not be practicable
  • Reduction of fishing effort to sustain all fish
    species wastes the productivity of most stocks

19
Non-selective and destructive fishing methods
  • Subsistence fishing occurs regardless of effort
    required
  • Muro Ami, Dynamite (Blast), and cyanide fishing
  • Trawling
  • Trapping and lines
  • Ghost fishing
  • Total fishing mortality often not known

20
Malthusian overfishing
  • ...occurs when poor fishermen, faced with
    declining catches and lacking any alternative
    initiate wholesale resource destruction in order
    to maintain their incomes.
  • This may involve in order of seriousness, and
    generally in temporal sequence...

21
  • 1) Use of gears and mesh sizes not sanctioned by
    government
  • 2) Use of gears and mesh sizes not sanctioned
    within the fisherfolk community
  • 3) Use of gears that destroy the resource base
  • 4) Use of gears such as dynamite or sodium
    cyanide that do all of the above and even
    endanger the fisherfolks themselves

McManus 1997
22
Ecosystem effects of fisheries
  • Removal of predators
  • Removal of algal grazers
  • Change in dominance
  • Californian Sea Otters
  • Urchins
  • Crown of Thorns starfish COTS (Acanthaster
    planci)
  • Changes in size frequency of animals

23
Crown of Thorns Starfish
24
Crown of Thorns
  • Eats coral by everting gut
  • Aggregations can remove 95 of coral cover
  • May result in collapse of remaining skeleton
  • Pheromone controlled aggregated spawning
  • Recovery takes at least 12 years
  • Caused by loss of predators?
  • Increased larval survival due to pollution?

25
Terrestrial impacts
  • Pollution
  • Sewage
  • Agriculture
  • Aquaculture
  • Rubbish
  • Sedimentation
  • Eutrophication
  • Construction on reef flats
  • Coral mining
  • Mangrove destruction

26
Climate change
  • Potential impacts on coral communities
  • Changes in water temperature
  • Increases in CO2 concentration
  • Changes in solar irradiation (if cloud cover
    changes)
  • Sea level rises leading to drowning of reefs
  • Changes in surface run-off (sedimentation)
  • Changes in land-use patterns leading to increased
    reef exploitation

Kleypas et al 2001
27
Coral bleaching
  • Loss of symbiotic algae
  • May cause death of animal
  • A symptom of climate change?

28
Coral Bleaching
  • First described in 1984
  • Multiple re-occurrences at same sites
  • New sites impacted during 1990s
  • Many known triggers
  • Temperature (especially increases)
  • Solar radiation (especially UV)
  • Combination of UV and temperature
  • Reduced salinity
  • Infections

29
Effects of bleaching
  • Loss of symbiontic algae (Zooxanthellae) algae
    by
  • Degradation In situ
  • Loss of algae by exocytosis
  • Expulsion of intact endodermal cells containing
    algae
  • Resulting impacts
  • Vary between species, and even parts of the same
    colony
  • Loss of sensitive species (especially Acropora
    spp.)
  • Recovery slow and highly variable between sites

30
The Problems
  • A large (and growing) number of people are
    dependent on coral reefs
  • Management of a multispecies fishery is extremely
    complex, and often fails
  • Terrestrial development may destroy coastal reef
    systems
  • Global climate change may exert new pressures

31
Coral reef management
32
Management Issues
  • Biological
  • What does the resource consist of?
  • What state is it in?
  • Is there overfishing?
  • Is there habitat destruction?
  • Socio-ecomomic
  • Levels of resource exploitation
  • More sustainable ways of exploiting the resource
  • Alternatives to coral reef exploitation/damage

33
Monitoring coral reefs
  • What sites and parameters to monitor?
  • Fish
  • Macroinvertebrates
  • Water quality
  • Benthic habitat quality
  • Coral health

34
Sources
  • Australian Institute for Marine Science (AIMS)
    website contains all their standard techniques.
    From a comparability point of view it is
    extremely helpful to use common techniques.
  • The AIMS site and their manual (English et al,
    1997) even explains how to store the data in a
    database and manage it. Essential reading if you
    can get hold of it.
  • The use of volunteers for some types of coral
    reef survey work is very common and slightly
    controversial. Common sense will be necessary in
    determining what techniques a volunteer can apply
    - in particular for qualitative judgements about
    reef quality and levels of impact.

35
Large-scale studies
  • Rapid Ecological Assessment
  • Manta tows
  • Estimates of cover (live and dead coral)
  • Abundance of highly visible species
  • Human impacts
  • Mapping and aerial photography

36
Monitoring fish
  • Visual census
  • Transects
  • Point counts
  • Random searching
  • Often allow biomass estimates
  • Fisheries monitoring

37
Monitoring the benthos
  • Line intercept transects
  • Visual transects
  • Quadrats
  • Photography and video

38
Line Intercept Transect
39
Marine protected areas
  • Fisheries reserves
  • No take zones (NTZs)
  • Controlled fishing
  • Effects on fish populations
  • Coral reef fish often have small ranges
  • Effects on fishing revenue
  • Local management and ownership

40
Sources
  • The marine protected areas case studies are based
    on the work of Russ and Alcala.
  • I think these are classic studies because they
    show both the conservation and economic benefits
    of marine reserves AND how important co-operation
    with the local community can be.
  • These are not new references, work from Robertss
    paper for newer studies. See also Gell and
    Roberts 2003 Trends in Ecology and Evolution,
    18, 448 - 455

41
Biological effects of protection
  • Habitat protection
  • Biodiversity
  • Protection of vulnerable species
  • Allow fish to grow to maturity
  • Control (reference) sites

42
Economic effects of protection
  • Increased size and abundance of stock species
  • Emmigration into fishing grounds (Spillover)
  • Insurance against management failure
  • Tourism spin-offs
  • Ease of enforcement

43
Marine reserves case study
44
Effects on fish diversity
45
Effects on fish abundance and biomass
46
Factors to consider
  • Costs?
  • Staff, setup, monitoring
  • Initial loss of fishing revenue
  • Size/shape of reserve?
  • Life history and behaviour of fish
  • Fishing intensity
  • 20-40 of fishing ground
  • Can you sell it?
  • Any spin-off benefits?
  • Employment of local staff?
  • Compromise on size of reserve?
  • What management outside reserve?

47
Impacts of tourism
  • Terrestrial development
  • Land reclamation and creation of beaches
  • Mangrove removal
  • Sand on reef flat
  • Boats
  • Anchors
  • Diver/snorkeller impacts and fish feeding
  • Sewage
  • Harbour dredging

48
Ras Mohammed project
49
Growth of reef tourism
50
Sources
  • This section is based on the works of David Medio
    and Julie Hawkins. A couple of their references
    are included at the end.
  • Much other material is directly from the Egyptian
    Environmental Affarirs Agency (link at the end)

51
Divers reduce coral cover
52
.and scare away fish
53
Reducing diver impact
  • Mooring buoys
  • Most damage caused my minority of divers
  • Education
  • Enforcement
  • Ban gloves
  • Monitoring
  • Zoning / Closure / Rotation

54
Managing terrestrial impacts
  • Catchment management
  • Agriculture
  • Fertiliser
  • Seafront corridors
  • Controls on sewage systems
  • Limits on development
  • Dry beaches and walkways

55
Who cares what happens to coral reefs anyway?
  • Fisheries
  • Tourism
  • Coastal protection
  • Bioprospecting
  • Moral reasons
  • Many coral reef functions are Subsistence
  • Do not show up as economic benefits
  • REPLACEMENT value may be extremely high

56
Summary
  • Coral reefs contain diverse fish and invertebrate
    assemblages
  • This makes them valuable, but difficult to manage
  • Coral reefs are mainly found in the poorest areas
    of the world
  • This makes them prone to over-exploitation

57
Summary
  • Reefs must be assessed and monitored to allow
    management
  • Marine protected areas may protect biodiversity
    and maintain fish stocks
  • Diversification of local economies may be
    effective in reducing pressures
  • Tourism brings new pressures which must also be
    managed.

58
(No Transcript)
About PowerShow.com