2. Introduction
Productivity- the rate at which new materials are
produced from their precursors by living things; new
tissues, offspring, carbohydrates that leak from a cell
Productivity of an organism or population- rate at
which it turns resources into more of itself
3. Productivity- represents the flux of nutrients from
environment into living organism
Highly productive environment- organisms won’t
have to travel far to get sufficient food
Less productive environment- have less food,
support fewer numbers of individual
4. Productivity of an ecosystem- net primary
productivity
The sum of all net production of all species of primary
producers
Expressed as- dry wt of production in grams of
carbon/m.sq/yr (gm¯²y¯¹)
5.
6. Coral reefs- world’s most productive marine ecosystem
Tiny symbiotic algae (zooxanthellae)-convert sunlight &
nutrients into fuel for coral growth & production
Provide structural habitats for many different vertebrate
& invertebrates
7. Productivity in coral reefs - complex function of light
capture, efficient nutrient recycling, hydrodynamic
process
Unique mutualism between hermatypic corals &
photosynthetic zooxanthellae-driving force for
settlement, growth & productivity of coral reefs
8. Photosynthesis by zooxanthellae- fix large amounts of
‘carbon’; passes on to the host polyp
Mainly in the form of glycerol or glucose or alanine
9. Metabolic products are used by the polyp
Symbiotic relationship between corals &
zooxanthellae- tight recycling of nutrients back &
forth
11. Degree to which coral depends on zooxanthellae is
species specific
Corals are more productive in shallow water bodies
12. Major energy is received from sunlight
Plants, algae & bacteria-capable of capturing the
energy & produce organic matter
13. Organisms - Proximate source of energy
Termed as primary producers
14. Zooxanthellae -primary producers in corals
Belong to the genus Symbiodinium
Important algae is Symbiodinium microadriaticum
15. Zooxanthellae occupies 1-10% of biomass of living
corals
Density 1-5*10⁶ cells/cm² coral surface area
Varies with depth and season
16. Zooxanthellae translocate upto 90% of their fixed
carbon (C) directly to coral hosts
Rate at which coral deposits new skeleton (the
calcification rate) – measures production
17. Products of zooxanthellae are transferred directly to the
coral tissues
Respired, stored or released into environments
18. Corals also feeds on tiny other organisms by the mucus
produced by corals
Prey ranges from zooplankton to even small fishes
19. Productivity of coral reef depends on:
a. illumination
b. temperature conditions
20. Shallow water coral ecosystem- most productive
ecosystem of the world
Gross primary productivity-1-15gCm¯²day¯¹
21. High level of production- symbiotic algae in reef
building corals & allied invertebrates
Symbiotic algae accounts-50-70% of the total primary
production
22. Excess production from reef- 3% of total primary
production
<1% of total production is available as harvestable
form
23. Factors influencing rate of
photosynthesis by zooxanthellaea
Chief determinants- light & temperature
Photosynthesis quantified by-flux of O₂ & converted
into units of C
Availability of light for photosynthesis by
zooxanthellae in corals varies & difficult to measure
24. O₂ consumption in the light provides a measure of net
primary production
Gross primary production-net O₂ production under
illumination & O₂ release by respiration in dark
25. Coral growing areas show high primary productivity-
1500-3000gC/m²/yr
Contributed by zooxanthellae, free living algae,
phytoplankters
26. Mucus secreted by coral- due to wave action & grazing
of coral eating animals
Another source of Carbon available to plankters
27. Functional groups of coral reefs
-Primary producers
-algae, other plankters
- Planktivores
- fishes & invertebrates, including corals
Predators
-piscivores, corallivores, invertebrate eaters
-Detritivores
-bioeroders – remove coral skeletons
- scrapers – remove algae and sediments
- grazers – remove macroalgae
29. Productivity & Diversity
High Productivity
Production (kg Carbon per m2 per year)
Average Oceanic areas 0.1 kg
Rainforest 2 kg
Kelp forest 2 kg
Coral Reef 1.5-5 kg
• high productivity possible because of tight recycling of
nutrients,
photosynthetic fixation of carbon (by corals and algae)
and nitrogen (by blue-green algae)
30. Coral reef fisheries
High species diversity compared to temperate &
pelagic systems
Tropical reef support high standing crop of fishes
Highest richness of coral reef fisheries-Indo-West
Pacific especially Philippines-2177 species
31. A yield of 9 million tonnes annually is possible world wide
Fish catch with traps on reef vary between 1.37-20 tonnes/km
of coastline
Production of fish in reefs varies from 25-50 kg*10¯⁴ m¯² y¯¹
32. Number of Fish species in several
coral reef areas
Geographical area Number of Fish Species
Philippine Islands 2177
New Guinea 1700
Great Barrier Reef 1500
Seychelles Islands 880
Marshall & Marina Islands 669
Bahama Islands 507
Hawaiian Islands 448
33. Chaetodontids (butterfly fishes)- dominant species of
coral reef ecosystem
Great Barrier reef ranks first (50 species)
The Philippines ranks second
Indonesia ranks third
34. Other major inhabitants of coral
ecosystem
Sponges
Polychaete worms
Sea urchins
Star fish
Seabirds
Sea snakes
Green turtle
Gastropods
Giant clam
White tip reef shark
Banded coral shrimp
Spiny lobsters
Reef crabs
Carribean reef squid
35. More than 25,000 described species from 32 animal
phyla live in reef habitats
4 times the number of animal phyla found in tropical
rain forests
36. Play a crucial role as habitat & nursery grounds for 10-
20% of the world fishery
Intimately connected to other marine communities
such as mangrove forest, sea grass beds & open seas
37. Play significant role in the development of ecosystems-
mangrove & wetlands
Protect coastline from wave action, erosion, property
damage & loss of life
Provide livelihood for half a billion people from its
production