1. Threats, Human Benefits, Food Web
Coral Reefs
Threats, Human Benefits, Food Web

2. What are corals? Plants or animals? Plants make their own food
Animals depend on outside sources for their nutritional requirements

3. They’re animals!
Coral animals take advantage of both forms of nutrition by hosting plant-like algae (protists) in their tissues.
The majority of the coral’s energy needs are provided by tiny algae called zooxanthellae
Zooxanthellae live inside the coral and produce food using the sun’s energy from carbon dioxide and water

4. Toxicity Testing Lab Objectives
Measure the effect of various toxic materials on zooplankton.
Determine the LD50 (Lethal Dose 50%) for a variety of toxic materials.

5. Lab cont.
Introduction
We handle many materials daily that are toxic. We are often unaware of the degree to which they are toxic. In this laboratory we will look at water solutions of several household materials and determine their toxicity to zooplankton.
Measuring toxicity requires a standard method of comparison. A typical method is to determine the concentration of a toxic material that causes 50% mortality in a population of test animals. This is called an LD50 (Lethal Dose 50%) test of toxicity. For a variety of reasons, different animals respond differently to the same toxin. Some animals may be very sensitive to a toxin, whereas others are relatively resistant to its effects. Because species of animals vary, it is important to understand that what is toxic to zooplankton may not necessarily be toxic to other kinds of animals to the same extent.
Many household items that we deal with on a regular basis are toxic materials, but we don’t usually think of them as being toxic. It should be instructive to examine several such materials to determine their toxicity.

6. Lab cont. Directions Obtain 5 petri dishes.
Label these dishes as follows:
100%
10% 1%
0.1%
0% (control)

7. Zooxanthellae (zoo-zan-thel-a)
Symbiotic relationship
Close relationship between two or more organisms
Mutualism: benefiting both partners
Corals animals and zooxanthellae
Sensitive to high light, variations in the concentrations of salt and especially to high temperatures
Use sunlight for photosynthesis
If sea temperature is too high, zooxanthellae leave, causing the corals to appear brilliant white

8. What is coral bleaching?
Bleaching is what happens to corals when sea temperatures are too warm for zooxanthellae to live
Zooxanthellae gives coral it’s color, when there is more zooxanthellae, the corals are green/brown

9. Coral Bleaching

10. Coral Reef Food Web
Zooxanthellae provide corals with vital nutrients produced through photosynthesis
Plant life in the sea is composed of microscopic planktonic algae that comprise the base of the entire marine food chain
The wealth of plant life supports quantities of tiny drifting animals (zooplankton) which feel upon drifting plants, and are ultimately swept across coral reefs
Coral polyps feed on zooplankton suspended in the flow of sea water
Zooplankton is a substantial part of the coral reef food chain

11. Major threats to coral reefs
Natural
Hurricanes
Typhoons
El Nino
Coral-eating organisms
Diseases
Ocean Acidification
Human
Over-fishing
Coastal development
Sewage and other pollution
Rising global temperatures
Carless tourism

12. Over-fishing
Fishing selectively takes larger, predatory fish off the reef causing explosions of smaller herbivorous fish
When larger fish become scarce, the herbivorous fish are then targeted by fishermen
Without herbivores, seaweeds can overgrow the corals and smother them
Destructive fishing practices include using cyanide to stun fish for capture for the marine aquarium and live fish trades and blast fishing to kill fish for food
Fishing methods are not species-specific, so many organisms are killed in the process and habitats that took thousands of years to build are destroyed

13. Let’s check the zooplankton!

14. Coastal Development
Coastal construction often removes mangroves and seagrass beds, which takes away the sediment barrier
Excess sediments cover corals, blocking light necessary for their symbiotic zooxanthellae
Under natural conditions, corals are able to out-compete seaweeds because of the low nutrient content in tropical waters
When outside nutrients are added, faster growing seaweeds can take over and smother corals

15. Sewage and other pollution
Adds unnatural and potentially harmful substances to the reef systems including nutrients, pathogens and trash
Implicated in the apparent surge in coral diseases, especially in the Caribbean
Garbage pollution
Air pollution
Sewage pollution

16. Rising global temperatures
One of the most global threats to coral reef ecosystems
What causes global temperatures to rise?
Burning of fossil fuels
Changes in land use
Reduction in forest cover

17. Why Care about Coral Reefs?
Healthy Coral Reefs = A Healthy World
Support 25% of all marine life
Provide habitat, income, food, protection, medicine
Animals that live nowhere else
Home to more than 4,000 species of fish, 700 species of coral and thousands of other plant and animal life.
Scientists estimate that, in total, more than one million species of plants and animals are associated with coral reef ecosystems
Millions of humans depend on coral reefs
Coral reefs provide economic goods and ecosystem services worth about $375 billion each year
Coral reefs protect the beaches

18. Protect 109 countries’ coastlines Coral reefs save lives
Several important drugs have already been developed from chemicals found in coral reef organisms
Cardiovascular disease
Ulcers
Leukemia
Skin cancer
More than half of all new cancer drug research focus on marine organisms

19. Global Climate Change and Our Life Styles
How to reduce greenhouse gas emissions:
Conserve energy
Buy a fuel-efficient car and drive less often
Reduce, re-use and recycle
Plant trees
Reduce water use
Choose sustainable seafood
Educate yourself!

20. Get the Facts!
Coral reefs are in crisis, dying at an alarming rate worldwide
An estimated 25% of coral reefs already disappeared and an estimated two-thirds of all oral reefs are at risk today
An estimated 88% of the reefs in Southeast Asia, the most species rich reefs on earth, are at risk
Since 1975, more than 90% of the reefs in the Florida Keys have lost their living coral cover
The most important fact:
There are solutions to this crisis.

21. Let’s check them again!

22. Questions?