threats, human benefits, food web. what are corals? plants or animals? plants make their own food...
TRANSCRIPT
Threats, Human Benefits, Food Web
What are corals?
Plants or animals?Plants make their own foodAnimals depend on outside
sources for their nutritional requirements
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
Toxicity Testing LabObjectives
Measure the effect of various toxic materials on zooplankton.
Determine the LD50 (Lethal Dose 50%) for a variety of toxic materials.
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.
Lab cont. Directions
Obtain 5 petri dishes.Label these dishes as follows:
100% 10% 1% 0.1% 0% (control)
Zooxanthellae (zoo-zan-thel-a)Symbiotic
relationshipClose 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
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
Coral Bleaching
Coral Reef Food WebZooxanthellae 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
Major threats to coral reefsNaturalHurricanesTyphoonsEl NinoCoral-eating
organismsDiseases Ocean
Acidification
HumanOver-fishingCoastal
developmentSewage and
other pollutionRising global
temperaturesCarless tourism
Over-fishingFishing 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
Let’s check the zooplankton!
Coastal DevelopmentCoastal 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
Sewage and other pollutionAdds 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 Sewage pollution
Air pollution
Rising global temperaturesOne of the most global
threats to coral reef ecosystems
What causes global temperatures to rise?Burning of fossil fuelsChanges in land useReduction in forest cover
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 yearCoral reefs protect the beaches
Protect 109 countries’ coastlines
Coral reefs save livesSeveral 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
Global Climate Change and Our Life Styles
How to reduce greenhouse gas emissions:1. Conserve energy2. Buy a fuel-efficient car and drive less often3. Reduce, re-use and recycle4. Plant trees5. Reduce water use6. Choose sustainable seafood7. Educate yourself!
Get the Facts!Coral reefs are in crisis, dying at an alarming
rate worldwideAn 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.
Let’s check them again!
Questions?