1. The Impacts of Humans on the Marine Environment
Chapter 18
The Impacts of Humans on the Marine Environment

2. Modification and Destruction of Habitats
Most habitat destruction occurs close to shore (due to the greater number of humans nearby)
Much of this destruction results from unplanned or poorly planned development
This destruction is more pronounced in developing countries, but it is not restricted to these areas

3. Coral Reefs
Approximately one-fourth of all coral reefs have already been lost or are at risk
Pollution from sewage, sedimentation, and rising temperatures have caused some of this damage
Corals are also lost due to collection for the aquarium trade and for sale as souvenirs

4. Coral Reefs
One-third of reef-building corals currently face extinction
Goal is to protect reef and other ecosystem’s biodiversity

5. Coral mining for souvenirs, marine aquaria, and construction material

6. Bleached coral have lost zooanthellae and may die
Bleached coral have lost zooanthellae and may die. Stressors like hot water,
pollution, and disease can cause bleaching.

7. Problems Caused by Trawling
Trawl nets are a major threat to subtidal habitats
These nets, which drag along the bottom, cause resuspension of sediments which can kill suspension feeders
The trawls can also break off attached organisms

8. Pollution
Pollution is described as the human introduction of a substance that reduces the quality of the environment
Some pollutants are liberated by human activities such as the release of heavy metals from mining
Most pollutants come from land-based substances

9. Sources of Pollution 1. Fertilizers 2. Sewage 3. Oil
4. Persistent toxic substances

10. Sources of Pollution Fertilizers
Land-based fertilizers wash into streams and rivers and are carried into coastal waters
This influx of nutrients causes phytoplankton numbers to rise rapidly (called a “______”) resulting in eutrophification
These blooms can cause several problems including reducing the amount of light available to organisms attached to the bottom such as seagrasses and corals

11. Sources of Pollution Fertilizers
Other problems with these blooms occur after the phytoplankton die
As cells die and drop to the bottom, the influx of massive amounts of organic matter means decomposing bacteria begin to work
As a result of this breakdown, oxygen is consumed and anoxic conditions may occur

12. Sources of Pollution
Sewage in a marsh and sources of oil.

13. Sources of Pollution Sewage
Domestic sewage comes from homes and city buildings as well as stormwater runoff
Industrial sewage comes from factories, etc. and may contain a variety of substances
This sewage may contain disease-causing organisms
It may also contain heavy metals or other toxic substances even if treated

14. Sources of Pollution Oil
Organisms can accumulate components, many of which are toxic
These components can affect reproduction, growth, development and behavior
Organisms may also die if their feathers or fur is coated with oil
Estuarine organisms, seagrasses and corals are also at risk if coated with oil

15. Sources of Pollution Oil-coated coot during Exxon Valdez spill
Sources of Pollution Oil-coated coot during Exxon Valdez spill. New text has a loggerhead turtle being cleaned after Deepwater Horizon spill by British Petroleum

16. Sources of Pollution Persistent Toxic Substances
Examples are chlorinated hydrocarbons (pesticides) and polychlorinated biphenyls (PCB’s; used in transformers and products like plastic and paint ) and heavy metals (from many industrial sources)
They enter as runoff and are passed from prey to predator. As predators eat more prey, they continue to accumulate in their tissues (known as biological ___). Some fish may not be safe to eat due to magnified levels.
Chlorinated hydrocarbons affect seabird reproduction, PCBs cause cancer and birth defects, heavy metals cause brain, kidney and liver damage, and birth defects

17. Other Dangers to the Marine Environment
Solid wastes = trash you see washed up on beach that can entangle animals or be ingested by mammals
Thermal pollution due to using seawater as a coolant in power plants
Saline brines from desalination plants

18. Threatened and Endangered Species
Organisms normally adapt to changing conditions through a process known as natural selection
If they cannot adapt, they go extinct
Human-induced extinctions can be called exterminations

19. Threatened and Endangered Species
Threatened status – numbers of a species are low and a species is in danger of becoming endangered
Endangered status – species is in immediate danger of extinction

20. Threatened and Endangered Species

21. Threatened and Endangered Species
Example of an Extinction by overhunting
Stellar’s sea cow
The species became known to science in 1741; the last known live individual was taken in 1768

22. Overhunting the stellar sea cow

23. Threatened and Endangered Species
Examples of other species imperiled today:
Whales – due to overfishing
Giant clams – for food and shells by collectors
Cone shells – for shells by collectors
Sharks – due to overfishing
Sea turtles – for food, jewelry, and shells

24. Conservation Methods Used to Protect Marine Organisms and Habitats
Efforts to keep development at sustainable levels
These are local, national and international efforts
Fisheries management
Marine protected areas
Habitat restoration
Artificial reefs

25. Restoration– Transplanting giant kelp plants

26. Building artificial reefs of concrete blocks

27. Gulf Coast Read Eye on Science, Pg 411 and discuss
TPWD Power Point presentation