Chapter 18 The Impacts of Humans on the Marine Environment.

Chapter 18Chapter 18

The Impacts of Humans on The Impacts of Humans on the Marine Environmentthe Marine Environment

Modification and Modification and Destruction of HabitatsDestruction of Habitats

• Most habitat destruction occurs close to Most habitat destruction occurs close to shore (due to the greater number of shore (due to the greater number of humans nearby)humans nearby)

• Much of this destruction results from Much of this destruction results from unplanned or poorly planned unplanned or poorly planned developmentdevelopment

• This destruction is more pronounced in This destruction is more pronounced in developing countries, but it is not developing countries, but it is not restricted to these areasrestricted to these areas

Coral ReefsCoral Reefs

• Approximately one-fourth of all coral Approximately one-fourth of all coral reefs have already been lost or are at reefs have already been lost or are at riskrisk

• Pollution from sewage, sedimentation, Pollution from sewage, sedimentation, and rising temperatures have caused and rising temperatures have caused some of this damagesome of this damage

• Corals are also lost due to collection for Corals are also lost due to collection for the aquarium trade and for sale as the aquarium trade and for sale as souvenirssouvenirs

Coral ReefsCoral Reefs

• One-third of reef-building corals One-third of reef-building corals currently face extinctioncurrently face extinction

• Goal is to protect reef and other Goal is to protect reef and other ecosystem’s biodiversityecosystem’s biodiversity

Coral mining for souvenirs, marine aquaria, and construction material

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

Problems Caused by Problems Caused by TrawlingTrawling

• Trawl nets are a major threat to Trawl nets are a major threat to subtidal habitatssubtidal habitats

• These nets, which drag along the These nets, which drag along the bottom, cause resuspension of bottom, cause resuspension of sediments which can kill suspension sediments which can kill suspension feedersfeeders

• The trawls can also break off The trawls can also break off attached organismsattached organisms

PollutionPollution

• Pollution is described as the human Pollution is described as the human introduction of a substance that introduction of a substance that reduces the quality of the environmentreduces the quality of the environment

• Some pollutants are liberated by Some pollutants are liberated by human activities such as the release of human activities such as the release of heavy metals from miningheavy metals from mining

• Most pollutants come from land-based Most pollutants come from land-based substancessubstances

Sources of PollutionSources of Pollution

1. Fertilizers1. Fertilizers

2. Sewage2. Sewage

3. Oil3. Oil

4. Persistent toxic substances4. Persistent toxic substances


• FertilizersFertilizers– Land-based fertilizers wash into streams and Land-based fertilizers wash into streams and

rivers and are carried into coastal watersrivers and are carried into coastal waters– This influx of nutrients causes phytoplankton This influx of nutrients causes phytoplankton

numbers to rise rapidly (called a “______”) numbers to rise rapidly (called a “______”) resulting in eutrophificationresulting in eutrophification

– These blooms can cause several problems These blooms can cause several problems including reducing the amount of light including reducing the amount of light available to organisms attached to the bottom available to organisms attached to the bottom such as seagrasses and coralssuch as seagrasses and corals


• FertilizersFertilizers– Other problems with these blooms occur Other problems with these blooms occur

after the phytoplankton dieafter the phytoplankton die– As cells die and drop to the bottom, the As cells die and drop to the bottom, the

influx of massive amounts of organic influx of massive amounts of organic matter means decomposing bacteria begin matter means decomposing bacteria begin to workto work

– As a result of this breakdown, oxygen is As a result of this breakdown, oxygen is consumed and anoxic conditions may occurconsumed and anoxic conditions may occur

Sources of PollutionSources of PollutionSewage in a marsh and sources of oil.


• SewageSewage– Domestic sewage comes from homes and Domestic sewage comes from homes and

city buildings as well as stormwater runoffcity buildings as well as stormwater runoff– Industrial sewage comes from factories, etc. Industrial sewage comes from factories, etc.

and may contain a variety of substancesand may contain a variety of substances– This sewage may contain disease-causing This sewage may contain disease-causing

organismsorganisms– It may also contain heavy metals or other It may also contain heavy metals or other

toxic substances even if treatedtoxic substances even if treated


• OilOil– Organisms can accumulate components, many Organisms can accumulate components, many

of which are toxicof which are toxic– These components can affect reproduction, These components can affect reproduction,

growth, development and behaviorgrowth, development and behavior– Organisms may also die if their feathers or fur Organisms may also die if their feathers or fur

is coated with oilis coated with oil– Estuarine organisms, seagrasses and corals are Estuarine organisms, seagrasses and corals are

also at risk if coated with oilalso at risk if coated with oil

Sources of PollutionSources of PollutionOil-coated coot during Oil-coated coot during Exxon Valdez Exxon Valdez spill. New text has a spill. New text has a

loggerhead turtle being cleaned after loggerhead turtle being cleaned after Deepwater Horizon Deepwater Horizon spill spill by British Petroleum by British Petroleum

Sources of PollutionSources of Pollution• Persistent Toxic SubstancesPersistent Toxic Substances

– Examples are chlorinated hydrocarbons (pesticides) and Examples are chlorinated hydrocarbons (pesticides) and polychlorinated biphenyls (PCB’s; used in transformers polychlorinated biphenyls (PCB’s; used in transformers and products like plastic and paint ) and heavy metals and products like plastic and paint ) and heavy metals (from many industrial sources)(from many industrial sources)

– They enter as runoff and are passed from prey to They enter as runoff and are passed from prey to predator. As predators eat more prey, they continue to predator. As predators eat more prey, they continue to accumulate in their tissues (known as biological ___). accumulate in their tissues (known as biological ___). Some fish may not be safe to eat due to magnified levels.Some fish may not be safe to eat due to magnified levels.

– Chlorinated hydrocarbons affect seabird reproduction, Chlorinated hydrocarbons affect seabird reproduction, PCBs cause cancer and birth defects, heavy metals cause PCBs cause cancer and birth defects, heavy metals cause brain, kidney and liver damage, and birth defectsbrain, kidney and liver damage, and birth defects

Other Dangers to the Marine Other Dangers to the Marine EnvironmentEnvironment

• Solid wastes = trash you see washed Solid wastes = trash you see washed up on beach that can entangle up on beach that can entangle animals or be ingested by mammalsanimals or be ingested by mammals

• Thermal pollution due to using Thermal pollution due to using seawater as a coolant in power seawater as a coolant in power plantsplants

• Saline brines from desalination plantsSaline brines from desalination plants

Threatened and Endangered Threatened and Endangered SpeciesSpecies

• Organisms normally adapt to Organisms normally adapt to changing conditions through a changing conditions through a process known as natural selectionprocess known as natural selection

• If they cannot adapt, they go extinctIf they cannot adapt, they go extinct

• Human-induced extinctions can be Human-induced extinctions can be called exterminationscalled exterminations


• Threatened status – numbers of a Threatened status – numbers of a species are low and a species is in species are low and a species is in danger of becoming endangereddanger of becoming endangered

• Endangered status – species is in Endangered status – species is in immediate danger of extinctionimmediate danger of extinction


• Example of an Extinction by Example of an Extinction by overhuntingoverhunting

• Stellar’s sea cowStellar’s sea cow

• The species became known to The species became known to science in 1741; the last known live science in 1741; the last known live individual was taken in 1768individual was taken in 1768

Overhunting the stellar sea cow


• Examples of other species imperiled Examples of other species imperiled today:today:– Whales – due to overfishingWhales – due to overfishing– Giant clams – for food and shells by Giant clams – for food and shells by

collectorscollectors– Cone shells – for shells by collectorsCone shells – for shells by collectors– Sharks – due to overfishingSharks – due to overfishing– Sea turtles – for food, jewelry, and shellsSea turtles – for food, jewelry, and shells

Conservation Methods Used Conservation Methods Used to Protect Marine Organisms to Protect Marine Organisms

and Habitatsand Habitats• Efforts to keep development at sustainable Efforts to keep development at sustainable

levelslevels

• These are local, national and international These are local, national and international effortsefforts

• Fisheries managementFisheries management

• Marine protected areasMarine protected areas

• Habitat restorationHabitat restoration

• Artificial reefsArtificial reefs

Restoration– Transplanting giant kelp plants

Building artificial reefs of concrete blocks

Gulf CoastGulf Coast

• Read Eye on Science, Pg 411 and Read Eye on Science, Pg 411 and discussdiscuss

• TPWD Power Point presentationTPWD Power Point presentation

• http://www.youtube.com/watch?http://www.youtube.com/watch?v=7c6FnXES71wv=7c6FnXES71w

Chapter 18 The Impacts of Humans on the Marine Environment.

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