THREATS TO MARINE
SK.UMME SA
MFK 1710,
AEM.

• The ocean was viewed as a boundless reservoir of productivity with
unlimited capacity to assimilate wastes.
• A Productive ecosystem is characterized by High degree of biological
diversity .
• Species has a well defined role to play.
• Provide numerous pathways for energy of a system to flow.
• The resources of the sea have been over harvested by human thereby
threatening marine biodiversity.

• Threats to marine biodiversity have widespread social, economic, and
biological consequences, the combination of which could threatend our
own existence, including:
• Economic losses through unemployment and reduced productivity
• Dramatic reductions in the numbers of many popular edible fish and
shellfish
• Threatned species that might be useful in developing new medicines
• Reduced ability of ecosystems to respond to disaster, both natural (floods)
and man-made (pollution)
• Accelerated global climate change
• Social and political instability

MAJOR THREATS
• Over exploitation - recreational and commercial
• Pollution
• Habitat destruction and fragmentation
• Non-native species invasions
• Global climate change

INTRODUCTION OF ALIEN SPECIES
• Invasive species can dramatically change the structure and function of
marine ecosystems by changing biodiversity and eliminating vital
components of the food chain.
• These species are harmful to native biodiversity in a number of ways.
• For example, as competitors, predators, parasites, or by spreading disease.
• Ships use water as ballast to adjust their position in the water to improve
their maneuverability and stability.
• Mariners typically pump water into ballast tanks at one port and discharge
it when taking on cargo at another port

• Mariners have unintentionally transplanted locally native marine species to
new areas with the ballast water.
• The arrival of an invasive jellyfishlike organism, Mnemiopsis leidyi, led to
a major ecological “regime change” in the Black Sea, Many other species
have been introduced as planktonic larvae in ballast water.
• There are many alien species: Many seaweeds like red algae (Kappaphycus
striatum), zebra mussel (Dreisssena polymorpha), lion fish (Aquarium fish)

CLIMATE CHANGE
• Global warming will cause sea level rise.
• As a result higher temperature decreases the ability of water to dissolve
oxygen.
• Humans, however, have been increasing the amount of CO 2 in the
atmosphere by burning enormous amount of fossil fuels.
• Loggerhead Turtle nests in Florida have already producing 90% females
owing to high temperatures, and if warming raises temperatures by an
additional 1º C or more, no males will be produced there.
• Coral reefs require particular environmental conditions for growth and
water temperatures from 23–29 °C are optimal for growth.

• Increasing temperature too much can cause the coral polyps to expel the
zooxanthellae and lead to coral bleaching where the zooxanthellae are
expelled from the coral by the polyps.
• Coastal power plants use seawater for cooling and discharge the warmed
water at the coast.
• Warming is bad for polar communities, the Arctic pack ice has been
getting thinner at a rate that if maintained will result in the Arctic becoming
ice free in a few decades, and with its disappearance will go polar bears,
walruses and many of the other Arctic species.

POLLUTION
• Pollutants in the air,water,and soil can affect organisms in many ways,
from altering the rate of plant growth to changing reproduction patterns,in
certain extreme situations,leading to extinction.
• Coral reefs can be damaged by a variety of pollutants that are produced by
a variety of sources.

• Human sewage, often untreated,can add nutrients,microorganisms and
other pollutants for coral reefs depletion.
• Mass mortality of fish or other marine organisms has been reported from
different regions caused by the release by industrial wastes.
• Animals can be poisoned or suffer internal damage from ingesting oil so
marine animals become sleepy and drown.

• One of the most prevalent side effects of an oil spill is hypothermia.
• Once the oil drifts into the water, it creates a sticky substances called
‘mousse’.
• Oil spills affect marine life like filter feeders by concentrating the flesh of
the animals.
• Oil spills are especially harmful if they occur during coral spawning because
the oil can kill eggs and spawn.

There are three main types of inputs of pollution into the ocean
• Direct discharge of waste into the oceans
•Runoff into the waters due to rain
•Pollutants that are released from the atmosphere
Sources of oil pollution are :
•Tankers.
•Ballast water
•Bilage washings.
•Factories etc

• Marine pollution includes a range of threats including from land-based
sources
– Oil spills,
– Untreated sewage,
– Heavy siltation,
– Eutrophication (nutrient enrichment),
– Persistent organic pollutants (POP’s),
– Heavy metals from mine tailings and other sources,
– Acidification,
– Radioactive substances,
– Marine litter.

OIL SPILLS

UNTREATED
SEWAGE

EUTROPHICATION

marine litter

ACIDIFICATIO
N

OVER EXPLOITATION
• Overexploitation can lead to resource depletion and put a number of
threatened and endangered species at risk for extinction.
• A greater variety of species at a higher trophic level is exploited in the sea
than on land: humans exploit over 400 species as food resources from the
marine environment.
• Worldwide, fishing fleets are two to three times as large as needed to take
present day catches of fish and other marine species
• The use of modern techniques to facilitate harvesting, transport and storage
has accelerated the over exploitation.

• Total of almost 80% of the world’s fisheries are fully to over
exploited,depleted, or in a state of collapse.
• Recently, a study showed that 29% of fish and seafood species have
collapsed (i.e. their catch has declined by 90%) and are projected to
collapse within by 2048, unless immediate action is taken.
• Worldwide about 90% of the stocks of large predatory fish stocks are
already collapsed. Target species are generally the most impacted by over
exploitation.
• Threatening many other species, particularly large sized fishes such as
tunas,sword fish, and sharks.

• Direct and Indirect effects of overfishing
• Growth and recruitment overfishing
• Habitat loss – benthic trawling
• Ghost fishing
• Trophic cascading effects

HABITAT DESTRUCTION
• Loss of habitat is the major reason why aquatic biodiversity is declining.
• Describes the emergences of discontinuities (fragmentation) or the loss
(destruction) of the environment inhabited by an organism.
• Approximately 20% of the world’s coral reefs were lost
• 20% degraded in the last several decades of the twentieth century
• 35% of mangrove area was lost during this time.
• Extinction is a terrible waste of life and a loss of potential solutions to
future problems such as possible cures to disease and solutions for
survival in a changing world.

• For ex: Rising temperatures, rising sea levels, and other trends will have an
effect on the world’s 6 species of sea turtles.
• coral reef fish is with cyanide a poison.
• Mangrove forests are routinely being cleared, with huge impacts on
biodiversity.
• Healthy mangrove forests provide a critical habitat for many species in
intertidal and estuarine areas and are key to a healthy marine environment.

Threats to Mangroves
• Tree felling for fuel wood and wood products
 Grazing by cattle
 Reclamation for agriculture and aquaculture
 Urban development and human settlements
 Industrialization, Port and Harbour development
 Mining Siltation and Sedimentation

CONCLUSION
• Human attention rightly focuses on the decline of biodiversity
on land, but this should not happen at the expense of the
oceans attention to marine biodiversity
• Preserving marine biodiversity for the sake of knowledge
itself is important.
• Biodiversity is declining very rapidly and efforts to stop the
declined must be intensified .
• There needs to be more public support in order to conserve.

THANK
YOU