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Human impacts on marine ecosystems (Pollution (Endocrine disruptors (PCB,…
Human impacts on marine ecosystems
Invasives
Non-natives that may or may not do harm.
Lionfish
(no natural predators, voracious predator themselves, fast reproduction).
Introduced
via
Ballast/ boat hull
Pet/aquarium trade
Aquaculture
Deliberate release
Zebra mussel
Singapore
should have most invasive species in the world >250 species. (Introduced from ships)
SG
only has 6 invasive species from ships
San Francisco
bay >150 invasive species, difficult to find native species
Comb jelly
European oyster
Shore crabs
Algal invasives
Habitat Destruction
Coastal Development
50% of population living within 100km of coast
seawalls
Prevent erosion of reclaimed land
Protection against storm surge
Sea level rise
SG 20% coastline with seawalls
HK 9%
Mangroves
Turned into prawn farms
Biggest cause of destruction? Agriculture creep, reclaiming mangrove 80%
Damming of rivers
no release of sediments to mangroves, ultimate loss of coastal habitat.
Pollution
Endocrine disruptors
PCB, PBDE (fire retardants), POP (persistent organic pollutant)
Sediments
Light attenuation
Smothering of benthos
Not a good substrate
Visibility
Plastics
Choking
Entanglement
Micro/macro plastics
LAFG (lost and abandoned fishing gear), ghost fishing.
Mostly come from land ~80%, shipping industry
Noise
Ships (150 – 190db)
Sonars (230db)
Impairs health and physiological development
Eutrophication
Sewage
• Agriculture
• Harmful algal bloom (poison, bioaccumulation in marine animals eg shellfish
• Biomagnification in higher trophic level
• Dead zones
• Macroalgae growth
Light
Affects coral spawning which requires moonlight
Oil
-Spills
-Natural seeps
-Run off
Radiation
Toxics
Waste products of minerals exploitation is dumped in intertidal or near-shore.
Thermal
Pumps warm water into ocean
Exploitation
Abiotic
Non renewable resource
eg oil, natural gas, sand/gravel (dredging), tin, salt, metallic nodules
Dredging
Releases toxic, nutrients
Destroys habitat
Biotic
Dynamite/cynanide fishing
All other methods of fishing
Bycatch
Bottom trawling
Overfishing globally
Technology creep
Limiting time at sea
Climate Change
Range Shift
Leading edge: introduction and expansion into new habitat
Limited by light and temperature
Temperature affects conductivity of echolocating organism
Range shift in terms of geography and depth.
Increase in sea level, some species can move upwards (range shift) and settle on seawalls etc
Trailing edge: localised extinction, species no longer found in its original habitat
Ocean warming
Reduction in O2 in ocean
Sea level rise (thermal expansion).
Melting of polar ice, ice shelf (already floating in water, volume contributed to sea level rise is little).
Melting of terrestrial glaciers, ice sheet contribute significantly to sea level rise.
Permafrost methane underneath ice sheet and glaciers. Melting releases methane!
Coral bleaching
Physio-thermal regulation (energetically intensive, diversion of resource away from reproduction etc)
Coastal squeeze of mangroves
Habitat Loss
Via flooding, generates more sediments
Reduction in terrestrial land, especially islands
GLOBAL WARMING
Increase in CO2 from combustion
Thinning of ozone layer from release of CFC, HFC
Ocean Acidfication
Unrelated process (erosion and calcification). Separate processes.
Calcification (intracellular)
Erosion (environment)
Photosynthesising organism benefit from ocean acidification
eg Seagrass (need CO2,increase in productivity…)
-phytoplankton (dinoflagellates, coccolithophores) Different groups different responses
Other stuff
Blast fishing and cyanide fishing
Conservation effects:
Restocking giant clams
Enhancing biodiversity on seawalls
International Coastal Cleanup
REUs
Nature Reserves