deep sea pt.2 Flashcards
7 reasons we should care about the deep sea
- Largest ecosystem
- substantial biodiversity
- Ecosystem services – geochemical cycling
- Global ocean conveyor belt + upwelling
- Scientific interest – gradual long term large scale changes
- Vulnerable fauna
- Rapidly increasing anthro impacts
Ecological characteristics of the DS
- Low productivity
- Highly dependent on surface productivity
- Low energy + low disturbance env -> lower resilience to changes
- Bottom of the bucket
- High biodiversity per unit area
- Large habitat areas
- Broad species distributions
- Unkown and unexplored
- Lack of interest
- Largely in international waters
Life history characteristics of deep sea organisms and what do they mean as a whole
- Long lived
- Slow growing
- Late maturity
- Slow biological rates
- Adapted to low disturbance
MEANS: - Faster crashes of fisheries
- Longer recovery times
- Higher extinction rates
**DS more vulnerable to anthro impacts than shallow water
3 main anthropogenic impacts on deep sea
- disposal
- exploitation
- Ocean acidification & climate change
3 types of anthropogenic disposal that can impact the deep sea
Indirect Disposal
Direct Disposal
CO₂ Sequestration in the Deep Sea
how can indirect disposal impact the deep sea
- enters through shipments, litter, accidental loss
- e.g. plastics, metals, wood, and organic waste.
- Bioaccumulation of harmful substances like PCBs, DDTs, and methyl mercury affects marine life
- Diseased animals disposed overboard - organic enrichment, disrupting natural ecosystems.
- Shipwrecks - introduce toxic materials into the environment
how can direct disposal impact the deep sea
Industrial & hazardous waste: Includes radionuclides, radioactive waste, chemicals, pharmaceuticals, sewage sludge, drilling and mining tailings
- all of which contain toxic compounds harmful to marine ecosystems
how can CO₂ Sequestration in the Deep Sea impact the deep sea
- Some proposals suggest storing excess CO₂ in the deep sea to reduce atmospheric carbon levels.
- this can decrease pH, affect marine respiration, and impact marine Carbon Dioxide Removal (mCDR) processes, altering deep-sea chemistry and ecosystems
explain the impact of anthropogenic exploitation on the deep sea
- Overfishing of deep-sea species - trawling damages habitats e.g. coral reefs and seamounts
- Deep-Sea Mining:
-polymetallic sulfides (seamounts & hydrothermal vents)
-cobalt-rich manganese crusts (seamounts)
-manganese nodules (abyssal plains)
-metalliferous muds containing gold, cobalt, copper, silver, and other rare metals (“critical minerals”)
*Large areas of the seafloor have already been leased for mining e.g. Papua New Guinea - Oil & Gas Extraction:
-occurs along continental margins, cold seeps, and deep-sea coral habitats.
-Drilling muds & cuttings introduce chemical pollutants, bury organisms, and cause organic enrichment
-Methane hydrates (solid methane deposits) are being considered for extraction but pose major risk
what are the problems with deep sea mining
- Habitat destruction: disrupts hydrothermal vents, seamounts, and deep-sea coral ecosystems
- Sediment plumes: Mining generates large plumes of suspended sediment that spread downstream, affecting marine communities
- No recovery: Once deep-sea habitats are damaged, recovery is extremely slow or impossible
Key Issues with Methane Hydrates
- unstable - could release large amounts of methane
- Seep ecosystems—some deep-sea species are endemic to methane hydrate environments and may be disrupted by extraction
- Climate risk: Uncontrolled methane release could contribute to global warming
explain the impact of anthropogenic induced ocean acidification on the deep sea
OA
- Aragonite (form of calcium carbonate) dissolves below a certain depth (aragonite saturation horizon - ASH) which is becoming shallower - making it harder for corals and marine organisms (DS corals) to build skeletons at deeper depths
- effects primary prod
explain the impact of anthropogenic induced climate change on the deep sea
- Deep-water formation areas are warming the fastest - alters ocean currents and heat distribution.
- Deep-water circulation is affected by stratification (when warm, less dense water prevents deep mixing).
- Disruptions in thermohaline circulation can change global climate pattern
what are the synergistic effects of ocean acidification and climate change
occurring simultaneously, worsening their individual impacts
- deep-sea waste disposal was considered the biggest human impact on DS - Now, OA and CC
