The Ocean's Resources Practice Flashcards
Policies and Legal Jurisdictions of Marine Study
Several treaties regarding the ownership and exploitation of marine resources have been ratified over the last 50 years to define national controls.
The Truman Proclamation (1954): President Truman extended United States control of marine resources from the shoreline to a depth of $100\,\text{fathoms}$ ($183\,\text{m}$).
Geneva Conventions on the Law of the Sea (1958 and 1960): These conventions resulted in a treaty establishing that the country nearest to the land controls the following: - The seabed. - Seabed resources. - The water of the continental shelf.
1982 United Nations’ Draft Convention on the Law of the Sea (UNCLOS): This comprehensive treaty established specific zones of jurisdiction: - Territorial Waters: These extend seaward from the coast for $12\,\text{nautical miles}$. They are under the direct jurisdiction of the adjoining coastal nation. - Exclusive Economic Zone (EEZ): A coastal state has the authority to regulate fishing, mineral resources, pollution, and scientific research within this zone. - EEZ Extent: Extends for $200\,\text{nautical miles}$ offshore, or to the edge of the continental shelf if the shelf is broader than $200\,\text{nautical miles}$. - Global Coverage: EEZs contain approximately $40\%$ of the world's ocean. National governments control more than $40\%$ of the total ocean area. - High Seas: The remaining $60\%$ of the ocean constitutes the high seas, which are outside national EEZ control.
EEZ of the United States: The U.S. EEZ includes regions around the mainland, Alaska, and various islands and territories, including: - Midway Islands, Wake Island, Hawaii, Guam. - Kingman Reef, Palmyra Atoll, Howland and Baker Islands. - American Samoa, Puerto Rico, and the Virgin Islands.
Hydrocarbon Formation and Accumulation
Definition: Hydrocarbons are chemical compounds consisting primarily of hydrogen and carbon. Common examples include petroleum (oil) and natural gas, specifically methane ().
Origin: Hydrocarbons are derived from marine sedimentary rocks containing high concentrations of organic matter. - The source material is mostly the remains of dead plankton that did not fully decay or oxidize. - Geologic Process: Mud and plankton remains accumulated on the seafloor and were preserved by anoxic (oxygen-poor) water. - Transformation: These deposits were buried under subsequent layers of sediment. High temperatures and pressures at depth transformed the organic material into hydrocarbons.
Oil and Gas Sequence: - Oil is created first at specific temperature and pressure ranges. - At higher temperatures and pressures, oil is converted into methane gas.
Migration and Trapping: - Pressure forces oil and gas from the source rock into water-filled, porous, and permeable strata above (often sandstone). - Because oil and gas are less dense than water, they migrate upward through the pores of the rock. - Migration continues until the path is blocked by an impermeable layer (a trap).
Exploration Methods: Liquid materials in deep rocks are located using seismic reflection and refraction. - These methods identify the configuration of rock layers to determine if they have the potential to trap oil and gas. - Modern 3-D seismic technology can "visualize" signals from liquid materials at depth to improve discovery success rates.
Gas Hydrates
Nature of Deposits: Gas hydrates are unusual hydrocarbon deposits consisting of a lattice of frozen water molecules entrapping a single molecule of methane ().
Occurrence: They exist under specific pressure-temperature conditions where cold water is in contact with the seafloor. - Locations include polar sediments and the continental slope at depths between $300\,\text{m}$ to $500\,\text{m}$ below sea level.
Scale and Economic Potential: These deposits contain massive amounts of gas, but there is currently no economical method for their extraction.
Ecological Role: As hydrates break down (dissociate), they release methane, hydrogen sulfide, and ammonia into the water. - Microbes utilize these chemicals as a nutrient source. - These microbes, in turn, provide food for filter feeders surrounding "cold seeps."
Environmental Risk: Global warming may raise the temperature of bottom water sufficiently to melt deep-sea hydrate deposits. - This would release significant quantities of methane—a potent greenhouse gas—into the atmosphere.
Marine Mineral Resources: Sand and Gravel
Physical Properties: Natural aggregates of unconsolidated sediment with grain sizes larger than $0.0625\,\text{mm}$.
Accumulation: They collect in high-energy environments dominated by strong currents or waves, typically in nearshore or shallow shelf environments.
Relict Sediments: Deposits also occur across the continental shelf as relict sediments deposited in the past when sea levels were lower.
Industrial Uses: - Construction of roads and buildings (aggregate for roadbeds and foundations). - Production of concrete. - Beach nourishment/replenishment for eroding shorelines.
Environmental Impact of Mining: - Threatens benthic (bottom-dwelling) and pelagic (water column) communities. - Creates large plumes of mud/silt. - Destroys essential habitats and breeding grounds.
Deep-Sea Mineral Resources: Manganese Nodules and Cobalt
Manganese Nodules: - Composition: Approximately $20\%$ to $30\%$ manganese, $10\%$ to $20\%$ iron oxide, $1.5\%$ nickel, and less than $1\%$ of cobalt, copper, zinc, and lead. - Abundance: Extremely abundant in certain areas, such as the subtropical Pacific seafloor, where billions of kilograms of nodules exist. - Challenges: Exploitation is hindered by legal, economic, and environmental problems, as well as extreme technological costs.
Cobalt: - Location: Rich deposits are found on the sides of many seamounts and islands at depths between $1\,\text{km}$ and $2.5\,\text{km}$. - Formation: Elements form a crust on rocks through chemical reactions with seawater. - Economic Importance: Cobalt is a strategic metal used in the manufacturing of jet engines. Currently, the United States cannot produce enough cobalt to meet domestic needs.
Dark Oxygen Discovery: Recent research (Sweetman et al. 2024) has provided evidence of "dark oxygen" production at the abyssal seafloor, a discovery noted by the Scottish Association for Marine Science (SAMS).
Phosphorus Deposits
Biological Necessity: Phosphorus is required for the growth of all living organisms.
Formation: Deposits generally form on submarine terraces where coastal upwelling creates high biological productivity. - Organic wastes and remains accumulate in the sediment. - Decay releases phosphorus compounds, which precipitate specifically as phosphate nodules.
Growth Rate: Phosphate nodules grow very slowly, at a rate between $1\,\text{mm}$ and $10\,\text{mm}$ every $1,000\,\text{years}$.
Global Consumption: The current world consumption by chemical and agricultural industries is approximately $150\,\text{million tons}$ per year.
Resource Depletion: Known supplies are estimated to last only until the year $2050$.
Marine Fisheries and Industry
Fish Classification: - Pelagic fish: Live within the water column. - Groundfish: Live on or near the seafloor.
Distribution: Most of the ocean is sparsely populated due to low nutrient levels. Major fish production occurs in coastal waters and upwelling regions.
Commercial Target Factors: Targeted species typically form large schools or are present in high numbers at predictable depths/regions to ensure harvesting is economical.
Technological Aids: The industry uses sonar, scouting vessels, airplanes, and satellites to locate schools.
Drift Nets: Highly controversial because they capture all organisms too large for the mesh, resulting in high bycatch mortality. - Regulation: The 1989 United Nations’ Convention for the Prohibition of Long Drift Nets banned nets longer than $2.5\,\text{km}$. - Enforcement: Compliance is largely voluntary and difficult to enforce on the high seas.
Economic Reality: World fish production has leveled at $80\,\text{million}$ to $90\,\text{million tons}$ annually. - Currently, the expense of fishing often exceeds the profit from sales. - Many fishing industries survive only through government subsidies.
Mariculture (Marine Agriculture)
Definition: Also known as fish farming, mariculture involves raising finfish, shellfish, and algae under controlled conditions until they are ready for harvest.
Industry Statistics: - About $1$ out of every $4$ ($25\%$) fish consumed today is raised via mariculture. - Major species include Salmon (Norway is the largest producer), oysters, and mussels.
Economic Viability Criteria: To be profitable, a species must be: - Marketable. - Inexpensive to grow. - Trophically efficient. - Reach marketable size within $1$ to $2\,\text{years}$. - Disease resistant.
United States Aquaculture (2018 Data): - Total production value: . - Top marine species by value: Oysters (), Clams (), and Atlantic salmon (). - Aquaculture accounts for $21\%$ of total U.S. seafood production.
Questions and Discussion
Resource Identification: Question 1 asks to name resources that can be used and exploited from the world's oceans. These include hydrocarbons (oil/gas), gas hydrates, sand, gravel, manganese nodules, cobalt, phosphorus, finfish, and shellfish.
Audience Polling: Throughout the lecture, students are directed to join "QuestionTime" via the Vevox app (ID: 182-245-881) for interactive segments.