4. Water and Aquatic Food Production Systems and Societies

What are the main stores and flows in the hydrological cycle?

• Stores: oceans, lakes, groundwater, ice caps, soil moisture, and atmosphere.

• Flows: precipitation, evaporation, transpiration, condensation, infiltration, percolation, and runoff.

What are human impacts on the hydrological cycle?

Human activities like deforestation, urbanization, dam construction, and groundwater extraction disrupt water flows, alter storage, and can reduce water quality and availability.

What is the difference between surface water and groundwater, and why are they important?

• Surface water: water in rivers, lakes, and reservoirs.

• Groundwater: water stored in aquifers below Earth's surface.
  Both are critical for drinking water, agriculture, and industrial use.

What are some strategies to increase freshwater availability?

Strategies include desalination, water recycling, rainwater harvesting, building reservoirs, and improving irrigation efficiency.

What are factors that affect access to freshwater?

Climate, geography, infrastructure, population density, economic development, and political stability all influence access to freshwater resources.

What are the main types of water pollution, and how do they differ?

• Point-source pollution: comes from a single, identifiable source (e.g., a factory pipe).

• Non-point source pollution: diffuse sources (e.g., agricultural runoff).
  Pollutants include pathogens, nutrients, heavy metals, plastics, and chemicals.

How can water pollution be managed?

By reducing pollutant inputs (e.g. reducing fertilizer use), improving wastewater treatment, enacting environmental laws, promoting sustainable agriculture, and public education.

What are fisheries, and why are they important?

Fisheries are areas where fish are caught for commercial, recreational, or subsistence purposes. They provide food, employment, and economic benefits globally.

What are the environmental impacts of unsustainable fishing practices?

Overfishing, bycatch, habitat destruction (e.g., trawling), and reduced biodiversity, which threaten marine ecosystems and food security.

What are some sustainable fishing methods?

Quotas, no-fishing zones, selective fishing gear, seasonal restrictions, and aquaculture (when done responsibly) can help maintain fish populations.

What is aquaculture, and what are its pros and cons?

• Aquaculture is the farming of fish, shellfish, or aquatic plants.

• Pros: boosts food supply, reduces pressure on wild stocks.

• Cons: disease spread, water pollution, habitat degradation, and use of wild fish for feed.

What is maximum sustainable yield (MSY) in fisheries management?

MSY is the largest yield (catch) that can be taken from a species’ stock over an indefinite period without causing population decline.

How can international cooperation support sustainable fishing?

Through global treaties, agreements (e.g. UNCLOS), data sharing, joint monitoring, and enforcement to regulate fishing beyond national jurisdictions.

What is the role of marine protected areas (MPAs) in conservation?

MPAs conserve biodiversity, allow fish stocks to recover, protect critical habitats, and support ecosystem resilience by limiting or banning certain activities.

How does climate change affect water resources and aquatic systems?

It alters precipitation patterns, accelerates glacial melt, causes sea level rise, increases water temperature, and disrupts aquatic food webs and fisheries.

What are aquifers, and why are they important in the context of water resources?

Aquifers are underground layers of permeable rock or sediment that hold water, known as groundwater. They are vital sources of freshwater for drinking, irrigation, and industry.
Over-extraction can lead to issues such as groundwater depletion, subsidence, and saltwater intrusion in coastal areas.

How does eutrophication affect freshwater systems?

Eutrophication, caused by excess nutrients (usually from agriculture), leads to algal blooms, oxygen depletion, fish kills, and reduced biodiversity in water bodies.

What are some examples of conflicts over water use?

• Nile River conflict (Egypt vs. Ethiopia) over dam construction.

• Aral Sea disaster due to upstream water diversion.

• Colorado River disputes among U.S. states and Mexico.
  These conflicts arise due to competing demands and transboundary water issues.