Marine and Freshwater Ecology Study Notes

Intertidal Adaptations: Organisms demonstrate adaptations such as the ability to attach strongly to substrates (e.g., shells or suction) to withstand wave action and shells that close to prevent desiccation during low tide.
Organisms: Examples include barnacles and sea stars.
Net Primary Productivity (NPP) Equation: $NPP = GPP - R$
Energy Sources: While terrestrial ecosystems rely on sunlight, marine food chains similarly rely on sunlight to fuel phytoplankton, though deep-sea chains may rely on chemosynthesis.
Salinity: Freshwater biomes have very low salinity (usually less than $1\,ppt$ ), whereas saltwater biomes have high salinity (averaging $35\,ppt$ ). Examples include lakes (freshwater) and coral reefs (saltwater).

Productivity Levels:
- High Productivity: Estuaries and Coral Reefs.
- Low Productivity: Open Ocean (Pelagic zone) and Abyssal zone.
Thermocline: An abrupt temperature gradient that can act as a barrier, preventing the mixing of nutrient-rich deep water with oxygen-rich surface water, thus limiting productivity.
Euphotic Zone: Extends from the surface to approximately $200\,m$ deep. It is unique as the only layer with sufficient sunlight for photosynthesis.
Light Penetration: Blue light penetrates the deepest into the ocean, followed by green light.
Ocean Layers (Shallowest to Deepest): Euphotic zone, Disphotic zone, Aphotic zone.

Commercial Aquaculture:
- Benefits: Increased food security and reduced pressure on wild fish populations.
- Drawbacks: Waste accumulation (nutrient pollution) and the potential spread of diseases to wild species.
Coral Bleaching: Primarily caused by increased ocean temperatures (thermal stress) which leads to the expulsion of symbiotic algae (zooxanthellae).

Pollution Sources:
- Point-source: A specific, identifiable discharge pipe (e.g., a factory drain).
- Nonpoint-source: Diffuse runoff from large areas (e.g., urban or agricultural runoff).
Oxygen Sag Curve: Occurs after a pollution spill (like sewage) when the Biological Oxygen Demand (BOD) spikes as bacteria decompose waste, leading to a sharp drop in Dissolved Oxygen (DO).
Deepwater Horizon Consequences: Economic loss in the fishing/tourism industries, destruction of coastal habitats, and massive wildlife mortality.
Oil Cleanup Methods: Booms, Skimmers, Dispersants, and In-situ burning.
Sediment Pollution: Affects environments by clogging fish gills and increasing turbidity, which blocks sunlight for photosynthesis.

Microplastics: Affect ecosystems through ingestion (causing internal damage or starvation) and the leaching of toxic chemicals into the food web.
- Primary: Intentionally manufactured small (e.g., microbeads).
- Secondary: Resulting from the breakdown of larger plastic debris.
Thermal Pollution: Contaminates waterways via industrial cooling water discharge and heated urban runoff (e.g., from hot asphalt).

Water Quality Properties: pH, Dissolved Oxygen (DO), Turbidity, Temperature, and Salinity.
Wetland Identification: Requires hydric soils, hydrophytic vegetation, and specific hydrology (permanent or seasonal saturation).
Wetland Benefits: Provides flood control, water filtration/purification, and vital habitat for biodiversity.
Bioaccumulation vs. Biomagnification:
- Bioaccumulation: The buildup of a substance, like mercury, in a single organism over its lifetime.
- Biomagnification: The increasing concentration of that substance as it moves up the trophic levels (e.g., higher concentrations in sharks than in small fish).