Aquatic Ecology Environmental Factors for Aquatic Life Light

Aquatic Ecology

Environmental Factors for Aquatic Life • • Light penetration p. H (acidity / alkalinity) Salinity (salt content) Dissolved Oxygen (DO) Mineral nutrients Water depth Water movement (currents, flow rates)

Life in aquatic ecosystems • Plankton: free-floating, carried by currents / waves. Ex: Phytoplankton (photosynthetic) and Zooplankton (animal-like). • Nekton: free-swimming organisms. Ex: fish, turtles. • Benthos: “bottom dwellers” Live in the benthic zone (sponges, crabs, clams), some may be sessile (meaning they do not move)

Freshwater ecosystems • Are classified as: - standing (lakes and ponds) - flowing (rivers and streams/creeks) - wetlands (swamps, marshes, and bogs)

Aquatic zones in lakes and ponds • Littoral zone – the shallow area of soil and water near the shoreline. Many photosynthetic organisms find habitat in this zone. Ex: algae & rooting plants like cattails. • Limnetic zone – deeper, open water where no rooting plants can find habitat. The zone extends down as far as light can penetrate. Free-floating organisms find habitat here. Ex: algae (phytoplankton)

Aquatic zones in lakes and ponds • Profundal zone – deeper water below the limnetic zone. No photosynthetic organisms grow here. Bacteria feed on detritus from the limnetic zone. • Benthic zone – the muddy bottom of a lake or pond below the profundal zone.

Aquatic zones Benthic Zone Profundal Zone

Freshwater Wetlands -Characteristics • Areas submerged or saturated by water for all or part of a year. • Shallow enough to support emergent vegetation. • Vegetation specialized to live in submerged or saturated soils. • Categories of freshwater wetlands include: swamps and marshes, and bogs.

Freshwater Wetlands -Types • Swamps: wetlands that contain emergent trees such as bald cypress. Ex: Okefenokee swamp (GA) and Great Dismal swamp (VA/NC) • Marshes: contain mostly non-woody vegetation such as cattails and sedges. Most of the Florida Everglades is this type. • Bogs: higher in acidity than other wetlands. Sphagnum moss and spruce trees are often found in bogs.

Freshwater Wetlands -Functions • They help reduce the severity of droughts as they receive large amounts of rainwater then slowly release it to groundwater or surface water systems. • They help to filter pollutants from water. • They serve as migratory stops and breeding areas for many bird species. (many of these species are endangered)

Freshwater Wetlands -Issues • Many wetland areas have been drained for agricultural use or development. • Some have been drained for the purpose of reducing mosquito breeding grounds. • An effort to offset unavoidable wetland impacts is called “wetland mitigation. ” The result of this effort is to incur no net loss of wetland function by creating new wetlands, restoring previous wetlands, or protecting adjacent wetlands.

Florida Everglades 1904: Napoleon Bonaparte Broward was elected Governor on the promise to create an "Empire of the Everglades, " by wringing the last drop of water out of that "pestilenceridden swamp. " 1906: Dredging began on the North New River Canal, the first in south Florida's system of drainage canals

Estuaries • Areas where freshwater and salt water meet. (the resulting mix is called “brackish water”) • They are partially surrounded by land, and have open access to the ocean, and they have a large supply of freshwater from rivers. • They are extremely productive ecosystems, and they contain a high species diversity.

Salt Marshes • Salt marshes: are found along the coasts of areas with temperate climates. • Similar to freshwater marshes, they contain non-woody emergent vegetation. • Many are found in estuaries. • They provide habitat for spawning fish and shellfish.

Mangrove swamps (aka: Mangroves or Mangrove forests) • Mangrove swamps: occur along tropical and subtropical coasts. • They contain trees that tolerate high salinity and moisture. • They often occur in estuaries & provide coastal protection from erosion and storm damage. • They have soils rich in nutrients, and they are habitat to many species of fish and shellfish.

• 35% of Mangroves are already gone. • The threats to mangroves may be natural: climate change, invasive species, insect damage. • Or threats may be anthropogenic: urban development, overharvesting (wood), pollution, water diversion projects.

Trophic states of aquatic ecosystems • Trophic means “nutrition” or “growth” • Oligotrophic: body of water has low nutrient concentrations, and low plant growth • Eutrophic: body of water has high nutrient concentrations and high plant growth. • Mesotrophic: falls between oligotrophic state and eutrophic state.

Trophic states of aquatic ecosystems • Factors that regulate trophic states: – Rate of nutrient supply: from human land uses, soil type, watershed geology, vegetation – Climate: amount of sunlight, temperature, precipitation. – Morphometry (shape of the water body’s basin): depth, volume, surface area, watershed to surface ratio.

Trophic states of aquatic ecosystems • Eutrophication: the progression of a body of water to a eutrophic state. (typically lakes/ponds) • This occurs when nutrient concentrations increase in a body of water. • It may be natural or cultural (also called artificial) – Natural Eutrophication: occurs from natural nutrient sources (runoff from soils high in nutrients) – Cultural Eutrophication: occurs when runoff from human activities contain high amounts of plant nutrients (such as nitrates and phosphates). Ex: livestock or crop farms, discharge from industries.

Marine ecosystems • Oceans: help to control Earth’s climate, dilute and disperse human wastes, biogeochemical cycling (water, carbon , nitrogen, phosphorus) • The basis of the ocean food chain is phytoplankton. • The ocean, like bodies of freshwater, is classified into zones: Coastal, intertidal, open ocean, benthic

Marine ecosystems - Ocean zones • Intertidal: nutrient-rich, ample light penetration, high DO. Organisms are subject to high and low tides, and wave activity. • Coastal: also called “neritic zone” covers the continental shelf, where 90% of all ocean life exists. It is highly productive. • Open ocean (“Oceanic” or “Pelagic zone”). The largest part of the marine environment, but the least productive. -Classified as: euphotic / photic (light penetrates) aphotic (light does not penetrate)

Marine ecosystems - Ocean zones continued • Benthic: “ocean bottom” - In shallow areas it is highly productive. Coral reefs and kelp forests are found here, which provide habitat for a variety of marine organisms. - In deeper areas bottom feeders consume organic matter from dead marine life.

Ocean zones