Aquatic Ecosystems

Aquatic Ecosystems ~71% of Earth’s surface covered by salt water <1% fresh water 3 Major Types Marine (salt water) Freshwater (rivers, lakes, ponds, swamps, most marshes) Estuaries (coastal wetlands where fresh and salt water mix – brackish water)

Who lives there? a. b. c. d. e. Phytoplankton (microscopic plants) - algae and bacteria - producers (base of food chain) - 90% of all O2 in water comes from them Zooplankton (microscopic animals & larvae) - protozoa Nekton (strong swimming consumers) - fish, turtles, whales, etc. Benthos (bottom dwellers) - barnacles, oysters, worms, lobsters, crabs Decomposers (mostly bacteria)

Aquatic Zones Surface Middle Bottom - Euphotic Zone (“good light”) - Bathyal/aphotic (twilight/no light) - Abyss/benthic zone (complete darkness)

Temperature and salinity (________________) change _____________ Estuary What are they? Temperature and salinity (________________) change _____________ **_______________water movement stirs up the nutrient rich ____________________ which makes it readily available for ________________. Coastal wetlands – mangrove swamps & salt marshes amount of salt daily! Tides Seasonal variation in fresh water flow Spring higher – why? Unpredictable changes due to weather Heavy rain = more fresh Hurricane = more salt Constant silt/mud producers

Estuary Cont. One of the most productive ecosystems on earth! Why? ~75% of commercially valuable species spend some part of their life cycle in estuaries (great breeding grounds/nurseries). Because of food richness, great place for wildlife (birds, butterflies, sport fish, shellfish, other invertebrates) Speedy Decomposition (some communities use salt marshes to break down organic waste instead of landfills)

Benefits & Problems of Estuaries Benefits: Problems: CO2 absorption & nutrient cycling Reduce storm impact Economic Coastal habitat for humans Source of some pharmaceuticals Recreation (bird watching) Being filled in for real estate developments, marinas, golf courses, rice fields, shrimp farms Water levels rising much faster than species can adapt (global warming) Major decrease in fish harvest Increase in storm damage

Freshwater Types of freshwater: a) Standing bodies (lentic) Lakes, ponds, inland wetlands b) Flowing (lotic) Rivers, streams, creeks

Inland wetlands Characteristics: Clean water  approx. $1.6 billion worth a year! Control flooding  approx. $8-31 billion worth a year! Teeming with life (high biodiversity) Are beautiful Provide recreation (boating, hiking, fishing) Enrich our culture

Lakes Different types: 1. Oligotrophic – “few nourish” - CLEAR WATER - “new” lakes have rocky bottoms - less nutrients, less O2, few plants/animals 2. Eutrophic – “well nourish” - MURKY WATER - older lakes with silt/mud bottom - more nutrients, more O2, lots of plants/animals

Rivers/ Streams Characteristics: Moving water (Lotic = flow) Get rain water from run-off (water that is not absorbed by the ground) Carry and deposit sediment downstream O2 varies in different zones of a river Higher temp = less O2 Carry pollutants downstream also Poison estuaries

Flood control levees and dikes also have a negative impact Human use of Rivers 60% of worlds 237 large rivers are affected by dams, canals, and other diversions (irrigation) Alters/destroys habitats along rivers Reduces water flow to deltas/estuaries Flood control levees and dikes also have a negative impact Disconnect river from flood plains Eliminate breeding grounds

Marine (oceans & seas) Longer, more complex food chains and webs Zones affected by four factors - temperature - access to sunlight - nutrient availability - dissolved oxygen* *affected by Temperature Number of producers (which add O2) Consumers & aerobic decomposers (which use O2) Deep ocean circulation Deeper water = less O2 ~250,000 known marine plant and animal species YET less than 5% of oceans have been explored!! What else could be out there??

Marine (oceans & seas) What do plants & algae (phytoplankton) need to grow? Water, Light, Minerals Where is 90% of ocean life found? Why? In the Neritic Zone – plenty of water, light & minerals (all other zones lack one or more) Why isn’t it hard to “kill” oceans? Most people spend their time in the Neritic zone (fishing, drilling for oil, boating, etc)