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Species, Populations, Communities Interactions in Water Ecosystems We are being hired to: • Research for writers of a science fiction book and screenplay. • The writers want to create a doomsday scenario in a scientific, research-based context Our job: Provide comprehensive input about: • Physical, chemical, and biological properties of water environments • Species interactions • Population dynamics • Human impacts water ecosystems • • • • • • Marine (Ocean) / Reefs Mangroves / swamps Estuaries / Wetlands / Lagoons River / Riparian Lake Ice / Glaciers Physical, Chemical • • • • • • • Geographic location or location type Zones Light Temperatures Presence of oxygen, nutrients, salt Geological factors – rock, soil Chemical factors – inorganic reactions Biological • • • • Species and Niche Community Properties Environmental Pressures Population Dynamics Properties of Water • • • • • • • • • Makes up 70% of Earth’s surface 97% is salt, 2% is frozen, 1% is fresh Greatest density at 4° C. Due molecular polarity, it has high adhesion High Specific heat - can absorb energy without rapid temperature increase Ice (solid) is less dense than liquid form The most common solvent – ionic compounds dissolve readily Acid, base, neutral pH depending on solutes Conducts electricity if salts are dissolved Geographic Location or type Mangroves occur along coastlines in tropical climates Geographic Location or type Wetlands occur at different latitudes Zones - ocean • Different depths have different characteristics • Ocean depths range to 5 miles • Energy sources range from solar to volcanic Zones - Lake Different depths have different characteristics. Light, oxygen levels, and temperature all determine plant, animal, decomposer communities Light While water depth determines how much light gets through, turbidity is also a huge factor. Turbidity of a water body can be impacted by natural and human activity, and turbidity impacts water ecosystems. Temperatures change seasonally, changing water density Ocean temperatures: latitude and currents Arrows show the direction of water flow. The white current is the Gulf Stream, which flows along the East Coast of NA, across the Atlantic Ocean, and warms Western Europe. Presence of oxygen, nutrients, salt Geological factors – rock, soil Sea sediment Jasper Rare Earth metal deposits Human Impact • Chemicals – – – – – Fossil fuel combustion biproducts Manufacturing effluent N2 and PO4 Fertilizers eutrophism, algal blooms Herbicides, pesticides, pH • Sediment – Land management – Forest management (or mismanagement) • Fecal matter – human and animal waste • Garbage • Temperature – Manufacturing effluent – Global warming Biosphere • Tolerance for environmental conditions • Limiting factors – temperature, nutrients, space, oxygen Community properties • • • • Primary productivity Biodiversity – species richness Abundance – # of organisms of a species Complexity – # of species at each trophic level – The more complex the food web, the more resistant it is to disturbance Communities in Transition Primary Succession – life has never been there and it starts Secondary Succession – life was destroyed and returns Climax Community – life has developed complexity, abundance, and can develop no further Species and Niche NICHE – an organism’s role in the community Generalists – can survive in a wide range of habitats Specialists – survive in only a narrow range of habitats Indicator species reflect living conditions Keystone species – Exotic species – play a significant compete with role; other species natives depend on them LAW OF COMPETITIVE EXCLUSION No two species can occupy the same niche and compete for the same resources. This will lead to either: – Extinction of one species – Behavior change • Temporal isolation • Geographic isolation • Symbiotic cooperation – Genetic change: Adaptation Adaptation - Natural Selection • Genetic traits that survive in harsh conditions are passed onto offspring • When members of a population are isolated by (ecologic or geographic) barriers, they can change enough to become a separate species Population Change • • • • • J-curve - exponential growth without limit S-curve - growth that responds to limits Doubling time – 70 / rate of growth Oscillation – cycles of growth and decline Species Type – r-adapted: high reproduction, high mortality – K-adapted: few offspring, larger, live longer Factors that impact populations • • • • • Fertility Mortality Life expectancy Emigration Abiotic factors – human impact on Earth Systems – natural disasters • Stress and crowding • Conservation / Restoration efforts