Introduction to Ecology environments rapidly changing
--maintaining health/welfare depends on efforts to cope with environ. changes
Ecology--seeks to understand distribution and abundance of organisms
4 main levels: organisms, populations, communities, ecosystems organisms--explore morphological, physiological, and behavioral adaptations that allow individuals to live in a particular area. ex: salmon migrate from saltwater to freshwater env's population--focus on how numbers of indiv's in a population change over time (mathematical models) ex: each female salmon produces thousands of eggs. Only a few will survive to adulthood. On avg, only 2 return to stream of birth to breed. population decline because of dams and pollution. community--ask questions about the nature of the interactions between species and consequences of those interactions. ex: interactions of salmon and other species in marine communities. salmon are prey as well as predators ecosystem--study how nutrients and energy move among organisms and through surrounding atmosphere and soil or water. (impact of pollution/increased temp on species) abiotic--air, wind, soil--physical components ex: impact of pollution/- temperature on species. salmon link marine and freshwater ecosystems. salmon die and then decompose, releasing nutrients that are used by bacteria, archaea, plants, protists, young salmon, and other organisms.
Conservation biology: the effort to study, preserve, and restore threatened populations, communities, and ecosystems. particular species, partic. area, partic. population size
Types of Aquatic Ecosystems biotic--members of the same or different species interacting organisms have restricted set of physical conditions in which they can survive and thrive.
Freshwater/Saltwater--3 physical factors affect distribution and abundance of organisms: nutrient availability, water depth, and water movement.
Nutrient Availability
Many aquatic ecosystems, nutrients such as nitrogen and phosphorus are in short supply if water is moving, nutrients tend to be washed away. if still, tend to fall bottom and collect in the form of debris.
Why important?
Nutrient levels limit growth rates in photosynthetic organisms that provide food for other species.
Ocean Upwelling
Oceans, nutrients in sunlit surface waters constantly lost in form of dead organisms that rain down into the depths. In certain coastal regions of world's oceans, nutrients are brought up to the surface by currents that cause upwellings.
1. winds blow prevailing winds blow north, moving water at surface
2. surface water moves as the earth rotates, moving surface water is forced offshore
3. upwellingas surface water leaves, it is replaced by nutrient rich water welling up from the bottom
Basically, this recycles nutrients that had earlier fallen to ocean floor
Ex: when currents are favorable and upwelling is steady anchoveta fishery very happy
Lake Turnover
1. Winter stratification dense 4 degrees C water at the bottom becomes nutrient rich while colder water near surface becomes oxygenated
2. Spring Turnover surface water warms to 4 degrees C and sinks, carrying O2 down and driving nutrients up
3. Summer Stratificationdense 4 degrees C water at bottom becomes nutrient rich while warmer water near surface becomes oxygenated
4. Fall turnover surface water cools to 4 degrees C and sinks, carrying O2 down and driving nutrients up
Water Flow
Organisms that live in fast-flowing streams have to cope with physical force of water which threatens to move them downstream (esp. intertidal regions)
Nutrient and light availability influence productivity in aquatic ecosystems, water movement has effect on productivity
Water Depth
Water absorbs and scatters light, so the amount and types of wavelengths available to organisms change dramatically as depth increases
Surface= all wavelengths available. Ocean water removes light in violet and red regions of visible spectrum.