Define the term Ecology
Ecology is the scientific study of the interactions that determine the distribution and abundance of organisms.
Organisms interact with their environment and are the product of adaptation trough evolution (natural selection).
Define the term Fitness
Fitness is the measure of a genotypes long-term success.
Fitness is always relative to the other species in the system (no maximum -> optimization) and the species which can sustain the largest growth is the fittest.
The two main components are reproductive potential and survival.
Abiotic Factors of aquatic ecology: Temperature
The range of temperature changes is smaller in water than on land, therefore temperature is less lethal to aquatic organisms. The temperature is very important for the speed of physiological and biochemical processes.
Abiotic Factors of aquatic ecology: Oxygen
The solubility of O2 is limited and depends on temperature, salinity and pressure.
To handle limited and fluctuating O2 concentration, organisms developed different coping mechanisms (O2 take-in over whole body, using atmospheric O2, hemoglobin with high O2,…)
Abiotic Factors of aquatic ecology: pH
Changes can directly lead to damages and disfunctions due to the role of pH in the ion transfer through cell membranes.
Indirectly it can change the solubility of metals, the dissociating of ammonium ions and the equilibrium of calcium-carbonic acid.
Abiotic Factors of aquatic ecology: Other ions
(Salinity) Species in freshwater must maintain their ions and are surrounded by more diluted water and must constantly remove water to retain their salts.
Because this does not happen in saltwater there are very few species which can live in the in between of both (river deltas).
Abiotic Factors of aquatic ecology: Water flow in streams
Water flow in streams are responsible for the continuous change in resources.
They can be disastrous if they are fluctuating.
Morphological and behavioural adaptations to cope with these challenges.
Abiotic Factors of aquatic ecology: Density
Most organisms are denser than water and must swim (high energy cost) or reduce their sinking speeds through adaptation to stay afloat.
Resources: Light
6CO2+6H2O —> C6H12O6 + 6O2
Light is not a boundary condition for photosynthesis
Resources: Dissolved inorganic carbon (DIC)
Mainly dissolved CO2, carbonic acid, carbonate ion and bicarbonate ion.
Resources: Mineral nutrients
Macroelements (N, P, S, K, Mg, Ca, Na, Cl)
Trace elements (Fe, Mn, Cu, Zn, B, Si, Mo, V, Co, etc.)
Resources: Inorganic energy sources
Chemolithoautotrophic bacteria are extremely important for nutrient cycling in freshwater.
Resources: Anaerobic respiration
Heterotrophic bacteria use DOC as source of energy.
Resources: Dissolved organic substances (DOC)
Most organic matter in lakes is dissolved
Mostly important as energy and carbon source
Mixture of several substances
Resources: Particulate organic substances (POC)
Occur as either living or dead matter (detritus)
In streams POC can be exclusively detritus.
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