Basics ofequatic ecology Flashcards
Ecology
Is the scientific study f the interactions that determine the distribution and abundance of organisms. Organisms interact with their environment and are the product of asaption through evolution (natural selection)
Fitness
Is the measure of a genotypes long term success. Fitness is alway relatice to the other species in the system (no maximum –> optimizations) and the species which can sustaain the largest growth is the fittest. The teo main components are reproduktive potential and suvival.
Abiotic Factors
Temperature
Oxygen
pH
Other Ions
Water flow in streams
Density
Temperature
smaller range than on lang
less lethal to aquatic organisms
important for speed of physiological and biochemical processes
Oxygen
solubility is limited: depens on Temp, salinity, and pressure
To handle limitations and fluctuartion: organisms developed different coping mechnaisms
pH
damages and disfunctions due to the role of pH in the ion transfer through cell membranes
coluility of metals, …
Other Ionsa
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 between them both (riverdeltas)
Water flow in streams
responsible for changes in resources
disastrous if the are fluctuation
morphological and behavioral adaptions to cope with these challenges
Density
organisms are denser than water and must swim (high energy cost) or reduce their sinking speed through adaption to move/stay flow
Ressources
Light
Dissolved Inorganic Carbon (DIC)
Mineral nutrients
Inorganic energy sources
Anaerobis respiration
Dissolves organic substances (DOC)
Particulate organic substances (POC)
Light
formular
Light is not a boundary condition for photosynthesis
DIC
Mainly dissolved CO2, carbonic acid, carbonate ion and bicarbonate ion
Mineral nurtients
Macroelements (N, P, S, K, Mg, Ca, Na, Cl) and Trece elements (Fe, Mn, Cu, Zn, B, Si, Mo, C, CO, etc)
Inorganic energy sources
Chemolithoautotrophic bacteria are extremely important for nutreient sysling in freshwater
Anaerobic respiration
Heterotrophic bacteria use DOC as source of energy
DOC
Most organic matter in lakes is dissilved
Mostly important as energy and carbon source
Is a mixture of several substances
POC
Occus as either living or dead matter (detritus)
In streams: exclusively detrius
Populations
The definition of population depends on the abjective and the scale of the observer
Def of densiy
Abundance is the density of organisms in a defined area of water, it fluctuates over time and there are major variations between species. Abundance changes through reproduction, moratily, import and export.
Demography
Type III
juveniles have a high rate of mortality until a critical age is reaches, where the mortality falls off
The mortaliy in the remaining age groups is random
Distribution
Random (Species that do not conrol their environment)
Even (Soecies which compete among individuals, common on strems)
Clupmed (Swarms offer protection of predators, lakes or micorhabitats in streams)
Dispersal
Lakes as islands vs Rivers as continuous systems
Active dispersal vs. passive dispersal
Interactions between populations
Most species have a more limited distrbution than it would be predicted by their physiological tolerances (reason: interactions between populations)
Competition
for resources
space
position
Allelopathy or antibiosis
Direct effect of competitors through releases of chemicals that inhibit other species
Predator prey relationship
energy transfer from one organism to another
represent a mortality factor for the prey
lead to evolution of defense mechanism which lead to evolution of more efficient predators (cycle)
Examples
Grazing on phytoplankton by zooplankton (algae ward off via toxins, bad taste, digestion resistance, …)
grazing on periphyton by the microfauna, ertebrates (like fish which catch individual prey by sight)
invertebrates (detect prey by mechano- or chemoreception like water fleas)
Prey defends itself through various mechanisms like reducing their detectabiliy (colo adaption), hiding during the day, chemical defendese, fleeing
Parasitsm
predator is considerably smaller and closely associated with the prey and they do not always harm the host
Endoparasites: within the host
Ectoparasites; Ouside
Symbiosis
Positive Interaction for both parties
