lec 14 Flashcards
Terrestrial abiotic factors which shape diversity
Sunlight, Temperature, Precipitation, Nutrients, wind, latitude, altitude, soil type
Aquatic abiotic factors which shape diversity
Light (Penetration) Water temperature Nutrients Water Currents Salinity Nutrients
Most important factor in organism distribution _____
It has a significant effect on _______
But this is complicated because
Temperature
Biological factors
Most organisms can not regulate their body temperature
Smaller animals must _________ to maintain their body temperature
spend more energy
Large animals body temperature is ________
slower to change
Reef-building corals require warm water conditions to survive. Different corals living in different regions can withstand various ________ ________
Temperature fluctuations
Coral reefs have the greatest biodiversity within
within the seas and perhaps the Earth
Many corals consist of a symbiotic association made up of an invertebrate animal and algae
This symbiosis is ____ ______
light dependent
and part of the reason we see coral declines in warming waters is the impact of turbidity on the algae
In aquatic environments, water absorbs light preventing photosynthesis at depths greater than
100m (photic zone)
The photic zone value is not _____ and fluctuates with turbidity and biological activity
static
As light penetrates water different wavelengths are
lost before others
Abiotic factors that affect diversity- salinity
Aquatic organisms must maintain osmotic balance (i.e. keep internal salt levels constant)
Freshwater fish are hypertonic and tend to
gain water and have to constantly eliminate water
Marine fish are hypotonic and tend to
lose water to the environment and must drink water to compensate
There is a strong relationship between terrestrial systems relating to temperature and precipitation
With low precip and low temps you get tundra
Low precip and high temps results in deserts
High precip and high temps result in rainforest
Strangely we have no niches containing high precip and cold temperatures
The full collection of environmental variables come together to form Biomes which are
regions of homogenous structure
Tropical forests: light and nutrients are in high demand. They have
A thick canopy blocks light to bottom strata, in response many trees are covered by epiphytes, or, can survive with low light
Species richness: extremely high
Tree species > 100/km2
Large mammals are less common though birds and ectotherms abound
One of the largest terrestrial biomes on Earth is the taiga (Boreal forest). It has
Moderate moisture and long cold winters
Species richness: is relatively low but varies season to season
Ectotherm diversity such as amphibians and reptiles are low
Grasslands occur where the moisture is too low to support forests. They have
Inter-continental climate (cold winters, hot summers)
Marked by seasonal drought and fires, and grazing by large animals
Species richness: plants (fairly high), animals (relatively low)
Soil very rich in nutrients
Considered the most endangered biome worldwide (1% of North American prairie left)
Tundra or permafrost (Permanent frozen ground) are bitterly cold, have high winds, low moisture, no trees, short growing season. It
Covers 20% of land surface on earth
Low species richness (animals and plants)
Fauna much richer in summer (migratory birds)
Deserts are defined by lack of moisture. They have
Plants and animals have adapted for water storage and conservation
They Can be either very hot, or very cold (e.g. Antarctica)
Moderate to very low species richness
Aquatic biomes cover 75% of the earth’s surface, they contain
the majority of living space (>90%)
Freshwater in northern climates go through annual cycles
In early SPRING water is 4 degrees Celsius from top to bottom
Density of water is uniform from top to bottom as is the oxygen distribution
As atmospheric temperatures warm in the SUMMER, _______ _______ sets in from heating of the surface waters
thermal stratification
Temperature differences in water column create different water densities
Lighter warm surface water floats on denser deep cold waters
Deep waters remain cold all summer; do not mix with warm surface water
Oxygen is now higher at the surface and low at depth
Zone between warm and cold water is the
thermocline
As FALL sets in heat declines, surface waters cool, density gradients are lost
Water column mixes top to bottom again as in spring
Barriers are eroded and deeper waters become re-oxygenated
Water column reaches a uniform temp of 4 degrees Celsius again
Ice forms at surface as water cools to 0 degrees Celsius
In winter a unique property of water emerges which is to become very dense at ~4 degrees Celsius
An inverted temperature profile is established
Less dense ice forms at the surface as water continues to cool
Ice insulates and further cooling and ice formation stops
Water column again becomes thermally stratified
Freshwater lakes can be divided into two types:
Oligotrophic lakes and Eutrophic lakes
Oligotrophic lakes are
nutrient poor, water is clear, cool and oxygen rich; little productivity by algae, often have high diversity of fish
Eutrophic lakes are
nutrient rich, lots of algal productivity, oxygen poor at times, high algal diversity, but low diversity of fish (winter/summer kill likely)
Rivers are heavily affected by human activities; most large rivers are now _______ at multiple points along their length
dammed
Benthic (bottom dwelling) algae and aquatic insects are a highly diverse group in rivers but sensitive to
changes in turbidity, temp and nutrient loading
Wetlands includes marshes, bogs, swamps and seasonal ponds
These are habitats of high
biodiversity and productivity
Many wetlands have been lost (>70% on Plains), resulting in
increased flooding; wetlands act as a natural reservoir capturing heavy rains and snow melt
An estuary is
where freshwater stream or river merges with the ocean
Highly productive biome; with many euryhaline species, sensitive chemical balances at risk
Estuaries depend on
a dynamic but predictable salt cycle which is easily disrupted by human activities
the pelagic zone is at risk from
overfishing and pollution
Mangroves are
very frost sensitive, and only found between latitudes 25oS and 25oN where wave action is minor
Mangroves
cover 60-75% of tropical coastlines and support a rich fauna of birds in tree tops, and snails, barnacles, oysters, and crabs below
Mangroves have sheltered waters around roots which
provide nursery habitat for organisms
reef building corals require _______
But different corals
warm temperature conditions to survive
