Bio Exam

What is stress?

Anything that changes the "milieux Interieur" (Claude Bernard). A disruptor of homeostasis (Walter Cannon)

Hans Selye (1902-1982)

When working in Montreal he discovered that the stress response of the body is related to the magnitude of the stressor. He pioneered research on stress, in which he defined the General Adaption Syndrome

3 "stress" phases

Alarm, resistance and exhaustion

"Alarm" phase

The immediate reaction to a stressor. The magnitude of response is related to the magnitude of stressor.

"Resistance" phase (adaption)

If the stress continues the body adapts. Cortisol, Epinephrine, growth hormone and thyroid hormones. General metabolic changes to cause peripheral tissues to use fatty acids and amino acids for energy and spare sugar, fuel the brain! Conservation of salts and water to maintain blood pressure.

"Exhaustion" phase (chronic, long-term stress)

Insomnia, fatigue, loss of appetite, lethargy, etc. Metabolic changes include exhaustion of lipid reserves, muscle wasting, structural and function damage to vital organs, loss of potassium contributing to cellular malfunction, hypertension, amenorrhoea in women, and reduced sperm quality in men.

Population ecology

Dispersal ranges, migration, population growth, reproductive strategies (r,K)

Species interactions (K. Hillier)

competition, herbivory, plant defences, top-down and bottom-up processes, etc.

Community ecology (K. Hillier)

Species richness, diversity, succession and stability, food webs and energy flow, biomass production

Ecosystems (G. Gibson)

The biotic community of organisms living in an area, as well as the abiotic environment affecting that area

Biomes (G. Gibson)

A biome is a large community of vegetation and wildlife adapted to a specific climate.

Biosphere (G. Gibson)

The regions on the surface of the earth and atmosphere where living organisms exist

Challenges to Biodiversity (G. Gibson)

Biodiversity- is the variety of life in the world or in a particular habitat or ecosystem

Ecosystems

The biotic community of organisms living in an area, as well as the abiotic environment affecting that area

How energy flows (see Kirk’s lectures) and nutrients cycle through communities

Water, Carbon, Nitrogen, Phosphorus

Energy flow

ultimately lost from an ecosystem as heat

Nutrients

continuous cycle from organisms to an abiotic component of an ecosystem

Organisms require 30-50 different nutrients

Macronutrients (carbon, hydrogen, phosphorous, potassium etc.)

Nutrients originate from the soil, water and air, but organisms acquire them in different ways

Autotrophs (e.g., plants) take them up directly from abiotic sources
Heterotrophs (e.g., animals) acquire them by consuming other organisms

Carbon cycles

Carbon makes up macromolecules that are important to life
Much of the energy that organisms use to fuel their activity comes from carbon-containing compounds

Carbon cycle on land

carbon is cycled between organisms and the atmosphere
Photosynthesis: plants take up carbon
Respiration & metabolism: carbon returned to the atmosphere

Carbon cycle in the ocean

carbon dioxide diffuses into the water at the ocean surface; dissolved CO2 taken up by primary producers

Fossil fuels

carbon that was removed from natural cycling & stored, following mass die-offs of organisms, buried in anaerobic sediments

Water

essential element and transports nutrients between compartments.
Cohesive
Transport
High surface tension
Supports small organisms
Upward movement in soil and plants
solvent
low viscosity
high heat capacity
carries waste heat, high heat of vaporation
expands during freezing, ice floats, freeze from the top down

Water availability affects the distribution of organisms

Water buffalo - Grass availability is influenced by rainfall in the previous months. Buffalo density depends on grass availability
Spadefoot toad - In dry season they burrow underground in the drip line of plants, at the start of the rainy season they come out and mate

The water cycle (hydrological cycle)

Primarily physical (not chemical) cycle
Evaporation
Precipitation
Driven by solar energy
Water evaporates from the ocean
Evapotranspiration from soil and land plants
Overland 90%% of the water that enters the atmosphere has passed through plants and evapotranspiration from the leaves
Atmospheric water condenses into clouds
Precipitation

Aquifer

a porous underground deposit that holds water bounded below (and sometimes above) by an impervious layer (e.g., bedrock)
Moving and part of the water cycle
Water can remain in an aquifer for days to 10,000 years
The sole source of fresh water for 30% of Canadians

Water table

upper level of saturation of the aquifer

Contamination of aquifer

chemical contamination, agricultural runoff (heavy rain), drilling, landfills, accidental spills

Residence time of the worlds water supply

Oceans and seas - approximately 4000 years
Lakes and reservoirs - approximately 10 years
Swamps - approximately 1 to 10 years
River channels - approximately 2 weeks
Soil moisture - 2 weeks to 1 year
Ground water - 2 weeks to 10,000 years
Ice caps and glaciers - 10 to 1000 years
Atmospheric water - approximately 10 days

Biomes

Characterized by physical characteristics such as temperature and precipitation
Also: soil type, wind, and others
Availability of water

Grasslands

characterized by grasses (e.g., prairie, savannahs and steppes), trees sparse, semi-arid, may be in warm or cold climates

Forest ecosystems

characterized by trees, classified by climate (tropical, temperate or boreal)

Desert ecosystems

low precipitation (

Tundra ecosystems

arctic & alpine, snow-covered, windswept, treeless, dry (less rain than most deserts),  the soil may be frozen year-round (permafrost). 

Freshwater ecosystems

stationary water (ponds) or flowing (streams & rivers), also bogs, lakes and swamps.

Marine ecosystems

salt water, the most abundant types of ecosystems in the world (ocean floor to surface, intertidal, estuaries, salt marsh, swamps, mangroves, coral reefs).

Effects of the environment on the distribution of organisms

\-Water availability

\-Carbon cycles

\-Tides & currents (Dr. Stokesbury)

\-Temperature

\-Salinity

\-pH

\-Wind

\-Light

Physical effects of low temperatures

frost and ice damage causes cells to rupture

Physiological (functional) effects of low temp

enzymes are temperature sensitive (enzymes- proteins that speed up chemical reactions inside a cell)

Effects of temperature

Limit the distribution of tropical and subtropical species

White clover- produces cyanide as a defense against herbivores

•When the cells freeze, the cyanide is released from the cell, killing cells nearby

•More northerly populations have fewer individuals that produce cyanide

Wood frogs - overwinter in leaf litter

•Freeze-tolerant- move water from inside their cells to the inter-cellular spaces, and freeze solid

Keystone species

a species that has a major effect on shaping an ecosystem (disproportionate to its abundance or biomass)

High temperatures

Keystone species in forest ecosystems

Jackpine- require fire to melt the resin that holds the cones together, releasing seeds

•Giant sequoia- require fire for seed germination

•Prescribed burns in Australia

•Decrease ‘tinder’ and reduce risk of wildfires, lets more light into the forest floor- small plants and germination

•Damages large trees, small mammals, reptiles, insects, etc.

Effects of temperature on coral reefs

•Deposition of calcium carbonate (skeleton) is temperature dependent

•Accelerated at warm temperatures, suppressed in cold water

•Warm-water coral reefs: distribution limited to regions with 20ºC average daily temp in the coldest months of the year

Coral bleaching

•If water temperatures are too high, the symbiotic algae that live within the corals die and are expelled; corals lose their colour

•Mutualism

•Corals provide algae with a home and nutrients (ammonium)

•Algae provide the corals with oxygen, glucose and other nutrients

•Relationship started \~210 million years ago

•Coral species that host algae deposit calcium 10x faster than species of corals that don’t

Great Barrier Reef- mass bleaching event (2006)

elevated water temperatures of as little as 2ºC for a few weeks was enough to kill 50% of the corals in a region of the Great Barrier Reef (change in weather patterns brought in warmer waters)

•Three months later, some of the corals had taken up a more heat-tolerant alga

•Short-lived adaptation- months after that, the corals had re-acquired the original (pre-bleach) alga species

Are there cold-water corals?

•Yes- and in Nova Scotia

•E.g., Georges Bank, moratorium on gas and oil exploration and drilling

•25-30 species

•Deep water (200-1300m), like the cold (3-8ºC water)

•(Some species of corals in shallow waters off Nova Scotia)

•Slow growing (\~1 cm/ year), live for decades

Foundation species

dominates in terms of abundance; here, provides habitat for other species

Temperature- environmental sex determination in reptiles

Genetic sex determination

* Snakes, most lizards

Environmental sex determination

* Most turtles, all crocodilians

Reptiles

•Some species- environmental sex determination

•Incubation temperature activates sex-determining genes (individuals have the genes to express both sexes)

•After, sex is fixed (irreversible)

•Pattern by which this occurs is highly variable

•Others- genetic sex determination

Temperature of sex determination for reptiles

Low temp (

Salinity

effects water density, thermal capacity, biochemistry, availability of nutrients and metals; these in turn effects who can live there

Osmotic balance

ensures optimal levels of salts and water across cells and tissues in the body

The movement of water across the cell membrane to balance solute (e.g., salt) concentrations

•Maintains body functions

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Effects of salinity on an ecosystem

•Oceans have more dissolved minerals than rivers; as the sun’s energy evaporates water from an aquatic ecosystem, mineral concentration increases

Freshwater fish

\-Hyperosmotic: more salts in their tissues than in the surrounding environment

\-Gain water by osmosis (e.g., water crosses into the gills)

\-Lots and lots and lots of urine

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Saltwater fish

\-Hypo-osmotic: less salt in their tissues than in the surrounding environment

\-Lose water by osmosis (e.g., water crosses out of the gills)

\-Little urine

Salinity and plants

pH

concentration of hydrogen (H+) ions

Few terrestrial plants are adapted for high salinity ecosystems

Halophytes- species that tolerate higher salt concentrations in their cells than regular plants

Saltbush - Used in environmental remediation to remove salt from contaminated sites

Spartina- Salt marsh hay, have salt glands and excrete salt onto the surface of their leaves

Factors that effect pH of soil and water

Carbon dioxide (e.g., respiration, bacteria, etc.)

•Organic matter

•Geology

•Air pollution (e.g., sulfur dioxide)

•Water from abandoned coal mines

•Acid rain

•Burning

•Long-term clear cutting (Fig. 54.14, right)

•Normal rainwater pH 5.6

•Most plants thrive in soil of pH 6.5- better availability of nutrients

•Alkaline soils- chalk and limestone- higher pH & richer (more diverse) flora 

Ecosystem services

the benefits people obtain from an ecosystem

pH, plants and ecosystem services

•Balsam fir and white ash- both acid sensitive trees

•Both important members of the Acadian forest

pH and aquatic life

•Optimal pH for most freshwater fish is between 6.0 and 9.0

•Low pH

•Alters water chemistry, increases the availability of toxic metals (e.g., mercury)

•Changes gill structure, decreases survivorship of embryos, changes hormone production in males, decreases salt tolerance in smolts (the life stage that goes to the ocean), decreases ability to detect predators

Ecosystems

The biotic community of organisms living in an area, as well as the abiotic environment affecting that area

What about contaminants?

What are microplastics?

\-Small pieces of plastics that are < 5 mm long

\-Nanoplastics < 1 µm (red blood cell \~ 7.5 µm)

\-Chemically diverse

\-Highly persistent in the environment- water, soil and air

How humans ingest microplastics

Inhalation

•Drinking

•Ingestion

•Skin contact

Bioamplification/ biomagnification

increasing concentration as we move up trophic levels

Bioaccumulation

increasing concentration within an individual, with repeated exposure over time

What about contaminants?

Both petroleum-based and biodegradable microplastics disrupted tissue structure of the digestive gland

\n Take home message: both BPA & BPS disrupt regeneration in a polychaete

Ecosystems

a system formed by a community of organisms and its physical environment

Biomes

major types of habitat characterized by distinctive plant and animal life

•Subdivided into terrestrial and aquatic

•Characterized by physical characteristics such as temperature and precipitation

•Also: soil type, wind, and others

shaped by global climate

Biosphere

The regions on the surface of the earth and atmosphere where living organisms exist

Aquatic Biomes

Classified by:

\-Water salinity

\-Current strength

\-Water depth

\-Oxygen content

\-Light availability

Weather

 short term state or atmospheric conditions in a particular place and time

\-Behavioural responses of organisms

Climate

Average atmospheric conditions in a particular place over a longer time (years to millennia)

Filter that determines distribution and abundance of organisms

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Abiotic factors

major players in shaping the distribution of life on earth

What creates climate patterns?

\-Patterns of solar radiation

\-Rotation of the earth

Patterns of solar radiation

•Solar energy hits the earth

•30% reflected

•Most is absorbed by the Earth’s atmosphere (20%) or surface (50%)

•The atmosphere traps heat energy and moderates the earth’s temperature

•Greenhouse gases

•Allow sunlight in but trap heat energy

•Greenhouse gases include CO2, H2O, methane, O3, nitrous oxides (NO and NO2), and pollutants such as chlorofluorocarbons (CFCs).

Differences in solar input explain why average temperatures vary with latitude

•High latitudes- solar input more spread out, and more energy is absorbed in the atmosphere

•Near equator- solar input more focused and direct

•Temperature in the northern hemisphere more variable than southern hemisphere

Tropical rainforest

•Rainfall exceeds 230 cm/ year

•Temperature averages 25-29C

•Shallow soil, nutrient poor

•Extensive biome, equatorial

•Rich animal and plant life

Hot desert

Rainfall < 30 cm/ year

Temperature variable (below freezing to 50C)

Plant life highly specialized

Reptiles (ectotherms), seed eating insects and mammals

Temperate forest, e.g., Wabanaki/ Acadian Forest

Rainfall 75-200 cm/ year

Temperature variable (-15 to 30C)

Plant life: sugar maples, red spruce eastern hemlock

Tundra

Rainfall < 25 cm/ year

Permafrost

Temperature: midwinter averages -32, summer 3-12C

Plant life: lichens, mosses, grasses, some shrubs but no trees (lack of water)

Animals: birds, hares, caribou

Earth rotates

producing prevailing winds

•Earth’s rotational speed is fastest at the equator, slowest at the poles

•Coriolis effect- deflection of air or water as a result of differences in the Earth’s rotational speed at different latitudes

Wind zones:

\-Polar easterlies (cool dry air sinks back to surface of the earth)

\-Westerlies (temperate)

\-Trade winds (easterly)

\-Equatorial low

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Prevailing winds drive ocean currents

•Ocean currents driven by prevailing winds (frictional drag)

•E.g., trade winds cause currents at the equator to move west until they hit a continent

•Deflected north and south

The tilt of the earth’s axis and rotation result in seasons

Tilt + Earth’s orbit changes the amount of sunlight a particular region gets over the course of the year

\- Variation in temperature and daylength

*When the Southern Hemisphere is tilted towards the sun, it is summer there and winter in the Northern Hemisphere*

*When the Northern Hemisphere is tilted towards the sun, it is summer there and winter in the Southern Hemisphere*

Biosphere

The regions on the surface of the earth and atmosphere where living things exist

Maximum height- Mt. Everest, ca. 9 km

Maximum depth-Mariana Trench, ca. 11 km

(average 3 km)

The maximum thickness of the biosphere = 20 km

0\.16% of the thickness of the planet

Arctic

a __highly seasonal environment,__ and can be variable depending on proximity to (moderating) coasts

Snow

•Max in January, minimum in August (contrast with sea ice)

•For much of the Arctic, can fall in any month (next)

•Polar desert – snowy, but not a lot of snow (it just doesn’t melt!) … (Cold air holds less moisture than warm air)

•Snow  and its melt regulates water supplies; insulates tundra surface; provides cooler local microclimate

Sea Ice

Slightly different timing that snow cover

(max in February, min in September

Permafrost

•*Periglacial* features (associated with glaciers or with repeated freezing and thawing of ground)

•Pingos

•Patterned or sorted ground

Arctic Cordillera

E. Ellesmere

E. Devon

E. Baffin

N. Labrador

•Mountainous (2000 m)

•Steep coastal cliffs

•Deep fjords

•Glaciers & ice caps

•Increasing vegetation moving south

•Relatively unproductive

Polar desert

•“Devoid of life” appearance

•Like the moon

•Exposed sedimentary rock (glacial till, etc.)

•Very little soil development

•Few nutrients

Arctic Plain

Some broad, flat parts of this region support Arctic meadows

Not lush lush, but HUGE so collectively important

Life in and on sea ice

•Sympagic environment

•Where water is mostly solid, like sea ice

•Different that freshwater ice; many brine channels

•Many algal and zooplankton organisms live here

•Creates an entire food web or biotic community

•Often more developed under multiyear ice

Sea-ice as a habitat

•Subnivean

•Certain sea ice areas not suitable as snow does not build up

Of course, there’s iconic Arctic wildlife …

•Generally well-adapted to relying on limited water (often getting water from metabolizing fat)

•Very well-insulated; shed heavy coats for summer

•Migrate (e.g. 268 bird species in summer to \~8 in winter)

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Polar bears

Fat makes them very buoyant

Have been observed swimming 320 km from land, an average of 155 km

Acoustic Technology

Coded acoustic transmitters – Send information such as a unique ID + temperature or pressure (depth) – Transmit every 30-60 s – Detected by receivers if tagged fish is within range

Atlantic Sturgeon

Primitive, Anadromous fish • Mature at age 20 – 28 • Grow to be 3 - 4 m • Summer aggregation (feeding) • Weir and trawl commercial fisheries • Annual feeding aggregation in Minas Basin (N = app. 10,000, mostly sub-adults) • Genetic analysis (Wirgin et al. 2012) indicates that : – \~60% of Saint John River stock – 32-34% Kennebec River stock – 1-2% Hudson River stock

Biodiversity

the variety of life forms that exist now and existed in the past

Biodiversity hot spots

regions that are biologically diverse and are under threat of destruction