Physical environment comprises temperature, wind, moisture, salinity, pH, fire.

Physical environment comprises temperature, wind, moisture, salinity, pH, fire. Physical environment is strong influence on biological distributions and processes

Earth’s shape, axis of rotation, and revolution around the sun each year, as well as physical properties of earth, air, and water determine general patterns of climate and the physical environment organisms inhabit.

The shape of the earth influences the amount of insolation different areas of the earth receive • Shape of earth also influences the direction of winds and currents • Earth’s axis of rotation and revolution around sun affect seasonality of weather patterns. • Physical properties of air, land, and water influence movement of air masses and rainfall in particular regions

The shape of the earth influences the amount of insolation different areas of the earth receive • Shape of earth also influences the direction of winds and currents • Earth’s axis of rotation and revolution around sun affect seasonality of weather patterns • Physical properties of air, land, and water influence movement of air masses and rainfall in particular regions

Coriolis effect • The deflection of wind or water due to the earth’s rotation

Problem • If a mass of air is moving from 30 degrees south up toward the equator, which way will the wind be deflected?

Problem • If a mass of air is moving from 30 degrees north up toward 60 degrees north, which way will the wind be deflected?

Winds create currents

Equinox • Either of two times of year (March 21 and September 22) when the sun and Earth’s positions are such that day and night are exactly 12 hours everywhere on Earth

Warm air holds more water and is less dense than cold air, therefore rain results from the cooling of moist air • High specific heat of water—more heat energy is needed to change the temperature of a given amount of water compared to a given amount of land

Patterns of air movement and temperature influence where wet and dry areas are found

Biomes—major ecological zones corresponding to a climatic zone with a typical vegetation structure, for example, temperate deciduous forest, desert, tropical savanna Biomes are distinct from biogeographic regions

Smaller-scale (regional) patterns of physical factors within the larger patterns • Urban areas are much warmer than surrounding areas within a biome • Mountains influence climate by influencing moisture patterns

Physical factors on a very fine scale • Wind and nest orientation • Temperature will vary above and below ground • Temperature, salinity, and moisture levels all change drastically from low tide to high tide in the intertidal zone

Aquatic environments

Important property of water—water is densest at 4ºC • Ice floats • Warm water stays above cool water • Salty water is denser than less salty water

Thermocline—the boundary layer in the water between surface warmer waters and deeper, cooler waters, where the temperature gradient is greater than that of the warmer layer above and the colder layer below.

Stable in tropics year-round Upper waters are warm, well-lit and oxygen-rich Lower waters are cold, dark, and oxygen-poor Overturn occurs at higher latitudes Oxygen is brought to lower levels and nutrients are brought to upper levels Thermal stratification

Overturn • Vertical mixing of the water column in a lake caused by temperature changes over the seasons

Overturn in temperate lakes means they tend to be quite productive (produce biomass), compared to tropical lakes

Oceans--make up nearly three quarters of the surface of the earth but their boundaries are less clear-cut than those of the landmasses

Differences between terrestrial and oceanic environments • Major oceans are connected, unlike the continents • Water is constantly moving and moves organisms with it • Temperature, light, and other environmental gradients along the horizontal axis tend to change more smoothly and gradually than on land • Depth--environmental gradients may be quite steep along the vertical axis • Plants do not provide physical structure in the oceans

Thermal and solar stratification Anchored plants only near surface Deep water is very cold

Oceanic biomes • Arctic • Subarctic • Northern Temperate • Northern Subtropical • Tropical • Southern Subtropical • Southern Temperate • Subantarctic • Antarctic

Vertical classification of oceanic areas • Continental shelf • Continental slope • Abyssal plain • Trenches

Water circulates horizontally in the oceans • Coriolis effect causes wind patterns which cause currents or gyres. • Current primarily flows clockwise in northern hemisphere and counter-clockwise in southern hemisphere • Continent of Antarctica is enclosed by cold, eastward flowing waters. • Indian Ocean has complex current patterns because of seasonal wind direction shift

Water also circulates vertically in the oceans • In polar regions there is bottom water • In North Atlantic and Pacific, evaporation leads to convergences • Winds and upwelling • Water also rises in areas of divergences

Complete vertical circulation takes 275 years in Atlantic, 250 years in Indian Ocean, and 510 years in Pacific

We know little about marine organisms • Census of marine life • Our knowledge of distributions of marine organisms tends to be more primitive than for terrestrial organisms

Areas of upwellings are areas with rich fisheries

Fishery • A place for catching fish • Also, the occupation, industry, or season of catching fish (or other sea creatures)

Most of the largest fisheries are based on small fish like sardines and anchovies • Nutrient-rich areas (often associated with upwellings) like the coasts of California, Japan, South Africa, Chile, and Argentina have very productive fisheries in some years

The productivity of these fisheries fluctuates dramatically over time • Catches may be huge for a decade or two and then collapse and reappear 1-3 decades later

Global warming and cooling affect productivity, perhaps through affects on food sources • Anchovies eat large zooplankton • Sardines eat small zooplankton and phytoplankton

Differences in mobility affect species’ ability to respond to climate change • Some species of sardines are migratory and can move toward the poles during warmer periods • Some species of anchovies are not as mobile

Hunting pressure also contributes to declines • Anchovies used for human consumption • Anchovies also used to provide fish meal for aquaculture systems

How do we determine distributions of marine organisms? • Example—Mesoplodon spp. or beaked whales

Stranded specimens • Sick animals may not behave normally • Carcasses may be pushed great distances • Identification of carcasses may be difficult

Physical environment comprises temperature, wind, moisture, salinity, pH, fire.