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INTRODUCTION TO ECOLOGY & THE

BIOSPHERECHAPTER 50

Key Concepts:

� Ecology integrates all areas of biological research and informs environmental decision making.

� Interactions between organisms and the environment limit the distribution of species.

� Aquatic biomes are diverse and dynamic systems that cover most of Earth.

� The structure and distribution of terrestrial biomes are controlled by climate and disturbance.

ECOLOGY� Study of the interactions between organisms & the

environment� Subfields:

� Organismal ecology - concerned w/ an organisms’ structure & physiology meet challenges of the environment

� Population ecology - concentrate on factors that affect how many individuals of a species live in an area

� Community ecology - deals w/ the array of interacting species in a community

� Ecosystem ecology - emphasis on energy flow & chemical cycling among living & non living factors

� Landscape ecology - deals w/ the array of ecosystem & how they are arranged in geographic regions

Levels of Ecology

� Biosphere - sum of all the planet’s ecosystems� Ecosystems - all nonliving & living components of

the environment� Communities - all the organisms of all the species

that inhabit a particular area� Populations - group of individuals of the same species

living in a particular area

Organisms & the Environment

� Biotic factors - all the living components of the environment

� Abiotic factors -nonliving components; chemical & physical factors� Temperature, sunlight,

precipitation, pH, salinity

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Factors Affecting the Distribution of Organisms

� Biogeography - study of the past & present distribution of individual species

� Dispersal - distribution of organisms within geographic population boundaries

� Continental drift & barriers contribute to the distinct floral & fauna found in Earth’s major regions

Transplanted Species� Some organisms can

survive in new areas but cannot reproduce

� Cannot determine the success of a transplant until at least one life cycle is completed

� If successful: then potential range of species is larger than its actual range

� If unsuccessful: species cannot survive & reproduce due to biotic or abiotic factors

Examples of Failed Introduced Species

� African Honey Bees - introduced in Brazil to produce more honey; accidentally escaped & have gradually moved into Southern western U.S.; killed 10 people

� Zebra Mussel - native to Caspian Sea in Asia; discovered in Detroit lakes; clogged water intakes for cities; affect food chain by clearing water & allowing bottom rooted plants to increase; feed on phytoplankton which affected zooplankton population

Biotic Factors Affecting Distribution

� Negative interactions with other organisms through disease, predation & competition

� Elimination of a species that introduce species depends upon

Abiotic Factors Affecting Distribution of Species

� Temperature - effects biological processes & inability of most organisms to regulate body temperature

� Water - aquatic organisms must maintain osmotic balance with environment; terrestrial organisms need to prevent dessication

� Sunlight - competition for light by organisms in shade; in aquatic habitats light intensity determines presence of photosynthetic organisms; photoperiod -lengths of daytime & night time

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� Wind - effects temperature by increasing heat loss due to evaporation & convection; contributes to water loss in organisms; inhibit growth of limbs in plants

� Rocks & Soil - physical structure, pH & mineral composition limits distribution of plants & animals that feed on them; can affect water chemistry

Biomes

� Major types of ecosystems characterized by geographic regions, climate and vegetation

� Aquatic biomes account for largest part of biosphere-freshwater(salt < 1%) or marine (salt > 3%)

Freshwater Biomes� Ponds & lakes (standing water), rivers & streams

(moving water)� Littoral zone - shallow areas along shoreline;

light penetration; rooted and floating plants & phytoplankton

� Limnetic zone - well lit open surface waters; primarily algae & phytoplankton; zooplankton, fish, reptiles, & birds; divided into photic (light penetration) and aphotic ( no light)

� Thermocline – area where warm upper layers separate from cold deeper layers.

� Profundal zone - decrease in light penetration� Bentic zone - bottom; no light; detritus

LAKE ZONATION Classification of Lakes

� Oligotrophic� Deep

� Poor nutrient content

� Sparse phytoplankton

� Rocky hard bottoms

� Clear water

� Oxygen rich

� Diverse fish & invertebrate populations

� Eutrophic� Shallow

� Nutrient content high

� Productive phytoplankton

� Silt, clay bottoms

� Murky water

� Oxygen poor

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� Mesotrophic - moderate nutrients & phytoplankton productivity

� Oligotrophic lakes can become mesotrohic & eventually eutrophic - eutrophication

� Rate increase by increase in nitrogen & phosphorous from fertilizer & detergents

� Causes population explosion of algae and detritus and in turn decrease in oxygen

Streams & Rivers

� Nutrient content determined by terrain & vegetation through which water flows

� Leave litter adds organic nutrients while weathering rock contributes to inorganic nutrients

� Turbulence oxygenate water

Wetlands� Area covered with water that supports aquatic

plants� Specially adapted plants called hydrophytes -

grow in water or soil that is periodically anaerobic due to presence of water

� 3 types -swamps, marshes & bogs; determined by topography� Basin wetlands - develop in shallow basins, ranging from

upland depressions to filled-in lakes & pond� Riverine wetlands - develop along shallow & periodically

flooded banks of rivers & streams� Fringe wetlands - occur along the coasts of large lakes & seas

where water flows back & forth rising lake levels or tidal action

Basin Wetland Riverine Wetland

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Fringe Wetland � Riches of biomes

� Support diverse population of organisms

� Provide water storage basins that reduce intensity of flooding

� Improve water quality by filtering pollutants

Estuaries

� Area where freshwater merges with ocean� Bordered by coastal wetlands called mudflats & salt

marshes� Salinity varies spatially & on time of day (tides)� One of most productive biomes due to being enriched

by nutrients of river� Producers - grasses, algae, phytoplankton� Consumers - invertebrates, fish & birds

Zonation in Marine Communties

� Intertidal - area where land meets water

� Alternately submerged & exposed due to tide cycles

� Organisms subjected to availability of saltwater, temperature changes & wave action

� Attach to hard surfaces, borrow in sand

OCEAN ZONATION

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Horizontal Zonation

� Neritic Zone - shallow regions over continental shelf� Contains coral reefs in tropical waters

� Dominated by coral - external calcium carbonate skeleton

� “bleaching” due to high temps

� Oceanic Zone - area extending to continental slope

Vertical Zonation

� Pelagic Zone - open water at any depth� Photic zone

� Aphotic zone

� Benthic zone

� Abyssal zone - area of deep benthic communities; adapted to cold & absence of light; deep sea hydrothermal vents