Chapter 2 Fundamentals of Ecology Karleskint Turner Small

Chapter 2 Fundamentals of Ecology Karleskint Turner Small

Key Concepts • Ecology is the study of relationships among organisms and the interactions of organisms with their environment. • An organism’s environment consists of biotic (biological interactions) and abiotic (non-living, physical) factors. • An organism’s habitat is where it lives, and its niche is the role the organism plays in its community.

Key Concepts • All organisms expend energy to maintain homeostasis, i. e. , internal balance relative to external changes. • Physical factors of the environment, such as sunlight, temperature, salinity, exposure, and pressure, will determine where organisms can live. • Species interactions that influence the distribution of organisms in the marine environment include competition, predation and symbiosis.

Key Concepts • Marine ecosystems consist of interacting communities and their physical environments. • Most populations initially grow at an exponential rate, but as they approach the carrying capacity of the environment, the growth rate levels off. • Energy in ecosystems flows from producers to and through consumers.

Key Concepts • The average amount of energy passed from one trophic level to the next is approximately 10%, limiting the number and biomass of organisms at different trophic levels. • With the exception of energy, everything that is required for life is recycled.

Study of Ecology • Ecology – from the Greek word oikos meaning “home” • Environment – biotic factors – abiotic factors • Habitat: where an organisms lives • Ecosystems – composed of living organisms and their nonliving environment

Study of Ecology • The study of organisms interacting with one another and their environment. This entails: – biological (biotic) factors – environmental (abiotic) factors – the organism’s behavior • Niche: an organism’s environmental role

Higher Species B Niche rs e r Zone of overlap e Food size Si z Larger o pa f s rt ed ic im le s en t Species B Salinity C oa Niche 0 Stepped Art Fig. 2 -12, p. 26

Homeostasis and Distribution of Marine Organisms • Maintaining homeostasis – changes in external environment – internal adjustments to maintain a stable internal environment • optimal range • zones of intolerance

Characteristics of the Physical Environment that Affect Organism Distribution • Sunlight – photosynthesis – vision – desiccation • Temperature – ectotherms – endotherms

Characteristics of the Physical Environment that Affect Organism Distribution • Salinity – solutes – osmosis – solutes in the body fluids of organisms – tolerance for variation environmental salinity – regulation of solutes in body fluids

Cell membrane Outside Inside the cell No net water movement (a) Isotonic solution Cell membrane Outside Inside the cell Net water movement out of the cell (b) Hypertonic solution Net water movement into the cell (c) Hypotonic solution Stepped Art Fig. 2 -4, p. 19

Characteristics of the Physical Environment that Affect Organism Distribution • Pressure – 760 mm Hg or 1 atmosphere at sea level – increases 1 atmosphere for every 10 meters below sea level

Characteristics of the Physical Environment that Affect Organism Distribution • Metabolic requirements – nutrients and limiting nutrients – oxygen as a requirement for metabolism – anaerobic and aerobic organisms – eutrophication and algal bloom • Metabolic wastes – carbon dioxide is a common byproduct of metabolism

Populations • A group of the same species that occupies a specified area • Geographic range • Population size

Distribution of Organisms in a Population • Population density (abundance) • Dispersion – clumped – uniform – random

Changes in Population Size • Can occur through: – reproduction – immigration – death – emigration • Can be affected by: – survivorship – life history – opportunistic and equilibrium species

Population Growth • Many ways a population can increase in size, depending on the carrying capacity of the environment – exponential/logarithmic growth – logistic growth

Population Growth • Density Dependent Factors – have greater effect as population increases in size • Density Independent Factors – not related to population size

Communities • Composed of populations of different species that occupy one habitat at the same time • Niche: what an organism does in its environment – fundamental niche – realized niche

Communities • Biological environment – competition • may be interspecific or intraspecific • may result in competitive exclusion • resource partitioning allows organisms to share a resource – predator-prey relationships • balance of abundance of prey vs. predators • keystone predators

Communities • Symbiosis: living together – mutualism – both organisms benefit – commensalism – one organism benefits, the other is nether harmed nor benefited – parasitism – one organism benefits, the other is harmed

Ecosystems: Basic Units of the Biosphere • Energy flow through ecosystems • Producers = Autotrophs (auto = self, troph = feed) – photosynthetic producers – chemosynthetic producers

Sunlight Chlorophyll Produces 6 Carbon dioxide (CO 2) + 6 Water (H 2 O) Glucose (C 6 H 12 O 6) + 6 Oxygen (O 2) Stepped Art Fig. 2 -16, p. 32

Next: • Find 3 marine animals that are native to California. • Find and describe their ecosystem, community, population, and what each organism is. • Then, list what each level of organization would consist of. • When you are finished, you may put it into a Tellagami and email it to me.

Ecosystems: Basic Units of the Biosphere • Measuring primary productivity – rate at which energy-rich food molecules are being produced from inorganic matter – measuring carbon in organic products of photosynthesis • light-dark-bottle method • radioactive tracers • satellite images

Ecosystems: Basic Units of the Biosphere • Consumers = Heterotrophs (hetero = other, troph = feed) – – first-order consumers second- and third-order consumers detrivores decomposers • Food chains and food webs • Other energy pathways – dissolved organic matter (DOM) – Detritus

Seaweed (producer) Sea urchin (first-order consumer, herbivore) Helmet snail (second-order consumer, carnivore) Fish (third-order consumer, carnivore) Stepped Art Fig. 2 -17, p. 33

Ecosystems: Basic Units of the Biosphere • Trophic levels – number of levels is limited because only a fraction of the energy at one level passes to the next level – ecological efficiency • ten percent rule – trophic pyramids • as energy passed on decreases, so does the number of organisms that can be supported

Biogeochemical Cycles • Hydrologic cycle – water is lost through evaporation – carried north and south from equator – carried west to east within each hemisphere – returned through precipitation and runoff

Moist air Evaporation from rivers, soils, vegetation, lakes, falling precipitation Precipitation Evaporation from ocean Salt Sea spray Runo ff ure Lakes ist o m Soil Ocean Seepage Precipitation Seepage Groundwater Soak in and percolation Land Stepped Art Fig. 2 -20, p. 36

Biogeochemical Cycles • Carbon cycle – carbon released from organisms through respiration and decomposition – recycled by photosynthetic producers – carbon is used in shells, corals and skeletons as part of calcium carbonate – fossil fuels when burned release CO 2 back into atmosphere

CO 2 in atmosphere to plants for photosynthesis CO 2 in the atmosphere Precipitation Respiration Decomposers Limestone Peat Plant residues coal Dissolved CO 2 forms HCO 3– Shells Dissolved CO 2 is taken up by phytoplankton for photosynthesis Decomposition Sediments Limestone Stepped Art Fig. 2 -21, p. 37

Biogeochemical Cycles • Nitrogen cycle – producers use nitrogen to synthesize protein forming amino acids – bacteria recycle nitrogen from wastes and decomposing, dead organisms – fixation of atmospheric nitrogen by microorganisms

Biosphere • Includes all of earth’s communities and ecosystems • Examples of ecosystems: – estuaries – salt marshes – mangrove swamps – rocky and sandy shores – kelp forests – coral reefs – open ocean

Distribution of Marine Communities • Pelagic division – neritic zone and pelagic zone – photic zone, disphotic zone, and aphotic zone – plankton and nekton • Benthic division – shelf zone, bathyal zone, abyssal zone, and hadal zone – epifauna and infauna