Fundamentals of Ecology Chapter 2 Fundamentals of Ecology © 2006 Thomson-Brooks Cole
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 (physical characteristics of the environment) factors. An organism’s habitat is where it lives, and its niche is the role the organism plays in its community. © 2006 Thomson-Brooks Cole
Key Concepts All organisms expend energy to maintain homeostasis. All organisms expend energy to maintain homeostasis. Physical factors of the environment, such as sunlight, temperature, salinity, exposure, and pressure, will dictate where organisms can live. Species interactions that influence the distribution of organisms in the marine environment include competition, predator-prey relationships, and symbiosis. © 2006 Thomson-Brooks Cole
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. © 2006 Thomson-Brooks Cole
Key Concepts The average amount of energy passed from one trophic level to the next is approximately 10%, and this ultimately regulates and limits the number and biomass of organisms at different trophic levels. With the exception of energy, everything that is required for life is recycled. © 2006 Thomson-Brooks Cole
Study of Ecology Environment Habitat: where an organisms lives Environment biotic factors abiotic factors Habitat: where an organisms lives © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Study of Ecology Niche: an organism’s environmental role Niche: an organism’s environmental role environmental factors biological factors the organism’s behavior © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution Maintaining homeostasis changes in external environment internal adjustments to maintain a stable internal environment homeostasis and the distribution of marine organisms optimal range zones of intolerance © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution Physical environment sunlight photosynthesis vision desiccation temperature ectotherms endotherms © 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution salinity solutes osmosis solutes in the body fluids of organisms tolerance for variation ion environmental salinity regulation of solutes in body fluids © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution pressure 760 mm Hg or 1 atmosphere at sea level increases 1 atmosphere for every 10 meters below sea level © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Environmental Factors 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 © 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution 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 boom-or-bust cycles result from imbalances © 2006 Thomson-Brooks Cole
Environmental Factors Affect Organism Distribution symbiosis: living together mutualism – both organisms benefit from the relationship commensalism – one organism benefits, whereas the other is nether harmed nor benefited parasitism – the parasite lives off the host; the parasite benefits while the host is harmed © 2006 Thomson-Brooks Cole
Populations and Communities Population – a group of the same species that occupies a specified area Community – composed of populations of different species that occupy one habitat at the same time © 2006 Thomson-Brooks Cole
Populations and Communities Population growth there are many ways in which a population can increase in size e.g., recruitment exponential growth logistic growth carrying capacity © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Populations and Communities 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 © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Ecosystems: Basic Units of the Biosphere Examples of ecosystems estuaries salt marshes mangrove swamps rocky shores sandy beaches kelp forests coral reefs open ocean © 2006 Thomson-Brooks Cole
Ecosystems: Basic Units of the Biosphere Energy flow through ecosystems Producers photosynthetic producers chemosynthetic producers © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Ecosystems: Basic Units of the Biosphere Measuring primary productivity rate at which energy-rich food molecules are being produced from inorganic matter light-dark-bottle method measuring carbon in organic products of photosynthesis © 2006 Thomson-Brooks Cole
Ecosystems: Basic Units of the Biosphere Consumers first-order consumers second- and third-order consumers detrivores decomposers Food chains and food webs Other energy pathways dissolved organic matter (DOM) detritus © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Ecosystems: Basic Units of the Biosphere Trophic levels number 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 © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Biogeochemical Cycles Hydrologic cycle water is lost through evaporation returned through precipitation and runoff © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
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 © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole
Biogeochemical Cycles Nitrogen cycle producers use nitrogen to synthesize proteins (amino acids) bacteria recycle nitrogen from wastes and decomposing, dead organisms fixation of atmospheric nitrogen by microorganisms © 2006 Thomson-Brooks Cole
© 2006 Thomson-Brooks Cole