Transcript Chapter 2
Who, What, When, Where, Why, and How of Marine Ecology • Who studies marine-life habitat, populations, and interactions among organisms and the surrounding environment including their abiotic and biotic factors? • What factors contribute to the distribution of marine organisms in their environment? • When do temperature changes affect communities? • Where is the benthic zone? • Why are trophic pyramids important to Marine Ecologists? • How are heterotrophs related to autotrophs? Chapter 2 Fundamentals of Ecology Karleskint Turner Small Marine Ecology • Marine Ecology is the scientific study of marine-life habitat, populations, and interactions among organisms and the surrounding environment including their • abiotic factors - non-living physical and chemical factors that affect the ability of organisms to survive and reproduce and • biotic factors - living things or the materials that directly or indirectly affect an organism in its environment Study of Ecology • Ecology – from the Greek word oikos meaning “home” • Environment – biotic factors (living) – abiotic factors (non-living) • 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 Homeostasis and Distribution of Marine Organisms • Maintaining homeostasis – changes in external environment – internal adjustments to maintain a stable internal environment • optimal range » For example, we have optimum temperature (98.6), pH, etc. • 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 in solution –osmosis –solutes in the body fluids of organisms –tolerance for variation ion environmental salinity –regulation of solutes in body fluids 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 cell respiration – Anaerobic organisms – don’t need oxygen – aerobic organisms – do need oxygen –Excess nutrients can result in eutrophication and algal bloom • Metabolic wastes –carbon dioxide is a common byproduct of metabolism • As a review: – Physical characteristics of the environment will effect organism distribution – – – – – – Temperature pH Salinity Sunlight Pressure Nutrient availability (oxygen, nitrates, phosphates, etc) • Individuals • Population – group of individuals of same species • Community – different species living together • Ecosystem – community plus abiotic factors 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 Exponential growth Logistic growth 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 – Convert energy from the sun and harness it into organic molecules that will make their way up the food chain • Photosynthetic producers – some bacteria, algae, plants » Majority of primary producers on the planet • Chemosynthetic producers – some bacteria that live in hydrothermal vents » Do not use energy from sun, instead use energy from inorganic molecules being released from hydrothermal vents at bottom of the ocean Ecosystems: Basic Units of the Biosphere • Consumers = Heterotrophs – hetero = other, troph = feed – Different levels of consumers: • first-order consumers (herbivores) • second- and third-order consumers (omnivores and carnivores) • detrivores • decomposers • Food chains and food webs 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 Biogeochemical Cycles • Carbon cycle – Cellular respiration – carbon released from organisms through respiration and decomposition – That’s why we breathe out CO2 – Photosynthesis – The carbon in CO2 isrecycled by photosynthetic producers – carbon is used in shells, corals and skeletons as part of calcium carbonate – fossil fuels, when burned, release CO2 back into atmosphere Biogeochemical Cycles • Nitrogen cycle – fixation of atmospheric nitrogen by microorganisms that have symbiotic relationship with plants – Producers (plants) use nitrogen to synthesize amino acids to form proteins – Other organisms eat those producers, to form their own proteins, nitrogen makes it’s way up the food chain – bacteria recycle nitrogen from wastes and decomposing, dead organisms 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 (nearshore) and pelagic zone (open ocean) – photic zone (light), disphotic zone (little light), and aphotic zone (no light, majority of the ocean) – Majority of the biomass of ocean is in photic zone – Plankton (organisms that float) and nekton (organisms that swim) • Benthic division – shelf zone, bathyal zone, abyssal zone, and hadal zone – Epifauna (organisms that live on top of sediment) and infauna (organisms that live in the sediment)