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Transcript
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 • Its “job” in the environment 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 • Organisms might be limited as to where there is sunlight: – For photosynthesis – For vision • Organisms might be limited to location by temperature – ectotherms – endotherms Characteristics of the Physical Environment that Affect Organism Distribution • Organisms might be limited to where they can live by salinity –Some can withstand higher salinity than others Characteristics of the Physical Environment that Affect Organism Distribution • Some organisms are limited to location by pressure –760 mm Hg or 1 atmosphere at sea level –increases 1 atmosphere for every 10 meters below sea level –Deep sea animals are adapted to living at high pressure 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 » For example, the lagoon, open ocean, deep sea, etc. – 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 – What all that species could do in the environment – realized niche – Species are going to be limited by other species in the area that might have similar niches 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 – Zones according to location to land: • neritic zone (nearshore) and pelagic zone (open ocean) – Zones according to light penetration: • 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 – Organisms that live in the pelagic: • Plankton (organisms that float) and nekton (organisms that swim) • Benthic division – Bottom sediment area: • shelf zone, bathyal zone, abyssal zone, and hadal zone – Organisms that live in the benthic zone are divided into: • Epifauna (organisms that live on top of sediment) and infauna (organisms that live in the sediment)