Transcript Document
Aquatic Biomes Aquatic Biomes • Marine – Ocean – Estuary • Fresh Water – Rivers and Streams (Lotic) – Lakes and Ponds (Lentic) Continental Shelf – the portion of the continental plate that lies submerged under the ocean. –Usually has a gentle slope –Width can vary from a few to ten kilometers Continental Slope – that area that drops from the continental shelf to the full depth of the ocean floor. Oceans Oceans Oceanic zone – any portion of the ocean beyond the continental shelf. Neritic zone – section of ocean that lies over the continental shelf. Littoral zone – shoreline between the high and low tide marks. Oceans Photic Zone – area of water that sunlight penetrates Aphotic zone – area of water that sunlight does not penetrate Oceans Thermocline – vertical area where temperature abruptly changes; restricts the mixing of upper and lower water masses. Oceans • Salinity averages 35 ppt (full strength sea water). – Due to high concentrations of sodium and chloride • Ocean is more than salt and water, but most ocean waters are very poor in nutrients – Phosphate, nitrate, ammonium, iron • Oceans cover ~71% of Earth, but only account for 50% of the Earth’s primary production. – Biological deserts not limited by water, but by nutrients – Unlike terrestrial biomes, production is not higher at equator and lower at the tropics –respond to nutrient concentrations like upwellings. Oceans • Coastal regions are much more productive than non-coastal areas. – Rich nutrient input from coastal rivers – Most of the worlds great fisheries come from the continental shelf – Too many nutrients can lead to algal blooms, which may deoxygenate the water (eutrophication) Some Fish Life History • Anadromous – fish that spend their adult life in salt water but spawn in freshwater – Salmon, striped bass, American shad • Catadromous – fish that spend their adult life in freshwater but spawn in saltwater – American eel Sargasso Sea Ocean Benthic Zone • Benthic zone is the ocean bottom – a thick blanket of mud that consists of fine particles that have settled from the overlying water and accumulated over millions of years. • Scientists originally thought that life could not exist in the benthic zone. – Too much pressure, too dark, too cold, lack of food • We now know that there is a lot of life down there. Chemoautotrophic Organisms • Photosynthetic organisms are labeled as autotrophs, specifically phototrophs. • Organisms that are able to harvest energy from inorganic compounds without photosynthesis are called chemoautotrophs. – Usually sulfur-oxidizing (harvesting energy rich electrons from sulfur compounds) organisms Chemosynthetic Communities Organisms use organic material seeping from the ocean floor as an energy source Colorful crab perched on top of a large tubeworm cluster at GC 354, depth 532 m. This community was first discovered on this MMS/LSU subdive, August 24, 2000 http://www.gomr.mms.gov/homepg/regulate/environ/chemo/chemo.html Symbiotic Relationships • Consumer organisms found in chemosynthetic communities rely on a symbiotic relationship with chemoautotrophic bacteria. • Consumer organisms must take up inorganic carbon (CO2) and sulfides and get rid of the bacterial waste. • The bacteria are able to capture energy (oxidize) from the sulfides to reduce carbon dioxide (primary production). – Consumers then absorb nutrients from the bacteria! • Consumer organisms do not have a mouth or gut! Estuaries • Where the river meets the sea – Sometimes classified freshwater, sometimes classified marine • Most productive biome on Earth • Support a diverse fauna including a variety of worms, oysters, crabs, and waterfowl. • Serve as nursery habitat for many organisms. Marsh Types • Fresh water marsh salinity < 1.0 ppt. – Plants are not salt tolerant and include maidencane, bulltongue, alligatorweed, cattails, and spikerush • Intermediate marsh salinity averages 3.3 ppt. – Plants are slightly salt tolerant and include spikerush, threecorner grass, arrowhead, cordgrass, wiregrass, roseau cane, and deer pea • Brackish marsh salinity averages about 8 ppt. – typically dominated by cordgrass or wiregrass • Salt marsh salinity averages about 16 ppt. – oyster grass is common, but few other plant species can survive Freshwater Marsh Brackish Marsh Intermediate Marsh Salt Marsh Rivers and Streams • Generally represent the excess of precipitation on land areas over evaporation from them. – Precipitation that falls is either evaporated, transpirated, enters the ground water supply, or flows down rivers • Flow is down-hill and varies seasonally – Related to rainfall and ice/snow melt • Beginning of a river = the source and the end of a river = the mouth • Discharge - volume of water passing a given point during a period of time – Channel Width X Depth X Velocity Rivers and Streams • Flow velocity is important in determining abiotic and biotic components. – Flow related to slope and precipitation – Sediment type, current strength – Only certain organisms can withstand strong flow – The faster the flow, the more material can be transported in the water • Materials are transported by running water in three principal states – Dissolved matter – Suspended solids – Bed load Stream Order Used to classify a stream in relation to tributaries, drainage area, total length, and age of water. 11=2 12=2 22=3 13=3 23=3 1 1 1 1 2 2 1 33=4 Mississippi River is classified as a 10th or 12th order stream. Headwater stream classification Stream Order – Strahler Method matters 3 2 Major Rivers of The World Discharge 103 m3/sec Length 103 km Drainage Area 106 km2 Amazon, South America 212.40 6.44 5.78 Congo, Africa 39.65 4.70 4.01 Ganges-Brahmaputra, India 38.50 2.90 1.62 Yangtze, China 21.81 5.98 1.94 Yenisei, USSR 17.39 5.54 2.59 Mississippi North, America 17.30 6.02 3.22 Mekong, Asia 11.04 4.00 0.80 Nile, Africa 3.10 6.65 3.35 Name You will be required to draw a map of the major rivers of the Mississippi River Basin as part of exam 1. Distributary – A smaller channel that takes water away from the main stem river. Flow Mississippi River (Main Stem) Atchafalaya River (Distributary) River Channel Deep Holes Sand Bars Oxbow Formation Lakes and Ponds Ponds – light can reach the entire bottom Lakes – light can not reach some parts of the bottom Lake Overturn Epilimnion Hypolimnion Thermocline 22˚ 20˚ 18˚ 8˚ 6˚ 5˚ 4˚C 4˚ 4˚ 4˚ 4˚ 4˚C Summer Fall overturn 2˚ 4˚ 4˚ 4˚ 0˚ 4˚ 4˚ 4˚ 4˚ 4˚C 4˚C Winter Dissolved O2 concentration 4˚ Spring overturn High Medium Low 4˚