"BIOMES AND AQUATIC ECOSYSTEMS"
BIOMES AND AQUATIC ECOSYSTEMS Chapter 44 Learning Objectives What are biomes? What major factors account for their distribution? What is species diversity? Which biomes yield the greatest species diversity? How are the earth’s major terrestrial and aquatic biomes characterized? A. Biomes Major types of terrestrial ecosystems. Distribution of biomes largely depends on climate (temperature & rainfall). Climate is determined by the Earth’s tilt & uneven heating of Earth’s surface. Tilt produces seasons in northern & southern hemispheres. We know that altitude and latitude influence the distribution of biomes …. but how are climatic factors involved? How The Sun Heats The Earth By Radiation Unequal heating causes air movements that distribute moisture. Altitude influences climate - conditions usually become drier & colder as altitude increases. Dry Air Precip. Dry Air Precip. Biomes May be Further Modified By What is Called the “Rain Shadow Effect” Learning Objectives What are biomes? What major factors account for their distribution? What is species diversity? Which biomes yield the greatest species diversity? How are the earth’s major terrestrial and aquatic biomes characterized? Species Diversity What factors contribute to maximum species diversity? Species Diversity What factors contribute to maximum species diversity? Heat Sunlight Water Nutrients Environmental Stability? Species Diversity – H’, has Two Components: Evenness – E --- addresses the equitability of individuals across all species. High evenness increases species diversity. Richness – S --- simply the number of species in a community. The greater the number of species, the greater the diversity. Which Community Has the Greater Diversity, A or B? Community A Community B Sp. 1 – 27 individ. Sp. 1 – 79 individ. Sp. 2 – 18 “ Sp. 2 – 3 “ Sp. 3 – 23 “ Sp. 3 – 8 “ Sp. 4 – 15 “ Sp. 4 – 6 “ Sp. 5 – 17 “ Sp. 5 – 4 “ __________ __________ Total 100 Total 100 Which Community Has the Greater Diversity, A or B? Community A Community B Sp. 1 – 47 individ. Sp. 1 – 57 individ. Sp. 2 – 112 “ Sp. 2 – 43 “ Sp. 3 – 203 “ Sp. 3 – 8 “ Sp. 4 – 65 “ Sp. 4 – 61 “ Sp. 5 – 173 Sp. 5 – 24 “ __________ Sp. 6 – 32 “ Total 600 Sp. 7 – 11 “ __________ Total 236 Remember that the Diversity Index , H’, that you are calculating in your lab exercise incorporates both the evenness (equitability) component and the number of species (richness) component. Are patterns of air circulation (called “Air Coils”) correlated with species diversity within major biomes on a global basis? Yes …… Learning Objectives What are biomes? What major factors account for their distribution? What is species diversity? Which biomes yield the greatest species diversity? How are the earth’s major terrestrial and aquatic biomes characterized? Terrestrial Biomes Tropical Rain Forest Desert Temperate Grassland Temperate Deciduous Forest Taiga or Northern Coniferous Forest Tundra Tropical Rain Forest Biome Tropical Rain Forest warm & moist (rainfall: 79-157 in/yr) nutrients cycle rapidly soils are nutrient poor plants exhibit vertical stratification very high biodiversity Desert Biome Desert dry (rainfall: < 8 in/yr) hot days / cool nights plants adapted to obtain & store water rapid life cycles deep roots (mesquite) succulent tissues / reduced leaves (cacti) animals adapted to minimize water loss tough,waterproof integument concentrated urine nocturnal habits Atriplex (saltbush plant) stores salt in outer cells of leaves. Red vizcacha rat has adaptation that allows it to feed on Atriplex. Temperate Grasslands (prairie) 1 or 2 dry seasons/year (rainfall: 10-40 in/yr) lacktrees & shrubs grazing & frequent fires maintain grass In US, majority of prairie has been replaced by farmland. Temperate Forests rainfall: 26-118 in/yr Temperate forests are either deciduous or coniferous. Temperate Deciduous Forest oak-hickory or beech-maple predominate moist growing season (at least 4 months) soil rich in nutrients vertical stratification organisms adapted to seasonal changes Taiga or Northern Coniferous Forest precipitation falls as snow/ice (8-24 in/yr) long, cold winters soil is thin, moist, acidic & nutrient poor (subsoil may be frozen) biodiversity lower than temperate zone conifers predominate Tundra Biome – A Closer View Tundra Precipitation: 8-24 in/yr long,bitterly cold winters permafrost begins 18 in. below surface low biodiversity shallow-rooted shrubs & lichens plants adapted to short growing season animals adapted to cold (small extremities) & snow (many are camouflaged) Aquatic Biomes (Ecosystems) Freshwater Standing Water – lakes, ponds, bogs, swamps Running Water – streams, rivers Marine – estuaries, mangrove Coastal swamps, intertidal zone, coral reefs Ocean B. Aquatic Ecosystems 1. Freshwater Ecosystems Lakes and Ponds (standing water) littoralzone limnetic zone profundal zone benthic zone Zones Of A Temperate Lake Physical/Chemical Factors Important in Lakes Radiant Energy Permits Photosynthesis Produces Heat Temperature Effects metabolic rates of resident species Influences rate of decomposition Effects water density Physical/Chemical Factors Important in Lakes – Cont’d. Oxygen Influences rate of metabolism Influences rate of decomposition Solubility of O2 in water is effected by temperature and exchange with atmosphere Water Clarity (inverse of turbidity) Effects photosynthesis - and thus food chain Effects heating Operation of O2/Temp and Light Meters Close - Up of Oxygen/Temperature Meter Gary, Can you move to the left a bit? Secchi Disc in action … a simple method for testing water clarity Late April Water Quality Data Surface Waters Starting to Warm Up – Turnover Has Already Occurred Mid September Water Quality Data The Three Layers of a Lake During Summer Stratification Lake Surface Atmosphere Epilimnion – warm, light water Thermocline – boundary layer Hypolimnion – cold, heavy water Lake bottom Temperate Lakes Go Through an Annual Cycle Based on Changes in Climate Over the Four Seasons Annual Cycle Of A Temperate Lake What Are The Consequences of Turnover (i.e. Total Mixing)? O2 gets redistributed throughout the water column. The gases of decomposition get released to the surface of the lake. Nutrients (N,P and K) that accumulated at the bottom due to organisms dying and sinking are released throughout the water column. Review and Summary Oxygen & nutrients (nitrogen/phosphorus) are unevenly distributed in lakes. O2 level is highest near surface nutrient level is highest near bottom Oxygen & nutrients are redistributed by: wind (ponds & shallow lakes) fall & spring turnover (deep lakes in temperate regions) Lake Succession Oligotrophic lakes young; low in nutrients & productivity clear & sparkling blue deep water is oxygen-rich Eutrophic lakes older; nutrient rich & high in productivity green & murky O2 often depleted in deep water during summer Nutrients in sewage & agricultural runoff speed eutrophication. The Process of Eutrophication Defined as the enrichment of a body of water and subsequent increase in productivity. Occurs naturally but at a slow pace over geological time Human activities greatly accelerate the process of eutrophication: Increased nutrient input from fertilizer mismanagement Nutrients associated with sewage Rivers and Streams (running water) Transport rainwater, groundwater, snowmelt & sediment from land to ocean or lake. At headwaters: channel is narrow water is clear & oxygen-rich current is swift At mouth: channel widens water is murky & contains less oxygen current slows, depositing sediment 2. Marine Ecosystems Coastal Ecosystems Include estuaries, mangrove swamps, the intertidal zone & coral reefs. Estuary - area where fresh water of river meets salty water of ocean. water is brackish salinity fluctuates very productive high biodiversity nursery for many ocean animals Salinity Gradient in Estuaries .05 ---------15 ------------ 28 ------------- 32 -----------35 Salinity Values in Parts/Thousand (0/00) Mangrove Swamp – a type of estuary in which a tropical wetland is dominated by salt- tolerant plants (mangroves). transitional zone between forest & ocean salinity fluctuates plants have aerial roots high biodiversity Intertidal Zone - area along coast between high & low tides. organisms adapted to pounding waves & varying degrees of desiccation low productivity Coral Reef - underwater deposits of calcium carbonate formed by colonies of animals. very productive high biodiversity very fragile Ocean Ecosystem covers 71% of Earth’s surface temperature: 35oF - 81oF sunlight quickly dissipates with depth primary producers are photoautotrophs (found near surface) & chemoautotrophs (found at deep-sea hydrothermal vents) highest productivity near upwellings (occurs on western side of continents) Upwellings Warm, light surface water is displaced by strong winds Then, colder, nutrient-rich water is able to rise to the surface from the aphotic zone of the ocean Thus, algal productivity and the entire epilimnetic food chain is greatly enriched Finis