Moodle_Week 2_Friday_Life in Water.pdf

BIOL 2101 Aquatic environments Over 70% of the planet is covered in water​ • 97% ocean​ • 2% glaciers and polar ice caps​ • 1% freshwater​ A diverse set of ecosystems:​ • • • • • • Oceans – deep sea and near shore​ Intertidal zones​ Marshes and swamps​ Rivers​ Lakes​ Peatland Different set of...

BIOL 2101 Aquatic environments Over 70% of the planet is covered in water​ • 97% ocean​ • 2% glaciers and polar ice caps​ • 1% freshwater​ A diverse set of ecosystems:​ • • • • • • Oceans – deep sea and near shore​ Intertidal zones​ Marshes and swamps​ Rivers​ Lakes​ Peatland Different set of challenges How do these environments differ from terrestrial biomes? • Water • Temperature is far more uniform and stable (mostly) • Light • Gravity (less of an issue) • Oxygen is a major limited factors Different set of challenges How do these environments differ from terrestrial biomes? • Water • Temperature is far more uniform and stable (mostly) • Salinity • Light • Gravity (less of an issue) • Pressure • Oxygen is a major limited factors Hydrological cycle • Exchange of water among “reservoirs”​ • Cycle time varies​ • Atmosphere 9 days​ • Rivers 12–20 days​ • Oceans 3,100 years Figure 3.2 The hydrologic cycle (data from Schlesinger 1991 A good reference Open ocean • Open ocean is single interconnected mass, 360 million km2​ • Largest biome • Currents and flow heavily impact both marine and terrestrial life and climate Figure 3.5​ Open ocean: zones Vertical structuring • Intertidal Zone: Shallow shoreline; tidal influence​ • Neritic Zone: Coast to margin of continental shelf.​ • Oceanic Zone: Beyond continental shelf; divided into vertical zones​ • ​Benthic: Habitat on bottom​ • Pelagic: Habitat off the bottom​ Figure 3.6 Open ocean: abiotic factors Light​: Penetration is limited, 80% of solar energy is absorbed in first 10 m, very little penetrates past 600 m.​ Temperature: Warm water floats, generates thermal stratification and thermoclines. ​ Water movements: Winds drive surface currents, upwellings transport water to the surface, facilitate nutrient mixing.​ Salinity: ​Amount of salt dissolved in water, in open ocean is 34 36.5 parts per thousand, varies with ratio of precipitation to evaporation.​ Oxygen: Concentration is highest near ocean surface, and decreases with depth down to ~ 1000 m, then increases again. Open ocean: abiotic factors Light​: Penetration is limited, 80% of solar energy is absorbed in first 10 m, very little penetrates past 600 m.​ Temperature: Warm water floats, generates thermal stratification and thermoclines. ​ Water movements: Winds drive surface currents, upwellings transport water to the surface, facilitate nutrient mixing.​ Salinity: ​Amount of salt dissolved in water, in open ocean is 34 36.5 parts per thousand, varies with ratio of precipitation to evaporation.​ Oxygen: Concentration is highest near ocean surface, and decreases with depth down to ~ 1000 m, then increases again. Open ocean: biotic factors What limits photosynthetic organisms?​ • light – photic zone. ​ Phytoplankton form the base of a food web that supports all oceandwellers - ¼ of all photosynthesis in the biosphere.​ Deep-water organisms are nourished by ocean mixing and chemosynthesis.​ Human influences are increasing – overfishing, oil extraction, garbage. Open ocean: biotic factors What limits photosynthetic organisms?​ • light – photic zone. ​ Phytoplankton form the base of a food web that supports all oceandwellers - ¼ of all photosynthesis in the biosphere.​ Deep-water organisms are nourished by ocean mixing and chemosynthesis.​ Human influences are increasing – overfishing, oil extraction, garbage. Shallow marine waters​ • Highly diverse and productive communities​ • Based on kelp in temperate areas and corals near the equator • Provide habitat with complex structure ​ • Different to open ocean Figure 3.11 (3.12 in 3rd ed) Distribution of kelp forests and coral reefs (data from Barnes and Hughes 1988, after Schumacher 1976).​ Shallow marine waters​ • Kelp forests offer 3-D habitat structure similar to terrestrial forests, can extend >25 m from sea floor​ • Coral reefs can form as barriers, fringes, or atolls – in all cases offer a complex habitat supporting great species diversity. Shallow marine waters: abiotic factors​ Light: Limits kelp growth and development of coral reefs, depth of penetration varies from 10-100 m​ Temperature: Kelp growth (~ 10-20 °C), corals growth and survival (~23-25 °C)​ Water Movements: Currents deliver oxygen and nutrients, remove wastes, productivity influenced by flushing.​ Salinity: Corals require stable salinity, kelps are more tolerant​ Oxygen: Typically, well-oxygenated Shallow marine waters: abiotic factors​ Light: Limits kelp growth and development of coral reefs, depth of penetration varies from 10-100 m​ Temperature: Kelp growth (~ 10-20 °C), corals growth and survival (~23-25 °C)​ Water Movements: Currents deliver oxygen and nutrients, remove wastes, productivity influenced by flushing.​ Salinity: Corals require stable salinity, kelps are more tolerant​ Oxygen: Typically, well-oxygenated Shallow marine waters: biotic factors​ • Coral reefs and kelp forests among the most productive and diverse of ecosystems on earth​ • Both are vulnerable to disruption from uncontrolled predation and human disturbance/exploitation, as well as climate change.​ • Kelp recovers far more rapidly than do coral reefs. Shallow marine maters: biotic factors​ • Coral reefs and kelp forests among the most productive and diverse of ecosystems on earth​ • Both are vulnerable to disruption from uncontrolled predation and human disturbance/exploitation, as well as climate change.​ • Kelp recovers far more rapidly than do coral reefs. Shallow marine waters: biotic factors​ • Coral reefs and kelp forests among the most productive and diverse of ecosystems on earth​ • Both are vulnerable to disruption from uncontrolled predation and human disturbance/exploitation, as well as climate change.​ • Kelp recovers far more rapidly than do coral reefs. Szpak et al. 2013 Intertidal zones​ • Area between high and low tide lines​ • Size depends on the tidal amplitude and angle of incline​ • Can be rocky or sandy/muddy, and varies in exposure – hosts very different communities. Intertidal zonation​ • Duration of exposure to air strongly influences species composition​ • Upper limits of distribution determined by species tolerances, lower by biotic interactions.​ New Zealand Rocky Shore Zonation Intertidal zone: abiotic factors ​ Light: Highly variable depending on exposure and water turbidity Temperature: Great variability, especially when exposed to air and when in tide pools​ Water Movements: Tides are usually semi-diurnal and magnitude varies geographically and with moon phase.​ Salinity: Can be highly variable, especially in tide pools.​ Oxygen: Not typically limiting Intertidal zone: abiotic factors ​ Light: Highly variable depending on exposure and water turbidity Temperature: Great variability, especially when exposed to air and when in tide pools​ Water Movements: Tides are usually semi-diurnal and magnitude varies geographically and with moon phase Salinity: Can be highly variable, especially in tide pools​ Oxygen: Not typically limiting Intertidal zone: biotic factors ​ • Intertidal taxa are well adapted to withstand thermal and desiccation stresses. ​ • On rocky shores, many organisms (e.g. barnacles, mussels, seaweeds) attach to hard substrates; on soft substrates, most are burrowers​ • Competition and predation play important roles in structuring communities. Intertidal zone: biotic factors ​ • Intertidal taxa are well adapted to withstand thermal and desiccation stresses. ​ • On rocky shores, many organisms (e.g. barnacles, mussels, seaweeds) attach to hard substrates; on soft substrates, most are burrowers​ • Competition and predation play important roles in structuring communities. Salt marshes and mangroves ​ • Transitions zones from sea water to land, concentrated along low-lying coast in sandy/muddy areas.​ • Can be associated with estuaries • Where rivers flow into sea – saltwater and freshwater merge (brackish). Figure 3.23 3rd ed (not in 4th or 5th ed). Salt marsh and mangrove forests (data from Chapman 1977, Long and Mason 1983).​ Salt marshes ​ • Salt marshes are periodically inundated as channels fill at high tide. ​ • Salt pans are small basins in marshes that retain water when the tide recedes. • Inland tide pools • Highly productive ecosystems, sensitive to disturbance Mangroves ​ • Tree dominate transition zones • 80 different tree species • Grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate • Mangrove forests stabilize coastlines, reducing erosion from storm surges, currents, waves, and tides and creates complex habitat • Declining due to development Mangroves ​ • Tree dominate transition zones • 80 different tree species • Grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate • Mangrove forests stabilize coastlines, reducing erosion from storm surges, currents, waves, and tides and creates complex habitat • Declining due to development Salt marshes and mangroves: abiotic factors ​ Light: Highly variable from tidal influence and sediment Temperature: Salt marshes variable due to tidal influence and due to solar heating of standing water (e.g. salt pans). Mangroves warm.​ Water Movement: High. Tidal influence can extend up to 200 km​ for salt marshes, whereas mangrove are coastal. Salinity: Depends on tidal inflow and evaporation rates, often stratified both horizontally and vertically​ Oxygen: Highly variable, ranging from very depleted to super-saturated O2 levels Salt marshes and mangroves: abiotic factors ​ Light: Highly variable from tidal influence and sediment Temperature: Salt marshes variable due to tidal influence and due to solar heating of standing water (e.g. salt pans). Mangroves warm.​ Water Movement: High. Tidal influence can extend up to 200 km​ for salt marshes, whereas mangrove are coastal. Salinity: Depends on tidal inflow and evaporation rates, often stratified both horizontally and vertically​ Oxygen: Highly variable, ranging from very depleted to super-saturated O2 levels Salt marshes and mangroves: biotic factors ​ • Plant diversity is limited, but primary production very high​ • Animals are adapted to brackish environments and can withstand environmental fluctuations​ • Extremely important nursery habitat for fish, and critical environment for many birds.​ • Natural sediment traps and water filters, control erosion, prevent flooding – essential habitat​ • Humans have diked marshes to “reclaim” land, removed mangrove, built causeways, and polluted. Restoration is now underway in some areas. Rivers and streams • Rivers drain the landscape, flowing into oceans or interior seas.​ • River basins are areas that are drained by a network of rivers and streams (e.g. Mississippi river basin) • Key terms:​ • • • • Riparian zone​ Benthic zone​ Hyporheic zone​ Phreatic zone Rivers and Streams: abiotic factors Light: Variable depending on riparian shading, presence of organic matter and turbulence Temperature: Typically, 0-30 °C, buffered relative to terrestrial conditions Water movement: Varies from almost still to rapids; can vary seasonally. Clear directionality (upstream processes affect downstream environment) Salinity: Typically low, depends on materials leaching from surrounding environment (e.g., desert) Oxygen: Varies inversely with temperature. Flow rate is also important and input of organic materials and wastes Rivers and Streams: abiotic factors Light: Variable depending on riparian shading, presence of organic matter and turbulence Temperature: Typically, 0-30 °C, buffered relative to terrestrial conditions Water movement: Varies from almost still to rapids; can vary seasonally. Clear directionality (upstream processes affect downstream environment) Salinity: Typically low, depends on materials leaching from surrounding environment (e.g., desert) Oxygen: Varies inversely with temperature. Flow rate is also important and input of organic materials and wastes Rivers and Streams: biotic factors River continuum concept • Downflow effects • Communities change based on abiotic factors (oxygen and temperature), as well as the processing of nutrients Rivers and Streams: biotic factors • Older freshwater bodies – source of species radiation and corridors post-glaciation to the north • Greater diversity in tropical than temperate rivers • Species composition changes as we move downstream • Sediment influences community – soft sediments versus rocky (like intertidal zone) • Humans are incredibly dependent on rivers – irrigation, transportation, energy, food, waste disposal. Yet, we pollute them, dammed them, and introduced species - remediation is a major conservation goal (which ecology informs) Lakes and ponds • Lakes cover 4.6 million km2 area • Most of the world’s freshwater resides in a few large lakes • Great Lakes contain ~20% of fresh surface water in the world Lakes and ponds • Parallels that of oceans, on much smaller scale • Can had river like littoral and riparian zones • Thermocline present in the metalimnion • Less permeant over long timescales • Pond succession Lakes and ponds • Parallels that of oceans, on much smaller scale • Can had river like littoral and riparian zones • Thermocline present in the metalimnion • Less permeant over long timescales • Pond succession Lakes and ponds: abiotic factors Light: Variable depending on depth Temperature: Thermal stratification is common. In winter some lakes freeze solidly, others have only surface ice Water Movement: Wind-driven mixing of the water column is ecologically important, but limited when temperature stratification is present, or when frozen Salinity: Usually very low (except salt lakes) Oxygen: Variable, low in highly eutrophic bodies or at deeper depth Lakes and ponds: abiotic factors Light: Variable depending on depth Temperature: Thermal stratification is common. In winter some lakes freeze solidly, others have only surface ice Water Movement: Wind-driven mixing of the water column is ecologically important, but limited when temperature stratification is present, or when frozen Salinity: Usually very low (except salt lakes) Oxygen: Variable, low in highly eutrophic bodies or at deeper depth Lakes and ponds: abiotic factors Seasonality causes turnover Lakes and ponds: abiotic factors Seasonality causes turnover Lakes and ponds: abiotic factors Light: Variable depending on depth Temperature: Thermal stratification is common. In winter some lakes freeze solidly, others have only surface ice Water Movement: Wind-driven mixing of the water column is ecologically important, but limited when temperature stratification is present, or when frozen Salinity: Usually very low (except salt lakes) Oxygen: Variable, low in highly eutrophic bodies or at deeper depth Lakes and ponds: biotic factors Lakes and ponds: biotic factors Human influence • Overwhelmingly negative – pollution, agricultural runoff, toxic waste, species introductions Peatlands, bogs, and fens • Peatlands occupy >5% of the world’s land, 80% occur at high latitudes. • 15% of Canada is peatland. • Low decomposition of mosses and sedges leads to build up of peat. • Carbon sequestering • Bogs fed by precipitation, fens can be connected to other water bodies. • Bogs have raised hummocks, allowing vascular plant growth. • Fens have standing water and are flat Peatlands, bogs, and fens • Peatlands occupy >5% of the world’s land, 80% occur at high latitudes. • 15% of Canada is peatland. • Low decomposition of mosses and sedges leads to build up of peat. • Carbon sequestering • Bogs fed by precipitation, fens can be connected to other water bodies. • Bogs have raised hummocks, allowing vascular plant growth. • Fens have standing water and are flat Peatlands, bogs, and fens: abiotic factors Light: Typically high, but can vary widely depending on vegetation above and within the water Temperature: Most occur in colder climates, but shallow water can increase temperature and lead to increased decomposition and water evaporation rates Water Movements: Still waters that are stable over time are needed Salinity: Typically low, but pH is critical. Bogs are uniformly acidic (pH < 4.5), while fens vary in pH Oxygen: Anaerobic environment, limits vascular plants, combine with acidity inhibit decomposition Peatlands, bogs, and fens: abiotic factors Light: Typically high, but can vary widely depending on vegetation above and within the water Temperature: Most occur in colder climates, but shallow water can increase temperature and lead to increased decomposition and water evaporation rates Water Movements: Still waters that are stable over time are needed Salinity: Typically low, but pH is critical. Bogs are uniformly acidic (pH < 4.5), while fens vary in pH Oxygen: Anaerobic environment, limits vascular plants, combine with acidity inhibit decomposition Peatlands, bogs, and fens: biotic factors • Dominant moss layer, less acidic and better aerated areas have more diversity of vascular plants. • Carnivorous plants are common – adaptive strategy to meet nitrogen needs • Peat extraction is common and highly destructive - sustainable harvest not possible. • Climate change poses serious challenges for peat lands – effects on carbon stores? Peatlands, bogs, and fens: biotic factors • Dominant moss layer, less acidic and better aerated areas have more diversity of vascular plants. • Carnivorous plants are common – adaptive strategy to meet nitrogen needs • Peat extraction is common and highly destructive - sustainable harvest not possible. • Climate change poses serious challenges for peat lands – effects on carbon stores? Peatlands, bogs, and fens: biotic factors • Dominant moss layer, less acidic and better aerated areas have more diversity of vascular plants. • Carnivorous plants are common – adaptive strategy to meet nitrogen needs • Peat extraction is common and highly destructive - sustainable harvest not possible. • Climate change poses serious challenges for peat lands – effects on carbon stores? Assigned reading: Textbook Chapter 3 • Page 40-62 • Cover most of what we talked about today • Goal is to reinforce the topics we covered