MCB 150 Hydroecosphere

• The hydro-ecosphere is the largest of all biomes which covers about 75% of the earth's surface
• Freshwater environment


  Low concentration of dissolved salt
• Marine environment


  High concentration of dissolved salt
• Physical and chemical factors in aquatic environments


  • Light
  • Temperature
  • Flow
  • Pressure
  • Dissolved gases
  • Dissolved solids
• Light


  • Necessary for photosynthesis
  • Affects the growth of microorganisms at varying depths
• Photic zone


  Upper 200 meters where sunlight can penetrate and photosynthesis can take place
• Aphotic zone


  Deeper areas where sunlight cannot penetrate
• As temperature decreases


  Dissolved oxygen availability increases
• As temperature increases


  Dissolved oxygen availability decreases
• Temperature in freshwater environments


  • Highly fluctuating due to precipitation and run-off
• Temperature in marine environments


  • More stable due to ocean currents and global climate patterns
• Thermal stratification in deep lakes

  1. Warm upper layer (epilimnion) does not mix with cool deeper layer (hypolimnion) in summer

  2. Stratification is broken down during cooler seasons when surface layer becomes colder and denser, mixing with bottom layer
• Flow of water


  Influences availability of nutrients, food resources, and water itself
• Pressure


  • Increases by 1 atm for every 10-meter increase in depth, affecting which microorganisms can grow
• pH


  Affected by pollutants, chemicals, bedrock/soil composition, and other compounds
• Acidification of bodies of water


  Results in loss of diversification due to sensitivity of organisms
• Ocean pH


  Averages 8.07, kept basic due to erosion of rocks adding alkalinity, buffered by dissolved CO2, boric acid, silicic acid
• Dissolved gases


  Used by microorganisms and oxygenic organisms like fish and algae in biological processes like respiration and photosynthesis
• Dissolved organic matter in oceans


  Influences production of most marine volatile gases, comes from marine biota like photosynthetic algae and bacteria, consequences of grazing and viral lysis
• Dissolved organic matter in freshwater


  Mostly composed of carbohydrates, aliphatics, and carboxyl-rich alicyclic molecules
• Inorganic substances in oceanic water


  • Cations: Na+, Mg2+, Ca2+, K+
  • Anions: Cl-, SO4 2-
• Inorganic substances in freshwater

  • Ca, Mg, Na, K
• Oligotrophic state


  Clear water, low nutrient concentration
• Mesotrophic state


  Sedimentation of nutrients forms anaerobic zone on bottom
• Eutrophic state


  High nutrient concentration, high presence of organisms, entire body anaerobic except air above
• Types of microorganisms in aquatic environments


  • Resident (naturally occurring)
  • Transient (introduced)
• Transient microorganisms


  Introduced via precipitation, air dispersal, water flow
• Freshwater body types


  • Lotic (flowing): springs, rivers, canals, estuaries, streams
  • Lentic (stagnant): lakes, ponds, wetlands
• Lotic freshwater environments


  • Conditions vary more, harder for microorganisms to inhabit
• Lentic freshwater environments


  • Conditions more stable, higher nutrient concentration and microbial diversity
• Springs and groundwater are mostly oligotrophic and offer little to sustain life, with low microbial numbers
• Microorganisms in lotic freshwater


  • Fecal coliforms: Escherichia coli, Citrobacter, Klebsiella, Enterobacter
  • Salmonella, Proteus, Serratia, Vibrio
• Microorganisms in lentic freshwater


  • Cyanobacteria, Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria
  • Chlorobi, Chloroflexi, Fibrobacteres, Firmicutes, Fusobacteria
  • Micrococcus, Pseudomonas, Bacillus, Sarcina, Flavobacterium, Streptomyces
• Cyanobacteria


  • Autotrophic gram-negative bacteria, primary producers, first to produce oxygen through photosynthesis
• Proteobacteria and Actinobacteria


  • Most abundant in lakes, increase dissolved oxygen
• Archaeal microorganisms in freshwater


  • Euryarchaeota, Crenarchaeota, Thaumarchaeota
• Aquatic fungi


  • Decompose and recycle nutrients, produce extracellular enzymes that target cellulose, pectin, hemicellulose
• Pythium


  • Oomycete that can cause rotting in aquatic plants
• Oceans cover almost 70.8% of the planet's surface and contain 97% of the Earth's water
• Microorganisms found in aquatic environments


  • as
  • Bacillus
  • Sarcina
  • Flavobacterium
  • Streptomyces