estuaries fresh & salt meet
DESCRIPTION
Estuaries fresh & salt meet. Tremendously Productive DETRITUS. Origin and Types. Drowned river valleys or coastal plain estuaries Bar-built estuary Tectonic estuary Fjords. Drowned or Coastal Plain. 18K yr last ice age Chesapeake Bay, Delware and St Lawrence, Thames. Bar-built Estuary. - PowerPoint PPT PresentationTRANSCRIPT
Estuariesfresh & salt meet
Tremendously Productive
DETRITUS
Origin and Types
• Drowned river valleys or coastal plain estuaries
• Bar-built estuary
• Tectonic estuary
• Fjords
Drowned or Coastal Plain
• 18K yr last ice age
• Chesapeake Bay, Delware and St Lawrence, Thames
Bar-built Estuary
• Sand bars and barrier islands
• Barrier between ocean and river’s freshwater
• Texas coast, N. Carolina coast, N. Sea coast
Tetonic Estuaries
• Land subsided from crust’s movements
• San Francisco Bay
Fjords
• Cut by retreating glaciers• Steep wall• Alaska• Norway• Chile• New Zealand
The bodyDiversity
Adaptations
Invertebrate Classification & Relationships10
Classification by Developmental Pattern
• Multicellular animals have been divided into two groups based on the # of germ layers– Germ layer
• Diploblastic– Ectoderm– Endoderm
• Triploblastic – Mesoderm
Most metazoans are triploblastic
Invertebrate Classification & Relationships11
Different Developmental Types
Triploblastic
Acoelomate Pseudocoelomate Coelomates
Protostomes Deutrostomes
Invertebrate Classification & Relationships12
Classification by Developmental Pattern
• Triploblastic animals can be classified even further
AcoelomatePseudocoelomate
Coelomate
Body Plans Provide Diversity
• A Question of Adaptation• Often – Consumer and Consumed Co-Evolve• Driver of Speciation – Exploitation of New Energy
Resources• Topics on the diversity of higher organisms
– Anatomy• Skin – keeps the body intact, etc.• Jaws –respiration and feeding• Appendages – locomotion and buoyancy
– Cardiovascular system– Respiratory system
Energy Budgets
Intake ( I = Income)• Macronutrients
– Carbohydrates– Fats/Oils– Proteins
• Micronutrients– Vitamins– Essential
• Fatty Acids• Amino Acids• Sugars
Energy Use (E = Expenditure)• Respiration• Osmoregulation• Movement• Feeding• Digestion
• Reproduction
IFI = E Growth = 0I < E Growth = I > E Growth = +
Keystone System Circulatory system
Plausible Scenarios• Ancestor chordates evolved in an isotonic setting
– All were marine since the start
• No osmotic gradients• No energy required for osmoregulation• Body surface was highly permeable• Some ion regulation• Kidneys were exclusively for excretion• When early vertebrates invaded freshwater
– Osmotic disruption resulting in excess water• Absorption through thin epithelium• Water intake from feeding
• Need to solve this problem along with ion balance
Osmosis is the tendency of water to move between two solutions of different osmolarity separated by a barrier permeable for water (e.g. membrane).
Living organisms
• an aqueous solution with solutes contained within a series of membrane system
• volume [solutes] maintained within a narrow limits for the optimal function
• deviations from physiological composition: incompatible with life
• maintain the proper concentrations of body fluid which invariably differ from the environment
• unlike cell walls of plants, the animal cellular plasma membrane is not equipped to deal with high pressure differences or large volume changes
Osmoregulation: ability to hold constant total electrolyte and water content of the cells.
Critical for survival and success
Concepts of osmorality
• Osmotic concentration of a solution can be expressed as osmorality (osmoles per liter)
• Concentration of a dissolved substance is expressed in units of molarity (number of moles per liter solution)
• Osmorality of a nonelectrolyte (sucrose) equals the molar concentration: 1M = 1 Osm per liter
• Osmorality of an electrolyte (NaCl) has a “higher” osmorality because of ionic dissociation and hence exerts a “higher” osmotic force– Not exactly because concentration and the interactions
between ionic charges with water can influence the system
– Along with the low osmotic coefficient of NaCl (Φ = 0.91)
• Osmotic concentration determined by – measuring freezing point depression– vapor pressure of the solution– Seawater osmotic concentration: 1000 mOsm
• 470 mmol Na & 550 mmol Cl
Two categories of osmotic exchange
Obligatory
has little control such as trans-epithelial diffusion, ingestion, defecation, metabolic water production
Regulatedphysiologically controlled and help maintain
homeostasis (active transport)
Two Strategies to minimize this problem
• Decrease the concentration gradient between animal to environment
• Lower the permeability to the outside in areas that are compromised (gills, gut)
Even so
• Always some diffusive leaks• For a counter-flow system to equal this leak
– needs energy– Osmoregulators spend 5% to 30% of their metabolism in
maintaining osmotic balance
• Highly variable aquatic environment – Freshwater– Brackish water– Seawater– Hypersaline water (Med )– Soft water runoffs
• Euryhaline:
• Stenohaline:
• isomotic:
• osmoconformer:
• osmoregulator:
Four groups of regulation dealing with water in fishes
• Hagfish
• Marine elasmobranchs
• Marine teleosts
• Freshwater teleosts and elasmobranchs
Five groups of regulation dealing with ions in fishes
• Hagfish
• Marine elasmobranchs
• Marine teleosts and lampreys
• Freshwater teleosts
• Euryhaline and diadromous teleosts
Aganthans
• Lampreys live in sea and freshwater but hagfish are strictly marine
• Both employ different solution to life in the sea
Hagfish
• Are the only true vertebrates whose body fluids have salt concentration similar to seawater
• Have pronounced ionic regulation
Lamprey
• Egg & larvae develop in fresh water
• Some species stay, some migrate to sea
• Adults return to breed (anadromous fish)
• Osmotic concentration about 1/4 to 1/3 of the seawater
• Face similar problems to that of the teleosts
Marine Elasmobranchs & Holocephalans
• [Salt] at about 1/3 of seawater
• Osmotic equilibrium achieved by the addition of large amount of organic compounds– primarily urea (0.4M)– various methylamine substances
• 2 urea :1 TMAO
• trimethylamine (TMAO), sarcosine, betaine, etc.
• Blood osmotic concentration slightly greater than seawater
• Water is taken up across the gills, which is used to remove excess urea via urine formation
• Small osmotic load for the gills• Urea and TMAO are efficiently reabsorbed
by the kidneys
But
• Urea disrupts, denatured, cause conformational changes in proteins, collagen, hemoglobin, and many enzymes
• Some elasmobranch proteins are resistance to urea• Yancey & Somero (1979):
– Proteins are actually protected by the presence of TMAO
– found to have a consistent ratio of 2 urea to 1 TMAO (also in Holocephalan and Latimeria)
Neat invention
• Strategy of using waste products as an economical way for osmoregulation; unlike the invertebrates which invest on free amino acids to increase serum osmorality
• ionic composition is different from seawater, hence still need to spend energy for ionic regulation
• Need to have the ornithine-urea cycle
Freshwater elasmobranchs
• sawfish, bull shark (C. leucas), stingrays are euryhaline– live in brackish and even freshwater for long
time (Bull in Lake Nicaragua, Mississippi rivers)
• Urea (25-35%), sodium, and chloride are reduced as compared to sw counterparts
• produce copious flow of dilute urine to deal with the water influx
• In freshwater rays, they abandoned urea retention, and reduced ionic content to cope with this problem
• These freshwater rays are not able to make urea when presented in seawater
Coelacanth
• Blood composition is similar to the marine elasmobranchs
• Total osmorality is less than seawater• This maybe due to the habitats they live in:
aquifers feeding into the caves and fissures that could presumably lower salinity: hence a localized hyperosmotic to the surrounding????
Teleost Fish
• Maintain osmotic concentration at about 1/4 to 1/3 of seawater
• Marine teleosts have a somewhat higher blood osmotic concentration
• Some teleosts can tolerate wide range of salinities• Some move between fresh and salt water and are
associated with life cycle (salmon, eel, lamprey, etc)
Marine teleosts
• Hyposmotic, constant danger of losing water to surrounding via the gill surfaces
• Compensate for water loss by drinking• Salts are ingested in the process of drinking• Gain water by excreting salt in higher
concentration along the length of its convoluted tubules
• Produce small amount but very concentrated urine– 2.5 ml/kg body mass/day
• Kidney cannot produce urine that is more concentrated than the blood
• Need special organ, the gills
• Active transport requires energy
• Water loss from gill membrane and urine
• Fish drink to balance the water deficits
• Na and Cl secreted via the gill’s chloride cells
• Gut: for elimination of divalent salts