Ecology Adaptation to Aquatic Environments

How is density of water different from other substances? At what temp does it change? Effects of that?

Ice less dense than water. @ 4 degrees C distance between molecules expand. This is why ice floats on water. Also how ice insulates water.

Give 3 examples of adaptations aquatic organisms made to not sink. Why is it needed?

1. Large flat leaves of water lily.

2. Fats and oils within organism

3. Swim bladder (air pocket)

Needed because organisms are made of dense things, like bone and proteins and would sink otherwise.

What is viscosity? What does higher viscosity mean? What does lower viscosity mean?

Viscosity is resistance to movement. Higher viscosity means more resistant to movement.

Give 2 examples on how animals made adaptations to counter water’s viscosity

1. Some animals convergently evolved into a streamlines shape (ex. dolphins, sharks, whales)

2. Other organisms evolved long filamentous appendages to increase drag (like parachute)

What are 2 effects of deep water?

1. Deep water = more pressure → many aquatic animals lack air or have collapsible air cavities

2. Less light = less photosynthesis.

What is the depth limit for photosynthesis?

100m (it has 1% of the light found at the surface)

How do autotrophic organisms survive in deep water? Where?

They use chemosynthesis (use chemical energy to make food). Usually near hydrothermal vents

What is another way deep dark water species survive.

They have their own light (ex. female anglerfish). The light attracts prey and mates. Anglerfish do not make their own light, they have a mutualistic relationship with bioluminescent creatures.

How does the polarity of water enable chemical reactions?

Since water is polar it attracts other polar compounds. So when rain hits rock and soil when it hits land, it picks up the minerals and dissolves it as it flows into bigger bodies of water. Minerals are dissolved until the water is saturated.

What is osmoregulation?

The process in which organisms maintain the correct amount of fluids and dissolved solutes in their body.

What are hyperosmotic organisms? Where do they live? What is their main challenge?

They are organisms that have a higher concentration of solute in their tissues than their environment. They face the challenge of water trying to get into their tissues and solute trying to leave. They live in freshwater.

Features of organisms with hyperosmoregulation (How do get they water, what is their urine like, what do their gills do?

1. They gain water from their food and osmotic influx

2. Their urine is dilute, lots of water is released and their kidneys try to keep the solute in their body

3. Their gills take in Na+ and Cl- from water

What are hypoosmotic organisms? Where do they live? What is their main challenge?

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They are organisms that have a higher concentration of solute in the water than in their tissues. They face the challenge of trying to keep water in their tissues. They live in saltwater.

Features of organisms with hypoosmoregulation (How do they get water, what is their urine like, what do their gills do?

1. They drink lots of water

2. Their urine is concentrated (so they can retain water)

3. Gills transport solute out of fish

How do sharks/rays handle osmoregulation?

Most aquatic organisms directly excrete urea. On the other hand, sharks and rays convert ammonia to urea, but do NOT excrete all of it in order to raise the concentration in their bloodstream to about 2.5%. This raises osmotic potential but not Na+ or Cl- ion levels. They do not need to drink saltwater to replace water lost my osmosis.

What is an adaptation sharks/rays have to go through as a result of their urea adaptations?

They have high amounts of trimethylamine oxide to protect their proteins from urea. Freshwater rays do not accumulate urea.

How is the great salt lake challenging for organisms? What organisms adapted? How?

1. Very high salt content (8-27%) (8x saltier than sea water)

2. brine shrimp excrete salt at very high rates, but high energetic cost. Feed on photosynthetic bacteria as energy source.

What is freshwater salinization? Why is it happening?

Freshwater salinization is the increased salt concentration in freshwater. This is happening because of human activity. the use of road salt has increased 100 fold in less than 200 years. The salt moves with runoff and into freshwater.

What did Nancy Karraker and colleagues find when they tested concentrations of road salt in wetlands various distances from salt-treated road

They found that Wetlands close to the road had a 0.12% increase in salt. Just 200m there was barely any salt increase.

Effect of salt exposure on larval wood frogs and spotted salamanders? Why?

Salt increase caused significant death in larvae of both species. Both species were not exposed to salt in evolutionary history.

What are the essential gasses aquatic organisms needed to adapt in order to get.

Oxygen and Carbon Dioxide

Why is carbon dioxide necessary?

Essential for photosynthesis of aquatic plants and algae

How does carbon dioxide react with water. What about in high concentrations?

It is soluble. Its molecules combine with water to form carbonic acid. In high concentrations, it can provide the carbon needed for photosynthesis.

How does carbonic acid (H₂CO₃) react with water?

Depending on the pH of water it might release H+ ions to form either Carbonate (CO₃^2-) or Bicarbonate (HCO₃^-). In acidic water, CO₂ is more common. In moderate pH water both carbonate and bicarbonate and present, but bicarbonate is favored.

How do plants/algae react to different amounts of HCO₃ and CO₃

1. In acidic conditions, some species can only use CO₂ for photosynthesis

2. In moderate pH conditions, plants can use both by converting bicarbonate to carbon dioxide.

Plants can also release H+ into water, driving the reaction that turns bicarbonate to carbon dioxide.

What is the boundary layer of a plant? How does it affect their photosynthesis?

The boundary layer of a plant is a layer of unstirred water around a plant. The amount of CO₂ and HCO₃ in that layer is depleted because the plant uses it. There is a slow replacement of that inorganic carbon, so photosynthesis is limited to the amount of carbon in the boundary layer.

How does O₂ act in water (Solubility and Diffusion?) How does that affect aquatic organisms?

Compared to CO₂, water has a very low solubility. Ot also has a very slow diffusion. This makes it hard for organisms that need O₂ for their metabolism (Although this isn’t include whales who can get it from air). Organisms that respire aerobically in deep water face challenges because they do not receive O₂ from photosynthesis.

How do gills help aquatic organisms who need O₂?

Water passes over Gills → O₂ diffuses across membrane of gill cells → O₂ enters capillaries

What is countercurrent and concurrent circulation? Who uses it?

Countercurrent circulation is when two fluids on their side of a barrier move in opposite directions. Concurrent circulation is when they move in the same direction. Gills use countercurrent circulation because the blood in the gills move in different directions than the water. This makes sure that there is always more Oxygen in the water than in the blood, so O₂ will always diffuse into the organism and not out of.

How do organisms in Low O₂ environments reduce the need for O₂?

They have low rates of activity

What adaptation do zooplanktons have to increase O₂?

They increase the amount of hemoglobin in their body. This increases the amount of O₂ their body can carry. It also turns their transparent bodies red.

how have tadpoles and some fish adapted to low O_2?

They swim to the surface of the waterbody and take gulps of air. Tadpoles have primitive gills and lungs. Fish store the O₂ in their swim bladder. The gills extract the O₂ in the bloodstream.

What is the relationship between North American Salamanders and Algae?

They have a mutualistic relationship. The salamanders eggs are attached to sticks and submerged in water. The egg sacs provide algae a place to live and the developing embryos receive O₂ from the photosynthesis of the algae. Recently it was found that algae live IN the embryo and provide sugars to the embryo. They get nutrients from the embryos waste.

What is the relationship between sea slugs and algae?

They have a mutualistic relationship. Once sea slugs hatch, they consume algae and then isolate some of their chloroplasts. Eventually they do this enough to turn green and photosynthesize to meet their energy needs.

What are homeotherms?

Organisms that maintain a constant body temperature. They do this through homeostasis.

What are poikilotherms?

Organisms that do not have a consistent body temperature. Ex. frogs, snakes

What are heterotherms?

The body temperature of an organism is sometimes maintained to be constant and other times a result of their environment. Ex. Hummingbirds, bats, bees

What are ectotherms? What are some features of ectotherms?

1. Organisms whose body temperature is determined by external environment (Ex. reptiles, plants, and insects).

2. They have a low metabolic rate or small body size. They cannot generate enough heat to offset heat loss from their environment. They balance heat through changes in their behavior,

What are endotherms? What are some features of endotherms?

1. Organisms who generate enough metabolic heat to raise their body temperature higher than their external environment

2. They are mammals. They require a lot of energy. It accelerates biological activity in colder climates.

What is thermal optimum?

The temperature at which an organism preforms its best. Most organisms can tolerate very little more heat than this point since proteins and other molecules are less stable or denature.

What are thermophilic organisms? What characteristics do they have to do this?

1. Unlike most organisms, who cannot survive over 45 degrees C, thermophilic organisms (mostly bacteria) are “heat loving” and can tolerate extreme heat. An example of this is Archaebacteria, who can tolerate temps over 110 degrees C.

2. They do this having more ionic bonds for stability and a hydrophobic interior that is tightly packed and resists unfolding. They also have specific amino acids that increases stability (ex. proline)

How does thermal pollution impact a species thermal optima? What is that called?

Nuclear power plants use nearby water for cooling. They return the water at a much higher temperature than when they got it. Organisms are not adapted to those temperatures and die. That is called thermal pollution?

How do organisms adapt to avoid freezing?

1. maintaining bod temp above freezing point

2. Activating chemical pathways to resist or tolerate freezing

How do skipjack and bluefin tuna tolerate low temps?

Generate heat through

1. swimming muscles during sustained swimming (fast swimming also helps catch/evade)

2. countercurrent blood circulation

Why are marine vertebrae more susceptible to freezing in sea water? How is that combatted? Who uses that method?

In sea water, an organisms blood is less salty than the water around it. This means it is more prone to freezing (higher freezing point). A way to combat this is to raise the concentrations of non-salt compounds, like glycerol, which prevents formation is H bonds in water. Antarctic fish use this method.

What are glycoproteins?

Protiens that act as antifreeze and can lower freezing temp in body. They bind to ice crystals and prevent them from growing larger, allowing arctic fish remain active in water.

Do temps in cold environments fluctuate often?

No