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Geosc 040 Quiz 2 Study Guide
Terms in this set (37)
Fish, such as eels, live in fresh water to grow and then migrate to salt water to breed
Fish, such as salmon, live in salt water to grow and feed and then return to fresh water to breed and spawn
Lateral line organs:
Used to detect movement, vibration, and pressure gradients in the surrounding water in fish that help them navigate the waters
What factors make a sustainable, commercial fishery; that is, what types of fishes can be harvested in a sustainable fashion?
-Sustainable fishery is that it is one that is harvested at a sustainable rate, where the fish population does not decline over time because of fishing practices.
-Overfishing, habitat destruction, and global warming are among the factors leading to the loss of fish.
-Fish with long life spans are not a sustainable fishery resource because of their slow reproductive rates
What is aquaculture and what are some of the pros and cons of aquaculture as it is practiced today?
=the breeding, rearing, and harvesting of plants and animals in all types of water environments including ponds, rivers, lakes, and the ocean.
Pros: a potential solution to over fishing: less pressure on wild ecosystems, easily accessible, allows wild systems to replenish, pollution more concentrated, less spread out
Cons: there are problems that need to be addressed, such as: overcrowding and transfer of disease and parasites, polluted water systems, messed up gene pool if native and farmed species interbreed.
How do Coral live? Are the shells alive? What are the key factors in the 'energy flow' of a Coral reef?
Corals need to grow in clear, shallow water where sunlight can reach them
Modern coral reefs appear to be limited to regions where the mean annual temp is > 20 C
Corals consume phytoplankton and other simple photosynthetic organisms. They depend on the zooxanthellae (algae) that grow inside of them for oxygen and other things, and since these algae needs sunlight to survive, corals also need sunlight to survive
Corals rarely develop in water deeper than 165 feet
Reefs begin when a polyp attaches itself to a rock on the sea floor, then divides, or buds, into thousands of clones.
What are coral polyps and what do they eat?
Coral polyps are tiny, soft-bodied organisms related to sea anemones and jellyfish. Their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs.
They mainly emerge at night to feed & precipitate CaCO3
They can extrude their guts to attack nearest neighbors competing for space
They're animals with plant symbionts that live within them
Where do coral polyps fit into the trophic pyramid for coral reef ecosystems?
Coral polyps are primary producers in the trophic pyramid for coral reef ecosystems
Why are coral and coral reefs in decline worldwide?
Corals and coral reefs are in decline worldwide due to sediment, excess nutrients, overfishing, and disease.
Why does global warming have a negative impact on coral?
Global warming increases the water temp and causes corals to respond to the stress of these warmer temperatures by expelling the algae that live within them leading to coral bleaching.
Why do coral need to live in the photic zone? How can excess nutrients in water harm coral?
Coral need to live in the photic zone because the algae that live inside of them need sunlight to survive
Excess carbon & excess nutrients leads to smothering of coral which causes them to die
Concepts about The Chesapeake Bay
For bottom waters of Chesapeake Bay, dissolved oxygen is lowest in the summer because thermal stratification is greatest in summer since the prolonged sunlight increases the eutrophication cycle and leads to more hypoxia
In the Chesapeake Bay, oxygen concentrations are lower in bottom waters than in shallow water because stable stratification of the water column prohibits oxygenation of bottom waters
Hypoxia is worse in the upper Bay
What is the role of bacteria in eutrophication?
oxygen levels are lower in bottom water due to the bacteria that consume the sinking organic matter taking up the oxygen and the lack of cycling prohibiting oxygenation
What is hypoxia?
Hypoxia is low concentrations of oxygen in an area that are bad for the marine life inhabiting the water.
caused by: eutrophication, stable stratification of the water column, lack of oxygen in bottom waters, & over sedimentation which kills plants
What is eutrophication?
Eutrophication is when excess nutrients are present in water and cause algae in excess of what can be respired.
Eutrophication leads to hypoxia which is bad for the bay's underwater residents. It also makes the water warmer.
Ex: Crabs can't get enough oxygen, taking out one of the factors of the food chain messes up the whole ecosystem of the Bay
The Susequehanna River is a likely culprit as it is really polluted and considered one of the worst in the country.
What is the cycle of eutrophication & why does "runoff" contribute to eutrophication and related environmental problems?
The cycle of eutrophication is the process that involves the runoff of nitrates and phosphates into a body of water from a polluted source that causes plates and algae to overpopulate which blocks sunlight from reaching the bottom of the lake which leads plants to eventually die and then the bacteria in the lake decompose them and take all the remaining oxygen away from the rest of the life causing the lake or bay or whatever to be devoid of life.
What would help reduce agricultural runoff of nutrients to streams and rivers?
developing wetland or riparian buffers along streams
increase forested area at the expense of croplands
adoption of best practice methods of tilling and fertilizer application
What nutrients cause eutrophication?
Phosphates and Nitrates are the nutrients that cause eutrophication
What role do wetlands play in alleviating the problems that lead to hypoxia?
Wetlands can reduce the nitrogen transport to aquatic environments and can thereby reduce the hypoxia of water
How are deep water waves different than shallow water waves?
Deep water waves' speed is a function of wavelength whereas shallow water waves' speed is a function of water depth
Waves travel faster in deeper water than in shallow water
Shallow water waves interact with the bottom and therefore particle motions near the base of these waves are elliptical rather than circular
deep-water water depth must be > 78 meters
The motion of water particles beneath ocean waves in deep water vanishes at distances below the surface exceeding 1/2 the wavelength
The passage of deep water waves would move you up and down
How does the speed of deep water waves depend on period and wavelength?
Speed = wavelength/period
deep-water wave speed increases with increasing wave period
deep-water waves have a celerity that increases with increasing wave length
What is the depth of wave disturbance for deep water waves?
If you were scuba diving and a wave of wavelength 100 meters passed by, how deep would you need to be to not feel it?
The depth of disturbance for deep water waves is half the wavelength
Therefore, if you were a scuba diver and a wave of wavelength 100 meters passed by, you would have to be at least 50 m deep not to feel the wave.
Why do waves "break" in shallow water? Why are Tsunami considered shallow water waves?
Waves break when the water becomes too shallow for the movement of the wave to be completed to the water at the top of the wave
Tsunamis are shallow-water waves, caused by vertical motion of the seafloor.
They are considered shallow water waves because their speed is dependent upon depth and not wavelength
Deep water wave equations:
S = L / T
S = 1.56 T
L =1.56 T^2
H ≤ L / 7
d deep-water = L/2
d shallow-water = L/20
S = velocity in m/s
T = period in sec
L = wavelength in m
H = Wave height
Why do most places on Earth have two high tides and two low tides each day?
There are two high-tide bulges on Earth, produced by gravity and centrifugal forces, and Earth spins under both of these bulges during a 24 hour 50 minute period
Tides are produced together by gravity & centrifugal forces, caused by inertia & the rotation of the Earth-moon-sun system, producing two bulges
For a given place along the coast (ex: Cape May) are the tides the same each day throughout the year? Do they differ from one week to the next? What's different about them? Why?
The Earth's two tidal bulges are aligned with the positions of the moon and the sun. Over time, the positions of these celestial bodies change relative to the Earth's equator. The changes in their relative positions have a direct effect on daily tidal heights and tidal current intensity
As the moon revolves around the Earth, its angle increases and decreases in relation to the equator. This is known as its declination.
The two tidal bulges track the changes in lunar declination, also increasing or decreasing their angles to the equator.
What are semi-diurnal tides? For semi-diurnal tides, why is one of the highs/lows sometimes higher/lower than the other?
Semidiurnal tidal cycle = experiencing two high and two low tides of approximately equal size every lunar day
Most areas on the eastern coast of North America experience these tidal cycles
Because the moon is on a slightly different schedule than the earth, the tides aren't always the same.
The equilibrium & dynamic theory of tides:
The Equilibrium model = tidal bulges are stationary during a given day. Points on Earth rotate under them, creating 2 high tides and 2 low tides per day
(makes simplifying assumptions, provides a basic understanding of tides)
The dynamic Model = tides created by continental margins & coriolis effect
(complexity of coastlines, bays, ocean basin geometry, earth deformation)
How are spring tides different from neap tides? Sketch the position of the Earth, Moon, and Sun during each case.
Spring Tides = the sun & moon work together when there is a new & full moon
Neap Tides = the sun & moon oppose one another when there is a 1st quarter & 3rd quarter moon
You visit the beach on two days; one during a full moon and one during a quarter moon. Which day is expected to have a larger tidal range? Why?
Full moon because those are spring tides which have high flux because the moon and sun are more in-sync than they are during neap tides
Why does the moon have a bigger affect on tides than the sun?
Because its closer to the Earth
What is an amphidromic point? Why is amphidromic circulation counter-clockwise in the Northern hemisphere?
= the focus for cotidal and corange lines
=tidal crests that move as waves & rotate about the amphidromic point and make one complete cycle every 12 hours and 25 minutes
tide crest enters basin, trends towards right side (N. Hemisphere) due to Coriolis effect; tide crest move in counter-clockwise pattern around the basin of the N. Hemispshere, these rotary waves revolve around a fixed node
For amphidromic tidal circulation, what are co-tidal and co-range lines?
Cotidal lines= connect all points experiencing the same phase of the tide (ex: maximum or minimum), radiating from the central amphidromic point to the antinodes. Because tide waves do not travel with constant speed, but instead respond to changing depth, cotidal lines will not be evenly spaced or consistently shaped.
Corange lines= connect all points with equal tidal range. They form irregular circles which are concentric about the amphidromic point. Tidal range increases with distance from the central point.
For amphidromic circulation in an idealized ocean basin (like the box we studied in class), how long does it take for the wave of high tide to circulate around an ocean?
12 hours 25 minutes
About how many amphidromic systems are there on Earth?
There are 12 on Earth
Why is it valid to think of tides as shallow water waves?
tide wave's length is considerably greater than the depth of the ocean so it behaves as a shallow-water wave
Why do we talk about a sand budget for the beach?
It is a balance between inputs and outputs (transport, river supply, cliff erosion, onshore transport) of a beach creating accretion, erosion, and a steady state
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