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What are the physical stresses of living in the intertidal zone?
air exposure (emersion), temperature and salinity fluctuations, and wave action
What controls the zonation of organisms in the intertidal zone?
A combination of physical and biological stresses. Biological stresses are more important in the lower part of the intertidal zone and physical stresses are more important in the upper part of the intertidal zone
Most all intertidal organisms have planktonic larvae. How do they ensure the larvae will end up in a suitable habitat when they are mature?
They time the release of larvae when physical conditions in the open ocean are suitable for the return of the larvae to shore. If larvae are released during coastal upwelling, they will move offshore, but then be transported back onshore by newly upwelled water when they reach the upwelling front
What is a keystone predator?
A predator whose effect on its community is proportionally greater than it's abundance
What are some adaptations to deal with air exposure (emersion)?
Motile animals can move to wet areas. Sessile animals can close their shells, live in groups to maintain moisture, or be tolerant of water loss (seaweeds)
Under what level of disturbance will we find the most diverse communities? Why?
What is competitive exclusion?
The elimination of one species by another due to competition
What are some adaptations to temperature and salinity fluctuations?
Animals have adapted to be tolerant of these fluctuations and some have developed light coloration to decrease their temperature fluctuations. Motile animals can seek out wet areas where the fluctuations are not as great
What are some adaptations to wave action?
Organisms can be flexible, have strong attachments, and live in groups to decrease the wave force
What are the biological stresses in the intertidal zone?
Predation, competition (food and space), and reproductive success
What are some adaptations organisms have to wave action?
They can live deeply enough in the sediment they are not affected and/or be able to burrow quickly after they are disturbed by a wave
What are some adaptations to low oxygen conditions?
Some animals build a permanent burrow that allows fresh water to flow through. Others have increased oxygen carrying pigments in their blood to be tolerant of low oxygen conditions
What are the general physical characteristics of the sandy beach and mudflat?
Temperature and salinity are fairly constant with depth, but oxygen decreases with depth
What are some examples of subtidal communities?
Kelp forests, sandy beaches and mudflats, and reefs (rocky and coral reefs)
Do sandy beaches and mudflats have high primary production? What do many of the deposit and suspension feeders rely on as a food source?
They have low primary production. Many consumers rely on detritus as a food source
What physical factors are most important for organisms living on the sandy beach and mudflat?
Wave action, particle size, and slope of the beach
What controls the gradient or zonation of organisms on a sandy beach? A mudflat?
The tidal range controls the zonation on the sandy beach and the mudflat is fairly level and has little or no zonation
What is an adaptation to avoid predation?
Have a dial activity pattern. Some organisms are active at the surface only at night at low tide to avoid both aquatic predators and terrestrial predators
What does particle size determine on a beach or mudflat?
How much space there is between the grains and how much the substrate will shift around. The affects how easy it is to burrow in and how much water is retained as well
Where are kelp forests found and how are they ecologically important?
Kelp forests are found in temperate waters with rocky bottoms. They are highly productive and provide important habitat
What controls the amount of oxygen in the sediment?
The amount of oxygen is controlled by the amount of water exchange which is determined by the particle size. The greater the water exchange, the higher the oxygen levels
Why does the temperature in an estuary vary more than the coastal ocean? What part of the estuary has greater temperature fluctuations?
A smaller body of water heats up and cools down more quickly. The upper part of an estuary experiences greater temperature fluctuations
How does salinity change in the water column and the sediments of an estuary with the tidal cycle?
Salinity increases with the high tide in the water column but remains fairly constant in the sediments
Where is oxygen low in an estuary? Why?
Oxygen can be low below the thermocline in a highly stratified estuary because the water below the thermocline does not mix with the oxygen rich surface waters. Oxygen is also low in the sediments because there is a lot of decomposition occurring and the microbes that undergo this process use oxygen. Also, the fine grain sediments do not allow much oxygen exchange
Where is turbidity in a estuary highest? Why? How does it affect organisms living in the estuary?
Turbidity is highest in the upper estuary because sediments are delivered by rivers. Turbidity affects light penetration and so can affect visual predators and primary producers that need light for photosynthesis
What are the important physical (abiotic) factors that organisms who live in estuaries must be adapted to?
Salinity, temperature, turbidity, oxygen
What are the four types of estuaries?
Drowned river valley, bar built, tectonic, fjord
What is an estuary?
A semi-enclosed coastal body of water with a free connection to the sea and in which seawater is diluted by freshwater from the land
What does it mean to be stenohaline versus euryhaline?
An organism that is stenohaline can tolerate a narrow range of salinites while an organism that is euryhaline can tolerate a wide range of salinities
Estuaries are highly productive communities, but primary production is highly variable. What is the other source of food that supports the high secondary production (growth of consumers)?
Estuaries have large amounts of organic matter (detritus). Some is brought in by rivers and some is produced in the estuary
Why do estuaries have low diversity?
Estuaries have high disturbance because of the constantly fluctuating physical environment. Also, estuaries are geologically young and so there has been a short time for species to adapt and become truly estuarine and so there are not large numbers of estuarine species
How are estuarine organisms adapted to changing salinity?
The have reduced permeability to seawater (shells), active membrane pumps that regulate their internal salinity, and they can migrate-move up and down the estuary to stay in the same salinity over a tidal cycle
What is an osmoconformer? An osmoregulator?
What is tidal streaming?
Tidal streaming is a behavior where an organism moves up in the water column on a flood tide and down in the water column on an ebb tide in order to try to maintain position in the estuary
Where is the salt marsh zone in an estuary? What are it's main characteristics?
The saltmarsh is in the upper reaches of the estuary. It is dominated by rooted, flowering grasses in temperate regions and mangroves in tropical regions. The plants trap detritus and this is one of the most productive ecosystems on Earth
What is the ecological importance of estuaries?
They are important nursery grounds for fish and other organisms, they provide flooding control, and they filter pollution from runoff before it reaches the ocean
Where is the mudflat zone? How does the grain size of the sediment affect the productivity?
The mudflats are found in the subtidal and lower intertidal zones. Productivity is inversely related to grain size (smaller grain size, higher productivity)
Where is the seagrass zone found? What is the basis of the food web in this zone?
Seagrasses are found in the intertidal and subtidal areas. The food web is based on detritus as much of the primary production that occurs here in the form of the growth of the grasses is not consumed directly by herbivores
What is a fringing reef? A barrier reef?
A fringing reef is a reef that is directly in the subtidal coastal zone. A barrier reef is a reef that is separated from the mainland by a channel
What is so special about the Flower Garden Banks?
The are the most northerly coral reefs on Earth
What is coral bleaching?
When corals expel their zooxanthellae due to some stressor
How do corals compete with each other for space on the reef?
They can out shade each other and they can exude chemicals to attack neighboring corals
Why is there such high diversity on coral reefs?
Competitive exclusion is avoided because there are so many different niches
What are zooxanthellae?
A specialized dinoflagellate that has adapted to live as a symbiont in corals and some anemones and giant clams
What limits the growth or coral reefs?
Low temperatures, low salinity, low light, and high turbidity which reduces light and can smother the polyps
What is an ecological niche?
The particular space and food resources that an animal utilizes
What is an atoll?
A reef that grows up from the rim of a sunken volcano
Where are coral reefs found?
In tropical, well-lit waters
How is wave energy both beneficial and detrimental to reefs?
Waves bring nutrients and zooplankton to the reef and can be detrimental if the wave energy is too great and it physically damages the corals
How do corals feed?
The polyps capture zooplankton and the corals benefit from the nutrition they get from the symbiotic zooxanthellae
What is a nonrenewable energy resource? A renewable one?
Petroleum is nonrenewable. Wind or tidal energy is renewable
What are two abiotic (non biological) marine resources besides petroleum?
Methan hydrates, sand and gravel, salt, magnesium are four possible answers
What is an example of a non-extractive resource?
Transportation or deposition (depositing waste)
What are the two main types of extractive resources?
Energy and biological resources (food or medicine)
What is the main environmental issue with using large, mid-water trawls for fishing?
They are not selective--they catch any type of organisms that it encounters and so many species that are not the target of the fishery, are killed and discarded as bycatch
What is the largest fishery in terms of amount of fish caught?
What are some of the advantages of aquaculture? Disadvantages?
Aquaculture avoids bycatch and environmental destruction from trawling. The main disadvantage is that the waste can pollute the environment
At what population density do we see the maximal growth rates in a population? Why would this be important to fisheries managers?
Maximal growth rate occurs at an intermediate density. This is the point where a fish population would be giving it's optimal yield for fishing--this would be the ideal condition to try to keep the population in to ensure the fishery is sustainable
The rising concentration of what greenhouse gas is highly correlated with rising global temperatures?
What is the main way that decreasing pH in the oceans will affect organisms?
Decreased pH will lead to increased dissolution of calcium carbonate and other compounds that animals use to build shells and this will limit their growth and could eventually lead to their death and extinction
Why are the oceans becoming more acidic?
The increased amounts of carbon dioxide in the atmosphere are being dissolved in the oceans and are overwhelming the ocean buffering capacity
What is one of the major effects of melting polar ice caps?
Rising sea level
Where do we see the greatest human impacts on the oceans?
In coastal areas
Excluding major oil spills like the Deepwater Horizon event, what is the source of most of the oil in the ocean?
Where are most of the plastics in the ocean concentrated?
In the ocean gyres
What is the main source of pollution in the ocean?
Runoff from the land
Briefly describe the concept of biomagnification using the example of DDT
Biomagnification is the process by which a pollutant becomes more concentrated in an organisms with each increasing trophic level. In the case of DDT, this chemical was passed up the food web to birds where the concentrations were high enough to result in thin egg shells making them nonviable and having huge impacts on bird populations
How does rising ocean temperature affect corals?
Higher temperatures cause stress and leads to coral bleaching
What is the major effect of rising ocean temperatures at the poles?
Decreased ice cover
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