Cumulative Multiple Choice
Match the depth zones with their corresponding depth ranges. epipelagic abyssopelagic mesopelagic bathypelagic
< 200, 4000 - 6000, 200 - 1000, 1000 - 4000
A=32, B=25, C=15, and D=11 represent different potential species richnesses of an ecosystem. In species-rich systems, ecosystem functionality is unlikely to be adversely affected by the loss of one or two species. The difference in species richness between A and D is 32-11=21. This means that the ecosystem A would have to lose 21 species for it to have the richness of ecosystem D. Is the difference in species richness greater between A and B or C and D? Is the loss in ecosystem function greater when it shifts from A to B or from C to D? A. A and B; C to D B. C and D; A to B C. C and D; C to D D. A and B; A to B
A
Competition is no more intense (i.e. the frequency with which it occurred) but was more severe (implied) away from the poles. Which factors affect the trends in the outcomes of competition across latitudes? A. biological interactions at lower latitudes B. disturbances at high latitudes C. taxa size D. relatedness of species
A
Estuarine organisms can demonstrate three responses to increases in flow, and subsequent large decreases in salinity, particularly in the upper estuary where seasonal inputs can lower the salinity to practically fresh water: either the organisms tolerate the changes, they migrate or drift to avoid low salinity water, or they do not survive at all. In the first scenario, temporal samples of the community in an estuary would demonstrate few changes, whereas the latter two responses would result in the removal of the organism from the assemblage and possible shifts in community up and down the estuary. What is the primary driver of the changes in flow in estuaries? A. seasonal precipitation B. glacier melt C. increasing tides D. boat traffic
A
The figure depicts two simple food-chains that assume that all production is used by the next trophic level. Energy is lost in every step of the food chain because transfer efficiency is less than 100 percent. Which baleen whale has higher production and why? A. the whale that feeds on zooplankton because of fewer transfers of energy up the food chain B. the whale that feeds on zooplankton because of more transfers of energy up the food chain C. the whale that feeds on fish because of fewer transfers of energy up the food chain D. the whale that feeds on fish because of more transfers of energy up the food chain
A
The seasonal cycle of the trophic metabolism in temperate waters may be considered in three stages: Spring, Summer, and Autumn/Winter. Which of the following describes the Autumn/Winter stage? A. heterotrophy-dominated period B. period of regenerated phytoplankton production C. main period of new phytoplankton production
A
The trend in individual organism size shows a less consistent pattern and varies between different sized organisms. At a global scale for both the macro and meio benthos there is a decrease in mean body size with depth that has been related to decreasing food concentration. However, at regional scales trends differ and different taxonomic groups also respond differently. For nematodes and gastropods there is an overall reduction in body size with depth, however amphipods, isopods, ostracods, pycnogonids and anemones show an increase. Some larger organisms also show increase in size with depth. Figure c, plots individual fish body size against depth: fish on average get bigger as you move into the deep sea. Depth-related increase in size becomes extreme in some deep-sea groups, which demonstrate gigantism: giant organisms are one of the major features of the deep sea, a trend also apparent in polar seas. Given that information, what is a reasonable hypothesis for gigantism? A. Gigantism is a function of cold temperatures. B. Gigantism is a function of extreme depths. C. If gigantism is a function of depth, then temperature plays a role. D. Is gigantism a function of temperature or depth? E. Gigantism is a function of allochthonous systems.
A
When the larvae of the clams settle in 1968, the larvae are abundant and small. Over the period of several years, the individual clams increase in mass, while at the same time many individual clams die, until after about 8 years the last remaining large clam dies (figure a). The total biomass of this population at any time can be calculated by multiplying the abundance by the average weight of the clams. The total biomass of clams increases from near zero in 1968 to a maximum in 1971, and then decreases again to near zero in 1975. Biomass is therefore added to the cohort by the growth of individual organisms, while biomass is lost from the cohort due to mortality of individuals. Mortality occurs due to predation, disease, senescence or changing environmental conditions such as hypoxia. What could cause a species with an equivalent growth to reach a higher population biomass maximum (figure b) and therefore have a higher production? A. lower mortality rate B. lower growth rate C. higher mortality rate D. increases in predation
A
Which is the best explanation of photosynthesis. Consider why higher trophic levels rely on it. A. Photosynthesis is the process by which plants take in energy from the sun, and water and carbon dioxide from the environment. Plants use chloroplasts to produce sugar. They also release oxygen into the environment. B. Photosynthesis is the process by which plants take in sunlight, oxygen, and water to turn into sugar. The plant will use the sugar to fuel cell processes. C. Photosynthesis releases carbon dioxide into the environment and produces sugar for the plant by taking in energy from sunlight, the air, and water and using various chemical processes to convert this energy. D. Photosynthesis is the process by which plants absorb energy from sunlight, carbon dioxide from the air, and water from the ground. Plants use chloroplasts and various processes to turn this energy into oxygen.
A
Life can be difficult at times and we can all use some grace. How do I afford you grace without requiring documentation or explanation? Choose multiple correct answers. A. I drop the lowest Quiz and Perusall Article Discussion grades for everyone. B. Late assignments are accepted with a minor 10% deduction per day. C. No grace from me, I'm too cold-hearted!
A & B
Why do we care to quantify secondary production in the marine environment? A. To understand the energy flow in food webs B. To estimate the carrying capacity of ecosystems C. To identify the species most valuable for human consumption
A & B
Which of the following statements are true? A. Nutrient mineralization is extremely important as without efficient recycling of nutrients, the food webs in the oceans, as in any other ecosystem, would rapidly stagnate. B. Food chain efficiency is near 100% from one trophic level to the next. C. Th food web inefficiency is a consequence of the very large fraction of organic material that is respired and recycled back (remineralized) to form the inorganic carbon.
A & C
Ecologists and the fishery biologists are most interested in somatic production (compared to gonad production) because this represents the quantity of matter and energy that is available as food for the organisms in the next trophic level, such as natural predators, and for human consumption in the case of commercially exploited species. What scenarios make it difficult to calculate secondary production accurately? A. regeneration of arms lost by starfishes B. crabs autotomizing limbs C. regeneration of siphons that are cropped by fish and shrimp predators D. generation of offspring after a mating event
A, B & C
How does habitat fragmentation in seagrass meadows affect the community? A. discrete patches of seagrass can form islands that are separated from the next patch by bare sediment, potentially isolating organisms from the main population B. increases the edge effect within seagrass habitat C. change water flow and sediment deposition, and ultimately physical conditions within a bed
A, B & C
One might then expect that good powers of osmoregulation would be a distinctive feature of all successful estuarine organisms. In fact, they exhibit a very wide range of abilities to osmoregulate. Many organisms, such as molluscs, have little, if any, osmoregulatory ability and are thus termed osmoconformers. They survive and thrive in estuaries by exhibiting exceptionally high tolerance to diluted blood concentrations, which is sufficient over most of their range in estuaries. At the other extreme, crustaceans are amongst the most efficient osmoregulators. Species such as the mysid Praunus flexuosus are able to maintain a relatively constant internal medium across a very wide range of external salinities. Many other animals fall between these two extremes in their osmoregulatory ability. Some algae can also survive extreme salinity variation; the green alga Ulva is perhaps the most tolerant, changing ionic and metabolic concentrations in response to variations in salinity. Estuarine Ulva also possess thinner and stretchier cell walls than fully marine species, allowing changes in tissue water content and cell volume. If organisms have found ways to deal with variable salinity conditions in an estuary, what are some of the other factors drive their realized distributions? A. benthic sediment B. temperature C. water flow
A, B & C
Seamounts are large geomorphological features of the deep sea. The definition of a seamount originally only referred to structures that were over 1000m in height (Menard, 1964), with smaller structures referred to as knolls (500-1000m in height), and hills (100-500m in height). However, the term 'seamount' is applied by some to all structures over 100m in height. Estimates of the number of seamounts globally vary from 200,000 to 25 million depending on the definition used. However, the most recent estimates based on the highest resolution data suggest there are between 10,234 and 33,452 seamounts, and 138,412 knolls and hills. Seamounts, knolls and hills cover approximately 21 percent of the ocean floor; therefore, they represent a significant habitat within the deep-sea ecosystem. They have a major influence on physical oceanography, which in-turn influences the communities found on and around seamounts. How so? A. trapping of the dial vertical migrators over the seamount summit as they descend to depth B. localized upwelling of nutrients increasing primary production C. accelerated horizontal currents which bring food more rapidly to the seamount community
A, B & C
The taxonomy and origin of seagrasses has been subject to much debate, but seagrasses are clearly polyphyletic and generally assigned to two families, Potamogetonaceae and Hydrocharitaceae, neither of which is related to the grasses familiar on land. Fossil evidence suggests that seagrasses first appeared in the marine environment around 100 million years ago, the oldest Cretaceous fossils include the genus Posidonia, but their ancestors are uncertain. Two candidates have been put forward: coastal plants (e.g. saltmarshes, mangroves) and freshwater hydrophytes. Some seagrasses have lignified stems and two genera are viviparous, linking them to mangroves, while freshwater plants show many of the adaptations required to survive in the marine environment, such as basal meristems and lacunar gas transport systems. Certainly, it seems likely that the seagrass habitat has evolved several times over the last 100 million years (perhaps from both ancestral routes), with the genera Phyllospadix and Enhalus appearing significantly later than other seagrass groups. However they have evolved, seagrasses possess three key attributes that enable them, uniquely, to colonize the marine environment, including which of the following? A. hydrophilous, and thus submarine, pollination B. leaves with sheaves adapted to high-energy environments C. extensive lacunar systems that enable transport of oxygen to the below-ground structures in anoxic sediments D. a C6 photosynthetic pathway that enables carbon fixation in saline water
A, B & C
The ultimate growth of an organism is a result of the balance between the energy input and the necessary energetic costs for cell processes to take place and of course reproduction to maintain the following generation. The energetic gains, investments, and losses of individual organisms include: A. Material investments in skeletal formation, production of energy storage compounds, and formation of reproductive material B. Material and energy gains from photosynthesis or chemosynthesis C. Energy and material losses from movement, buoyancy, excretion, osmoregulation, nutrient uptake, and respiration D. Material losses from prey consumption and primary production.
A, B & C
Why are pelagic fisheries sometimes considered among the most straightforward to manage? A. the risk of bycatch is minimized B. pelagic fish form large single-species shoals C. the target species are impossible to over-exploit D. the gear does not damage the benthic habitat
A, B & D
Seagrass beds provide a range of goods and services of benefit to coastal ecosystems and humans. To put an economic value on the world's ecosystems relating to these services, seagrass/algae beds are worth $19 004 ha-1 y-1. What ecosystem services do seagrasses provide? A. carbon sequestration B. a nursery ground for fishery species C. a habitat maintaining high levels of biodiversity D. stabilizing features within the coastal landscape, a natural form of coastal protection E. enhance sediment stabilization and thus prevents erosion F. food for large endangered grazers (e.g., green turtles) G. slow water currents through their baffling effect, encouraging sediment to settle and preventing resuspension H. water purification and nutrient cycling
A, B, C, D, E, F, G & H
What factors affect the physical processes affecting the continental shelf environment? A. relatively shallow depth B. seabed topography C. swimming speed of local megafauna D. proximity to land E. inputs from freshwater sources
A, B, D & E
What are some of the major differences between the arctic and antarctic? A. The largely land-locked Arctic Ocean has considerably more ice, which lasts several years compared to the larger Southern Ocean, which has predominantly ice that lasts just one year. B. The Arctic is largely cut off from terrestrial influence, except for limited aerial deposition, whereas the Antarctic basin is characterized by a high input of fresh water from many large river systems. C. Surface melt ponds are a conspicuous feature of the surface of Arctic ice in summer. These are only rarely found in Antarctic ice. D. There are no river inputs into the Southern Ocean, in stark contrast to the Arctic basin into which flows considerable freshwater run-off from large river systems.
A, C & D
What factors enhance the phenomenon of 'gigantism' in the polar regions? A. high dissolved oxygen concentrations B. high rates of mixing C. longevity in polar waters D. low temperatures
A, C & D
Many fish and invertebrates graze on seagrasses, but what are the most impactful grazers in seagrass meadows? A. Sirenia (dugongs and manatees) B. crabs C. sea urchins D. parrotfish E. green turtles
A, C & E
What are the three greatest threats to coral reefs, which are thought to exacerbate disease, storms and COTS? A. water quality B. ecotourism C. boating D. climate change E. fishing
A, C & E
What are the primary abiotic factors that affect the ecology of estuaries? A. dissolved oxygen B. bacterial processes C. temperature D. sediment E. species richness F. salinity
A, C, D & F
An estuary is an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, usually divisible into sectors that include: A. middle, subject to strong salt and freshwater mixing B. supra, subject to glaciation and retention of fresh water C. sub, disconnected from the fresh water source D. upper, characterized by fresh water but subject to daily tidal action E. lower, free connection with the open sea
A, D & E
Body size has a key role in the function, ecology, physiology, and evolution of individual organisms. Contrasts in animal size surround us, many are simply between organism types: all nematode worms are, for example, smaller than brachiopods, which are all smaller than marine reptiles. For nearly all animals, an increase in volume will change their surface area to volume ratio. This is crucial to functions such as gas exchange and feeding. There have been many explanations for why animals should increase in size (such as reduction of predation or increasing feeding efficiency). What strategy have some organisms effectively employed to escape surface area to volume constraints on respiratory or feeding surfaces (i.e., they stayed small or got smaller over time)? A. gigantism B. coloniality C. camouflage D. increased complexity
B
Many seagrasses show a tolerance to a wide salinity range (for example, Z. marina occurs in full-strength seawater and also down to a salinity of 5 in the Baltic), and seagrasses often are a major feature of estuaries and hypersaline lagoons, although the majority of species perform optimally under fully marine conditions. However, success in estuaries and similar coastal systems may be limited by high levels of plant nutrients in the water, which is becoming an increasing problem through agricultural run-off. Such high levels of, for example, nitrate and ammonium, can directly affect the growth of seagrass, but it also influences the competitive balance between the seagrass productivity and that of algae associated with the seagrass meadow, represented by an epiphytic assemblage growing on the leaves or by macroalgae that grow alongside, or amongst, the seagrass meadow. In the figure above, squares represent macroalgae and circles represent seagrass, what happens to the competitive dynamic between seagrass and macroalgae at high levels of nitrogen loading? A. seagrass and macroalgae reach a balanced equilibrium B. macroalgae outcompetes seagrass C. seagrass outcompetes macroalgae
B
Researchers studying seagrass ecosystem dynamics, often collect samples of the seagrass to test for concentrations of carbon, nitrogen, phosphorus, and sometimes sulphur. Why do we care to test for those atoms? A. Algae depends on them as nutrients but seagrasses do not. If we see them in seagrasses, we know they are diseased. B. They are major inorganic nutrients needed for the many molecules that make up a living organism at any trophic level. C. They are required only for photosynthesis. D. Only carbon and nitrogen are found nearshore, the others must come from upwelling.
B
Zooplankton blooms are only able to develop once phytoplankton biomass and production has become sufficient to sustain zooplankton grazing rates. In many temperate waters, therefore, peaks in zooplankton biomass occur in spring and autumn slightly after the phytoplankton blooms. In high latitudes, where seasonality is extreme and the phytoplankton bloom is limited to a single spring/summer peak, some zooplankton species survive the dark, food impoverished winter months in deep water in a dormant state called diapause. In late winter or early spring copepods emerge from diapause and migrate to the surface to spawn. Because of the short production season (phytoplankton blooms are short-lived), the timing of reproduction is critical at high latitudes. What do zooplankton in the high latitudes do to ensure they reproduce in time for their young to be in place to fully exploit the short-livid phytoplankton bloom? A. They produce a large number of offspring throughout the production season in hopes that at least some of them will be in place to fully exploit the short-livid phytoplankton bloom. B. They use stores of lipids from the previous season to fuel reproduction so they can spawn early, independent of the present year's phytoplankton bloom. C. They only reproduce when the present year's phytoplankton bloom is sufficient to support their young. D. The feed throughout the phytoplankton bloom and reproduce at the end of the production season.
B
Trophic cascades are likely to occur when the linkages between species are _________ and ________. A. weak B. strong C. occur between species assigned to minor trophic levels D. occur between species assigned to major trophic levels
B & D
What are the main growth-limiting nutrients in marine systems? A. sulphur B. phosphorus C. carbon D. hydrogen E. nitrogen
B & E
What physical factors differ between neritic and oceanic zones? A. oceanic zones have heavier particulate loads B. neritic zones have higher nutrient loads C. distance from shore D. neritic zones have heavier particulate loads E. oceanic zones have higher nutrient loads
B, C & D
When considering primary production on a global scale, the advent of satellite color images of chlorophyll distribution around the globe have been very successful in showing us that primary production is far from uniform at a large scale. Indeed, large-scale patterns in primary production are partly used to define distinct regions or biomes of the world's seas. Ultimately what are the major factors that govern primary production in marine systems: A. Elements—carbon, nitrogen, and phosphorus are limited in most marine systems. B. Nutrients—that can be exhausted in upper water layers, but are generally available in the deeper part of the water column. C. Light—only available in the upper part of the water column (max 200 m). D. Stability—to allow algal growth in surface water layers. E. Mixing—to replenish used nutrients from lower water layers to surface.
B, C, D & E
What are the benefits to corals from their symbiotic relationship with algae (zooxanthellae)? A. Protection from UV damage by animal tissues B. Conservation of nutrients C. Increased growth and reproduction D. Increased calcification rate E. Maintenance of a high population density of a single genotype by host under uniform environmental conditions F. Supply of reduced carbon providing low respiration costs and conservation of metabolic resources G. Sequestration of toxic compounds by algae H. Supply of CO2 and nutrients from host maintenance in photic zone
B, C, D, F, G
What are some of the psychrophilic organisms that make up the communities found in sea ice? A. baleen whales B. foraminiferans C. krill D. diatoms E. bacteria
B, D & E
Handling prey in the pelagic environment is more energetically costly than it is in terrestrial or benthic environments. How do most pelagic organisms minimize handling time? Hint: this also shapes pelagic food web structure. A. they only consume large organisms that provide the most calories B. they use cooperative hunting tactics C. they consume their prey whole
C
Illustration of the occurrence and phylogenetic relationships of the major marine planktonic prokaryote clades. The illustration is based on metagenome-assembled genomes from the Tara Oceans expedition data. Which two display the greatest evolutionary distance? A. Chloroflexi and Actinobacteria (left of figure) B. Nitrospinae and Deltaproteobacteria (bottom right of figure) C. Heimdilarchaeota and Woesebacteria (top of figure) D. Cyanobacteria and Bacteroidetes (bottom left of figure)
C
The biological pump is a collective property of phytoplankton-based food webs. Together with the solubility pump (right), which is driven by chemical and biological processes, it maintains a sharp gradient of CO2 between the atmosphere and deep oceans, where carbon is stored. Third pump leading to long-term carbon storage is the Microbial carbon pump (MCP), where carbon is stored into biomolecules that are very resilient to biological degradation and can persist thousands of years in the ocean. Most of the phytoplankton POM production is decomposed into CO2 in the upper water layers, from where it re-enters the atmosphere. Part of the produced POM is exported into deeper water layers, decomposed into CO2 and stays dissolved in deep water. The food web structure, relative abundance of species, and production control influence how much CO2 will be pumped into the deep ocean. Microbial carbon pump functions throughout the water column but degradation of recalcitrant DOC is faster in upper ocean due to higher UV irradiation. The net result is transport of CO2 from the _____________. A. deep ocean to the atmosphere B. small phytoplankton to zooplankton C. atmosphere to the deep ocean D. bacteria to the microzooplankton
C
The figure shows the impact that microbial organisms can have on flow over the seabed by infilling the gaps between sediment particles to create a 'smoother' surface. A rough bed will experience greater stress for the same overall flow than a smooth bed. This has important consequences for plants and animals living at the sediment surface. Under rough, turbulent conditions, turbulent eddies are formed that impact the bed and increase the likelihood of erosion of the sediment and resident biota. Under such conditions it is not possible for the viscous laminar sub-layer to form. This is sometimes termed the boundary layer, which acts as a hydrodynamic and molecular buffer zone between the bed and the flow above. When this layer is present it significantly affects the flow of particles and nutrients to and from the bed. The biological significance of the physics becomes clearer when we consider the consequence of animal growth on the seabed. Mussels settling onto a smooth substratum will increase the surface complexity of the bed making it 'rougher'. This in turn will increase turbulent flow over the seabed. Why is turbulent flow beneficial to filter feeders such as mussels and oysters? A. The turbulent flow prevents microbial organisms from reaching the vulnerable filter feeding organisms. B. The turbulent flow pushes the filter feeders higher into the water column where their food is abundant. C. The turbulent flow breaks down the boundary layer and encourages a downward transport of plankton (food and larvae) from the layers of water above. D. The turbulent flow is not benefitial, but the filter feeders have learned to adapt by producing strong currents through their siphons.
C
The marine snow particle colonized by bacteria, which turns particulate organic matter into DOM. Plume of excess DOM trailing behind the particle as it sinks contains carbon (C) and mineral nutrients (N, Fe, Si). Free-living bacteria (red) are attracted to the plume by their chemokinetic ability and grow rapidly. Particle colonizers may also release their progeny (blue) into the plume. High concentrations of bacteria attract protozoa, which attract larger animals (metazoa). Marine snow particles and their plumes may thus become focal points for the upper ocean microbial food webs. Which of the following statements is NOT true? A. The fate of marine snow and the rate at which it is decomposed by its bacterial hitchhikers are critical to the behaviour of the oceans as a potential sink for carbon. B. It is thought that these flakes are the main vehicle for the transport of organic matter from the upper ocean to the ocean floor and, as such, a vital step in the carbon cycle of the oceans. C. The marine POM can also be generated by physical forces that convert DOM into particles that have the identical chemical structure of snowflakes. D. Marine snow particles are a habitat for marine micro-organisms and oases in an otherwise nutritional desert.
C
The three-dimensional extent of the seabed habitat, including the organisms that live on and within it, depends on the _____________. A. soft bodied animals like anemones and sea pens B. water circulated into burrow systems C. the hardness and stability of the seabed D. adaptations such as a flattened body form
C
What determines the maximum depth at which most corals are found? A. nutrient availability B. temperature C. light availability D. substrate
C
What other important processes are driven by the ocean circulation? A. transport of oxygen from the depths to the surface B. transport of carbon dioxide for sea surface gas exchange C. transport of dissolved organic matter and inorganic nutrients D. transporting oxygen to the ocean depths
C & D
Halophila stipulacea, a seagrass native to the western Indian Ocean, the Persian Gulf and the Red Sea, has successfully spread to the Mediterranean and southern Caribbean. Possibly transported by pleasure yachts, it was only the second seagrass species known to have transoceanic establishment (Ruiz & Ballantine 2004). The invasive H. stipulacea is fastgrowing, produces a large number of seeds, can rapidly spread vegetatively, and can tolerate a widerange of salinities, temperatures, light levels, and disturbance regimes (Short et al. 2010). These factors have contributed to its rapid expansion in the Caribbean since its initial sighting in Grenada in 2002 (Ruiz & Ballantine 2004). As of 2017, it had been documented throughout the Lesser Antilles and as far north as Puerto Rico (Ruiz et al. 2017). In its native range, H. stipulacea is readily consumed by dugongs (Short et al. 2010), but H. stipulacea could be released from this 'enemy' pressure in the Caribbean ifnative large-bodied grazers do not recognize it as a potential food source or preferentially consume native seagrasses competing for space. To date, H. stipulacea in the Caribbean has only been reported in seagrass habitats used by green turtles, and it is unknown how manatees Trichetus manutus, another large-bodied Caribbean grazer, will react when the invasion reaches their habitat. Why do we classify H. stipulacea as an invasive species? A. the Invasive Species Specialist Group labeled it as invasive B. it may or may not be consumed by local grazers C. it is non-native to the ecosystem under consideration D. its introduction causes or is likely to cause economic or environmental harm or harm to human health
C, D
Which organisms are responsible, at least in part, for the secondary production in the oceans? A. zooplankton B. fish C. phytoplankton D. sea turtles E. algae
C, D & E
Sessile particle feeders modify their feeding activity in relation to flow velocity by ________ feeding when the delivery rate of particles is too low or when current velocity might incur physical damage as a result of shear. A. continuing B. decreasing C. increasing D. stopping
D
The figure depicts the (a) relationship between estuary size and the average number of five wader species present. (b) Rrelationship between prey density (Hediste, Scrobicularia) and wader density (curlew, Numenius arquata). If the birds are distributed based on prey availability alone, they are adhearing to which theory? A. interference and depletion effect B. ideal despotic distribution C. Allee effect D. ideal free distribution
D
The small size and large surface-to-volume ratio of micro-organisms endows them with extraordinarily __________. A. low metabolic rates B. broad habitat ranges C. narrow habitat ranges D. high metabolic rates
D
What role do parrotfish, such as these excavating Captain Parrotfish (Chlorurus enneacanthus) play on coral reefs? A. They provide cleaning services to other fish by removing ectoparasites. B. They break down the reef so that it does not get too tall and reach the surface of the water. C. They are apex predators controlling the grazer populations. D. They scrape away the algae and some of the underlying dead reef structure, providing ideal conditions for coral settlement and growth. E. They control coral populations by consuming the gametes expelled during spawning.
D
ntensity of zonation in relation to latitude and the position of the Polar Frontal Zone (PFZ). Diagram is a schematic suggesting manner of change of intensity of zonation based on strength of littoral macrobiota patterns at sites at latitudes indicated. Given the pattern of zonation across latitudes, where would you expect to see the highest predation pressure and competition for space? A. Relatively high latitudes B. The Polar Frontal Zone C. Predation pressure and competition are constant across latitudes D. Relatively low latitudes
D
While corals are laying down limestone and building reefs, many other reef processes are eroding the limestone and producing coral rubble and coral sand, even on undisturbed reefs. Erosion can be due to physical processes and biological agents, such as parrotfishes, urchins and boring sponges and algae. For example, parrotfishes scraping and excavating live and dead corals produce around 85 percent of the sand on some Maldivian reef flats, directly contributing to island growth and maintenance. Reefs are presumed to be 'healthy' and showing net growth when corals have the upper hand. Corals, and some other organisms such as calcifying algae, actively lay down new calcium carbonate and grow reefs outward and upward. However, if erosion is the dominant process the reef fails to grow. Even on growing reefs, erosion rates are usually high and net accretion only just exceeds net loss. Relatively small shifts in the structure of reef communities can shift the balance from net accretion to erosion. Recent work has indicated that when coral cover drops below 10 percent (though this number varies among locations), reefs tend to enter a net erosional state, whereas above this percentage cover of corals, accretion is more likely. Increasingly, the ecological condition of coral reefs is too poor for reef growth to keep pace with projections of sea-level rise. Reef growth is a balance between ________ and _________. A. acidification B. bioaccumulation C. deposition D. accretion E. bioerosion
D, E
What is the single most limiting factor for humans in the deep sea (i.e., why can't we go there)? A. Sediment B. Temperature C. Dissolved Oxygen D. Light E. Bottom Currents F. Hydrostatic Pressure
F
Marine prokaryotes are central for marine ecosystem functioning. A large fraction of the organic matter that is synthesized by primary producers is released as DOM in water and taken up almost exclusively by [ Select ] ["fish", "zooplankton", "bacteria", "phytoplankton"] . Most of the DOM is respired to [ Select ] ["POM", "DMS (dimethylsulphide)", "carbon dioxide"] while a fraction is assimilated and re-introduced into the classical food chain through the microbial loop from low to high trophic levels (phytoplankton to zooplankton to fish). Detrital carbon in the form of [ Select ] ["DMS (dimethylsulphide)", "POM", "DOM"] can also be turned into DOM or transported down into the benthos. The action of bacteria on organic matter plays a major part in carbon cycling through DOM. The microbial loop therefore influences the air-sea exchange of carbon dioxide, carbon storage through sinking and carbon flux to fisheries.
bacteria, carbon dioxide, POM, carbon
Secondary production is high in ecosystems with a [ Select ] ["high", "average", "low"] primary production, and higher for organisms that feed at [ Select ] ["high", "average", "low"] trophic levels.
high, low
The global distribution of kelps is physiologically limited by light at [ Select ] ["mid", "high", "low"] latitudes and by nutrients, warm water, and competition from macrophytes at [ Select ] ["mid", "high", "low"] latitudes Urchins Strongylocentrotus droebachiensis are major herbivores of kelp. Over-fishing and the subsequent extirpation of cod from the inshore waters of Nova Scotia released sea urchins from top-down control by predators leading to a sequence of phase shifts between sea urchin and kelp dominated communities. Only the intervention of sea urchin disease increased natural mortality sufficiently to permit the periodic re-establishment of the kelp in this system.
high, low, top-down control by predators
Hydrothermal vents are exceptional among deep-sea islands, and vastly different from the rest of the deep sea, in having a huge biomass of associated organisms. Clearly, alternative methods of food supply are sustaining these communities, and this production is autochthonous and related to the supply of reduced compounds (particularly sulphur compounds) emerging from the vent. Vent assemblages are sustained by primary production generated by [ Select ] ["algae", "bacteria", "photoautotrophs"] through chemosynthesis and considered of little importance until recently, when vents were investigated. The other major group present on vents are decapod [ Select ] ["seaweeds", "crustaceans", "clams"] , which scavenge off other vent animals. Squat lobsters are common, but Pacific vents also have associated crab species (e.g. Bythograea thermydron) that are key members of the vent food-web but comparatively uncommon anywhere else in the deep sea due, perhaps, to the planktonic larval strategy generally adopted by the group. How this species has colonized and adapted to life on vents is therefore an interesting question, but it would appear that larval stages of the crab remain in the vicinity of the vent. Like shallow-water crabs, large numbers of eggs are produced, but first-stage zoea of Bythograea have been captured in plankton tows of bottom water over vents rather than at the surface thousands of metres above. However, the most remarkable feature is the megalopa (settling larval stage), which is enormous compared with shallow-water crabs (5-10 cm carapace length) and common in both water overlying vents and within clumps of Riftia where they appear to take refuge.
bacteria, chemosynthesis, crustaceans
Carbon has two stable isotopes, 12C and 13C. Due to different modes of photosynthesis, plants accumulate the heavy isotope of carbon at different rates (see Chapter 2). Therefore, it is possible to distinguish between, for example, a leaf from a tree and a green alga by determining the stable isotope ratios within each plant's tissues. Analysis measures the proportion of the heavy isotope and compares this with the standard. The difference is expressed as δ13C (‰), which varies depending on the source carbon. Therefore, an isotopic signal can also be obtained from detritus, which indicates its origin. The resolution is improved considerably by also determining the stable isotope ratios of nitrogen, or preferably sulphur, within the material, giving a second axis allowing separation of carbon sources that overlap when carbon alone is used. The isotopic ratios of C and S are relatively conserved when plant material is ingested and incorporated into the bodies of animals, so analysing the tissues of estuarine animals will enable information to be obtained on the carbon source used by these organisms. This has proved a very important tool in aiding our understanding of how estuaries function. Analysis of nitrogen isotope ratios can provide further evidence helping to determine the position of organisms within food webs. The heavy isotope of nitrogen (15N) concentrates up the food chain at approximately 3‰ per step. Therefore, carbon isotopes are used to determine the [ Select ] ["base of the food web", "age of the organism", "trophic level of the organism", "species"] and nitrogen isotopes can help us determine the [ Select ] ["base of the food web", "age of the organism", "species", "trophic level of the organism"] .
base of the food web, trophic level of the organism
(X) variables such as sediment, dissolved oxygen, currents, temperature, and light do not vary greatly in the deep sea and therefore do not have as dramatic a controlling influence in the deep sea as in other marine systems such as estuaries and rocky shores. To discover what may be the major limiting factor for abyssal organisms we have to look at (X) variables.
environmental, biological
Examples of three distinct types of estuary based on method of formation. (a) Chesapeake Bay, USA, a coastal plain estuary resulted from (X) , (b) San Francisco Bay, USA, a tectonic estuary resulted from (X)isostatic variation , and (c) Great South Bay, Long Island, USA, resulted from (X).
eustatic sea-level rise, isostatic variation, offshore deposits, forming barriers across bays and inlets (bar-built)
The relationship between primary production and nekton production. Fish and squid production = (0.095 × Phytoplankton production) - 3.73, r2 = 0.96. 1 = Atlantic Ocean gyre centre, 2 = Atlantic ocean gyre boundaries, 3 = Hawaiian waters, 4 = Bothnian Sea, 5 = Gulf of Riga, 6 = Gulf of Finland, 7 = Baltic Sea, 8 = Nova Scotian shelf, 9 = Gulf of Maine, 10 = Mid-Atlantic bight. R-Squared is a statistical measure of fit that indicates how much variation of a dependent variable is explained by the independent variable(s) in a regression model. Regions of the world's ocean with [ Select ] ["high", "moderate", "low"] primary productivity support [ Select ] ["poorer", "richer"] pelagic communities, with lower total biomass, than do regions with low primary production. The relationship between primary production and nekton production is [ Select ] ["negative", "positive"] and [ Select ] ["strong", "weak"] .
high, poorer, lower, positive, strong
As depth increases, pressure [ Select ] ["remains constant", "decreases", "increases"] , UV radiation [ Select ] ["remains constant", "increases", "decreases"] , oxygen (to about 100 m) [ Select ] ["remains constant", "increases", "decreases"] , and total mass of biota per unit volume of seawater [ Select ] ["increases", "decreases", "remains constant"] .
increases, decreases, decreases, decreases
The schematic shows the major pool of carbon within the oceans. Particulate organic carbon (POC) includes all organisms from bacteria-sized particles to whales. Dissolved organic carbon (DOC) is generally considered to be all carbon that can pass through a 0.2 μm filter. Chemolithotrophs are autotrophic prokaryotic microbes deriving their energy for growth from [ Select ] ["decomposition and respiration of organic material", "inorganic reduced compounds"] and organotrophs are heterotrophic prokaryotic microbes deriving their energy and carbon from [ Select ] ["decomposition and respiration of organic material", "inorganic reduced compounds"] .
inorganic reduced compounds, decomposition and respiration of organic material
The future of rocky and sandy shores depends on the temporal perspective taken. The expansion of human populations along coastlines is likely to increase (X) and potentially shading from industrial structures (e.g. around port developments, or from high-rise blocks of apartments). For example, reproduction in many organisms is closely aligned to changing seasonal patterns in day-night illumination. Species of conservation concern such as turtles may be confused by excessive night-time illumination along beaches leading to reproductive failure. Beaches are dynamic physical entities, maintained by processes operating above and below the beach as commonly defined (Brown & McLachlan 1990 Links to an external site.), so that changes in sediment supply and wave climate are likely to impact greatly on beach dynamics. For sandy shores, (X) may increase erosion, create a steeper beach profile and increase turbidity. With less organic matter retained in the beach, there will be a lower biomass of infauna. These problems will be exacerbated if beaches are protected by hard engineering, as the available beach area will be progressively sandwiched between a rising sea-level and an immovable structure, the so-called (X). The net result of sea-level rise for many soft shores will therefore be a smaller, less productive beach, although other scenarios are possible, depending on sedimentation patterns and the relative rise of the sea and land.
light pollution, accelerated sea-level rise, coastal squeeze
Seabed habitats can be categorized according to the characteristics of the substratum (hard or soft-sediment). The physical characteristics of soft-sediment habitats are indicative of the physical energy that affects the seabed, with mud occurring in (X) energy environments, while coarse sands occur in tidally swept areas exposed to (X) . Some habitats are composed of living biota such as kelp forests, maerl beds, and oyster reefs that are critical links with their associated communities of organisms.
low, wave action
The figure shows the annual primary production as g carbon m-2 year-1 of the oceans from a global perspective. The high primary productivity near the coastal regions, defined in the figure as [ Select ] ["more than 500 g of carbon per square meter per year", "more than 100 square meters of carbon per year", "less than 100 g of carbon per square meter per year", "more than 500 square meters of carbon per year"] , is driven by [ Select ] ["low light conditions", "high temperatures", "upwelling of nutrients"] .
more than 500 g of carbon per square meter per year, upwelling of nutrients
Seagrass meadows make available a high level of physical structure within what is usually a comparatively homogenous, featureless subtidal habitat. Additionally they are highly productive systems (from both the seagrass and the associated algae) and so provide potential food and shelter for a wide range of organisms. Many studies have demonstrated that seagrass beds have a richer associated community than surrounding soft sediments, including invertebrates living in the sediment and on seagrass blades, larger mobile invertebrates (e.g. crabs, cephalopods), and certain fish that shelter within the meadow. This is perhaps not surprising as seagrass clearly provides a complex structure within which animals can hide from predators, and also provides completely new habitats (e.g. the leaves) that will host species not found in soft sediment. For example, all invertebrates recorded living in soft sediments off Hong Kong were also present in adjacent seagrass beds, but 48 additional species were only found associated with seagrass. However, the structural complexity of the habitat may not be the only factor influencing this boost in species diversity. Much richer community developed in experimental treatments that also included seagrass detritus than those with simply artificial leaves. Small invertebrates required the provision of food and showed little dependence on solely the seagrass structural characteristics. Seagrass beds have an important role as a nursery ground for the juveniles of commercially important fish species. For some species, the physical habitat is key as a shelter from predation, but other fish are attracted to seagrass beds due to their supply of food in the form of invertebrates. Some fish are only found in a certain habitat, such as seagrass beds. These are termed [ Select ] ["facultative", "designated", "obligate"] inhabitants, and would disappear with loss of habitat. Other fish use the bed out of 'choice' at certain times of the day. These are known as [ Select ] ["obligate", "facultative", "designated"] inhabitants.
obligate, facultative
Phytoplankton productivity is much less than that of macroalgae (X), but total phytoplankton productivity is far greater than that contributed by macroalgae (X) .
per unit area, on a global scale
Keystone predators, in this case starfish, exert (X) therefore (X) species richness in their rocky shore communities. The removal of the keystone predators leads to (X) competition for space among the prey species.
top-down control, increasing, increased