What is the Raynolds number? Which value of R has which outcome?
Re = (a * v * ρ) / ɳ -> ratio of inert to viscous forces
a = length (m)
v = velocity (m/s)
ρ = density of liquid (kg/m3)
ɳ = dynamic viscosity (kg/m/s)
Inertial force (newtons second law)
Viscous force F = (ɳ * S * v) / a -> S = area
R>>1 : dominance of inertia -> turbulence flow
R<<1 : domiannce of viscosity and drag, laminar or no flow, diffusive boundary layer
How does viscosity affect the properties of water in comparison to air?
water viscosity > air viscosity -> less mixing, more stratification -> less temporal variability, steeper gradients
Compare different sinking velocities of two particles with different radius and different density
Stokes law:
-> radius*density difference*shape
-> sinking speed increases with size, relative to weight, and density, form drag is a bit less important
Which properties of solar light change with depth?
light intensity
wave length
Which parameters decrease with increasing depth?
temperature
light
pressure
nutrients
water flow
Where are siliceous sediment dominant?
Circumpolar Antarctic Divergence
What is the geotrophic balance?
Balance between Coreolis and pressure gradient forces (sea level, temperature, salinity), direction of flow is orthogonal to balance between pressure gradient and coreolis force
Which parameters cause the large-scale ocean circulation?
Wind stress on sea surface (wind-driven circulation): wind stress is transmitted downwards due to turbulence, internal friction in upper ocean -> increasing current angle with increasing depth (Ekman spiral) -> net transport to the right of the wind in NH -> gyre circulation
Solar radiation on earths surface is unequal -> on rootating earth, wind follows contours of constant pressure (geostraphic balance), pressure distribution changes -> three wind circulation cells in each hemisphere -> trade winds -> Ekman transport causes upwelling events
Buoyancy flux between ocean and atmosphere (thermohaline circulation): Saline cold water is denser than warm fresh water -> sinks down -> relatively saline water fills the void, cools, increases density -> northward warm water transport southward deepwater transport
Why is the ocean salty and not chalky, although the flux of Ca and HCO3 is much larger than the flux of Na Cl?
Because the concentrations of Na and Cl are conservative as they are not used up by any biological processes; Ca and HCO3 are used up during the process of calcification
What is the definition of the residence time of an element in the ocean?
The time it takes for the entire reservoir of this element to be replaced once (mean conc*ocean volume/inflow per year)
Order the following elements according to their residence time
a) Na, Ca, Si, Fe
b) HCO3, NO3, SO3, Cl
a) Na>Ca>Si>Fe
b) Cl>SO4>NO3>HCO3
How can elements be classified based on their vertical distribution? Why is there a difference between the Atlantic and the Pacific?
Conservative: slight decrease in subsurface, otherwise stable concentration throughout water column
Bioactive/-limiting: depletion in surface, highest concentration at ~1000m
Particle-reactive: stable concentration throughout water column in Atlantic, increase towards depth in Pacific
-> great ocean conveyor belt: deep water formation in North Atlantic, transport through Pacific, next contact with atmosphere (gas exchange) in North Pacific, transport back to North Atlantic as warm surface water
-> Pacific deep water is older and had more time to accumulate bioactive or particle reactive elements sinking down from above
Which of these elements are bio-limiting, conservative, particle-reactive?
Ca, Ba, N, P, Mg
Ca: bio-limiting
Ba: particle-reactive
N: bio-limiting
P: bio-limiting
Mg: conservative
Explain principles and drivers of the biological and physical carbon pump
biological pump: CO2 uptake by phytoplankton, CO2 release by respiration, transport of organic C to depth via sinking, release in deep waters by respiration
physical pump: driven by thermohaline circulation, CO2 uptake at higher latitudes due to deeper water formation, CO2 release in tropics due to higher ventilation/ equatorial upwelling
marien PP is conceptually distinguished into the two categories “new” and “regenerated” production. Explain both. Which form of inorganic N supports one and the other type of production?
regenerated production: recycling of released nutrients in euphotic zone by phytoplankton uptake, NH4+
new production: supported by external nutrient input e.g. N-fixation by diazotrophs, NO3-
Name the major difference between the biological carbon pump and the carbonate counter pump in relation to CO2 water-atmosphere exchange
biological carbon pump is driven by PP, i.e. uptake of CO2 and formation of OM (CH2O)
carbonate counter pump is driven by CaCO3-formation, i.e. Ca + HCO3 —> CaCO3 + H2O + CO2
difference is CO2 uptake/release and export products CaCO3 and CH2O
The N:P ratio of inorganic nutrients in the deep ocean (i.e. below the winter mixed surface layer) shows destinct deviations from the Redfield Ratio of 16:1, the so called N:P anomalies.
a) Which process is primarily responsible for the higher than Redfield proportions (N:P > 16:1)
b) Which two processes are primarily responsible for lower than Redfield proportions (N:P < 16:1)
a) Nitrogen fixation by diazotrophs -> supported by high Fe input and strong P depletion
b) Loss of N during remineralization (denitrification, respiration) when primary production is high
Assume that a phytoplankton bloom of diatoms and one of coccolithophores have the same biomass. Which bloom leads to strong reduction of CO2 partial pressure in surface waters and why?
A bloom of coccos would lead to a reduction of ppCO2 as they are using CO2 for shell formation while a bloom of diatoms would result in high respiration rates
What are the main requirements for life?
energy (ATP)
carbon (CO2, CH4 or C)
liquid water
various elements (N, P, S, Na)
What is the definition of chemosynthesis?
Process by which prokaryotes synthesize C3 (glycerate), compounds from C1 (CH4) compounds using chemical energy
Which two steps happen during nitrification?
1) ammoinia is converted to intermediate hydroxylamine, the nitrite by nitrosomonas and nitrosococcus
2) nitrite is converted to nitrate by nitrobacter
What happens during Anammox?
ammonia oxidation under anaerobic conditions: NH4 + NO2 —> N2 + 2H2O
What are the challenges for Fe oxidizing microbes?
low O2 conditions (anoxic, microoxic conditions), have to avoid being incrusted into Fe3+ minerals
What does generally happen during all CO2 fixation pathways?
Carboxylating enzymes links inorganic CO2 or HCO3 with organic acceptor molecule which needs to be regenerated in the following steps
What is the Great Plate Count Anomaly?
Microorganisms are the most abundant organisms on earth but only 1% can be cultivated
What is the difference between autotrophy and heterotrophy?
autotrophy: synthesis of nutrients by uptake of sunlight and chemical energy
heterotrophy: uptake of nutrients through organic matter (primary producers)
Which environmental conditions determine which pathway is represented?
oxygen sensitivity
temperature tolerance
requirements for metals (Fe, Cu, Ni, Mo)
used CO2 species
need for coenzymes
availability of reducing compounds
Why are key enzymes of the CCB cycle found more often at hydrothermal vents with moderte tempertures and key enzymes of the WL (CoA) cpathway rather at hot hydrothermal vents?
The CCB cycle has an upper limit of 70-75°C and functions under oxic conditions, while the WL cycle does not have a temperature restriction (even hyperthermophyles) requires anoxia and high abundance of metals
Which are the key enzymes of the CCB cycle?
RubisCO and Phosphoribokinase
Name one chemical redox reaction that can be catalyzed by microbes to gain energy from chemosynthesis
Acetyl CoA + Ferredoxin(red) —> pyruvate + Ferredoxin(ox)
Name two CO2 fixation pathways
Calvin Benson Bassham cycle, reductive CoA-pathway
Name and explain periods of light variation. Which effects do they have on phytoplankton biomass
diel (24h day and night)
diurnal (during the day, cloud cover)
seasonal (summer and winter)
lattudinal (equator and arctic)
phytoplankton biomass varies throughout year and regions: continuous in tropics, higher in spring in north temperate regions, peak in summer in north pllar regions
What factors determine light penetration in the water column? Does climate change effect light penetration?
Wavelength: PAR 300-720
attenuation coefficients of water, plankton, particles (turbidity)
-> climate change increases terrestrial DOC input (brownification of lakes and sea water) due to permafrost melting, more rain, increase of plant debris at higher temperatures
Name three important photopigments alongside with some characteristics
Chlorophyll: green coloured, absorb blue and red light, fluorescence maximum at 680nm, light harvesting
Carotenoids: red-yellow pigmented, absorb blue-green light, no fluorescence, light-harvesting and photoprotective
Phycobilin: red-pink coloured, absorb green-yellow light, fluorescence at 570nm, light harvesting
Name for processes/sources of DOM
glacial melting
rain
release of plant debris
weathering
What is a P vs. I curve? Identify regions A-E in the curve. What happens below and above Y=0?
Shows whether cell growth is light limited/saturated
used for quantifying and modelling of marine phyttoplankton productivity
A -> light limitation zone
B -> light saturation zone
C -> photoinhibition zone
D -> light compensation point
E -> lightt at max. photosynthetic rate
Y>0: net production
Y<0: respiration
How does cell physiology affect the P vs. I curve?
Reduction of antenna size: lower efficiency at lower irradiance due to reduced absorption but also less increase at high irradiation due to reduced photoinhibition
Improved RubisCO function: same efficiency at los irradience, higher efficiency at higher irradience due to increase in catalytic rate and decreased photoinhibition
Improved pigment composition: higher efficiency at lower irradiences due to utilisation of alternative wave lengths
What is the difference between photoacclimation and photoadaption?
Photoacclimation: phenotypic response, changes in pigment composition/concentration and enzyme activity.
-> maintains constant photosynthetic efficiency under varying light conditions
Photoadaption: genetic change (mutation/species selection), species have different pigments/enzymes/biogeochemistry at identical light conditions
What is net primary productivity and how can we measure it?
Net rate of organic matter produced = gross primary production via uptake of inorganic carbon - respiration
-> incubation in light and dark bottle with 14C and O2 incubation measurements
What are the physiological responses of an autotrophic cell to nutrient limitation? Give two examples.
Carbon allocation inside the phytoplankton cell (storage in mitochondria)
Extracellular release of OM
Explain three strategies of nutrient acquisition
The survivalist: high N:P ratio -> can sustain growth with limited resources via resource acquisition (proteines, pigments, enzymes)
The bloomer: low N:P ratio -> adapted for exponential growth, contains growth machinery (rRNA)
N:P near Redfield ratio -> balances growth and acquisition machinery
Name organisms that use biogenic materials to build up their hard parts
coccolithophores
pteropoda
foraminifera
diatoms
radiolaria
sponges
What are the four phases of a typical diatom bloom curve? How many days does a bloom ususally take?
Lag phase -> no diatoms
exponential phase -> growth
stationary phase -> maximum
declining phase
-> 21 days
What is the principle of Liebig’s law of the minimum?
Yield of plant mass is proportional to the amount of limiting nutrient (nutrient that runs out first)
What are the main sources and sinks of elements in the oceans?
Sources:
river
dust
hydrothermal vents
Sinks:
sediments
air-sea interface
Which groupes does the term “Macrophytes” include?
Phaeophyta (brown algae)
rhodophyta (red algae)
chlorophyta (green algae -> plants, sea grasses -> plants)
Name and explain factors affecting the light compensation point
Intensity of dark respiration: low if all cells are photosynthetically active (thin thalli e.g. crustose algae)
Intensity of photorespiration: low if CO2 uptake is efficient (particularly in green macroalgae)
What are the advantages of green macro algae like Ulva regarding of HCO3- accumulation?
Ulva can directly transport HCO3- into their cytoplasm with carrier enzymes. This allows C accumulation additionally to to transformation of CO2 to HCO3- by carbonic anhydrase
List four mechanisms that are used by marine macrophytes to prevent damage from excessive solar radiation
thick epidermis
cell walls with high tannin concentration
thermal dissipation
specialized amino acids
Which environmenttal factors typically determine the lower distribution limit of macrophytes in tthe vertical zonation on a shore? (2 options)
light exposure
air exposure
Which are the main factors determining the regional distribution of seaweeds?
Wave energy
substrate solidarity
salinity
nutrient availability
pollution
eutrophication
What does the dominance of a certain macrophyte indicate? What does the morphology of the thalli indicate?
Greene algae -> eutrophication, shallow water -> Baltic Sea
Brown algae -> cool/sunny/nutrient rich -> kelp
Red macroalgae -> warm/shady/oligotrophic -> crustose algae
Leathery/filiform/calcerous -> sensitive to herbivory/high productivity/early successional species
crustose -> insensitive to herbivory/low productivity/late successional species
Why does it seem as if an increase in Roseobacter bacteria would corelate with a decrease in phytoplankton?
Roseobacteria and Flavobactteria break down DMSP produced by phytoplankton to DMS and MeSH
bacteria are highly motile and have a positive sense for degraded phytoplankton/DOM
Why do whalr falls have such a high importance fore deep sea biological processes?
concentrated food input to deep seawhich is. usually nutrient deprived
one carcass = carbon sinking of 100-200 yrs per hectar at abyssal sea floor
complete degradateion is a matter of many years and includes all kinds all kinds of organisms from carnivorous fish and crabs to microbes and worms
Briefly explain the three stages of whale fall degradation
mobile scavengers remove soft tissue (hag fish/sharks/rat tail fish)
enrichment opportunist stages: colonization by dense assemblages of worms and crustaceans
sulphophilic stage: chemoatotrophic and heterotrophic microbal assemblages
Briefly explain the sponge loop and which role microorganisms tare playing
corals and algae produce mucus (DOM) -> uptake by sponges -> release of POM by sponges upon death -> uptake of sponge. POM by detrivores
-> 1/3 of sponge biomass is microbial (cyanobacteria, choanocytes, pinacocysts, archaeocytes)
SAR11 is among the most abundant bacteria in the ocean. Name some characteristics of this bacterial clade
Proteobacterium
25% of all microbial plankton
carbon oxidizing bacteria (DOM)
Aerobic
free living
chemoautotrophic
small genome (1-3Mb)
Name differences between bacteria and archeae regarding their habitat, cell wall, reproduction and metabolism. What can be concluded about archeae?
bacteria
archaea
Habitat
almost everywhere
extreme environments
Cell wall
peptidoglykan
s-layer, no peptidoglycan
reproduction
spore formation
no spore formation
metabolism
diverse
diverse and methanogenesis
archeae have metabolism of bacteria and replication machinery of eukaryotes
Whata are unique characteristics of the archeae Pyrococcus furiosus (“firenzied fireball”), nanoarchaeum equitans (“riding dwarf”) and Sulfulorus solfactorius?
P. furiosus: Hyperthermophiles -> fast growth at 80-103°C, optimum at 100°C)
N. archaeum: symbiosis/parasistism with bacteria, tiny cell, tiny genome (400Mb)
S. solfactorius: growth optimum at 80°C and pH=2-3, grows on sulfur, extremely stable enzymes
Why is the 16S rRNA extremely important for taxonomy?
it is a relatively conservative sequence that can be used to identifiy taxa independently from cultivation
What is the candidate phyla concept?
Bacterial clade with no cultivated representatives that have been discovered by metagenomic sequencing
What are special conditions in tide pools and how do they affect biological processes?
ppO2 increases during day time due to 2x photosynthesis (hyperoxia), decreases during night time due to respiration (hypoxia/anoxia)
How does white muscle tissue relate to anaerobic conditions? What is the problem with using anaerobic metabolism pathways?
muscle isn’t dependent on oxygen as it is only used for propulsion to make quick movemements BUT anaerobic mettabolism produces H+ alongside ATP and endproducts -> muscle gets sour
Which organisms dominate hypoxic zones and why? How can marine invertebrates survive seasonally anoxic periods in their benthic habitats? How does this increase survival time?
bivalves (A. islandica & A. borealis) due to their exceptionally high tolerance to anoxia
massive glycogen reserves
alternative anaerobic endproducts decrease metabolic heat production by 99%
-> 100x extended survival time by metabolic reduction, 3x extended by alternative endproducts = 300x longer survival time with same amount of glycogen reserves
Which procsesses happen when an organism is close to cell death under anoxic conditions?
Exhaustion of fermentable substrate
ATP and pH fall
vital cellular processes fail
membrane rupture
cell death
How can we determine, what fuels marine animals use for aerobic metabolism? What are advantages and disadvantages of alternative metabolism pathways?
Respiratory coefficient = CO2 formed/ O2 consumed
proteins: (+) more oxygen efficient than fats
(cephalopods) (-) can be less dense packed than fats
fatty acids: (+) less mass to carry, lower body volume, reduced friction -> energy expenditure
(turtles) (-) metabolic rate is not sustainable for a long time
Why and how do aquatic animals excrete NH3/NH4+?
high water solubility, low production costs compared to urea -> excretion via gills ion transporters, gas channels
Briefly explain phagocytosis in unicellular plankton
sensing of food particles -> engulfment -> food vacuole (phagosome) -> intracellular digestion via fusion with digestive enzymes (phagolysosome) -> exocytosis of undigested material
What is a model?
Simplified system of postulates, data, mathematical descriptions of an entity or state of affairs
What can ocean models be used for (3 options)?
Test hypotheses, concepts, ideas: causes of ice ages, mass extinctions, deoxygenation
Isolated observations into coherent context: reanalysis products, process studies (mesocosms)
Scenario simulations/predictions: consequences of human action
Explain how a realistic photosynthesis – growth – relationship differs from the Michaelis-Menten model
Michaelis-Menten model provides a relatively small curvature because it assumes photosynthesis = growth; other models take into account that unused photons are lost and cannot be recycled whereas unused nutrients can be recycled/ stay in the system -> Michaelis-Menten model represents growth limitation by nutrients while growth limitation by light has a steeper initial linear slope and more sudden saturation
What are discretisation issues of models?
Ocean is not uniform but homogenous, concentrations are affected by advection/diffusion/gas exchange/redox chemistry
____ dominate biomass in the ocean, but _____ dominate abundance
Prokaryotes…viruses…
What is the size spectrum of viruses and phages?
10^-8 – 10-6m (phages: 10-7 – 10-8m) so on the boundary between DOM and POM (0.2 µm)
What is the definition of a virus?
Tiny agents made up of DNA or RNA that require a specific host cell to replicate
Explain lytic vs lysogenic life cycle of a virus
lytic: phage attaches to host cell, injects DNA -> phage DNA circularizes & enters lytic or lysogenic cycle -> new phage DNA and proteins are synthesized and assembled into virions -> cell lyses, releases phage virions
lysogenic: circularized phage DNA integrates within bacterial chromosome by recombination (prophage) -> lysogenic bacterium reproduces normally (cell division) -> daughter cell has virus genes -> occasional excision of prophage from bacterial DNA & initiation of lytic cycle
What impact do viruses have in the ocean?
Kill bacteria -> release carbon (10 billion tons/day)
change host metabolism/gene expression (control)
gene transfer
Virophages are ____ (ssDNA/ dsDNA/ ssRNA, positive sense/ ssRNA, negative sense) viruses that replicate in giant virus infected eukaryotic cells and can integrate into the genome of host (eukaryotic) genomes and act as an immunity system against giant virus infection
dsDNA
What has led to the three-domain hypothesis in 1977? What were previous hypothesis of organism’s kingdoms?
rRNA as universal, conserved, variable regions that are phylogenetically informative and can be used for molecular analysis; previously: 2-kingdom hypothesis (1900s) with only animals and plants, 5-kingdom hypothesis with monera, protists, plants, fungi, animals
What are recognized issues with phylogenomics?
gene trees don’t always reflect species trees due to horizontal gene transfer, gene duplications result in paralogous genes, composition changes among genes, mutations
One current prevailing hypothesis is that the rise of the eukaryotes (eukaryogenesis) has a/an ____ (Algal/ Sponge/ Ctenohphore/ Archaeal/ Fungal) origin; whereby eukaryogenesis involved a chain of events that lead to this primitive cell establishing as a symbiosis with a bacterium which became the mitochondrium. Where do these ancestors come from?
Archaeal (Lokiarchaeota as gap-filling between prokaryotes and eukaryotes) -> from hydrothermal vents
Name the main characteristics that differentiate Cyanobacteria, Heterocontophyta, Prymnesiophyta, Chryptophytes, Dinophytes, Euglenophytes, and Chlorophytes from each other
Cyanobacteria:
chlorophyll, some heterocysts for N2-fixation
Heterocontophyta:
2 heterokont flagella, diatoms (epitheca/hypotheca Si-cell wall, Pseudonitzschia), silicoflagellates (internal Si-skeleton, only marine)
Prymnesiophyta:
2 flagella, 1 haptonema, coccolithophorales (CaCO3, Emiliana), prymnesiales (Wellenschaum)
Chryptophytes:
2 hairy flagella, no cell wall, barely dominant in ocean, small, Teleaulax
Dinophytes:
flagellates, “naked” (Gymnodinium) and armoured (Dinophysis, thick cellulose plates)
Chlorophytes:
green algae, equal flagella, ancestors of higher plants
Which are the functional groups of phytoplankton?
Phytoplankton, Zooplankton, Bacterioplankton, Mixotrophs
Which are the size classes of phytoplankton?
Pico: <2µm
Nano: <20µm
Micro: 200µm
Meso: <2mm
Macro: <20mm
Mega: >2cm
Which consequences do low Reynolds numbers have for phytoplankton?
laminar flow around particle, diffusive boundary layer, water sticks to cell, viscous forces dominate, sinking velocity follows Stoke’s law (Re < 1)
What are consequences of a large S:V (surface:volume – ratio)?
More molecules can encounter cell surface in relation to volume, cell can host more nutrient transporters in relation to volume -> small cells have higher affinity and competitive advantage in low nutrient conditions
Explain the terms protostomia, deuterostomia, bilateria, spiralia, ecdysozoa
proto-: mouth opening of gastrula stays mouth, secondary anal opening, spiral cleavage of cells
deutero-: mouth opening becomes anus, secondary mouth opening, radial cleavage of cells -> chordata
bilateria: bilateral symmetrie, triploblastic (ecto-, endo-, mesoderm) -> spiralia, ecdysozoa, deuterostomia
spiralia: animals that evolved with spiral cleavage of cells around axis -> annelida, mollusca, plathelmintha
ecdysozoa: process ecdysis (moulding) -> nematoda, arthropoda, tardigrada
What is functional diversity?
roles that organisms fulfil in different habitats and community compositions, based on traits that are essential for ecosystem stability
What trophic modes can you find in benthic marine ecosystems?
suspension feeders, predation, filter feeding, grazing
What does particle retention efficiency refer to in suspension feeders?
percent of particles that are retained by filter apparatus during one passage
Which of the two groups have a higher retention efficiency for particles <2 µm: sponges or bivalves?
bivalves have 100% retention efficiency at 5µm, sponges at <1µm
How does the sponge filter apparatus differ from that of bivalves?
bivalves have cilia in lamellae that are specialized on catchment and transport, sponges have filtration chambers with choanoflagellates
What specialized structures/organs do marine invertebrate groups possess to capture & ingest particle food (4)?
cilia, cnidocysts/cleptocnides, radula, choanoflagellate chambers, tentacles
Why are fishes paraphyletic and which groups belong to them?
not a common ancestor but similar evolution of several monophyletic groups:
Myxini (hagfish, secondary reduction of vertebra to chorda dorsalis), Petromyzonta (lampreys/agnatha, +vertebra), Chondrichthyes (Gnathostomata, sharks/rays/chimeras, +jaws), Actinopterygii & Crossopterygii & Dipnoi (Osteichthyes, swim bladder, skeleton, most diverse vertebrate taxon)
What is a main difference between cartilaginous and bony fishes? Name 3 consequences of this
cartilaginous fishes don’t have a swim bladder for reduction of specific weight (pelagic zone), enrichment of fat and oils in liver to ensure buoyancy, constant swimming with large pectoral fins as lift producing wings
Give at least three principal differences in terms of reproductive biology between teleost (bony) fishes in contrast to sharks and rays. What are the consequences for fishing on these types of fish?
bony fishes: large number of eggs
sharks/rays: vivipary (“placenta”), ovovivipary (eggs with embryo develop within female) & ovipary (eggs)
Consequences: (ovo)viviparous fishes have late maturity age and only few offspring -> vulnerable populations
What is convergent evolution? Give a marine example
Independent evolution of similar trait. E.g. streamline body shape
Why do fishes form swarms? Explain 2 reasons
Predator confusion, detection dilution (less spots where predators can find prey levy-flight of predators)
How much larger is the deep-sea habitat compared to remaining tropical rain forest? How are bony fishes adapted to this habitat?
1500x larger (25x larger area). Adaptations: bioluminescence (prey attraction/location), photophores on ventral side (invisibility against water surface), vertical swimming (decreased surface area from below), extendable stomach and jaws (food shortage), dwarf males (mating partners scarce -> stay attached)
Name some characteristics of cephalopods. What is special about their reproduction cycle? What implications does this have on the biological carbon pump?
gigantism in deep sea, chromatophores for colour changing (signalling/camouflage), arms & tentacles for prey/detritus catchment; generation time only 1yr -> one reproductive investment, then death (semelparous) -> mass spawning and death events -> huge amounts of biomass sinking fast to the seafloor during patchy events
What are main reasons for marine turtle declines in the past (historically) and in recent times?
Historically: direct exploitation because they were easy catch on long sea journeys; Now: bycatch
Name the orders of seabirds. What is an advantage of having wings?
Penguins, Albatrosses, Pelicans, Herons/storks, Shore/wading birds/skuas/auks -> inaccessible breeding sites
What are examples for management efforts to mitigate seabird bycatch on longlines?
streamer (tori) lines -> scare birds away, line weighting -> more rapid sinking of lines
How do marine mammals achieve homoiothermy?
decrease of S:V ratio by exceeding 1m in length + 50kg mass; insulation via body fat; high metabolic rate
Why are baleen whales so large whereas toothed whales are not? What about sperm and beaked whales?
Baleen whales: positive allometry in filter-feeding adaptations, energy efficiency increases with weight
Toothed whales: investment in biosonar (high costs), energy efficiency decreases with whales, sperm & beaked whales are large to push physiological limits for dive duration and depth
How does a decline in whale populations affect deep sea habitats?
Whale falls are stepping stones for gene flow, demographic exchange and spatial distribution of sulphophilic organisms that normally live at hydrothermal vents
What are the three main underlying principles of the hologenome theory of evolution? Give a holobiont example
symbiosis is ubiquitous across the tree of life -> presence of microbes
symbionts can be transmitted between generations
-> vertical (microbes in egg) + horizontal
microbial symbionts affect holobiont fitness
variation in the symbiont community aids in holobiont acclimation to environmental changes
-> corals: microbes in “skin”, allow corals to adapt to changing environmental conditions more rapidly than via mutation and selection
What are special characteristics of the Wadden Sea?
largest tidal flat system in the world, sediments supplied from sea, high productivity, many endemic species, important for migratory birds, fish nursery
Mention two important determinants of lower and upper (vertical) distribution limits of invertebrate species on many rocky shores. Name experimental approaches to detect these
lower: predation, competition upper: physical factors (dessication, wave shock)
-> removal/ addition/ replacement series, predator removal, direct observation of overgrowth competition
What are ecological and physical risks that climate change pose to intertidal habitats? What’s a consequence?
Ecological: more competition by opportunists, bioinvasions, increased grazing rates
Physical: de-/hypersalination, storms + increased wave action, warming
-> poleward migration of intertidal species
Briefly explain four types of reefs. Name two important traits of corals
fringing reef: grows seaward directly from shore
barrier reef: grow seaward separated from land (lagoon)
atoll: in open ocean, open lagoon in center, patch reef
-> symbiosis with unicellular algae for photosynthesis, ability to fix calcium carbonate (build skeleton)
Mangroves have developed unique adaptations to two challenging abiotic conditions in their environment. Name these two main conditions, along with specific adaptations to cope with them
salt stress: salt excretion via leaves, salt exclusion to prevent it from entering the vascular system
anoxic sediments: pneumatophores, prop/ kneed/ plank roots to gain alternative access to air
What are mesophotic reefs? How are these distinct from shallow/deep reefs?
habitat in the mesophotic zone (30-150m), inhabited by light dependent organisms BUT extreme light-limited conditions (adaptations), continuation of neighbouring shallow habitats (same species, different appearance)
What are the three dominant structural communities in the mesophotic zone?
algae, corals, sponges
What is the Deep Reef Refugia hypothesis (DRRH)? What are its limitations?
mesophotic populations can provide viable reproductive material for shallow reef areas following disturbances -> only tested on limited taxonomic, geographic, bathymetric, climatic basis
Are all mesophotic populations well connected to their neighbouring shallow populations? What might enhance/ inhibit connectivity?
potential of connectivity varies by location/taxa; enhanced/inhibited by larval supply, behavioural movement, phenotypic plasticity, local hydrodynamic patterns
Why are mesophotic populations important? Should we alter shallow reef management strategies to include mesophotic reefs? Explain why yes/no
Important because they could serve es reservoir to replenish biodiversity lost in shallow waters, but they also have their own unique biological communities that should be protected
Name some characteristics of the epipelagic zone
Photic zone in pelagic ocean, biodiversity reservoir, feeding grounds for endangered mammals, carbon sink
What’s the name of the ability of organisms to produce light, name 3 functions of this phenomenon in the deep sea and name a group of organisms that uses it for one or more of the 3 functions you listed
Bioluminescence -> prey detection/attraction, counterillumination, signalling -> Lantern-/ anglerfishes, cephalopods
What is the name of the vast extensive seafloor between 3000-6000m? What is the main pathway for food supply in this habitat? What interests do humans have here?
Abyssal plain; food: terrestrial vegetation, migrating deep-sea fish, large food falls; interest: Mn nodules
Name adaptations to life in the deep sea with respect to maintaining position, senses, feeding, and mimicry
Position: increased S:V ratio, flat shape, constant swimming, increased buoyancy
Sense: well developed eyes, lateral line, echolocation, colouration, transparency, silhouette reduction
Feeding: diel vertical migration, predation, cannibalism, extendable stomach, catch sinking detritus
Mimicry: sargassum seaweed inhabited by a number of organisms that mimic its appearance
Name and briefly explain three important environmental similarities of the Arctic and Antarctic?
low solar irradiance at high latitudes, negative net radiation budget, extreme seasonality in radiation budget (light availability), high albedo due to ice and snow, both poles are glaciated, short summers
What are dissimilarities between Arctic and Antarctica?
Explain the currents in the Arctic Ocean
Transpolar drift: current from new Siberian islands across North pole towards Greenland
Beaufort gyre: circulation towards Bering strait; little water exchange with Pacific because Bering strait is so narrow -> Inflow of warm water via Eastern Fram strait, outflow of cold water via Western Fram strait, increasing inflow of Atlantic water masses
Explain the characteristics of Arctic surface waters
stable surface water layer due to summer warming & freshwater inflow -> nutrient limitation; vertical thermohaline convection in Greenland basin in winter -> oxygen transport to deep Arctic ocean
Explain the Antarctic winds and circumpolar currents and how they affect surface and vertical currents?
Winds: east wind drift over pole, west wind drift around pole
Currents: Antarctic divergence below east wind drift, Antarctic convergence (polar front) below west wind drift (ACC)
isolated surface currents, weak vertical stability (downwelling at margin, constant upwelling at divergence)
There is 1µmol Phosphate in seawater. Which plankton species dominates?
the one with the lowest nutrient requirement
Which of the following statements are correct and which are wrong?
The biological pump increases nutrient regeneration in the surface waters
The biological pump transports food to the seafloor
The biological pump causes an enrichment of CO2 in deep waters
The biological pump is particularly active in the oligotrophic, tropical ocean
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Where are upwelling regions and what are their features?
at eastern boundaries and equator; high primary productivity and food web activity, high fish production, high carbon fluxes to midwater depths, especially old water masses at midwater depths, high oxygen demand & low supply (OMZ)
How can metazoans deal with low oxygen concentrations on long- and short-term scale?
Long-term adaptations: increasing gill/lung size, reduction of diffusion distance, enhanced oxygen uptake capacity of respiratory proteins, counter-flow principle, small body size, low metabolic activity, enhanced capacity for anaerobic metabolism
Short-term: increasing respiratory protein concentrations, faster breathing, low activity, metabolic suppression, moving away, only temporarily use the low oxygen habitat
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