EEMB 158 MT
Habitat compression
When local population is forced or restricted within a set boundary, to accommodate more species. **decrease in habitat range
Climate forcing
changes in radioactive balance - the largest forcing comes from an increase in greenhouse gases from industrialization
T/F: A decrease in pH leads to a reduction in calcification rates for all calcifying organisms
False
T/F: PIC is produced through the process of photosynthesis and forms the biomass of a cell
False
T/F: Production of PIC is coupled with export of PIC
False
How do animals acclimate to warming?
- acclimation is fast & their aerobic scope can decrease dramatically BUT its bad for long-term adaptation as metabolic trade offs (e.g. less energy for reproduction if temperature increases exceed the rate of adaptation) could result in a decline in ecological fitness
Which process of the nitrogen cycle occur under anoxic conditions
- annamox - denitrification - N2O production as a byproduct of N2 gas formation
Coccolithophores
- calcified phytoplankton - Emilania huxleyi = most common species that forms huge blooms - central to the global CaCO3 budget - huge blooms in northern & southern hemispheres
Adaptations for organisms in low-oxygen zones
- developed to take up, transport, and store oxygen to maintain aerobic metabolism includes: a. changes in group coordination, maximum group size, population structure in fish schools b. decreases in scope for activity by decreasing maximum metabolic rate (fish may become less active to conserve energy or more active to reach an environment with higher O2 levels)
Responses in ectotherm fish
- ectotherm means they do not produce heat to maintain a constant body temperature (meaning body temperature is a direct function of water temperature) - in almost all ectotherms, any increase in temperature causes an increase in basal energy & thus oxygen requirements
Responses in endotherm fish
- endotherm have warm muscles through a well developed vascular heat exchange system & high levels of myoglobin in red muscle which allows them to maintain internal temperatures of 20°C above ambient [evolutionary advantage to increase the delivery of oxygen to the mitochondria by myoglobin] - climate change including shifts in temperature-mediated oxygen availability could impact spawning areas & even lower the carrying capacity (seen with tuna)
What are the primary causes of sea levels rising?
- glaciers & ice caps melting (sea level rise by 0.5m) - thermal expansion [expansion of warming waters which was a main factor to sea level rise in the 20th century & currently accounts for more than 1/2 the observed rise] - ice sheets [the vast reserves contains billions of tons of frozen water & if they melt sea levels will rise by 64 m]
Stratified temperature profile
- has a mixed layer, then thermocline, and then the freezing deep ocean - low nutrients at the surface (since no upwelling) - favors K strategists
Temperature
- heating of atmosphere and ocean is not uniform, which in turn results in winds and currents - the stronger the gradient, the stronger that wind and current - the re-distribution of heat also involves hydrological cycle, hence drives patterns of evaporation and precipitation - changing the heat balance will affect weather and climate
Oxygen Minimum Zones (OMZ)
- hypoxic regions of ocean sandwiched between upper and lower oxygenated layers [typically found at intermediate depths 1000-1500 m] - formed because of weak ocean ventilation (which limits the supply of oxygen to depth) & high respiration which consumes oxygen - have very low pH (CO2 is released in reminieralization) and reduced conditions
El Nino
- intrusion of warm nutrient-poor water along the coast of Peru & this water is less dense than the Peru coastal current (warmer & less saline): nutrient poor layer up to 30m deep - coastal winds may or may not persist., but because the nutrient-poor upper layer is so much deeper than usual the upwelled water comes from above the nutricline & is low in nutrients [THIS is a problem for productivity bc this can cause a decline in catch & devastate local economies] Ex: - when El Nino occurs it can impact guano birds who have limited ability to fish at depth - weaker simmers & divers will be unable to find food so they'd perish THEREFORE see a decline of immature guano & in severe El Nino events can see significant numbers of adult birds decline as well
Mixed temperature profile
- is all just one temperature - high nutrients at the surface that supports phytoplankton growth - due to upwelling where wat4er from the deep comes up bringing with it nutrients that were stored there - favors R strategists
Endosymbiosis
- longer term process by which an organism actually lives within another organism & eventually that organism evolved into an organelle (e.g. mitochondrion) - hypothesized that a series of endosymbiotic events enabled the evolution of eukaryotes SO possibly a major mechanism of macroevolution, allowing organisms to acquire a major new function by incorporating the gnome of another lineage into itself [gave rise to red & blue algae which gave rise to groups of dinoflagellates) [slide 76 = evidence]
What affects calcification & who undergoes calcification?
- marine calcifies a. autotrophs (coccolithophores, green & red algae, calcareous, dinoflagellates) b. heterotrophs (pteropods, foraminifera, fish, gastropods, corals, echinoderms crustacea, sponges) factors affecting calcification: - nutrients - temperature - pressure - light - photosynthesis - omega (Ω) - bicarbonate [HCO3 (-)]
Which process of the nitrogen cycle occur under oxic conditions
- nitrification - nitrogen fixation
The nitrogen cycle
- nitrogen fixation = cyanobacteria have a gene that produces an enzyme that can actually fix nitrogen gas into a dissolved form of nitrogen thats bioavailable to phytoplankton (organisms that convert N2 gas to ammonia through fixation & that ammonia is easy to use by organisms to form organic matter) - catabolism = release of compounds as a result of metabolism (ammonium through nitrification is converted to nitrite then nitrates through several oxidation steps) - denitrification = conversion of a nitrate to a nitrite & then production of N2 gas with nitrous oxide as a byproduct - assimilation = production of nitrate into ammonia
Why is oxygen declining?
- ocean warming is decreasing the solubility of oxygen gas in seawater - increased stratification of the surface ocean reduces the O2 supply to depth and thus concentration of dissolved O2 in the ocean interior
OMZ impacts on the nitrogen cycle
- oxygen availability affects remineralization or organic matter --> the cycling of nutrients through the water column (e.g. N, P, Fe) - in the surface ocean which is oxygenated, fixed nitrogen ends up as nitrate ions (NO3) - in anoxic parts of the water column where dissolved O2 is depleted, denitrification where NO3(-) is converted into N2 by microbes & is an important mechanism of nitrogen loss to the atmosphere and thus central to the nitrogen budget - anaerobic remineralization of organic matter & anaerobic ammonia oxidation (anamox) using nitrite (NO(2-)) lead to a loss of bioavailable nitrogen through the formation of N2 & production of N2O - progressive deoxygenation of OMZ is expected to increase the volume of water where denitrification and anammox occur & increase production of N2O from nitrification leads to increased nitrogen loss from the oceans
Why is pH important?
- pH affects enzyme activity, substrate speciation, charge on macromolecules that control biomineralization, crystal size, structure, and crystallography - need to control pH for things like intracellular compartments (7.1 and 7.8) & calcification reservoir (>>8.0) - metabolism produces or consumed H(+) at rates that could change cytosol pH by a unit in a few seconds
PIC
- particulate inorganic carbon - interchangeable with CaCO3 - process = calcification
POC
- particulate organic carbon - interchangeable with biomass or sugars - process = photosynthesis
CO2 exchange between the ocean and the atmosphere
- photosynthesis fixes inorganic C (CO2) into organic solutes and particles with a corresponding decrease in the partial pressure in the ocean surface: driving force for the invasion of CO2 from the atmosphere into the ocean - calcification is a CO2 source on ecological time scales [because carbonate cant cross the membrane, bicarbonate crosses and dissociates into it] - heterotrophic oxidation of organic solutes & particles generate CO2 and potentially drives a flux of CO2 from the ocean to the atmosphere - expor5t of organic material from the euphotic zone to the ocean interior and subsequent biological oxidation of the organic C leads to an inverse concentration gradient in inorganic C [inorganic C below the upper 500 m of the ocean > than that at the air-sea interface
Biological & microbial carbon pump
- play a major role in sequestering and locking away carbon from the atmosphere [storing it in the deep for long periods of time]
R strategists
- prefer mixed temperature profiles - fast growing & multiplying - vacuolated - glacial (opal) Ex: diatoms
K strategists
- prefer stratified temperature profiles - slow growing - no vacuole - interglacial (carbonates) Ex: coccolithophores
How will climate respond to radiative forcing?
- the balance between the absorbed visible solar radiation and the outgoing longwave radiation determines the radiation budget of the earth - greenhouse gases absorb infrared radiation & release it back to the earth's surface thus increasing earth's energy balance and causing positive radiative forcing ultimately leading to warming
Topicalization of fish & consequences
- the increase in the proportion of warm water species - the migration of fish from tropical to higher latitudes is expected to have impacts on many trophic levels - Ex: a "topicalization" of fish populations with ocean warming is increasing fish herbivory & hence exerting pressure in kelp forests
What controls the CO2 sink?
- the ratio of PIC:POC - PIC:POC > 1.5 = source - PIC:POC < 1.5 = sink *the more CaCO3 that's exported the better as you want a higher ratio of PIC:POC because a higher ratio means better sequestration [see higher amounts at lower latitudes]
Effect of warming on fish
- tropical or polar fishes & fish in their early life stages are generally more sensitive to warming because they have narrower temperature tolerance ranges - fish respond to ocean warming by shifting their disruption (by 10s to 100s of km) - ocean warming is modifying the seasonality of occurrence of biological events such as spawning or migration [affects availability of prey due to changes in timing] - max body size may decrease
Effects of warming on metabolic performance
- warming decreases metabolic performance because rises in temperature decreases oxygen solubility & uptake, transport and delivery in marine organisms
Effect of ocean warming on marine birds
- warming is expected to reduce phytoplankton and zooplankton biomass & thus decrease the availability of prey for seabirds - detrimental impact on breeding success & body conditions because seabirds need to travel longer distance to find optimal feeding grounds which increases energy expenditure **can be beneficial in Bering Sea where transitions from cold to warm regimes may enhance productivity of piscivorous seabirds when young of large predatory species of fish are numerous enough to provide forage
Which of the following phytoplankton group would increase the pH of the surrounding water? a. dinoflagellates b. coccolithophores
- while both photosynthesis, dinoflagellates are non-calicifers while coccolithophores are calcifers - calcification decreases the pH due to the release of a proton that occurs during that process - photosynthesis takes up CO2 so we see an increase in pH SO dinoflagellates would increase the pH since they only photosynthesize & don't calcify
Why do we see an increase in CO2 concentrations in the deep ocean (especially the Pacific)?
- zooplankton respire which produces CO2 - since the Pacific Ocean is old, it makes sense that older waters which have been in the deep for long means they have experienced longer periods without photosynthesis so more respiration
Biomineralization
1. biomineralization compartment - separate from or partially in contact with the external environment where calcification can be tightly regulated (e.g. coccolith vesicle of E. huxleyi) 2. organic baseplate - surface onto which biomineralization occurs (typically beta-chitin) 3. amorphous calcium carbonate (ACC) - precursor of CaCO3 maintained in this state by silk fibroin proteins. Potentially delivered to biomineralization compartment once other components are in place 4. silk fibroin proteins - proteins rich in glycine, alanine, or proline that create an anhydrous gel-like environment preventing ACC from crystallizing 5. acidic polysaccharides - sulphated biomolecules that ring the crystal nucleation site. They create a poly-anion field that supersaturates Ca(2+) ions at the nucleation point 6. acidic proteins - proteins rich in acidic residues found at the crystal nucleation site. Carboxylic groups bind Ca(2+) ions in an ordered manner initiating crystal growth
What's the relationship between pH and hemoglobin affinity for oxygen?
A drop in pH lowers affinity of Hb for O2 ** animals carrying blood with high affinity for oxygen have a low P50 (the partial pressure of oxygen at which blood is 50% saturated) whereas those with low P50 are more tolerant to hypoxia
Is this adaptation or acclimation? An increase in basal oxygen demand and a decrease in aerobic scope
Acclimation
Is this adaptation or acclimation? A shift in phytoplankton physiology towards a cell size that can uptake nutrients more effectively under low nutrient conditions
Adaptation
Is this adaptation or acclimation? Generational trend towards an increase in fish herbivory
Adaptation
How does ocean acidification occur?
Atmospheric CO2 diffuses through the water and becomes dissolved CO2 and reacts with H2O to make carbonic acid which dissociates into bicarbonate ions and protons which increases the acidity (decreasing pH) *bicarbonate can dissociate into carbonate ions and 2H+ but due to how acidic that is, the equilibrium will push to the left thus decreasing the overall [CO3(2-)]
Between diatoms and coccolithophores, which group would likely thrive in upwelling regions? why?
Diatoms are likely to thrive in upwelling regions because they are r-strategists meaning they are fast growing and usually found in mixed temperature profiles. Those mixed temperature profiles usually occur where upwelling events happen and water from the deep comes up, bringing with it nutrients that were stored there and that increases the nutrients at the surface allowing for the fats multiplying strategists (diatoms) to rapidly grow
Vertical disruption of CO2
Most of the anthropogenic CO2 is found near the ocean surface
Hypoxia
O2 concentrations typically < 60 (detrimental to most marine organism)
What is an example of a biotic process that could alter the correlation between CO2 and temperature?
Respiration from organisms that increases CO2 in certain areas
Why are CO2 and temperature typically correlated in seawater?
Temperature and CO2 are typically correlated due to the solubility pump, which is driven by temperature is one of two major pumps that control ocean uptake of atmospheric CO2 CO2 and temperature have an inverse relationship where waters of higher temperatures hold less CO, while colder waters hold more due to the solubility of gases in liquids decreasing with increased temperatures
T/F: Cyanobacteria will increase pH of the surrounding water more than coccolithophores during a bloom
True
T/F: A shallower depth for aragonite or calcite saturation implies more acidified water column
True
T/F: Calcification in coccolithophores has been hypothesized as a CO2 concentrating mechanism for photosynthesis
True
T/F: Low latitudes have a proportionately high amount of PIC export relative biomass production compared to higher latitudes
Ture
Causes of deoxygenation
a. Coastal environments - high photosynthetic rates and biomass production that fuel high rates of O2 consumption by bacteria in subsurface waters and sediments - loss of O2 from eutrophication by agricultural runoff or sewage discharge, leading to excessive production of organic matter that increases oxygen demand b. Open ocean - warming driven declines in oxygen solubility & reduced ventilation of deeper waters caused by enhanced upper-ocean stratification - tropical & subtropical latitudes, decline in O2 in the upper ocean are attributed to the shoaling of the thermocline depth - higher latitudes, hypoxia is governed by warming-driven changes in solubility, wind forcing and large-scale ocean circulation
Physiological impacts of hypoxia
a. can compromise vision in animals - photoreceptors & neurons have a high requirement of oxygen for oxidative metabolism - hypoxia can cause cell damage particularly when oxygen decline occurs fast and under strong vertical gradients in oxygen concentrations b. negative effects of hypoxia can be transmitted across generations and can trigger epigenetic changes expressed in future generations (even when offspring are not exposed to hypoxia) c. reoccurring exposure of low O2 can alter immune response, increase disease, and reduce growth d. can cause reproductive disruption in fish
What physiological processes are impacted by ocean acidification?
a. photosynthesis - photosynthetic carbon fixation increases or is unaffected by OA in diatoms & coccolithophores - lower pH = more dissolved CO2 for photosynthesis to promote growth = higher fitness - organisms without CCM (CO2 concentrating mechanisms) benefit from OA b. calcification - depth at which Ω means dissolution = precipitation - Ω > 1 means precipitation > dissolution - Ω < 1 means dissolution > precipitation c. many enzyme driven processes
Threats of climate change on the ocean
a. rising sea kevels - accelerating flooding of costal communities & drowning wetland habitats b. bleaching - warm-water coral reefs (marine biodiversity hotspots) could be lost if the planet warms by 2°C c. toxic algae - larger & more frequent blooms are making birds, marine mammals, and people sick d. habitats - lower oxygen levels are suffocating some marine animals & shrinking their habitats e. acidification - more acidic water harms animals that build shells such as corals, clams, oysters f. fisheries - disruption in fisheries affect the marine food web, local livelihoods, and global food security
The ability of the ocean to take up atmospheric CO2 is controlled by 2 major pumps, what are they?
a. solubility pump (solubility of CO2) - driven primarily by temperature [cold waters contain more gases so more CO2 & oxygen that do warmer waters] b. biological pump (photosynthesis, calcification, respiration) - controls the export of matter including carbon from the ocean surface to the deep sea floor
Climate change impact on: a. temperature b. pH c. carbonate concentration
a. temperature = increase in temp. (anomaly with places showing 0.2-6.6°C increases) b. pH = decrease in pH due to carbonate ions concentrations c. carbonate concentrates = decreases in concentrations (-20 to -35 mmols) - this is important because carbonate is utilized by many organisms in their physical structure - many organisms that make plates out of calcium carbonate so changes in physiology will have huge repercussions on planetary scales because these organisms are responsible for the fate of carbon long term (i.e. coccolithophores that are considered the largest carbon sink)
How long must you account for when discussing climate trends?
at least 4 decades
Radiative forcing
differences in incoming solar radiation vs. outgoing infrared radiation (heat balance)
Suboxic conditions
extremely low O2 conditions (typically <5) which is life-threatening to most marine life
Dead zones
hypoxic water bodies driven by eutrophication, caused by excessive nutrient pollution from human activities depleting the oxygen required by marine life in bottom & near-bottom waters
Anoxic conditions
lack of oxygen [causes death to most marine life since they depend on oxygen]
Adaptation
long-term, genotypic changes from natural selection
Which human-driven phenomena is likely to select for r-species?
r strategists are fast growing SO costal eutrophication during the rainy season will be selective of r species due to increased nutrients at the surface supporting phytoplankton growth
Source
release of CO2 (upwelling zones at the equator) - calcification usually puts CO2 into the system [on an ecological (short) time scale]
Sink
removal of CO2 from the atmosphere (polar regions where the deep gets formed) - photosynthesis usually removes CO2 from the system
Acclimation
short-term, phenotypic plasticity (occurs over one lifetime)
Aerobic scope
the difference between the max oxygen consumption and the basal oxygen needs *under optimal conditions, the difference is big
