| What can you say about calanus | Does NOT have 8 legs |
| What is advection?
What determines zoo plankton distribution? | Zooplankton distribution is determined by physical and biological factors
Advection – how currents and other processes move water and the organisms in water.
In other words advection is the physical environment
The red current (atlantic current) moves heat and plankton up to coastal norway.
Climate change leads to more warm water coming from the south.
Greenland coats gets cold water from arctic - that’s way greenland is so much colder.
The coast are more rich in nutrients and the open water is momre oligotrophic. no arctic species on norwegian coast. But we don’t sea english and french species either. |
| Vestfjord and porsanger fjord | Vestfjord – many cod (very dependent on calanus populations. Red area is reproduction area for cod.
The calanus in lofoten are from the black areas and the norwegian sea.
Pordanger – warm water sneaks around the coast and hets up the outer area but the inner area is very cold (arctic). Can have minus degrees in may – but is also very productive. Remember ekman where the water comes in and out (depenndent on wind and weather) but usually comes in on letft side.
Outer areas have a lot of calanus, inner area has a lot of smaller zoo plankton species. (Big species prefer bi deep fjords and coastal areas.). |
| Where in the water column are zooplankton most abundant? | Epipelagic – upper 100 - 200 meters. (light). Much higher zoo plankton biomass
We often see a peak in zooplankton concentration just below where the chlorophyl is
some zooplankton migrate up and down
Mesopelagic – also important for secondary production. A lot of materiall sinking down with little ligt. Twilight zone.
Deeper zooplankton lives off of things that fall down or epipelagic species that migrate up and down.
We rarely take zooplankton from below 1000 meters. |
| Who are more active later in the season? | smaller copopods are more active later in the season.
pseudocalanus are much smaller than calanus. |
| How does the food chain look in pelagic environments? | Phytoplankton bliver spist af microzooplankton som spises af mesozooplankton.
DOC kommer fra døde plankton tror jeg
senere på seasonen når der ikke er meget nærring tilbage spiser phytoplankton af zooplanktons lort.
der er også zooplankton på bunden der spiser fecal pallets. |
| What is the relation between size, metabolic rate and generation time | Small organisms - high metabolic rate, short generation time |
| what are nekton? | The ones that are actually swimming |
| What is the trophic role of meso-zooplankton | - connects lower and higher trophic levels (calanus very important)
- connects pelagic and benthic realms (pelagic benthic coupling)
- connects clasical foodchain and microbal loop |
| what is special about copopod defication? | Copopods have special way of feeding – fecal pallats. When they produce fecal matter they compress it very well – packaging machines – fecal pallets. They concentrate the output. They have a membrane around which inhibits bacteria from outside to eat it and it sinks faster. |
| Are zooplankton only herbivors? | Zooplankton are not only herbivores.
Zooplankton fragmentate particles and release carbons, reduce sinking rate when upping surfacearea. Other zooplankton species eat the poc. |
| where is eufotic zone deepest sea or coast and why? | Deep sea
Euphtic zone is deeper at sea because there is less primary production so light travls deeper. And less runoff from glaciers etc. |
| When are physical parameters and when are physical parameters determant for distribution of zooplankton? | The ratio between swimmming speed of organisms and water movement. If water movement is > swimming speed physical is dominant. |
| what are the different scales of processes? | Overview of scales of processes:
Macro scale - thousands of km (tropical gyres, north-south gradients, continental upwelling)
Meso scale physical – coastal upwelling tides and so on (smaller gyres, 10-100km months to years)
meso scale biological - Growth and production – life cycles. Life cycle is decided by the season. life cycle varies a lot with latitude.
Coarse – inbetween
Fine – a lot of behavior is fine scale moovement
Physics dominate on the larger scale |
| What is patchiness? | means that organisms are distributed unevenly
Abundance can vary a lot with distance from where you start measuring.
Pathiness is not random, not orgnized – non random distribution
Non random distribution |
| What is fine scale patchiness
What can cause fine scale patchiness | Fine scale patchiness happens because of behavior
Predation on plankton can lead to patchiness. When fish stop and feed in one area for instance
Reproduction – big batch of eggs is produced in one area and the larvae will live close to each other.
Many species also aggrigate when mating.
Fish schools also lead to patchiness.
Also physical processes and the smaller scale. Larvae hatched in one area will be displaced by physical parameters. Will be spread out. Copopods has few eggs compared to fish. |
| What are thin layers? | In undisturbed seas without turbolation bays and fjords and so on, we tend to have nutrient, bactirial layers, phytoplanktopn layers that can be very thin because of densit. They attract other organisms. Forms layers.
Down left – upper mixed layer we have phytoplancton and the zooplankton follows. The laer mooves slowly downwards. Antoher layer below the pycnocline – another stage or population.
There are both physical and behaviral processes operating around thin layers |
| Explain the typical pattern of the diel vertical migration (DVM).
What time scales are we on?
Which organisms usually do this? | Typical pattern:
Upward moovement at dusk when sun is setting
Around midnight – plankton will spread
Dawn: mooving down again.
Common in copopods, krill amphipod etc.
Young copopods are to small to swim up and down and can therefor only participate in onthogenetic migration
This occurs all year around – but clearest in spring and summer – productive seasons.
I think the idea to go up - get food, go down - avoid predators.
most likely response to light that triggers it. |
| What are possible explenations for absence of diel vertical migration (DVM) | We expect the blue circle:
Dark – knight light – day.
The orange cases are different – just spread out. Especially the ones in august and september are weird.
DVM – diel vertical migration
Can be explaned by other factors
food avalability - is there any point in mooving up if theres no food there
Predetor occurance – you don’t want to migrate to the top if theres a lot of predators there. Some copopods can see fish shadows above them 5 – 10 meters. And can also to some extend smell them.
Mabey its also different water masses
Seasonal effect. Some seasons it makes more sense to migrate down. |
| What are the three types of migration that zooplankton do? (VEND TILBAGE TIL MIG) | Diel vertical (Up and down during night and day)
seasonal (Up and down during summer and winter)
Ontogenetic (different life stages on different depths) |
| Explain the seasonal migration of calanus
What differences are there with lattitude and where is the line drawn?
Why do they do the seasonal migration? | Seasonal migration:
During winter calanus is usually deeper down.
The juviniles migrate down towards the end of the season. And migrate up to mate towards the end of winter.
North of lofoten they only have one generation each year, and south they have several generations each year.
Copopods in the north migrate down to overwinter to avoid predators. Deeper waters is usually much colder with the depth. They keep metabolic rate low. Currents are also slower in the ddep water.
They somehow sense the change and migrate up again in early spring.
It is common for them to enter a resting stage (diapause) in the deep.
at depth they can keep metabolic activity very low.
Whats the point?:
at deep depths advection(skubbet rundt af strømme osv) is limited because of few currents.
fewer predators at deep depths. |
| What is the ontogenetic migration? | Ontogenetic migration:
Different stages (life cycle) at different depths.
Early life stage already have food and don’t need to feed. Don’t need to be at surface
Intermediate larval stages – to weak to swim up and down. They don’t search up and down for food. cannot take part in dial-veritical migration They are not as deep as shown in figure. |
| What are meroplankton? | Meroplankton – are only plankton in some lifestages. Often bentic organisms. Lives in free water from days to weaks and feed of phytoplankton blooms. F.eks. jellyfish, sea stars etc
Ophioplutus is brittle star larvae: as it sinks the early apendages are resorbed and it turns into sea star. |
| What is the difference between Ultimate cause, proximate cause and result of DVM? | Cause – why they do it
Proximate course – whatever triggers it (light for instance)
Consequence – consequences for populations and ecosystems. |
| What are the causes (ultimate for DVM)? | DVM - diel vertical migration:
Causes: what makes it selectively adventatios to choose a certain migration strategy.
Three different possible causes:
1 - avoid visual predators:
Go to or stay in the top to search for food. When the predation risk is to great go down. Tradeoff between food avalability and predation risk.
2 - save energy
lower metabolism at deeper depths – colder water.
3 – Facilitate horizontal movement
plankton cant really swim horizontally but changing your position in your water you can be transported. It makes it possible to moove horizontally by going up and down |
| what trigger mechanisms are proposed for diel vertical migration DVM? | Light intensity
Many have photoreceptors that can detect small changes in lightintensity
Gives information about depth, time of day and determines day cycle and seasonal cycle.
Linked to predation risk and primary production
Starvasion-satiation model
When hungry migrate up |
| What are some of the consequences of diel vertical migration? | Phytoplankton get time to recuperate
Energy bonus for the migrating organism (eve if not the reason)
Carbon flux in the system – vertical active transport of matter down.
Genetic mixing of populations. Different speed of migration leads to seperation of closely related organisms. |
| What is the ladder of migration? | Different species have different depths for the diel vertical migration? not really sure.
Different species have different habitats and depth ranges. Som pelagic species never og to the surface, but still migrate. It must be assumed that these migrations are not triggered by light, but are feeding migrations, where they feed in the upper layers of their habitat, where there is more food. |
| How can zooplankton increase contact rate with food particles? | By mooving vertically they may encounter new patches both by the moovement but also because currents can transport them to new areas.
They (copopods) can also swim around in search for motionledd particles |
| What does contact rate (Z) depend on?
This is both important for fish larvae but also for copopods like calanus. | 1 - swimming speed
2 - abundance of prey
3 - available search area (The distance a predator can sense pray from also matters.
Polution and toxins act on the sensesory system and can decrease predators or gracings organisms aility to find food. ) |
| Are prey safer staying still or swimming around? | Typically only maximum speed matters for the equation.
This means increasing total speed for both pray and predator leaves to highest contact rate.
Pray are therefore safer by keeping still. |
| Do cod encounter more or less prey with turbulance? | Swimming speed and turbolence:
Cod larvae ingest more up to a certain level in turbulance. Contact rate is higher with more turbulent until to much turbolent. |
| Which ways do copopods identify food particles? | Search radius depends on on senses of predator and senses are therefor important.
main senses for identifying food are:
Photoreceptors - light
Mechano receptors
Chemoreceptors - taste |
| Photoreception | Photoreception is most common in vertebrates but they also have them.
They can sense different wavelenghts and different tyes of uv light.
Bioluminescence is important in deeper organisms. |
| What is mechanoreception, what are examples | Mechanoreception – picks up flow patterns from pray
Sidelinjeorganit – lateral line system
Tentacles with colloblasts in ctenphora cnidoblast in cnidaria |
| chemoreception | Big in the sea.
They can sense hormones pheremones, aminals caught can release fear pheremones
plankton can sense gradients in molecules and move towards the source |
| Which is the most important variable of contact rate (Z) for grazzers? | Prey concentration
They can switch between preffered prey when abunsances change.
For instance untill bloom copopods might feed on ciliates but switch to flagelates during bloom. |
| What Type of climate do we have en tromsø?
Differneces in copopods from temperate and arctic?
What is boralisation? | it is defined as arctic but more similar to temperate like loofoten.
Arctic – copopods are larger, grow slower – longer life cycle, more oil, shorter productive season
Boralization –arctic is becoming warmer and more temperate |
| Name some effects of temperature in sea | Effect of temp on animals differ between land and sea
Temp in sea never below –1,8.
Many have anti freeze compounds in both freshwater, sea and land. Long chained fats are more solid therefor more short chained lipids in cold water.
Organisms are adapted to low temps. It’s the shortness of primary production periods are the main problems for animals up here. But the seasons are more predictable north than further south – easier to adapt when enviornment is more predictable. Then if the enviornment changes its really hard to adapt.
Population growth is also more syncronized with these seasons up here. |
| When do smaller and when do bigger copopods peak in abundance and why?
Name some small and some big copopods and how they spawn
what is capital breeding? | Larger copopods peak earlier in the season f.eks. calanus species. Take advantage of spring bloom
Smaller copopods grow later and are dominant in later part of summer. They are more affected by temp. Can feed from broader spectrum of organisms. Population is very much reduced over winter.
Pseudocalanus (small) only make 100 egss * female^-1. Carry egg sack that protect from predation.
Calanus > 1000. freespawning
Acawtia 800-1000 eggs. Freespawning
The two latter need a few generations for population to get big – later bloom.
In arctic they use the saved lipids to reproduce – capital breeding – using resorts from last year is true for many arctic copopods. (psedocalanus) |
| In copopod development how many stages do they have until they are grown | 6 napuli stages and 6 copopodite stages.
First few stages they get lipids and proteins from mother in eggs.
Length of generational cycle is very dependent on temperature. slower growth at lower temps.
These development numbers are under the assumption of enough food avalibility. |
| What are the influences of nutrients on copopod and appendicularia reprodoctive output and growth? | Copopod: more nutrients mean more lipid incorporation which makes for bigger eggs and laravl survival increases.
Appendicularia: more nutrients - energy allocated to reproduction more than growth. when appendicularia have a lot of food they have shorter life cycle and bigger gonads |
| How do big species lifecycle look compared to small | Big species – longer development time.
Calanus in arctic – life cycle more than one year for moest species. Each individual overwinters multiple times. They need a lot of lipids to overwinter. |
| Explain the match/mismatch theory | Basicly if cod larvae spawn at the same time as bloom there is a match and good conditions for the larvae, if not there is a mismatch and bad conditions. It is often temperature that determines when the bloom arrives and therefor if there is match or mismatch
First curve is fish eggs
Second curve fish larvae
Larvael food – third curve
When the larvae overlap with food – match. Otherwise mismatch. Match gives good conditions for cods. Bottom up explnation for cod survival.
Early feeding conditions are important for the cod larvae.
Even with good feedconditions a lot die - predation and canibalism.
But good cod years can be explained by match.
Fish arent that influeneced by temp – but zooplankton really deped on temp. Cold spring – mismatch. Very hot spring – mismatch. You want the bloom on exactly the right time. |
| What are some adaptations to seasonal fluctuations in copepods? | Three major adaptations to overwintering:
Dormancy – lowered basic metabolic rate and less activity. (Small copopods enter dormancy before production season ends because of low survival rate). generally dormancy starts earlier in higher latitudes.
They exit as juveniles. Depending on stage they can go from c4 to c5 which has to happen before reproduction.
That’s why cold spring can give slower development – and create mismatch.
Migration to deeper layers - in the fjords its cold deep down.
Calanus overwinter deeper down with increasing fish populationsize it seems.
Lippid storage high enrgy pr weight. So lipid is the most efficient way of storing energy. Benthic organisms (bigger) can also store carbohydrates and stuff |
| Seasonal cycle of calanus | check the statistics |
| Lipids and overwintering | Different species of calanus and other copopods use this.
When they get close to overwintering they neer max lipid capacity
Calanus hyperboreus – the biggest calanus is often seen in polar basins and deep arctic fjords but we also find it here.
Pseudocalanus
Also stores lipid. More than one generation pr year.
Can allocate a lot of energy to gonads and reproduction (spring and summer) or invest in lipid (late sumer and fall) depending on time of year.
pseudocalanus on picture. here you can see how much oil sorage fylder in winter compared to spring |
| What are some possible consequences of borealization of the arctic | Borealization - climate getting more temperate
Consequences:
-Productive season gets longer
-body size decreases (you don't need to be big and store a lot of lipids when it is warmer)
-lipid pr individual decreases
-(These two above might be bad for birds whales etc)
- life span will be one year instead of multiyear because of longer productive season
- population turnover rate increases (doesn’t nesesarilyy mean higher biomass. But with more primary production it could be so)
- total lipid production increases |
