| What characterizes posanger fjord? | - Large - 100 km long, 15 - 20km wide
- depths outer: 300m inner: 110m (inner also seperated by sill)
- influence towards barrents sea influenced by atlantic water
bottom temp: outer 5, inner: 0--1,8
- salinity gradient from outer(lhigh) to Inner (low) do to river runoff
Two sills: Outer(180m), inner: 60(m)
- semi closed system with influence from atlantic water (outer and middle) |
| What was measured with the CTD? | Physical proporties:
depth, temperature, salinity and fluorescence
find depth and places of maximum flourescence |
| What was measured with the neskin bottle? | Niskin bottles are attached to the CTD, which sampled seawater at different depths while the
measuring was done.
You then meassure chlorophyl using a fluorimeter. After adding HCL you can the meassure the pheophytin. I think this is to subtract this pigment because it is not chlorophyl? VEND TILBAGE TIL MIG |
| How does the forel ule scale work? | You compare the color of the sechi disc with colors on the forel ule scale. It helps determine biological matter in the water |
| How did we collect zooplankton? | with a plankton net with a cod-end (to keep the plankton in) with 2 liters
volume and weight was attached to the bottom. Sampling started at 10 m over bottom. |
| How did we meassure the grazing of zooplankton on phytoplankton? | Gut flurescence |
| What was the aim of the grab sample? | The aim of the grab samples was to determine the spatial distribution of different functional
groups of the benthic community and compare this data with the stomach data from predatory
fish. |
| Where did different species of zooplankton dominate? Why do you think? | Outer - calanus finmarchicus - i think out here the water is warmer and therefor
inner - pseudocalanus
middle - cyprid naupili
Outer - calanus on naupli (bigger proably eaten during winter)
inner - calanus C2-C5. more adult in inner
They also found more calanus under the chl max. - might also be feeding on dedritus etc. |
| What did the grazing show? | Much higher grazing in the warmer middle part than in the inner part. 80 times more grazing. Probably because of temp |
| Where was stratification strongest | Inner part because of freshwater. |
| Where was flouroescence in water highest?
Where was the lowest? | Middle - fairly mixed upper 100m. Even distribution of nutrients and phytoplankton.
- nutrients from river runoff
- upwelling because of atlantic warm water coming in.
Lowest was in inner - very stratified, low temps. |
| What explains some of the flourescence abnormalities found? | Zooplankton might feeding on the ones in the top which could cause decrese of chl in top.
sinking of phytoplankton might contribute to subsurface max. |
| How could we see that we were in the early bloom? | Many diatoms. very few dinoflagelates. |
| Why was the chlorophyl not highests in outer part? | Normaly temp is very determing for chl. But the middle had most. Probably because mixing septh was still very deep so temp not as important.
They also found that there wasnt big dif in temp between outer and middle.
Maybe also nutrient availability - more in middle because of rivers. They found they were nutrient limeted in dilution experiment. |
| In which dilotion would you expect the highest growth rate?
What more did they see in this experiment? | The one that is most diluted to increase space between predator(zooplankton) and prey(phytoplankton).
They found increased growth with more nutrients - nutrient limited. |
| Why were polychaetes so abundant? | Probably because of soft bottom
We also saw a lot of molluscs. Both mollusc and polychates increase when king crab is introduced. |
| How was salinity and temp correlated to species richness (benthos) | Positively:
More in outer - higher salinity and temp. |
| How was species richness in the three parts of the fjord?
What were the differences in species composition? | Outer highest, inner lowest.
the outer part is largely dominated by cod (67%), the middle part is less dominated by one species with northern
shrimp (44%) and cod (20%) and the inner part is strongly dominated by Northern shrimps
(76%).
Cod in outer were larger than middle probably because of better food availability. |
