student presentations

layout of presentations

arctic sea ice in trasnformation: a review of recent observed …. (2014)
sea ice → ice that grwos and melts within ocean water (meiers et al. 2014)
maximum extnet in late february, minimum in september (in the northern hemisphere)
two plankton blooms in the future? due to vertical mixing
loss of habitat:
- contraction of arctic species, introduction
- compettion for food; changes in copepod comuniteis
- zooplankton depend on lipid rich ice algae
- rapid changes in sea ice cover increases vulnerability for ice dependent high trophic level organisms

northeast atlantic cod
ocean acidification
- dissolution of anthropogenic carbon dioxide in marine water
studying cod larvae and OA
- stiansy et al. (2016)
OA and increasing temperatures
- Hänsel et al. (2020)
- combined effects of fishing, warming, and acidification
OA and increasing temperature
- Hansen et al. (2024)
Different models give different results

rogers et al. (2011)
according to NIVA’s report, the major pressures are:
- overfishing, habitat loss, pollution and rising temperatures
coastal cod more vulnerable to local wamring (they stay in that area)
long time series of 91 years
linked body size to spring (feb-april) and summer (july-sep) sea temperature
long term trend of declining body size
spring warming gave larger cod, however, warmer summers gave smaller cod
high population density → smaller fish
temperature is a major driver of cod body size and survival
smaller juveniles → lower survival and reproduction
interacting stressors: warming + competition + pollution

animal welfare aspect: they die from suffocation or asphyxiation or drowning
smallest toothed whales
short life span of 12 years
feed on energy rich fish
lives close to the coast, vulnerable to human fishery activities
29000 individuals killed by bycatch every year
by catch in gill net fisheries
- become entangled, therefore death by suffocation
- play an importnat role in the coastal ecosystem
- norway has unsustainable bycatch numbers
reduce bycathc with pingers
- small acoustic alarms that can be attached to the net
- emit sounds and warnings that is at frequencies where the porpoises can hear the sound
monitoring bycatch of harbour porpoise
- most bycatch in vestfjorden
pingers can prevent bycatch in Norway

Bjørge et al. (2017)
lat 90s to 2014 - 555 harbour seals and 466 grey seals
significant drop in pup production between 2007 and 2014
south trøndelag and north trøndelag, had a 65% decrease in population
peaks of bycatch is july- december
bycatch north of 62 degrees appears to be increasing, likely due to large mesh gillnets
animal welfare aspect: they die from suffocation or asphyxiation or drowning

Grattagliano et al. (20—-)
plastic → collection of polymers; primary or secondary with different characteristics
microplastics → less than 5 mm in size
distribution and fate:
- mainly found in surface water, water column, sediments, deep sea, and atmosphere
- trasnport influenced by denisty, size, currents, biofouling, and aggregation
- biofouling → particles sink or float differently
- degredation is very slow; they persists for decades
ecological impacts:
- ingestion documented in plankton, fish seabirds, and mammals
- effect: reduced feeding, growth inhibition, oxidative stress, inflammation
- trophic transfer through food web
- may act as a vector for pathogens
key groups effected:
- phytoplankton
- zooplankton
- invertebrates (bivalves, crustaceans, echinoderms)
- fish
- commercial

EAFM (ecosystem approach to fisheries management)
- an objective adopted by many governments and International organisations since the 1990s
aim is to switch from single species to multi species model
how is it implemented?
- bycatch mitigation
- multi species management and prey predator relationships
- protection of vulnerable marine ecosystems
- integrated ecosystem approach