1. Cryosphere
Marine ice-related definitions were taken from WMO Sea Ice Nomenclature
(2014). WMO classifies ice into two major categories; sea and glacier
ice.
Sea ice grows and melts within ocean waters. First-year ice (FYI)
develops from young ice, is of not more than one winter’s growth, and
has an average thickness of 0.3-2 m. Multi-year ice (MYI) is old ice
that has survived at least two summers’ melt and can be >3m
thick.
Ice shelves are floating platforms of ice that can reach up to 1500 m
thickness. They are formed when ice sheets (continental ice) or glaciers
meet the sea (Ingels et al. 2018).
Glacier ice is ice in or originating from a glacier, whether on land or
floating at the sea surface as icebergs.
Icebergs are massive forms of floating ice greatly varying in shape,
protruding >5m above sea level. The largest category is
tabular berg, which forms by calving from an ice shelf (mega icebergs,
Fig.1) while small icebergs can extend 5-15 above sea level, and be
15-60 m in length.
2. Polar biocenosis
Sympagic communities are those living in association with the sea ice
microhabitats and include algae, bacteria, fungi, heterotrophic
protozoans, and metazoans such as nematodes, rotifers and copepods.
Ice-obligate species are those that require sea ice for either breeding,
hunting or rearing offspring. e.g. polar bear, walrus, Adélie penguin.
Cryophilic species are those restricted to the polar biome
Cryotolerant species are those with broad environmental preferences
including, but not limited to, the polar biome (adapted from Bringloe et
al. 2022).
Vulnerable marine ecosystems (VMEs) are hotspots of biodiversity and
ecosystem functioning in the deep sea (Ashford et al. 2019). They have
low recovery potential and are highly vulnerable to disturbances. VMEs
designation is a critical management framework to prevent significant
adverse impacts due to fishing activity. e.g., cold-water coral reefs,
and deep-sea sponge aggregations, cup coral fields.
3. Ecosystem Services (ES)
ES can be divided into Regulating (climate regulation, biological
control), Habitat/Supporting (life cycle maintenance, gene pool
protection, nutrient cycling), Provisioning (food, medicinal and genetic
resources, raw materials), and Cultural (heritage, recreation,
spiritual) (Steiner et al. 2021)
Blue Carbon is the carbon biologically captured and stored in marine
ecosystems (Nellemann et al. 2009) including coastal, open ocean, and
deep-sea ecosystems. Blue carbon offers potential as a Nature-based
Solution (NbS) to climate change, hence complies with the climate
regulation ES (Christianson et al. 2022).
Carbon capture (hours to months) primary producers (planktic and
benthic) use dissolved inorganic CO2 and transform it
into biomass (organic carbon, OC).
Carbon immobilisation (years to centuries) benthic calcifiers absorb
dissolved inorganic carbon (DIC) to form shells and skeletons. Hard
skeletal matrices are less prone to microbial action, thus have longer
times of permanence.
Carbon sequestration (centuries to millennia) carbon buried in anoxic
sediments is out of the carbon cycle over geological times (Bax et al.
2021).
4. Other
Tipping points or critical threshold is a point at which a small
perturbation can cause a considerable change in future states of a
system. The timescale at which this occurs is set by internal dynamics
of the system (Lenton and Williams 2013).
|