Coastal interfaces Flashcards
What are main environmental gradient factors in rocky interfaces?
Tide height and hydrodynamism, emersion period, temperature, salinity, oxygen and food availability
What is meant by zonation?
Clear layer distinction
Each layer is dominated by certain organisms
3 zones are visible
What are the three zones of rocky interfaces?
Supralitoral, eulitoral, infralitoral
What characterizes the supralitoral?
Wave action
Presence of lichens and litorinides
What characterizes eulitoral?
In the tidal range
Barnacles and mussels
What characterizes infralitoral?
Starts where low tide is
Presence of seaweed and kelps
What characterizes environmental gradient of sandy interfaces?
Tide height and hydrodynamism, particles’ dimension
Is zonation present in sandy interfaces?
No
What organisms live in sandy interfaces?
Endobenthic small organisms, polychaetes, bivalves, and several larger crustaceans.
What are the two kinds of beaches?
Reflective and dissipative
What characterizes reflective beaches?
Narrow and steep profile, reflect waves and have larger grain size
The biological community is less diverse and abundant
Describe dissipative beaches
Large, flat and shallow profile, fine sediments and larger wave profile
Rich biological community, particularly subtidal zone
What are estuaries?
Transition zones where the river meets the sea
Describe geological formation of estuaries
1) During ice ages covered in ice or empty due to much lower sea level
2) Inundation of valleys after ice thawing
3) Dynamic systems, rich in sediments
Until what height is an estuary considered such?
Up to sea elevation inside river valley
Into what parts is an estuary divided?
1) Marine/ Inferior, connected to the sea
2) Medium, mixed seawater and fresh water
3) Fluvial/Superior, mostly freshwater and influenced by diurnal tide action
Is an estuary always open to the sea?
Not necessarily, it can be periodically closed off, depending on the inflow of river water, which influences salinity
What is an estuary divided into based on water mixing?
Tidal river
Mixing zone
Turbid coastal zone
Describe tidal river zone
Absence of salinity fluctuations but with changes in water level
Describe mixing zone
Mix of water masses and strong physical, chemical and biological gradients
Extends until opening in the sea
Describe turbid coastal zone
Located in open ocean
What is the order of estuary type following rising sea level?
1) Fjord, narrow and U profile
2) V profile
3) Funnel shaped estuary
Describe fjords
elevated glacial sediments barrier limits sea water intrusion
Low oxygen and organisms in depth
Describe V profiles
Divided into channels and less deep than funnel estuaries
What is delta?
Low-lying plain, formed by accumulation of alluvium (fluvial sediments)
How does a tectonic estuary form?
Sink of land as result of faults moving
How is tidal range divided?
Microtidal <2m
Mesotidal 2-4m
Macrotidal >4m
How are estuaries classified based on horizontal salinity gradient?
Positive, inverse (salinity of river is higher than sea due to evaporation) or neutral
How are estuaries classified based on vertical salinity profile?
1) Well mixed, same salinity in the whole profile
2) Highly stratified (with salt wedge), much higher salinity in the bottom
3) Partially stratified (less significant salt wedge), limited mixing zone between sea and fresh water
How does salinity vary spatially and temporally?
Spatially in longitude and vertically
Temporally with diurnal or semi-diurnal tide, also seasonally
How is sediment ditributed in the estuary?
Large sediment is deposited where flow velocity of river and tide is higher (gravel or shells, than sand)
At lower velocity, where river and tide meet, silt is deposited
What causes flocculation in estuary?
Negatively charged clay particles are balanced by positive ions from seawater, and are not repelled but can stick together, causing flocculation and turbidity
Where is maximum turbidity?
at null point: point on the bottom of the water where the sum of sea and river current is zero. Moves with tides
What are three types of deltas?
River - elongated
Tide - fan-shaped and channels perpendicular to coast
Wave - waves push sediments and delta is defined and parallel to shore
How is species diversity in estuaries?
Low, as compared to high productivity
Define ecotone
Area of rapid alteration in between two homogeneous ecological communities (seawater and freshwater). Usually dynamic and unstable
Define ecocline
Gradual frontier of change between two systems
It is a gradient zone, containing heterogeneous communities, more stable than ecotones
Define double ecocline
Zone with species that occurr in both saline and fresh zone of the estuary
What is physiological plasticity?
Metabolic cost of living in variable natural habitat
What are euryhaline organisms?
Can tolerate high range of salinity, most species in the estuary
What are stenohaline organisms?
Species that tolerate small range of salinity, therefore live in the extremities of estuary, in marine or river water
How are species divided based on osmolarity?
Osmoconformes - vary osmolarity according to external osmolarity
Limited osmoregulators - limited ability to osmoregulate
Osmoregulators - do not vary their internal osmolarity, independent of external
What is osmolarity?
Numer of dissolved particles in a solution
Estuarine species
Live in estuaries, highly euryhaline
Marine migrants
Spawn at sea but use estuaries as nurseries, they are highly euryhaline
Marine stragglers/occasionals
Marine species that occasionally enter the estuary, mostly live in coastal interface
Usually stenohaline
Anadromous species
Live in the sea but cross the estuary to reach freshwater, where they reproduce
Catadromous species
Live in freshwaters, but cross the estuary to reach the sea, where they reproduce
Freshwater species
Live in freshwater and stenohaline
What are salt/tidal marshes?
habitats with vegetation tolerant to high salinity
In the zone between tides of estuarine and marine systems. They are sheltered from tidal currents and wave action, and characterized by fine sediments and organic matter
What are vegetation rhizomes?
Laterally extended vegatation that has roots in underwater soil, but extend outside of water. Usually spread asexually. Rhizome system slows water movement and favours sedimentation
Why is zonation present in salt marshes?
Because of different tide height, salinity tolerance and competition between species moving from the sea
What does halophyte mean?
Tolerant to salt water
What are mangrove forests?
Habitats of halophyte vegetation of larger size, occurring in tropical zones
Is zonation present in mangrove habitats?
yes
What are seagrasses?
Habitats of halophyte coastal vegetation, the only one capable of producing flowers in submerged conditions. Low hydrodynamics and high sedimentation
What are some coastal system ecoservices?
Regulation, provision and culture
What is blue carbon?
Carbon uptaken by marine ecosystems and plants
What are kelp forests?
Forests of brown algae, found in temperate rocky coastal areas rich in nutrients
