Salinity ranges

Métodos Operacionais
em Biologia Marinha
Rui Rosa
Faculty of Sciences,
University of Lisbon, Portugal
MOBM
Introdução dos métodos de
amostragem mais utilizados
em estudos de Biologia
Marinha
Jumbo squids in Baja of California, 2007
The Ocean as Habitat:
Physical Characteristics of Earth’s Oceans
~71% of the earth’s surface are
oceans
Maximum depth: ca. 11,022 m
(Land: Mt Everest 8,848 m)
Average depth: ca. 3800 m
Total volume: 1370 x 106 km3
Presents 300 times more space for
life than land and freshwater
combined.
The Ocean as Habitat:
Physical Characteristics of Earth’s Oceans
All known phyla originated in the
sea, and life on earth is believed to
have begun in the ancient oceans
Only 2% of human food originates
from the oceans but present 20% of
high quality protein nutrition
Still recent NASA scientist said: “We
now know more about the backside
of the moon than about the depths
of our oceans.”
Marine vs. Terrestrial Life
Marine
Terrestrial
•Organisms – similar density as environment
(salt water) less energy to float/swim… small
effect of gravity
•Organisms – much higher density than air
… than to walk or fly.
High gravity impact (fall down)
. Water supports bodies, no need to put
energy in skeletons
•Need strong skeletal material (animals:
bones; trees: trunks)
•Plenty of water for life
•May become water limited
•Temperature variation low
•Temperature varies strongly
•Light limited (reflection of light at sea surface
and rapid light absorption with water depth)
•Light energy substantially higher than in
aquatic systems, low absorption by air
•Nutrient limited: nitrate, phosphate, silicate,
iron
•High nutrient concentrations in natural soils
•Major part of nutrient regeneration in the
dark deep-sea
•Nutrient regeneration in soil close to plant
uptake
•Physically unstable habitats
•Physically stable environment
Water
So what?
Water
Chemical properties of seawater
Six ions account for 99% of dissolved components
in seawater:
chloride (Cl-), 55.4%
sodium (Na+), 30.61%
sulfate (SO42-), 7.68%
magnesium (Mg2+), 3.69%
calcium (Ca2+), 1.16%
potassium (K+), 1.10%
Trace ions: several trace elements can be limiting,
and called micronutrients (e.g. Fe and Si).
Where do the salts come from?
Origin (ancient): Water vapor in Earth’s early atmosphere reacted with volcanic
gases and dust; most important gases (chlorine, sulfur dioxide, carbon dioxide)
– formed acids (HCl, H2SO3, H2CO3) in rain water, which dissolved minerals
from rocks
Where do the salts come from?
Similar processes occur today, but slower (less volcanic activity)
Weathering: interaction water – rocks, dissolves new minerals & loss by
precipitation
Water / sediment interaction
at seafloor – gain of dissolved
material (e.g. reactions with
volcanic rocks and
sediments).
Salinity
Original definition: Salinity = total salts (ions) in
water; [‰]
35‰ = 35 g ions / kg water = 3.5%
Modern definition: Salinity = ratio of conductivities
of sea water and standard solution of KCl
(standard water)
Modern unit: “practical salinity scale” (S=33.4
psu); in biological literature still ‰ erlaubt
Salinity
Salinity ranges:
Open ocean: 32 – 38; avg. 35
Coastal ocean: 27 – 30
Estuaries: 0 – 30 [brackish]
Semi-enclosed seas (Baltic Sea): <25
[brackish]
Hypersaline environments (Red Sea,
tropical coastal lagoons, tide ponds in
warm climate): >40
Salinities between 0.1 and 30: brackish
water
Salinity variation much higher in surface
waters than in deep-sea (lack of sea-air
interaction)
Salinity
Salinity ranges:
Open ocean: 32 – 38; avg. 35
Coastal ocean: 27 – 30
Estuaries: 0 – 30 [brackish]
Semi-enclosed seas (Baltic Sea): <25
[brackish]
Hypersaline environments (Red Sea,
tropical coastal lagoons, tide ponds in
warm climate): >40
Salinities between 0.1 and 30: brackish
water
Salinity variation much higher in surface
waters than in deep-sea (lack of sea-air
interaction)
Salinity
Precipitation/Evaporation balance
influence surface salinity
Precipitation is highest in north of
equator and temperate regions
Evaporation is highest in
subtropics
E – P mirrors latitudinal
distribution of salinity
Salinity
Species that tolerate wide range
of salinities = euryhaline;
species with narrow salinity
tolerance = stenohaline
Temperature
. Controls rates of
chemical reactions
Controls rates of
biological processes
(Q10: ratio of metabolic
processes at 10°C
difference; mostly close
to 2)
Temperature
. with salinity determine water
density (which controls vertical
water movement, currents,
stability/mixing)
. determines concentration of
dissolved gases in water (< gas
solubility > temperature)
Temperature
sets limits to species’ distribution:
eurytherm: wide temp. range
stenotherm: narrow temp. range
poikilotherm: body temperature = water temperature
Temperature
Temperature-depth profile
280 – 320 nm: UV-B (harmful)
320 – 400 nm: UV-A
400 – 700 nm: PAR – Photosynthetically Active Radiation
> 700 nm: IR (Infrared Radiation)
Light decreases
exponentially with depth
Blue light penetrates
deepest into the ocean,
Red light is absorbed
fastest (“live seems more
‘colorless’ with depth”)
Coastal oceans: stronger
light absorption, brownish
to greenish due to shift in
spectral absorbance
Open oceans: clearest
water, deep euphotic
zone, blue color
Light decreases
exponentially with depth
Blue light penetrates
deepest into the ocean,
Red light is absorbed
fastest (“live seems more
‘colorless’ with depth”)
Coastal oceans: stronger
light absorption, brownish
to greenish due to shift in
spectral absorbance
Open oceans: clearest
water, deep euphotic
zone, blue color
Day and Night Depth
Distribution of
Jumbo squid as indicated by
acoustic tagging
Horizontal distribution of zooplankton
•Light penetrates only down to 100-200 m
depth
•Herbivores, which feed on phytoplankton,
are restricted to the euphotic zone
•Carnivores, which feed on zooplankton,
thrive in mid-waters
•Omnivores, which eat both living prey and
dead material (fecal pellets, dead organisms)
thrive in the deep-sea
Classification of the Marine Environment
Classification by light
Photic and aphotic
Phytoplankton need
light to
photosynthesize and
can only thrive in the
photic zone
Zooplankton (animals)
and bacteria do not
need light and inhabit
the oceans down to the
deep-sea floor
Classification of the Marine Environment
Classification by location
. Water and sea floor
divided into specific zones:
benthic & pelagic
. By water depth divided
into coastal/neritic, oceanic
. Each has distinct physical
and chemical
characteristics
. Each supports different
organisms
Tides
• Gravitational forces of sun and
moon add at full and new moon
to produce spring tides.
• Gravitational forces of sun and
moon compete at half moon to
produce neap tides.
Tides
. Lunar tides occur twice a day
(semidiurnal tides),
. Solar tides once a day
(diurnal tides)
. Depending on the orbital
position of sun and moon and
ocean region, mixed tides
occur.
Tides are amphidromic waves
Amphidromic motion - Tides revolve around a single point where the water level does not
change known as the amphidromic point