marine environment

1. Marine EnvironmentMarine Environment
Dr. P. Sureshkumar M.Sc., M.Phil., M.B.A.,
Ph.D.,
Assistant Professor in Environmental
Sciences
CAS in Marine Biology

2. Marine EnvironmentMarine Environment
ByBy
Dr. P. SureshkumarDr. P. Sureshkumar M.Sc., M.Phil., M.B.A., Ph.D.,M.Sc., M.Phil., M.B.A., Ph.D.,
Assistant Professor in Environmental SciencesAssistant Professor in Environmental Sciences
CAS in Marine BiologyCAS in Marine Biology
Annamalai UniversityAnnamalai University

3. INTRODUCTIONINTRODUCTION
 About 71% of the earth surface is covered byAbout 71% of the earth surface is covered by salt watersalt water
 The water depth averages 3.8km, a volume of 1370 x 106 km3The water depth averages 3.8km, a volume of 1370 x 106 km3
 They provide us food, energy and water and sustain theThey provide us food, energy and water and sustain the
livelihoods of hundreds of millions of peoplelivelihoods of hundreds of millions of people
 They are the stabilizer of the world’s climateThey are the stabilizer of the world’s climate
 In marine environment about 178,000 species in 34 phylaIn marine environment about 178,000 species in 34 phyla
(UNEP) are present(UNEP) are present

4. OceanOcean
 The oceans are originally the great mass of salt water,The oceans are originally the great mass of salt water,
supported to encompass the disk of the earth.supported to encompass the disk of the earth.
 They are considered to be ancient formations in theThey are considered to be ancient formations in the
morphology of the earth and are mainly separatedmorphology of the earth and are mainly separated
from each other by the continents.from each other by the continents.

5. The OceansThe Oceans
1.1. The ocean is divided into 5 oceans (Southern Ocean was added inThe ocean is divided into 5 oceans (Southern Ocean was added in
2000)2000)
2. Pacific ocean is the largest; more than ½ of Earth’s water & covers2. Pacific ocean is the largest; more than ½ of Earth’s water & covers
⅓ of Earth’s surface⅓ of Earth’s surface
3. Oceans have changed over time due to plate tectonics3. Oceans have changed over time due to plate tectonics

6.  The ocean is divided into large five areas,The ocean is divided into large five areas,
 1. Antarctic ocean1. Antarctic ocean
 2. Arctic ocean2. Arctic ocean
 3. Atlantic ocean3. Atlantic ocean
 4. Indian ocean and4. Indian ocean and
 5. Pacific ocean5. Pacific ocean

7. SeaSea
 The seas are varying extents separated fromThe seas are varying extents separated from
the oceans bythe oceans by island chainsisland chains or byor by submarinesubmarine
ridgesridges rising from the sea floor, subjected torising from the sea floor, subjected to
considerable changes in the course ofconsiderable changes in the course of
geological historygeological history
 Example:Example: North sea, Mediterranean sea, Red sea,North sea, Mediterranean sea, Red sea,
Black sea, Arabian sea,Caribbean sea, Baltic seaBlack sea, Arabian sea,Caribbean sea, Baltic sea etc.etc.

8.  It is due to their acute partition from the oceans,It is due to their acute partition from the oceans,
the seas have definite unique characteristics,the seas have definite unique characteristics,
which are closely connected with the reducedwhich are closely connected with the reduced
exchange of water masses, they showexchange of water masses, they show
considerable divergence between each other,considerable divergence between each other,
because their water masses react morebecause their water masses react more
noticeably than the open oceans to the localnoticeably than the open oceans to the local
climatic situation.climatic situation.

9. Marine Life ZonesMarine Life Zones
factors that divide the ocean into marine life zonesfactors that divide the ocean into marine life zones
 sunlightsunlight
 distance from shoredistance from shore
 water depthwater depth

10. Division of the MarineDivision of the Marine
EnvironmentEnvironment
 The marine ecosystem is the largest aquatic systemThe marine ecosystem is the largest aquatic system
on the planet.on the planet.
 Its size and complexity make it difficult to deal withIts size and complexity make it difficult to deal with
as a whole.as a whole.
 As a result, it is convenient to divide it into moreAs a result, it is convenient to divide it into more
manageable arbitrary subdivisions.manageable arbitrary subdivisions.
 Open ocean can be subdivided vertically andOpen ocean can be subdivided vertically and
horizontally (Hedgepeth, 1957).horizontally (Hedgepeth, 1957).

11.  The ocean can be divided into zonesThe ocean can be divided into zones
based onbased on depthdepth (vertically) and(vertically) and distancedistance
from landfrom land (horizontally)(horizontally)
 Different zones of the ocean haveDifferent zones of the ocean have
conditions that support different organismsconditions that support different organisms

12.  The entire area of the open water is the pelagicThe entire area of the open water is the pelagic
realm OR Pelagic Zonerealm OR Pelagic Zone
 Sea bottom is benthic realm or Benthic ZoneSea bottom is benthic realm or Benthic Zone

13.  Horizontally, the pelagic realm can be dividedHorizontally, the pelagic realm can be divided
into two zones.into two zones.
 The neritic zone encompasses the water mass thatThe neritic zone encompasses the water mass that
overlies the continental shelvesoverlies the continental shelves
 The oceanic zone includes all other open watersThe oceanic zone includes all other open waters

14.  Progressing vertically, the pelagic realm canProgressing vertically, the pelagic realm can
be further subdivided in to two based on lightbe further subdivided in to two based on light
penetrationpenetration
 The photic or euphotic zone is that part of the pelagicThe photic or euphotic zone is that part of the pelagic
realm that is lightedrealm that is lighted
 The permanently dark water mass below the photicThe permanently dark water mass below the photic
zone is the aphotic zonezone is the aphotic zone

15.  Some scientists prefer to recognize a transition zoneSome scientists prefer to recognize a transition zone
between the photic and aphotic called the disphoticbetween the photic and aphotic called the disphotic
zonezone
 This transition area has enough light for vision butThis transition area has enough light for vision but
not enough for photosynthesis and extends down tonot enough for photosynthesis and extends down to
about 1000mabout 1000m
 Disphotic is synonymous here with mesopelagicDisphotic is synonymous here with mesopelagic

16.  The pelagic part of the aphotic zone can be subdivided intoThe pelagic part of the aphotic zone can be subdivided into
zones that succeed each other vertically.zones that succeed each other vertically.
 The mesopelagic is the uppermost of the aphotic areas. ItsThe mesopelagic is the uppermost of the aphotic areas. Its
lower boundary in the tropics is the 10ºC isotherm, whichlower boundary in the tropics is the 10ºC isotherm, which
ranges from 700 to 1000m, depending on the area.ranges from 700 to 1000m, depending on the area.
 Next is the bathypelagic, lying between 10 and 4 ºC or inNext is the bathypelagic, lying between 10 and 4 ºC or in
depth between 700 and 1000m and between 2000 and 4000m.depth between 700 and 1000m and between 2000 and 4000m.
 Overlying the plains of the major ocean basins is the abyssalOverlying the plains of the major ocean basins is the abyssal
pelagic, which has its lower boundary at about 6000m.pelagic, which has its lower boundary at about 6000m.
 The open water of the deep oceanic trenches between 6000The open water of the deep oceanic trenches between 6000
and 10,000m is called the hadal pelagic.and 10,000m is called the hadal pelagic.

17.  Corresponding to the last three pelagic zones areCorresponding to the last three pelagic zones are
three bottom or benthic zones.three bottom or benthic zones.
 The bathyal zone is that area of bottomThe bathyal zone is that area of bottom
encompassing the continental slope and down toencompassing the continental slope and down to
about 4000m.about 4000m.
 The abyssal zone includes the broad abyssal plains ofThe abyssal zone includes the broad abyssal plains of
the ocean basins between 4000 and 6000m.the ocean basins between 4000 and 6000m.

18.  The hadal is the benthic zone of the trenches betweenThe hadal is the benthic zone of the trenches between
6000 and 10,000m.6000 and 10,000m.
 The benthic zone underlying the neritic pelagic zoneThe benthic zone underlying the neritic pelagic zone
on the continental shelf is termed the sublittoral oron the continental shelf is termed the sublittoral or
shelf zone.shelf zone.
 It is illuminated and is generally populated with anIt is illuminated and is generally populated with an
abundance of organisms constituting several differentabundance of organisms constituting several different
communities, including seagrass beds, kelp forestscommunities, including seagrass beds, kelp forests
and coral reefs.and coral reefs.

20. Pelagic and benthic zone divisionsPelagic and benthic zone divisions
2020
Pelagic zone divisions
(depth from surface)
Benthic zone divisions
(seafloor zones)
Supralittoral –shore above high tide
Epipelagic (0-200m) Littoral – the intertidal zone (sometimes
submerged and sometimes above water)
Mesopelagic (200-1,000m) Sublittoral – seafloor of the continental
shelf (from low tide to the shelf break)
Bathypelagic (1,000-4,000m) Bathyl – seafloor of the continental slope
to the deep ocean bottom
Abyssopelagic (4,000-6,000m Abyssal – deep ocean bottom between
the base of the slope and 6,000 m
Hadalpelagic (6,000-10,000m) Hadal – the deepest zone, below 6,000m

21. Fig.1. Divisions of the oceans (not to scale) (Source: Hedgpeth, 1957)Fig.1. Divisions of the oceans (not to scale) (Source: Hedgpeth, 1957)

25. Coastal ZoneCoastal Zone
 Two traditional areas exist, one between the marineTwo traditional areas exist, one between the marine
environment and the terrestrial, and the other betweenenvironment and the terrestrial, and the other between
marine and fresh water.marine and fresh water.
 The intertidal zone or littoral zone is that shore areasThe intertidal zone or littoral zone is that shore areas
lying between the extremes of high and low tide; itlying between the extremes of high and low tide; it
represents the transitional area from marine torepresents the transitional area from marine to
terrestrial conditions.terrestrial conditions.
 It is a zone of abundant life and is well studied.It is a zone of abundant life and is well studied.
 Estuaries represent the transition area where fresh andEstuaries represent the transition area where fresh and
salt water meet and mix.salt water meet and mix.
 These are important breeding and feeding grounds forThese are important breeding and feeding grounds for
sea birds, shore birds and waterfowl.sea birds, shore birds and waterfowl.

26. Exclusive Economic Zone (EEZ)Exclusive Economic Zone (EEZ)
 The earliest use of the oceans by humans was probablyThe earliest use of the oceans by humans was probably
for food.for food.
 Early human populations living along the oceansEarly human populations living along the oceans
captured various shore fishes and shellfishes forcaptured various shore fishes and shellfishes for
consumption with the advent of vessels and nets.consumption with the advent of vessels and nets.
 In the decades of this century, the old ships and gearIn the decades of this century, the old ships and gear
have been replaced by much larger and more powerfulhave been replaced by much larger and more powerful
vessels, more effective nets and traps and electronicvessels, more effective nets and traps and electronic
devices for detecting fish schools.devices for detecting fish schools.

27.  The result has been a significant reduction inThe result has been a significant reduction in
many fish populations and the disappearancemany fish populations and the disappearance
or over exploitation of others at a time whenor over exploitation of others at a time when
increasing human populations are demandingincreasing human populations are demanding
more food.more food.
 The decline of many world fisheries due toThe decline of many world fisheries due to
common access and the pressures of ancommon access and the pressures of an
increased demand for food by an ever‐increased demand for food by an ever‐
increasing human population have led toincreasing human population have led to
friction among fishing nations and variousfriction among fishing nations and various
attempts to regulate fishery resources.attempts to regulate fishery resources.

28.  Following the third United Nations Conference on theFollowing the third United Nations Conference on the
Law of the Sea, a standard 200 nautical miles wideLaw of the Sea, a standard 200 nautical miles wide
fishing areas from the ‘base lines’ called economic zonefishing areas from the ‘base lines’ called economic zone
(EEZ) was established for the waters of each coastal(EEZ) was established for the waters of each coastal
nations.nations.
 This means that individual nations now have full controlThis means that individual nations now have full control
of all fishery activity within 200 miles of their shores andof all fishery activity within 200 miles of their shores and
they have sovereign rights over the resources of theirthey have sovereign rights over the resources of their
continental shelves that, in some cases, can extendcontinental shelves that, in some cases, can extend
even further.even further.

29. Continental areaContinental area
 Supports abundant benthic fauna and flora – the shelfSupports abundant benthic fauna and flora – the shelf
communities.communities.
 The water above the continental shelves and its fauna and floraThe water above the continental shelves and its fauna and flora
are described as neritic.are described as neritic.
 Neritic waters tend to be richer in plant nutrients and moreNeritic waters tend to be richer in plant nutrients and more
productive than water of corresponding depths in the open sea.productive than water of corresponding depths in the open sea.
 One reason for this is the greater mixing that occurs here as aOne reason for this is the greater mixing that occurs here as a
result of turbulence, wave action, upwelling caused byresult of turbulence, wave action, upwelling caused by
offshore currents, winds etc., bringing plant nutrients into alloffshore currents, winds etc., bringing plant nutrients into all
strata of the water.strata of the water.

30.  Also, additional nutrients are led from the substrateAlso, additional nutrients are led from the substrate
and washed into the sea by rivers and streams fromand washed into the sea by rivers and streams from
the adjacent land.the adjacent land.
 Where the substrate is suitable for attachment, theWhere the substrate is suitable for attachment, the
shallow waters also support a rich growth of seaweed,shallow waters also support a rich growth of seaweed,
turtle grass, eelgrass and in some areas, other plants.turtle grass, eelgrass and in some areas, other plants.
 The increased plant growth is reflected in an increaseThe increased plant growth is reflected in an increase
in animal life.in animal life.

31. Coral ReefsCoral Reefs
 Coral reefs are shallow water tropical marine ecosystems‐Coral reefs are shallow water tropical marine ecosystems‐
characterized by a remarkably high biomass production and acharacterized by a remarkably high biomass production and a
rich floral and faunal diversities.rich floral and faunal diversities.
 Reef is formed by the millions of calcareous skeleton of coralsReef is formed by the millions of calcareous skeleton of corals
(marine invertebrate of the phylum Coelenterata) cemented(marine invertebrate of the phylum Coelenterata) cemented
together over a period of few thousand to millions of years.together over a period of few thousand to millions of years.
 Coral reefs are of three types i.e. Fringing reefs (projectCoral reefs are of three types i.e. Fringing reefs (project
seawards directly from the shore), Barrier reefs (separatedseawards directly from the shore), Barrier reefs (separated
from the land mass by a shallow lagoon) and Atolls (rest onfrom the land mass by a shallow lagoon) and Atolls (rest on
the summits of submerged volcanoes).the summits of submerged volcanoes).
 An abundance of pelagic fish resources is found in the reefs,An abundance of pelagic fish resources is found in the reefs,
including food fishes as well as a variety of beautiful aquariumincluding food fishes as well as a variety of beautiful aquarium
fishes such as parrot, porcupine,rainbow and surgeon.fishes such as parrot, porcupine,rainbow and surgeon.

32. MangrovesMangroves
 Mangroves are tropical and subtropical swampy forestsMangroves are tropical and subtropical swampy forests
bordering the sheltered seacoasts and estuaries.bordering the sheltered seacoasts and estuaries.
 Mangroves are highly complex and dynamic ecosystemsMangroves are highly complex and dynamic ecosystems
comprising salt tolerant intertidal halophytes and the adjoiningcomprising salt tolerant intertidal halophytes and the adjoining
waterways, supporting numerous terrestrial, arboreal, benthicwaterways, supporting numerous terrestrial, arboreal, benthic
and aquatic organisms forming a complex association ofand aquatic organisms forming a complex association of
species, exchanging materials and energy with the system,species, exchanging materials and energy with the system,
between the system and near coastal waters.between the system and near coastal waters.
 Mangroves are unique in possessing special adaptiveMangroves are unique in possessing special adaptive
structures to live in the saline coastal environments.structures to live in the saline coastal environments.

33.  They include specialized root cell membranes which prevent‐They include specialized root cell membranes which prevent‐
or reduce the entry of salt; elaborate tube like breathing‐or reduce the entry of salt; elaborate tube like breathing‐
structure called pneumatophores which grow verticallystructure called pneumatophores which grow vertically
upwards from the roots; and viviparous seedlings thatupwards from the roots; and viviparous seedlings that
germinate on the parent tree itself thereby decreasing theirgerminate on the parent tree itself thereby decreasing their
mortality in the unfavourable environment.mortality in the unfavourable environment.
 Mangroves serve a wide variety of useful functions includingMangroves serve a wide variety of useful functions including
prevention of coastal erosion, encouraging soil deposition,prevention of coastal erosion, encouraging soil deposition,
providing food, shelter and serve as a sanctuary of birds andproviding food, shelter and serve as a sanctuary of birds and
mammals.mammals.
 They provide vital spawning, nursery and forage ground for aThey provide vital spawning, nursery and forage ground for a
wide variety of aquatic organisms and as organic food factorywide variety of aquatic organisms and as organic food factory
through litter production.through litter production.

34. WetlandsWetlands
 Wetlands are diverse in both form and function.Wetlands are diverse in both form and function.
 They encompass the salt marshes and mangrove swamps ofThey encompass the salt marshes and mangrove swamps of
seacoast and estuary, the freshwater marshes of the prairie, theseacoast and estuary, the freshwater marshes of the prairie, the
flood plain swamps of rivers, and the littoral zone marshes of‐flood plain swamps of rivers, and the littoral zone marshes of‐
lakes.lakes.
 Wetland is an ecotone, the transitional zone between land andWetland is an ecotone, the transitional zone between land and
water, and it combines the characteristics of both thesewater, and it combines the characteristics of both these
environs besides having some unique characteristics of itsenvirons besides having some unique characteristics of its
own.own.
 The heterogeneous wetland habitat broken into diverseThe heterogeneous wetland habitat broken into diverse
microhabitat consists of permanent or seasonal shallow watermicrohabitat consists of permanent or seasonal shallow water
bodies dominated by large aquatic plants.bodies dominated by large aquatic plants.

35.  Wetlands are divided into four groups based on the dominantWetlands are divided into four groups based on the dominant
large vegetation, the source of water and presence or absence oflarge vegetation, the source of water and presence or absence of
peat.peat.
 1. Marshes are characterized by emergent aquatic macrophytes.1. Marshes are characterized by emergent aquatic macrophytes.
 2. Swamps are dominated by trees.2. Swamps are dominated by trees.
 3. Acidic bogs are characterized in having low species diversity3. Acidic bogs are characterized in having low species diversity
with a few higher plants and an abundance of the peat mosswith a few higher plants and an abundance of the peat moss
Sphagnum.Sphagnum.
 4. The more alkaline4. The more alkaline ferns are often species that contain bothferns are often species that contain both
mosses and aquatic macrophytes.mosses and aquatic macrophytes.

36.  The main wetland types differ in their rates of primaryThe main wetland types differ in their rates of primary
production in the following order Marshes > swamps > ferns >production in the following order Marshes > swamps > ferns >
bogs.bogs.
 To day, the preservation of wetlands is considered importantTo day, the preservation of wetlands is considered important
by both scientists and the public.by both scientists and the public.
 Therefore, considerable thought has gone into distinguishingTherefore, considerable thought has gone into distinguishing
wetlands from other aquatic and terrestrial habitats.wetlands from other aquatic and terrestrial habitats.
 The characteristics of shallow water, saturated soil andThe characteristics of shallow water, saturated soil and
dominance by vegetation adapted to water logged conditionsdominance by vegetation adapted to water logged conditions
define wetlands.define wetlands.

37.  The scientific study of wetlands is difficult and much remainsThe scientific study of wetlands is difficult and much remains
to be discovered.to be discovered.
 One reason is that wetlands are the most physically andOne reason is that wetlands are the most physically and
chemically heterogeneous of all the major aquatic ecosystems.chemically heterogeneous of all the major aquatic ecosystems.
 Wetlands are of considerable economic importance. They canWetlands are of considerable economic importance. They can
be highly productive with large crops, of algae, macrophytes,be highly productive with large crops, of algae, macrophytes,
trees, and aquatic invertebrates.trees, and aquatic invertebrates.
 This food supply and the cover and isolation from terrestrialThis food supply and the cover and isolation from terrestrial
predators provided by reef beds encourage nesting and rearingpredators provided by reef beds encourage nesting and rearing
of waterfowl such as geese and ducks which are highly valuedof waterfowl such as geese and ducks which are highly valued
by hunters, bird watchers and politicians.by hunters, bird watchers and politicians.

38.  Wetlands also serve as a natural buffer between land and waterWetlands also serve as a natural buffer between land and water
by acting as a sponge for sediments and nutrients, holdingby acting as a sponge for sediments and nutrients, holding
back inflowing matter.back inflowing matter.
 Finally, wetlands are now values for their intrinsic aestheticFinally, wetlands are now values for their intrinsic aesthetic
value and as distinct ecosystems for research by limnologistsvalue and as distinct ecosystems for research by limnologists
and ecologists.and ecologists.

39. ReferencesReferences
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 Soaves, M. (1998). The ocean Our future. Published by Cambridge University Soaves, M. (1998). The ocean Our future. Published by Cambridge University
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 http://saltwaterstudies.com/wp-content/uploads/2015/07/Introduction-Marine-Environment.pdfhttp://saltwaterstudies.com/wp-content/uploads/2015/07/Introduction-Marine-Environment.pdf