Bryophytes as ecological indicators

BRYOPHYTES AS BIOINDICATORS
OF WATER AND AIR POLLUTION
ALEN SHAJI
P1914015

BRYOPHYTES - INTRODUCTION
 Bryophytes are a diverse group of land plants.
 Have large ecological impact.
 23,000 described species world
wide.
 Largest group of land plants
except for the flowering plants.
 Integral part of natural
environment of forest ecosystems.
 Bryophytes are of small size.
 Some of them attain a height up to half metre or a little
more.
 Store large amount of water, nutrients and carbon in
their biomass.

 In peatlands, bryophytes function as carbon sinks,
which is a matter of great concern when considered
with the rise of global carbon
dioxide level.
 Ability to remain alive for a
long period without water even
under high temperature, and
then resume photosynthesis
within seconds after being
moistened by rain or dew.

 Most bryophytes are ectohydric, i.e., ability to
absorb water, inorganic nutrients and mineral
elements directly
from the atmosphere
rather than the soil and
substratum.
 Bryophytes possess
short-lived sporophytic
and dominant
gametophytic phase.

 Various modes of reproduction play an important
role in the life cycle of bryophytes especially in
stands within high disturbance.
 Able to grow in stressful conditions like cold,
drought, shades and in nutrient poverty conditions.

 Bryophytes play an efficient role to filter the
nutrients reaching to soil by
absorbing them directly from the
atmosphere in liquid phase.
 Bryophytes protect the soil
against erosion due to their
netted and webbed protonemata
and gametophores to cover the
exposed substrata and help in
increasing water-holding capacity
of the soil.

 Role of bryophytes in an ecosystem is governed by four
properties,
1] Ability to establish soils.
2] To trap and hold moisture.
3] To exchange cations.
4] To tolerate desiccation.
 Bryophytes have ecological association with
microorganisms, protozoans, rotifers, nematodes,
earthworms, molluscs, insects, spiders and many other
invertebrates.
 Bryophytes furnish a favourable substratum and seed
bed for the establishment of seedlings of higher plants.
 They provide congenial habitat for nitrogen-fixing
Cyanophyceae, e.g., Nostoc, Scytonema.
 Mosses alone account about 75% of the annual
accumulation of phosphorus.

 Some taxa such as Ceratodon purpureus and
Funaria hygrometrica produce sporophytes under
highly polluted conditions but differ in reproductive
behaviour as it shows differences in tolerance.
 Tortula laevipila produces few sporophytes in urban
population in comparison to rural area.
 Highest mercury contents 12,100 Hg g–1 has been
reported from the basal segments of Jungermannia
vulcanicola growing in an acidic stream.
 Atmospheric pollutants along with some minerals
directly enter the cell of the bryophytes.
 Ultimate survival of bryophytes is critically
dependent on the preservation of their natural
habitats.

ECOLOGY OF BRYOPHYTES
 Ecology of bryophytes means the study of the
relation of individual
bryophyte plant
communities to
complex environment.
 The place where a
bryophyte or
community of
bryophytes lives is
called its habitat.

 Bryophytes grow in different habitats which are as
follows;
1] TERRESTRIAL.
2] AQUATIC.
a] Fresh water.
b] Marine water.
3] EPIPHYTIC OR CORTICOLOUS.
a] Obligate epilithic or saxicolous.
b] Facultative epilithic or saxicolous.
4] EPIPHYLLOUS OR FOLIICOLOUS.
a] Obligate epiphyllous or foliicolous.
b] Facultative epiphyllous or foliicolous.
5] DESERT BRYOPHYTES.

 Bryophytes play important role in an ecosystem in
many ways,
1] Great capacity to stabilize soil, particularly
mosses are very effective and successful soil binder
and nutrient trapper.
2] High water holding capacity and ability to
tolerate desiccation.
3] Form a moist wet ground to form a
cushion; which ultimately helps to grow the other
vascular seedlings later; This maintains the high
humidity regime within such forest.
4] Filtering takes place through fall and runoff
water through the bryophyte mat and peat using
cation exchange system.

BRYOPHYTES AS BIOINDICATORS
 The habitat diversity, structural simplicity,
totipotency, rapid rate of multiplication and high
metal accumulation capacity make bryophytes an
ideal organism for pollution studies.
 Decline and absence of bryophyte populations
especially epiphytes is a phenomenon primarily
induced by air pollution caused by gaseous and
particulate pollutants.
 There are two categories of bryophytes in response
to pollution;

1] Which are very sensitive to pollution and show
visible symptoms of injury even in the presence of
minute quantities of pollutants. This serve as good
indicators of the degree of pollution and also of the
nature of pollutant.
2] which have the capacity to absorb and retain
pollutants in quantities much higher than those
absorbed by other plant groups growing in the
same habitat. These plants trap and prevent
recycling of such pollutants in the ecosystem for
different periods of time. Analysis of such plants
gives a fair idea about the degree of metal
pollution.

POLLUTANTS
 Pollutants may be gaseous such as carbon monoxide (CO),
fluorides, hydrocarbons (HC), hydrogen sulphide (H2S),
nitrogen oxides (NO), Ozone (O3), sulphur dioxide (SO2),
aldehydes, lead and automobile exhaust fumes.
 Nitrogen oxides have also greatly increased in the cities with
the rise of use of automobile.
 Particulate pollutants are dust, particles of metallic oxides,
coal, soot and fly ash, cement, liquid particles, heavy metal
and radioactive materials.
 Ozone (O3) is a secondary pollutant formed by the action of
sunlight on nitrogen dioxide and on certain hydrocarbons.
 Air pollutant either in a gaseous state mixed with air or in a
liquid state affected by dew, rain, or snow, will be noxious to
bryophytes attached to the bark.

EFFECT OF POLLUTANTS ON BRYOPHYTES
 Bryophytes have been disappearing from urban
industrial environments
because of their sensitivity to
polluted air.
 Air pollution inhibits
gametangial formation and
sexual reproduction in
bryophytes.

 They also reduce photosynthesis by degrading
chlorophyll and growth of
plants and eventually cause
their death.
 When the metal enters the
cell, it inhibits the
photosynthetic activity.
 Enzymes and membrane are
poisoned when a heavy metal
gains access to the cell
interiors.

 It is evidenced that when the pollution level goes
down, the percentage
frequency of species
goes up, which subsequently
increases the
fertility percentage.
 Bryophytes die within a short
period of time depending on
the level of pollution, when
transferred along with their
substrates from unpolluted to polluted areas in a city
or around a factory.

 The common symptoms of injury are plasmolysis
and chlorophyll degradation
in the leaf cells.
 SO2 exposed plants showed
brownish spots on the
chloroplasts and plasmolysis
in cells of leaves which
contributed to the ultimate
death of the plants.

 Ozone uptake by the plant species often results in
acute injury, premature ageing and senescence.
 Bryophytes show impairment of photosynthesis or
increased membrane leakage when subjected to an
acute (150 p.p.b) ozone exposure.
 Several species of Sphagnum species were found to
be chronic to O3 exposure.
 Bryophytes are able to concentrate heavy metals in
large amounts than that of vascular plants.
 The older tissues of the plant have higher
concentrations of the metallic ions as compared to
the younger portions.

 The ability of mosses to accumulate heavy metals
depends upon the total
leaf surface and the
number of thin walled
parenchymatous cells.
 Atrichum undulatum is
highly sensitive to air
pollution and proves best
as a bioindicator.
 Ceratodon purpureus is
not a good indicator
because its leaves have
a small surface and
contains many thick walled
cells.

 Carpet forming bryophytes has proved to be rapid
and inexpensive
method for surveying
heavy metal
deposition in the
terrestrial ecosystem.
 Accumulation of
mercury is found
greater
in Dicranum scoparium.

 The gametophytes of moss can accumulate iron 5-10
times more readily than the vascular plants.
 The concentration of Al, Ba, Cr, Cu, Fe, Ga, Ni, Pb, Ag,
Ti, Vi, Zn and Zr were higher in bryophytes than those
in angiosperms.
 Bryophytes are able to concentrate rare earth
elements.
 Elements which are rarely founds in other plants were
found in bryophytes.
 Bi were found in the thallose liverworts like
Conocephalum conicum and Marchantia polymorpha,
Sn in the saxicolous mosses Grimmia laevigata and
Hedwigia ciliata and Ag in Atrichum angusatum and
Polytrichum commune. Cu, Pb and B are found in the
substrate of Mielichhoferia.

 Accumulation of mercury (Hg) is found greater in
Dicranum scoparium than Polytrichum commune
which is due to the differences in their life forms.
 Some bryophytes are metal tolerant and are able to
withstand levels of heavy metals that are toxic to
other species.
 Marchantia polymorpha, Solenostoma crenulata,
Ceratodon purpureus and Funaria hygrometrica are
some of the metal tolerant populations.
 Bryophytes growing on stone walls can tolerate
higher levels of pollution than those of tree trunks.

POLLUTION AND HEAVY METAL
INDICATOR
 Bryophytes are bioindicators of air, water pollution
and accumulators of heavy metals.
 Communities of mosses, lichens and liverworts
reduce in size over a period in such disturbed
environmental conditions (air pollution).
 Mosses disappear from such polluted areas accept
a few tolerant species; Bryum, Ceratodon,
Dicranoweisia, Funaria, Hyophila and Tortula.
 Pylaisiella and Orthotrichum are shown to change
the colour of leaves due to chlorophyll degeneration
when they are exposed to HF polluted area.

 Bryophytes are very sensitive to hydrogen fluoride,
even a low concentration
of HF (0.001 to 0.1 ppm)
and show symptoms of
injury.
 Even a low concentration
of SO2 inhabits the
flourishing of the mosses,
as protonemata are
especially sensitive to the
pollutant.

 Sphagnum have a peculiar character to bind
radioactive compounds
through cation exchange and
also used for purifying
contamination of waste
water.
 Some species of
Anomodon, Dicranum,
Eurhynchium, Leucodon,
Mnium, Rhynchostegium
and Thuidium are able to
accumulate Cesium.

 Species of Brachythecium, Buxbaumia and Grimmia
are able to concentrate much strontium than that
found in their substrata.
 Some terrestrial bryophytes accumulate uranium.
 High levels of pollutants like fluoride, sulphur
dioxide, acidified rain and heavy metals are
responsible to inhibit sporophyte growth in many
moss species.
 Aquatic bryophytes are the best monitoring agents
for heavy metal pollution as they are able to
concentrate these heavy metals and can release
these metals only after decomposition.

 High concentration of cadmium in some bryophytes
shows a distinct change in pigmentation and growth
rate of these
lower plants.
 In Marchantia
and Funaria, the
zinc concentration
(> 50 ppm) reduce
the spore germination.
 Species of Bryum, Dicranella and Polytrichum are
able to tolerate high levels of zinc (55000 ppm),
cadmium (610 ppm) and copper (2700 ppm) in their
tissue.

BRYOPHYTES AS BIOINDICATORS OF WATER
POLLUTION
 Life form of bryophytes is very simple so they are
comparatively more
affected by polluted
waters than other groups.
 Polluted water also
affects the benthic and
marginal soils thus it
directly affects the aquatic
bryoflora and directly
or indirectly affects those
bryophytes which grow on its banks.

 Contamination – Addition of unwanted organisms
or nutrients pollution
to widely used for both
addition and deletion of
important elements and
organisms.
 Pollution – Any foreign
particles [which is living
or non living or both] that seen more in quantity than
permmisable amount and become injurious to
living organism.

 Pollutants change the quality of water which is
determined on the basis of several physico-chemical
and biological parameters.
 Physico-chemical parameters generally affect the
plant life.
 Because of their simple plant body, the bryophytes
appear to be sensitive to polluted waters due to
following reasons;
1] Plant body is gametophytic; very small, soft and
delicate; thus bryophytes mostly prefer moist places
to grow.
2] plants lack well developed vascular system
comprising of xylem and phloem.

3] Plants lack well developed root system but develop
rhizoids which
help in absorption of
water.
4] Water is essential
for fertilization.
 Bryophytes absorb the
water either by rhizoids
or by entire surface of
plant or by both ways.
 Movement of water
within plant body of
a bryophyte takes place either by central strand or by free
space of cell to cell or external capillary space.

 Therefore, if water is polluted it certainly affects the life
forms of bryophytes
including external
morphology,
anatomy, fertilization,
spore
germination and
physiology.
 Therefore, bryophytes
are
more sensitive to
water
pollution than air
pollution.

 Bryophytes can provide an integrated information
of pollution within a system.
 Some aquatic bryophytes which are pollution
tolerant species have been recommended to
monitor the levels of pollution in water; these
species are;
1] Amblystegium riparium – It is a moss which is
cosmopolitan in distribution and found in running
and stagnant water or sewage rich in nutrition.
2] Eurhynechium riparioides – It is a moss which is
found only in northern region of world; it grows in
ponds and rivers rich in nutrition; reported
pollutant contents and heavy metals of these
waters.

3] Fontinalis antipyretica – A moss which is also
restricted in northern part and grows in both
stagnant and running water; analyse cu and pb in
the moss.
4] Fontinalis squamosa – It is also restricted in
distribution; reported the details of pollutants and
heavy metals.
BRYOPHYTES WHICH APPEAR ON THE BANKS OF
RIVER GANGA AND ARE AFFECTED BY RIVER
WATER QUALITY
1] Riccia gangetica – A pollution tollerant species;
tubercualte rhizpoids and marginal scales are more
developed in highly polluted sites; it is a
monoecious species.

2] Riccia frostii – A pollution sensitive species which
grows in lesser
polluted sites;
sensitivity towards
polluted water is
due to presence of
only smooth walled
rhizoids, absence
of scales and separate male and female plants.
3] Funaria hygrometrica – Found only on those sites
where cremation takes place and benthic and
marginal soil is rich in P an Ca.

4] Physcomitrium indicum – It is a moss which
absorbs the heavy metals.
 Bryophytes growing on the
river banks of Ganga absorb
very high levels of heavy
metals like Cr, Zn, and Ni.

THE MAIN ADVANTAGES OF USING BRYOPHYTES AS INDICTORS
IN AQUATIC HABITATS ARE;
1] There is a constant uptake of pollutants from water over the
entire surface.
2] Most aquatic bryophytes are fairly tolerant against a wide
range of pollutants like heavy metals, which they tend to
accumulate.
3] Bryophytes react quickly to changes in water quality
according to increases or decreases in nutrients or toxic
substances.
4] They form stable and homogeneous populations and they
show green leaves and active metabolism throughout the
year, which favours them over higher plants which lie
dormant during the winter season, or algae which often show
restricted life spans.
5] There is only a limited number of submerged species in the
northern hemisphere, which is in contrast to sometimes
enormous biomass easily to identify in most of the cases.

 Based on their ability either to accumulate
pollutants or
respond sensitively
to changes in
water quality,
bryophytes are
used either as
accumulation
indicators or the bryophyte species assemblages are
investigated for indication of water quality
(including the nutrient status) or changes in the pH.

BRYOPHYTES AS BIOINDICATORS OF AIR
POLLUTION
 Bryophytes are very sensitive to air pollution.
 Air becomes polluted
when air pollutants,
which are beyond
permissible limits and
injurious to living
organism, are found mixed
within it.
According to World Health
Organisation [WHO], air pollution may be defined as
limited to situations in which the outdoor ambient
atmosphere contains materials in concentrations which
are harmful to man and his environment.

 Classification of air pollution.
1] Combustion – From fuel
burning, transportation and
open burning dumps.
2] Manufacturing process –
Chemical plants, metallurgical
plants and waste recovery.
3] Agricultural activities –
Crop spraying as weed and pest
control, gases evolved from
the fields.

4] Solvent usage – Spray painting, solvent extraction
inks, solvent cleaning.
5] Nuclear energy – Fuel fabrication, ore
preparation,nuclear device
testing, spent fuel processing.

 Classification of air pollutants.
1] In the form of gases;
a] Sulphur dioxide.
b] Flouride.
c] Hydrogen sulphide.
d] Ozone.
e] Nitrogen dioxide.
f] Ammonia.
g] Methane.
h] Petrolium vapours.
i] Hydrogen flouride.

2] In the form of particulate matters – as solids and
liquid aerosols.
3] In the form of microorganism and
spores or pollens of plants.
 Some species of bryophytes are
pollution tolerant and some are
pollution sensitive.
 Within last century the
belgium bryoflora has lost 20 species of
liverworts and 94 species of mosses.
 Dutch bryoflora was depleted
by 15% of terrestrial and 13% of epiphytics.
 In amsterdam 23 species of bryophytes are now extict
from the city.

 Air pollutants affect the habitat and growth forms
of bryophytes.
 Sensitivity of
bryophytes towards air
pollution increases from
terricolous to saxicolous
and corticolous species.
 Moss protonema is
more sensitive than its
mature gametophores.

 Tortula princeps, Bryum rubrum, Ceratodon
purpureus and Pohila cruda
are able to tolerate levels of
pollution on stone walls than
on tree trunks.
 Growth form of bryophytes
in respect to tolerance of
pollution gradually increases
from tall turf, large cushion
or leafy liverworts to smooth and
small cushion and finally most resistant are sort turf
and thalloid liverworts.

 Fertility of bryophytes decreases as pollution level
increases.
 Bryophyte species sensitive to air pollution are;
1] ulota crispa.
2] Platydictya subtile.
3] Paraleucobryum longifolium.
4] Frullania muscicola.
5] Trocholejeunea sandvicensis.
6] Lophocolea minor.

CONCLUSION
 Bryophytes have been an
essential group in the field of
bioindication for at least four
decades.
 Bryophytes should be
acknowledged by law as
indicator species for the
setting and control of
deposition limits for heavy
metal imissions.
 Bryophytes proved well in
many fields of environmental control.

 Bryophytes seem to become an important group of
species especially
in the field of climate
change research in
the future, which will
be a major task in the
next years.
 Bryophytes which
are mostly small in
size, are essentially for the integral understanding
and control of the present state and future
development of our environment.

 Bryophytes have an important role with respect to
environmental conditions.
 It is proved that these are the first colonies of the
terrestrial habitats and represent a bridge between
the Pteridophytes on one hand and the Algae on
the other.

 Species richness of Bryophytes is very high and placed
next to Angiosperms
and has a great capability to
grow even in adverse
conditions, while other
vascular plants are not able to
do so, bryophytes are the best
pollution indicators.
 However, this lower group
of plants received lesser
attention in this country and
remained neglected in
exploration, due to their less
direct economic potentials.

 At present, the impact upon these lower plants is more
adverse due to
global problems, which
is governed by several
factors like; global
warming, shifting of
monsoon,drought,
landslides, earthquakes,
manmade pollution
and habitat distraction
by broad constructions and post effect of tourism.

 More bryo-exploration is essential for the
unexplored areas and necessary steps should be
taken up for their
conservation.
 India one of the
12-megabiodiversity
countries of the
world, possesses a
large area and a
variety of phytoclimatic conditions which contribute
to great diversity of the flora.

 Pande (1958) divided these zones in to 7 bryogeographical
regions namely the Western and Eastern Himalaya, Punjab
and west Rajasthan, Gangetic plains, Central India, Deccan
Plateau and the Western and Eastern Ghats.
 Bryophytes are ecologically significant and play a key role
in ecosystem dynamics.

 They cover the barren soil and conserve the soil
and nutrients, provide habitats for invertebrates
and maintain water balance in the forest.
 Bryophytes contain some specific compounds,
which possess antibiotic and antimicrobial
properties.

REFERENCES
 B. R. Vashishta: Bryophytes (2008): S. CHAND AND COMPANY
LIMITED, RAMNAGAR, NEW DELHI- 110055: Pp. 450-452.
 Kumar Gupta & Mukesh Kumar: Biodiversity of Lower Plants
(2013): Bryophytes and Ecosystem (Article - January 2014):
YATEESH MOHAN BAHUGUNA, SUMEET GAIROLA, D.P.
SEMWAL, P.L. UNIYAL AND A.B. BHATT: Pp. 279-296.
 B.A. Markert, A.M. Breure, H.G. Zechmeister, editors © 2003
Elsevier Science Ltd: Bioindicators and biomonitors (2003):
Bryophytes (Article - June 2003): Harald G. Zechmeister,
Krystyna Grodzińska and Grazyna Szarek-Łukaszewska: Pp.
329-364.
 H. Govindapyari, M. Leleeka, M. Nivedita and P. L. Uniyal:
Bryophytes: indicators and monitoring agents of pollution
[Article] 17 September 2009: Pp. 35-41.

Bryophytes as ecological indicators

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