*Correspondence author: ZA Ansari, Multi-Faculty college, Dharbandora, Goa
How to cite this article:SM Parvez Al-U, ZA Ansari. Meiofaunal Adaptation to Environmental Variability and Human Trampling of Tropical Sandy Beaches at Goa, India. Oceanogr Fish Open Access J. 2020; 13(1): 555851. DOI:10.19080/OFOAJ.2021.13.555851
Physical disturbances have direct impact on sandy beach ecosystem. The old hypothesis of meiofauna as indicator of disturbance was tested for the assessment of health of sandy beaches. Two sandy beaches in Goa were sampled for meiofauna and sediment properties covering three seasons of the year. There were differences in physical and chemical properties of the sediment of two beaches. The meiofaunal density varied from 386 to 1222⁄ 10 cm2 (mean 712) at Caranzalem and 185 to 662⁄ 10 cm2 (mean 387) at Candolim. The meiofaunal assemblage revealed similar seasonal pattern but significant variation (p<0.01) in total abundance at two beaches. Percent composition of taxa differ at two beaches. The nematodes were the most dominant group with contribution of > 50% followed by harpacticoida polychaeta and turbellaria. General linear model of correlation matrix parameter revealed different relation on two beaches. The N:C ratio suggested its usefulness in disturbance study. The differences in meiofaunal abundance of the two beaches, could be attributed to variability in the physical environment. The trampling has led to changes in relative abundance of meiofaunal taxa at Candolim beach. This study further demonstrated the use of meiofauna in the health assessment of sandy beaches.
Sandy beaches are valuable ecosystem and are main attractant all over world. Beach management focuses largely on maximizing the recreational activities for more beach users at commercial scale. Many beach users have the impression that the compact beach sand is unbreakable and in good health. However, the fact is that numerous influences on sandy beaches like mechanical beach cleaner, trampling and beach fisheries pose serious threat to the ecology of sandy beaches [1,2]. The impact of human recreational activities is more severe than we think . The destructive effect of trampling on larger macrobenthic organisms od sandy beaches have been documented [4,5]. Beach recreation and trampling is reported to lower abundance and diversity of macro benthic invertebrates . However, studies on the effect of anthropogenic activities on smaller metazoans is still rare and negligible . The, knowledge of the effects of different intensities of anthropic activities is essential for the management, conservation, and sustainable tourism policies . The short life span of smaller metazoans, high numerical abundance and remarkable physiological adaptation to extreme conditions make them more
suitable for the assessment of climate change and anthropogenic disturbances such as beach trampling .
Goa is endowed with beautiful sandy beaches all along its 101 km long coast. These beaches are considered as avenues for its economic potential and hence are maintained to attract tourists. Some of the beaches of Goa are crowded by tourists round the year. The increased tourism and the recreational beach activities pose increasing threat to the infauna and biodiversity of sandy beaches . The consequences of human action need to be understood to mitigate its potential impact on the health of an ecosystem in the long run. Several methods using benthos have evolved to check the ecological status and health of marine ecosystem . In this communication we have used the meiofauna as sentinel and indicator of environmental disturbance for health assessment of sandy beaches in Goa, India.
The study was carried out during 2018, covering three seasons, pre-monsoon, monsoon, and post-monsoon, prevailing in this region. Two beaches selected for this study are (1) Caranzalem
which is westward extension of famous Miramar Beach and (2) a
more urbanized and crowded beach at Candolim (Figure 1). The
two beaches differ morpho-dynamically. The Caranzalem beach
is a dissipative shelter estuarine beach with least disturbance
while the Candolim is bustling with activities water sports and
always crowded. The two beaches were covered for systematic
environmental data on physical, chemical, and biological
parameters. The beach hydrodynamic feature was carried out
according to Emery . A horizontal sampling was planned to
study the effect of trampling. The sediment samples for grain size
analysis were collected at each tidal level on only one transect at
each beach. Each transect was divided into 3 equidistance sectors
from its drift line up to the water line. The sediment temperature
was measured with an ordinary thermometer of 0.1-degree
The interstitial water was collected for physical and chemical
parameters. Samples of sediment for meiofauna were collected at
each tide level of both beaches using a 5 cm long Perspex glass
tube covering an area of 10 cm2. Replicate sampling was done at
highest High Tide Level (HTL) Mid Tide Level (MTL) and Low Tide
Level (LTL) below the swash line. On each sampling date sediment
and core samples were collected. The core samples were fixed in
5% buffered formalin Rose Bengal sea water solution and the
meiofauna was extracted by decantation and sieving technique
in the laboratory. A 62micron sieve was used to separate the
meiofauna. The sediment was analyzed for organic carbon and
grain size distribution [13,14]. The chemical and biological
parameters were analyzed by the method given in APHA .
The software program of PRIMER V6 was used for univariate and
multivariate analyses of data.
The profile of the two beaches is given in Figure 2. The
intertidal expanse at Caranzalem was large and varied from
60-70m. The slope of the beach was gentle and gradual. Some
changes during monsoon at lowest low tide level were clear.
The expanse of more exposed Candolim beach was shorter and
varied from 40 to 60m. The slope was sharper and got steeper
during the monsoon season due to direct high wave action of the
sea. The lowest low tide of the two beaches showed a shift during
monsoon season. The temperature of the beach was in the range
of 30.5 to 31.9 oC during pre-monsoon¸ 25.4 to 26.4 oC during
monsoon season and 29.4 to 34.2 oC during post monsoon season
the sediment temperature at Candolim was in the range of 31.4
to 32.8 oC during pre-monsoon 25.7 to 29.4 during monsoon and
27.2 to 31.5 oC in the post monsoon season (Table 1).
Relatively low temperature recorded during monsoon and
there were temperature differences from high to low tide. The
sediment at both beaches consisted of poorly sorted silty sand
with high admixture of fine-grained silt and medium to coarse
sand particles. The mean grain size at Caranzalem was in the
range of 0.35 to 0.38 mm during pre-monsoon season; 0.28
to 0.47 mm during monsoon and 0.28 to 0.47 mm during postmonsoon
season. The sediment tended to increase in grain size
towards the LTL mark. The mean grain size at Candolim beach was
in the range of 0.47 to 0.55 mm during pre-monsoon season, 0.62
to 0.79 mm, and 0.46 to 0.73 mm during post monsoon season.
The sediment showed tendency towards fine sand particles at
supra littoral zone and coarser towards infra littoral zone at both
beaches. There were changes in the percentage composition of
silt clay at all tide levels the sediment organic carbon (mg̷ g) at
Caranzalem was in the range of 2.43 to 4.12 during pre-monsoon’
1 .98 to 2.95 during monsoon and 1.82 to 3.38 during the post
The organic carbon (mg⁄g) at Candolim ranged between
0.85 and 1.52 during pre-monsoon 0.85 to 1.18 during monsoon
and 1.14 to 1.73 during post monsoon. The average chlorophyll
a content (μg⁄g) of the sediment at Caranzalem beach was 0.08
to 0.47 in pre-monsoon‚ 0.06 to 0.29 in monsoon and 0.07 to
0.72 in the post-monsoon. Similarly, the values at Candolim were
0.04 to 0.29 in pre-monsoon‚ 0.06 to 0.18 in monsoon and 0.06
to 0.22 μg⁄g in post-monsoon season. The values were high at
LTL and high concentration was recorded at caranzalem beach.
The result of the analysis of interstitial water of the two beaches
is given in Table 2. The temperature was in the range of 25.6 to
30.8 oC and salinity varied between 22.2 and 31.2 PSU at two sites.
The dissolved oxygen was moderately high, and values ranged
between 4.18 and 5.70 mg/l. The pH values were towards alkaline
side. There was seasonal variation in the physical, chemical, and
morphological properties of the two beaches.
The meiofaunal distribution at two sites are presented in
Table 3. At Caranzalem Beach the total density (number⁄10cm2)
was in the range of 399 to 598⁄ 10 cm2 at HTL‚ 402 to 984/10cm2
at MTL and 386 to 1222/10cm2 at LTL with 712/10cm2 as annual
average. The density at Candolim Beach was 186 to 328 at HTL,
208 to 622 at MTL and 206 to 662/10cm2 at LTL with an annual
average of 387/10cm2. The monsoon season recorded the lowest
density on both beaches while post-monsoon the highest density
at both sites. The numerical count was significantly influenced by
high number of nematoda‚ a feature of tropical beaches. Generally
higher average total meiofaunal densities were recorded at
Caranzalem Beach. The relative abundance (percentage) of
dominant meiofaunal taxa at two beaches is illustrated in Figure
3a and 3b.
The nematodes were the most abundant taxon with 50 to
58% contribution followed by harpacticoid copepod (12-16%),
polychaeta (8-12%) oligochaeta (5-9%) and turbellaria (8-
12%). The Other group comprising of Halacarida‚ Gastrotricha‚
Kinorhynca‚ Foraminiferans and crustacean nauplii formed the
least group. The distribution of meiofauna in the present and
the different taxa was by no means uniform and the order of
domination of taxa varied at different tide levels in different
season. The poor presence of benthic copepod‚ turbellarians‚
foraminifera and Oligochaeta at the HTL and MTL of tourist beach
at Candolim was noticed. There was consistency in the occurrence
of nematode at all tide levels. The difference in the overall
abundance of meiofauna at tidal level of the two beaches was due
to the most abundant group the nematoda.
The correlation matrix is a presentation of the result of
spearman correlation coefficient (r) between sets of variables.
It allows us to see which pair has the highest value. Each value
is tested for its significance. The result is presented in Table
4 and 5. Significant positive correlation between salinity and
temperature (p<0.05, r=0.51), salinity and chlorophyll (p<0.01,
r=0.66), salinity and density (p<0.001, r=0.72) and density and
chlorophyll (p<0.001, r=0.95) at Carasnzalem was recorded.
Similarly, at Candolim the positive significant correlation resulted
between salinity and temperature (p<0.01, r=0.66), salinity and
chlorophyll (p<0.01, r=0.62), density and chlorophyll (p<0.001,
r=0.84), density and dissolved oxygen (p<0.01, r=0.62). The
univariate parameters differed significantly between the two
beaches and between different season (p.˂0.01) (Table 6).
The meiofaunal taxa recorded on the two beaches showed
similarity. The nematodes showed dominance at both beaches
while the crustaceans in particular harpacticoid copepod looked
dim and showed vulnerability towards supra littoral zone. The
controversial nematode: copepod (N:C) ratio has been used in
the past as indicator of organic pollution . We have used the
ratio to check its suitability for the assessment of health of sandy
beaches under stressed condition. The result is given in Table
7. The values showed high degree of variability between two
beaches and between seasons. The ratio produced high values
(>9) at Candolim as compared to Caranzalem. The values ranged
between 9.4 and 20.3 at Candolim and 3.7 and 5.7 at Caranzalem.
The beach is occupied by different types of organisms at
supralittoral, littoral and infralittoral zone. Many beach users
consider sandy beaches as unbreakable and so is the beach
ecosystem. Beach nourishment is an important factor for the
infauna of sandy beaches . The impact of nourishment varies
from case to case, but the influence is direct on the resident
organisms. The beach disturbances will affect the nourishment
directly and mortality of infauna . The physical and chemical
features of the two beaches were normal and followed regular
seasonal cycle as reported earlier .
Relative coarseness in the size of the sand particle at low tide
during the monsoon season at both beaches is a manifestation of
wave action. The beach slope at Candolim tended to be steeper
than the Caranzalem. The morpho dynamic and sediment
granulometary of the two beaches varied . The fine-grained
particles generally have large surface area and thus adsorbs more
organic carbon and nutrient. This was also evident in the present
study. Finer particle with high organic carbon and chlorophyll
supported large population of interstitial fauna . The changes
in interstitial water properties are related to drainage capacity
of capillary water and the evaporation of interstitial water in the
surface layer. It effects the dissolved oxygen and pH and plays
a role in the migration and mortality of interstitial fauna of the
marine biome .
Studies on the effect of human trampling have reported
different response by benthic organisms of sandy beaches [21,22].
Macrofaunal response have been found different than meiofauna.
Moffett et al  reported that different trampling intensities gave
varied response by different macrofaunal species. Rossi et al 
have indicated that trampling clearly modified the abundance and
population dynamics of the clam Macoma balthica (L.) and the
cockle Cerastoderma edule (L.). There was a negative impact on
adults of both species, probably because footsteps directly killed
or buried the animals, provoking asphyxia. Available accounts on
the effect of trampling associated to the digging for bait collection
report a general decrease in the numbers of tube-dwelling, subsurface
deposit-feeders and deep-burrowing forms .
In a manipulative trampling study Martinez et al. 
reported that trampled plots showed negative shift in invertebrate
community as compared to controlled plots of the coralline
sandy surface. Similarly, significant effect of trampling on the
occurrence of meiofauna taxa and their relative abundance have
been reported on the other sandy beaches. Gheskiere et al. 
has reported that tourism related activities have negative effect
on sandy beach meiofauna. Significant reduction in meiofaunal
density of a sandy beach due to cyclone was reported recently 
with fast recovery subsequently. Sarmento et al.‚ Sun et al, Santos
et al. [28-30] has also reported negative effect with significant
reduction in numerical abundance of a few meiofaunal taxa due to
human trampling of beaches. The disturbances have led to change
in the taxa and their relative abundance in this study. The result of
this study supports the severity and negative impact of trampling
reported by others.
The factors responsible for the distribution of organisms in
the intertidal zone of sandy beaches has been well studied and
reported [2,31]. The anthropogenic impact has a general negative
effect on meiofauna . The fluctuation in the meiofauna of
tropical beaches is a natural phenomenon . The meiofaunal
distribution in the present study revealed the pattern and faunal
dominance observed by others on the sandy beaches of the
central west coast of India [18,33]. The population density at
Caranzalem was higher than that of Candolim. A comparison of
faunal abundance with old data revealed that at Caranzalem no
noticeable changes found while at Candolim significant lowering
in number was recorded (Table 8).
While studying the pollution effect of petroleum hydrocarbon,
(TPH) on intertidal benthos of Sinquerim beach at Goa, Ingole et
al.  reported significantly low density of meiofauna (22-64 /10
cm2) initially which increased subsequently to 1057/10cm2 with
parallel reduction in the concentration of sediment petroleum
hydrocarbon. In another study significant impoverishment in
meiofauna number of sandy beaches due to oil spillage and
anthropogenic disturbance on west coast of India was reported
. The meiofauna are known for high resilient nature and
have shown rebuilding capacity in a short time after any
environmental disturbance . Candolim also appeared to have
undergone changes in benthic life due to disturbance caused by
regular mechanical cleaning and heavy trampling. The ecological
resilience of meiofauna of such beaches with high trampling is
in question . The changes in benthic life and the recovery
rates are mediated by a combination of physical, chemical, and
biological factors that differ in their relative importance in
different habitats .
The effect of persistent human trampling could have a
negative impact on meiofauna of sandy beaches like Candolim
beach of the present study as compared to a non- disturbed beach
at Caranzalem. The differences recorded in the metazoans of the
two beaches may be the result of both environmental variation
and beach disturbance caused by anthropogenic pressure. The
severity of the trampling on meiofauna discussed earlier in this
paper agrees with the reports of earlier studies made elsewhere.
It has been demonstrated that N⁄C ratio is useful bioindicator of
organic pollution of sandy beaches . In a recent study Santos
et al  have reported high N⁄C ratio (more than 10) of a sandy
beach having large human trampling at sandy beaches in Brazil.
The elevated N:C ratio at Candolim during all season of the present
study is support the use of controversial N:C ratio in the health
assessment of beaches and agrees with earlier result [30, 36].
High mortality in harpacticoid due to their sensitive nature led
to reduction in number which is responsible for higher N:C values
at more disturbed beach of Candolim. Nematodes are known for
high physiological adaptation and can live under low oxygen.
The sensitive nature of meiobenthos anthropogenic pressure
is also demonstrated by others [20,26]. The total population
showed significant seasonal variation (Two-way ANOVA, p<0.01,
F=26.7). It may be attributed to natural changes. The extensive
environmental disruption caused by annual monsoon resulting in
heavy mortality of benthic organism is reported from the beaches
of central west coast of India [18,38]. Such changes are regularly
occurring and not limited to anthropogenic beach disturbances.
The present study supports the hypothesis that meiofauna
are good indicator of anthropogenic pressure and should be
included in the health assessment studies of sandy beaches. The
result of the present study differs in many respects from others.
The meiofaunal community appeared to be more related to the
physical environment and recreational activities of the beach.
It suggests that trampling, in the absence of any pollution, may
have caused reduction in the fauna and mortality of some benthic
organisms as reported earlier [26,29]. In Goa, the tourism related
industries are doing well but the damage caused is not ascertained
fully. The increase in water sports, disturbance of sensitive
habitats, beach driving, beach litter and sanitation are playing
their role in effecting the native fauna adversely. Such pressure
is expected to alter the ecological functioning and beach dynamic
. This will affect the beach life at individual and community
level. The recovery will depend on disturbance persistence and
its intensity [39-42].
The environmental variables are fundamental in the
interpretation of faunal distribution. Meiofauna offer several
advantages in the study of anthropogenic impacts and should be a
part of all studies related to environmental disturbances of sandy
beaches. The physical disturbance and littering of the beaches
with persistent trampling may cause severe impoverishment
of fauna. The nematode: copepods are valuable taxonomic
component of environmental effects. The management and
conservation strategies for the development of beach is essential
and all studies should invariably include the impact on meiofauna.
A more detailed annual study and monitoring of sandy beaches
using meiobenthos is suggested in future to mitigate the impact
and save the biodiversity of these ecotones. Our understanding of
the tourism as a safe and clean industry needs to be considered
with caution under beach aesthetic and safety consideration.
we re-emphasize the usefulness of meiobenthos in the health
assessment of sandy beaches.
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