Distribution and Abundance of Gelatinous Zooplankton along Tamil Nadu Coastal Waters
P. Sampath Kumar,
C. Prasanna Kumar,
B. Akbar John
The distribution and abundance of the gelatinous zooplankton
namely hydromedusae, scyphomedusae, siphonophore, ctenophore, salps, doliolids,
appendicularians and chaetognaths were investigated in two seasons at seven
stations in East Tamil Nadu coast, India. The occurrences of gelatinous zooplankton
were observed to be more in summer than in winter. However, the composition
of different species in each group varied from all the stations and seasons.
Apart from the individual variation in seasonal distribution, most of the species
appeared to be cosmopolitan in the Indian waters. A total of 34 species from
summer and 17 species from winter were recorded during the present study. The
hydromedusae were dominant in both the seasons of the study period. Ephyrae
of the scyphomedusae were also noticed in both the seasons.
to cite this article:
G. Iyyapparajanarasimapallavan, P. Sampath Kumar, C. Prasanna Kumar, K.C.A. Jalal, B.Y. Kamaruzzaman and B. Akbar John, 2013. Distribution and Abundance of Gelatinous Zooplankton along Tamil Nadu Coastal Waters. Journal of Biological Sciences, 13: 18-25.
Received: October 01, 2012;
Accepted: October 20, 2012;
Published: February 09, 2013
Gelatinous zooplankton are taxonomically diverse group of macroplankton playing
vital role in structuring coastal and estuarine ecosystems (Mahboob
and Zahid, 2002; Ali et al., 2003; Guher
et al., 2004; Suchman and Brodeur, 2005),
whose diversity is less explored due to their fragile nature (Raskoff
et al., 2003). They include medusae, siphonophores, ctenophores,
chaetognaths, pteropods, heteropods, appendicularians, salps, doliolids and
pyrosomes (Ahmed et al., 2007; Oueda
et al., 2007). Gelatinous zooplankton are widely distributed in all
the major ocean waters. However, they are the least understood of all planktonic
animal groups (Raskoff et al., 2003; Saravanakumar
et al., 2007; El-Sherbiny et al., 2007;
Rahimibashar et al., 2009; Kumar
and Perumal, 2011). They occur in all the oceans from the surface to the
seafloor. In addition of being beautiful, these drifters are capable of eating
enormous amounts of prey and may compete with fishes for these natural resources.
They form an important integral part of the ecosystem, the notable gap in understanding
the linkages between primary and secondary productivity in the oceans being
the lack of knowledge about gelatinous zooplankton (Raskoff
et al., 2005). In recent years, strong and sustained increments of
gelatinous organism populations have been recorded in different geographic marine
areas (Mills, 2001; Brodeur et
al., 2002). These proliferations have caused important changes in the
pelagic community structure due to the impact of gelatinous organisms as consumers
and competitors of zooplankton and fish larvae (Matsakis
and Conover, 1991; Purcell, 1997). Abundance of
gelatinous zooplankton has been implicated in phytoplankton blooms throughout
trophic cascading (Lindahl and Hernroth, 1983; Verity
and Smetacek, 1996; Schneider and Behrends, 1998).
They are also able to maintain feeding rates proportional to food concentration
over a wide range and allowing them to efficiently exploit high prey densities
(Bamstedt, 1990, 1998; Sornes
and Aksnes, 2004). These life history characteristics may at times result
in a competitive edge in resource utilization with respect to each other and
slower growing consumers of zooplankton e.g., many crustaceans and fishes. It
also contributes to the naturally pulsed occurrence of many species of gelatinous
predators in the plankton as well as the extraordinary blooms of jellies frequently
observed (Arai, 1992; Boero et
al., 2001). Among these groups, medusae, siphonophores and ctenophores
are very abundant and dense aggregates have been recorded in various coastal
settings of the world (Palma and Rosales, 1995; Palma
and Apablaza, 2004). The sudden appearance of medusa with an apparently
abnormal abundance of one or a few species (medusa blooms) is a
common but as yet enigmatic characteristic of gelatinous plankton life histories.
These events are usually noticed and reported when massive appearances of conspicuous
stinging jellyfish occur near the coastal zone significantly and visibly affecting
human activities such as tourism and fisheries (Haddad et
al., 2002). The majority of the published records on gelatinous zooplankton
are from the other part of the countries. Until recently, there were only few
records on gelatinous zooplankton along Tamil Nadu coastal waters. The present
study reports on the occurrence and abundance of gelatinous zooplankton along
Tamil Nadu coastal waters.
MATERIALS AND METHODS
Sampling sites: The Bay of Bengal is located in the eastern side of
India which is a tropical basin and experiences monsoonal wind force that reverses
its direction semi-annually. A large number of rivers such as the Irrawaddy,
Brahmaputra, Ganges, Godavari, Krishna and Cauvery discharge into the Bay of
Bengal. The present study has been carried out in seven different coastal environmental
stations along Tamil Nadu coastal waters from station 1 (8°7'N, 77°33'E)
to station 7 (13°06'N, 80°17'E) (Table 1) and the
map showing the study area is depicted in Fig. 1. The investigations
were carried out on two different seasons during summer and winter 2008.
Sampling procedure: The samples were collected using plankton net with
a mesh size of 200 μm and 50 cm diameter. After the net operations, the
gelatinous organisms were fixed in 5% formalin solution in seawater for subsequent
|| GPS locations of the sampling stations
||Map of the study area, 1: Kanyakumari, 2: Mandapam, 3: Thondi,
4: Nagapattinam, 5: Parangipettai, 6: Puducherry, 7: Chennai
The gelatinous zooplankton collection were made in different ways, not only
by the plankton net and also by using scoop net, hand pick, because of their
size variation from 2 mm to 20 cm, especially Scyphomedusae group.
Identification key: The Identification of gelatinous zooplankton was
based on the taxonomic keys described by various authors (Kirkpatrick
and Pugh, 1984; Kramp, 1959, 1961;
Russell, 1953, 1970).
Data analysis: Biodiversity indices were calculated by following the
standard formula of Shannon and Weaver (1949) diversity
index (H), richness (D); Pielou (1966) evenness.
Pearson correlation co-efficient (r) values were calculated to understand the
relationships between distribution, diversity of Gelatinous zooplankton and
Species composition and abundance of gelatinous zooplankton: A total
of eight groups of gelatinous zooplankton were observed during the study period.
A total of 14 species of hydromedusae in summer and 5 species in winter were
recorded, among this, the maximum number of species were recorded from station
1 whereas, the minimum were from stations such as station 2, 3 and 7. In winter,
the maximum numbers of species were recorded from station 5 whereas, the minimum
were from station 6 and 7. A total of 5 species of Scyphomedusae in summer and
3 species from winter were recorded. Among this the maximum numbers of species
were recorded from station 5 whereas, the minimum were from station 3 and 6.
The maximum numbers of species were recorded from station 5, whereas the minimum
were from station 2. A total of 5 species of Siphonophores in summer and 2 species
from winter were recorded. The maximum numbers of species were recorded from
station 5 whereas the minimum were from station 1 and 7. In winter, the maximum
numbers of species were recorded from station 5 whereas the minimum were from
station 3. Only one species of Ctenophores in both the seasons was recorded,
the Pleurobrachia sp. was observed in this group. This was recorded from
station 1 and 5 whereas no species of this group were recorded from station
2, 3, 4, 6 and 7. A total of 3 species from the group of salps and doliolids
in summer and 3 species from winter were recorded. The maximum numbers of species
of this group were recorded from station 5 whereas the minimum was from station
3. In winter, the maximum number of species of this group was recorded from
station 3 whereas the minimum was from station 2. A total of 2 species of Appendicularians
in summer and 2 species from winter were recorded. The Oikopleura species
were observed in both the seasons. In summer the maximum numbers of species
of this group were recorded from station 5 whereas the minimum was from station
6. In winter, the maximum number of species of this group was recorded from
station 6 whereas the minimum was from station 2 and 3. A total of 3 species
of Chaetognaths from summer and 2 species from winter were recorded. The maximum
numbers of species were recorded from station 5 whereas the minimum was from
station 2 and station 7. In winter, the maximum number of species were recorded
from station 3 where as the minimum were from station 2 and station 7. The details
of species composition and abundance of gelatinous zooplankton are depicted
Table 2-5, respectively.
Diversity indices of gelatinous zooplankton: The detailed values of the different diversity indices are depicted in the Table 4 and 5. The species diversity ranged from 2.174 to 2.742 during summer and 1.274 to 2.277 during winter. The minimum species diversity was recorded during winter at station 3 and the maximum species diversity was recorded during summer at station 1. The species richness ranged from 0.8193 to 0.9105 during summer and 0.6786 to 0.8889 during winter. The minimum species diversity was recorded during winter at station 3 and the maximum species diversity was recorded during summer at station 2. The species richness ranged from 0.7843 to 0.9249 during summer and 0.7913 to 0.9496 during winter. The minimum species diversity was recorded during summer at station 4 and the maximum species diversity was recorded during winter at station 5.
Correlation between different physicochemical parameters and gelatinous zooplankton diversity: The present study found that the diversity and abundance of the gelatinous zooplankton are highly influenced by the various physicochemical parameters prevailing in the study area. There was positive correlation between the abundance of gelatinous zooplankton and salinity, temperature and pH of the study area, whereas there was a negative correlation between dissolved oxygen and abundance of gelatinous zooplankton. This trend was similar in both the summer and winter seasons (Table 6).
|| Distribution and abundance of gelatinous zooplankton in summer
|ES: Eudoxid stage, EL: Ephyra larvae, O: Occurrence, A: Abundance
(ind L-1), Stations 1: Kanyakumari, 2: Mandapam, 3: Thondi, 4:
Nagapattinam, 5: Parangipettai, 6: Puducherry, 7: Chennai
|| Distribution and abundance of gelatinous zooplankton in winter
|ES: Eudoxid stage, EL: Ephyra larvae, O: Occurrence, A: Abundance
(ind L-1), 1: Kanyakumari, 2: Mandapam, 3: Thondi, 4: Nagapattinam,
5: Parangipettai, 6: Puducherry, 7: Chennai
|| Diversity indices of gelatinous zooplankton during summer
|1: Kanyakumari, 2: Mandapam, 3: Thondi, 4: Nagapattinam,
5: Parangipettai, 6: Puducherry, 7: Chennai
|| Diversity indices of gelatinous zooplankton during winter
|1: Kanyakumari, 2: Mandapam, 3: Thondi, 4: Nagapattinam, 5:
Parangipettai, 6: Puducherry, 7: Chennai
|| Correlation matrix between various parameters and diversity
and abundance of zooplankton
|The results are pooled values of the total data obtained,
n = 10, *Significant at p<0.05, AT: Atmospheric temperature, WT: Water
temperature, DO: Dissolved oxygen
There were few records on whole gelatinous zooplankton from the study area,
in this connection the present study were conducted and a total of eight groups
of gelatinous zooplankton were observed during the study period. They are hydromedusae,
scyphomedusae, siphonophores, ctenophores, salps, doliolids, appendicularians
and chaetognaths in both the seasons. However, the composition of different
species in each group varied from all the stations and seasons. The seasonal
distribution and abundance of planktonic cnidarians is primarily governed by
factors controlling the release of the larvae. Temperature, food abundance,
salinity and the ratio of light to dark are known to affect the liberation of
medusae from hydroids (Arai, 1992). Apart from the individual
variation in seasonal distribution, most of the species appeared to be cosmopolitan
in the Indian waters. Hydromedusae are important in the sense that they are
exclusively carnivores and moreover, they are predators and hence they compete
with other predators like fish larvae (Santhakumari and
Nair, 1999). This group often serves as an index to industrial pollution
(Santhakumari et al., 1999). Among the group
hydromedusae, Liriope tetraphylla occupied the dominant position and
more in summer. The similar observations were noticed by Zakaria
(2004), the density of hydromedusae was high in the inshore waters during
summer and in the east coast of India by Santhakumari and
Nair (1999). In the group of scyphomedusae, minimum species were got and
those were picked by hand, because they are maximum in size when compare to
that of the other gelatinous zooplankton and the samples are collected from
the shorewards and some larvae stages were also noticed from the present collection
from the sampling areas. Suchman and Brodeur (2005)
observed that the genus Chrysaora was always most dense at the most shoreward.
The cosmopolitan scyphomedusa Aurelia aurita is particularly abundant
during summer and it is recognized as an important predator in plankton communities
(Hay et al., 1990). In the present investigation
the Aurelia sp. were observed as dominant during the summer. The same
report has pointed out that scyphomedusae A. aurita was the most
abundant and commonly occurred during the summer months (Ballard
and Myers, 2000). Siphonophora are abundant in the Indian seas and constitute
an important part of the marine plankton (Venkataraman,
2005). The dominant species from siphonophores are the Lensia species.
In contrast to just one predominantly epipelagic species, Solmundella bitentaculata,
these high abundances observed in the upper 100 m were mostly due to large numbers
of Lensia sp. (Hosia et al., 2008). In
the present investigation, the Solmundella bitentaculata were present
from the sample collected from seven stations and (Zakaria,
2004), observed that the siphonophore density was high in summer and in
the present observation also the average density in summer was high, among this
the Lensia sp. were observed as dominant in both the seasons. Comb jellies
comprise a diverse phylum (ctenophore) of delicate, gelatinous species living
throughout the worlds oceans (Purcell et al.,
2001). The phylum Ctenophora (known as comb jellies) consists of gelatinous
marine carnivores found from the surface to several thousand meters depth. Ctenophores
are exclusively carnivorous, their principal feeding task is the capture of
prey; there are no herbivorous ctenophores and only one genus can sometimes
be parasitic (Haddock, 2007). Ctenophores have been
known to occur throughout the year along the east coast of India. Pleurobrachia
sp. occurred during the summer and reached a maximum density (Ballard
and Myers, 2000). In the present study also state the same as above and
only one species of Pleurobrachia sp. were identified from this group.
Tunicates were subdivided into two groups: appendicularians encompassing fritillarians
and oikopleurids and thaliaceans which included both doliolids and salps, salps
being numerically dominant (Stemmann et al., 2008).
Salpa fusiformis is usually the predominant gelatinous organism in the
group of salps, Occurrence of high density of the alternation of generation
of Salpa fusiformis in this study suggested that the animals could attain
rapid population increase through the ontogenic cycle (Chae
et al., 2008). This species has the widest world distribution of
all salps (Pages et al., 2001). In the present
study the Salpa fusiformis was also dominantly represented from this
group. The blooming also has been usually observed during spring and summer
when the phytoplankton is productive (Harris et al.,
1991; Menard et al., 1994). Generation of
salps may be achieved when enough food sources are provided to these animals
and the growth rates are extremely high (Laval, 1997).
They can utilize a broad prey size spectrum and are therefore assumed to be
of special importance in oligotrophic environments as the most competitive metazooplankton
group to survive and live at low food concentrations (Fenaux
et al., 1998; Acuna, 2001). Larvaceans can
contribute significantly to planktonic biomass (Clarke and
Roff, 1990; Uye and Ichino, 1995; Hopcroft
et al., 1998) but because they rarely dominate numerically, they
are generally believed to be minor components of the zooplankton community (Hopcroft
et al., 1998). It is interesting to note that the genus Oikopleura
which contains the heaviest species showed significant relationships to both
small phytoplankton and Larvacean biomass (Hopcroft et
al., 1998). In the present study the Oikopleura species were
present throughout the collection and the summer distribution is higher than
in the winter, the same report were noticed by Santhanam
and Perumal (2003). The abundance and community structure of chaetognaths
in the northern Indian Ocean was investigated based on zooplankton samples (Nair
et al., 2002). Sagitta enflata or Flacisagitta enflata,
is a cosmopolitan species in temperate and warm waters and occurs mainly in
the upper 300 m (Pierrot-Bults and Nair, 1991). It is
the dominant chaetognatha species by number in the Indian Ocean (Andreu
et al., 1989; Michel, 1995). In the present
investigation the most dominant species in the chaetognatha is the Sagitta
enflata as in the case of earlier studies.
There was significant variation in atmospheric temperature, water temperature, salinity, pH and dissolved oxygen between different sampling stations during summer and winter (p<0.05). A total of eight groups of gelatinous zooplankton were observed during the present study. They are hydromedusae, scyphomedusae, siphonophores, ctenophores, salps and doliolids, appendicularians and chaetognaths in both the seasons. However, the composition of different species in each group varied from all the stations and seasons. The present study found that the diversity and abundance of the gelatinous zooplankton are highly influenced by the various physicochemical parameters prevailing in the study area. There was positive correlation between the abundance of gelatinous zooplankton and salinity, temperature and pH of the study area, whereas there were a negative correlation between dissolved oxygen and abundance of gelatinous zooplankton.
Authors would like to thank the funding agency of the project from the Ministry of Earth Science and the Director, Faculty of Science, Annamalai University, Parangipettai, for the facility given throughout the study period.
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