DIVERSITY OF ROTIFERS IN THE LAKES OF MYSORE CITY *Padmanabha B Associate Professor of Zoology, Maharani s Science College for Women, Mysore 570005 *padmanabhavb@yahoo.co.in ABSTRACT The diversity study of rotifers carried out for three years (2006-2009) in the three lakes (Kamana, Mandakally and Devanoor lakes) of Mysore city. Totally sixteen species of rotifers were documented, out of which 10 sps belong to genus Branchionus, 3 sps to genus Keratella. 2 sps to genus Filinia and 1 sp to genus Plationus. Kamana lake recorded highest no. of species (12) and lowest abundance (356/L) whereas Devanoor lake documented lowest no. of species (6) and highest abundane (720/L). As diversity decreases, the dominance of rotifers increases in the lakes of Mysore city. Key words: Rotifers, Diversity, Brachionus, Plationus, Keratella, Filinia. INTRODUCTION The rotifers (commonly called wheel animals) are one of the zooplankter belong to phylum Rotifera. These are microscopic, psuedocoelomate, have a length around 0.1 0.5 mm. These are numerically abundant in fresh water, also in brackish and marine habitats. Among zooplankton rotifers are next in abundance to copepods. These have a short lifespan of <14 days. Females are more common than males. In most of the species males are unknown, if known they live for few hours to three days. A number of studies have identified cladoceran and rotiferan species as best indicators of different kinds of aquatic pollution (Mahajan, 1981; Kolkwitz and Marsson, 1902 & 1909). These can be easily identified by their anterior ciliated wheel organ called corona. A rotifer has a transparent cylinder shaped, covered by a thin cuticle. In most of these cuticle thickens to form lorica. Lorica has a arched dorsal plate and a flat ventral plate connected by a flexible cuticular membrane, the sulci. The body is divided in to head, trunk and foot. Head contains corona, mouth and sensory organs. Corona is a ciliary organ, which has anterior (trochus) and posterior lines of cilia (cingulam). Trunk forms major part and encloses organs of digestion, excretion and reproduction. Foot and toes are at the posterior region of the body, which can withdrawn in to the body and useful in locomotion and attachment. The pharynx contains the masticating apparatus called mastax, which contains trophi. Taxonomically important characters are Lorica, its presence or absence, shape, size, spines, sulci, corona, its shape, structure, ciliation, location and type of the mouth, foot, its presence or absence, shape, structure and type of trophi etc., Several taxonomists (Hudson, 1884; Harring, 1913; Hyman, 1951; Pennak, 1953; Edmondson, 1959; Nogrady, 1982; Battish, 1992) proposed different types of classification. But in the present work the classification of Sugumaran et al., (2004) has been adopted, which is the latest and simplest. The phylum rotifera can be broadly divided in to two classes, the Digononta and Monogononta. Members of 22 nd -24 th December 2010 Page 1
Digononta has a pair of ovaries and do not posses any lorica. There are two orders in this class, Bdelloidea and Seisonidea. The Bdelloids have very well developed corona, reproduction is through parthenogenesis, highly contractile body and move over the substratum. The order Seisonidea consists of one genus Seison and two species. These rotifers are epizoic on the gills of Leptostracan crustacean, Nabelia. The corona is reduced and not used for food gathering and locomotion. Class Monogononta comprises majority of known species of rotifers, these are benthic or free swimming or sessile forms. Lorica may be present or absent. Female possessing single ovary with a vitellarium, trophi other than ramate, males are structurally reduced and are present only for few days or weeks in a year. The class Monogononta comprises three orders namely Ploimida, Flosulariaceae and Colothecaceae. Ploimida comprises free swimming and never fixed; foot, when present, with toes. In Flosulariaceae and Colothecaceae adults are sessile but rarely swimming; foot, when present without toes. In Flosulariaceae Mastax or trophi is malleoramate type, whereas in the Colothecaceae mastax is uncinate type. Branchionidae family comprising four genus Brachionus, Keratella, Filinia and Plationus are recorded from the lakes of Mysore city. Several Indian species of rotifers documented by Sharma and Michael (1980). From Mysore few reports are available about the diversity of rotifers (Padmanabha and Belagali, 2006a & b, 2007), but still more precise studies are needed for the authentic documentation about the population dynamics and periodicity of rotifers. In this paper an attempt is being carried out to document the diversity of rotifers in the lakes of Mysore city. MATERIALS AND METHODS Three lakes namely Kamana, Mandakally and Devanoor lakes are selected for this study. The zooplankton samples are collected using plankton net (30 centimeter diameter) made up of 50-micrometer mesh size bolten silk. For qualitative study, zooplankton samples were collected by towing plankton net horizontally at a depth of 40 centimeter for about 10 minutes (Sugumaran et al., 2004). For quantitative study, seventy liters of water samples were filtered through plankton net to obtain 50 ml of concentrated samples (Sarkar and Choudhury, 1992) and enumerated with the help of Sedgwick rafter cell. The zooplankton samples were preserved in 5% formaldehyde and identified with the help of standard keys (Battish, 1992; Dhanapathi, 2000 and Sugumaran et al., 2004) RESULTS AND DISCUSSION Total 16 species of rotifers recorded from the three lakes of Mysore city (Table 1). These 16 sps of rotifers are belonging to four genus Brachionus, Keratella, Filina and Plationus. These genus belong to family Brachionidae & Filinidae and class Monogononta. Taxonomic features of documented rotifera are given below Phylum: Rotifera Class: Monogononta Order: Ploimida A. Family: Brachionidae I. Genus : Brachionus 22 nd -24 th December 2010 Page 2
1. Brachionus forficula (Wierzejski 1891) Length of lorica : 90-120µ Width of lorica : 91-130µ Length of anterolateral spine : 31-41µ Length of antermedian spine : 10-12µ Length of posterior spine : 60-155µ Description: Lorica with four occipital spines, anterolaterals always longer than anteromedian spines. Lorica terminates poteriorly in to two stout, long and sub square spines, basally wide separated and tapering to blunt points, geniculate swellings present at bases of posterior spines. Usually one egg attached in between base of posterior spines. 2. Brachious calyciflorus (Pallas, 1776) Lorica is flexible, smooth and oval. Anterior dorsal margin with four broad based spines. Anteromedian spines longer than anterolateral spines. Posterior spines may be present or absent. This species has many polymorphic forms. Length of lorica : 218-225 µ Widh of lorica : 180-200 µ Length of anteromedian spine : 65-90 µ Length of anterolateral spine : 46-71 µ Length of posterior spine : 0-162 µ Description: Anterior dorsal margin of the lorica with broad based stout spines. Posterior spines are present. 3. Brachionus falcatus (Zacharias, 1989) Length of lorica : 122-155µ Width of lorica : 126-175µ Length of anteromedian spine : 11-22µ Length of anterolateral spine : 10-315µ Length of intermediate Spine : 90-120µ Length of posterior spine : 148-170µ Dscription: Anterior dorsal margin of lorica with six unequal spines, the intermediate spines long and curved. Median spines are smaller than lateral spines. There are two very long, at base widely separated, bent inwards posterior spines are present. 4. Brachionus quadridentatus (Hermann, 1783) Length of lorica : 115-118 µ Width of lorica : 120-130 µ Length of anterolateral spine : 20-45 µ 22 nd -24 th December 2010 Page 3
Length of intermediate spine : 8-15 µ Length of anteromedian spine : 40-92 µ Length of posterolateral spine : 0-148 µ Description: Lorica broader than long, with six occipital spines of which the medians are long and curved outward. Two posterior spines present. 5. Brachionus caudatus (Ahlastrom, 1940) Length of lorica : 91-155 µ Width of lorica : 78-152 µ Length of anterolateral spine : 10-25 µ Length of anteromedian spine : 13-16 µ Length of posterolateral spine : 25-45 µ Description: Lorica with six occipital spines, the lateral longer than the medians, intermediate spine reduced. Posterior spines long. 6. Brachionus diversicornis (Daday 1883) Length of lorica : 220-228 µ Width of lorica : 18-190 µ Width of lorica near posterior : 75-80 µ Length of anterolateral spine : 110-115µ Length of anteromedian spine : 19-22 µ Length of right posterior spine : 117-120 µ Length of left posterior spine : 30-50µ Description: Lorica elongate with four occipital spines, of which the laterals longer than medians. Right posterior spine longer than the left. Foot long and toes with characteristic claws. 7. Brachionus plicatilis (Muller, 1786) Length of lorica : 23-240 µ Width of lorica : 213-220 µ Length of anterolateral spine : 20-24 µ Length of anteromedian spine : 16-18 µ Description: Lorica is oval, narrows anteriorly, Anterodorsal margin with six broad based pointed spines, all are almost equal in length. 8. Brachionus angularis (Gosse, 1851) Length of lorica : 80-89µ Width of lorica : 76-83 µ Length of lateral spine : obliterated Length of intermediate spine : obliterated Length of median spine : flanking V shaped notch 22 nd -24 th December 2010 Page 4
Length of posterior spine : wanting Description: Lorica stippled, divided in to dorsal and ventral plates. Anterodorsal margin with two median spines flanking a V shaped notch. Lateral and intermediate spines usually obliterated. Posterior spines wanting. 9. Brachionus rubens (Ehrenberg, 1838) Length of lorica : 146-150µ Width of lorica : 100-108µ Length of lateral spine : 0-10µ Length of intermediate spine : 2-5µ Length of median spine : 30-32µ Description: Lorica firm, oval, smooth, dorsoventrally flattened, composed dorsal and ventral plates., anterior dorsal margin with six spines, medians longest, intermediates longer than laterals. Medians and intermediates with peculiar asymmetric shape (saw-toothed), posterior spines absent; foot opening subsquare and small. 10. Brachionus bidentata (Anderson, 1889) Length of lorica : 121-155µ Width of lorica : 120-129 µ Length of anterolateral spine : 28-30 µ Length of anteromedian spine : 27-32µ Length of anterointermediate spine : 11-15µ Length of posterior spine : 14-19µ Description: Lorica firm, stippled, with defnete pattern of plaques divided in to dorsal, ventral and basal plates. The dorsal and ventral plates soldered together for three-fifth (3/5) of the lorica and thereafter united to a third basal plate.; dorsal margin with six spines; lateral always longer than medians, medians longer than intermediates, posterior spines may be vary in length and position of origin but may be absent; foot opening with foot sheath. II.Genus : Plationus 11. Plationus patulus (Segers et al., 1993) Length of lorica : 130-135 µ Width of lorica : 125-150140 µ Length of anterolateral spine : 28-30 µ Length of occipital intermediate Spine : 32 µ Length of Occipital median Spine : 58 µ Length of posterolateral spine : 22 µ Length of posterior spine : 28-31 µ 22 nd -24 th December 2010 Page 5
Description: Occipital margin with six spines of which medians slightly longer than the outer. Ventral margin with four spines. Posterior lateral spines are longer than the median. III.Genus : Keratella 12. Keratella tropica (Apstein, 1907) Length of lorica : 82-85 µ Width of lorica : 63-65 µ Length of anterolateral spine : 13-16 µ Length of intermediate spine : 17-20 µ Length of anteromedian spine : 23-25 µ Length of right posterior spine : 95-98 µ Length of left posterior spine : 19-22 µ Description: Anterodorsal margin of lorica has six spines. Median spines curved and longest. Intermediate spines are shortest. Posterior end has two unequal spines. The right posterior spine is longer than left posterior spine. Three hexagonal plaques are present on dorsal plate of lorica. A small four sided plaque is present between the posterior border of lorica and the last hexagonal plaque. 13. Keratella quadrata (Muller, 1786) Length of lorica : 084-115 µ Width of lorica : 63-93 µ Length of lateral spine : 15-43 µ Length of intermediate spine : 20-28 µ Length of median spine : 24-35 µ Length of posterior spine : 80-85 µ Description: Anterior margin of lorica with six spines, medians longest and curved ventrally, laterals shortest. Posterior spines almost equal. Dorsal plate of lorica with three median plaques and one pentagon terminates in to a short median line. 14. Keratella cochlearis (Gosse, 1851) Length of lorica : 286-290 µ Width of lorica : 247-250 µ Length of lateral spine : 97-100 µ Length of intermediate spine : 20-32 µ Length of median spine : 24-28µ Length of posterior spine : 128-130 µ Description: Anterior margin of lorica with six spines, medians longest and curved ventrally, laterals shortest. Posterior spines strong, median & single. Dorsal plate of lorica with three median plaques and one pentagon terminates in to a short median line. 22 nd -24 th December 2010 Page 6
Order: Flosculariacea B. Family: Filinidae iv.genus : Filinia 15. Filinia terminalis (Plate, 1886) Length of retracted lorica : 100-102µ Width of retracted lorica : 48-50 µ Length of anterior spine : 345-350 µ Length of posterior spine : 257-260 µ Description: Lorica thin, flexible and barrel shaped when contracted. Two anterolateral spine equal in length; with one terminal posterior spine. 16. Filinia longiseta (Ehrenberg 1834) Length of retracted body : 178-180 µ Width of retracted body : 118-120 µ Length of anterior spine : 247-250 µ Length of posterior spine : 380-400 µ Description: Lorica with two equal anterior spines and one posterior spine. Posterior spine is longer than anterior spine. Total 16 species of rotifers are recorded during this study period (2006-2009) form the lakes of Mysore city. Out of which, Brachionus forficula, Brachionus calyciflorus, Brachionus falcatus, Brachionus quadridentatus, Brachionus caudatus, Brachionus diversicornis, Brachionus plicatilis, Brachionus angularis, Brachionus rubens and Brachionus bidentata (10 species) belong to genus Brachionus. Brachionus is by far the best known genus from India. Keratella tropica, Keratella procurva and Keratella cochlearis (3 species) belong to genus Keratella, Plationus patulus (1 species) belong to genus Plationus. These three genuses (Brachinous, Keratella and Plationus) belong to Family Brachionidae. The members of Brachionidae family are dorsoventrally flattened, heavy loricated planktonic forms.these carrying variable number of spines on the anterolateral margin. The posterior margin may or may not have spines. The lorica may be made up of single or two plates. This Brachionidae family belongs to Ploimida order. Filinia longiseta and Filinia terminalis belong to genus filinia, family Filinidae, order Flosculariacea. Ploimida and Flosculariacea orders belong to class Monogononta of Phylum Rotifera. Members of Monogononta form the great majority of known species, which are benthic, free swimming and sessile forms. Lorica may be present or absent. Females possessing single ovary with vitellarium. 22 nd -24 th December 2010 Page 7
Highest number of species (12) and lowest abundance (356/l) of rotifers documented in the Kamana lake, whereas lowest number of specie (6) and highest abundance recorded in the Devanoor lake (720/l). As diversity decreases the abundance of rotifers increases in the lakes of Mysore city (Table 1). ROTIFERS- PHOTOGRAPHS 1. Brachionus forficula 2. Brachionus calyciflorus 3.Brachionus falcatus 4. Brachionus quadridentatus 5. Brachionus caudatus 6. Brachionus diversicornis 22 nd -24 th December 2010 Page 8
7. Brachionus plicatilis 8. Brachionus angularis 9. Brachionus rubens 10. Brachionus bidentata 11. Plationus patulus 12. Keratella tropica 13. Keratella quadrata 14. Keratella cochlearis 15. Filinia longiseta 22 nd -24 th December 2010 Page 9
16. Filinia terminalis REFERENCES 1. Battish S.K. 1992. Fresh water zooplankton of India. Oxford and IBH Publ. Co. Pvt. Ltd. Pp. 69-114. 2. Dhanapathi M.V.S.S.S. 2000. Taxonomic notes on rotifers from India. IAAB Publ. Hyderabad. Pp.12-168. 3. Edmondson W.T. 1959. Rotifera. In: Freshwater Biology. 2 nd edn,(edr, W.T. Edmondson). John Wiley & sons New York. Pp. 420-494. 4. Harring, H.K. 1913. Synopsis of the Rotatoria. Bull.U.S. Nat.Mus., 81:1-226. 5. Hudson, C.T. 1884. An attempt to re-classify the rotifers. Quat.Journ.Micro.Sci., 24:335-356. 6. Hyman, L. H. 1951. The Invertbrates, Vol. III. Acanthocephala, Aschlemminthes and entoprocta. McGraw Hill, New york,pp. 572. 7. Kolkwitz R. and Marsson M. 1902. Gundasatze fur die biologische Beurteilung des Wassers nach seiner Flora and Fauna. Mitt. Prufungsanst. Wasseversorg. Abwasserbeseit.1, 33-72 8. Kolkwitz R. and Marsson M. 1909. Okologie der tierischen saprobian. Int. Revue ges. Hydrobiol, 2, 126-152 9. Nogrady, T. 1982. Rotifera. In: Synopsis and classification living organisms, Vol. I. (S.P. Parker, ed in chief). McGraw Hill Book Co., New York, pp. 865-872. 10. Mahajan C.L. 1981. Zooplankton as indicators for assessment of water pollution. WHO workshop on biological indicators. Cent. Bd. Prev. Cont. Poll. Osmania University. Hyderabad. Pp.135-148. 11. Padmanabha B and Belagali S.L. 2006 (a). Effects of heavy metals on rotifers in the lakes of Mysore- A model approach. Res. J. Chem. Environ. 10(1), 48 50. 12. Padmanabha B and Belagali S.L. 2006 (b). Comparative study on population dynamics of rotifers and water quality index in the lakes of Mysore. Nat. Env. Poll. Tech., 5(1), 107 109. 13. Padmanabha B. and Belagali S.L. 2007. Diversity indices of rotifers for the assessment of pollution in the lakes of Mysore city, India. Poll. Res., 26(1), 65-68. 14. Pennak R.W. 1953. Freshwater invertebrates of the United States. Ronald press Co. New York. Pp. 769. 15.Sarkar S.K. and Choudhary B.P. 1992. Role of some environmental factors on the fluctuation of plankton in a lentic pond at Calcutta. In: Limnological research in India. Pp.108-132. 16. Sharma, B. K. and Michael, R.G. 1980. Synopsis of taxonomic studies on Indian Rotatoria. Hydrobiologia, 73: 229-236. 22 nd -24 th December 2010 Page 10
17. Sugumaran J., Naveed S.M. and Altaff K. 2004. Rotifers. In: A manual of zooplankton for national workshop on zooplankton (Edr. Altaff, K.) Chennai, India. Pp. 19-39. Table 1: Diversity and abundance of Rotifers (Avrg.No./L) in the lentic ecosystems of Mysore (2006-09). Sl.No species Kamana lake (12) Mandakally lake (9) Devanoor lake (6) 1 Brachionus forficula 79 100 189 2 Brachionus calyciflorus 67 130 192 3 Brachionus falcatus 42 - - 4 Brachionus quadridentatus 10 - - 5 Brachionus caudatus 15 138 252 6 Brachionus diversicornis 16 - - 7 Brachionus plicatilis 30 - - 8 Brachionus angularis 18 - - 9 Brachionus rubens 22 18-10 Brachionus bidentata 16 20 46 11 Plationus patulus 12 15 18 12 Keratella tropica 15 23-13 Keratella procurva 14 -- - 14 Keratella cochlearis - 22-15 Filinia longiseta - 08 23 16 Filinia terminalis - - - Total 356 474 720 22 nd -24 th December 2010 Page 11