J. mar. biol. Ass. , 19%, 38 (1 & 2) : 25 - 33

DESTRUCTION OF TIMBER STRUCTURES IN THE ESTUARINE SYSTEMS OF THE SOUTR WEST COAST OF INDIA, THE KALLAYI AND BACKWATERS

N. BALAKRISHNANNAIR Department of Aquatic Biology and Fisheries, University of , Trivandrum, 695 007.

ABSTRACT

The nature. of destruction of timber structures in the Kallayi and Beypore backwaters of'the South-West mast of India has been examined. Five species of shipworms namely Dicyathifet manni, Lyroduspedicellatus, Teredo furcifera, Nausitora hedleyi and Banhia carinata, two species of pholads Martesin striata, Martesia (Pam'coma) nairi and three species and a variety of sphaeromatids Sphaeroma terebrans, S. annandalei, S. a. travancorensis and S. walkeri constituted the boring community. The incidence, and relative abundance of these borers in relation to the salinity profile of the estuary have been reported.

where large quantities of wood are exposed to their attack. The present paper describes the nature of distribution of wood borers in two TIMBERis extensively used all along our backwater systems of Kerala. coastal zone for harbour structures, waterfront installations, different types of fishing crafts and aquaculture implements. Mangrove forests fringe the shore line, more especially the Collections wCre camed out of sheltered areas and are exposed to wood-boring organisms from Kallayi and submergence and emergence during the tidal Beypore backwater systems during the cycles. All these are subject to the attack of pre-monsoon period February-May of 1988. timber boring organisms. The total damage The availability of infested wooden samples inflicted is indeed great, but very difficult to and the area of the system from the bar-mouth assess, yet it is estimated that in India, the to the upper reaches were taken into fishing industry alone suffers an annual loss consideration while selecting sampling sites. of nearly 96 million rupees owing to the Five representative sites in Kallayi covering an ravages on wooden fishing implements by area of 4 krn and 10 sites in Beypore covering these pests (Qasim, 1988). a distance of 7 km from the bar-mouth to the upper reaches were selected for the study. The While a large volume of information is infested samples of wood (chiefly the stem of available on the different aspects of the Cocos nltcifera) were first preserved in neutral taxonomy and biology of these pests (Nair, 5% formalin, packed in polythene bags and at 1984, 1988, 1994) our information is still the laboratory, a fixed volume (1000cc of wood incomplete regarding the incidence and relative measured by displacement volume of water) of abundance of these in the estuarine systems the sample, cleaned of surface fouling, was 26 N. BAJAKRISHNAN NAIR

examined for the relative abundance of different for retting. This along with the logs kept in species of borers. The total number of bore-holes the water for conditioning all through the year of the respective species was checked, counted foul the water considerably. The tidal currents and recorded. Then, the samples were dissected enter upstream into the river up to about 18 to remove the borers. Besides salinity, related to 20 km and hence the water is saline during parameters such as temperature, pH and oxygen most of the months. content of water have also been recorded using THE BEYPOREESTUARY (Fig. 2) standard procedures (Martin, 1970). The is one of the major rivers THEKAUAn BACKWATERSYSTEM (Fig. 1) of the West Coast of India and joins the The is connected with the Arabian sea at Beypore near Calicut. At its Chaliyar on the south by a man-made canal. Iower reaches it is known as the Beypore river forming the Beypore backwater before if joins the sea. The Beypore estuary enters the sea in a ~~~th-we~t&l~direction. There is a horse-shoe shapped bar at the entrance and the depths over it vary from 1.5 m to 1.9 m. The sea bed slope at Beypore, is comparatively flat

FIG. 1. Map of Kallayi Backwater system The river passes through Olavanna, Manava and Kallayi before finally joining the sea near FIG.2. Map of Baypore estuary Calicut. This backwater is tidal in character and divides the Calicut town into two before with a 9m contour at a distance of 3.5 km its confluence with the sea. The world's second from the river mouth. The tides at Beypore biggest timber depot and a large number of are semidiurnal with a period of 12 hours and wood-based industries are also situated along 40 minutes. The maximum flows occur during its banks. The entire stretch is shallow. the months of June-August, and during this Considerable amount of coconut husks are period the tidal limits come down to the fisheries deposited in this estuary by coir industry units wharf downstream of the Feroke bridge for a DESTRUCTION OF TIMBER STRUCTURES IN THE ESTUARINE SYSTEMS 27 ,

river discharge of 500 m3/sec. The least causing severe damage to the water quality and discharge is found to occur during the latter fishery prospects of the estuary. The Beypore half of April and first half of May, during backwater is connected to Kallayi river and which period the tidal limit is observed to be large quantities of timber are floated down to at a distance of 26 km upstream of the mouth Kallayi through the Beypore river from the near the confluence of the two major tributaries valley. This part of the backwater is joining the estuary. an important link of the westcoast inland navigation system. KALLAYI @ HYDROGRAPHY RESULTS AND DISCUSSION The results of the study conducted at Kallayi are presented in Table 1 and fig. 3. and those of Beypore in Table I1 .and Fig. 4. The most notable features of the study ate - SALINITY indicated below.

BEVPORE =r

- ATMOSPHERIC 0-4 WATER C1 SEDIMENT 30

@ WOOD-BORING ORGANISMS

-03 0,C

L 0 SHIPWORMS a0 PHMADS

m sPH,aERoMATIos

FIG. 3. Hydrography and distribution of wood borers in Kallayi backwater Beypore estuary has been subjected to severe pollution due to the effluent discharge FIG.4. Hydrography and distribution of wood borers from the Mavoor Gwalior Rayons Factory in the Beypore estuary 3 28 N. BALAKRISHNAN NAIR

At Kallayi, the atmospheric temperature the value of this parameter was negligible. The fluctuated between 31 - 33°C. The minimum values ranged between 33.2 x 1u3 - 33.8 x values of atmospheric (31°C) and water (30.5"C) The distribution of salinity in the different

TABLE1 Abundance of wood-boring organisms in ';~eKallayi estuary during pre-monsoon period (No. of organisms/1000 cc of wood) - 1 2 3 4 5 Total SHIPWORMS D. mnnni 5 10 4 9 10 38 (8.3) (34.50) (3.7; (40.9) (47.6) (15.8)

L. pedicellntus 41 6 7 4 5 3 134 (68.3) (2O.7) (73.2) (z2.7) (14.3) (55.8) T. furcfirn 11 13 23 8 8 63 (18.3) (44.8) (21.3) (46.4) (38.1) (26.3) B. cnrinntn 3 - 2 - 5 (5.0) (1.9) (2.1) Total 60 29 108 22 21 240 (17.0) (9.9) (36.4) (4e4) (28.0) (15.8) PHOLADS M. strinta 17 13 - 1- 4 12 63 (25.0) 43.3 (25 .O) (3.8) (22.2) (19.4) M. (P.) nniri 5 1 17 -51 101 42 262 (75.0) (56.7) (75.0) (96.2) (77.7) (80.6) Total 68 30 68 105 54 325 (19.3) (10.2) (22.9) (20.9) (72.0) (21.4) SPHAEROMATIDS S. terebrnns - 130 55 47 - 222 (55.3) (45.5) (12.5) (24.2) S. anr ,uidnlei 225 105 66 329 - 725

(100) (44.7) (54.6) (87.5) + (75.8) Total 225 235 121 376 - 957 (63.7) (79.9) (40.7) (74.8) (62.9) Grand Total 353 294 297 503 75 1522 Species of borers in parenthesis; *Percentage of groups temperatures were noted at station 1 and the regions of the estuary from the bar mouth to maximum values 33°C (atmosphere), 335°C the rivenne zone of the estuary at station 5 (water) at station 5. At Beypore, atmospheric was rather homogeneous. temperature varied between 30.5 to 33°C with Permanently connected to the adjoining the minimum at station 1 and the maximum sea, the Beypore estuary is influenced by tidal at station 6, 7 and 10. Surface water temperature currents, the limit of which is observed at a fluctuation had a range of 1.5"C, the maximum distance of about 28 km upstream of the mouth of 33.5"C was recorded at stations 7 and 8 during the summer months o'f April and May and the minimum of 32°C at station 1. when the river discharge is the lowest (James The salinity maintained high values at all et al. 1983). The minimum salinity of 18.8 the study sites in Kallayi. The difference in x lo9 was recorded in the interior of the DESTRUCTION OF TIMBER STRUCTURES IN THE ESTUARINE SYSTEMS 29

h h hh '9 a oq h Ah- 1 -2 4% 1 -2 a~ 9: 1 VW VW ww wwz

hcn h" n hhh I 2 I modrr) ;;g" rnZ 2z "'4 I I I I s ww www

h G - hhh I s2rg I 26 a$ -2 39.::; I I I I rr) o?) w VW WWV-

h h "! h hhh I =, wN I 3: gz hzrr) 09 1 gF9z 1 I VW w"z%g -I% 30 N. BALAKRISHNAN NAIR

estuary at station 5 while the maximum of average concentration of 6.5 mlA was noticed 34.4 x 10'~was noted at station 10 near the whereas in the middle and riverine zones the bar mouth region. At the other stations, the values remained at 5.9 mlA and 5.5 mlfl values fluctuated within these two extremes. respectively. Based 011 the differences in the surface water Wood-boring organisms salinity, the estuary can be divided into three regions, namely, the bar mouth region At Kallayi four species of shipworms comprising the stations 1,2,9 and 10, the middle (D. maru~i,L. pedicellatus, T. Jilrcifera and B. region incorporating the stations 3, 7 and 8, carinata), two species of pholads (Martesin and the riverille zone including the - stations striata and Martesia (P.) nairi) and two species 4-6. The average values of salinity in these of sphaeromatids (S. terebram and S. regions showed a decreasing trend from the arrnartdalei) formed the boring community. Of bar mouth (30.2 x through the middle the three groups of borers, sphaeromatids (25.5 x to the riverine zone (21.3 x predominated comprising 62.90% of the total of the estuary. population followed by 'pholads (21.4%) and shipworms (15.8%). The values of pH varied between 6.8 and 7.0 at Kallayi. The minilnuin and maximum The incideilce and relative abundance of were noted at the adjacent stations 2 and 3 these boring organisms in the different stations respectivley. At Beypore, pH fluctuations were were noteworthy. Shipworms, for instance, between 6.6 and 7.4; the maxiinurn being' recorded a high percentage of incidence (36.4) recorded at station 10 and the minimum at at station 3 and the lowest (4.4) at the adjacent station 8. station 4. The incidence of shipworms at stations 1 (17.0) and 2 (9.9) at the mouth region of Unlike salinity, a wide range of variation the estuary was much lower than that of the in the content of dissolved oxygen was noticed riverine zone at station 5 (28%). A more or at Kallayi. In the first 3 stations the less similar pattern of occurrence was noticed concentration of oxygen was low. The minimuin for pholads which recorded the maximum value value of 1.5 mlll was noted at station 1. But (72%) at station 5 and minimum (10.2%) at in the adjacent stations 4 and 5 considerable station 2 near the bar mouth. Moderate values increase in values were noticed with 7.1 mlll of incidence of pholads was noted at the stations and 6.2 mlA respectively towards the riverine 3 and 4 of the middle region of the estuary. zone of the estuary. The observed depletion of Sphaeromatids, on the contrary recorded a high oxygen in the system was primarily due to percentage of incidence at stations near the bar pollution resulting from the conditioning of mouth and middle region of the estuary. The large quantities of timber kept in water in the peak occurrence (79.9%) of Sphaeroinatids was lower reaches of the river basin covering stations noticed at station 2 where ininiinum values 1-3. were recorded for shipworms (9.9%) and pholads (10.2%). Sphaeromatids were not The dissolved oxygen content at Beypore obtained from station 5. varied from 7.3 mlA (station 10) to the lowest value of 5.2 inln (station 4). At most of the Apart from the above, the individual stations, moderate values were recorded for this species of the different groups of borers were parameter. Regionally the values did. not show also found to exhibit marked differences in much difference. In the bar mouth region an abundance and distribution within the stations DESTRUCTION OF TIMBER STRUCTURES IN THE ESTUARINE SYSTEMS 31

in the different regions of the estuary. Of the of S. annandalei was noticed at stations 1 four species of shipworms, L. pedicellatus (100%) and 4 (87.50%). The minimum formed 55.8% of the total group. The other percentage occurrence was noted at station 2 species T. furcifera, D. manni and B. carinata (44.68). This species was not obtained from shared the rest of the ship-worm population station 5 in the riverine zone of the estuary. and the percentages were 26.3, 15.8 and 2.1 S. terebrans was seen only in 3 stations near respectively. Among the 5 representative the mouth and middle regions. Among the three stations L. pedicellants recorded high values at stations the highest (55.32) and lowest (12.50) station 1 (68.3) and 3 (73.2) and the lowest values were observed at stations 2 and 4 at station 5 (14.3). On the other hand, T. respectively. The incidence of this species at furcqera registered maximum occurrence at station 3 (45.45) was moderate. stations 2 (&.8%), 4 (36.4%) and .5 (38.1%) The wood-boring community at Beypore where the incidence of L. pedicellattts remained low. D. manlii was more prevalent at station was composed mainly of 4 species of shipworms 5 in the riverine zone than in the other regions (D. mamti, L. pedicellatr~s, f jifrtrcifera and N. Izedlej1i), 2 species of pholads (M. striata and of the estuary. Comparatively low values of M (P.) nairi. 3 species and one variety of incidence for this species were obtained at sphaeromatids (S. terebrans, S. nmtandalei, S. stations 1 (8.3) and 3 (3.7). Regarding the species B. cari~tataonly a few specimens were annandalei travancorensis and S. walker;). The sphaeromatids formed the bulk of the boring obtained, community (64%) and shipworms stood next A vast majority of the pholad population (22.5%). The pholads formed only 13.5% of was formed by Mnrtesia (P.) rrniri which the total density of boring organisms in the recorded 80.6% in the estuary. The occurrence estuary. of M. striata was very low in the system (19.4%). In all the study sites the percentage Neither the occurrence nor the activity of dominance of M. (P.) nairi remained above 75 these borers in the estuary was unifonn, distinct except at station 2 where the lowest value of differences in the distribution and relative 56.7% was noted. The peak infestation (96.2%) abundance of these animals were noticed in occurred at station 4. The values for M. striatn the different station as well as in the different on the other hand, remained invariably lower regions of the estuary. Among the 10 study than those of M. (P.) nairi at all the stations. sites the maximum activity was noted at station The highest value for M. striata (43.33) was 3 (26.5% and 8 (31.7%) and the least at station noted at station 2 which was lower than, the G (1.5%). But the abundance of individual minimum value recorded for M. (P.) nairi at boring organisms varied widely within and the same station. Similarly the lowest value between stations. (3.8) for M. striata was noted at station 4 where the other species peaked the density. Shipworms were obtained frorn all the study sites in the estuary. Maximum abundance Of the two species of sphaeromatids was noted at station 4 (53.8%)and the minimum recorded from the estuary a predominance of at station 8 (5.20%). Moderate levels were S. anrrandalei was noticed constituting 75.80% recorded at stations 2, 3, 6 and 7. An increasing of the total sphaeromatid population in the trend in shipworm ytivity was apparent from system. The rest of the group was formed by the stations near the bar mouth to those of the S. terebrans (24.2%). The maximum activity middle and riverine zones of the estuary. 32 N. BALAKRISHNAN NAIR

L. pedicellatus was the most destructive dropped to 2.7. A more or less uniform level species comprising 76.9%of the total shipworm of occurrence was noticed for this species in population. Its peak incidence (94.6%) was all the regions of the estuary. The species S. noted, at station 4 and lowest of 15.6% at annundalei was found along with S. terebrans station 1. In the majority of the stations, the and its total incidence in the estuary (3.2) was incidence of this species remained higher than much lower than that recorded for the latter 50, more so in the middle region (65.5%) and species. The maximum percentge density (29.7) riverine zone (62.4%) than in the bar mouth was noted at station 4 and the minimum region (53.1) of the estuary. N. kedleyi stood (0.9) at station 8. A variety of this species next to L. pedicellatus in abundance. It was S. annandalei travarzcorensis was also recorded found active in all the regions of the estuary from the estuary at stations 2 and 10 near the with a total incidence of 10.7. 1ts peak density bar mouth region. The species occurred in large (71.8%) was noted at station 5 in the riverine numbers in these two stations. A few specimens zone of the estuary. D. manni was also present of the marine species of Sphaeroma walkeri in fair numbers. It constituted 9.1%of the total was also obtained from the mouth region of shipworms. It was absent from the riverine the estuary at station 1. The percentage zone and was found more active at the bar occurrence of S. artnandalei travancorensis and mouth region where maximum incidence of S. walkeri in the system was 7.2 and 0.1 59.4 was noted at station 1. The lowest respectively. occurrence (6.1%) of D. maitni was noticed ai station 3. T. furcifera was scarce, comprising Distribution of borers in relation lo salinity only 3.3% in the whole system. It was recorded The Kallayi estuary with its high salinity only from 3 stations and was absent in the rivenne zone. water temperature and normal pH is noteworthy. The oxygen content was low at stations 1, 2 Pholads exhibited minimum incidence in and 3 owing to the proximity to the wood the estuary. A majority of the pholad population based industries, +the floating logs of timber in was formed by Martesis (P.) nairi comprising the area, and the retting of coconut husks. The 89.5% of the total density. The other species correlation of the incidence of borers to the M. strinta shared the rest (10.5%) of the prevailing hydrographic features was not population. The activity of the latter species discernible in this system. was found only at 4 stations and the maximum B. carinata and T. firrcifera are known occurrence (58.1%) was noted at station 7 in the middle region of the estuary..M. (P.) nairi to be sensitive to lower salinities and this is on the other hand, peaked the density with reflected in their occurrence towards the bar extreme values in the majority of the stations mouth. L. pedicellatus and D. maruti are and the lowest value of 41.9% was recorded euryhaline species having the ability to station 7. withstand low oxygen values in the ambient water for fairly long periods. This along with the cyclical tidal flushing would enable them With regard to sphaeromatids, the species to survive in such situations. S. terebrarts contributed as much as 89.6% of the total population. The percentage dominance Unlike in Kallayi the distribution of the of the species remained above 70 at all the boring community was related to the salinity stations except at station 10 where the incidence profile in the Beypore estuary. Stations (1, 2, DESTRUClTON OF TIMBER STRUCTURES IN THE ESTUARINE SYSTEMS 33

8, 9 & 10) near the bar-mouth had salinity pholad exhibited a greater preference for less ranging from 26.3 to 34.4 ppt, stations in the saline areas and for those locations where the middle part (3, 4, 6 & 7) had a range between competition with the related species M. (P.) 21.9 and 25.1 ppt., while station (5) nairi was comparatively less. toward the river side recorded values less than 19 ppt. Thus, this heterogeneous group of wood boring organisms seems to effectively share Species such as D. marirti, T. furcifera their very limited substratum naincly wood in and S. walkeri were thus seen in large numbers the estuary by taking advantage of the salinity in areas near the bar mouth where the salinity profile prevailing in the area, avoiding too was above 26 ppt. Typical euryhaline species much competition. This has considerable such as L. pedicellatlts N. hediqi, M. (P.) survival value in the dynamic biotope. Otlier nairi, S. rerebraits, S. arzizaridalei were parameters such, as temperature, pH and oxygen distributed fairly uniformly throughout the content were within the tolerance limit of the estuary while M. striata the common estuarine different species.

REFERENCES

MA~N,J, 1970 Marine chemishy Vol. 1 Marcel . Chandrakala Hora Memorial Medal Lecture, Proc. Indinti Dekker Inc, NY, U.S.A. Nat. Sci. Acad. B 54 (1) : 7-23. 1994. Biodeterioration of cellulose NAIR,N- B. 1984. problem of marine timber materials in estuarine and insular biotopes. Proc. Ittdinrr destroying organisms along the Indian coasts, Proc. Iltdinn Nat. Sci. Acnd. B. 60 (3) : 217-228. Acnd. Sci. Golden Jubilee (Anim Sci.) 93. (3) : 203-223. QASIM S. Z. 1988. Mnrirte Biodeteriorntion Adtnnced 1988. The problem of biodeterioration Techniques Applicable to Indintt Ocentts. Inaugural Address along the Indian coasts and its impact on fisheries. The Oxford & IBH publishing Co. Pvt. Ud New Delhi XXI-XXV. J. mar. bioL Ass. India, 1996, 38 (1 & 2) : 34 - 39

NEMATODE PARASITES ASSOCIATED WITH THE FLATFISHES (ORDER : PLEURONECTIFORMES) OF THE KERQLA COAST

A. BIJUKUMAR* Department of Aquatic Biology and Fisheries, University of Kerala, Beach P.O., Trivandrum - 695 007, Kerala.

ABSTRACT

Twenty-one species of flatfishes belonging to five families, commonly available in the southwest (Kerala) coast of India, were examined for nematode parasites. Five species of nematodes -Hysterothylacium sp. 1 (larva), Hysterothylacium sp. 2 (larva), H. aduncrrm, Procamallarurs sp. and Philometra lateolabracis were recorded. lbenty out of the twenty-one flatfish species examined harboured one type of nematode parasite or the other. Infection with Hysterothylaciurn. sp.1 larva was more prevalent among flatfishes. Presence of zoonotic nematode Hysterothylacium sp. in about 90 per cent of the flatfish species and in 50 percent of the flatfishes of the Kerala coast demands serious attention from public health authorities. Further, infection with Philometra lateolabracis inflicted severe damages in the ovaries of flatfishes and this warrants further studies. Most of the nematode parasites are recorded for the first time from flatfishes of India.

Hence a survey of the nematode parasites infecting the common flatfish species of Kerala coast and also a study of the nature of nematode NEMATODESare a group of deleterious fish infections were attempted. parasites. In fishes growth retardation, impaired gonad development, extensive muscle destruction The author is grateful to Dr. S. Radha- and/or increase in the cost of processing are krishnan, Dept. of Aquatic Biology & Fisheries, known to be caused by the nematodes. Further, University of Kerala, for his help and advice many nematodes are zoonotic and are very and to Dr. F. Moravec, Institute of Parasitology, injurious to human beings, even causing such Czech Academy of Sciences, for his help in pathological conditions as meningitis (Moller identifying the parasites. Thanks are due to and Anders, 1986). University Grants Commission for providing Junior Research Fellowship, during the tenure of which this work was camed out. Nematode parasites infecting freshwater fishes of India have been studied well (Soota, MATERIAIS AND ~'THODS 1983; Sood, 1988). However, many of the marine fishes still remain to be investigated menty-one flatfishes (order : Pleuro- for nematode parasites, not to speak of the nectiformes) belonging to five families were pathology of nematode parasites infecting examined for nematode parasites. The fishes flatfishes of India. Thus there are no reports selected include: Bothus myriaster (Temminck of nematode infection from flatfishes of India. & Schlegel), Crossorhon bus azureus (Alcock), *Present Address: Lecturer in Zoology, N.S.S. College, Engyprosopon grandisquamis (Temminck & Ottapalam-679 103, Kerala Schlegel), Laeops nigrescens Lloyd, Pseudor- NEMATODE PARASITES ASSOCIATED WITH THE FLATFISHES hombus arsius (Hamilton), P. elevatus Ogilby, Host fishes (except Eltryglossa orientalis) P. javanicus (Bleeker) and P. triocellatus were collected from Neendakara and Vizhinjam (Schneider) belonging to the family. Bothidae, landing centres of the Kerala coast. Euryglossa Cynoglossus arel (Schneider), C. dubius Day, orientalis was collected from Veli Lake and C. lida Pleeker), C. macrostomus Norman and Akathumuri estuary. In the laboratory host fishes C. puncticeps (Richardson) belonging to the were examined for nematode parasites following family Cynoglossidae, Samaris cristatus Gray the methods suggested by Moravec et al. (1992).

TABLE1. List of nematode parasites collected, with their host fish and the site of infection

Parasite Host Location Hysterothylacium Bothus myriaster Intestine, mesentary sp. 1 (larva) Crossorhornbus azureirs Intestine, mesentary Engprmopon grandisqiramis , Intestine, mesentary Laeops nigrescens Intestine, mesentary Pseudorhombus arsius Intestine, mesentary P.eleratus Intestine, mesentary P.javanicus Intestine, mesentary P.triocellntus Intestine, mesentary Cynog/ossus are1 Intestine muscle C.dubius Intestine, mesentary C.lidn Intestine, mesentary C.macrostomris Intestine, mesentary C.puncticeps Intestine, mesentary Samaris cristatus Intestine, mesentary Psettodes erumei Intestine, mesentary Aesopin cornuta Intestine, mesentary Synaptura commersortiarta Intestine, mesentary Z.s~~~taptzrroides Intestine, mesentary Hys&rothylacium Cynoglossus nrel . Ovary sp.2 (larva) Hysterothylncium Crossorhornbus azureus Intestine aduncum Pseudorlzombus javanicus Intestii~e Cynoglossus arel Intestine Samnris cristatus Intestine Zebrins synnpturoides Intestine Euryglossn orientalis Intestine Procnmallanus sp. Pseudorhombus arsius Ovary Philometra P.e/evatus Ovary lateolabracis P.javnnicus Ovary P.triocellatus Ovary Psettodes enrmei Body cavity belonging to the family Pleuronectidae, Body cavity, visceral organs, gonads and Psettodes erumei (Schneider) belonging to the muscle of the host fishes were separated and family Psettodidae and Aesopia conzuta (Kaup), examined thoroughly for nematode parasites. Euryglossa orientalis (Schneider), Solea ovata Each organ was teased by needle to locate the Riclmclson, Synaptura commersoniarta Gcepede) parasite einbeded in the tissues. The number, Zebrias altipin~tis(Alcock) and Z. syrzapturoides position and pathological symptoms at and (Jenkins) belonging to the family Soleidae. around the point of attachment were recorded. A. BUUKUMAR

TAB= 2. Nature of nematode infection in different flatfish species b Parasite Host Number of Number of fish infected No. of parasites fish examined (Prevalence in %) collected (Mean intensity) Hysterodrylacium Bothus myn'aster 45 38 184 sp.1 (larva) (84.4) (4.8) Crossorhombus Azureus 62 56 159 (90.3) (2.8) Engyprosoopon 55 55 290 grnndisquamii (100.0) (5.3) Laeops nigrescens 30 23 32 (76.7) (1.4) Pseudorhombus arsius 45 45 612 (100.0) (13.6) P.elantus 85 85 453 (100.0) (5.3) P.jamniars 36 36 27 1 (100.0) (7.5) P.lrioceIIatrrs 60 60 304 (100.0) (5.1) CynogIossus are1 254 109 262 (42.9) (2.4) C.dubius 121 27 43 (22.3) (1.6) C.lida 118 7 8 (5.9) (1.1) C.macrmtomus 259 73 % (28.2) (1.3) C.puncticeps 55 3 8 (5.5) (2.7) Samaris cristatus 48 29 41 (60.4) ' (la4) Psettodes erumei 55 2 1 33 (38.2) (1.6) Aesopin cornuta 48 11 14 (22.9) (1.3) Synaplurn commersoninna 52 7 13 (13.5) (1.9) Zebrias altipinnis 36 9 10 (25.0) (1.1) Z.g*napturoides 61 18 24 (29.5) (1.3) Hysterodrylacium Cynoglossus arel 254 4 4 sp.2 (larva) (1.6) (1.0) Hysterothylacium Crossorhornbus azureus 62 2 2 nduncum (3.2) (1.0) Pseudorlwmbus jmnnicus 36 2 2 (5.6) (1.0) CynogIossus are1 254 3 3 (1.2) (1.0) Snmaris cristalus 48 2 2 (4.2) (1.0) NEMATODE PARASITES ASSOCIATED WITH THE FLATFISHES

TABLE2. Contd... Zebrias qwapturoides 61 2 2 (3.3) (1.0) Prommallanus Euryglossa orientalis 65 1 1 9P- (1.5) (1.0) Philometra Pseudorhombus arsius 45 8 12 Iatedabracis (17.8) (1.5) P.elmtus 85 12 17 (14.1) (l.4) P.javanicus 36 6 11 (16.7) (1.8) P.&ellatus 60 6 9 (10.0) (1.5) Psettodu erumei 55 7 10 (12.7) (1.4)

Nematodes collected were cleaned off mucus, restricted more to the estuaries. Hystero- and killed in 70% ethanol and preserved in thylacium sp. 1 (larva) infected mainly intestine 70% glycerol-alcohol. Parasites were cleared in and mesenteries. However, in C)~noglossiisarel, lactic acid for identification. this larva invaded the muscles. H~vsterotltylacium .sp. 2 (larva) was collected from the ovary of OBSERVA'ITON AND DISCUSSION Cynoglossus arel. Five species of nematode parasites including Hysterothylacium sp. 1 larva, Hystero- Both prevalence and mean intensity of thylacium sp. 2 larva, Hysterothylacium Hysterotl~ylaci~msp. 1 larva were considerably aduncum Rudolphi, 1802 - Procamallanus sp. higher than that of Hysterotltylaciunt sp. 2 and Philometra lateolabracis Yamaguti, 1935 (larva). Prevalence of infection with the former (Deardorff and Overstreet, 1981a), were species was 100% .in all the four species of collected from 21 species of flatfishes. A list the genus Pseudorliombus and in E~tgyprosopoit of nematode parasites collected, their hosts and grandisquamis. Mean intensity of infection with site of infection are given in Table 1. The this species was also higher in these fishes. prevalence and mean intensity of these parasites in different hosts are presented in Table 2. Hysterotltylacium sp. 1 larva was represented mainly by the fourth stage larvae Twenty out of the twenty-one species of and less often by the third stage larvae. flatfishes examined harboured one type of Hysterotltylacium sp. 2 larva differ from the nematode species or the other. Multiple infection forcler in possessing long ventricular appendix, with different types of parasites was also exceeding the mid body. Further, tenninal spike common. Solea ovata was found free of observed in species 1, was lacking in this larva. nematode infection. Out of the twenty-one species of flatfishes Except Psettodes eriimei and Cyitoglossus examined, nineteen were infected with arel all the other 17 species of flatfishes infected Hysterothylacium sp. 1 (larva). Interestingly the are new host records for Hysterotliylacium sp. two species of fishes (Euryglossa orientalis and This is the first record of Hysterotltylacilrm sp. Solea ovata) found free of this parasite, were from Indian fishes. 38 A. BJJUKUMAR

H. aduncum infection occurred in the fishes and only one juvenile specimen was intestine of Crossorlzombus azureus, Pseudor- obtained from the intestine of estuarine flatfish hombus javanicus, Cyrtoglossus are!, Samaris Ell~glossaorientalis. E.orienta1i.s is a new host cristatus and Zebrias synapturoides. All the for Procamallanus sp. host fishes infected with this parasite in the Philometra lateolabracis is a common present study are new hosts for this parasite. parasite in the gonads of marine fishes (Kalyankar, 1971b; Mohan, 1971; Rama- and According to 'hne (1984)y chandran, 1975; Sood, 1988). In the present

Anden 986) and KOie 993)9 Hystero- studv P. lateolabracis infection occurred in the tlt~laciumis a COn~monparasite of flatfishes. ovaries of Pseudorltombus arsius, P. elevatus, The ascandoid genus ~ysterotlzylacium.ward P. javanicus and P. triocellatus, whereas in & Magath, 1917 was revised by Deardorff and Psettodes erumei this parasite was found in the Oventreet (1981). Species now included in this body cavity, &ached to the visceral organs. genus were previously referred to as Contra- The infection of the ovary of Pseudor- caecum and Tliynnascaris. According to this lrombus spp. by Pfiilomena lateolabracis at times revised classification Hysterothylacinm carangis was so heavy that the ovary was practically described by Kalyankar (1971a) from Carattx loaded with the parasites. The infection had a malabaricus is the only species of this genus ' prevalence of 13.9%. Infected ovaries appeared described from India. swollen and there was considerable ova atrophy; eggs were located only towards the anterior Overstreet and Meyer (1981) reported that tip of the ovary. the nematode H~~sterotltylaciumsp. infecting the flatfish 'Paralichtliys lethostigma is a Higher prevalence of Hysterotliylacium zoonotic form capable of infecting human spp. and Philometra lateolabracis in flatfishes beings. Nineteen out of the 21 species of is a matter of' great concern and more flatfishes examined during the present study investigations are warranted to find out the harboured Hysterotl~ylaciumsp. The prevalence zoonotic potential, if any, of Hysterothylaci~tm and mean intensity of this parasites were also spp. and to study the extent of damage caused high. Procamallanus sp. is one of the most by the nematode, P. lateolabracis infecting the common nematode genera reported from Indian ovaries.

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