SEASONAL DISTRIBUTION OF NEMATODES

Transcription

1 SEASONAL DISTRIBUTION OF NEMATODES

2 INTRODUCTION The seasonal distribution of parasites is an important factor to understand the intensity of infection in the edible fishes of a given region. The distribution of nematode parasites mainly carried by the infected host which may be harmful, such hosts and parasite relationship is parasitosis. In some infections to the hosts where there is no damage of tissue, such relationship between them is referred to as parasitiasis. Thus the distribution of nematode parasites in any given area much depends on either parasitosis or parasitiasis or both (Plate no 56, Fig no 1-6). In some nematode parasites like anisakids, release their eggs into the water where they become larvae and lead a zooplanktonic life and carried to different places till they find entry into the fish host. Nematode larvae are more harmful than adults and can penetrate into the tissue of various organs. Livers are more frequently invaded by the larvae, quiet often hundreds of them are present in this organ, causing severe tissue damage and destruction of cells (Plate no 57, Fig. no 1-5). Due to their smaller size they can circulate within blood stream and can reach to any of the organ of the fish including brain, eye, skin, muscles and gills etc.

3 PLATE-56 Fig 1 : Liver infected with Nibea maculata. Fig 2 : Same. (Enlarged view) Fig 3 : Nematode cysts in the stomach of Saurida undosquamis. Fig 4 : Liver infected with Johnius sp. Fig 5 : Liver infected with Otolithus argenteus. Fig 6 : Stomach infected with Otolithus argenteus.

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5 PLATE-57 Fig 1 : Liver showing larval nematodes. Heavy infection showing complete destruction of the tissue in host Mulloidichthys auriflamma. Fig 2 : Viscera showing larval nematodes in Mulloidichthys auriflamma. Fig 3 : Eustrongylides sp larva infecting body cavity of C. punctatus. Fig 4 : Eustrongylides sp larva infecting intestine of C. punctatus. Fig 5 : Eustrongylides sp larva infecting intestine of C. punctatus.

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7 Distribution of nematode parasites in different marine fishes were examined from January 2007 to December Prevalence of infection, mean intensity and relative density were studied. In 2007, the highest prevalence of infection (38.5%) was recorded in May and the lowest (3%) in February. The highest mean intensity (3.3%) was observed in March and lowest in June (1.3%) and highest relative density (0.6%) was observed in May and lowest (0.1%) was recorded for three months i.e March, August and September (Table -1, Graph-1, 2, 3). In the year 2008, the highest prevalence (14.2%) was recorded in May and the lowest (1.4%) in November. The highest mean intensity (1.7%) was observed in July and lowest (1.0%) in September and November and highest relative density (0.2%) was observed in May and lowest in April, June and July and was nil in eight months i.e January, February, March, August, September, October, November and December (Table-2, Graph-1, 2, 3). In the year 2009, the highest prevalence (20%) was recorded in May and the lowest (1.5%) in November. The highest mean intensity (1.5%) was observed in August and lowest (1.0%) in November and highest relative density (0.2%) was observed in May and was nil in six months i.e January, February, July, August, November and December (Table-3, Graph-1, 2, 3). The present study deals with the effect of seasons on total nematode population from the hosts collected during three annual cycles,

8 Each annual cycle comprises (1) Rainy Season (July to October) (2) Winter Season (November to February) (3) Summer Season (March to June) From the table-4, it indicates that in three years, the incidence of infection was moderate in winter and has risen considerably in rainy season and reached its peak in summer season (Graph-4). To understand, which species of marine fish is more prone to nematode infection, an in-depth study was conducted. In these three years the highest prevalence of infection was recorded in the fish Upeneus vittatus (62.5%) and lowest (8%) in Muraenesox talabanoides (Table-5). The prevalence in other fishes observed has been as follows- Thryssocles mystax (50%), Upeneus sulphureus (50%), Saurida undosquamis (46.6%), Decapterus russelli (44%), Trachinocephalus myops (41.6%), Apogon glaga (41.6%), Lutianus bohar (41.6%), Alectis indica (40%), Pentaprion longimanus (40%), Pterois russelli (37.5%), Thryssocles dussumieri (36.6%), Johnius sina (33.3%), Aesopia cornuta (33.3%), Saurida tumbil (30%), Sphyraena langsar (30%), Johnius dussumieri (30%), Linophora vagabunda (30%), Cynoglossus bilineatus (30%), Mulloidicthys auriflamma (27.5%), Trichiurus savala (22.5%), Holocentrus lacteo-guttatus (20%), Johnius axillaris (20%), Johnius aneus (20%), Drepane

9 punctata (13.6%), Muraenesox cinereus (13.3%) and Nibea maculata (12%) (Graph 5-10). It is evident from this study, that nematode parasites exhibit a marked seasonal occurrence, as the peak infection was recorded among the fish Upeneus vittatus, Thryssocles mystax, Upeneus sulphureus, and Saurida undosquamis with the occurrence of Contracaecum in the summer season i.e. from March to June (Table-6, Graph-11, 12).

10 TABLE-1 PREVALENCE, MEAN INTENSITY AND RELATIVE DENSITY OF NEMATODE INFECTION RECORDED FROM MARINE FISHES OF VISAKHAPATNAM COAST, FROM JANUARY TO DECEMBER MONTH NO. EXAM NO. INF TOTAL P. PREVALENCE M.I R.D JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER TOTAL Standard Deviation = 1.15 NO. EXAM = NUMBER OF EXAMINED FISHES, NO. INF =NUMBER OF INFECTED FISHES, TOTAL P. = TOTAL PARASITES, M.I = MEAN INTENSITY, R.D = RELATIVE DENSITY

11 TABLE-2 PREVALENCE, MEAN INTENSITY AND RELATIVE DENSITY OF NEMATODE INFECTION RECORDED FROM MARINE FISHES OF VISAKHAPATNAM COAST, FROM JANUARY TO DECEMBER MONTH NO. EXAM NO. INF TOTAL P. PREVALENCE M.I R.D JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Standard Deviation = 0.68 NO. EXAM = NUMBER OF EXAMINED FISHES, NO. INF =NUMBER OF INFECTED FISHES, TOTAL P. = TOTAL PARASITES, M.I = MEAN INTENSITY, R.D = RELATIVE DENSITY

12 TABLE-3 PREVALENCE, MEAN INTENSITY AND RELATIVE DENSITY OF NEMATODE INFECTION RECORDED FROM MARINE FISHES OF VISAKHAPATNAM COAST, FROM JANUARY TO DECEMBER 2009 MONTH NO. NO. TOTAL % OF M.I R.D EXAM INF P. PREVALENCE JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Standard Deviation = 0.48 NO. EXAM = NUMBER OF EXAMINED FISHES, NO. INF =NUMBER OF INFECTED FISHES, TOTAL P. = TOTAL PARASITES, M.I = MEAN INTENSITY, R.D = RELATIVE DENSITY

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14 TABLE-4 PREVALENCE AND MEAN INTENSITY OF NEMATODE INFECTION RECORDED SEASONWISE IN MARINE FISHES OF VISAKHAPATNAM COAST ( ) YEAR SEASON NO OF EXAMINED FISHES NO OF INFECTED FISHES TOTAL PARASITES PREVALENCE (%) MEAN INTENSITY + S.D 2007 RAINY WINTER SUMMER RAINY WINTER SUMMER RAINY WINTER SUMMER

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16 TABLE-5 PREVALENCE OF INFECTED MARINE FISHES AND PERCENTAGE OF NEMATODE INFECTION FROM JANUARY 2007 TO DECEMBER S.NO NAME OF FISH NO.OF EXAMINED FISHES NO.OF INFECTED FISHES PREVALENCE NEMATODES RECOVERED (No) MEAN INTENSITY ORDER:CLUPEIFOR MES FAMILY:ENGRAULI DAE A N C H O V I E S THRISSOCLES MYSTAX THRISSOCLES DUSSUMIERI ORDER: SCOPELIFORMES FAMILY:SYNODON TIDAE L IZARD FISHES SAURIDA UNDOSQUAMIS SAURIDA TUMBIL TRACHINOCEPHALUS MYOPS ORDER: ANGUILLIFORMES FAMILY: MURAENESOCIDAE FALSE CONGER EELS ORDER: BERYCIFORMES FAMILY: HOLOCENTRIDAE SOLDIER FISH MURAENESOX CINEREUS MURAENESOX TALABANOIDES HOLOCENTRUS LACTEO- GUTTATUS

17 ORDER: MUGILIFORMES FAMILY: SPHYRAENIDAE SEAPIKE ORDER: PERCIFORMES FAMILY: APOGONIDAE CARDINAL FISH FAMILY: CARANGIDAE TREVALLY SPHYRAENA LANGSAR APOGON GLAGA DECAPTERUS RUSSELLI ALECTIS CILIARIS FAMILY:LUTIANID AE SNAPPER LUTIANUS BOHAR FAMILY: GERRIDAE SILVER-BIDDIES FAMILY: SCIAENIDAE JEWFISH PENTAPRION LONGIMANUS NIBEA MACULATA JOHNIUS DUSSUMIERI JOHNIUS SINA JOHNIUS AXILLARIS JOHNIUS ANEUS

18 FAMILY: MULLIDAE GOAT FISH UPENEUS SULPHUREUS UPENEUS VITTATUS FAMILY: DREPANIDAE SPOTTED BAT FISH FAMILY : CHAETODONTIDAE CORAL FISH FAMILY: TRICHIURIDAE RIBBON-FISH FAMILY: SCORPAENIDAE STING-FISH ORDER:PLEURONE CTIFORMES FAMILY : SOLEIDAE HORNED SOLE FAMILY: CYNOGLOSSIDAE TONGUE-SOLES MULLOIDICTHYS AURIFLAMMA DREPANE PUNCTATA LINOPHORA VAGABUNDA TRICHIURUS SAVALA PTEROIS RUSSELLI AESOPIA CORNUTA CYNOGLOSSUS BILINEATUS

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21 TABLE-6 LIST OF FISHES WITH NEMATODE INFECTION SNO NAME OF THE FISH NAME OF THE PARASITE RECOVERED 1 THRISSOCLES MYSTAX CONTRACAECUM VITTATI NUMBER OF PARASITES RECOVERED 32 LOCATION OF THE PARASITE BODYCAVITY,STOMACH,LIVER,INTESTINE, MUSCLES 2 THRISSOCLES DUSSUMIERI PARANISAKIS SP I 10 LIVER, PORROCAECUM SP 5 STOMACH 3 SAURIDA UNDOSQUAMIS CONTRACAECUM SP 19 BODY CAVITY, STOMACH, INTESTINE 4 5 SAURIDA TUMBIL TRACHINOCEPHALUS MYOPS INDOCUCULLANUS ARABIANSAE CONTRACAECUM SP 9 6 INTESTINE AIRBLADDER 6 MURAENESOX CINEREUS RAPHIDASCARIS SP 3 INTESTINE 7 MURAENESOX TALABANOIDES RAPHIDASCARIS SP 2 INTESTINE 8 HOLOCENTRUS LACTEOGUTTATUS NEOGOEZIA ASPINOSA RAPHIDASCAROIDES SP II 1 STOMACH 4 STOMACH 9 SPHYRAENA LANGSAR PARANISAKIS SP I 5 INTESTINE 10 APOGON GLAGA CONTRACAECUM SP 5 BODY CAVITY 11 DECAPTERUS RUSSELLI CONTRACAECUM SP 12 STOMACH, INTESTINE 12 ALECTIS CILIARIS RAPHIDASCARIS DIADONIS 7 INTESTINE

22 13 LUTIANUS BOHAR PARACAMALLANUS SP 7 STOMACH 14 PENTAPRION LONGIMANUS CONTRACAECUM VITTATI 15 LIVER, INTESTINE NIBEA MACULATA JOHNIUS DUSSUMIERI RAPHIDASCARIS SP RAPHIDASCAROIDES SP I PORROCAECUM SP INTESTINE INTESTINE OVARIES JOHNIUS SINA JOHINUS AXILLARIS CONTRACAECUM VITTATI PARANISAKIS SP I 12 4 BODY CAVITY BODYCAVITY 19 JOHNIUS ANEUS PORROCAECUM SP 4 AIRBLADDER 20 UPENEUS SULPHUREUS CONTRACAECUM VITTATI 20 STOMACH, LIVER, INTESTINE 21 UPENEUS VITTATUS CONTRACAECUM VITTATI 30 BODY CAVITY,STOMACH 22 MULLOIDICTHYS AURIFLAMMA GENDRIA SP RHABDOCHONA SP II LIVER STOMACH 23 DREPANE PUNCTATA PARANISAKIS SP I 5 LIVER 24 LINOPHORA VAGABUNDA RHABDOCHONA SP I 5 INTESTINE 25 TRICHIURUS SAVALA ALIASCARIS SP CAMALLANUS SAVALA N.SP 6 8 LIVER, INTESTINE INTESTINE

23 26 PTEROIS RUSSELLI CONTRACAECUM VITTATI PARANISAKIS SP II PROLEPTUS SP 27 AESOPIA CORNUTA CONTRACAECUM VITTATI 3 BODY CAVITY 2 OVARY 1 STOMACH 1 BODY CAVITY 28 CYNOGLOSSUS BILINEATUS CONTRACAECUM SP 11 BODY CAVITY,STOMACH,INTESTINE

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25 EFFECT OF TEMPERATURE ON THE INTENSITY OF INFECTION IN MARINE FISHES Environmental factors are of crucial importance influencing the parasitic infection in fish and the subsequent expression of pathogenic potential. It has been observed that the nematode infection relates to the environmental factors like temperature and salinity. These two important parameters distinctly influence the intensity of nematode infection in the marine fish community. It has been observed in the laboratory, 2ml of C of habitat water when added to an active nematode, which influences to restrict the movement. In a similar way 40 0 C +1 0 increases the activity of the nematode parasites. This shows clearly the effect of temperature is directly proportional to the intensity of activity of a nematode which influences the intensity of infection. This factor clearly has been observed in the marine environment where the intensity of nematode infection to the fish is higher during the periods of high temperature and less infection during the periods of low temperatures. On the basis of the available information provided by the National Institute of Oceanography (N I O) that the marine environment especially of the coastal regions there are two peaks of high temperatures in each year recorded from 2007 to In these peak periods the intensity of nematode

26 infections was also recorded high. This is an indication that the high temperature of the coastal marine environment plays an important role for the intensity of nematode infection to the marine fish. In the year 2007, two peaks of high temperatures were recorded. The first peak of high temperatures C and C were recorded during the month of May and June respectively. In these two months the high intensity of nematode infection among the fish is recorded as 62.8% and 31.2% respectively. Among the infected fish Thryssocles mystax and Upeneus sulphureus were infected by the nematode parasite Contracaecum vittati. The second peak of high temperatures i.e C and C were recorded during the month of September and October respectively. In these two months the intensity of nematode infection in the fish is also high as 16.6% and 24.6% respectively. Mulloidicthys auriflamma and Alectis indica were infected by the nematode parasite Rhabdochona sp and Raphidascaris diadonis (Graph 13). In the year 2008 the first peak of high temperatures C and C were recorded during the month of May and June respectively. In these two months the high intensity of nematode infection among the fish is recorded as 22.8% and 15.2% respectively. Among the infected fish Saurida undosquamis and Johnius sina were infected high by the nematode parasite Contracaecum sp and Contracaecum vittati. The second peak of high temperatures C

27 and C were recorded during the month of September and October respectively. In these months the intensity of nematode infection in the fish is also high as 5.7% and 9% respectively. Pentaprion longimanus and Trachinocephalus myops were infected by the nematode parasite Contracaecum vittati and Contracaecum sp (Graph 13). In the year 2009 the first peak of high temperatures C and C were recorded during the month of May and June respectively. In these two months the high intensity of nematode infection among the fish is recorded as 24.2% and 18% respectively. Among the infected fish Upeneus vittatus, Saurida tumbil and Trichiurus savala were infected high by the nematode parasite Contracaecum vittati, Indocucullanus arabiansae and Camallanus savala n.sp. The second peak of high temperatures C and C were recorded during the month of September and October respectively. In these months the intensity of nematode infection in the fish is also high as 11.7% and 14.2% respectively. Among the infected fish Sphyraena langsar, Thyrissocles dussumieri and Cynoglossus bilineatus were infected high by the nematode parasite Paranisakis and Contracaecum sp (Graph 13). The low temperatures were recorded as C, C and C during the months of January, November and December

28 respectively in the year In these three months the percentage of infection is nil. In other months less intensity of infection was observed (Graph 13). The low temperatures were recorded as C, C and C during the months of January, February and December respectively in the year In these three months the percentage of infection is nil. In other months less intensity of infection was observed (Graph 13). The low temperatures were recorded as C and C during the months of January and December respectively in the year In these two months the percentage of infection is nil. In other months less intensity of infection was observed (Graph 13).

29 EFFECT OF SALINITY ON THE INTENSITY OF INFECTION IN MARINE FISHES Salinity is another important parameter for the survival of animals in the marine environment and regulates their distribution. During this study data has been collected to examine the influence of salinity on infection and distribution of nematode parasites in the coastal marine waters of Visakhapatnam. According to the information of the operators of the trawlers and fishing boats, they operate between 5 to 90 meters depth. Information on salinity in the coastal waters of Visakhapatnam coast has been obtained from National Institute of Oceanography (N I O) for a period of three years i.e from January 2007 to December During this period there was not much variation in salinity in the horizontal depth stratification. Salinity ranged between o / oo to o / oo (Graph 13).

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