trematode crvenpeka

Nedić Z. i sar.: Ectoparasitic trematodes on Scardinius erythophthalmus from the lower flow of...

Veterinaria 64 (1-4), 37-44, Sarajevo 2014. 37

NAUČNI RAD – Original Paper

ECTOPARASITIC TREMATODES ON Scardinius erythrophthalmus

FROM THE LOWER FLOW OF THE SAVA RIVER

EKTOPARAZITSKE TREMATODE NA VRSTI Scardinius

erythrophthalmus IZ DONJEG TOKA RIJEKE SAVE

Nedić Z., Riđanović S., Halilović E.1

Sažetak – Istraživanjem ektoparazitskih trematoda na vrsti Scardinius

erythrophthalmus donjeg toka rijeke Save ustanovljene su tri vrste trematoda koje

parazitiraju na škrgama ili koži riba. Tokom istraživanog perioda uzorkovali smo 120

jedinki vrste Scardinius erythrophthalmus. Ukupno 85 jedinki ili više od 70% pokazalo je

prisustvo jedne od tri ustanovljene ektoparazitske trematode. Determinacija trematoda

provedena je do nivoa vrste za jednu trematodu (Posthodiplostomum cuticola) i do nivoa

roda za dvije (Dactylogyrus i Gyrodactylus).

Ključne riječi: rijeka Sava, donji tok Orašje, ektoparazitske trematode

Abstract – The research on ectoparasitic trematodes on Scardinius

erythrophthalmus from the lower flow of the Sava River showed three species of

trematodes, which parasitized on the fish gills and fish skin. During the study period, we

sampled 120 individuals of Scardinius erythrophthalmus. In total, 85 individuals or more

than 70% showed the presence of one of the three types of ectoparasitic trematodes.

Determination of the trematodes was done to the species level for one species

(Posthodiplosomum cuticola) and to the genus level for two of them (Dactylogyrus and

Gyrodactylus).

Key words: Sava River, lower flow, Orašje, ectoparasitic trematodes

1 Zlatko Nedić, magistar primijenjene biologije, ([email protected]), Srednja

strukovna škola Orašje; Sanel Riđanović; docent, Nastavnički fakultet,Univerzitet Džemal Bijedić,

Mostar; Emir Halilović, magistar bioloških nauka, Univerzitetski klinički centar Tuzla

Zlatko Nedić, Master of Applied Biology, ([email protected]), Secondary

vocational school of Orašje; Sanel Riđanović; PhD, Assistant Professor, Faculty of Education,

University of Džemal Bijedić, Mostar ;Emir Halilović, Master of biological science, University

Clinical Center of Tuzla


38

Introduction

Sava is the largest river which makes the border between Croatia and Bosnia and

Herzegovina (Fig. 1) (2). This highlights the importance of research on such ecosystem in

biological sense. In this regard, the study of ectoparasitic trematodes on fish in Sava can

contribute to a better understanding of biotic environmental factors that occur as products

of interrelations between ectoparasitic trematodes and fish specimens in its watercourse.

Trematodes represent a very heterogeneous group of invertebrates, where many of them

build complex ecological relationships (parasitism, commensalism, etc.) (8). Defining the

number of ectoparasitic trematodes which parasitize on fish may prove their biological

diversity, and therefore, the heterogeneity of the lower flow of the Sava River in terms of

parasitofauna and parasites that are more or less specific to species Scardinius

erythrophthalmus. By this, we can determine the health status of the fish individuals of

the Sava River in the area because some ectoparasitic trematodes produce certain

metabolic products (appearance of mucus on the skin, minor wounds, hematoma, etc.)

that can be harmful to the health of fish (3). The main objective of our research is to

determine the types of ectoparasitic trematodes that exist on the fish skin and fish gills,

and the intensity of the infection of these individuals. Second objective is to understand

seasonal dynamics of the trematodes presence. Our hypothesis is that in the lower flow of

the Sava River several species of ectoparasitic trematodes (most probably Gyrodactylus

and Dactylogyrus species) exist in the highest number on high temperature.

Material and methods

For research purposes, the sampling was done at four locations near Orašje town

(Fig. 1). We sampled 120 fish individuals of Scardiniu serythrophthalmus. During the

research some basic physical parameters of the river were measured, i.e. water

temperature and water level, which are important for the survival of

ectoparasitictrematodes (3). Temperature was measured by the mercury thermometer, and

data on the height of water level were used from the Water Management Enterprise

Central Posavina. During the study and electrical microscope (Olympus) and native

preparation taken from the fish gills and skin were used.

Sampling was carried out in summer and autumn of 2013, and the fish was

caught in cooperation with the local fishermen. After the fish had been caught, they were

anesthetized with MS 222, and decapitated. After systematic determination of the fish

individuals by the identification key for freshwater fish species (9), all sampled

individuals were examined and searched for the presence of ectoparasitic trematodes. For

parasitological examinations, we made native preparations of the samples taken from the

skin and gills. Native preparations were microscopically analyzed using an electrical

microscope (Olympus) under 10x and 40x magnification, and than the ectoparasitic



trematodes were determined (3). Statistical analysis was performed using non-parametric

statistical test (chi-square test) in the computer program Statistica 7TM

.

Results

Study of the ectoparasitic trematodes on Scardinius erythrophthalmus from the

lower flow of the Sava River was conducted at four locations, where we sampled 120 fish

individuals, approximately 30 individuals from every location. By measuring the

fundamental physical parameters of the Sava River, we determined the average water

temperature during the summer period to be 25 °C, while during the autumn period the

average temperature was 19 °C. Water level according to the Water Management

Enterprise Central Posavina measured several times during the summer period, was -43

cm and -80 cm.

Fig. 1. Sampling locations on the lower flow of the Sava River near Orašje townFigure shows

northern Bosnia and Herzegovina bordering on the Republic of Croatia. This area has continental

climate. L1, L2, L3 and L4 indicate sampling locations from west to east.

Slika 1. Lokacije uzorkovanja na donjem toku rijeke Save u blizini grada Orašja. Slika prikazuje

sjevernu Bosnu i Hercegovinu koja graniči sa Republikom Hrvatskom. Ovo je područje

kontinentalne klime. L1, L2, L3 i L4 označavaju lokacije uzorkovanja od zapada prema istoku

Microscopic analysis of native preparations of the fish skin and fish gills, and

the search for the presence of ectoparasitic trematodes discovered three species of

trematodes: Dactylogyrus sp., Gyrodactylus sp. and Posthodiplostomum cuticola (Fig 2

and 3, Graph 1 and 2).


40

In the total fish sample, we found 85 infected individuals so we point out that the

number of infected and non-infected individuals is statistically significant (p<0,05). We

can argue that the infection by the trematodes is high, because statistical, the number of

infected individuals is higher than number of non-infected individuals (Graph 1). 50

individuals were infected by Dactylogyrus species, 33 fish individuals were infected by

Gyrodactylus species, and 85 were infected by species Posthodiplostomum cuticola

(Table 1). Number of infected and non-infected individuals by Dactylogyrus is not

significant (p>0,05), but by Gyrodactylus species and Posthodiplostomum cuticola is

(p<0,05). We can argee that the infection with Posthodiplotomum cuticola is not

consequence of accident, and that this species has very high affinity to parasitize on

Scardinius erythrophthalmus (Graph 2)

Figure. 2. Native preparation of fish gill showed the presence of Dactylogyrus sp. under

magnification 40x

Slika 2. Nativni preparat škriga ribe pokazao je prisustvo vrste iz roda Dactylogyrus pod

uvećanjem 40x



Figure. 3. Infection by Posthodiplostomum cuticola

Slika 3. Infekcija vrstom Posthodiplostomum cuticola

Table 1.Number and average of infected and non-infected sampled individuals

Tabela 1. Broj i postotak inficiranih i neinfciranih jedinki

Trematodes species No of infected fish

individuals

% of infected individuals

in the total sample

Dactylogyrus sp. 50 41.66

Gyrodactylus sp. 33 27.50

Posthodiplostomumcuticola 85 70.83

Total 85 70.83

Graph 1. Percentage of infected and non-infected individuals of Scardinius erythrophthalmus

Grafikon 1. Procenat inficiranih i neinficiranih jedinke vrste Scardinius erythrophthalmus

71%

29%

Percentage of infected and non-infected fish individuals

infected individuals non infected individuals


42

Graph 2. Number of infected individuals by established ectoparasitic trematodes

Grafikon 2. Broj inficiranih jedinki ustanovljenim ektoparazitskim trematodama

Graph 3. Seasonal dynamics of Scardinius erythrophthalmus infection by three types of

ectoparasitic trematodes

Grafikon 3. Sezonska dinamika infekcije vrste Scardinius erythrophthalmus sa tri vrste

ektoparazitskih trematoda

Discussion

In present study we point out that the temperature in summer was extremely

favorable for the development of the ectoparasitic trematodes, while the autumn

temperatures were less favorable for their development (6). Some authors disagree with

this thesis arguing that some trematodes species are highly tolerant on habitat

temperature, and the level of tolerance ranges from 2 ºC to 9 ºC (5).

0

50

100

Dactylogyrus sp. Gyrodactylus sp. P. cuticola

Nu

mb

er

of

infe

cte

d

ind

ivid

ual

s

Different types of trematodes

Number of infected individuals by three types of trematodes

0

5

10

15

20

25

30

35

July August September October

Nu

mb

er

of

infe

cte

d f

ish

in

div

idu

als

Sampling period

Dactylogyrussp.

Gyrodactylussp.

P. cuticola



It was very easy to determine parasite species Posthodiplostomum cuticola as

this species creates very recognizable black spots on the skin and fins (7). The population

of Scardinius erythrophthalmus is very densely distributed, which can contribute to the

infection with P. Cuticola. It is important to emphasize that we found P. cuticola on the

fish skin and fins, but not on the gills. Some authors found this species most abundant on

the skin, but less abundant on the gills (7). Intensity of the infection with the species P.

cuticola was very high on the skin and fins of infected individuals. Species from the

genus Dactylogyrus were very often found on the fish populations, especially cyprinid

fish (1). We found 50 infected fish individuals with species from genus Dactylogyrus. In

our research, we point out that the intensity of infection by this parasite type was very

high. Kiškaroly and Tafro (4) found species from genus Dactylogyrus and

Gyrodactyluson the population of Scardinius erythrophthalmus in the Serbian

watercourses. In our results we found very high intensity of infection with the species

from genus Gyrodactylus. By comparative analysis of our results with the results of the

aforementioned authors, a great similarity can be noticed.

Seasonal dynamics of the infection is very interesting. We noted the highest

number of infected individuals in July and August, and smaller number in September and

October (Graph 3).

We point out that the water temperature is primary ecological factor for

developing the ectoparasitictrematodes. In July and August the temperature values were

very favorable for the trematodes’ life cycle. Ondračková at al. (6) presented similar

results in their study of Posthodiplostomum cuticola. Their study shows that temperature

values in August are very favorable for the trematodes to develop.

Conclusion

Parasitological examination for the presence of ectoparasitic tematodes on the

skin and gills demonstrated the infection in more than 70% of the fish examined.

In this research, we identified several species of ectoparasitic trematodes. We

determined one of them to the species level (Posthodiplostomum cuticola), and two of

them to the genus level (Dactylogyrus and Gyrodactylus). We conclude that the infection

of Scardinius erythrophthalmus with the ectoparasitic trematodes is severe and not

accidental. Especially severe infection is with Posthodiplostomum cuticola on the fin and

skin. Hence, we can argue that this parasite species has a very high affinity for Scardinius

erythrophthalmus individuals.

Therefore, we emphasize that the highest values of temperature can have

positive impact on the trematodes development.


44

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