occurrence of benedenia sciaenae 1856 (argyrosomus regius 6/vol 276 250.pdf · figure 1....
TRANSCRIPT
· . .
'- - , " _" _ _ "'- _ __ 00'''"- _'''"
Bull. Eur. Ass. Fish Pathol., 27(6) 2007, 2S0
Occurrence of Benedenia sciaenae van Beneden, 1856 (Monogenea: Capsalidae) in cultured
meagre (Argyrosomus regius Asso, 1801) (Teleost: Sciaenidae) from western Turkey
E. Toksen1*, K. Buchmann2 and J. BrescianF
1 Department of Aquaculture, Faculty of Fisheries, Ege University, Bornova, 35100, Izmir, Turkey;
2Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
Abstract
An investigation was conducted on the causes of scale loss and severe local lesions on the skin of cultured meagre (Argyrosomus regius Asso, 1801) reared in net cages in the Mediterranean along the Turkish host. This species is an important alternative species to the sea bass and sea bream in Turkish mariculture. All of the 40 fish examined (mean body weight S.63 kg SD 0.89 kg, mean body length 91.3 cm SD 3.6 cm) showed numerous monogenean parasites on the area with lesions. The parasite was identified as Benedenia sciaenae van Beneden, 18S6 (Monogenea : Capsalidae). The prevalence was 100 % and the mean intensity 227 (SD 77.5) parasites per host. Scanning electron micrographs of the causative parasite are presented. This is the first report of B. sciaenae in Turkey.
Introduction
The teleost Argyrosomus regius, which is a
member of the family Sciaenidae is
distributed along the Mediterranean, the Sea
of Marmara, along the west cost of the Black
Sea, the Red Sea and occasionally in the Indian
Ocean (Quemer, 2002). It has been accepted
as an alternative species having a high
potential in aquaculture due to its fast growth,
high feed conversion ratio, survival under a
wide range of salinities and its excellent flesh
quality (Poh et aI., 2001). Thus, growth trials
including this species have been done in Italy,
France and Turkey (Stipa & Angelini, 200S).
The first commercial production was
established in Turkey during 200S but farmers
reported occurrence of scale losses and skin
lesions already during the first season.
* Corresponding authors E-mail: [email protected]
Therefore the present investigation was
conducted in order to elucidate possible
causes. We hereby report on the occurrence
of B. sciaenae associated with the lesions and
discuss the possible parasitic impacts on
meagre.
Materials and methods
This study was carried out using fish collected
in a net cage located along the coast near
Akbiik (western part of Turkey) inApri1200S.
Forty specimens of Argyrosomus regius were
sampled. The fish were anesthetized with
phenoxyethanol and the total weight and
length of fish were measured. A large number
of parasites were observed with the naked eye
on the skin of the fish. They were collected
with tweezers, counted and investigated
Figure 1. Scanning electron microscopy of Benedenia scianeae, whole worm, ventral view, anterior attachment organs (arrows). Scale bar 1 mm.
under the light microscope. The prevalence,
parasite range and mean intensity (Bush et aI.,
1997) of the parasites were calculated for the
spring season. Some parasites were fixed in
4% neutral formaldehyde, brought to the
laboratory for further investigation and
measurements which were done by the use
of an Olympus BH2 binocular microscope
fitted with a calibrated eyepiece. Formalin
fixed parasites were post-fixed in 2.3% neutral
glutaraldehyde (24h), washed in distilled
water, immersed in 2% tannic acid,
dehydrated, critically point-dried, sputtered
with gold and studied in a FEI Quanta 200
ESEM scanning electron microscope.
Results
Cultured meagre (5.63 ± 0.89 kg in weight, 91.3
± 3.6 cm in length) with hemorrhagic lesions
and scale losses, were observed to rub the
body surface against the net of the cage. While
Bull. Eur. Ass. Fish PathoI., 27(6) 2007, 251
Figure 2. Scanning electron micrograph of opisthaptor (oh) with the marginal extension (black arrows) and protruding accessory sclerites (white arrows) and . Scale bar 500 !lm.
the reasons of these lesions were being
investigated, parasites as big as that can be
seen with the naked eye were found in the
hemorrhagic parts of the skin. The parasites
were identified as Benedenia sciaenae following
the diagnostic keys outlined by Yamaguti
(1963) and Whittington (2001). Measurements
obtained from forty specimens were as follow
(in micrometer) given as range and mean (in
parenthesis): total length of the parasite
including haptor: 10.000-17.000 (14.300)
(Figure 1), maximum breadth: 7.000-9.000
(8.200) at the level of testes. Haptor: 5.680-
6.400 (6.020) x 5.600 - 6.000 (5.800) (Figure 2).
Accessory sclerites: 640-1056 (848) (Figure 2).
Anterior hamuli: 260-325 (290), posterior
hamuli: 221-299 (256) (Figure 3). Moreover,
the opisthaptor had a marginal extension
surrounding the haptor as a skirt (Figure 2).
Anterior attachment organs were 1.360 -1.800
(1.580) x 1.280-1.640 (1.466) appearing more
muscular than glandular (Figure 4). Pharynx
was 1.680 -1.920 (1;800) x 1.520- 1.680 (1.600).
Genital pores were at next to the left anterior
I I
'I I
( j(
Bull. Eur. Ass. Fish Pathol., 27(6) 2007, 252
Figure 3. Posterior hamuli. Scale bar 40 f.1m.
haptor of parasites. Pigmentation was
observed on the dorsal side of the body. All
sampled fish were found to be infected
(prevalence 100 %). Totally, 9.088 monogenean
were counted in 40 infected fish. Parasite
abundance ranged from 84 to 386. Mean
intensity of parasite numbers was 227 (SD
77.5).
Discussion
Meagre has been cultured in aqua culture
farms as an alternative marine fish species in
some Mediterranean countries (Stipa & Angelini, 2005) but only few data are available
on the parasitic diseases of meagre. This
report documents the occurrence of B. scianeae
in cultured meagre in Izmir, Turkey and
suggest that the parasites are responsible for
pathological changes of the host skin. The
mono gene an B. sciaenae was first discovered
Figure 4. Scanning electron micrograph showing anterior part with the two adhesive pads (arrows). Scale bar Imm.
by van Beneden (1852) on the surface of the
European leanfish (Sciaena aquila) (now
Argyrosomus regius) and was followed by later
studies by Goto (1899), Palombi (1949),
Bussey (1986) and Whittington (1996)
reporting the parasite. In the present study,
parasites having a large body size, possession
of separate but closely apposed male and
female pores; and the posterior position of the
large accessory sclerites possessing distinctive
surrounding tissue in the haptor were
observed. These findings and measurements,
which are similar to those of Whittington
(1996), are important to distinguish species
in the genus Benedenia. The authors van
Beneden (1856) and Palombi (1949) reported
dark ruby pigment in the dorsal area. Dark
brown or black pigment aggregations
throughout the body and the haptor of the
parasite were observed in our study which
corresponds to observations by Whittington
(1996). Further, the measurements obtained
in this work clearly correspond to the
description of B. sciaenae done by Whittington
(1996). The scanning electron microscopy
studies revealed the main attachment organs,
opisthaptor, which was equipped with few
externally exposed sclerites and adhesive
pads. These could to some extent probably
inflict some damage to the host epidermis.
However, it is likely that also the feeding
activity itself (due to high parasite burdens
and high energy demand of the worms) may
be more important elements of pathogenesis.
The subsequent rubbing of the body surface
against various structures in the net-pens
(caused by skin irritation) may be responsible
for further skin damages. Generally, the high
prevalence and parasite occurrence associated
with the skin lesions suggest that these
parasites are rather pathogenic and at least
partly responsible for the pathological
changes of the host skin. Therefore the results
call for further studies on development of
sustainable control methods of this parasitosis
in order to secure production and welfare of
cultured meager.
Acknowledgements
The authors are indebted to Dr. 1. Whittington
for confirming the identity of the parasite.
References
BushAO, Lafferty KD, Lotz JM & Shostak AW (1997). Parasitology meets ecology on its own terms: Margolis et al. revisited. Journal of Parasitology 83, 575-583.
Goto S (1899). Notes on some exotic species of ectoparasitic trematodes. Journal of the College of Science, Imperial University of Tokyo 12, 263-295.
Bull. Eur. Ass. Fish Pathol., 27(6) 2007, 253
Hussey CG (1986). Some mono gene an parasites of marine perciform fishes of Kuwait. Journal of Natural History 20, 415-430.
Palombi A (1949). Trematodi Monogenetici. Archivio Zooligico Italiano 34, 203-408.
Poli BM, Parisi G, Mecatti M, Lupi P, Iurzan F, Zampacavallo G & Gilmozzi M (2001). The meagre (Argyrosomus regius), a new species for Mediterranean aquaculture. 1. Morphological, merchantable and nutritional traits in a commercial wide size-range. European Aquaculture Society Special Publication 29, 209-210.
Quemener L (2002). La maigre commun (Argyrosomus regius) Biologie, peche, marche et potential aquacole. Editions Ifremer, Plouzane, France.
Stipa P & Angelini M (2005). Cultered aquatic species information programme- Argyrosomus regius. Cultered Aquatic Species Fact Sheets. FAO-FIGIS.
van Beneden P J (1852). Note sur quelques parasites d'un poisson rare sur nos cotes (le Maigre d'Europe, Sciaena aquila Cuv). Bulletin l'Academie Royale de Belgique. Classes des Sciences 19, 98-109.
Whittington ID (1996). Benedeniine capsalid monogeneans from Australian fishes: pathogenic species, site-specificity and camouflage. Journal of Helminthology 70, 177-184.
Whittington ID (2001). A revision of Benedenia Diesing, 1858 including a redescription of B. sciaenae (van Beneden, 1856) Odhner, 1905 and recognition of Menziesia Gibson, 1976 (Monogenea: Capsalidae). Journal of Natural History 35, 663-777.
Yamaguti S (1963). "Systema Helminthum. Volume TV. Monogenea and Aspidocotylea." Inter Science Publishers, New York.