r e Rese Journal of Aquaculture - Longdom · density and monosex culture of freshwater prawn...
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Open Access Volume 3 • Issue 1 • 1000122 J Aquac Res Development ISSN: 2155-9546 JARD, an open access journal Open Access Paulraj et al., J Aquac Res Development 2012, 3:1 DOI: 10.4172/2155-9546.1000122 Open Access Keywords: Macrobrachium rosenbergii; Chytrid fungus; Infection; Pond culture Case Report Freshwater aquaculture has expanded rapidly in the Asia-Pacific region over the past three decades. For instance, the culture of giant freshwater prawn Macrobrachium rosenbergii in India reached 42,820 tonnes due to increased domestic consumption and exports [6]. However, freshwater prawn culture around the world has been challenged by the emergence of disease outbreaks. Particularly, attention has been paid to viral and bacterial diseases, but fungal diseases have also been reported [5,8]. While the epidemiological significance of such diseases in prawn culture remains uncertain, new concerns on M. rosenbergii aquaculture have emerged [9]. In the present study we describe a new disease with unusual clinical signs that was recognized in pond-cultured M. rosenbergii from southeast coast of Tamilnadu, India. Diseased M. rosenbergii (n = 525) were collected in 32 ponds around Chennai area (13º01’ N; 80º16’ E) from June to October 2005. e affected prawns were found with their carapace and abdomen covered by a thick layer of whitish hair (Figure 1A). Further, these prawns showed sluggish movement, decreased food intake and abnormal migration to the pond corners. ese clinical signs appeared aſter 3 to 4 months of juvenile stocking and were more pronounced in animals above 30 g of body weight. e external parasites were removed from the infected portions of the animals and stained with cotton blue and lactophenol. e identification procedures of isolates followed standard manuals [1,2,11,10] and revealed a fungal species of the class Chytridiomycetes. However, identification to the species level using usual techniques was unsuccessful until now, suggesting it could be a new fungal species. e class Chytridiomycetes was predominant (78%) in the infected animals. Pot-shaped chytrid fungi show branching filamentous mycelium and measure around 45 ± 2 μm (Figure 1B and 1C). eir hyphae are stout, slender, crooked, sympodially branched and pseudo- septated, measuring 12 to 85 μm in diameter at base, basal joints with 50 to 450 μm long and central joints up to 750 μm long. It is believed that this chytrid fungus can cause severe injuries to the animal by penetrating into the tissue resulting in high mortality. e first indication of the fungal infection is usually the dullness of the body colour and eye. e infected area can be easily distinguished from the surrounding tissue by the abnormal protrusion of the body surface even before the appearance of the fungus. Later, the fungus appears as a small tuſt growing in the centre of this region and the affected area increases in size as the fungus spreads. Fungal diseases are more prevalent in crustaceans than in any other marine invertebrates [16]. Previous studies have shown that most of fungal pathogens identified in aquaculture ecosystems are Phycomycetes [17,14]. Although, fungi with affinities to protistan groups such as raustochytrids and Labyrinthulids have been related to shellfish diseases, taxonomic misunderstandings are claimed by *Corresponding author: Silvio Peixoto, Universidade Federal Rural de Per- nambuco, Depto. Pesca e Aqüicultura, 52171-900, Recife, Brazil, E-mail: [email protected]/ [email protected] Received February 15, 2012; Accepted March 06, 2012; Published March 13, 2012 Citation: Paulraj A, Lima-Filho JV, Altaff K, Peixoto S (2012) Atypical Chytridiomy- ces Fungal Infection in Cultured Macrobrachium rosenbergii in India. J Aquac Res Development 3:122 doi:10.4172/2155-9546.1000122 Copyright: © 2012 Paulraj A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract In the present study we report ectoparasite infection in pond-cultured Macrobrachium rosenbergii from southeast coast of Tamilnadu, India. The symptoms included a thick layer of whitish hair covering the entire body, sluggish movement, decrease of food intake and abnormal migration to the pond corners. Laboratorial analysis identified fungi from the genus Chytridiomyces, which have been associated to mortalities during freshwater prawn culture in India. Atypical Chytridiomyces Fungal Infection in Cultured Macrobrachium rosenbergii in India Ambrose Paulraj 1 , José Vitor Lima-Filho 2 , Kareem Altaff 3 and Silvio Peixoto 4 * 1 Department of Zoology, Government Arts College, Dharmapuri - 636 705, Tamilnadu, India 2 Universidade Federal Rural de Pernambuco, Depto. Biologia, 52171-900, Recife, Brazil 3 Department of Zoology, The New College, Chennai – 600 014, Tamilnadu, India 4 Universidade Federal Rural de Pernambuco, Depto. Pesca e Aqüicultura, 52171-900, Recife, Brazil C A B Figure 1: Chytridiomyces fungal infection in pond-cultured Macrobrachium rosenbergii. Fungal colonization covering the entire body of the prawn (A). Mi- croscopic view of the chytrid fungus at the magnification of 100x (C) and 400x (B). Case Report Journal of Aquaculture Research & Development Jo u r n a l o f A q u a c u lt u r e R e s e a r c h & D e v e l o p m e n t ISSN: 2155-9546
Transcript of r e Rese Journal of Aquaculture - Longdom · density and monosex culture of freshwater prawn...
Open Access
Volume 3 • Issue 1 • 1000122J Aquac Res DevelopmentISSN: 2155-9546 JARD, an open access journal
Open Access
Paulraj et al., J Aquac Res Development 2012, 3:1 DOI: 10.4172/2155-9546.1000122
Open Access
Keywords: Macrobrachium rosenbergii; Chytrid fungus; Infection;Pond culture
Case ReportFreshwater aquaculture has expanded rapidly in the Asia-Pacific
region over the past three decades. For instance, the culture of giant freshwater prawn Macrobrachium rosenbergii in India reached 42,820 tonnes due to increased domestic consumption and exports [6]. However, freshwater prawn culture around the world has been challenged by the emergence of disease outbreaks. Particularly, attention has been paid to viral and bacterial diseases, but fungal diseases have also been reported [5,8]. While the epidemiological significance of such diseases in prawn culture remains uncertain, new concerns on M. rosenbergii aquaculture have emerged [9]. In the present study we describe a new disease with unusual clinical signs that was recognized in pond-cultured M. rosenbergii from southeast coast of Tamilnadu, India.
Diseased M. rosenbergii (n = 525) were collected in 32 ponds around Chennai area (13º01’ N; 80º16’ E) from June to October 2005. The affected prawns were found with their carapace and abdomen covered by a thick layer of whitish hair (Figure 1A). Further, these prawns showed
sluggish movement, decreased food intake and abnormal migration to the pond corners. These clinical signs appeared after 3 to 4 months of juvenile stocking and were more pronounced in animals above 30 g of body weight. The external parasites were removed from the infected portions of the animals and stained with cotton blue and lactophenol. The identification procedures of isolates followed standard manuals [1,2,11,10] and revealed a fungal species of the class Chytridiomycetes. However, identification to the species level using usual techniques was unsuccessful until now, suggesting it could be a new fungal species.
The class Chytridiomycetes was predominant (78%) in the infected animals. Pot-shaped chytrid fungi show branching filamentous mycelium and measure around 45 ± 2 μm (Figure 1B and 1C). Their hyphae are stout, slender, crooked, sympodially branched and pseudo-septated, measuring 12 to 85 μm in diameter at base, basal joints with 50 to 450 μm long and central joints up to 750 μm long. It is believed that this chytrid fungus can cause severe injuries to the animal by penetrating into the tissue resulting in high mortality. The first indication of the fungal infection is usually the dullness of the body colour and eye. The infected area can be easily distinguished from the surrounding tissue by the abnormal protrusion of the body surface even before the appearance of the fungus. Later, the fungus appears as a small tuft growing in the centre of this region and the affected area increases in size as the fungus spreads.
Fungal diseases are more prevalent in crustaceans than in any other marine invertebrates [16]. Previous studies have shown that most of fungal pathogens identified in aquaculture ecosystems are Phycomycetes [17,14]. Although, fungi with affinities to protistan groups such as Thraustochytrids and Labyrinthulids have been related to shellfish diseases, taxonomic misunderstandings are claimed by
*Corresponding author: Silvio Peixoto, Universidade Federal Rural de Per-nambuco, Depto. Pesca e Aqüicultura, 52171-900, Recife, Brazil, E-mail: [email protected]/ [email protected]
Received February 15, 2012; Accepted March 06, 2012; Published March 13, 2012
Citation: Paulraj A, Lima-Filho JV, Altaff K, Peixoto S (2012) Atypical Chytridiomy-ces Fungal Infection in Cultured Macrobrachium rosenbergii in India. J Aquac Res Development 3:122 doi:10.4172/2155-9546.1000122
Copyright: © 2012 Paulraj A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
AbstractIn the present study we report ectoparasite infection in pond-cultured Macrobrachium rosenbergii from southeast
coast of Tamilnadu, India. The symptoms included a thick layer of whitish hair covering the entire body, sluggish movement, decrease of food intake and abnormal migration to the pond corners. Laboratorial analysis identified fungi from the genus Chytridiomyces, which have been associated to mortalities during freshwater prawn culture in India.
Atypical Chytridiomyces Fungal Infection in Cultured Macrobrachium rosenbergii in IndiaAmbrose Paulraj1, José Vitor Lima-Filho2, Kareem Altaff 3 and Silvio Peixoto4*1Department of Zoology, Government Arts College, Dharmapuri - 636 705, Tamilnadu, India2Universidade Federal Rural de Pernambuco, Depto. Biologia, 52171-900, Recife, Brazil3Department of Zoology, The New College, Chennai – 600 014, Tamilnadu, India4Universidade Federal Rural de Pernambuco, Depto. Pesca e Aqüicultura, 52171-900, Recife, Brazil
C
A
B
Figure 1: Chytridiomyces fungal infection in pond-cultured Macrobrachium rosenbergii. Fungal colonization covering the entire body of the prawn (A). Mi-croscopic view of the chytrid fungus at the magnification of 100x (C) and 400x (B).
Case Report
Journal of AquacultureResearch & DevelopmentJo
urna
l of A
quac
ulture Research &Developm
ent
ISSN: 2155-9546
Citation: Paulraj A, Lima-Filho JV, Altaff K, Peixoto S (2012) Atypical Chytridiomyces Fungal Infection in Cultured Macrobrachium rosenbergii in India. J Aquac Res Development 3:122 doi:10.4172/2155-9546.1000122
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Volume 3 • Issue 1 • 1000122J Aquac Res DevelopmentISSN: 2155-9546 JARD, an open access journal
mycologists and protozoologists [14]. In the present study we faced a similar problem, as some of the protozoans and chytrid fungi occurred together and resembled each other morphologically. Nevertheless, the ecological relationship between fungi and protozoan appear to be as predator and prey, respectively [15]. Several flagellate groups are reported to be attacked by chytrid fungi, which penetrate the flagellate cells or produce a root like hyphae withdrawing their contents [15].
At least two decapod crustaceans, the Pendulous shrimp Dichelopandaulus leptocerus and the American lobster Homarus americanus, showed diseases attributed to chytrid fungi [19,9]. In addition, chytrid fungi were found to parasitise the eggs of the prawn Alpheus saulcyi [18]. Accordingly, in the present study we suggest that a chytrid fungus was responsible for mortalities observed in pond culture of M. rosenbergii. A few reports sustain that fungi infections are related to disturbance of physicochemical parameters in aquaculture ecosystems, such as water temperature, pH, transparency, as well as the host density [20,12,3,4,13,7]. Our data have shown high values of alkalinity, hardness and ammonia concentration in the water of infected ponds (Table 1). Furthermore, the culture cycles were mostly practiced on a continuous basis without intermittent drying of the pond. Taken these data together, it is possible that a combination of factors might have created a suitable environment for Chytridiomycetes and increased susceptibility of the prawns to pathogens.
This is the first report of chytrid fungal infection in M. rosenbergii, but further studies on the ultrastructural, molecular, geographical and diagnostic aspects of this emerging fungal disease in India could provide valuable information for its control during freshwater prawn culture.
Acknowledgments
The authors would like to thank J Muthumary (Centre for Advance Study in Botany, University of Madras, India) and S Raghukumar (National Institute of Oceanography, India) for their help in identifying the chytrid fungi.
References
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Range Mean ± SDTransparency (cm) 20- 45 27.77 ± 5.84Dissolved oxygen (ppm) 0.9 – 8.1 4.04 ± 2.57Carbon dioxide (ppm) 4 -23 13.90 ± 5.84Turbidity 20 - 85 45.30 ± 21.74Total solids (ppm) 1122 – 1530 1349 ± 160.16Total hardness (ppm) 180 – 250 220 ± 26.17Chlorides (ppm) 380 – 490 446 ± 46.69Ammonical nitrogen (ppm) 0.22 – 1.12 0.43 ± 0.12Alkalinity (ppm) 290 - 372 341.40 ± 26.28Calcium (ppm) 24 - 32 29.80 ± 4.26Magnesium (ppm) 29 - 41 35.80 ± 5.49
Table 1: Water quality parameters in the culture ponds of M. rosenbergii affected by chytrid fungus.
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