THE STUDY OF ECTOPARASITES ON BLUE SWIMMING CRAB, Portunus

pelagicus

*Muhamad-Fuad, M.A., **Shaharom-Harisson, F., **Ikhwanuddin, M.A. and **Ihwan, M.Z., 2009.

*Faculty of Maritime Studies and Marine Science, Universiti Malaysia Terengganu.**Institute of Tropical Aquaculture, Universiti Malaysia Terengganu.

Correspodence e-mail : ihwanz@umt.edu.my

Asian Pacific Aquaculture Conference 2009Putra Trade World Centre (PWTC)

6th November 2009

Parasitism is a type of association between two organisms, but one, the parasite, is dependent on and lives at the expense of other, the host.

(Caullery, 1952)

The host provides the environment in which the parasite lives.

Divided into two categories 1.Ectoparasites 2.Endoparasites

Parasites act as ectosymbiont or ectocommensal but become pathogenic and cause harm to their host in large number. (Klause Rohde, 1991)

Infected crabs are lethargic, susceptible to stress-induced mortality (e.g., capture, and handling), and often show signs of tremors or paralysis, or even blindness (CBV). (Newman & Ward, 1973; Couch, 1983)

To identify the ectoparasites located on the blue swimming crab, P.pelagicus

To study the morphological and attachment of the parasite

The taxonomy of the Blue Swimming Crab can be referred below:

Kingdom : AnimaliaPhylum : ArthropodaSubphylum : CrustaceaClass : MalacostracaOrder : DecapodaFamily : PortunidaeGenus : PortunusSpecies : Portunus pelagicus

Reasons of movement of P. pelagicus in and out of estuaries into the open ocean occurs

▪ for spawning ▪ reaction to lowered salinities.

(Meagher 1971, Potter et al. 1983, 1998)

Swimming is accomplished by sculling the oar-like fifth pair of legs, the swimming legs.

The male has a T-shaped abdomen that is held tightly against the body until maturity when it becomes somewhat free.

The immature female has a triangle-shaped abdomen that is tightly sealed against the body.

The mature female’s abdomen becomes rounded and can be easily pulled away from the body after the final molt.

Life cycle is dependent on estuaries as the larvae and early juveniles use these habitats for growth and development.

Females mate only during the final molt when they are in the soft shell condition, but males are believed to mate several times.

The male courting response is triggered by a pheromone released by the female. (Meagher 1971)

The smallest crabs shed every 3 to 5 days, juvenile crabs every 10 to 14 days and those 3 inches and larger every 20 to 50 days.

Five to 10 days before molting, a narrow white line appears just within the thin margin of the last two joints of the swimming legs.

A few days before shedding, the peeler crab’s narrow white lines give way to a red line, and fine white wrinkles appear on the blue skin between the wrist and upper arm.

The actual molting lasts for only a few minutes as the crab pushes out the rear of th ld h ll

Blue swimmer crabs are opportunistic, bottom feeding carnivores and scavengers. They are most active in foraging and feeding at sunset . (Grove-Jones 1987, Smith and Sumpton 1987, Wassenberg and Hill 1987)

Their diet chiefly consists of a variety of sessile and slow-moving invertebrates, including bivalve molluscs, crustaceans, polychaete worms and brittle stars.

(Patel et al. 1979,Williams 1982, Edgar 1990)

Fouling disease: Dirty, bad or unpleasant condition and

can cause blocking and immaturity. Algae encrusting: Algae encrust on the body or the gill

Gill commensalism: Stalked barnacles or other organism

blocking the gaseous exchange on the gill.

Cotton crab disease: The microsporan Ameson michaelis causes

severe muscle lysis. Pepper spot disease: An unusual condition brought about by a

hyperparasitic protozoan, Urosporidium crescens that infects the trematode Microphallus bassodactylus.

Gray crab disease: Caused by an amoeba, Paramoeba perniciosa

that invades the connective tissues, and hemolymph of crabs.

The crabs were collected from nearby fisherman at Tok Bali, Kelantan.

The crabs were kept alive in polystyrene box for analysis in the lab.

32 crabs consist of 16 male crabs and 16 female crabs were collected.

The crabs that will be used must reach its maturity for better results.

For females, the size carapace maturity is about 9.5 cm carapace width while male is about 8.5 cm carapace width.

Parasites collection

Observation were done on the surface of the shell, carapace, and the appendages

Any epibiota and other organism were collected by using scrapper and fixation were referred to epibiota fixation method

The shell were opened and the gills of the crab were observed

The surface of the gill filaments were scrape and the mucous of the scrape were placed in the glass slide and observed in under the microscope

For nematodes, the nematodes are picking by pointed needle and placed into the cavity block. The parasites were washed several times by distilled water

For protozoan parasites, the parasites are been observed and draw.

The epibiota were placed into 70% alcohol and been kept in glass bottle

The worms are put in Berlaind’s fluid for relaxing and straightening the worm. Then, the worm were added into 70% alcohol

For crustacean parasites, the parasites are collected and been fix in 70% alcoholShaharom-Harisson, 2008

PRESERVATION OF THE SAMPLES

For protozoan parasites, the slides containing the parasites were air dry

For nematodes, no staining is required.

For crustacean parasites, the parasites are taken out from the alcohol and placed it in a few drops of glycerine jelly.

For epibiota, no staining is required. The epibiota is simply being observed and draw.

The slides are then fixed with methanol and stain with giemsia liquid in the ratio 1:1

The worms are taken out from the alcohol and placed it on glass slides. The worm are placed with a few drops of lactophenol blue, covered with cover

slip and examined under microscope

The mount were covered by cover slip and the edges of the cover slip sealed with nail varnish to make permanent mount

Shaharom-Harisson, 2008

No Carapace Width(cm)Body

Weight (g) Octolasmis spp Cyprid larvae of Octolasmis spp Rhynchocoela worm Maturity

1 14.234 248.64 70 4 0 Mature

2 14.550 254.58 8 7 0 Mature

3 15.442 294.12 104 68 0 Mature

4 15.402 294.30 67 12 0 Mature

5 14.608 281.75 141 25 0 Mature

6 14.724 245.77 34 27 0 Mature

7 14.756 257.37 117 15 0 Mature

8 15.516 208.96 5 40 0 Mature

9 14.488 270.29 51 7 0 Mature

10 15.179 291.71 25 69 0 Mature

11 14.478 233.39 9 56 3 Mature

12 14.406 217.69 58 4 0 Mature

13 16.575 334.44 47 34 0 Mature

14 15.318 297.15 152 0 0 Mature

15 15.980 310.00 50 0 0 Mature

16 16.000 400.00 535 6 0 Mature

Total 1473 374 3

Max 535 69 3

Min 5 0 0

Std dev 122.51 22.95 0.73

Mean 92.06 23.38 0.19

Table 4.1 : Table show the data of the parasites collected on the male crabs,P.pelagicus

The mean number of individual of the Octolasmis spp per crab are 92.06 + 122.51( range: 5-535,n=16)

The mean number of individual of the cyprid larvae per crab are 23.38 + 22.95(range:0-69,n=16)

The mean number of individual of the Rhynchocoela worm per crab are 0.19 + 0.73(range : 0-3,n=16)

•Crab sample 16 show highest individual number of Octolasmis spp.

Figure 4.1: Figure show the graph for the number of parasites per individual in male crabs,P.pelagicus

Crab sample 14 and 15 show only Octolasmis spp inhabit the gill.Crab sample 8 and sample 11 show majorities of cyprid larvae individuals.

Figure 4.2: Figure show the percentage of parasites per individual for male crabs,P.pelagicus

NoCarapacewidth(cm) Body Weight (g) Octolasmis spp

Cyprid larvae of Octolasmis spp Rhynchocoela worm Maturity Berried female

1 15.430 268.00 226 4 0 mature No

2 14.140 211.72 150 3 5 mature No

3 14.905 212.03 375 0 7 mature No

4 14.133 208.20 246 0 2 mature No

5 14.300 228.78 106 1 51 mature No

6 14.338 207.53 48 11 24 mature No

7 16.002 256.67 29 17 18 mature No

8 14.152 218.82 83 6 11 mature No

9 15.248 259.62 191 21 128 mature No

10 14.402 216.31 74 4 42 mature No

11 15.000 221.30 70 33 33 mature No

12 15.300 250.04 115 18 42 mature No

13 14.674 190.09 34 33 12 mature No

14 14.200 224.88 56 4 0 mature No

15 13.902 219.91 117 33 0 mature Yes. Dark Color

16 14.402 250.80 111 10 0 mature Yes. Yellow Color

Total 2031 198 375

Max 375 198 128

Min 29 0 0

Std dev 89.64 11.69 31.68

Mean 126.94 12.38 23.44

Table 4.2: Table show the data of the parasites collected on the female crabs

The mean number of individual of the Octolasmis spp per crab are 126.94 + 89.64( range: 29-375,n=16)

The mean number of individual of the cyprid larvae per crab are 12.38 + 11.69(range:0-198,n=16)

The mean number of individual of the Rhynchocoela worm per crab are 23.44 + 31.68(range : 0-128,n=16)

• Crab sample 1 to 4 show higher percentage of Octolasmis sppindividual than other samples.•Sample 5 to 13 show higher percentage of Rhynchocoela worm than other samples.

Figure 4.3: Figure show the percentage of parasites per individual for female crab P.pelagicus

Figure 4.4: Figure show the number of parasites per individual for female crabs, P.pelagicus

Species of the genus Octolasmis are normally found in Eastern and Western warmer oceans in the Northern hemisphere, attached to crustacea, sea-snakes, etc. (Darwin, 1851)

Octolasmis spp are frequently found attached to many decapods crustaceans (Jeffries and Voris, 1996)

The cyprid larvae attach themselves to the exoskeleton of the host and filter feed on particulate matter transported through the host’s ventilatory system (Gannon, 1990)

As adults they are permanently attached to the host with the life cycle of the barnacle governed by the host’s intermoult period. (Jeffries and Voris 1996)

Reproductive success is dependent upon the barnacle reaching maturity before the host moults.

Thus to achieve reproductive success, a cyprid larva must select a host with a sufficient intermoult period to attach, metamorphose to adult form, oviposit and release nauplii . (Jeffries et al., 1992).

•The life cycle of Octolasmis species includes six nauplius (N1 -N6) and one cyprid larval stage.

•Larvae are in planktonic form and most of their life they feed continuously for the purpose of their development

• In cyprid stages, the larvae were now looking for suitable substrate for attachment. Figure 5.1: Figure show the life cycle of the stalked barnacles,

Octolasmis spp (picture taken from www.fieldmuseum.org)

Figure 5.2: Figure show the attachment of the cyprid larvae on the gill filament

Magnification: 10x10

The base of the peduncle is firmly attached, actually cemented, to the exoskeleton or gills depending upon the species.

Thus the barnacle is destined to remain attached at the site until the next molt of the host when the barnacles are sloughed off with the exuviae and probably are eaten along with the exuviae by scavengers.

The taxonomy of the Octolasmis spp is follow:

Kingdom : AnimaliaPhylum : ArthropodaClass : MaxillopodaOrder : PedunculataFamily : PoecilasmatidaeGenus : OctolasmisSpecies : Octolasmis spp

(Jeffries et al., 1992)

According to Gannon and Wheatly (1992), the barnacles cause physiological stress to the host.

Crabs with massive infestation did not survive the stress of experimental handling, and displayed a higher incidence of experimental mortality when subjected to aerial exposure and elevated temperatures.

Even thought the barnacles are known to be commensalism with the host, the effect of the competition within the gill chamber caused the crab to suffocated and eventually will die.

When the crab die, due to their cannibalistic habit, it helps the barnacle to produce and grow easily in the new host.

Barnacle can caused other stress which is overload of the body due to heavy infested of the barnacles itself.

The grower up population of the barnacle causing the weight of the crab is added more and influenced the movement of the crab.

The crab is stress due to heavy loaded and eventually will die.

Male crab consist more cyprid larvae than the female crab.

In mating season, the male crab will molt first than female.

After copulation, the female will molt later than usual.

The cyprid larvae attack the pre molt crab and embedded at the host.

Figure 5.3: Figure show the filter appendages of Octolasmis spp

Magnification: 10x10

Figure 5.4: Figure show the foot of Octolasmis spp for attachment

Magnification: 10x10

Figure 5.6: Figure show the Octolasmis spp attach on the gill filament.

Figure 5.5 : Red circle show the area of barnacle attachment (picture taken from Fox, 2001)

Figure 5.7 : Picture shows the area of barnacle attachment in the P. pelagicus. The samples were taken from Tanjung Dawai, Kedah.

Figure 5.8 : Picture shows that the barnacle that found in the crab’s gill. a) Anterior part of the barnacle; b) Attachment part of the barnacle; and c) Surface body of the barnacle. (Picture captured using Tabletop TM100 Microscope)

a) b) c)

Can also referred to as the Rhynchocoela, Nemertinea, Nemertina or Nemertini.

The general characteristics of the worm are:-

Bilaterally symmetrical and dorsoventrally flattened Body has more than two layers of cells with tissues and organs Body has a through gut with a mouth and anus Body has no body cavity Has a blood system with blood vessels Has a well developed nervous system Has an eversible and retractable ectodermal proboscis Reproduction is by asexual fragmentation, or sexual When it is normally gonochoristic, most species are carnivorous

and predatory

Female crab show higher abundance of the worm than male crab.

The nemertean worm infected the female by eating up the egg and just like barnacles; they share same characteristics of commensalism.

Other worm are carnivorous and predator which the worm eats egg that female berried it.

Distinguished by their having a long protrusible proboscis that is housed in a separate fluid filled cavity called the rhynchocoele.

The rhynchocoele is generally as long as the body and leads anteriorly to a short passage called the rhynchodaeum which open via the proboscis pore at the front end of the body.

Muscular body wall that includes both circular and longitudinal muscles.

Well developed blood system with two types of blood vessels but no heart, the blood vessels have valves and some have muscle layers that allow them to constrict thus causing the blood to flow.

Well developed nervous system with cephalic ganglia and a nerve network connecting various sensory organs.

Gut is basically a ciliated tube running from the mouth to the anus.

Mouth

Eye spotProboscis

Magnification:10x10

Figure 5.9: Figure show the head of nemertean worm

Two parasites were identified which is Octolasmis spp and Nemertean worm.

Female crabs are more infected by Octolasmis spp and Nemertean worm than the male crab.

Cyprid larvae are more abundance in male than female.

Both parasites that have been found are commensalism.

Octolasmis spp show no parasitic characteristic for embedded foot on the gills.

Octolasmis spp are filter feeder type feeding while Nemertean worm are carnivorous and predator with commensally type feeding which is take out the food from the host without harm it.

Infestation of Octolasmis spp caused stress to the host because the host have to compete with the barnacle for gaseous exchange.

Nemertean worm also caused stress to the host if there is large number of the worm infected and can cause egg mortality to the crab.

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