Stomach Contents of Sergestid Shrimp Acetes japonicus from the Estuary of Tanjung Dawai Peninsular Malaysia
The study on food and feeding habits of planktonic shrimp Acetes japonicus were done by examining the stomach contents of 164 specimens between June 2008 and May 2009. Samples were obtained from the bag net that was set along the bank of Tanjung Dawai estuary. Diet compositions of A. japonicus were grouped into eight major categories: phytoplankton, zooplankton, algae, appendages of crustacean, plant matter, debris, unidentifiable items and sand and mud. Analysis on the percentage of numerical abundance (Ci) showed that plant matter (28.18%) and crustacean appendages (18.70%) as the two highest values amongst the eight categories of food items. In addition, percentage frequency of occurrence (Fpi) values of phytoplankton, zooplankton, algae, plant matter, appendages of crustacean, debris, unidentified items and sand and mud were 3.54, 7.05, 5.07, 27.44, 17.42, 15.80, 8.94 and 19.81%, respectively. On the basis of food composition found in the stomach, it can be concluded that A. japonicus is omnivorous in feeding habit.
Received: August 30, 2011;
Accepted: November 21, 2011;
Published: December 30, 2011
Sergestid shrimp Acetes japonicus is regarded as an important component
of the marine zooplanktons in the coastal waters of the western coast of Peninsualr
Malaysia (Amin et al., 2009a). In term of distribution,
A. japonicus occurs in the shallow waters of a muddy bottom in the Indo-West
Pacific west coast of India to Korea, Japan, China, Indonesia (Omori,
1975) and reported to be present in the Straits of Malacca by Arshad
et al. (2007). Acetes has various uses in the preparation
of local delicacies. Besides being used as edible products and ingredients for
artificial fish feed formulation, they are also important ecologically as food
source for many marine fishes. They are known to feed on both phytoplankton
and zooplankton and form a natural highly balanced diet for the fish (Xiao
and Greenwood, 1993). There is no specific report available on the feeding
habits of A. japonicus although other biological aspects were earlier
reported by (Arshad et al., 2007, 2008;
Amin et al., 2009a, b,
2010a, b). The present study
has been undertaken to specifically examine the feeding habits of A. japonicus.
Thus, objective of the study was to determine the diet composition of A.
japonicus and to assess the temporal variation of diet composition over
a period of one year.
MATERIALS AND METHODS
Study area: Samples were collected monthly from the local fisherman of Tanjung Dawai (N 5° 40' 48" and E 100° 22' 5''), coastal waters (Fig. 1) between June 2008 and May 2009. However, it was not possible to collect any shrimp samples in November 2008 due to flood problem in the study area. The main fishing gear used by fishermen to catch acetates was the Set Bag Net (SBN). The net was normally set up during high tide and harvesting was done during the low tide. The SBN was fixed mostly between 2 and 3 m depth along the shallow waters in the upper estuary. The mesh size of the SBN was around 0.5 cm at cod end. Fresh samples for study were taken from fishermans net immediately after hauling and preserved in 5% formalin for laboratory analysis.
Stomach examination: Specimens were identified using a Nikon dissecting
microscope (Nikon-122764, Japan). A. japonicus was identified using the
reference of (Omori, 1975). A total of 330 stomachs (30
stomachs per month) of A. japonicus were analyzed but only 164 stomachs
were either full or half full or quarter full and the remaining 166 were empty
stomach. Each stomach was removed from the cephalothorax region using a pin
under a dissecting microscope (Omori, 1975). The stomach
contents were then incised and laid on a counter glass slide. A drop of distilled
water was added to the sample. Food items and frequency of occurrence were counted.
Food item identification was made using references by Crane
(1973), Lokman (1990), Lewis (1979)
and Bougis (1976).
||Geographical location of the study site in the Tanjung Dawai
(•), Kedah, Peninsular Malaysia
Stomach contents analysis: Percentage frequency of occurrence and percentage
numerical abundance methods (Chrisfi et al., 2007)
were adopted for the analysis of stomach content.
||Percentage frequency of occurrence (Fpi) = (N1i/Np)x100,
where N1i is the number of the stomachs in which food item i
was found and Np is the number of non-empty stomachs
||Percent numerical abundance:
where, ni is the number of ith food item and m the number of food items.
Diet composition: In total, 23 food items belonging to eight major groups were identified from the stomach sacs of A. japonicus. Percentage of diet composition in the stomach of A. japonicus is presented in Fig. 2. Plant matter consisted 27.81% of the total composition and was the highest proportion observed. The second highest value was the crustacean appendages (18.06%). This was followed by sand and mud (17.43), debris (14.4%), unidentified items (8.12%), phytoplankton (6.13%), zooplankton (6.05%) and algae (4.46%). Among the phytoplankton diet recorded, dinoflagellate (3.61%) was the most dominant. This was followed by diatom (1.89%), Navicula (1.7%), centric diatom (1%), Euglena (0.77%), Coscinodiscus (0.41%) and Ceratium (0.31%). As for the zooplankton (Table 1), copepod (2.08%) made up the highest percentage and this was followed by the amphipods (1.99%), cladocerans (1.71%), ostracods (1.43%) and mysids (0.92%) (Table 1).
Seasonal variation of prey items: Monthly percentage frequency of occurrence
(Fpi) of prey items are presented in Table 2. Phytoplankton
was found in every month of the stomach samples. Slightly higher frequency of
occurrence of phytoplankton was recorded in September (5.1%), January (6.9%),
March (5.5%), April (6.6%) and May (8.4%).
||Percentage of major groups of diet composition of A. japonicus
from the estuary of Tanjung Dawai, Kedah
|| Combined mean percentage of diet composition of A. japonicus
in the estuarine waters of Kedah
Among the phytoplankton composition, dinoflagellate, diatom and Naviculla
were consistently dominant throughout the year. Zooplankton was observed around
the year except in the month of July. The occurrence of zooplankton were particularly
higher during March (11.1%) and April (16.2%). Copepod and ostracod showed diverse
distribution throughout the year compared to other zooplankton. Algae were found
from April-July and September-December. Apart from these months, no algae diets
were found. Plant matter was found in most months of the year and its occurrence
frequency ranged from 5.4 to 32.8%. Appendages of crustacean and debris were
also recorded throughout the study period. The highest occurrence of plant matters
was observed during June to August. High occurrences of crustacean appendages
were found between October 2008 to February 2009. The highest percentage frequency
of debris was seen in February and this is similar to the highest percentage
frequency showed by the crustacean appendages (Fig. 3).
Percentage numerical abundance (Ci) of prey items is presented in
Table 3. High percentage of phytoplankton was recorded in
September (11.4%) and April to May (90%). Zooplankton was highest in March 2009
(16.6%). The lower number of zooplankton percentage was found between August
and December 2008. Algae abundance was highest in the month of July (12.32%).
Plant matter was found highest in June (30.2%) and lowest in September (5.9%).
Crustacean appendages ranged from 10.5 to 19.6%. No definite pattern on food
composition occurrence was observed. The percentage numerical abundance also
did not fully agree with the frequency of occurrence amongst the diets. In term
of numerical abundances, there were three major food components found in the
stomach in each month (Fig. 4). These were phytoplankton,
plant matters and crustacean appendages.
|| Percentage frequency of occurrence (Fpi) of food
items of A. japonicus in the coastal waters of Kedah
||Percentage frequency of occurrence (Fpi) of three
groups of diets in the different sampling months
The highest occurrences of phytoplankton were observed in September and in
January-May. The peak occurrences of plant matters were found in June-October
|| Percentage of numerical abundance (Ci)
of food items of A. japonicus in the coastal waters of Kedah
||Percentage numerical abundance (Ci) of three groups
of diets in the different sampling months
The peak occurrences of appendages of crustacean in the stomach were observed during the month of August- October and January-May (Fig. 4).
In the present study, diet compositions of A. japonicus were grouped
into eight major categories viz phytoplankton, zooplankton, algae, appendages
of crustacean, plant matter, debris, unidentified items and sand and mud. Amongst
all diets, plant matter showed the highest percent (27.81%). This is similar
in result with Amin et al. (2007) who found the
plant matter was also highest in the stomach of A. indicus from the
coastal waters of Malacca. Phytoplankton was the highest diet composition (45.51%)
in A. intermedius in the coastal waters of south-western Taiwan (Chiou
et al., 2005) and the dinoflagellate (27.03%) was also the most important
diet discovered. However, phytoplankton is not the major food item in the present
study. This could be attributed to the non specific food requirement characteristic
of this shrimp and the diversity in food source at different geographical location.
It is reported that A. paraguayensis grazing the phytoplankton group
such as Ankistrodemus sp., Oedogonium sp., Bulbochaeta
sp. and Navicula sp. (Collins and Williner, 2003).
This result in different main food items may be due to the different resource
availability in those places. It is reported by Zafar (2000)
that the stomachs of A. indicus in the coastal waters of Bangladesh contained
diatoms (30.08%), copepods (8.34%), sagitta (7%), foraminifera (1.66%), crustaceans
appendages (1.25%), detritus (27.5%), sand and mud (22.58%) and molluscan parts
(1.58%). Copepods were also recorded in the stomachs of A. japonicus
but no diatoms were found in the stomachs of A. japonicus collected in
the Ariake Sea (Ikematsu, 1957).
Deshmukh (2002) reported that detritus as the most
frequent food item (39.70%) in the stomachs of A. indicus in the coastal
waters of India. The foraminiferans, eggs and larvae were rare, whereas food
items commonly observed in the foreguts of shrimp such as polychaetes, molluscs,
filamentous algae and sand. It is concluded that the shrimp A. indicus
is omnivorous. Although detritus is not the major found items in the stomach
of A. japonicas but it is omnivores in the coastal waters of Tanjung
Dawai. Xiao and Greenwood (1993) had reported that copepods
were the primary item consumed by Acetes shrimp. The variety of food
ingested by A. japonicus indicates that they are omnivore, similar as
other species of Acetes (Xiao and Greenwood, 1993;
Xu, 1957). Based on the results obtained, it can be said
that A. japonicus is an active feeders and can be classified as omnivore
since it consumed food of both plants and animal origins.
According to combined mean percent of diet composition, plant matter was observed as the highest percentage 27.81% in the stomach of A. japonicus. This was followed by crustacean appendages 18.06%, sand and mud 17.43%, debris 14.4%, unidentified items 8.12%, phytoplankton 6.13%, zooplankton 6.05% and algae 4.46%. There was no definite pattern of food consumption between months and different peak of occurrence was observed. The various percentage composition of food items further reiterated that this shrimp species is a bottom feeder omnivore.
This study is part of a research project funded by the Ministry of Science, Technology and Innovation (MOSTI), Malaysia (grant No. 05-01-04-SF0613). The authors like to acknowledge MOSTI for providing financial funding to carry out present research work and UPM for the providing of the research facilities and technical assistance.
1: Amin, S.M.N., A. Arshad, S.S. Siraj and S.B. Japar, 2007. The biology and life history of sergestid shrimp Acetes indicus (Decapoda: Sergestidae) in the coastal waters of Malacca, Peninsular Malaysia. Bioscientist, 5: 9-17.
2: Amin, S.M.N., A. Arshad, S.S. Siraj and B.J. Sidik, 2009. Population structure, growth, mortality and yield per recruit of segestid shrimp, Acetes japonicus (Decapoda: Sergestidae) from the coastal waters of Malacca, Peninsular Malaysia. Indian J. Mar. Sci., 38: 57-68.
Direct Link |
3: Amin, S.M.N., A. Arshad, J.S. Bujang, S.S. Siraj and S. Goddard, 2009. Reproductive biology of the sergestid shrimp Acetes indicus (Decapoda: Sergestidae) in coastal waters of Malacca, Peninsular Malaysia. Zool. Stud., 48: 753-760.
Direct Link |
4: Amin, S.M.N., A. Arshad, S.S. Siraj and J.S. Bujang, 2010. Reproductive seasonality and maturation of the sergestid shrimp, Acetes japonicus (Decapoda: Sergestidae) in coastal waters of Malacca, Peninsular Malaysia. Afr. J. Biotechnol., 9: 7747-7752.
Direct Link |
5: Amin, S.M.N., A. Arshad, N.H. Ismail, M.H. Idris, J.S. Bujang and S.S. Siraj, 2010. Morphometric variation among the three species of genus Acetes (Decapoda: Sergestidae) in the coastal waters of Malacca, Peninsular Malaysia. Pertanika J. Trop. Agric. Sci., 33: 341-347.
Direct Link |
6: Arshad, A., S.M.N. Amin, S.S. Siraj and S.B. Japar, 2007. New distribution records of sergestid shrimp, Acetes intermedius (Decapoda: Sergestidae) from Peninsular Malaysia with notes on its population characteristics. J. Biol. Sci., 7: 1305-1313.
CrossRef | Direct Link |
7: Arshad, A., S.M.N. Amin, G.T. Yu, S.Y. Oh, J.S. Bujang and M.A. Ghaffar, 2008. Population characteristics, length-weight and length-length relationships of Acetes vulgaris (Decapoda: Sergestidae) in the coastal waters of Pontian, Johor, Peninsular Malaysia. J. Biol. Sci., 8: 1298-1303.
CrossRef | Direct Link |
8: Bougis, P., 1976. Marine Plankton Ecology. North-Holland Publishing Company, Amsterdam, Pages: 355
9: Chiou, W.D., J.J. Hwang, L.Z. Cheng and C.T. Chen, 2005. Food and feeding habit of Taiwan mauxia shrimp Acetes intermedius in the coastal waters of Southwestern Taiwan. Fish. Sci., 71: 361-366.
10: Chrisafi, P., P. Kaspiris and G. Katselis, 2007. Feeding habits of sand smelt (Atherina boyeri, Risso 1810) in Tichonis Lake (Western Greece). J. Applied Ichthyol., 23: 209-214.
11: Collins, P.A. and V. Williner, 2003. Feeding of Acetes paraguayensis (Nobili) (Decapoda: Sergistidae) from the Parana River, Argentina. Hydrobiologia, 493: 1-6.
12: Crane, J.M., 1973. Introduction to Marine Biology (A Laboratory Text). Merrill, Ohio, ISBN: 9780675089548, Pages: 179
13: Deshmukh, V.D., 2002. Biology of Acetes indicus milne edwards in Bombay waters. Indian J. Fish., 49: 379-388.
14: Ikematsu, W., 1957. An estimation of secular variation of Ami (Acetes japonicas and mysis) yield based on the past records of catch statistic in Saga prefecture. Rep. Invest. Ariake Sea, 88: 35-41.
15: Lewis, W.M., 1979. Zooplankton Community Analysis Studies on a Tropical System. Springer-Verlag, New York, USA., ISBN-10: 0387904344, pp: 10-21
16: Lokman, S., 1990. Marin Diatom in Malaysia. 1st Edn., Ministry of Education Malaysia, Malaysia, pp: 179-203
17: Omori, M., 1975. The systematics, biogeography and fishery of epipelagic shrimp shrimps of the genus Acetes (Crustacea, Decapoda, Sergestidae). Bull. Ocean Res. Inst. Univ. Tokyo, 7: 1-91.
18: Xiao, Y. and J.G. Greenwood, 1993. The biology of acetes (Crustacea: Sergestidae). Mar. Biol. Ann. Rev., 31: 259-444.
Direct Link |
19: Xu, C.Y., 1957. Studies on the diet composition of Acetes chinensis Hansen in Liaotung Bay: A survey of Acetes chinensis Hansen in Liaotung Bay, North China. Liaotung Marine Fisheries Laboratory, Liaotung, China, pp: 71-87.
20: Zafar, M., 2000. Study on sergestid shrimp acetes in the vicinity of mathamuhuri river confluence, Bangladesh. Ph.D. Thesis, University of Chittagong, Bangladesh.