QUANTITATIVE AND QUALITATIVE GUT CONTENT ANALYSIS OF MACROBRACHIUM ASSAMENSE PENINSULARE FROM RAWASAN STREAM OF GARHWAL HIMALAYA, UTTARAKHAND, INDIA

Koshal Kumar 1 , C. B. Kotnala 1 and Anita Rawat Rana 2 . 1. Department of Zoology, Campus Pauri, H.N.B Garhwal (A Central University) Uttarakhand India-246001. 2. Department of Zoology, Govt. P.G. (Autonomous) College Rishikesh, Uttarakhand India-249202. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


Materials and Methods:-
To understand the food intake of Macrobrachium assamense peninsulare the qualitative and quantitative analysis of gut contents were made on monthly basis for an interval of two years (2013)(2014)(2015). For this study 10 male and female were fixed in 70% alcohol soon after their capture, in order to stop the digestion of food in the alimentary canal (Williams, 1981) and brought to the laboratory for further analysis. In the laboratory before processing for the microscopic examination of the food contents, total weight of the individual intact prawn and that of its gut contents were recorded separately. In each specimen the carapace was opened from the dorsal side of the body and gut was removed carefully. A visual examination of fullness of intestinal bulb was also made immediately after its removal (Devi et al., 2013). The microscopic analysis was carried out as hurriedly as possible and was never overdue from more than 4 day after capturing the animal.

Analysis of Gut contents:-
In prawn, the food which reaches the gut is very fine crushed and is meshed due to the presence of powerful mandible. It is further churned in the mill itself and thus, the food items were identified up to the level which was possible. Different type of food item and their percentage was calculated on the basis of fractional analysis, by taking 1 ml of well shaken and thoroughly mixing stomach content suspension from petri dish into the Sedgewick rafter chamber and examined under binocular microscope to obtain percentage composition of different food items. Various food items were examined using binocular microscope and identified to the lowest possible taxonomical level with the help of keys and photographs provided by Ward and Whipple (1959); Needham and Needham (1962) and (APHA, 2012). The quantitative analysis was made and point was given purely on the basis of observation of food items.

Observations:-Food and feeding habits:-
The mode of feeding in Macrobrachium assamense peninsulare was observed visually in the field during the study. It was observed that prawn, by habit is an omnivorous species and exhibits feeding activity in day time in comparison to the other species. These prawns are also shy in nature and hide them self in their micro habitats and found under the stones, crevices near the bank of the stagnant water during study.
Quantitative study:-Monthly visual observation was also made and recorded the degree of fullness (%) of gut in Macrobrachium assamense peninsulare (Table 2). It is clearly proved that fullness of gastric content is directly related with seasonal variation and 100% fullness of gastric content was never observed during the study period of two years. Quantitative analyses revealed less than 6% population as empty stomach, 59.8% of stomach as actively fed including, 100%, 75% and 50% diet contents and poorly fed having 40.9% of stomach including, trace, empty and 25% gut content.
Qualitative study:-On the basis of microscopic examination of the gastric content, food was identified and categorized into seven groups viz., those containing fragments of aquatic plants, algae, animal matter, diatoms, sand grains and unidentified organisms. Different food items percentage in male and female prawn shown in Fig 1 (a & b). Composition of gut contents of Macrobrachium assamense peninsulare in relation to size groups were presented in the Table 1. During the observation no sex related trend with relation to different food types was observed. During the microscopic observation in the laboratory several food items identified from gut contents were recorded as. animal. These were observed in the gut throughout the study periods and dominated in the size group of 20-30 mm body length prawn and ranked fifth among the food items in male (6% ) and sixth (4%) in female. f. Amorphous mass: Amorphous mass or unidentified debris comprised of fragments of decomposing organic matter which could not be accurately identified due to their tiny size and poor physical appearance. This types of food items showed the dominance in gut content, i.e. male (44%) and female (41%) in Macrobrachium assamense peninsulare and was recorded maximum in 20-30 mm size group in male (43.2% ) in male and (41%) in female individual. g. Sand grains: Sand grains were found in inadequate percentage 1-2% in the gut of both sexes throughout the study. This item was possibly an accidental inclusion along with other food items, even though M. a. peninsulare is bottom feeder were mostly prefer dead and decay matter.

Discussions:-
Diet of Macrobrachium assamense peninsulare is generally microscopic, containing minute animal and plant matter showing its omnivorous nature. It is evident from gut content analysis that the organic detritus (unidentified debris) appears quite regular in the diet of the Macrobrachium assamense peninsulare (Table 1) throughout the study period in different size groups although its efficacy as food source seen to be important to grown-up prawns when it leads to benthic existence. Organic detritus was readily consumed when the other preferred food items were less available. Gut content of Macrobrachium assamense peninsulare consisted of fragments of aquatic plants, fragments of aquatic animals, algae, diatoms, amorphous mass, sand grains and unidentified organisms, which represented different trophic level. All types of food item were observed throughout the study period in variable proportion. In comparison to the observation of Subramanyam (1963a) and in agreement with Gopalkrishnan (1952), neither the size nor the sex had any relationship with the feeding habits of the prawn and the similar observation was observed in our study in Rawasan prawn. Present study was also comparable with the finding of Lee et al. (1992) analysis from gut contents of shrimp Lucifer faxoni. Dall (1968) had reported that the gut contents of various penaeid shrimps i.e. M. accleayi, P. plebejus, P. osculentes and P. merguiensis were mainly comprised of animal body parts (Jaw, legs, chitin fragments and seta) and some unidentified matters. Panikker (1952) reported food of young penaeid as of tiny organism, alga and detritus. Animals are classified as herbivorous, omnivorous and carnivores on the base of food type they eat (Chopra, 1939). Presence of fish scale by accidental entry along with detritus was observed in the gut content of M. rosenbergii (Raman, 1967) and M. equidens (Murthy & Rajagopal, 1990), whereas as no such material were reported from the gut contents of the Macrobrachium assamense peninsulare during the study.

Rao (1967)
reported that the M. rosenbergii eat up their exuvia after molting and Natraj (1947) also made similar observation in P. idea. During present study, we also observed M. assamense peninsulare by eating exuvia during the laboratory inspection in aquarium and sometime in the field observation. Murthy and Rajagopal (1990) recorded that in M. equidens the most of the food items consist of crustacean appendages, some parts of decay organic matter, sand and mud similar observations were recorded in our study.

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The percentage of empty stomach showed an increasing trend in M. assamense peninsulare toward the end of the onset of the breeding season and it was due to the less food intake by female prawn due to gonadal maturation, which occupy major portion of the cephalothorax and this is well compared with the studies of M. malcolmsoni Ibrahim (1962) where in a reduced feeding was noticed in mature female.