A note on a possible influence of traps on assessment of the diet of Jasus lalandii (H. Milne-Edwards).
نویسندگان
چکیده
Dietary analyses are important components of ecological studies. However, some methods of collecting organisms may expose them to exceptionally high densities of prey items, leading to inaccurate dietary assessments. These methods include the use of baited traps. We hypothesised that such a "trap effect" occurred during work on the diet of the rock lobster Jasus lalandii, because baited traps attracted isopods, which were then eaten opportunistically by trapped J. lalandii. To test this hypothesis, rock lobsters were collected at two sites using both baited-traps and Scuba diving. Results showed that large numbers of isopods were attracted to, and consumed, the trap-bait. Analyses of the stomach contents of trap-caught J. lalandii from both localities reflected a larger occurrence and significantly greater abundance of isopods in stomach samples from trap- rather than Scuba-caught rock lobsters. For probably similar reasons, small fish were significantly over-represented in the gut contents of trap-caught rock lobsters, although the evidence is less clear-cut and there may be other explanations for the high proportions of fish in the diet. Although isopods and fish may be naturally consumed at a low rate, predation on them is greatly inflated in traps, and the dietary analyses of trap-caught J. lalandii. All assessments of the diets of animals traditionally caught with traps should consider and account for such "trap effects", by calibrating the data for trap-caught animals against an alternative sampling method.
منابع مشابه
Reproductive biology of swimming crab, Charybdis hellerii (A. Milne-Edwards, 1867) in coastal waters of the Persian Gulf (Hormuzgan province)
This study was conducted to determine some aspects of reproductive biology of the Indo-Pacific swimming crab, Charybdis hellerii (A. Milne-Edwards, 1867) in coastal waters of the Persian Gulf (Hormozgan province) from June 2015 to May 2016. The results showed that the annual sex ratio is F: M=1:1.3, with 57.4 % males. All the five stages of ovarian development of C. hellerii were observed throu...
متن کاملبررسی پراکنش مکانی میگوی سفید Metapenaeus affinis (H. Milne-Edwards, 1837) در سواحل استان بوشهر با استفاده از ترال کف روب
این تحقیق با هدف بررسی پراکنش مکانی میگوی سفید سرتیز (Metapenaeus affinis) در سواحل استان بوشهر در فصل صید میگو (مرداد و شهریور 1392) انجام گردید عملیات نمونه‌برداری در سه طبقه عمقی کمتر از 10 متر، 20-10 متر و 30-20 متر انجام گرفت. در بررسی اثر عمق بر میزان صید به ازای واحد تلاش صیادی اختلاف معنی‌داری مشاهده شد (001/0Pp) و بزگترین میگوی صید شده میگوی ماده با اندازه 15 میلی‌متر بود. در بررسی نسب...
متن کاملA Note on Tensor Product of Graphs
Let $G$ and $H$ be graphs. The tensor product $Gotimes H$ of $G$ and $H$ has vertex set $V(Gotimes H)=V(G)times V(H)$ and edge set $E(Gotimes H)={(a,b)(c,d)| acin E(G):: and:: bdin E(H)}$. In this paper, some results on this product are obtained by which it is possible to compute the Wiener and Hyper Wiener indices of $K_n otimes G$.
متن کاملThe Origin and Developmerit of the Spermatophoric
THE PURPOSE OF THIS PAPER on the origin and development of the spermatophoric mass of Enoplometopus oeeidentalis (Randall) is threef~ld: (1) to increase our knowledge of the blOlogy of this little-known species, (2) to show evidence in suppott of external fertilization, an? (3) ~o extend the list of mechanically sperm-ltberatmg families in Hawaii to include t~eNephropsidae(Homaridaeauet., Nephr...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of experimental marine biology and ecology
دوره 247 2 شماره
صفحات -
تاریخ انتشار 2000