Cannibalism during intermoult period in early stages of the Southern King Crab Lithodes santolla (Molina 1872): Effect of stage and predator-prey proportions

SOTELANO, M. PAULA; LOVRICH, GUSTAVO A.; CAROLINA ROMERO; TAPELLA, FEDERICO

JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY

ELSEVIER SCIENCE BV

Año: 2012 vol. 411 p. 52 - 58

0022-0981

The anomuran crab Lithodes santolla represents an important fishery resource in the southernmost part of the 22American continent, where populations are endangered by overexploitation. During first attempts of rearing, 23intraspecific predation was observed in early stages of L. santolla and may stand as a main source of mortality 24in cultures. Cannibalism (defined as the sum of injured and dead crabs) between larvae and juveniles of 25L. santolla was tested in five Predator–prey (P–p) stage combinations and three P–p proportions during the 26Q3 intermolt period. Intra-stage predation in Megalopae (M), crab stage 1 (C1) and crab stage 2 (C2) was similar 27between stages (~15%) and lower than inter-stage cannibalism. Difference in size of conspecifics was the 28main cause of cannibalism. Total consumption of prey after 3–5 days was observed when 1-year-old crabs 29(C1yo) encountered either zoeae 1 (Z1), M or C1. Cannibalismin the combination C2–C1 occurred immediately 30after experiments began. Contrastingly, in the combination C1–M cannibalism started after day 9 of the experi- 31ment, suggesting that the swimming ability of M is a key factor for predator avoidance. At the end of intermolt 32period cannibalismwas higher in C2–C1 than in C1–Mstage combination and reached 75% and 60% respectively. 33Directionality of attacks among crabs showed that bigger animals can cause severe damage to smaller ones and 34not vice versa. Injured predatorswere only observed in C1–Mstage combination and are likely the result of intra- 35stage cannibalism among C1 whenM remain unreachable. P–p proportions had an impact on cannibalism since 36themore unequal the P–p proportions, the higher the cannibalismin both C1–Mand C2–C1 stage combinations. 37Differential limb loss occurred in L. santolla since walking legs appeared more vulnerable than chelipeds. Al- 38though L. santolla showed high predation among conspecifics, cannibalismin early juvenile stages under natural 39conditions should be lower than in the present study, as density of cultures was high (~950 ind m 40 −2) and ourexperimental design provides no refuge/shelter to animals. Hence, the future challenge for massive culturing 41crabs will be the mitigation of cannibalism.