Influence of food abundance on competitive aggression in juvenile convict cichlids

2002 ◽  
Vol 63 (2) ◽  
pp. 323-330 ◽  
Author(s):  
James W.A. Grant ◽  
Isabelle L. Girard ◽  
Cindy Breau ◽  
Laura K. Weir
Keyword(s):  
Food Abundance ◽  
Convict Cichlids ◽  
Influence Of Food

OPTIMAL TERRITORY SIZE IN THE CONVICT CICHLID

Behaviour ◽  
1999 ◽  
Vol 136 (10-11) ◽  
pp. 1347-1363 ◽  
Author(s):  
James W.A. Grant ◽  
Jason Praw
Keyword(s):  
Growth Rate ◽  
Social Stress ◽  
Patch Size ◽  
Growth Efficiency ◽  
Food Abundance ◽  
Territory Size ◽  
Initial Increase ◽  
Archocentrus Nigrofasciatus ◽  
Convict Cichlids ◽  
Intermediate Size

AbstractModels of optimal territory size are usually tested only by demonstrating that territory size is inversely related to food abundance or intruder number. The most fundamental predictions of the models, however, have rarely been tested: i.e. the fitness of the defender is a function of territory size and the optimal territory is one of intermediate size. We tested these predictions by measuring the growth rate of large convict cichlids (Archocentrus nigrofasciatus, formerly Cichlasoma nigrofasciatum) while defending food patches against smaller intruders over a 10-day period. Food patches differed in area by more than two orders of magnitude. We manipulated food abundance so that it increased with patch size in a decelerating way. As assumed, the realized benefits of defence (weight of food eaten by the defender) and the costs of defence (chase rate and chase radius) both increased in a decelerating way with increasing patch area. As predicted, the growth rate of the defender first increased and then decreased with increasing patch size. The initial increase in defender growth rate with increasing patch size was related to an increase in food eaten, but the decrease in growth rate for fish defending the largest patches was related to the costs of defence. Fish defending large patches had a low growth efficiency, apparently because of the social stress caused by intruders in their territories. Taken together, these results support the assumptions and predictions of optimal territory size models.

Effects of Parent and Offspring Food Rations On Parental Care in the Convict Cichlid Fish (Pisces, Cichlidae)

Behaviour ◽  
1994 ◽  
Vol 129 (1-2) ◽  
pp. 63-77 ◽  
Author(s):  
James D. Kieffer ◽  
Robert J. Lavery
Keyword(s):  
Parental Care ◽  
Environmental Conditions ◽  
Food Supply ◽  
Cichlid Fish ◽  
Food Abundance ◽  
Convict Cichlid ◽  
Cichlasoma Nigrofasciatum ◽  
Convict Cichlids ◽  
More Care

AbstractAnimals may provide more care for their young under certain environmental conditions. For instance, if food is plentiful parents may invest more in the current brood than if food is scarce, assuming that food abundance is correlated with parent and offspring condition. In this experiment, we manipulated food levels (low vs high) for both parents and offspring to determine if parental care is influenced by parental and/or offspring condition in the convict cichlid, Cichlasoma nigrofasciatum. Parents which were fed a higher ration gained weight, whereas parents fed a lower ration lost weight. Similarly, young which were fed a higher ration were significantly larger than young fed a lower ration. Parents which were fed a higher ration defended their brood more vigorously than parents fed a lower ration. Offspring condition had little effect on parental care. Furthermore, females consistently invested more than males. The results show that parental convict cichlids adjust care in response to their own food supply rather than that of their offspring.

Food and foraging behavior in relation to microhabitat use and survival of age-0 Atlantic salmon

1998 ◽  
Vol 55 (1) ◽  
pp. 116-127 ◽  
Author(s):  
Keith H Nislow ◽  
Carol Folt ◽  
Marco Seandel
Keyword(s):  
Atlantic Salmon ◽  
Foraging Behavior ◽  
High Velocity ◽  
Field Experiments ◽  
Growth Period ◽  
Food Abundance ◽  
Invertebrate Drift ◽  
Microhabitat Use ◽  
Growth And Survival ◽  
Influence Of Food

We examined, using underwater snorkeling observations and field experiments, the influence of food availability on foraging behavior, habitat use, and survival of age-0 Atlantic salmon (Salmo salar) during the critical first-summer growth period. While most feeding attempts were directed at drifting invertebrate prey, we found a higher rate of benthic feeding forays than previously reported for salmon. Greater food abundance was associated with higher feeding foray rates, more time allocated to foraging, occupancy of higher microhabitat velocities, and greater first-year survival between two study streams. Experimental drift reduction reduced drift foray rates and triggered a change in behavior to increased benthic feeding. In contrast, within a single stream, greater predicted invertebrate drift in high-velocity microhabitats (1 m2) was unrelated to either microhabitat occupancy or drift foray rates of age-0 salmon. We suggest that, in some situations, salmonid foraging is related more directly to overall prey density than to the availability of high-velocity, high drift rate microhabitats. Differences in resource tracking (increased foraging, growth, or survival with increased food abundance) at different scales, along with the use of alternative predation modes, underscore the importance of considering behavior when linking food resources to growth and survival of stream salmonids.

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