Effects of early visual experience on the background preference in juvenile cuttlefish Sepia pharaonis

Although cuttlefish are capable of showing diverse camouflage body patterns against a variety of background substrates, whether they show background preference when given a choice of substrates is not well known. In this study, we characterized the background choice of post-embryonic cuttlefish (Sepia pharaonis) and examined the effects of rearing visual environments on their background preferences. Different rearing backgrounds (enriched, uniformly grey and checkerboard) were used to raise cuttlefish from eggs or hatchlings, and four sets of two-background-choice experiments (differences in contrast, shape, size and side) were conducted at day 1 and weeks 4, 8 and 12 post-hatch. Cuttlefish reared in the enriched environment preferred high-contrast backgrounds at all post-embryonic stages. In comparison, those reared in the impoverished environments (uniformly grey and checkerboard) had either reversed or delayed high-contrast background preference. In addition, cuttlefish raised on the uniformly grey background, exposed to a checkerboard briefly (0.5 or 3 h) at week 4 and tested at week 8 showed increased high-contrast background preference. Interestingly, cuttlefish in the enriched group preferred an object size similar to their body size at day 1 and week 4, but changed this preference to smaller objects at week 12. These results suggest that high-contrast backgrounds may be more adaptive for juvenile cuttlefish, and visually enriched environments are important for the development of these background preference behaviours.     

Combined effects of photoperiod and feeding frequency on survival and growth of juvenile cuttlefish Sepia officinalis L. in experimental rearing

The combined effects of photoperiod and feeding frequency on survival and growth of juvenile cuttlefish has been studied in experimental rearing. During juvenile cuttlefish growth, survival and growth rate were low when the photoperiod was short (8 h of light and 16 h of dark). Increased frequency of diet did not stimulate the appetite of animals reared in normal or long photoperiod (16 h of light and 8 h of dark). However, by studying the combined effects of photoperiod and feeding frequency, we have demonstrated that an increase in feeding frequency can enhance survival and growth in the group receiving the shortest period of light per day. Temperature is an important factor in the regulation of the incubation period of eggs and of growth after hatching, but it also appears in this investigation that the combined effect of photoperiod and feeding frequency must be considered during growth of juvenile cuttlefish.     

Effects of lamb rearing conditions on aggression and dominance relationships

The effects of rearing conditions on agonistic behavior were studied using lambs reared: (1) in a flock; (2) individually with a ewe; (3) with other lambs; (4) as individuals. The lambs were paired in a noncompetitive situation preweaning, and again postweaning, after 10 weeks of cohabitation in one group; competitive paired tests were also conducted postweaning. During the preweaning paired tests, the socially deprived lambs exhibited play and investigatory behavior while the flock reared lambs ignored the other lambs or were aggressive. Neither the postweaning noncompetitive nor the competitive paired tests revealed disparity in behavior among treatments.     

Small-scale rearing of cuttlefish (Sepia officinalis) for research purposes

We report a methodology refined over 20 years to culture and maintain a small colony of Sepia officinalis for research year-round. Wild-caught eggs were obtained annually from England and reared in semi-closed natural seawater systems of large volume. Constant temperature (15 °C) and day length (12L/12D) delayed sexual maturation and reproductive behavior. This extended life cycle by roughly 50%, thus providing small research animals for about 18 months from every annual batch of eggs. A novel live food – gammarid crustaceans collected from washed up seagrass– was provided to hatchlings and juveniles. Juveniles were then trained to take thawed shrimp thereafter, thus reducing the expense of live foods. Typical survival to one year was >65%. With these methods, healthy sexually immature cuttlefish were available year-round for behavioral and physiological studies without the confounding influences of hormonally-induced fighting, mating, and egg laying that typically occur within six months.     

养殖密度对史氏鲟消化率、摄食率和生长的影响

以体重（43.90±1.75）g史氏鲟为研究对象,研究了0.525、1.171和2.138 kg·m^-2 3种养殖密度对史氏鲟幼鱼生长、摄食率和消化率的影响,实验时间为60 d.结果表明,养殖密度对史氏鲟的生长、摄食率和消化率具有显著影响.高养殖密度不利于史氏鲟的生长,低密度组中史氏鲟的特定生长率和日增重显著高于高密度组,食物转化率显著低于高密度组;特定生长率和日增重随养殖密度的降低而显著增高.低密度组、中密度组中史氏鲟的消化率无显著差异,但均显著高于高密度组.中密度组摄食率显著低于高密度组和低密度组,低密度组摄食率介于两者之间;食物转化率和消化率呈显著负相关,特定生长率与消化率呈显著正相关.     

饲养条件对黄粉虫幼虫生长及存活的影响

采用5因素2次正交旋转组合设计,以黄粉虫幼虫饲养过程中饲养温度(X1)、相对湿度(X2)、虫粪筛除频率(X3)、饲养密度(X4)以及饲料含水量(X5)5因素为参试因素,考查它们对黄粉虫高龄幼虫的生长及存活的影响,建立并进行了简化得到了以黄粉虫幼虫增重率及死亡率为目标函数的回归模型：Y增＝127．5079 18．6559x5 2．7894x3x4-2．3854x3x5-3．0594x1^2 1．824lx3^2-3．8559x5^2;y死＝1．7459 0．4l08x1 0．0975x2 0．9025x4 0．3442x5 0．0834x1^2 0．3060x4^2-0．2623x5^2。分析结果表明：影响黄粉虫幼虫生长后期增重及死亡的主要因素分别为饲料含水量和饲养密度;饲料含水量和温度对黄粉虫增重有着重要的影响,饲养密度、温度、饲料含水量对黄粉虫的死亡有着重要的影响,其影响均达1％或5％显著水平;推荐的饲养条件为：温度24—27℃、相对湿度64％一70％、筛粪频率2—4d／次、饲养密度0．42-0．49g／cm^2、饲料含水量l3．48％-l7．48％。     

Effects of salinity on physiological conditions in juvenile common snook Centropomus undecimalis

This study describes the effects of different salinities on oxygen consumption, ammonia excretion, osmotic pressure, apparent heat increment, postprandial nitrogen excretion, and oxygen:nitrogen ratio in juvenile common snook Centropomus undecimalis. Oxygen consumption of fish fasting and fish feeding was statistically different in relation with salinity. Fish maintained at 0, 25, and 35 ppt invested more energy processing feed than fish maintained at 12 ppt. Fasting fish had lower ammonia excretion than feeding fish and excretion was reduced at high salinities. Snook can change the energetic substrate in function with salinity, from a mixture of protein and lipids and carbohydrates at 35 ppt to a more acute preference for proteins at lower salinities. This species changes osmotic plasma concentrations at extreme experimental salinities. The different salinities were the snook inhabits (0-36 ppt), have a direct effect on the physiology, inducing changes on the oxygen consumption, nitrogen excretion, changes on the energetic substrate and plasma osmotic pressure.     

Individual growth and smoltification of juvenile masu salmon, Oncorhynchus masou Brevoort, under rearing conditions

In a reared population of individually marked juvenile masu salmon, individual growth was monitored from the first autumn in 1983 to the following spring. The potential smolts were not significantly greater in mean fork length and body weight than the potential parr in late August of the first year, but they then grew faster until March of the second year. As a result, the potential smolts formed the upper mode of the bimodal length distribution after February. Especially in autumn (October and November) the specific growth rates of potential smolts were significantly greater than those of parr, and the bimodality in growth rate distribution was more distinct for males than females. These suggest that there are two groups having different growth rates in autumn of the first year and that sufficient growth in this period may play an important role in smoltification in the following spring.     

Bimodal distribution of length of juvenile Atlantic salmon (Salmo salar L.) under artificial rearing conditions

In 52 populations of juvenile Atlantic Salmon, Salmo salar L., from 14 pairings of wild parents, reared at the Almondbank smolt rearing station between 1973 and 1976 in circular radial-flow tanks, bimodality in the frequency distribution of length and weight has been characteristic by the first autumn of growth, and has become progressively clearer during the following winter.
The examination of 13 populations showed the modes did not correspond to separate sexes, from four others it was shown they did not correspond to immature fish and precociously mature males. It is suggested that the two modes correspond to subpopulations smoltifying at ages ( t ) and ( t +1) years. The age-composition of the smolt-run originating from individual year-classes of salmon in four Scottish rivers was found to be consistent with stocks having size-group segregations, at the time of the first smolt emigration, similar to those found among Almondbank experimental material. It is inferred that bimodality of size distribution is the norm among sibling populations of juvenile Atlantic salmon.     

Effects of rearing conditions on natal dispersal processes in a long‐lived predator bird

Natal or prebreeding dispersal is a key driver of the functioning, dynamics, and evolution of populations. Conditions experienced by individuals during development, that is, rearing conditions, may have serious consequences for the multiple components that shape natal dispersal processes. Rearing conditions vary as a result of differences in parental and environmental quality, and it has been shown that favorable rearing conditions are beneficial for individuals throughout their lives. However, the long‐term consequences of rearing conditions on natal dispersal are still not fully understood in long‐lived birds. In this study, we aim to test the following hypotheses to address the relationship between rearing conditions and certain components of the natal dispersal process in Bonelli’s eagle (Aquila fasciata): (1) The body condition of nestlings depends on the quality of the territory and/or breeders; and (2) the survival until recruitment, (3) the age of recruitment, and (4) the natal dispersal distance (NDD) all depend on rearing conditions. As expected, nestlings reared in territories with high past productivity of chicks had better body condition, which indicates that both body condition and past productivity reflect the rearing conditions under which chicks are raised. In addition, chicks raised in territories with high past productivity and with good body condition had greater chances of surviving until recruitment. Furthermore, birds that have better condition recruit earlier, and males recruit at a younger age than females. At last, although females in good body condition exhibited higher NDD when they recruited at younger ages, this pattern was not observed in either older females or males. Overall, this study provides evidence that rearing conditions have important long‐term consequences in long‐lived birds. On the basis of our results, we advocate that conservation managers work actively in the promotion of actions aimed at improving the rearing conditions under which individuals develop in threatened populations.     

Effects of rearing conditions on the parasitism of Tetrastichus brontispae on its pupal host Octodonta nipae

Octodonta nipae (Maulik) (Coleoptera: Chrysomelidae) is currently a serious invasive pest of palm plants in southern China. Although previous studies reported that Tetrastichus brontispae Ferriere (Hymenoptera: Eulophidae) could successfully parasitize the pupae of O. nipae, little is known of the potential for T. brontispae to control this pest. To understand the interaction between T. brontispae and O. nipae, the effects of parasitoid feeding regimes, host age and density, parasitoid age and density, and cold storage on the parasitism of T. brontispae were investigated. Our results indicate that a supply of either glucose or sucrose increased the longevity and fecundity of T. brontispae. The parasitoid preferred one-day-old host pupae and its fecundity increased with increasing host or parasitoid female density. Extended cold storage negatively affected the parasitism of T. brontispae. These results demonstrate how to efficiently raise T. brontispae and will contribute to the effective management of O. nipae.     

Coordination between the legs and tail during digging and swimming in sand crabs

Rhythmic leg movements and tailflipping are mutually exclusive behaviours in most decapod crustaceans, but sand crabs (Anomura: Hippoidea) combine leg movements with simultaneous tailflipping or uropod beating for both digging and swimming. We examined the coordination between the legs and tail (abdomen and tailfan) of Blepharipoda occidentalis, Lepidopa californica (Albuneidae), and Emerita analoga (Hippidae). When either albuneid swims, the tail cycles at a higher frequency than the legs, and the two rhythms are not coupled. When albuneids begin digging, the tail's frequency drops to that of the legs, and its rhythm becomes phase coupled to the legs. In E. analoga the legs seldom move during swimming by uropod beating. During digging the frequency of the uropods and fourth legs starts at about double that of the second and third legs, but drops to that of the second and third legs as digging progresses. The fourth legs in E. analoga are coupled with the uropods; their outward movement (= power stroke) is concurrent with the uropod return stroke. The familial differences in leg coordination and in the coordination of the legs and tail account for the smooth descent of E. analoga beneath sand compared to the stepwise descent of the albuneids. Accepted: 23 August 1996     

Effects of endogenous rhythms and light conditions on foraging and predator-avoidance in juvenile plaice

The influences of a light: dark cycle and a persistent endogenous rhythm of activity on foraging (on the bivalve Donax vittatus ) and avoiding a predator (juvenile cod, Gadus morhua ) were investigated in freshly-caught juvenile plaice, Pleuronectes plalessa . Time lapse video recordings were made of fish in the presence and absence of prey and predators in laboratory tanks over 24-hour periods between the times of successive daytime low waters. Endogenous rhythms of activity were seen in all experimental treatments. Swimming both close to the bottom and in the water column showed a strong circatidal rhythm, with most activity 2 to 3 h after the predicted time of high water. Swimming in the water column was more frequent at night than by day. In the presence of a population of Donax , whose siphon tips could be eaten as food, swimming close to the bottom became more frequent. This increase in benthic swimming was independent of the endogenous cycle of activity and was correlated with the frequency of attacks on siphons. The presence of the cod predator delayed the onset of foraging activity, producing a foraging/predator avoidance trade-off. The independence of foraging from light and endogenous rhythms suggests that this trade-off may be similarly independent. The cod also greatly reduced swimming in the water column in darkness, behaviour apparently unrelated to foraging.     

Behavioural responses of juvenile cuttlefish (Sepia officinalis) to local water movements

Physiological studies have shown that the epidermal head and arm lines in cephalopods are a mechanoreceptive system that is similar to the fish and amphibian lateral lines (Budelmann BU, Bleckmann H. 1988. A lateral line analogue in cephalopods: Water waves generate microphonic potentials in the epidermal head lines of Sepia officinalis and Lolliguncula brevis. J. Comp. Physiol. A 164:1-5.); however, the biological significance of the epidermal lines remains unclear. To test whether cuttlefish show behavioural responses to local water movements, juvenile Sepia officinalis were exposed to local sinusoidal water movements of different frequencies (0.01-1000 Hz) produced by a vibrating sphere. Five behavioural responses were recorded: body pattern changing, moving, burrowing, orienting, and swimming. Cuttlefish responded to a wide range of frequencies (20-600 Hz), but not to all of the frequencies tested within that range. No habituation to repeated stimuli was seen. Results indicate that cuttlefish can detect local water movements (most likely with the epidermal head and arm lines) and are able to integrate that information into behavioural responses.     

Effects of individual pre-fledging traits and environmental conditions on return patterns in juvenile king penguins

Despite the importance of early life stages in individuals' life history and population dynamics, very few studies have focused on the constraints to which these juvenile traits are subjected. Based on 10 years of automatic monitoring of over 2500 individuals, we present the first study on the effects of environmental conditions and individual pre-fledging traits on the post-fledging return of non-banded king penguins to their natal colony. Juvenile king penguins returned exclusively within one of the three austral summers following their departure. A key finding is that return rates (range 68-87%) were much higher than previously assumed for this species, importantly meaning that juvenile survival is very close to that of adults. Such high figures suggest little juvenile dispersal, and selection occurring mostly prior to fledging in king penguins. Pre-fledging conditions had a strong quadratic impact on juvenile return rates. As expected, cohorts reared under very unfavourable years (as inferred by the breeding success of the colony) exhibited low return rates but surprisingly, so did those fledged under very favourable conditions. Juvenile sojourns away from the colony were shorter under warm conditions and subsequent return rates higher, suggesting a positive effect of climate warming. The longer the post-fledging trip (1, 2 or 3 years), the earlier in the summer birds returned to their natal colony and the longer they stayed before leaving for the winter journey. The presence of juveniles in the colony was more than twice the duration required for moulting purposes, yet none attempted breeding in the year of their first return. Juvenile presence in the colony may be important for acquiring knowledge on the social and physical colonial environment and may play an important part in the learning process of mating behaviour. Further studies are required to investigate its potential implications on other life-history traits such as recruitment age.     

Effect of rearing temperature on sex ratio in juvenile Atlantic halibut, Hippoglossus hippoglossus

Several flatfish species exhibit temperature-dependent sex determination. This research investigated the effects of rearing temperature on sex ratio in Atlantic halibut, Hippoglossus hippoglossus, a species in which females grow larger and faster than males under culture conditions. Previous research has shown that ovarian differentiation occurs in Atlantic halibut in the size interval of 38–50 mm, and precedes the differentiation of testes. In the current study, triplicate groups of juvenile Atlantic halibut were reared at each of three temperatures (7, 12 and 15°C) from an initial mean size of 21 mm to a final mean size of 80 mm (total length). The sex of each fish was then determined by macroscopic and histological examination of the gonads. Sex ratios were not significantly different from 1:1 in any group, suggesting that sex in this species is not influenced by temperature.     

Effects of early rearing conditions on problem‐solving skill in captive male chimpanzees (Pan troglodytes)

Early rearing conditions of captive chimpanzees characterize behavioral differences in tool use, response to novelty, and sexual and maternal competence later in life. Restricted rearing conditions during early life hinder the acquisition and execution of such behaviors, which characterize the daily life of animals. This study examined whether rearing conditions affect adult male chimpanzees' behavior skills used for solving a problem with acquired locomotion behavior. Subjects were 13 male residents of the Chimpanzee Sanctuary Uto: 5 wild‐born and 8 captive‐born. A pretest assessed bed building and tool use abilities to verify behavioral differences between wild‐ and captive‐born subjects, as earlier reports have described. Second, a banana‐access test was conducted to investigate the problem‐solving ability of climbing a bamboo pillar for accessing a banana, which might be the most efficient food access strategy for this setting. The test was repeated in a social setting. Results show that wild‐born subjects were better able than captive‐born subjects to use the provided materials for bed building and tool use. Results of the banana‐access test show that wild‐born subjects more frequently used a bamboo pillar for obtaining a banana with an efficient strategy than captive‐born subjects did. Of the eight captive‐born subjects, six avoided the bamboo pillars to get a banana and instead used, sometimes in a roundabout way, an iron pillar or fence. Results consistently underscored the adaptive and sophisticated skills of wild‐born male chimpanzees in problem‐solving tasks. The rearing conditions affected both the behavior acquisition and the execution of behaviors that had already been acquired. Am. J. Primatol. 72:626–633, 2010. © 2010 Wiley‐Liss, Inc.