Heart rate changes reveal that little blue penguin chicks (Eudyptula minor) can use vocal signatures to discriminate familiar from unfamiliar chicks

Researchers investigating social recognition typically measure only behavioural responses during discrimination tests - physiological changes have been largely ignored. We examined whether little blue penguin chicks (Eudyptula minor) could distinguish siblings from other chicks using auditory cues, by measuring behavioural and heart rate changes during playback experiments. Chicks were exposed to five treatments: the begging calls of siblings, neighbouring chicks and unfamiliar chicks, and two controls (heterospecific begging calls and music). We also determined if chicks developed distinctive begging calls, by using F-ratios to quantify inter- versus intra-individual variability in a range of acoustic parameters, and applying a discriminant-function analysis. Inter-individual variation was greater for pitch than for temporal or amplitude parameters, suggesting that call pitch may be important for individual recognition. The discriminant-function analysis showed each chick's calls were distinctive and could act as a vocal signature. Treatments did not instigate different behavioural responses. However, chick heart rates during playback of sibling calls were significantly higher than those recorded during stranger, but not neighbour, playback. A simple recognition system based on familiarity may allow this plesiomorphic and loosely colonial penguin to gain at least some of the benefits associated with more advanced sibling recognition systems (some highly colonial seabirds discriminate siblings from neighbouring chicks). Heart rate could be a useful measure of social recognition abilities, particularly in species where changes in behaviour are not always evident or are difficult to observe.     

External devices on penguins: how important is shape?

Many researchers use external recording or transmitting devices to elucidate the marine ecology of fish, mammals and birds. Deleterious effects of these instruments on the parameters researchers wish to measure are hardly ever discussed in the literature. Research has shown that, in penguins, volume and cross-sectional area of instruments negatively correlate with swimming speed. dive depth and breeding success, and that device colour affects bird behaviour. Here, a large (200 g, cross-sectional area 2100 mm²) streamlined device was attached to the lower back of Adélie penguins (Pygoscelis adeliae on Ardley Island, South Shetland Island in 1992) and its effects on bird swimming speed and energetics were measured in a water canal in Antarctica. Although the device was 10.5% of penguin cross-sectional area, swimming speed was reduced by only 8.3% and mean power input increased by only 5.6% while swimming. Although our streamlined device was five times more voluminous than one of our older units, the effect on swimming energetics could be reduced by 87%.     

The risks and benefits of signalling aggressive motivation: a study of cave-dwelling little blue penguins

Summary Cave-dwelling little blue penguins, Eudyptula minor, use a large repertoire of agonistic displays. Both qualitative and quantitative measures suggested that some displays were more dangerous to perform than others (estimated by the risk of being injured by one's opponent). A lag sequential analysis of interactions indicated a positive relationship between the risks of performing a display and the display's effectiveness (i.e., in deterring opponents). The cost or risk asymmetries that exist between displays may allow opponents to assess how motivated the actor is to secure or defend resources. Thus, high cost displays are more effective because they reveal a willingness to take risks and also place the opponent in a higher risk situation. Communicating in this way can be an evolutionarily stable strategy (ESS) because signalling a strong motivation entails using potentially costly behavior (i.e., there are costs associated with bluffing). Also, displays that were accompanied by calls were more effective in deterring opponents than the same displays performed silently. Calls may highlight the risks being taken by actors; this may be particularly important in nocturnal species like little blue penguins. Aggressive displays could also be used to predict what the actor was and was not likely to do following the performance of the display. Generally, aggressive displays predicted that the actor would escalate to a higher risk behavior if the opponent did not retreat, but that it would use a lower risk behavior if the opponent backed down. However, risk-based displays should be seen as revealing a certain level of motivation at the time of the display and not as a way of describing how great a risk the actor is willing to take following the display. The predictive value of displays appears to be the result of an escalation process which ensures that opponents are deterred by the lowest risk behavior possible.     

Satellite tracking of Humboldt penguins (Spheniscus humboldti) in northern Chile

During the El Niño of 1982/1983, the Humboldt penguin population diminished dramatically in the whole distributional area of the species. Recovery of the population was slow since 1983 and it has been suggested that large numbers of Humboldt penguins die at sea, entangled in nets, or starve to death, even during non-“El Niño” years. We were able to determine for the first time, how Humboldt penguins on Pan de Azúcar Island (26°S; 72°W) utilize their marine habitat and where their feeding areas lie. For this purpose we employed two streamlined Argos satellite transmitters during the 1994/1995 and 1995/1996 breeding seasons, respectively. Mean travelling speed of Humboldt penguins during foraging trips was 0.94?m s^?1 and 50% of bird positions were located within 5?km of the island (90% within 35?km). Total area covered by Humboldt penguins foraging from Pan de Azúcar Island was 12?255?km². Satellite transmitters also recorded dive duration; penguins spent on average 7.8 to 9?h diving per foraging day but showed no preferences for particular feeding areas. Mean daily dive durations (4-d mean) recorded during the 1994/1995 breeding season were positively correlated between birds. Significant correlation between dive duration and sea surface temperature anomalies and negative correlation between dive duration and fishery landings at nearby Caldera harbour indicate that the 1994/1995 increase in foraging effort was a response to deteriorating prey availability. Sea surface temperatures during the 1995/1996 breeding season were colder than average, and we observed no trends in bird diving activities.     

4,4'-二氨基二苯基甲烷对浮萍(Lemna minor L.)毒性作用

以浮萍(Lemna minor L.)为受试生物,通过研究不同浓度(0、0.6、1.8、5.4、16.2和48.6 mg·L-1)的4,4'-二氨基二苯基甲烷(4,4'-methylenedianiline,MDA)对浮萍生长、叶绿素含量、PSⅡ最大光化学效应(Fv/Fm)、质膜透性及超氧化物歧化酶(SOD)、过氧化物...     

Seasonal changes in the diving parameters of king penguins (Aptenodytes patagonicus)

Contrasting conditions at-sea are likely to affect the foraging behaviour of seabirds. However, the effect of season on the dive parameters of penguins is poorly known. We report here on an extensive study of the diving behaviour of king penguins (Aptenodytes patagonicus) over the bird's complete annual cycle at the Crozet Islands. Time-depth recorders were used to record dive duration, bottom duration, post-dive interval, ascent rate and descent rate in breeding adults during different seasons in 1995 and 1996. Seasons included summer (n=6, incubation; n=6, chick brooding), autumn and winter (n=5 and n=3, respectively, chick at the crèche stage), and spring (n=4, birds at the post-moult stage). In all seasons dive duration increased with dive depth, but, for a given depth, dives were longer in winter (6.8 min when averaged over the 100-210 m depth layer) than in spring (4.6 min) and summer (4.4 min). The time spent at the bottom of the dives, which probably represents a substantial part of the feeding time, was much longer in winter (2.5 min per dive for dives over the 100-210 m layer) than during other seasons (1.0-1.4 min), i.e. there was a 2.5-fold augmentation for similar diving depths. Ascent and descent rates increased with increasing dive depth, but no difference in the relationships between rates of ascent and descent and dive depth was found among seasons. Furthermore, for all dive depths, ascent and descent rates were independent of the bottom duration. In all seasons post-dive intervals increased with dive duration and with dive depth, but they were longer in spring (2.3 min for dives over the 100-210 m layer) and summer than in autumn and winter (1.6-1.8 min). The diving efficiency decreased with increasing dive depth and was higher in autumn and winter (0.22-0.29) than in summer and spring (0.15-0.18). The large increase in bottom and dive duration from spring to winter is in agreement with the seasonal drop in prey density, with penguins spending more time searching for prey. In contrast, the consistency of the vertical velocity during contrasting conditions at-sea suggests that the transit time to depth is an important component of the foraging behaviour (scanning of the water column) that is independent of the prey availability. The time budget of the penguins during diving in a fluctuating environment appears to vary primarily during the bottom phase of the dives, with bottom duration increasing with diminishing prey supplies, while post-dive intervals shorten in the same time.     

Evaluating the relative importance of intrinsic and extrinsic factors on the foraging activity of top predators: a case study on female little penguins

A complex interaction of biotic and abiotic factors influences animal foraging activity. It is often difficult to understand which factors may affect animals’ foraging and how it is affected. For instance, whereas the effect of sexual dimorphism on foraging activity has been reported in several species, little is known of the complex interactions between variables acting at a finer scale, e.g. the variability of body mass within a sex. Evaluating the importance of these finer scale factors is also essential to the understanding of foraging behaviour. We propose here a simple approach by applying principal component analysis (PCA) in a novel way to examine relationships between biotic and abiotic factors affecting foraging behaviour of top predators. We studied female little penguins (Eudyptula minor) of known age, carrying miniature accelerometers during the guard stage of breeding. Surprisingly, the body mass of the females did not influence any of the foraging parameters, but females foraging later in the breeding season dived shallower and more often, showing a strong correlation with laying date. Similarly, the diving effort of females was greater with increasing chick age within the same breeding stage. These results indicate that for female little penguin, the relationship between changes in prey availability and hunting effort can change at a fine scale, within a breeding stage. Therefore, any analysis of little penguin foraging behaviour during breeding should consider the timing in relation to the breeding season. We encourage researchers to develop the use of this PCA approach as it could help clarify the complexity of the underlying mechanisms determining foraging activity and we propose that it should be used as a first step of foraging behaviour analysis, before examining a particular relationship.     

Winter migration of magellanic penguins (Spheniscus magellanicus) from the southernmost distributional range

A total of 22 magellanic penguins (Spheniscus magellanicus) from Isla Martillo in the Beagle Channel, Argentina, were successfully satellite tracked in 2004 (n = 7), 2005 (n = 7) and 2006 (n = 8) to monitor their winter migration after moult. Only one magellanic penguin migrated northwards into the Pacific Ocean, whereas all others remained in the Atlantic Ocean. In general, these birds left the island in an easterly direction, rounded Cabo San Diego, the southeasterly tip of South America, and continued northwards occupying inshore waters mostly less than 50 km from the coast, only occasionally venturing further offshore. By the end of the transmission period, birds were still travelling northwards and the most northerly positions were obtained from birds located in the area of Peninsula Valdés, Argentina, at a latitude of around 42°S, some 1,500 km from their breeding site on Isla Martillo. The mean maximum distance to the breeding site was, however, only 624 ± 460 km. The mean minimum distance covered during the study period was 1,440 ± 685 km, which corresponded to a mean distance of 23.2 ± 6.6 km covered per day. The northbound migration of the penguins could be separated into periods of rapid movement, interspersed with periods during which the birds remained for some time in particular coastal regions. Areas with a high density of daily penguin positions were observed in three distinct areas: at the northeastern coast of Tierra del Fuego, at the southern entrance of Golfo San Jorge and to the northeast of the Peninsula Valdez. The observed migration pattern is presumably driven by the formation and subsequent dispersal of areas of enhanced productivity as the season progressed. Our findings also suggest that magellanic penguins are increasingly threatened by human activities in coastal areas as penguins migrate northwards.     

Diving characteristics of southern rockhopper penguins (Eudyptes c. chrysocome) in the southwest Atlantic

The diving behaviour of southern rockhopper penguins (Eudyptes c. chrysocome) was studied at two breeding sites in the Southwest Atlantic: the Falkland Islands and Staten Island, Argentina. Incubating and brooding birds were equipped with time-depth recorders to monitor their foraging activities. Rockhopper penguins from Staten Island started their breeding season about 3 weeks earlier than their conspecifics from the Falkland Islands. The foraging area used by incubating males from the Falkland Islands comprised about 150,000 km² to the northeast of the breeding site and was characterised by shelf and slope waters, whereas the foraging area of incubating males from Staten Island comprised 350,000 km² of oceanic waters to the southeast of the breeding site. A number of dive parameters were measured and compared between the four study groups: Incubating males and brooding females from the Falkland Islands, and incubating males and females from Staten Island. In all study groups, dive depth correlated positively to light intensity, dive duration and vertical velocity. However, significant differences between various diving parameters of the study groups were noted, not only in terms of diving performance, but also as regards diving efficiency (DE). A principal component analysis (PCA) on 16 variables revealed that 75% of the variance could be explained by only two principal components: diving pattern (PC1) and diving effort (PC2). PC1 indicated that the birds from Staten Island, both males and females, dived deeper, covered a greater vertical distance per hour and had higher ascent rates, but spent less time underwater and at the bottom of a dive, and had a lower DE than conspecifics from the Falkland Islands. PC2, which included the percentage of foraging dives, the number of dives per hour, dive duration, bottom time and descent rate, differed significantly between incubating males from the Falkland Islands and the other three groups, which were all very similar. Overall, the diving behaviour was notably similar to that of conspecifics from the Indian and Pacific Oceans. The implications of the results in terms of intra-specific adaptations as well as potential threats from human activities are discussed.     

Nestling size rank in the little egret (Egretta garzetta) influences subsequent breeding success of offspring

Few studies have investigated the long-term fitness consequences of nestling size hierarchies in altricial birds. In this study, we investigated whether or not the size rank order of siblings influences subsequent breeding success in the little egret, Egretta garzetta. From a marking program allowing individual recognition of wild birds, we obtained data on the breeding success of 56 pairs comprising individuals for which the size rank order was known. The breeding success in these pairs was positively influenced by the age of the marked bird but negatively affected by the laying date of the pair and the size rank order of the marked individual. There was also a significant difference between breeding colonies. We suggest two main hypotheses for a link between size rank order of individuals and their breeding success and we discuss our results in relation to current hypotheses on the adaptive value of hatching asynchrony. Received: 10 August 1998 / Accepted after revision: 13 December 1998     

Foraging behaviour and reproductive success in Magellanic penguins (Spheniscus magellanicus): a comparative study of two colonies in southern Chile

Marine Biology - During the breeding season 1996/97 we compared the foraging and diving behaviour of adult Magellanic penguins (Spheniscus magellanicus), growth rates of their chicks and their...     

Size-dependent behavior of tuna in an array of fish aggregating devices (FADs)

Several lines of evidence indicate that aggregations of yellowfin tuna associated with floating objects are more frequently composed of small animals than larger ones. Also, the diet of small yellowfin tuna caught at anchored fish aggregating devices (FADs) around Oahu, Hawaii, was found to shift quite rapidly when these fish reached approximately 50 cm FL. In order to test for ontogenetic changes in aggregation behavior, we tagged and released two distinct size classes of yellowfin tuna in an array of anchored FADs around Oahu, Hawaii. Twenty-four yellowfin tuna 30–39 cm FL and 16 yellowfin tuna 63–83 cm FL were tagged with acoustic transmitters and released near anchored FADs equipped with automated acoustic receivers. Fish in the smaller size class stayed about 2.5 times longer at individual FADs than the larger fish (mean 4.05 days vs. 1.65 days) and displayed larger horizontal movements within the array. However, the durations of unassociated phases, residence times in the entire FAD array, percentage of time spent associated with FADs and numbers of movements between FADs did not show any difference between the two size groups. The observed size-dependent behavior is discussed in terms of physiological abilities, diet segregation and anti-predator behavior.     

Toxicological evaluation of bacterial decolourised anaerobically treated distillery effluent with common duckweed (Lemna minor)

Duckweed (Lemna minor) a small vascular plant, grows rapidly, is sensitive to a wide variety of toxicants and is easy to culture. A method is described that measures duckweed frond growth, chlorophyll, protein and biomass content as indicator of growth inhibition. The physico-chemical analysis of anaerobically treated distillery effluent revealed high BOD (28,000 mg/l), COD (52,400 mg/l) and dark brown colour (180,000 Co. Pt.). This effluent showed high toxicity to Lemna minor after 96 h of exposure in laboratory condition. EC50 of the fronds for chlorophyll, protein and biomass was found to be 25%, however, the bacterial decolourised effluent showed reduction of BOD (87.50%), COD (84.50%) and colour (76%). Further the toxicity evaluation with Lemna minor showed toxicity reduction up to 63% for all tested parameters. The EC50 noted for chlorophyll, protein and biomass was 100% concentration of decolourised effluent.     

Display rate by male fairy-wrens (Malurus cyaneus) during the fertile period of females has little influence on extra-pair mate choice

Empirical and theoretical studies have only recently begun to examine how females use complex multi-component displays when selecting mates. Superb fairy-wrens are well suited to the study of female choice because females have control over extra-group paternity and cuckold their mates at high rates, while males possess a variety of sexually selected traits. Available evidence suggests that females base their extra-group mate choice on the timing of male moult into breeding plumage or the onset of display. However, males continue to perform elaborate displays throughout the season, and direct most displays to females during their fertile period. We therefore conducted focal observations on fertile females to quantify the frequency of male display and used microsatellite genotyping to compare the role of display rate during the breeding season and the timing of male moult on female mate choice. We show that the addition of data on male display rate does not improve our ability to predict which males obtain extra-group paternity. The timing of male moult into breeding plumage remains the only predictor of male extra-group reproductive success. Nevertheless, we found that males displayed more to females that were unable to select extra-group mates on the basis of the timing of moult or the onset of display. This raises the possibility that there are circumstances when females use display rate to discriminate between potential extra-group sires. Overall this study supports the theoretical prediction that females are more likely to base their mate choice on reliable indicators of male quality such as fixed morphological traits and displays of endurance, in this case an early moult into breeding plumage and the performance of an elaborate display during the winter, than a flexible behavioural trait such as display rate during the breeding season. Received: 26 January 2000 / Revised: 1 August 2000 / Accepted: 26 August 2000     

Effects of Cr(III) organic compounds on Lactobacillus plantarum

Biotransformation of Cr(VI) to less toxic Cr(III) has been known to produce insoluble Cr(III) compounds and soluble Cr(III) organic complexes. However, recent research reports have indicated that Cr(III) organic complexes are relatively stable in the environment. Little has been reported on the fate and toxic effects of Cr(III) organic compounds on organisms. In this study, the toxic effects of the soluble Cr(III) organic complexes [Cr(III) citrate, Cr(III) histidine, Cr(III) lactate and Cr(III) glutamate] to a local strain of Lactobacillus plantarum isolated from sauerkraut was investigated. Growth inhibition, viable cell count and lactic acid inhibition were measured to determine the toxicity potential of the test compounds. The EC₅₀ values of Cr(III) citrate, Cr(III) histidine, Cr(III) lactate, and Cr(III) glutamate, calculated from the percent growth inhibition were found to be 56 mg L^?1, 70 mg L^?1, 81 mg L^?1, and 85 mg L^?1, respectively. Similar trend was observed in the viable cell counts and lactic acid production. Cr(VI) was observed to be more toxic than the Cr(III) organic compounds, while inorganic Cr(III) was the least toxic. The severity seemed to increase with increase in chromium compounds’ concentration. The results showed that Cr(III) citrate was the most toxic Cr(III) organic compound, while Cr(III) glutamate was the least.     

转野生荠菜凝集素基因棉花对赤子爱胜蚓的影响

在实验室条件下分别给赤子爱胜蚓(Eisenia foetida)饲喂在自然状况下可能接受的棉叶最高添加量和2倍最高添加量的转野生荠菜凝集素(WSA)基因棉花(Gossypium hirsutum)叶片,并以其亲本棉花叶片为对照,以牛粪为阴性对照,以农药为阳性对照,研究种植转WSA基因棉花对赤子爱胜蚓死亡率、生长及繁殖的影响。结果表明,在49 d的试验周期内,与取食亲本棉花叶片的赤子爱胜蚓相比,取食转WSA基因棉花叶片的赤子爱胜蚓的死亡率,体质量,GST、SOD、纤维素酶活性以及蚓茧数和小蚯蚓数均无显著差异,未发现转WSA基因棉花对赤子爱胜蚓有不利影响。     

Effects of petroleum products on bull kelp (Nereocystis luetkeana)

Although research has been conducted on the effects of oil on the giant kelp Macrocystis pyrifera, no similar studies have been completed on bull kelp, Nereocystis leutkeana, the dominant kelp in Washington State, British Columbia, and Alaska. The effects of three petroleum products [diesel fuel, intermediate fuel oil (IFO), and crude oil] were tested before and after weathering on N. luetkeana. Whole plants were exposed to petroleum product for 4 or 24 h and then transferred to the field; observations on the condition of the plants were made daily for 7 d. In addition, controlled bioassays were performed to measure the effects of petroleum exposure on net photosynthetic rate (NP) and respiration rate (R), using light-and dark-bottle techniques. These experiments verified the susceptibility of N. luetkeana tissue to the damaging effects of direct exposure to several oil types. The 4 h exposures to weathered diesel and unweathered IFO, and 24 h exposures to unweathered and weathered diesel and IFO resulted in moderate to severe damage to kelp tissue (i.e., clearly delineated bleached line accompanied by tissue necrosis). Weathered diesel was more toxic than unweathered diesel. The most severe damage to bull kelp was concentrated at the meristematic zone (junction of stipe and bulb) where new tissue growth occurs. Petroleum type significantly affected stipe and blade NP, R, and NP:R ratios. Diesel treatments had a greater negative effect on NP than did the IFO treatments. Based on these experiments, the relative ranking of the damaging effects of petroleum treatment on bull kelp are weathered diesel>unweathered IFO>unweathered diesel>weathered IFO>unweathered crude>weathered crude.     

Performance of duckweed (Lemna minor L.) on different types of wastewater treatment

Duckweed (Lemna minor L.) has a wide application in Turkey having suitable climatic conditions. In this study, the growth of duckweed was assessed in laboratory scale experiments. They were fed with municipal and industrial wastewater at constant temprature. COD, total nitrogen (TN), total phosphorus (TP) and ortho-phosphate (OP) removal efficiencies of the reactors were monitored by sampling influent and effluent of the system. Removal efficiency in this study reflects optimal results: 73-84% COD removal, 83-87% TN removal, 70-85% TP removal and 83-95% OP removal. The results show that the duckweed-based wastewater treatment is capable of treating the laboratory wastewater.