Learned or innate production of acoustic signals in fishes: a test using a cyprinid

No information on the inheritance of the ability to produce sounds exists for fishes. In birds, which usually provide extensive post-hatching parental care, acoustic signals are learned in some species but are innate in others. Almost no fishes provide extensive post-hatching parental care and, consequently, the offspring have little opportunity to hear and learn sounds produced by the parents (usually the male in fishes); they may, however, be exposed to acoustic signals of conspecifics in the same habitat. We used a cyprinid, Codoma ornata, to test whether sound production is learned from the parents or whether it is innate. Fertilized eggs of this species were raised in isolation from adults. Upon maturity, these fish were tested for sound production in aggressive and reproductive contexts. Fish which had no contact with adults, and therefore no opportunity to hear the acoustic signals of their species, produced sounds that were similar to those produced by their parents, and they produced these in the same contexts. Significant differences were observed in dominant frequency for one context, with the smaller F₁ fish having signals of higher frequency than parental fish. Since no opportunity for learning existed, this provided evidence that the ability to produce sounds is innate in this minnow species.     

Sound Production in Codoma ornata (Girard) (Cyprinidae)

Male Codoma ornata produce sounds associated with aggression and spawning activities during the breeding season. Females do not produce sounds. Males most often produced sounds associated with escalated displays of aggression, courtship and the spawning act. C. ornata spawn in crevices, but previously were reported to spawn as egg-clusterers in cavities. Structurally, sounds are low frequency, vary in duration according to context and are not harmonic. The mechanism of sound production is unknown.     

Behaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)

Background

Sound production is widespread among fishes and accompanies many social interactions. The literature reports twenty-nine cichlid species known to produce sounds during aggressive and courtship displays, but the precise range in behavioural contexts is unclear. This study aims to describe the various Oreochromis niloticus behaviours that are associated with sound production in order to delimit the role of sound during different activities, including agonistic behaviours, pit activities, and reproduction and parental care by males and females of the species.

Methodology/Principal Findings

Sounds mostly occur during the day. The sounds recorded during this study accompany previously known behaviours, and no particular behaviour is systematically associated with sound production. Males and females make sounds during territorial defence but not during courtship and mating. Sounds support visual behaviours but are not used alone. During agonistic interactions, a calling Oreochromis niloticus does not bite after producing sounds, and more sounds are produced in defence of territory than for dominating individuals. Females produce sounds to defend eggs but not larvae.

Conclusion/Significance

Sounds are produced to reinforce visual behaviours. Moreover, comparisons with O. mossambicus indicate two sister species can differ in their use of sound, their acoustic characteristics, and the function of sound production. These findings support the role of sounds in differentiating species and promoting speciation. They also make clear that the association of sounds with specific life-cycle roles cannot be generalized to the entire taxa.     

Costs of egg ventilation for male common gobies breeding in conditions of low dissolved oxygen

This study examines the effects of harsh environmental conditions on life history trade-offs in parental care in a marine fish, the common goby, Pomatoschistus microps. We compared male parental care and hatching success over two sequential brood cycles in fish breeding in conditions of either low dissolved oxygen or normal levels of oxygen. Males compensated for a low oxygen environment by increasing the time they spent fanning water over their eggs, as well as their fanning tempo. They also increased the frequency of egg-directed activities and decreased nest-building activities. Males in the low oxygen treatment lost more weight than control fish during the first spawning, and were more likely to abandon care during the second spawning. Males that completed care under low oxygen conditions did not differ from control males in the hatching success of their offspring or the size of young at hatching, but hatching started on average 1 day later. Thus, greater parental allocations to offspring while breeding in a harsh environment led to reduced future allocations. Copyright 1999 The Association for the Study of Animal Behaviour.     

Plasma thyroid hormones and hepatic nucleic acids in relation to sex of tilapia Oreochromis niloticus

Tilapia has a sex-related differential growth between males and females. This trial was conducted in order to test the relationships between growth, plasma thyroid hormones and hepatic nucleic acids levels of two tilapia Oreochromis niloticus groups: one all male group that was treated with 17α-methyltestosterone and a untreated group with males and females. Tilapia (average weight 9.7 g) were raised at a stocking of 30 fish per tank and fed a 35% protein diet for 215 days. The mean body weight of the all male group was significantly higher than that of the control group (P < 0.01). No significant differences were observed in plasma thyroxine (T4) and triiodothyronine (T3) levels, hepatic ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) levels between the two groups during the entire trial period. After 5 months females showed plasma T3 levels and a RNA/protein ratio higher than males of the two groups, and the differences were significant in the final phase of the experiment (P < 0.05). These results suggest that the observed differences were linked to the greater development of female gonads in tilapia.     

Vocalization during Agonistic Behaviour in Cottus gobio L. (Cottidae): An Acoustic Threat Display

Agonistic behaviour in the river bullhead C. gobio consists of visual (raising gill covers and fins, lowering the head, darkening) and acoustic (single knock sounds and trains of knock sounds) threat displays, rarely followed by attacks and bites. This study investigates the relationship of vocalizations with size, dominance, territory dimensions and sex of the opponents. Four groups, each consisting of a big male, a small male and a female, were each investigated for three different days. The number of won contests of each individual, the numbers of each sound produced during these encounters and the tank part where encounters took place were determined. Subordinate fish emit fewer sounds but relatively far more trains of knock sounds than dominant ones. They produce relatively more sounds under shelters whereas dominants do this on uncovered areas. α-fish produce more calls during agonistic encounters with β-fish than Ω fish. In β-individuals no such difference was noted. Basically no sex related behaviour could be observed. In each area of the tank one individual won most contests (= territory). Dimensions of territories differed significantly between individuals in each tank (α-, β-, Ω-fish). In no case were all three individuals able to maintain territories. Relative sizes of fish correlate significantly with relative numbers of successful encounters and with territory dimensions. Furthermore, both parameters are positively correlated with the numbers of sounds emitted by an individual. Sound production in C. gobio functions as an acoustical threat display. Because of the high energy costs of sound emission underwater it might be a very effective method of assessing the fighting ability of an opponent.     

Distribution and reproduction of the Patagonian toothfish Dissostichus eleginoides Smitt around the Falkland Islands

Population characteristics of the Patagonian toothfish Dissostichus eleginoides were investigated based on material collected from both trawl and longline fisheries in Falkland Islands' waters. The fish occurred between 56 and 2122 m and attained 225 cm total length ( L _T). Males matured earlier, L _T at 50% maturity was 86 cm for males v . 90 cm for females. Subadult fish foraged at depths of <600 m, whereas adult Patagonian toothfish lived at >600 m. Spawning occurred on slopes of the Burdwood Bank at c . 1000 m depth with a minor peak in May, and a major peak in July to August. Males arrived at the spawning grounds first. Between spawning peaks both sexes remained around the Burdwood Bank with males occurring at greater depths than females. The Patagonian toothfish in south‐east Patagonia and the Falkland Islands had a long juvenile and sub‐adult period in the relatively shallow and warm waters of the outer shelf and upper slope unlike that of juveniles in other Patagonian toothfish populations. The migratory life style of the south‐west Atlantic population is probably very different from that of other populations, which tend to be resident as they are inclined to inhabit the waters around oceanic islands and sea mounts with narrow shelf areas.     

The food of the Nile perch, Lates niloticus (L.), after the disappearance of the haplochromine cichlids in the Nyanza Gulf of Lake Victoria (Kenya)

After the disappearance of the haplochromine species in the Nyanza Gulf of Lake Victoria as a result of predation by Lates niloticus , the latter has turned its attention to aquatic invertebrates and other fish. Changes in the diet of the Nile perch with increase in its size have been observed: young L. niloticus preyed mostly on invertebrates, including crustaceans and various small aquatic insects; large, immature L. niloticus supplemented the invertebrate diet with both young and small fish; adults above 80 cm total length were mainly piscivorous. L. niloticus feeds on fish prey of about one third its own length.
The tendency of L. niloticus to switch from one prey item to another, depending on availability, is reported; e.g., in the Nyanza Gulf, the prey diet has shifted from the haplochromine to Caridina nilotica and L. niloticus juveniles.     

Experimental analysis of some factors affecting parental expenditure and investment inGasterosteus aculeatus (Gasterosteidae)

Synopsis Parental investment is the cost of providing parental care. Parental investment was measured in the paternal stickleback,Gasterosteus aculeatus, by comparing future survival (measured indirectly as energy content of the body) and growth of parental and non-parental males. The time taken by parental males to renest was also measured. Male energy content was unaffected after a single parental cycle and no difference in growth rate was detected. Re-nesting was delayed. The effect of stressing parental males by exposing them to potential predators of their offspring and reducing their ration level, was also investigated. Stressed males had reduced energy contents in comparison with unstressed parental males. The time taken by stressed males to re-nest was unaffected. Males on low rations did not fan significantly less than well-fed males. Males exposed to brood predators did fan significantly less than parental males not exposed to brood predators, but the former did spend nearly 60% of their time attacking the predators when present.     

The African cichlid fish Astatotilapia burtoni uses acoustic communication for reproduction: sound production, hearing, and behavioral significance

Sexual reproduction in all animals depends on effective communication between signalers and receivers. Many fish species, especially the African cichlids, are well known for their bright coloration and the importance of visual signaling during courtship and mate choice, but little is known about what role acoustic communication plays during mating and how it contributes to sexual selection in this phenotypically diverse group of vertebrates. Here we examined acoustic communication during reproduction in the social cichlid fish, Astatotilapia burtoni. We characterized the sounds and associated behaviors produced by dominant males during courtship, tested for differences in hearing ability associated with female reproductive state and male social status, and then tested the hypothesis that female mate preference is influenced by male sound production. We show that dominant males produce intentional courtship sounds in close proximity to females, and that sounds are spectrally similar to their hearing abilities. Females were 2-5-fold more sensitive to low frequency sounds in the spectral range of male courtship sounds when they were sexually-receptive compared to during the mouthbrooding parental phase. Hearing thresholds were also negatively correlated with circulating sex-steroid levels in females but positively correlated in males, suggesting a potential role for steroids in reproductive-state auditory plasticity. Behavioral experiments showed that receptive females preferred to affiliate with males that were associated with playback of courtship sounds compared to noise controls, indicating that acoustic information is likely important for female mate choice. These data show for the first time in a Tanganyikan cichlid that acoustic communication is important during reproduction as part of a multimodal signaling repertoire, and that perception of auditory information changes depending on the animal's internal physiological state. Our results highlight the importance of examining non-visual sensory modalities as potential substrates for sexual selection contributing to the incredible phenotypic diversity of African cichlid fishes.     

Sound production in the cichlid Tilapia mossambica Peters

Aquarium-bred adult and juvenile Tilapia mossambica Peters can produce sounds ofvarying frequency, duration and intensity. However, minor environmental disturbancesmay cause the fish to fall silent for long periods. The sounds produced by excited feedingfishes are different from those produced by territorial males and from those emitted by fryswimming in school formation. The frequency of the sounds recorded varied from about1–16 kHz; no data are available on frequencies lower than 1 kHz. The sound producingmechanism consists of a single ventral and two dorsal pharyngeals located in the buccalcavity and provided with numerous small teeth. These teeth have a specially modifieddistal surface area which is already evident in younger fish. Young Tilapia , including3-week old fry, are able to emit sounds as soon as a sufficient number of teeth havedeveloped in the pharyngeal region.     

Fishing near sea-cage farms along the coast of the Turkish Aegean Sea

This study reports on the yield of commercially important species captured intentionally around and under fish-cage farms using specific types of gear from both sea-cage farmers and artisanal fishermen, and to identify the species composition of these catches. The 2004–2008 research was carried out in 21 fish farms, randomly chosen along the coast of Izmir Province on the Aegean Sea. A total of 91 persons were interviewed, including directors, fishers from the fish farms and artisanal fishermen. The technical characteristics of a special trap used by some fish farmers were diagramed. Total wild fish catch quantities as well the species raised in the sea-cages were recorded. A total of 34 finfish and four invertebrate species were identified from the sea-cage farm fishery. Eight fish species according to the descending quantities raised were bogue ( Boops boops ), grey mullet ( Mugil spp.), blackspot seabream ( Pagellus bogaraveo ), salema ( Sarpa salpa ), common two-banded seabream ( Diplodus vulgaris ), annular seabream ( Diplodus annularis ), striped seabream ( Lithognathus mormyrus ) and gilthead seabream ( Sparus aurata ). Mean quantities of wild fish caught from 2004 to 2008 in a sampled farm were 13 998 ± 210, 34 434 ± 482, 30 116 ± 529, 27 893 ± 429, and 32 366 ± 808 kg, respectively. There were significant differences between fish amounts and years (P   < 0.05).     

Ecology and sound signaling of relict katydid Deracantha onos (Pallas, 1772) (Orthoptera, Tettigoniidae, Bradyporinae)

Life history and acoustic signaling of a Central Asian species Deracantha onos (Pall.) are described. Males and females produce calling signals and protest sounds. For the first time, electronograms of stridulatory files, oscillograms, and frequency spectra of some acoustic signals are given.     

Male field crickets that provide reproductive benefits to females incur higher costs

Abstract.  1. Females often select mates based on signals correlated with the quality of the direct benefits that males will provide to them. A male's quality as a mate and the structure of his mating signals may covary because both traits are energetically expensive for males to produce and because both traits are affected by short-term changes in nutritional condition.
2. In the variable field cricket, Gryllus lineaticeps , previous work has shown that females receive reproductive benefits from males that produce higher chirp rates and lifespan benefits from males that produce longer chirp durations, even when they only receive the sperm and seminal fluid contained in male spermatophores. Higher chirp rates are energetically expensive for males to produce, and chirp rate is strongly affected by diet quality, whereas longer chirp durations do not appear to be expensive for males to produce, and chirp duration does not appear to be affected by male diet quality. In this study two hypotheses were tested about the energetic costs of spermatophore production: (1) that spermatophores are expensive for males to produce and (2) that males providing greater direct benefits to females incur higher costs of spermatophore production.
3. Males that were provided with a lower quality diet took longer to produce a new spermatophore. This result suggests that spermatophores are costly for males to produce.
4. Males that produced higher chirp rates took longer to produce a new spermatophore. This result suggests that male chirp rate and female reproductive benefits may covary because both traits are energetically expensive for males to produce and thus are affected by male nutritional condition. There was no association, however, between male chirp duration and spermatophore production time.     

Phylogeny and historical demography of economically important rodents of the genus Arvicanthis (Mammalia: Muridae) from the Nile Valley: of mice and men

The present study clarified the taxonomy, phylogeny and historical demography of semicommensal Nile rats ( Arvicanthis ) from the Nile Valley in Sudan. Nile rats are important crop pests and zoonotic disease reservoirs and are closely associated with agricultural settlements in the Nile Valley. Phylogenetic analysis of the complete cytochrome b gene (1140 bp) of 23 individuals from six localities in Sudan (from two previously recognized species, Arvicanthis niloticus and Arvicanthis testicularis ), supported the existence of only a single species, A. niloticus , from the Nile Valley. Historical demography of the Sudanese Nile Valley population inferred from mismatch coefficients indicated that an exponential population expansion event occurred approximately 144 000–288 000 years ago, corresponding in time with early human expansion and colonization from Africa to the Middle East, Europe, and the world. The inferred high level of gene flow and large size of Sudanese Nile populations of A. niloticus is consistent with historically recent (300 years ago) exponential human population growth and intense agricultural activity inferred from archaeological and historical evidence. Two African Arvicanthis clades were well supported by the broader phylogenetic analysis: (1) A. niloticus , Arvicanthis abyssinicus and Arvicanthis neumanni and (2) Arvicanthis rufinus and Arvicanthis ansorgei from western Africa. Within the first clade, divergence between lineages of A. niloticus s.s. from west and north-east Africa (8.9%) suggests specific recognition, but sampling of geographically intermediate localities is required. Based on hypothesized palaeodrainage and palaeoclimatic patterns, we propose a simple model for speciation of Arvicanthis in Africa.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 641–655.     

Zur Funktion von Warnfarben: Die Reaktion junger Stare auf wespenähnlich schwarz-gelbe Attrappen

Social regulation of developmental rate of the African cichlid fish, Haplochromis bur-toni, was studied experimentally. Broods were raised under three different social conditions: total isolation, with no visual, physical or chemical contact with siblings; physical isolation, with no physical or chemical contact with siblings; and in social groups. Development of behavior and color patterns were observed in fish from 2 to 14 weeks of age. Males were sacrificed at 4-week intervals to measure growth and maturation state. Results showed that developmental rate is influenced by the social environment. Males with no territories (raised in groups) grew and matured more slowly than those in all other conditions. These males were not prevented from maturing but both the rate and phenotypic expression of maturation were inhibited.     

Sex-Specific Differences in Agonistic Behaviour,Sound Production and Auditory Sensitivity in the Callichthyid Armoured Catfish Megalechis thoracata

Background

Data on sex-specific differences in sound production, acoustic behaviour and hearing abilities in fishes are rare. Representatives of numerous catfish families are known to produce sounds in agonistic contexts (intraspecific aggression and interspecific disturbance situations) using their pectoral fins. The present study investigates differences in agonistic behaviour, sound production and hearing abilities in males and females of a callichthyid catfish.

Methodology/Principal Findings

Eight males and nine females of the armoured catfish Megalechis thoracata were investigated. Agonistic behaviour displayed during male-male and female-female dyadic contests and sounds emitted were recorded, sound characteristics analysed and hearing thresholds measured using the auditory evoked potential (AEP) recording technique. Male pectoral spines were on average 1.7-fold longer than those of same-sized females. Visual and acoustic threat displays differed between sexes. Males produced low-frequency harmonic barks at longer distances and thumps at close distances, whereas females emitted broad-band pulsed crackles when close to each other. Female aggressive sounds were significantly shorter than those of males (167 ms versus 219 to 240 ms) and of higher dominant frequency (562 Hz versus 132 to 403 Hz). Sound duration and sound level were positively correlated with body and pectoral spine length, but dominant frequency was inversely correlated only to spine length. Both sexes showed a similar U-shaped hearing curve with lowest thresholds between 0.2 and 1 kHz and a drop in sensitivity above 1 kHz. The main energies of sounds were located at the most sensitive frequencies.

Conclusions/Significance

Current data demonstrate that both male and female M. thoracata produce aggressive sounds, but the behavioural contexts and sound characteristics differ between sexes. Sexes do not differ in hearing, but it remains to be clarified if this is a general pattern among fish. This is the first study to describe sex-specific differences in agonistic behaviour in fishes.     

Physiological responses in Nile tilapia exposed to different photoperiod regimes

After conditioning Nile tilapia Oreochromis niloticus for 2 weeks, the photoperiod regime of 12 tanks of fish was changed to a 6L : 6D photoperiod while 12 further tanks were retained on the conditioning photoperiod regime (12L : 12D). Blood samples were collected 3 days (first sampling) and 3 months (second sampling) after changing the photoperiod regime. Blood was collected at 6 h intervals from both photoperiod regimes (1000, 1600, 2200 and 0400 hours). At the first sampling time, fish in the 6L : 6D had significantly higher cortisol both in the light and dark phases than levels in fish in the 12L : 12D photoperiod. At the second sampling time, the levels were significantly higher only in the light phase. The levels of cortisol, glucose and Cl⁻ in fish exposed to the 6L : 6D photoperiod, however, were far lower than those of acute stress‐induced levels observed in fish exposed to a stress experiment. Furthermore, there were no significant differences in overall values of all the variables between the photoperiod regimes at the second sampling time. This indicated that the fish exposed to the 6L : 6D photoperiod were not chronically stressed. Significantly higher blood lymphocyte counts were observed in fish exposed to the 6L : 6D compared to those of the 12L : 12D photoperiod during the light phase at the second sampling time. Other variables (glucose, Cl⁻, haematocrit and neutrophil) did not show a significant difference between the treatments at either sampling time. These results demonstrated that the artificial photoperiod regime did not cause a significant acute or chronic stress response in Nile tilapia.     

Adjusting parental investment to changing environmental conditions: the effect of food ration on parental behaviour of the convict cichlid, Cichlasoma nigrofasciatum

Animals that care for their offspring may vary the amount of care provided for a particular brood in relation to environmental conditions. Food availablity is one factor that may affect the costs and benefits associated with parental investment. The convict cichlid, Cichlasoma nigrofasciatum, is a small, substrate-spawning cichlid from Central America. Both male and female provide parental care for eggs and fry. Paris were kept at one of three ration levels, high, medium or low. Time spent in parental fanning by females was positively related to ration. Males spent less time fanning than females and their parental behaviour varied considerably between individuals. Males on the high ration spent slightly more time fanning than those on the lower rations. The number of eggs produced per spawning and the post-spawning weight of both males and females were significantly and positively related to ration. Foraging frequency of both males and females was inversely related to ration. There was no significant effect of ration on the frequency of mouthing eggs and young or on intra-pair aggression. Eggs of low-ration fish hatched earlier than those of medium- and high-ration fish but there was no significant difference in the number of days that the young survived. These results suggest that the allocation of time and effort between parental and maintenance activities differs in relation to food supply. Parents may provide more care for the large brood produced when food is plentiful but place more emphasis on their own survival when food is short and broods are small.     

Function of Sound Production by the Skunk Loach Botia horae (Pisces,Cobitidae)

In agonistic interactions with conspecifics, skunk loaches (Botia horae) typically exhibit lateral displays, attacks, and produce a sound (a “click”). Four experiments were conducted to determine the functional significance of the click sound. Behaviors of resident fish were monitored while characteristics of their shelter and the size or type of intruder fish introduced were varied. Manipulations in the four experiments involved: 1) the configuration of the available shelter; 2) the size or recent history of intruder fish; 3) playbacks of “click” sounds or aquarium noise; or 4) muting of resident fish. Lateral displays, attacks, and sounds produced by residents were monitored, and the responses of residents were analyzed in terms of the functional significance of “click” sounds to juvenile skunk loaches.