Haplochromis Piceatus Research Articles

Parasite diversity of introduced fish Lates niloticus, Oreochromis niloticus and endemic Haplochromis spp. of Lake Victoria, Kenya.

This study reports on the status of metazoan fish parasites in Lake Victoria following the establishment of introduced Lates niloticus (Latidae) and Oreochromis niloticus (Cichlidae) and changes in environmental quality. For this study, 412 fish specimens were examined for parasites: 103 L. niloticus, 165 O. niloticus, 82 Haplochromis piceatus and 62 H. humilior (endemic cichlids). In total, 25 parasite taxa were identified: Lates niloticus (6), O. niloticus (19) and Haplochromis spp. (13). The myxosporean Henneguya ghaffari, prevalence (P) = 79% and the monogenean Diplectanum lacustris (P = 34%), were the dominant parasites on L. niloticus. Myxobolus sp. (P = 44%) was dominant on O. niloticus while for the haplochromines, metacercariae of 'Neascus' sp. (Diplostomidae) was dominant (P = 37%). Contrary to reports of high diversity of monogeneans on endemic species, the haplochromines harboured only Cichlidogyrus gillardinae (P = 6.9%). Oreochromis niloticus harboured seven monogenean species: Cichlidogyrus sclerosus, C. halli, C. tilapiae, C. quaestio, Scutogyrus longicornis, Gyrodactylus cichlidarum and G. malalai-they appear to have been co-introduced with the fish. Cichlidogyrus gillardinae, C. quaestio, G. malalai and the acanthocephalan Acanthogyrus (Acathosentis) tilapiae are recorded for the first time in Lake Victoria, representing new geographical records. Presence of A. (A) tilapiae in Haplochromis spp. indicates possible spillover from O. niloticus. Low prevalence and diversity of monogeneans, crustaceans and glochidia on the fish corresponded with increased pollution in the lake. Overall, changing environmental conditions and introductions of fish species have contributed to parasite community changes in Lake Victoria.

Hypoxia-induced changes in hemoglobins of Lake Victoria cichlids.

In a previous study, broods of the Lake Victoria cichlid Haplochromis ishmaeli raised under hypoxic or normoxic conditions showed striking differences in isohemoglobin (isoHb) pattern that were not observed in two other cichlids that do not belong to the Lake Victoria species flock. We therefore hypothesized that the adaptive mechanism seen in H. ishmaeli in response to hypoxia constitutes a trait that the Lake Victoria species flock inherited from ancestors that lived in hypoxic environments. We tested this hypothesis by designing split-brood experiments with three other representative species from the same species flock: the insectivorous Haplochromis thereuterion, the mollusk-shelling Platytaeniodus degeni and the zooplanktivorous Haplochromis piceatus, while keeping H. ishmaeli as a reference. Split broods were raised, under either normoxia or hypoxia. All hypoxia-raised (HR) individuals of each of the four species exhibited a distinctly different isoHb pattern compared with their normoxia-raised (NR) siblings. The hemoglobin of HR H. thereuterion showed higher O2 affinity compared with NR siblings particularly in the presence of ATP and GTP, indicating that blood of HR juveniles has significantly improved O2-binding affinity under hypoxic conditions. We also tested the capacity to acclimate at greater age in two species by reversing the O2 condition after 7 (H. thereuterion) and 4 (H. ishmaeli) months. After reacclimation for 1 and 2 months, respectively, we found incomplete reversal with intermediate isoHb patterns. As three of the four species do not encounter hypoxic conditions in their environment, this unique trait seems to be a relic inherited from predecessors that lived in hypoxic environments.

Behavioural responses to sound exposure in captivity by two fish species with different hearing ability

Underwater sound generated by human activities is increasing in, on and near aquatic environments. Such anthropogenic noise can induce artificially elevated ambient sound levels and cause various detrimental effects in fish, such as temporary or permanent hearing loss, masking of relevant acoustic signals and cues or behavioural changes that may have fitness consequences. Also, captive fish are often exposed to noisy conditions, which may have consequences for production in aquaculture, biases in scientific results in laboratories or welfare in hobby aquaria. However, we still have limited insight into how fish cope with artificial sound exposure and how species differ in sensitivity. Here, we compared zebrafish, Danio rerio, and Lake Victoria cichlids, Haplochromis piceatus, the former being sensitive to lower absolute thresholds and wider spectral ranges than the latter. Experimental sound exposure induced a significant reduction in swimming speed in the first minute of exposure for both species in captive conditions. Furthermore, zebrafish showed clear startle response behaviour with the onset of the sound exposure leading to an initial, brief increase in swimming speed, which was not found for the cichlids. Neither species showed spatial shifts away from the active speaker in the horizontal plane, but cichlids shifted downwards to spend more time in the bottom area of the fish tank after the onset of sound exposure, while zebrafish retained their average swimming height during the same exposure levels. Our results show that sound exposure can cause both similar and species-specific responses in two fish species and that these responses are not obviously related to differences in their hearing ability.

The sonic hedgehog signaling pathway and the development of pharyngeal arch Derivatives in Haplochromis piceatus, a Lake Victoria cichlid

ObjectivesPharyngeal arches develop in the head and neck regions, and give rise to teeth, oral jaws, the hyoid bone, operculum, gills, and pharyngeal jaws in teleosts. In this study, the expression patterns of genes in the sonic hedgehog (shh), wnt, ectodysplasin A (eda), and bone morphogenetic protein (bmp) pathways were investigated in the pharyngeal arches of Haplochromis piceatus, one of the Lake Victoria cichlids. Furthermore, the role of the shh pathway in pharyngeal arch development in H. piceatus larvae was investigated. MethodsThe expression patterns of lymphocyte enhancer binding factor 1 (lef1), ectodysplasin A receptor (edar), shh, patched 1 (ptch1), bmp4, sp5 transcription factor (sp5), sclerostin domain containing 1a (sostdc1a), and dickkopf 1 (dkk1) were investigated in H. piceatus larvae by in situ hybridization. The role of the shh pathway was investigated through morphological phenotypic characterization after its inhibition. ResultsWe found that lef1, edar, shh, ptch1, bmp4, dkk1, sostdc1a, and sp5 were expressed not only in the teeth, but also in the operculum and gill filaments of H piceatus larvae. After blocking the shh pathway using cyclopamine, we observed ectopic shh expression and the disappearance of ptch1 expression. After six weeks of cyclopamine treatment, an absence of teeth in the oral upper jaws and a poor outgrowth of premaxilla, operculum, and gill filaments in juvenile H. piceatus were observed. ConclusionsThese results suggest that the shh pathway is important for the development of pharyngeal arch derivatives such as teeth, premaxilla, operculum, and gill filaments in H. piceatus.

Husbandry of a Lake Victoria cichlid, the Pitch‐black fulu Haplochromis piceatus, in public aquariums: a 20 year retrospective

The Lake Victoria haplochromine cichlids comprise a unique ‘species flock’ of over 500 historic species, of which perhaps only half still exist because of the introduction of invasive species and eutrophication of the Lake. Dr Les Kaufman supervised the establishment of captive populations of those cichlids he was able to acquire from Africa and Europe by developing the first North American regional studbook. Long‐term propagation of these fish was then undertaken by public aquariums in Europe and North America. One species, the Pitch‐black fulu Haplochromis piceatus, stands out as it has thrived at public aquariums and within the organizational structure of the Association of Zoos and Aquariums Species Survival Plans. These cooperative breeding programmes focus on the conservation of select species of threatened animals. Captive populations of H. piceatus at public aquariums in the United States show a relatively slow loss of genetic diversity. Additionally, fish in at least two breeding programmes show a higher than expected heterozygosity, indicating that these programmes are successfully keeping their fish from inbreeding. The husbandry and genetic management of this population of fish is outlined, hopefully providing useful information for nascent breeding programmes of other aquatic species at zoos and aquariums around the world.

Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits.

BackgroundAs in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species.Methodology/Principal FindingsBecause cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a “suction feeder” (Haplochromis piceatus) and a “biter” (H. fischeri). The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs.Conclusions/SignificanceOur findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two studied haplochromine cichlids, stressing the importance of including species-specific information at the gender level when addressing interspecific functional/morphological differences.

Polymorphism in developmental timing: intraspecific heterochrony in a Lake Victoria cichlid

Biologists measure developmental time by dividing development into arbitrary time blocks called "stages." This is a reasonable approach, provided that developmental timing is precisely controlled within a species. However, the degree of this precision is unknown. This is unfortunate because precision in developmental timing at the population level is a central issue to the whole research program of heterochrony. To examine this issue, we apply Ontogenetic Sequence Analysis to 261 embryos of the Lake Victoria cichlid Haplochromis piceatus. The result of our analysis can be mapped as a complex web of 26,880 equally parsimonious developmental sequences. This topology reflects timing polymorphism (intraspecific heterochrony) among embryos of this species. Because of this timing polymorphism, it is not possible to define discrete "stages" in this cichlid (although there is sufficient sequence signal to assess the maturity of embryos). More generally, we show that sequence polymorphism creates uncertainty about how a given embryo will develop implying that the mechanisms controlling developmental timing in embryos lack precision. For this reason, it is imperative to consider patterns of embryonic variability when measuring developmental time.

Developmental stages until hatching of the Lake Victoria cichlid Haplochromis piceatus (Teleostei: Cichlidae)

Because little is known about embryonic developmental stages in any haplochromine cichlid, we describe here a series of normal stages of the Lake Victoria cichlid Haplochromis piceatus. We collected 273 embryos and scored them for 47 morphological characters. The result was an illustrated series of 12 stages from embryonic shield until hatching based on live, fixed, and histological material. We defined each stage according to a single "key" character that applied to all embryos of that stage. Other characters forming part of the stage descriptions were not necessarily present in all embryos of a stage. We compare our findings with published studies of other freshwater teleosts and find wide variation in staging systems. Our data will form a baseline for further research on cichlid development.

Transcriptome analysis of the response to chronic constant hypoxia in zebrafish hearts

Insufficient blood supply during acute infarction and chronic ischemia leads to tissue hypoxia which can significantly alter gene expression patterns in the heart. In contrast to most mammals, some teleost fishes are able to adapt to extremely low oxygen levels. We describe here that chronic constant hypoxia (CCH) leads to a smaller ventricular outflow tract, reduced lacunae within the central ventricular cavity and around the trabeculae and an increase in the number of cardiac myocyte nuclei per area in the hearts of two teleost species, zebrafish (Danio rerio) and cichlids (Haplochromis piceatus). In order to identify the molecular basis for the adaptations to CCH, we profiled the gene expression changes in the hearts of adult zebrafish. We have analyzed over 15,000 different transcripts and found 376 differentially regulated genes, of which 260 genes showed increased and 116 genes decreased expression levels. Two notch receptors (notch-2 and notch-3) as well as regulatory genes linked to cell proliferation were transcriptionally upregulated in hypoxic hearts. We observed a simultaneous increase in expression of IGF-2 and IGFbp1 and upregulation of several genes important for the protection against reactive oxygen species (ROS). We have identified here many novel genes involved in the response to CCH in the heart, which may have potential clinical implications in the future.Electronic supplementary materialThe online version of this article (doi:10.1007/s00360-007-0201-4) contains supplementary material, which is available to authorized users.

Interactions between the pharyngeal jaw apparatus, feeding behaviour, and ontogeny in the cichlid fish, Haplochromis piceatus: A study of morphological constraints in evolutionary ecology

AbstractI found evidence of a morphological constraint on the food choice of young stages of a cichlid fish. The constraint is not a developmental one because it is not imposed by developmental changes. I found no evidence of developmental constraints. In gradual transitions developmental constraints may be rare, in contrast to their regular occurrence in sudden transitions. I suggest that flexible muscle activation and reserve capacity (structural capacity in excess of functional demand) provide organisms with mechanisms that buffer against the effects of form changes and as such facilitate ontogenetic and evolutionary changes.A mathematical model for piercing prey in the pharyngeal jaws is applied to a juvenile cichlid fish. The maximum possible biting forces and the best biting directions were calculated. Piercing forces were measured that were generated when natural prey were pierced. The results were compared with the feeding behaviour in the laboratory and in the field and with results from an adult. The model predicts great flexibility of the pharyngeal jaw apparatus. Furthermore, the model predicts that a shift in biting point, prey size, or predator size leads to changes in muscle recruitment. The m.transversus ventralis is predicted to play an important role in pharyngeal biting.The model explains why large fish can easily pierce Chaoborus larvae and pupae, whereas a fish of 2.5 cm is just able to pierce larvae (symmorphosis) and is unable to pierce pupae. The inability of small fish to pierce pupae is due to a morphological constraint. This constraint is imposed by the size of the cross‐sectional areas of the muscles that generate the biting force. © 1993 Wiley‐Liss, Inc.

A model for biting in the pharyngeal jaws of a cichlid fish: Haplochromis piceatus

A mathematical model for piercing of prey in the pharyngeal jaws of a cichlid fish is presented to explain prey choice. The model allows simulation of static (pharyngeal) biting forces for various biting point locations and prey sizes. The maximum possible biting forces and the best biting directions were calculated using optimization techniques. The optimization criterion used was the minimization of the total muscular force that is necessary to generate the biting force. The system parameters for the model were obtained from a reconstruction of serial sections and from dissections of an adult Haplochromis piceatus. Experiments were carried out to determine the piercing forces that are generated when natural prey (Chaoborus sp. larvae and pupae) are pierced with a lower pharyngeal jaw. These results were compared with data on the feeding behaviour. The model predicts that at each specific biting point, biting forces can be generated in a range of directions. It predicts that a shift in biting point and or in prey size leads to changes in muscle recruitment. The results of the model clarify a number of morphological features: the twist of the fibres of the m.retractor dorsalis and the presence and position of the two m.m.levatores interni and the m.transversus ventralis. The predictions of the model explain in mechanistic terms an important aspect of the prey choice of H. piceatus in the field and in aquarium experiments.

Optimal foraging and ontogeny; food selection by Haplochromis piceatus.

We examined the influence of satiation level, prey density and light intensity on food uptake rate through the ontogeny of Haplochromis piceatus. Prey handling in the buccal cavity was found to be the main factor limiting prey uptake rate under light circumstances and at a sufficiently high prey density. Food uptake rate per unit body weight of different sizes of H. piceatus was equal when feeding on Chaoborus but decreased with increasing fish size when feeding on Daphnia magna. In choice experiments with Chaoborus and D. magna, prey selection by H. piceatus of all sizes was according to the predictions based on Charnov's 1976 model.

Prey Selection by Sight: Random or Economic?

Previous articleNext article No AccessNotes and CommentsPrey Selection by Sight: Random or Economic?Virginia C. MaioranaVirginia C. Maiorana Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 118, Number 3Sep., 1981 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/283838 Views: 3Total views on this site Citations: 10Citations are reported from Crossref Copyright 1981 The University of ChicagoPDF download Crossref reports the following articles citing this article:Marcelo V.C. Oliveira, Mario S. Dainez-Filho, Ana P.S. Bertoncin, Carolina M. Muniz, Thamis Meurer, Bruno R.S. Figueiredo, Sidinei M. Thomaz, Silvia Luciana Fávaro, Roger Paulo Mormul Native snails choose an invasive macrophyte over a native macrophyte as a food resource, Canadian Journal of Zoology 97, no.44 (Apr 2019): 362–367.https://doi.org/10.1139/cjz-2018-0116Juan Pablo Busso, Wolf U Blanckenhorn Viability selection by invertebrate predators in the polyphenic black scavenger fly Sepsis thoracica, Behavioral Ecology 29, no.44 (Apr 2018): 992–1000.https://doi.org/10.1093/beheco/ary039Douglas W. Whitman, Shawn Vincent Large size as an antipredator defense in an insect, Journal of Orthoptera Research 17, no.22 (Dec 2008): 353–371.https://doi.org/10.1665/1082-6467-17.2.353Pedro A Rincón, Javier Lobón-Cerviá Prey-size selection by brown trout ( Salmo trutta L.) in a stream in northern Spain, Canadian Journal of Zoology 77, no.55 (Oct 1999): 755–765.https://doi.org/10.1139/z99-031F. Galis, P. W. de Jong Optimal foraging and ontogeny; food selection by Haplochromis piceatus, Oecologia 75, no.22 (Mar 1988): 175–184.https://doi.org/10.1007/BF00378594Brian M. Marcotte, Howard I. Browman Foraging behaviour in fishes: perspectives on variance, Environmental Biology of Fishes 16, no.1-31-3 (Jun 1986): 25–33.https://doi.org/10.1007/BF00005157Paul C. E. Bailey The Feeding Behaviour of a Sit-and-Wait Predator, Ranatra dispar (Heteroptera: Nepidae): The Combined Effect of Food Deprivation and Prey Size on the Behavioural Components of Prey Capture, Ethology 71, no.44 (Apr 2010): 315–332.https://doi.org/10.1111/j.1439-0310.1986.tb00596.xBrian M. Marcotte, Howard I. Browman Foraging behaviour in fishes: perspectives on variance, (Jan 1986): 25–34.https://doi.org/10.1007/978-94-017-1158-6_2P. A. Cochran Size-selective attack by parasitic lampreys: consideration of alternate null hypotheses, Oecologia 67, no.11 (Aug 1985): 137–141.https://doi.org/10.1007/BF00378465Jay A. Blundon, Victor S. Kennedy Mechanical and behavioral aspects of blue crab, Callinectes sapidus (Rathbun), predation on Chesapeake Bay bivalves, Journal of Experimental Marine Biology and Ecology 65, no.11 (Nov 1982): 47–65.https://doi.org/10.1016/0022-0981(82)90175-7