A detailed feeding study of eleven inshore top predatory teleosts in the eastern Cape is presented. Material collected largely from line-caught fish was augmented by spearfishing. The predators were grouped according to habitat: pelagic, soft-sediment demersal and reef species. Pelagic fish examined were Lichia amia, Pomatomus saltatrix, Seriola lalandi, Atractoscion aequidens, Katsuwonus pelamis and Thunnus albacares. Stomach content analyses revealed that their prey varied according to size and between species. In coastal areas important prey species were Sardinops ocellata, Etrumeus teres, Engraulis capensis and Loligo reynaudi. The use of fish otoliths and squid beaks allowed accurate identification of the prey and their measurement provided details of their size composition. This has provided greater insight into the distribution of prey species and their importance in food webs. The principal large predator of shallow coastal soft substrates is Argyrosomus hololepidotus, which takes pelagic and demersal prey. Important prey of small specimens are mysids, whereas fish and squid become more important in the diet of larger specimens (>300 mm). Fish prey include Sardinops ocellata, Engraulis capensis, Pomadasys olivaceum and A. hololepidotus. Loligo reynaudi is the dominant cephalopod prey. Selectivity of A. hololepidotus was investigated. Prey were compared to catches made during a small-mesh trawl survey. The absence of certain species from the diet suggests that they avoid predation, possibly by outswimming A. hololepidotus (e.g. P. saltatrix) while large Galeichthys feliceps are rare in the diet, probably because of their formidable spines. Flatfishes, P. olivaceum, juvenile G. feliceps and small A. hololepidotus appear to be preferred food items. The depth distribution of predators and prey is described, and it appears that the distribution of predators may be influenced by their prey. Top predatory teleosts inhabiting coastal reefs are Cheimerius nufar, Petrus rupestris, Polysteganus praeorbitalis and Epinephelus guaza. Diet changes with size and locality but comprises small reef fishes for most of the sparids. C. nufar takes pelagic fish and squid more than the other predators while P. rupestris and P. praeorbitalis prey on cheilodactylids, clinids and other reef associated prey predominantly. E. guaza takes principally crabs and octopods. Classification and ordination analyses of the prey taken illustrated the inter-relationships of predators, which change with increasing size. The pelagic predators are most similar to each other and A. hololepidotus is closer to this group than to reef predators. The reef predators are less similar to each other, although this group as a whole is segregated from pelagic predators. Exceptions to this are large C. nufar and large P. praeorbitalis, which fall into the pelagic predator group, as they took pelagic prey to a large extent. These results are discussed and the patterns shown are compared to other studies and current resource partitioning theory. Two food webs are provided for the coastal waters of the eastern Cape. The pelagic food web has clupeids, engraulids and L. reynaudi as principal components. The reef system is more complex and the Clinidae, Cheilodactylidae and Octopus spp. are important. The use of food webs in management and in providing a framework for testing theoretical models is shown to be important. Research needs are identified and include more detailed work on the basic biology and ecology of the top predators and their prey.

Thesis (Ph. D.)--Columbia University, 1901. / Slip with "Vita" inserted. Reprinted from the Memoirs of the New York Academy of Sciences, vol. II, pt. II, 1900. Bibliography: p. 80-84.

Inaugural-Dissertation - Strassbourg.

Thesis (doctoral)--Faculté de Sciences de Paris, 1884. / "Série A, no. 58, No. d'ordre 506." Includes bibliographical references (p. 79-80).

No description available.

The origin, function and evolution of the branchiostegal rays, the related opercular and gular bones and associated hyoid elements were investigated in teleostome fishes. Alizarin, skeletal or alcoholic specimens of over half the living families (over 240) and all the living orders of teleostome fishes with branchiostegals were examined. Literature provided data for most of line remaining living and fossil families and orders. Several evolutionary trends became apparent; a tendency for number of branchiostegals to decrease, following Williston's Law; increasing separation of mandibular and hyoid arches; and an increase in number and complexity of hyoid elements. In the development of hyoid elements, but not of branchiostegal rays, the ontogenetic sequence paralleled the phylogenetic sequence. Examination of the unusual adult hyoid relationships in the neotenic Schindleria showed it to resemble the larval condition of normal fishes. The condition in the tiny goby, Mistichthys, is similar. The structure of the branchiostegal series and hyoid elements proved valuable in tracing the relationships of fishes. Major findings include: Hiodontidae were found not be be closely related to the Notopteridae; the Notopteridae and osteoglossoid families to be related to the mormyriforms; the Neoscopelidae and Myctophidae to differ from other myctophiforms; the ophidioids to require ordinal separation from the Perciformes and placement near the Gadiformes and Ateleopiformes; the Amblyopsidae to belong in the Percopsiformes; the Anabantoidei and Ophicephaloidei to be closely related suborders of common ancestry deserving placement in the same order; the Beloniformes to differ from most other orders in the loss of the interhyal and upper hypohyal; and the Echeneiformes to differ from most Perciformes in the possession of 8-11 branchiostegals. The number of branchiostegals was found to be influenced by posterior extension of the jaws, small body length, feeding habits, gill membrane attachment and deepsea existence. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of this study was to elucidate some of the mechanisms involved in the control of the function of the fish heart. In vitro experiments were conducted to determine the effect of varying input pressure, temperature, and epinephrine concentration on the isolated, perfused, trout heart. In vivo experiments were conducted with chronically implanted flow probes to determine the effect of increased blood epinephrine levels on the activity of the heart of the lingcod. Five variables were measured to describe the activity of the isolated trout heart: rate, stroke volume, cardiac output, stroke work, and heart work per minute. Heart function curves were constructed showing the relationship between each of these variables and the input pressure at two levels of epinephrine, 0.1 ug/ml and 0.01 ug/ml, and at two temperatures, 6°C and 15°C. The isolated trout heart obeyed Starling's law, since the stroke work increased as the filling pressure, and thus the end diastolic fiber length, increased. Increased filling pressure also caused the heart rate to increase, probably due to a direct effect of pressure on the pacemaker cells. Increased temperature produced an increase in rate, which in turn decreased the filling time available between beats and so decreased the stroke volume. Cardiac output was not greatly affected by temperature changes. Low temperature appeared to have a direct inotropic effect on the heart as well; that is, greater stroke work was produced from a given end diastolic volume at low temperatures. Epinephrine had a pronounced inotropic effect at 15°C. The stroke volume, stroke work, cardiac output, and heart work per minute all increased with high epinephrine. The rate decreased, probably because the systolic emptying was so much more complete that a greater time interval between beats was needed to fill the heart. At 6°C the inotropic effect of low temperature masked the inotropic effect of epinephrine, so that high epinephrine produced no change in stroke work or stroke volume. A positive chronotropic effect was pronounced at this temperature. The cardiac output and heart work per minute increased with epinephrine as a result. The adrenergic receptors mediating the responses of the heart to epinephrine were of the β-type only. The responses were blocked by Inderal, a β-receptor blocking agent, but were unaffected by phenoxybenzamine, an ⍺-receptor blocking agent. Increased levels of epinephrine in the blood of the lingcod at 10° - 12°C produced an increase in the mean blood flow in the ventral aorta. The heart rate remained constant, thus the changes in mean blood flow were due to changes in stroke volume. These stroke volume changes could be produced by epinephrine acting on the heart directly via β-receptors in the myocardium or indirectly via changes produced in the rest of the circulatory system. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.Sc. (Zoology)) -- University of Limpopo , 2023 / Currently Copepoda consists of 14 600 species of which 2 275 species are members of the Siphonostomatoida. Siphonostomatoida consists of 40 families, with 17 families symbiotic on fish. Sphyriidae has 44 accepted species in eight reported genera, of which four genera infect teleosts and the remaining four infect elasmobranchs. Adult females undergo transformation through loss of locomotory appendages to suit their mesoparasitic lifestyle and develop outgrowths on the cephalothorax or neck for attachment to the host. To date, only 176 marine siphonostomatoid species have been reported from South African waters, with only nine sphyriid species. Sphyriids previously collected from marine bony fish off the east, south and west coasts of southern Africa and preserved in 70% ethanol were studied. Specimens were examined with stereo- and compound microscopes and identified using published literature. Selected specimens were stained in lactic acid with added lignin pink, appendages were dissected and illustrated with the aid of a drawing tube. Selected specimens were also studied through scanning electron microscopy. The examined specimens were identified as species of Sphyrion and Lophoura. Re descriptions were done for all valid Sphyrion species females (S. laevigatum, S. lumpi and S. quadricornis) and new descriptions for the males of S. laevigatum and S. quadricornis. Post-metamorphosis females of Sphyrion species can be differentiated by the shape of cephalothorax, length of the neck in relation to the length of the trunk and the length of posterior processes in relation to the trunk length, while males are mostly very similar. New information is provided regarding the appendages of S. laevigatum and S. quadricornis. The appendages of the three species bear close resemblance to one another. Additionally, an identification key for the post metamorphosis females of Sphyrion species is provided. Re-descriptions were done for five female Lophoura species (L. caparti, L. cornuta, L. cf edwardsi, L. tetraloba and Lophoura sp.) and a new description of the male of L. tetraloba. Differences between young and post-metamorphosis females of L. cf edwardsi and L. tetraloba were observed in the width of the holdfast organ processes and the length of porous peduncle and stalks of the posterior processes which appear to grow with age. The difference between the young and adult male of L. tetraloba lies in the lengths of the cephalothorax in relation to the trunk length and segmentation visible on the trunk of the young male but not adult male. The post-metamorphosis females of Lophoura species can be differentiated by the shape and number of processes on the holdfast organ, in combination with the cephalothorax length in relation to the neck length, neck length in relation to the trunk length, shape of the trunk, and the length and structure of the posterior processes. An identification key was drawn up for all species of the Lophoura post-metamorphosis females. An attempt was made to provide the COI barcodes for all the species of Sphyrion and five species of Lophoura. These would have confirmed the species identification of morphologically variable species e.g. S. laevigatum and S. lumpi and also provide an estimation of the interspecific divergence amongst the different species. Additionally, it would have assisted in distinguishing between L. tetraloba and L. cf edwardsi and provided an estimation of the amount of sequence divergence between the two genera. Unfortunately sequencing of apparently successfully amplified products was unsuccessful probably due to low DNA quality which possibly degraded due to collection methods used for the fish hosts and parasites and prolonged preservation of specimens. This study provides new host records i.e. Coelorinchus simorhynchus, Coelorinchus trunovi and Saurida undosquamis for Sphyrion quadricornis off South Africa which is also a new geographical record. Allocyttus verrucosus, Coelorinchus simorhynchus, Coelorinchus trunovi, Mesovagus antipodum and Ventrifossa nasuta are also new host records for S. lumpi. Additionally, Epigonus denticulatus and Bassanago albescens are new host records for Lophoura caparti and L. cornuta respectively off South Africa, which is a new geographical record for both species. Furthermore, Coelorinchus fasciatus and Lucigadus ori are new host records for Lophoura tetraloba and L. cf edwardsi off South Africa, which is also a new geographic record for both species. Thus, the results of the study improve the current knowledge of the marine siphonostomatoid biodiversity off South Africa as well as their distribution and infected hosts. / National Research Foundation (NRF)

In higher vertebrates, normal digestion and absorption by the gastrointestinal tract are dependent on the orderly and controlled transit of intraluminal contents. A relationship between fluid passage through the gut and absorption from the gut has yet to be examined in fish. In marine teleosts, the osmolality and ion concentration of the ingested seawater (SW) must be lowered before water absorption is initiated. By assuming that these processes are related to fluid transit, it is likely that alterations in these processes as well as in the water-electrolyte balance (WEB) of the animal would result with changes in the transit of intraluminal fluid. I hypothesized that marine teleosts regulate gut motility to achieve essential water absorption and thereby maintain the WEB. To test this, the gut of a marine teleost, the buffalo sculpin (Enophrys bison G.), was challenged in situ with forced drinking (continuous perfusion) at rates above and below that of the measured drinking rate (DR). Initially, the sensitivity of the WEB of the sculpin to preparatory manipulations that were essential for testing the above proposal was determined. The WEB was monitored before, during and after manipulation that included handling, containment, benzocaine-induced anesthesia, arterial and esophageal cannulation and serial sampling of blood. To monitor the WEB, indicators of the osmotic status and the intravascular volume were measured. Within one to three hours after surgery, a hyper-osmotic hemodilution resulted from an influx of hyper-osmotic fluid. Blood volume increased about 18% after surgery. The osmotic imbalance was corrected within 24 hours after surgery, whereas, the volume disturbance persisted. The occurrence of plasma hyper-osmolality after surgery was inhibited with esophageal occlusion. This implicated the gut as the origin of the osmotic and volume disturbances. Further data evaluation suggested that the surgery-induced WEB disturbance was a resultant of enhanced ion and water absorption in the upper and lower gut. Next, the DR and drinking behavior of the buffalo sculpin were determined. Also assessed was the influence of the manner of SW ingestion (ab libitum drinking or forced drinking) and of the rate of ingestion on SW modification by the gut. DR was variable within as well as among experimental groups. DR appeared to increase with the animal's capture duration suggesting that water permeability of the sculpin was gradually increasing after capture. The fluid volume and resident duration, and water modification in the upper gut and lower gut were consistent over a broad range of DRs. This demonstrated that the sculpin were ingesting SW frequently, perhaps in a manner similar to sipping. In respect to estimates made in sculpin allowed to drink ab libitum, forced drinking had a negative effect on desalting. Finally, a relationship was looked for between gut motility and the WEB of the sculpin. Several indicators of gut motility, water absorption, and the WEB were monitored while the gut was perfused at several different rates. If gut motility is regulated to achieve essential water absorption, then changes in gut motility would result in response to alterations in the forced drinking rate, so that adequate water modification and absorption would be accomplished and the WEB maintained. Over the levels of perfusion administered, the WEB was not maintained. With the elevation in perfusion rate, the intravascular volume increased and yet intestinal water absorption was maintained or gradually increased. It appears that under the circumstance of enhanced SW ingestion, the mechanisms regulating gut motility and water absorption are not integrated with mechanisms maintaining the WEB of the buffalo sculpin. It remains unclear if, without SW ingestion, gut motility and the WEB are actively related. / Graduation date: 1982

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: David P. M. Northmore, Dept. of Psychology. Includes bibliographical references.