Full and FINAL MASTERS DISCERTATION
Total Page:16
File Type:pdf, Size:1020Kb
ASPECTS OF THE MORPHOLOGY AND ECOLOGY OF A DIPLOZOON SPECIES (MONOGENEA) FROM THE GILLS OF LABEO UMBRATUS IN THE VAAL DAM AND VAAL RIVER BARRAGE, GAUTENG, SOUTH AFRICA. LAURETTE SEDDON Supervisor: Prof. A. Avenant-Oldewage Dissertation submitted in partial fulfilment of the requirements for the degree Master of Science in Zoology in the Faculty of Science of the Rand Afrikaans University Johannesburg , May 2004 ABSTRACT To date, 4 diplozoidae parasites have been described form Africa. Two belonging to the genus Diplozoon, namely D. aegyptensis and D. ghanense from sites in Northern Africa. One belonging to the genus Neodiplozoon, namely Neodiplozoon polycotyleus . The fourth monogenean is the concern of this study which aimed to determine the exact classification of the monogenean found on the gills of Labeo umbratus in the Vaal Dam and Vaal River Barrage respectively. The study was conducted over a 13-month period, with field data collections occurring every two to three months from January 1999 to February 2000. Host fishes were collected with the aid of gill nets with mesh sizes of 90, 110 and 130mm respectively. In-field measurements were taken regarding the total length, fork length, position of parasites on the gill arches and the host gender. All parasites collected were fixed in steaming AFA and stored in 70% ethanol. Laboratory measurements of whole mounts were completed with the aid of light microscope and drawing tube attachment. Staining methods employed included Boraxcarmine-iodine, Mayer’s Hematoxylin and Horen’s Trichrome. Scanning electron microscopy was used to gather information regarding the external morphology of the parasites. Both critical point drying and freeze drying preparation methods were used. For the investigation of the internal morphology serial sections of 5µm were made and stained with AZAN. Graphic reconstruction was completed using standard methods. All data collected was statistically analysed by the use of the SPSS (windows version 10.0) computer programme. Quantitative results showed greater prevalence in larger hosts, a preference for male hosts, no preference for attachment site, prevalence correlation to temperature only at the Vaal Dam site, prevalence correlation to pH values of the water, negative correlation between presence of parasite and host condition factor. The environmental factor proving to have the greatest impact is the turbidity levels. Measurement results are as follows: a total of 135 parasites were collected i from 50 hosts. Measurements were taken from 62 parasites, equalling 46% of the total sample size. Data was obtained regarding the anterior length, posterior length, and total length of 57 parasites. The opisthaptor size (N=72) was length 190mm - 1000mm; width 50mm - 1000mm; the suckers (N=118) measured length 50mm - 150mm; width 50mm - 150mm. Between the left and right opisthaptor clamps, 1st clamps (N = 81) measured length 20mm - 110mm; width 70mm - 150mm, 2nd clamps (N = 83) with length 30mm - 100mm; width 50mm - 150mm, 3rd clamps (N = 82) with length 40mm - 90mm; width 40mm - 160mm and 4th clamps (N = 76) with length 10mm - 110mm; width 50mm - 150mm. No measurements could be made of clamp internal characteristics. Body of central hook 8 - 13µm in length, handle of central hook 2 - 5µm long. Only 7 eggs were measured with length 220 - 350µm and width 90 - 100µm. No diporpa larvae were collected. Graphic reconstruction confirmed the location of the reproductive organs in a ventral position in the body with the digestive tract occupying the dorsal region. Comparisons were made between the measurements obtained during this study, and measurements from other members of the genus Diplozoon and Paradiplozoon from both Africa and Europe. It is shown that although there is a certain measure of overlapping morphological sizes, physical structures distinguish it from other species and this is elucidated. The parasite dealt with in this study therefore is described here-in as a new species namely Diplozoon plicati. KEYWORDS: Monogenea, Diplozoon, Africa, Vaal River system, morphological measurements, condition factor, description, Labeo umbratus . ii OPSOMMING Tot op hede is 4 verteenwoordigers behorende tot die Diplozoidae vanuit Afrika beskryf. Twee het tot die genus Diplozoon behoort, naamlik D. aegyptensis en D. ghanense vanaf Noord-Afrika. ‘n Derde een het tot die genus Neodiplozoon behoort, naamlik Neodiplozoon polycotyleus . Die vierde verteenwoordiger van die Monogenea is die fokus punt van hierdie studie wat poog om die taksonomie van die verteenwoordiger van die Monogenea op te klaar soos op die kieue van Labeo umbratus gevind is in die Vaaldam en Vaalrivierbarrage onderskeidelik. Die studie is uitgevoer oor ‘n tydperk van 13 maande met veldopnames wat elke twee tot drie maande vanaf Januarie 1999 tot Februarie 2000 plaasgevind het. Gasheervisse is met behulp van kieunette met maasgroottes van 90, 110 en 130mm onderskeidelik versamel. Afmetings met betrekking tot totale lengte, vurklengte, posisie van parasiet op kieue asook geslag van gasheer is geneem. Alle parasiete wat versamel is is in stomende AFA gefikseer en in 70% etanol gestoor. Afmetings van totaalpreparate is met behulp van ‘n ligmikroskoop en tekenbuisapparaat bestudeer. Boraks-Karmyn Jodium, Mayer se Hematoksalien en Horen se trichroom kleuring is gebruik vir die maak van preperate . Skandeerelektronmikroskopie is uitgevoer om inligting aangaande die uitwendige morfologie van die parasiete te versamel. Beide kritieke puntdroging en vriesdroging voorbereidingstegnieke is toegepas. Vir die ondersoek van die interne morfologie is seriesneë van 5µm gemaak en met AZAN gekleur. Grafiese rekonstruksie is voltooi deur die gebruik van standaard metodes. Alle data is statisties ontleed deur die SPSS (Windows weergawe 10.0) rekenaarprogram. Kwantitatiewe resultate dui op groter persentasie besmetting in groter gashere, ‘n voorkeur vir mannetjies, geen voorkeur vir posisie van aanhegting en ‘n persentasie besmetting korrelasie met temperatuur. Slegs by die Vaaldam studie area bestaan daar ‘n persentasie besmettings korrelasie met die pH waardes van die water. ‘n iii Negatiewe korrelasie tussen die aanwesigheid van parasiete en die gasheer se kondisiefaktor is gevind. Die omgewings faktor wat blyk die grootste invloed te hê is turbiditeitsvlakke. Resultate is as volg: ‘n totaal van 135 parasiete is versamel van 50 gashere. Afmetings is geneem van 62 parasiete, gelykstaande aan 46% van die totale monstergrootte. Data met betrekking tot die anterior lengte, posterior lengte en totale lengte is verkry. Die opisthaptorgroottes (N=72) wys 190mm - 1000mm; wydte 50mm - 1000mm; die suiers (N=118) se lengte 50mm - 150mm; wydte 50mm - 150mm. Afmetings van die linker en regter opisthaptorklampe , 1ste klampe (N = 81) lengte 20mm - 110mm; wydte 70mm - 150mm, 2de klampe (N = 83) lengte 30mm - 100mm; wydte 50mm - 150mm, 3de klampe (N = 82) lengte 40mm - 90mm; wydte 40mm - 160mm en 4de klampe (N = 76) lengte 10mm - 110mm; wydte 50mm - 150mm. Geen afmetings kon gemaak word van interne klampstrukture nie. Liggaam van sentrale haak is 8-13µm lank en handvatsel meet 2-5µm lank (N = 8). Slegs 7 eiers is gemeet en die lengte was 220 - 350µm met wydte 90 - 100µm. Geen diporpa larwes is versamel nie. Grafiese rekonstruksies bevestig die posisie van die voortplantingsorgane wat ventraal in die liggaam geleë is met die spysverteringskanaal wat die dorsale area beslaan. Vergelykings is gemaak tussen die afmetings verkry gedurende hierdie studie en afmetings van ander lede van die genus Diplozoon en Paradiplozoon vanaf beide Afrika en Europa. Dit word gewys dat alhoewel daar ‘n sekere mate van oorvleuling van afmetings is, daar morfologiese strukture is wat dit onderskei van ander spesies. Die parasiet in hierdie studie bespreek, is beskryf as ‘n nuwe spesie naamlik Diplozoon plicati . SLEUTELWOORDE: Monogenea, Diplozoon, Vaalrivierstelsel, morfologiese afmetings, kondisiefaktor, beskrywing, Labeo umbratus . iv DECLARATION I hereby declare that this report is my own original work. It is submitted in partial fulfilment of the requirements for the degree Master of Science in the Faculty of Science of the Rand Afrikaans University, Johannesburg, Gauteng, South Africa. It has never been submitted before for any other degree or examination at any other university or academic institution. _________________________________________ Laurette Seddon v ACKNOWLEDGEMENTS With sincere thankfulness to: ô My supervisor, Prof. Avenant-Oldewage for all her patience, guidance, ongoing encouragement and financial support. ô Professor Swanepoel ex of Rand Afrikaans University Zoology Department for his translation of Khotenovsky’s keys to the Diplozoidea family and the description of Diplozoon paradoxum. ô Mrs. Edie Lutsch of Zoology Department of the Rand Afrikaans Unive rsity for her guidance in producing microtome sections as well as with staining procedures. ô The National Research Foundation, Pretoria, for their financial support of this project. ô My immediate family, without whose support I could not have successfully completed this project. vi INDEX ABSTRACT..................................................................................i KEYWORDS.......................................................................ii OPSOMMING...............................................................................iii SLEUTELWOORDE.............................................................iv DECLARATION............................................................................v