{"refrec":{"BRefID":12788,"RR":"<b>Bollen, A.</b> (1993). <i>Saccostrea cucullata</i> (von Born, 1778): voedselaanwezigheid in een mangrovekreek (Gazi, Kenya) = <i>Saccostrea cucullata</i> (von Born, 1778): food availability in a mangrove creek (Gazi, Kenya). MSc Thesis. Vrije Universiteit Brussel: Brussel.  105 pp.","BEntID":12788,"PublicFlag":1,"CheckedFlag":0,"wosflag":null,"vabbflag":null,"RefStringPartII":". MSc Thesis. Vrije Universiteit Brussel: Brussel.  105 pp.","DocTypID":5,"DocType":"Book/Monograph","MarineFlag":0,"FreshFlag":0,"BrackishFlag":1,"TerrestrialFlag":0,"Authorstring":"Bollen, A.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Bollen, A.","Englishabstract":"In this study is checked whether morphological differences of the mangrove oyster <i>Saccostrea cucullata</i> (von Born, 1778) can be explained by its food supply. In the first part the theoretical amount of food available for <i>Saccostrea cucullata</i> in Gazi (Kenya) is determined, in the form of zooplankton, phytoplankton, particulate organic matter (POC and chlorophyll a) and dissolved organic carbon (DOC). By means of ANOVA we showed that there are few significant differences in the ration of three of these four variables (zooplankton, phytoplankton, particulate organic matter) as a function of the tide. This means that any differences in food availability for <i>Saccostrea cucullata</i> are a result of the difference in immersion time, caused by the different heights above chart datum at which the oysters grow. Zooplankton and DOC seem to be abundant in Gazi bay (resp. 4,5x104 to 8,0x105 ind./l, and 5,44 to 5,94 mg/l), POC and total seston show the same amount as in other coastal are as (resp. 0,373 to 1,376 mg/l, and 12,55 to 20,55 mg/l), and phytoplankton and chlorophyll a are present in very low concentrations (resp. 1,7x103 to 1,9x105 cells/l, and 0,055 to 0,298 µg/l). Carbon isotope analysis showed that <i>Saccostrea cucullata</i> filters detritus from mangrove leaves and from seagrasses, but stomach analysis also gave certainty about intake of diatoms and dinoflagellates. The findings on DOC-concentrations do not exclude the intake of DOC by <i>Saccostrea cucullata</i>. The daily ration of <i>Saccostrea cucullata</i> in Gazi creek, respectively on the highest and the lowest level, appear to be highest for DOC (5,5 and 211,9 %), followed by POC (1,3 and 49,1 %) and finally zooplankton (0,07 and 2,5 %) and phytoplankton (0,004 and 0,2 %). In the second part of this study we tested (by means of ANOVA and linear regression) the hypothesis that the theoretical amount of food available, as derived from the height above chart datum, is related to the morphological differences of the oysters within the oyster culture in Gazi bay, expressed in lengths and dry weights of the organs. First we showed with ANOVA that formaline has almost no influence on the sizes and the weights of oyster organs. Our results also show that all measured organs are linearly correlated with the shell length, but that the height above chart datum does not show any linear correlation with the shell length. One of the most important findings of this study is that there are no apparent differences in organ sizes of <i>Saccostrea cucullata</i> whether it is growing high or low above chart datum, while there is a large difference in potential feeding time, with always about the same food availability.","AbstractOtherLang":"In deze studie wordt onderzocht of morfologische verschillen bij de mangroveoester <i>Saccostrea cucullata</i> (von Born, 1778) verklaarbaar zijn door de voedselaanwezigheid. In een eerste gedeelte wordt de theoretische hoeveelheid beschikbaar voedsel voor <i>Saccostrea cucullata</i> in Gazi kreek (Kenya) onderzocht, onder de vorm van zooplankton, fytoplankton, particulair organisch materiaal (POC en chlorofyl a) en opgelost organisch koolstof (DOC). Door middel van ANOVA wordt aangetoond dat er weinig significante verschillen zijn in het voedselaanbod van drie van deze vier variabelen (zooplankton, fytoplankton en particulair organisch materiaal) in functie van het getij. Dit houdt in dat de verschillen in voedselbeschikbaarheid voor de oester <i>Saccostrea cucullata</i> enkel worden veroorzaakt door de verschillen in onderdompelingstijd, veroorzaakt door de verschillende hoogtes ten opzichte van de referentie waarop de oesters groeien. Zooplankton en DOC blijken in Gazi kreek overvloedig aanwezig (resp. 4,5x104 tot 8,0x105 ind./l, en 5,44 tot 5,94 mg/l), POC en totaal seston vertonen dezelfde hoeveelheid als in andere kustgebieden (resp. 0,373 tot 1,376 mg/l, en 12,55 tot 20,55 mg/l), en fytoplankton en chlorofyl a zijn in zeer lage concentratie aanwezig (resp. 1,7x103 tot 1,9x105 cellen/l, en 0,055 tot 0,298µg/l). Met behulp van koolstofisotopenanalyse wordt aangetoond dat <i>Saccostrea cucullata</i> zowel detritus afkomstig van mangrovebladeren als van zeegrassen opneemt, maar maaganalyse gaf ook zekerheid over de opname van diatomeeën en dinoflagellaten. De bevindingen in verband met DOC-concentraties sluiten niet uit dat <I>Saccostrea cucullata</I> ook DOC opneemt. De daily ration van <i>Saccostrea cucullata</i> in Gazi kreek, resp. op het hoogste en het laagste niveau, blijkt het hoogst voor DOC (5,5 en 211,9 %), dan volgt POC (1,3 en 49,1 %) en tenslotte zooplankton (0,07 en 2,5 %) en fytoplankton (0,004 en 0,2 %). In een tweede gedeelte wordt (door middel van ANOVA en lineaire regressie) de hypothese getest dat de theoretische hoeveelheid beschikbaar voedsel, onder de vorm van de hoogte ten opzichte van de referentie, in relatie staat tot de morfologische verschillen bij de oesters uit de oesterkwekerij in Gazi kreek, uitgedrukt in lengten en drooggewichten van de organen. Eerst wordt met een ANOVA-toets aangetoond dat formol bijna geen invloed heeft op de afmetingen en gewichten van oesterorganen. Uit onze resultaten blijkt ook dat alle gemeten organen lineair gecorreleerd zijn met de schelplengte, maar dat de hoogte boven referentie geen lineaire correlatie vertoont met de schelplengte. Eén van de belangrijkste vindingen van deze studie is dat er geen aantoonbare verschillen zijn in orgaangroottes bij <I>Saccostrea cucullata</I> groeiend hoog boven referentie of lager in de getijdenzone, terwijl er een groot verschil in potentiële voedingstijd is, met steeds ongeveer dezelfde voedselbeschikbaarheid.","BibLvlCode":"M","StandardTitle":"<i>Saccostrea cucullata</i> (von Born, 1778): voedselaanwezigheid in een mangrovekreek (Gazi, Kenya) = <i>Saccostrea cucullata</i> (von Born, 1778): food availability in a mangrove creek (Gazi, Kenya)","OrigTitleLangCode":"nl","OrigTitleLangCodeExtended":"dut","OrigTitleLangID":41,"DateLastModified":{"date":"2025-07-02 08:33:14.980000","timezone_type":1,"timezone":"+00:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"Kenya-Belgium project","OtherDescriptors":null,"Notes":null,"AnaPub":null,"MonPub":1993,"DateUpdate":"2013-08-05","DateCreate":"2001-07-04","SecASFANote":null,"ConfID":null,"PeerRev":null,"VlizCoreFlag":1,"WoScode":null,"VABBcode":null,"OpenAcc":0},"refs":null,"anarec":null,"monrec":{"MonID":12788,"ISBN":null,"PubliDate":1993,"IssueDate":null,"Volume":null,"Issue":null,"Pagination":"105","Place":"Brussel","Edition":null,"BRefXtra":null,"BRefXtraRR":null,"SerID":null,"SerRR":null,"Ser2BRefID":null,"Ser2RR":null,"StandardTitleSer":null,"ISSN":null,"AbbrevSer":null,"Degree":"MSc","ThesisID":12788,"InsID":1555,"Acronym":"WE","FullStandardName":"Vrije Universiteit Brussel; Faculteit Wetenschappen & Bio-ingenieurswetenschappen","ToPubliDate":null,"SerNotes":null,"eISBN":null,"Pages":105},"serrec":null,"relations":null,"relationsRev":null,"addrec":null,"othpubs":null,"ownerships":null,"authors":[{"AutName":"Bollen","Firstname":"An","Initials":"A.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":12788,"AutID":16712,"OrderNr":1,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":28445,"InsID":null}],"mapdetails":null,"datasets":[{"DasID":5396,"Acronym":null,"Citation":"Bollen A.; Polk P.; Faculteit Wetenschappen; Laboratorium voor Ecologie en Systematiek. 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