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Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa
Thesis (PhD)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613949770334208 |
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| access_status_str | Open Access |
| author | Schoeman, Stephanie |
| author2 | Simon, Carol A. |
| author_browse | Schoeman, Stephanie Simon, Carol A. |
| author_facet | Simon, Carol A. Schoeman, Stephanie |
| author_sort | Schoeman, Stephanie |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132443 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:16.501Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132443 Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa Schoeman, Stephanie Simon, Carol A. Matthee, Conrad A. Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. Population genetics Histology Plankton populations -- Effect of high temperatures on Diopatra aciculata -- Ecology Estuaries -- South Africa -- Knysna Genome-wide single nucleotide polymorphisms -- Variation UCTD Thesis (PhD)--Stellenbosch University, 2025. Schoeman, S. 2025. Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/89b1e60b-f188-469f-aeb1-527bd1d6f352 ENGLISH ABSTRACT: The estuarine moonshine worm, Diopatra aciculata, a popular bait polychaete species documented in three South African estuaries, was misidentified locally as the presumed cosmopolitan species, D. neapolitana. However, the species was reported in South Africa (1949) before it was described in Australia (1971), and therefore, its native range is uncertain. In Knysna, a protected area, D. aciculata is expanding in distribution and abundance despite being extensively used as bait, suggesting that life history traits allow the species to thrive. This study aimed to (1) determine the origin, fine-scale population structure, and dispersal of D. aciculata in South Africa using next-generation sequencing, and (2) investigate the life history patterns of D. aciculata. This study found that the D. aciculata population in Australia had a higher haplotypic diversity, suggesting that the Australian population is older and possibly the source of the South African population. Furthermore, significant population differentiation between South Africa and Australia (COI: FST = 0.2505; p < 0.05; SNPs: FST = 0.0782; p < 0.05) indicates a lack of gene flow between these populations, suggesting that the introduction was anthropogenic. The SNP analysis revealed population differentiation between Swartkops and the Graden Route, but no population differentiation between Knysna and Keurbooms indicates connectivity and bidirectional gene flow. Histology revealed that the species is the first documented gonochoristic member of the genus. Additionally, dribble spawning occurs annually through late winter (July – October), coinciding with an increase in water temperature. Moreover, larger oocytes were recorded from Knysna populations compared to Australian populations, which may increase the duration of the planktonic phase in Knysna and, in turn, increase dispersal. Furthermore, the annual dribble spawning may counter the loss of gametes and larvae due to the high flow rate (1000 to 2000 m³ per second) experienced in the estuary. Like other Diopatra species, D. aciculata is capable of anterior and posterior regeneration. However, while they can survive a certain level of damage, they are unable to survive the damage routinely inflicted during bait collection. Nevertheless, fishermen's consistent movement of bait to other estuaries can, under the right circumstances, contribute to the development of new populations and the species' anthropogenic dispersal. The genetic connectivity between Knysna and Keurbooms Estuaries indicates that water leaving the Knysna Estuary, and the planktonic larval phase is sufficient for the natural dispersal of the larvae to nearby estuaries. Furthermore, the continuous movement and discarding of even a few bait in other estuaries can lead to range expansion through incremental build-up, forming new populations if these fragments are large enough to regenerate. In light of these results, new management recommendations will include encouraging the use of the worms as bait by increasing the bag limit from 10 worms per person per day while discouraging bait movement from the estuary. AFRIKAANSE OPSOMMING: Die riviermond maanskynwurm, Diopatra aciculata, 'n gewilde aaspolychaete-spesie wat in drie Suid-Afrikaanse riviermondings gedokumenteer is, was plaaslik verkeerd geï dentifiseer as die kosmopolitiese spesie, D. neapolitana. Die spesie is egter in Suid-Afrika (1949) aangemeld voordat dit in Australie (1971) beskryf is, en daarom is sy naturlike verspreiding onseker. In Knysna, 'n beskermde gebied, toon D. aciculata drastiese groei en verspreiding, ondanks die feit dat dit wyd as lokaas gebruik word, wat daarop dui dat lewensgeskiedenis eienskappe die spesie laat floreer. Hierdie studie het die doel gehad om (1) die oorsprong, fynskaalse populasiestruktuur en verspreiding van D. aciculata in Suid-Afrika te bepaal deur gebruik te maak van volgende-generasie profilering, en (2) die lewensgeskiedenispatrone van D. aciculata te ondersoek. Hierdie studie het bevind dat die D. aciculata-bevolking in Australie 'n hoe r haplotipiese diversiteit het, wat daarop dui dat die Australiese bevolking ouer is en moontlik die bron van die Suid-Afrikaanse bevolking is. Verder dui betekenisvolle bevolkingsdifferensiasie tussen Suid-Afrika en Australie (COI: FST = 0.2505; p < 0.05; SNPs: FST = 0.0782; p < 0.05) op 'n gebrek aan geenvloei tussen hierdie populasies, wat daarop dui dat die bekendstelling antropogenies was. Die SNP-analise het bevolkingsdifferensiasie tussen Swartkops en die Tuinroete aan die lig gebring, maar geen bevolkingsdifferensiasie tussen Knysna en Keurbooms dui op konnektiwiteit en tweerigtinggeenvloei nie. Histologie het aan die lig gebring dat die spesie die eerste gedokumenteerde eengeslagtige lid van die genus is. Dribbelkruiting, wat saamval met 'n toename in watertemperatuur, vind jaarliks geduurened laat winter (Julie – Oktober) plaas. Boonop is groter oo siete vir die Knysna-bevolkings aangeteken in vergelyking met Australiese bevolkings, wat die duur van die planktoniese fase in Knysna kan verleng en verspreiding kan verhoog. Die jaarlikse dribbelkuiting kan die verlies van gamete en larwes die hoe vloeitempo (1000 tot 2000 m3 per sekonde) wat in die riviermond ervaar word, teenwerk. Soos ander Diopatra spesies, is D. aciculata in staat tot anterieur en posterieur regenerasie. Alhoewel hulle 'n sekere vlak van skade kan oorleef, is hulle egter nie in staat om die skade wat gereeld tydens aasversameling aangerig word, te oorleef nie. Nietemin kan vissermanne se konsekwente verskuiwing van aas na ander riviermondings, onder die regte omstandighede, tot die ontwikkeling van nuwe bevolkings en die spesie se antropogeniese verspreiding bydra. Die genetiese verbinding tussen Knysna- en Keurboomsriviermond dui daarop dat water wat die Knysnariviermond verlaat, en die planktoniese larwefase voldoende is vir die natuurlike verspreiding van die larwes na nabygelee riviermondings. Verder kan die voortdurende beweging en weggooi van selfs 'n klein hoeveelheid aas in ander riviermondings bydra tot uitbreiding van die populasie deur inkrementele opbou, wat nuwe populasies vorm as hierdie fragmente groot genoeg is om te herstel. In die lig van hierdie resultate sal nuwe bestuursaanbevelings die aanmoediging van die gebruik van die wurms as lokaas insluit deur die saklimiet van 10 wurms per persoon per dag te verhoog terwyl aasbeweging vanuit die riviermond te ontmoedig word. Doctoral 2025-06-09T05:53:30Z 2025-06-09T05:53:30Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132443 en Stellenbosch University xxi, 163 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Population genetics Histology Plankton populations -- Effect of high temperatures on Diopatra aciculata -- Ecology Estuaries -- South Africa -- Knysna Genome-wide single nucleotide polymorphisms -- Variation UCTD Schoeman, Stephanie Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title | Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title_full | Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title_fullStr | Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title_full_unstemmed | Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title_short | Origin, local dispersal, and reproductive patterns of the bait polychaete, Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae), in the Knysna Estuary, South Africa |
| title_sort | origin local dispersal and reproductive patterns of the bait polychaete diopatra aciculata knox and cameron 1971 annelida onuphidae in the knysna estuary south africa |
| topic | Population genetics Histology Plankton populations -- Effect of high temperatures on Diopatra aciculata -- Ecology Estuaries -- South Africa -- Knysna Genome-wide single nucleotide polymorphisms -- Variation UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132443 |
| work_keys_str_mv | AT schoemanstephanie originlocaldispersalandreproductivepatternsofthebaitpolychaetediopatraaciculataknoxandcameron1971annelidaonuphidaeintheknysnaestuarysouthafrica |