African Journal of Marine Science最新文献

Eelgrass Zostera capensis populations in KwaZulu-Natal, South Africa, harbour distinct genomic signals despite limited geographical distance 南非夸祖鲁-纳塔尔省的鳗草 Zostera capensis 种群尽管地理距离有限，但却蕴藏着不同的基因组信号

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-12-08 DOI: 10.2989/1814232x.2023.2263503

SE Smit, R. Henriques, M. Jackson, R. Taylor, L. Vivier, S. von der Heyden

引用次数: 0

Allan Heydorn (1930-2023): marine biologist and conservationist 艾伦-海多恩（1930-2023）：海洋生物学家和保护主义者

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232x.2023.2291891

Rudy van der Elst, G. M. Branch

引用次数: 0

Network analysis of the endemic spotted gully shark Triakis megalopterus reveals spatial vulnerability to exploitation in the Western Cape, South Africa 对南非特有的斑沟鲨 Triakis megalopterus 的网络分析揭示了其在南非西开普省易受开发利用的空间脆弱性

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2271959

E. Cottrant, NJ Drobniewska, Thomas L Johnson, LG Underhill, T. Murray, N. Hammerschlag, PS Albano, C. Elston, ME McCord, P. Cowley, C. Fallows, TG Paulet

{"title":"Network analysis of the endemic spotted gully shark Triakis megalopterus reveals spatial vulnerability to exploitation in the Western Cape, South Africa","authors":"E. Cottrant, NJ Drobniewska, Thomas L Johnson, LG Underhill, T. Murray, N. Hammerschlag, PS Albano, C. Elston, ME McCord, P. Cowley, C. Fallows, TG Paulet","doi":"10.2989/1814232X.2023.2271959","DOIUrl":"https://doi.org/10.2989/1814232X.2023.2271959","url":null,"abstract":"The spotted gully shark Triakis megalopterus (Triakidae) is a mesopredatory species endemic to southern Africa. It is currently listed as Least Concern on the IUCN Red List in accordance with an estimated increase in population size, general release by recreational linefishers and incidental catches in the commercial linefisheries. Previous research suggests this species to be resident, and as such it is likely to receive protection in coastal marine protected areas (MPAs). However, its ecology and movement behaviour remain poorly studied. This study employed acoustic telemetry to provide information on the species’ movements along the coast of the Western Cape Province, South Africa. We used network analyses to investigate movement randomness, associations between individuals, sexual segregation, and the effectiveness of MPAs. Our findings reveal nonrandom movements as well as patterns of co-occurrence between individuals. Spatial network analysis suggested sexual segregation, because areas of high use (Walker Bay and De Hoop) differed between males and females. Co-occurrences were observed exclusively in Walker Bay, chiefly between males, with no co-occurrence found between females. The tagged spotted gully sharks were not detected extensively within existing MPA boundaries, though there was no significant difference between their movements inside and outside protected areas for both sexes.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"26 1","pages":"273 - 283"},"PeriodicalIF":1.2,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of rotational harvesting on the size composition of Cape rock oysters Striostrea margaritacea on the east coast of South Africa 轮采对南非东海岸开普岩牡蛎 Striostrea margaritacea 大小组成的影响

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2258936

E. Steyn, J. Groeneveld, J. Santos

{"title":"Effect of rotational harvesting on the size composition of Cape rock oysters Striostrea margaritacea on the east coast of South Africa","authors":"E. Steyn, J. Groeneveld, J. Santos","doi":"10.2989/1814232X.2023.2258936","DOIUrl":"https://doi.org/10.2989/1814232X.2023.2258936","url":null,"abstract":"A commercial fishery for the Cape rock oyster Striostrea margaritacea along the north coast of KwaZulu-Natal, South Africa (western Indian Ocean), follows a 4-year rotational cycle, with each harvest year followed by 3 fallow years across four harvest zones. We analysed reported harvesting effort and catch information, and fishery-independent oyster size composition data collected over 18 years (Feb 2003-Feb 2020), to investigate the sustainability of rotational harvesting. Total harvesting effort and catches declined over the study period, but on average, the number of oysters collected per outing increased. Fewer outings in recent years were attributed to incomplete reporting and a progressive loss of access to harvest sites. Generalised linear mixed models were used to estimate trends in oyster mean size in relation to fishing method (divers and intertidal collectors), harvest zone, 4-year rotational cycles, and months spent in a zone. Oyster mean size increased from north to south along the coast. Oysters caught by divers on newly exploited deeper reefs were initially larger than those caught by intertidal collectors. Mean oyster size decreased monthly during 1-year harvest periods but recovered to pre-harvest size over 3 fallow years. The results confirmed that the current rotational harvest strategy is well-suited to oyster biology and is sustainable at the present level of effort. Improved reporting on harvesting effort and catch are required to verify longer-term spatiotemporal trends in this fishery. More effective stakeholder communication is needed to resolve potential user conflict","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"21 1","pages":"249 - 258"},"PeriodicalIF":1.2,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Macrobenthic fauna of the Agulhas Bank shelf edge 阿古哈斯浅滩陆架边缘的大型底栖动物群

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2273362

S. Brandt, N. Karenyi, K. Sink

引用次数: 0

Marine macroalgae of the Agulhas Marine Province of South Africa: biodiversity, exploitation and potential for aquaculture 南非阿古哈斯海洋省的海洋大型藻类：生物多样性、开发利用和水产养殖潜力

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2262529

J. Bolton, C. McQuaid

{"title":"Marine macroalgae of the Agulhas Marine Province of South Africa: biodiversity, exploitation and potential for aquaculture","authors":"J. Bolton, C. McQuaid","doi":"10.2989/1814232X.2023.2262529","DOIUrl":"https://doi.org/10.2989/1814232X.2023.2262529","url":null,"abstract":"The Agulhas Marine Province (AMP) extends along most of the south coast of South Africa, from Cape Agulhas to the vicinity of the Mbashe River mouth in the Eastern Cape Province, and has its own distinctive warm-temperate seaweed flora, with high levels of diversity and endemism. Seaweed floras are excellent indicators of seawater temperature regimes and therefore very useful in studies of climate change. We provide new analyses of seawater temperatures for 50-km sections along this coast and discuss them in relation to upwelling mechanisms, with particular focus on Algoa Bay. The biogeography of the South African south coast/AMP seaweed flora is placed in a southern African context, and patterns of endemism are discussed. Commercial harvesting has involved only intertidal collection of Gelidium pristoides, but other species may have commercial potential. Seaweed aquaculture on this coast is currently limited to shore-based cultivation as abalone feed, but the potential for sea-based seaweed cultivation is discussed, with particular reference to Algoa Bay and the declared Algoa Bay Aquaculture Development Zone.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"10 1","pages":"221 - 234"},"PeriodicalIF":1.2,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geographical and seasonal patterns in the diet of Cape fur seals Arctocephalus pusillus pusillus in Namibia, based on extensive scat analyses 根据大量粪便分析得出的纳米比亚开普海狗（Arctocephalus pusillus pusillus）饮食的地理和季节模式

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2276789

DN Mwaala, MR Wilhelm, S. Kirkman, J-P Roux

{"title":"Geographical and seasonal patterns in the diet of Cape fur seals Arctocephalus pusillus pusillus in Namibia, based on extensive scat analyses","authors":"DN Mwaala, MR Wilhelm, S. Kirkman, J-P Roux","doi":"10.2989/1814232X.2023.2276789","DOIUrl":"https://doi.org/10.2989/1814232X.2023.2276789","url":null,"abstract":"Namibia's population of Cape fur seals Arctocephalus pusillus pusillus is a major constituent of top predator biomass in the northern Benguela upwelling system. Understanding their diet is key to comprehending their role in the ecosystem and potential drivers of recent population changes, such as a northward extension of the population's range. Using prey remnants retrieved from 1 413 scat samples collected monthly at 12 Cape fur seal colonies along the Namibian coast over 28 years (1994-2021), we assessed seasonal and geographical differences in their diet. We include the first comparison of diet between the growing colonies in the far northern area of Namibia and the colonies to the south, many of which have been in decline. Four fish species dominated in the diet. The bearded goby Sufflogobius bibarbatus, which is ubiquitous throughout the northern Benguela ecosystem, was the mostabundant prey item in the diet. However, Cape fur seals appeared to show a preference for the more-nutritious fish species Cape horse mackerel Trachurus capensis and the lanternfish Lampanyctodes hectoris by switching to those prey during autumn and spring in the north and south, respectively, coinciding with the greater availability of those species during upwelling periods. The availability of Cape horse mackerel, especially during a critical period for the growth and development of pups before the onset of winter, may be key to the greater productivity of Cape fur seal colonies in the north relative to those in the south of Namibia, and warrants further investigation. Juveniles of Cape horse mackerel and Cape hake Merluccius capensis were the only fishery species of commercial importance that were relatively abundant in the seals' diet, while the sardine Sardinops sagax, which was historically dominant, was found in negligible proportions.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"16 1","pages":"285 - 294"},"PeriodicalIF":1.2,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The changing status of important marine fishery species in selected South African estuaries 南非部分河口重要海洋渔业物种不断变化的状况

IF 1.2 4区生物学

African Journal of Marine Science Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2274899

A. Whitfield, BQ Mann

{"title":"The changing status of important marine fishery species in selected South African estuaries","authors":"A. Whitfield, BQ Mann","doi":"10.2989/1814232X.2023.2274899","DOIUrl":"https://doi.org/10.2989/1814232X.2023.2274899","url":null,"abstract":"This review examines the changing status of 10 estuary-dependent marine fish species in 10 South African estuarine systems, ranging from the Kosi Estuary in the northeast to the Berg Estuary in the southwest. In all of these systems, the selected fish species were found to be in population decline, but the causes of the declines varied from one system to another. Recreational and small-scale/subsistence fishing was a common pressure on fish stocks in most of the reviewed estuaries, but environmental degradation and pollution were the prime drivers for major population declines in the St Lucia and uMhlanga estuaries, respectively. Of six primary linefish species that have been well studied, two species are categorised as having an overexploited stock status and four species have reached a collapsed level where the spawner biomass per recruit (SBR) is now <25% of the original unimpacted level. Furthermore, two of those species (dusky kob Argyrosomus japonicus and white steenbras Lithognathus lithognathus) are in the 4‒6% SBR range and have been officially categorised as Endangered on the IUCN Red List. Unless definite steps are taken to reduce fishing pressure on the species discussed in this review, and successful policies put in place to promote healthy estuarine environments around the coast, estuarydependent fish stocks will continue to decline—to the detriment of the fish populations and the people who depend on fish for food, recreation and/or employment.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"17 1","pages":"235 - 248"},"PeriodicalIF":1.2,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139324585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Movement patterns of Natal seacatfish Galeichthys troworum (Ariidae) tagged in the Pondoland Marine Protected Area, Eastern Cape, South Africa 南非东开普省庞多兰海洋保护区内标记的纳塔尔海鱼运动模式

4区生物学

African Journal of Marine Science Pub Date : 2023-08-01 DOI: 10.2989/1814232x.2023.2242890

BQ Mann, K Cox, GL Jordaan, R Daly

{"title":"Movement patterns of Natal seacatfish Galeichthys troworum (Ariidae) tagged in the Pondoland Marine Protected Area, Eastern Cape, South Africa","authors":"BQ Mann, K Cox, GL Jordaan, R Daly","doi":"10.2989/1814232x.2023.2242890","DOIUrl":"https://doi.org/10.2989/1814232x.2023.2242890","url":null,"abstract":"AbstractA tag-recapture study was undertaken on the Natal seacatfish Galeichthys troworum in the Pondoland Marine Protected Area (PMPA) on the east coast of South Africa. A total of 473 fish were tagged over a period of 8 years, and 136 individuals (28.8%) were recaptured over a period of 16 years, some of them on multiple occasions. Most recaptures (82%) were caught within 200 m of their release site, with movements ranging between 0 and 617 m, and time-at-liberty ranging between 0 and 3 407 days (9.3 years). Data analysis showed that all recaptured fish remained in relatively small home ranges (of ∼360 m linear distance) and none of them abandoned their home range and moved out of the 2-km2 sampling blocks. While the no-take area of the PMPA provided effective protection for these fish, their relative abundance was similar in an adjacent exploited area. This is likely because G. troworum is not a desired linefish species, with most individuals caught being released, coupled with high post-release survival.Keywords: exploited areafork lengthhome rangesite fidelitystation-keepingtag and release","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135052471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Low hypoxia tolerance in larvae of the sardine Sardinops sagax and anchovy Engraulis encrasicolus may limit their stock recovery in the northern Benguela upwelling system 在本格拉北部上升流系统中，沙丁鱼sagax和凤尾鱼的低缺氧耐受性可能会限制其种群的恢复

4区生物学

African Journal of Marine Science Pub Date : 2023-08-01 DOI: 10.2989/1814232x.2023.2246056

A Kunzmann, RM Imam, SJ Geist

{"title":"Low hypoxia tolerance in larvae of the sardine Sardinops sagax and anchovy Engraulis encrasicolus may limit their stock recovery in the northern Benguela upwelling system","authors":"A Kunzmann, RM Imam, SJ Geist","doi":"10.2989/1814232x.2023.2246056","DOIUrl":"https://doi.org/10.2989/1814232x.2023.2246056","url":null,"abstract":"Physiological traits of five key fish species (Cape hake Merluccius spp., pelagic goby Sufflogobius bibarbatus, Cape horse mackerel Trachurus capensis, European anchovy Engraulis encrasicolus and sardine Sardinops sagax) from the northern Benguela upwelling system (NBUS) were compared during their larval stage by measurements of enzymatic activities of key metabolic enzymes (citrate synthase [CS] and pyruvate kinase [PK]). Two distinct age classes (early larvae: 8‒14 days old; late larvae: 22‒29 days old) for each species and from two areas were compared: Terrace Bay (20° S), the main spawning ground of Cape horse mackerel and anchovy, and Kunene (17° S), near the Angola–Benguela frontal zone, where warm and hypoxic water masses intrude into the NBUS. The results revealed significantly higher CS activity in both larval age classes in Cape horse mackerel, anchovy and sardine compared with Cape hake and pelagic goby. Pelagic goby and Cape horse mackerel had significantly higher PK activity compared with Cape hake, anchovy and sardine, apparent in both larval age classes and both areas. Results for anaerobic metabolism indicate higher capacity for pelagic goby and Cape horse mackerel to recover from oxygen debt built up in prey capture and predator escape behaviour and a higher potential for hypoxia tolerance when compared with Cape hake, anchovy and sardine. These results suggest higher survival probability for pelagic goby and Cape horse mackerel compared with the other species under conditions of a shoaling oxygen minimum zone and may explain their current dominance in the NBUS.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135054810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0