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Distribution and site fidelity of four endemic catshark species in Walker Bay, South Africa 南非沃克湾四种特有鲶鲨的分布和地点忠诚度
IF 1.2 4区 生物学 Q3 Agricultural and Biological Sciences Pub Date : 2024-02-13 DOI: 10.2989/1814232x.2023.2278620
Thomas L Johnson, JC de Bresser, E. Cottrant, NJ Drobniewska, TG Paulet, LG Underhill
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引用次数: 0
Distribution and site fidelity of four endemic catshark species in Walker Bay, South Africa 南非沃克湾四种特有鲶鲨的分布和地点忠诚度
IF 1.2 4区 生物学 Q3 Agricultural and Biological Sciences Pub Date : 2024-02-13 DOI: 10.2989/1814232x.2023.2278620
Thomas L Johnson, JC de Bresser, E. Cottrant, NJ Drobniewska, TG Paulet, LG Underhill
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引用次数: 0
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 Q3 Agricultural and Biological Sciences 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
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232x.2023.2291891
Rudy van der Elst, G. M. Branch
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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 Q3 Agricultural and Biological Sciences 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
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.
斑沟鲨(Triakis megalopterus)是南部非洲特有的中型食肉鱼种。根据估计的种群数量增长、休闲延绳钓渔民的普遍放生以及商业延绳钓渔场的意外捕获,该物种目前在世界自然保护联盟红色名录中被列为最不关注物种。以前的研究表明,该物种是常住物种,因此可能会受到沿海海洋保护区(MPAs)的保护。然而,对其生态学和移动行为的研究仍然很少。本研究利用声学遥测技术提供了该物种在南非西开普省沿海的活动信息。我们使用网络分析来研究其移动的随机性、个体之间的关联、性隔离以及海洋保护区的有效性。我们的研究结果揭示了非随机运动以及个体间的共存模式。空间网络分析表明存在性隔离,因为雄性和雌性的高使用率区域(沃克湾和德霍普)是不同的。只在沃克湾观察到雄性之间的共同出现,没有发现雌性之间的共同出现。在现有的海洋保护区范围内没有广泛地发现被标记的斑点叉尾鲨,尽管雌雄斑点叉尾鲨在保护区内外的活动没有显著差异。
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2258936
E. Steyn, J. Groeneveld, J. Santos
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
南非夸祖鲁-纳塔尔省(西印度洋)北海岸对开普岩牡蛎 Striostrea margaritacea 的商业捕捞采用 4 年轮作周期,在四个捕捞区中,每个捕捞年之后有 3 个休渔年。我们分析了报告的捕捞努力量和渔获量信息,以及 18 年来(2003 年 2 月至 2020 年 2 月)收集的独立于渔业的牡蛎大小组成数据,以研究轮捕的可持续性。在研究期间,总捕捞努力量和渔获量有所下降,但平均每次出海采集的牡蛎数量有所增加。近年来出海次数减少的原因是报告不完整和捕捞地点的逐渐丧失。使用广义线性混合模型估算了牡蛎平均大小与捕捞方法(潜水员和潮间带采集者)、捕捞区、4 年轮换周期和在捕捞区停留的月数有关的趋势。牡蛎的平均大小沿海岸线由北向南增加。潜水员在新开发的深礁上捕获的牡蛎最初比潮间带采集者捕获的大。牡蛎的平均大小在为期 1 年的捕捞期逐月减小,但在 3 年的休渔期又恢复到捕捞前的大小。结果证实,目前的轮捕策略非常适合牡蛎生物学,在目前的捕捞水平下是可持续的。需要改进对捕捞努力量和渔获量的报告,以核实该渔业的长期时空趋势。需要与利益相关者进行更有效的沟通,以解决潜在的用户冲突。
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2273362
S. Brandt, N. Karenyi, K. Sink
The deep sea (>200m depth) off South Africa is largely unexplored, with most benthic macrofauna samples limited to depths shallower than 100m. The benthic infaunal diversity of the Agulhas Bank shelf edge has not yet been studied. We analysed seven grab samples that were opportunistically collected along the shelf edge at depths of 290-533 m. A total of 136 macrofauna items representing 75 species were identified, and the first species list of the infauna of the shelf edge was compiled, Polychaetes comprised 48% of total abundance, and the sites had an average similarity of 7% based on species abundance, Spearman rank correlation showed that depth and sediment particle size are important environmental drivers of community abundance and biomass variation on the shelf edge, Habitat heterogeneity is likely high along the Agulhas Bank shelf edge, Greater sampling effort in habitats for which data are scarce provides crucial information for offshore biodiversity assessment and management
南非近海的深海(深度大于 200 米)大部分尚未开发,大多数底栖大型动物样本仅限于浅于 100 米的深度。阿古哈斯浅滩大陆架边缘的底栖生物多样性尚未得到研究。我们分析了在大陆架边缘水深 290-533 米处随机采集的七个抓取样本。多毛类占总丰度的 48%,根据物种丰度,各地点的平均相似度为 7%、斯皮尔曼等级相关性表明,深度和沉积物颗粒大小是陆架边缘群落丰度和生物量变化的重要环境因素,阿古哈斯浅滩陆架边缘的生境异质性可能很高。
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2262529
J. Bolton, C. McQuaid
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.
阿古哈斯海洋省(AMP)沿南非南海岸大部分地区延伸,从阿古哈斯角一直到东开普省姆巴舍河口附近,拥有自己独特的暖温带海藻群,其多样性和特有性都很高。海藻群是海水温度机制的极佳指标,因此在气候变化研究中非常有用。我们提供了对该海岸 50 公里断面海水温度的新分析,并讨论了它们与上升流机制的关系,尤其侧重于阿尔戈阿湾。我们将南非南海岸/AP 海藻区系的生物地理学置于南部非洲的背景下,并讨论了其特有性模式。商业捕捞只涉及潮间带海带(Gelidium pristoides)的采集,但其他物种可能具有商业潜力。该海岸的海藻水产养殖目前仅限于作为鲍鱼饲料的岸上养殖,但讨论了海上海藻养殖的潜力,特别提到了阿尔戈阿湾和已宣布的阿尔戈阿湾水产养殖开发区。
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2276789
DN Mwaala, MR Wilhelm, S. Kirkman, J-P Roux
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.
纳米比亚的开普海狗(Arctocephalus pusillus pusillus)种群是本格拉上升流系统北部顶级掠食者生物量的主要组成部分。了解海狗的食性是理解它们在生态系统中的作用以及近期种群变化(如种群范围向北扩展)的潜在驱动因素的关键。我们利用 28 年(1994-2021 年)来每月在纳米比亚海岸的 12 个角海狗群落收集的 1413 份粪便样本中的猎物残留物,评估了它们饮食的季节性和地域性差异。我们首次比较了纳米比亚最北部地区不断壮大的海狗群落与南部海狗群落(其中许多海狗群落已经衰退)之间的饮食差异。四种鱼类在食谱中占主导地位。在本格拉北部生态系统中无处不在的胡须鰕虎鱼 Sufflogobius bibarbatus 是食物中最丰富的猎物。然而,开普海狗似乎更喜欢营养价值更高的鱼类物种开普马鲛鱼(Trachurus capensis)和灯笼鱼(Lampanyctodes hectoris),分别在北部和南部的秋季和春季转而捕食这些猎物,这与上升流期间这些物种更容易获得的情况相吻合。开普马鲛鱼的可获得性,尤其是在冬季来临前幼海豹生长和发育的关键时期,可能是纳米比亚北部海狗群落比南部海狗群落生产力更高的关键,值得进一步研究。开普竹荚鱼和开普无须鳕的幼鱼是海豹食物中唯一相对丰富的具有商业重要性的渔业物种,而历史上占主导地位的沙丁鱼比例微乎其微。
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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 Q3 Agricultural and Biological Sciences Pub Date : 2023-10-02 DOI: 10.2989/1814232X.2023.2274899
A. Whitfield, BQ Mann
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.
本综述研究了从东北部的科西河口到西南部的伯格河口等 10 个南非河口系统中依赖河口的 10 种海洋鱼类的变化状况。在所有这些系统中,所选鱼类物种的数量都在下降,但不同系统的下降原因各不相同。休闲和小规模/自给性捕捞是大多数受审查河口鱼类种群面临的共同压力,但环境退化和污染分别是圣卢西亚河口和乌姆兰加河口鱼类种群数量下降的主要原因。在已被充分研究的六个主要线鱼物种中,有两个物种被归类为过度开发种群状态,四个物种已达到崩溃水平,即每个新鱼种的产卵生物量(SBR)现在小于原始未受影响水平的 25%。此外,其中两个物种(日本褐鳕 Argyrosomus japonicus 和白薮鳕 Lithognathus lithognathus)的 SBR 值在 4-6% 之间,已被正式列入《世界自然保护联盟红色名录》(IUCN Red List)的濒危物种行列。除非采取明确措施来减少对本报告中讨论的物种的捕捞压力,并制定成功的政策来促进沿海地区健康的河口环境,否则依赖河口的鱼类种群将继续减少,这对鱼类种群以及依赖鱼类获取食物、娱乐和/或就业的人们都是不利的。
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引用次数: 0
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African Journal of Marine Science
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