African Journal of Marine Science 2021-10-06T15:42:48+00:00 Publishing Manager Open Journal Systems <p>The <em>African</em> (formerly <em>South African</em>) <em>Journal of Marine Science</em> provides an international forum for the publication of original scientific contributions or critical reviews, involving oceanic, shelf or estuarine waters, inclusive of oceanography, studies of organisms and their habitats, and aquaculture. Papers on the conservation and management of living resources, relevant social science and governance, or new techniques, are all welcomed, as are those that integrate different disciplines. Priority will be given to rigorous, question-driven research, rather than descriptive research. Contributions from African waters, including the Southern Ocean, are particularly encouraged, although not to the exclusion of those from elsewhere that have relevance to the African context. Submissions may take the form of a paper or a short communication. The journal aims to achieve a balanced representation of subject areas but also publishes proceedings of symposia in dedicated issues, as well as guest-edited suites on thematic topics in regular issues.</p><p class="MsoNormal">The <em>African Journal of Marine Science</em> is available full text online and more information can be accessed <a href="" target="_blank">here</a>. </p> The distribution of dinoflagellate cyst assemblages in recent sediments of the Oualidia Lagoon, Morocco, with a focus on toxic species 2021-10-06T13:16:02+00:00 K. Chaira H. Rhinane B. Ennaffah S. Maimouni R. Sagou S. Loulad A. BenMhamed A. Agouzouk S. BenBrahim E. Masseret M. Laabir <p>Harmful algal blooms (HABs) are becoming widely distributed and more frequent, threatening socioecosystems and human health. We determined species composition, abundance and spatial distribution of dinoflagellate cysts in the upper sediment of the Oualidia Lagoon located on the Atlantic coast of Morocco. Sediment samples were collected in 2017 at 51 stations, and environmental parameters were measured together with microphytoplankton abundance. Sediment characteristics including water percentage, organic matter content and grain size were determined. Fourteen dinoflagellate cyst morphotypes were identified, with Lingulodinium polyedrum (50%) and Gonyaulax spinifera (22%) dominating the assemblages. Total cyst densities ranged from 0 to 293 cysts g−1 dry sediment. Cyst densities were positively correlated with water content and organic matter content and increased with decreasing sediment grain size. We revealed the presence of three neurotoxic dinoflagellate species: Alexandrium minutum, the Alexandrium tamarense species complex, and Gymnodinium catenatum. Numerous cysts had accumulated in the sediment, and, because they are likely responsible for the initiation of HABs in Oualidia Lagoon, they should be monitored.</p> 2021-10-06T00:00:00+00:00 Copyright (c) Heavy metal profiles in limpets and algae on the Eastern Cape coast of South Africa 2021-10-06T13:25:44+00:00 N. Mbandzi M.D.V. Nakin G.M. Saibu A.O. Oyedeji <p>Heavy metal pollution is an increasing threat to the marine environment and is a major health concern. Both marine limpets and algae have been employed as biomonitors elsewhere in the world, but there are few or no data for these taxa along the South African coast. We investigated heavy metal concentrations in the tissues of selected limpet and algae species sampled at four sites on the southeast coast of South Africa (Silaka, Hluleka, Mthatha and Mbhashe), and determined whether there was any relationship between heavy metal concentrations in the limpets and their algae food sources as evidenced by the trophic transfer factor (TTF). Samples were collected in July 2019 and the tissues were digested following normal protocols. Heavy metals were detected using inductively coupled plasma optical emission&nbsp; spectrometry (ICP-OES). Significant differences in metal concentrations were observed among the algae species. The soft tissues of limpets from Silaka had the highest heavy metal concentrations, and samples from Mthatha had the lowest, with only mercury (Hg) occurring in high concentrations. Metal concentrations in soft tissues were generally 10-times higher than in shell tissues and differed between lower- and upper-shore species. Cadmium (Cd) biomagnified (TTF &gt; 1) in all limpet species at all sites. Cd, arsenic (As), lead (Pb) and Hg measured in our study were above the maximum limits set by the South African Department of Health. This study suggests that the use of limpet and algae species as bioindicators is feasible since they are widely distributed and can accumulate a wide range of heavy metals.</p> 2021-10-06T00:00:00+00:00 Copyright (c) A decade of surf-zone linefish monitoring in the Dwesa-Cwebe Marine Protected Area, with a preliminary assessment of the effects of rezoning and resource use 2021-10-06T13:44:12+00:00 K. Bullock A. Wood V.A. Dames J.A. Venter J. Greeff <p>An 11-year assessment of surf-zone linefish (marine fish captured on hook and line) was carried out in the Dwesa-Cwebe Marine Protected Area (MPA) in the Eastern Cape, South Africa, by research fishing to determine species and size composition, movement and relative abundance using catch per unit effort (CPUE). Comparisons were made between the Cwebe and Dwesa sections of the MPA on either side of the Mbhashe Estuary, as well as between two partially protected areas (PPAs) and two no-take zones in the Dwesa section, which came into effect in January 2016. A total of 7 241 fish representing 43 species were recorded, where 39.5% of the species are endemic, 29.5% are considered threatened by the IUCN, and 27.3% are either overexploited, collapsed or in decline. Of 3 963 tagged fish, 128 (3.2%) recaptures were recorded, of which most (62%) exhibited no movement. Localised differences in species diversity, size frequency and CPUE were detected between the Dwesa and Cwebe sections, and lower average length and CPUE of some species were recorded in the Dwesa PPAs compared with in the Dwesa no-take zones. These differences were more prominent in slow-growing, long-lived species with small home ranges, indicating the negative impacts of fishing pressure on&nbsp; vulnerable species found in this MPA and a reduction in benefits that would otherwise be associated with no-take zonation. These findings highlight the need to revisit the rezoning of the MPA with regard to the size of the no-take zones and emphasise the need&nbsp; for effective law enforcement to ensure adherence to existing regulations.</p> 2021-10-06T00:00:00+00:00 Copyright (c) Day/night patterns of habitat use by dogfish sharks (Squalidae) at photic and subphotic warm-temperate reefs: evidence for diel movements and size- and sex-segregation 2021-10-06T15:34:55+00:00 R. Juby A.T.F. Bernard A. Gӧtz <p>Dogfish sharks (genus Squalus) demonstrate complex distribution patterns that may increase their vulnerability to selective overfishing. This study investigated the day/night reef-use patterns in a population of dogfish (presumably Squalus acutipinnis) on shallow photic (13–35 m) and deep subphotic (51–99 m) nearshore rocky reefs in South Africa. Using baited remote underwater stereo-video systems, immature male dogfish were commonly recorded at subphotic deep reefs. At shallow photic reefs, dogfish were essentially absent during the day; however, a significant increase in the abundance of large male dogfish was observed at night. The size class of dogfish that moved onto photic reefs at night was not recorded at deep subphotic reefs, suggesting that they make use of a different habitat during daytime. The observed differences in depth use by cohorts of small and large male dogfish, and the absence of females on the reefs, provided strong evidence for size- and sex-segregation within the surveyed population. While the potential biotic and abiotic drivers were not directly tested, the results suggest that reef-use patterns may be linked to photic or temperature preferences and/or to competition- and mating-avoidance strategies. This new information about the use of nearshore rocky reefs by dogfish in South Africa raises important questions relating to the distribution and habitat use of females and the daytime habitats of mature males. With dogfish extensively caught in longline and trawl fisheries in South Africa, further research is needed to address the current knowledge gaps.</p> 2021-10-06T00:00:00+00:00 Copyright (c) Microplastics pollution in the sediments of creeks and estuaries of Kenya, western Indian Ocean 2021-10-06T14:18:44+00:00 J.O. Kerubo A.W.N. Muthumbi J.M. Onyari D. Robertson-Andersson E. Kimani <p>Microplastic pollution has been recognised as a global threat in marine environments and a danger to prey, predators and humans. Yet, there have been few studies in the western Indian Ocean, specifically along the Kenyan coast, which makes it difficult to estimate the extent of such pollution in the region. This is the first study on microplastics (MPs) in the sediments within creeks and estuaries (Tudor, Port Reitz and Mida creeks) on the Kenyan coast. In January/February and September 2018 sediment samples were collected for MPs analysis. The concentration of MPs differed between the sampling seasons and was distinctively higher in the second sampling season across particle sizes, suggesting that there were more MPs from larger terrestrial discharges due to increased runoff. The concentrations of total MPs, and the occurrence of different sizes, shapes and colours, were established under a microscope. The overall mean concentration was highest for the large size category of MPs (500–4 999 μm) at 9.1 (SE 0.8) particles<br>cm<sup>−2,</sup> with Tudor Creek being more polluted with MPs than Port Reitz and Mida creeks. We recommend formulation of policies on proper plastic waste management and disposal to protect nearshore ecosystems which are rich in marine biodiversity.</p> 2021-10-06T00:00:00+00:00 Copyright (c) South African marine citizen science – benefits, challenges and future directions 2021-10-06T14:32:21+00:00 W.M. Potts J.B. Mann-Lang B.Q. Mann C.L. Griffiths C.G. Attwood A.D. de Blocq S.H. Elwen R. Nel K.J. Sink R. Thornycroft <p>South Africa has a long history of engagement in citizen science (CS), particularly marine CS. This review examines the contributions made by marine CS, from the 1930s through to the current era, where websites, social media and mobile apps provide a wide range of opportunities. Largescale marine CS projects, such as the Oceanographic Research Institute’s Cooperative Fish Tagging Project, have made enormous contributions to marine scientific research. Individual citizen scientists have also made considerable contributions, particularly in taxonomy and the publication of field guides. Marine CS has also contributed towards the&nbsp; popularisation of science and improved scientific literacy through the active engagement of many citizens. These benefits align well with the visions of policies that currently guide the South African marine research agenda. However, marine CS in the developing world is not without challenges, and practitioners should be cognisant of the time and effort required to initiate and maintain viable CS initiatives. Especially, long-term successful CS projects depend on secure, ongoing funding, institutional support and enthusiastic champions. Participation by almost exclusively the urban and middle-class sectors of society is also of concern. These challenges can be addressed through stakeholder-inclusive planning, development of novel methods that engage with broader sectors of society, and regular critical evaluations of CS projects. Where global projects on the intended taxa/subject of study already exist, it may also be preferable to enter into collaborative data-sharing agreements with these to reduce operational costs and avoid duplication.</p> 2021-10-06T00:00:00+00:00 Copyright (c) Social and economic effects of marine protected areas in South Africa, with recommendations for future assessments 2021-10-06T14:44:01+00:00 J.B. Mann-Lang G.M. Branch B.Q. Mann K.J. Sink S.P. Kirkman R. Adams <p>Research on the socio-economic aspects of marine protected areas (MPAs) in South Africa is reviewed to guide evaluation and integration. After a brief international review, we used declaration notices and management plans to determine the extent to which social and economic objectives have been included in the purpose statements of MPAs. We then reviewed the current state of knowledge about the social and economic effects of South African MPAs. While many MPAs have purposes and objectives that include some social and economic objectives, these are limited in scope. Most of the MPAs that were declared before 2019 did not include objectives directly related to people or their needs. Social or economic research has been undertaken in fewer than half of the 23 coastal MPAs. Literature is largely limited to: (i) studies on negative impacts of MPAs on adjacent rural communities; (ii) selected aspects of tourism; and (iii) various aspects related to resource use. A wide range of other tangible and intangible effects, including those experienced by a broader set of stakeholders and over differing scales of time and space, have seldom been&nbsp; addressed. A case study on the Tsitsikamma MPA exemplifies challenges associated with understanding the full scope of social and economic aspects of MPAs. We conclude with recommendations to address the challenges of building a better understanding of the social and economic effects of MPAs, ensuring that these are addressed in establishing or revising objectives for each MPA, and assessing the extent to which the objectives meet both human and environmental needs.</p> 2021-10-06T00:00:00+00:00 Copyright (c) Evaluating the evidence for ecological effectiveness of South Africa’s marine protected areas 2021-10-06T15:03:30+00:00 S.P. Kirkman B.Q. Mann K.J. Sink R. Adams T-C. Livingstone J.B. Mann-Lang M.C. Pfaff T. Samaai M.G. van der Bank L. Williams G.M. Branch <p>We reviewed 140 papers to assess the ecological effectiveness of South Africa’s marine protected areas (MPAs). Evidence was assessed for coverage and representivity, protection of important biodiversity areas, other recognised elements of effectiveness, connectivity, and ecological effects—from the scale of individual MPAs to the MPA network scale. We conducted complementary novel analyses to supplement the review and to objectively determine where and how the MPA network can be improved. Evidence shows that South Africa’s MPAs now provide some protection to all ecoregions and 87% of ecosystem types but to less than 50% of assessed species groups. MPAs are generally well-sited, but gaps were revealed on the west coast and in estuaries, the deep sea, and two ecologically and biologically significant areas. Enforcement emerged as a key concern, and many MPAs could be improved through expansion or by increasing no-take areas. The majority of relevant papers recorded beneficial ecological effects, detectable as increases in parameters such as the abundance, biomass, sizes or reproductive output of species. Few papers examined whether ecological benefits translate into adjacent fisheries benefits, but all those that did recorded positive effects. Full protection was more effective than partial protection, with effectiveness most clearly demonstrated for vulnerable target taxa. Further research and&nbsp; monitoring to achieve evaluations of effectiveness are recommended, with greater focus on neglected MPAs and species.&nbsp; Understanding the ecological connectivity between MPAs, an important dimension for climate-change adaptation and hence for the persistence and resilience of South Africa’s marine biodiversity, is identified as a key area for future research and inclusion in MPA planning.</p> 2021-10-06T00:00:00+00:00 Copyright (c) The first report of Naobranchia cygniformis Hesse, 1863 (Copepoda: Lernaeopodidae) off South Africa, with a redescription of the adult female 2021-10-06T15:15:09+00:00 S.M. Dippenaar M.M. Sebone <p><em>Naobranchia cygniformi</em>s Hesse, 1863 is one of 21 accepted species of the genus Naobranchia, which is distinguished from other&nbsp; genera in the family Lernaeopodidae by the possession of ribbon-like maxillae. The original description of <em>N. cygniformis</em> lacked detail concerning the armature, and later reports have not included a redescription. Thus, a redescription with details regarding the armature will be valuable for future comparative purposes. Additionally, this report of this parasitic copepod on the seabream Pagellus natalensis from the east coast of South Africa constitutes a new host and geographic record, since the only other <em>Naobranchia</em> species reported from the Indian Ocean off South Africa are<em> N. kabatana </em>and<em> N. pritchardae.</em></p> 2021-10-06T00:00:00+00:00 Copyright (c) Bull shark Carcharhinus leucas recruitment into the St Lucia Estuary, South Africa, after prolonged mouth closure, and the first observation of a neonate bull shark preyed on by a Nile crocodile <i>Crocodylus niloticus</i> 2021-10-06T15:39:01+00:00 R. Daly P. Le Noury T.N. Hempson M. Ziembicki J.M. Olbers G.M. Brokensha B.Q. Mann <p>Estuaries provide critical nursery habitat for juvenile bull sharks <em>Carcharhinus leucas</em>, as they have the ability to withstand a wide&nbsp; range of salinities. St Lucia is the largest estuarine lake in Africa and was once a key nursery for bull sharks until a prolonged and near-continuous period of mouth closure and drought between 2002 and 2021. The estuary mouth was opened for the first time in 13 years on 6 January 2021, and, within 10 days, bull shark pups recruited into the estuary. On 16 January, an adult Nile crocodile Crocodylus niloticus was observed preying on a live neonate bull shark which it swallowed whole. This observation provided the first photographic evidence in Africa and highlighted a unique interaction between these species, which are top predators in the&nbsp; freshwater and coastal environments, respectively. Estuaries remain important nursery habitats for bull sharks in the region and we assembled the known records of bull shark occurrence in all South African estuaries. In summary, the rapid recruitment of bull shark pups into St Lucia Estuary is notable for the management and conservation implications for this important estuarine system, as well as for regional bull shark populations.</p> 2021-10-06T00:00:00+00:00 Copyright (c)