Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1960890
W. Potts, J. Mann-Lang, B. Mann, C. Griffiths, C. Attwood, AD de Blocq, S. Elwen, R. Nel, K. Sink, R. Thornycroft
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 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.
{"title":"South African marine citizen science – benefits, challenges and future directions","authors":"W. Potts, J. Mann-Lang, B. Mann, C. Griffiths, C. Attwood, AD de Blocq, S. Elwen, R. Nel, K. Sink, R. Thornycroft","doi":"10.2989/1814232X.2021.1960890","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1960890","url":null,"abstract":"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 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"353 - 366"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47930097","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}
Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1951353
K. Bullock, A. Wood, V. Dames, J. Venter, J. Greeff
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 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 for effective law enforcement to ensure adherence to existing regulations.
{"title":"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","authors":"K. Bullock, A. Wood, V. Dames, J. Venter, J. Greeff","doi":"10.2989/1814232X.2021.1951353","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1951353","url":null,"abstract":"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 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 for effective law enforcement to ensure adherence to existing regulations.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"309 - 323"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48599346","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}
Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1966505
Joyce O. Kerubo, A. Muthumbi, JM Onyari, D. Robertson-Andersson, E. Kimani
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 cm−2, 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.
{"title":"Microplastics pollution in the sediments of creeks and estuaries of Kenya, western Indian Ocean","authors":"Joyce O. Kerubo, A. Muthumbi, JM Onyari, D. Robertson-Andersson, E. Kimani","doi":"10.2989/1814232X.2021.1966505","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1966505","url":null,"abstract":"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 cm−2, 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"337 - 352"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41977481","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}
Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1945684
K. Chaira, H. Rhinane, B. Ennaffah, S. Maimouni, R. Sagou, S. Loulad, A. BenMhamed, A. Agouzouk, S. Benbrahim, E. Masseret, M. Laabir
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.
{"title":"The distribution of dinoflagellate cyst assemblages in recent sediments of the Oualidia Lagoon, Morocco, with a focus on toxic species","authors":"K. Chaira, H. Rhinane, B. Ennaffah, S. Maimouni, R. Sagou, S. Loulad, A. BenMhamed, A. Agouzouk, S. Benbrahim, E. Masseret, M. Laabir","doi":"10.2989/1814232X.2021.1945684","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1945684","url":null,"abstract":"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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"279 - 292"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44643890","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}
Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1946425
SM Dippenaar, MM Sebone
Naobranchia cygniformis Hesse, 1863 is one of 21 accepted species of the genus Naobranchia, which is distinguished from other genera in the family Lernaeopodidae by the possession of ribbon-like maxillae. The original description of N. cygniformis 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 Naobranchia species reported from the Indian Ocean off South Africa are N. kabatana and N. pritchardae.
{"title":"The first report of Naobranchia cygniformis Hesse, 1863 (Copepoda: Lernaeopodidae) off South Africa, with a redescription of the adult female","authors":"SM Dippenaar, MM Sebone","doi":"10.2989/1814232X.2021.1946425","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1946425","url":null,"abstract":"Naobranchia cygniformis Hesse, 1863 is one of 21 accepted species of the genus Naobranchia, which is distinguished from other genera in the family Lernaeopodidae by the possession of ribbon-like maxillae. The original description of N. cygniformis 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 Naobranchia species reported from the Indian Ocean off South Africa are N. kabatana and N. pritchardae.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"413 - 416"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42183398","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}
Pub Date : 2021-07-03DOI: 10.2989/1814232X.2021.1964599
R. Daly, P. Le Noury, TN Hempson, M. Ziembicki, J. Olbers, GM Brokensha, B. Mann
Estuaries provide critical nursery habitat for juvenile bull sharks Carcharhinus leucas, as they have the ability to withstand a wide 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 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.
{"title":"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 Crocodylus niloticus","authors":"R. Daly, P. Le Noury, TN Hempson, M. Ziembicki, J. Olbers, GM Brokensha, B. Mann","doi":"10.2989/1814232X.2021.1964599","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1964599","url":null,"abstract":"Estuaries provide critical nursery habitat for juvenile bull sharks Carcharhinus leucas, as they have the ability to withstand a wide 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 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"417 - 421"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42895350","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}
Pub Date : 2021-04-03DOI: 10.2989/1814232X.2021.1901248
FE Dakwa, P. Ryan, B. Dyer, R. Crawford, P. Pistorius, A. Makhado
Populations of the macaroni penguin Eudyptes chrysolophus and the eastern rockhopper penguin E. filholi breeding at Marion Island (Prince Edward Islands) in the sub-Antarctic Indian Ocean decreased from 1994 to 2018. We examined their diets when rearing chicks during this period. There was substantial overlap in the diets of the two species, with crustaceans, dominated by the euphausiids Thysanoessa vicina and Euphausia vallentini, making up >80% of the diets by number and >60% by mass over the study period. The lanternfishes Krefftichthys anderssoni and Protomyctophum tenisoni were the most-commonly consumed fish in the diet of breeding macaroni penguins and dominated in their diet in three of the 25 years (1994, 1998 and 2014); they were also the most commonly consumed fish by eastern rockhopper penguins. Macaroni penguins consumed more of the amphipod crustacean Themisto gaudichaudii and the lanternfish Electrona carlsbergi as well as a greater diversity of and larger-sized fish than did eastern rockhopper penguins. The horsefish Zanclorhynchus spinifer was found in substantial amounts in the diet of eastern rockhopper penguins in 1996 and 1997. Despite annual variations in relative prey contributions to the diets, there were no significant long-term changes in the diet of either penguin species over the study period or when compared with an earlier assessment in 1982. We conclude that changes in the relative proportions of prey in the diets of these penguin species during breeding are unlikely to account for the recent declines in these penguin populations.
{"title":"Long-term variation in the breeding diets of macaroni and eastern rockhopper penguins at Marion Island (1994–2018)","authors":"FE Dakwa, P. Ryan, B. Dyer, R. Crawford, P. Pistorius, A. Makhado","doi":"10.2989/1814232X.2021.1901248","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1901248","url":null,"abstract":"Populations of the macaroni penguin Eudyptes chrysolophus and the eastern rockhopper penguin E. filholi breeding at Marion Island (Prince Edward Islands) in the sub-Antarctic Indian Ocean decreased from 1994 to 2018. We examined their diets when rearing chicks during this period. There was substantial overlap in the diets of the two species, with crustaceans, dominated by the euphausiids Thysanoessa vicina and Euphausia vallentini, making up >80% of the diets by number and >60% by mass over the study period. The lanternfishes Krefftichthys anderssoni and Protomyctophum tenisoni were the most-commonly consumed fish in the diet of breeding macaroni penguins and dominated in their diet in three of the 25 years (1994, 1998 and 2014); they were also the most commonly consumed fish by eastern rockhopper penguins. Macaroni penguins consumed more of the amphipod crustacean Themisto gaudichaudii and the lanternfish Electrona carlsbergi as well as a greater diversity of and larger-sized fish than did eastern rockhopper penguins. The horsefish Zanclorhynchus spinifer was found in substantial amounts in the diet of eastern rockhopper penguins in 1996 and 1997. Despite annual variations in relative prey contributions to the diets, there were no significant long-term changes in the diet of either penguin species over the study period or when compared with an earlier assessment in 1982. We conclude that changes in the relative proportions of prey in the diets of these penguin species during breeding are unlikely to account for the recent declines in these penguin populations.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"187 - 199"},"PeriodicalIF":1.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45332358","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}
Pub Date : 2021-04-03DOI: 10.2989/1814232X.2021.1925346
A. Dinoi, M. Rius, M. Tine, P. Teske
The development of new genetic resources is key for biological conservation in an era when the preservation of biodiversity is crucial. Here, we report the development of microsatellites and mitochondrial markers for the redbait species Pyura herdmani and P. stolonifera, both important bioengineers along African coastlines. Specifically, we identified microsatellites by means of pyrosequencing and variable regions in the mitochondrial genome using RAD-seq libraries that were generated with Illumina sequencing. A total of 4 339 putative microsatellites were found, of which 32 were tested on individuals collected along the southeast coast of South Africa. Of those, five microsatellites cross-amplified consistently in both species, and these were tested on a total of 260 samples. Additionally, we mapped the partial mitochondrial genome of a small number of individuals from both species and identified the most-variable regions by comparing a small number of individuals from all regions where these species have been recorded (including western South Africa and northwest Africa). The genetic markers developed here can be used to conduct population genetic studies, to monitor range shifts under contemporary climate change, and to help in preserving ecosystem functioning along African coastlines.
{"title":"Development of genetic tools for the redbait species Pyura herdmani and P. stolonifera, important bioengineers along African coastlines","authors":"A. Dinoi, M. Rius, M. Tine, P. Teske","doi":"10.2989/1814232X.2021.1925346","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1925346","url":null,"abstract":"The development of new genetic resources is key for biological conservation in an era when the preservation of biodiversity is crucial. Here, we report the development of microsatellites and mitochondrial markers for the redbait species Pyura herdmani and P. stolonifera, both important bioengineers along African coastlines. Specifically, we identified microsatellites by means of pyrosequencing and variable regions in the mitochondrial genome using RAD-seq libraries that were generated with Illumina sequencing. A total of 4 339 putative microsatellites were found, of which 32 were tested on individuals collected along the southeast coast of South Africa. Of those, five microsatellites cross-amplified consistently in both species, and these were tested on a total of 260 samples. Additionally, we mapped the partial mitochondrial genome of a small number of individuals from both species and identified the most-variable regions by comparing a small number of individuals from all regions where these species have been recorded (including western South Africa and northwest Africa). The genetic markers developed here can be used to conduct population genetic studies, to monitor range shifts under contemporary climate change, and to help in preserving ecosystem functioning along African coastlines.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"251 - 257"},"PeriodicalIF":1.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44921821","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}
Pub Date : 2021-04-03DOI: 10.2989/1814232X.2021.1916591
M. Lipiński, MA Mmethi, D. Yemane, J. Githaiga-Mwicigi, W. Sauer
Temporal trends in the size composition (length frequency) and length–weight (L–W) relationship of chokka squid Loligo reynaudii on the south coast of South Africa were assessed over periods spanning 22 years: length frequencies from 1996 to 2017 (with 15 years represented); and L–W relationships over 9 years between 1994 and 2016. To allow for comparison, identical data selection and processing was adopted for all years considered (i.e. identical period of 60 days in spring–summer; the same depths and areas; chokka with empty stomachs; and squid of the same maturity stage). Although there were no significant long-term temporal trends in the mean lengths, there was a significant short-term drop in the mean lengths over the years 2014–2017 (especially in females), which could not be attributed with certainty to any cause. A tentative explanation is that this drop might be linked to the introduction of an additional closed season in these years. The estimated parameters of the L–W relationship also revealed no trend over the years considered. Investigation of the caecum colour, which indicates the state of starvation (white: 8 h on average after food ingestion; yellow: 6 to 7 h after food ingestion), showed significantly more starving males than starving females. Starvation of males on the spawning grounds might be associated with the spawning behaviour of chokka.
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Pub Date : 2021-04-03DOI: 10.2989/1814232X.2021.1897039
M. Nunes, D. Lemley, G. Matcher, J. Adams
The occurrence of harmful algal blooms (HABs) is increasing in frequency and intensity in South African estuaries because of eutrophication. This study used DNA metabarcoding to identify the benthic diatom community structure in the eutrophic Sundays Estuary. The recurrent HAB phytoplankton species Heterosigma akashiwo was recorded at bloom concentrations (∼100 µg Chl a l−1) in the brackish, vertically stratified middle reaches of the estuary. In contrast, microphytobenthos biomass increased towards the upper reaches in response to elevated availability of total oxidised nitrogen (NOx) and increased sediment stability. A total of 76 diatom species were identified using the molecular technique. Seven known nutrient-tolerant diatom species indicate a preference for either ammonium or NOx enrichment. Benthic diatom community diversity (H′ < 1) and evenness (J′ < 0.25) were low in the brackish middle reaches of the estuary, where the HABs decreased available light. Heterosigma akashiwo has been found in previous studies to suppress the growth of co-occurring taxa. Future research efforts should focus on verifying this relationship over seasonal timescales given the dominance of H. akashiwo in spring/summer. As the persistently nutrient-enriched state and stable flow conditions of the Sundays Estuary is the key driver of change, management efforts should be geared towards re-establishing the estuary’s natural flow variations and to measures that can mitigate nutrient pollution.
由于富营养化，南非河口有害藻华的发生频率和强度都在增加。本研究利用DNA代谢编码技术对富营养化Sundays河口的底栖硅藻群落结构进行了鉴定。在河口半咸水、垂直分层的中游地区，记录到赤潮浓度为（～100µg Chl a l−1）的赤潮浮游植物物种Heterosigma akashiwo。相比之下，由于总氧化氮（NOx）的可用性提高和沉积物稳定性增加，向上游方向的微型底栖生物生物生物量增加。利用分子技术共鉴定出76种硅藻。七种已知的耐营养硅藻物种表明它们更喜欢富集铵或NOx。河口半咸水中游底栖硅藻群落多样性（H′<1）和均匀度（J′<0.025）较低，赤潮降低了可用光。在以前的研究中已经发现赤尾异西格玛可以抑制共存类群的生长。鉴于H.akashiwo在春季/夏季占主导地位，未来的研究工作应侧重于在季节性时间尺度上验证这种关系。由于Sundays河口持续的营养丰富状态和稳定的水流条件是变化的关键驱动力，管理工作应致力于重建河口的自然流量变化，并采取措施减轻营养污染。
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