Pub Date : 2021-10-02DOI: 10.2989/1814232X.2021.1982769
C. Pierpoint, E. Oliver, L. Scala, D. Hedgeland
The first records of beaked whales, including Cuvier’s beaked whale Ziphius cavirostris, are reported from an acoustic baseline survey in the territorial waters of the Democratic Republic of São Tomé and Príncipe, Gulf of Guinea, West Africa. The survey was carried out between late 2018 and early 2019 using an AutoNaut unmanned surface vessel (USV), which is propelled by the motion of waves and operated remotely via a satellite link. The USV towed a hydrophone array on a cable, and over the course of 75 days the USV completed 1 772 km of acoustic survey effort. Beaked whale encounters were not uncommon and occurred on 28 of the 75 survey days. They were widespread on the shelf edge and in oceanic habitats above the abyssal plain. The average water depth at which acoustic detections were recorded was 2 519 (SD 555) m (n = 43). Beaked whales were evenly distributed across areas with different seabed characteristics: the number of encounters recorded in areas characterised by seabed gradient and ruggedness did not differ from that expected after accounting for survey effort. The majority of acoustic detections were attributable to Cuvier’s beaked whales, based on spectral and temporal characteristics of click-train vocalisations. The results provide baseline information on the distribution of beaked whales and suggest that passive acoustic methods using a small USV are well-suited to surveys of this species group, possibly because beaked whales, which are sensitive to disturbance associated with underwater sound sources, are less likely to avoid small, quiet vessels than larger vessels.
第一批喙鲸的记录，包括居维叶喙鲸Ziphius cavirostris，是在西非几内亚湾的东民主共和国和Príncipe的领海进行的声学基线调查中报告的。该调查是在2018年底至2019年初期间使用AutoNaut无人水面船(USV)进行的，该船由波浪运动推动，通过卫星链路远程操作。USV用缆绳拖曳水听器阵列，在75天的过程中，USV完成了1772公里的声学调查工作。喙鲸的遭遇并不罕见，在75天的调查中有28天发生了。它们广泛分布于陆架边缘和深海平原之上的海洋栖息地。记录声波探测的平均水深为2 519 (SD 555) m (n = 43)。喙鲸均匀分布在具有不同海底特征的区域:在以海底梯度和崎岖为特征的区域记录的遭遇数量与考虑调查努力后的预期数量没有差异。根据咔嗒声的频谱和时间特征，大多数的声学探测可归因于居维叶喙鲸。研究结果提供了喙鲸分布的基线信息，并表明使用小型USV的被动声学方法非常适合对这一物种群体进行调查，可能是因为喙鲸对水下声源的干扰很敏感，与大型船只相比，它们不太可能避开小而安静的船只。
{"title":"An acoustic survey of beaked whale distribution at São Tomé and Príncipe, Gulf of Guinea, using an unmanned surface vessel","authors":"C. Pierpoint, E. Oliver, L. Scala, D. Hedgeland","doi":"10.2989/1814232X.2021.1982769","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1982769","url":null,"abstract":"The first records of beaked whales, including Cuvier’s beaked whale Ziphius cavirostris, are reported from an acoustic baseline survey in the territorial waters of the Democratic Republic of São Tomé and Príncipe, Gulf of Guinea, West Africa. The survey was carried out between late 2018 and early 2019 using an AutoNaut unmanned surface vessel (USV), which is propelled by the motion of waves and operated remotely via a satellite link. The USV towed a hydrophone array on a cable, and over the course of 75 days the USV completed 1 772 km of acoustic survey effort. Beaked whale encounters were not uncommon and occurred on 28 of the 75 survey days. They were widespread on the shelf edge and in oceanic habitats above the abyssal plain. The average water depth at which acoustic detections were recorded was 2 519 (SD 555) m (n = 43). Beaked whales were evenly distributed across areas with different seabed characteristics: the number of encounters recorded in areas characterised by seabed gradient and ruggedness did not differ from that expected after accounting for survey effort. The majority of acoustic detections were attributable to Cuvier’s beaked whales, based on spectral and temporal characteristics of click-train vocalisations. The results provide baseline information on the distribution of beaked whales and suggest that passive acoustic methods using a small USV are well-suited to surveys of this species group, possibly because beaked whales, which are sensitive to disturbance associated with underwater sound sources, are less likely to avoid small, quiet vessels than larger vessels.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"443 - 454"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46040149","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 : 2021-10-02DOI: 10.2989/1814232X.2021.1989487
B. Ohowa, L. Kiteresi, V. Wanjeri, SM Mwamburi, SL Tunje
The potential of the marine leaf sponge Phyllospongia foliascens as a simple biomonitor of trace element pollution was assessed. The concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn) and zinc (Zn) in sediments and in P. foliascens from four sites of varying anthropogenic impacts along the Kenyan coast were determined. The concentrations of all elements, other than Mn, were higher in P. foliascens relative to the sediment at Mkomani Beach, the most polluted site, and the concentrations of As and Cd were higher in P. foliascens than in sediments at all sites. The concentration ratio C P. foliascens /Csed, representing the extent of accumulation of the elements in the sponge relative to the sediment, ranged between 1.25 and 9.43 for all the elements except for Mn at Mkomani Beach, and between 1.26 and 13.30 for As and Cd at all the sites. The results suggest that P. foliascens could be a suitable biomonitor of As and Cd. Further studies are recommended to identify suitable biomonitors of a variety of pollutant elements that could inform policy decisions geared towards novel and efficient options for managing trace element pollution in Kenya’s coastal and marine environment.
{"title":"Sponges as simple biomonitoring tools for trace element pollution in marine environments: insights from a Kenyan study focused on the leaf sponge Phyllospongia foliascens","authors":"B. Ohowa, L. Kiteresi, V. Wanjeri, SM Mwamburi, SL Tunje","doi":"10.2989/1814232X.2021.1989487","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1989487","url":null,"abstract":"The potential of the marine leaf sponge Phyllospongia foliascens as a simple biomonitor of trace element pollution was assessed. The concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn) and zinc (Zn) in sediments and in P. foliascens from four sites of varying anthropogenic impacts along the Kenyan coast were determined. The concentrations of all elements, other than Mn, were higher in P. foliascens relative to the sediment at Mkomani Beach, the most polluted site, and the concentrations of As and Cd were higher in P. foliascens than in sediments at all sites. The concentration ratio C P. foliascens /Csed, representing the extent of accumulation of the elements in the sponge relative to the sediment, ranged between 1.25 and 9.43 for all the elements except for Mn at Mkomani Beach, and between 1.26 and 13.30 for As and Cd at all the sites. The results suggest that P. foliascens could be a suitable biomonitor of As and Cd. Further studies are recommended to identify suitable biomonitors of a variety of pollutant elements that could inform policy decisions geared towards novel and efficient options for managing trace element pollution in Kenya’s coastal and marine environment.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"533 - 538"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44561116","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 : 2021-10-02DOI: 10.2989/1814232X.2021.1987984
G. Passuni, L. Human, SN Riddick, P. Pattrick, M. Bizani, S. Deyzel, N. Strydom, T. Bornman, L. Pichegru
In coastal waters, nutrient supplies originate principally from allochthonous sources, such as inputs from rivers, estuaries or oceanic waters. Recently, it has been suggested that marine life contributes to the nutrient load, with penguin colonies being the largest contributor worldwide. This study aimed to quantify the nitrogen (N) and phosphorus (P) produced by the largest colony of African penguins Spheniscus demersus, which is located in South Africa, using a bioenergetics model (GUANO). We modelled the fate of N excreted and measured potential effects on the physicochemical parameters of the waters surrounding St Croix Island, Algoa Bay, as well as on local primary and secondary productivity. A total of 58.66 (SD 14.99) tonnes (t) of N and 4.35 (SD 1.20) t of P were estimated to be produced by penguins annually, a magnitude comparable to that exported by permanently open estuaries in Algoa Bay. However, only 8% of penguin-produced N washed into the ocean (after moderate to heavy precipitation) as total ammoniacal N, while 58% of N was excreted as volatilised ammonia. Consequently, penguin excreta appeared to have limited influence on productivity in the waters surrounding St Croix Island, at both proximate (200 m) and distant (2 km) locations. Additional experiments should confirm whether the input of N excretion in coastal waters was too ephemeral to be detected at the monthly scale, or whether the effects were restricted to intertidal communities. Regardless, sources of nutrients other than penguins, such as coastal upwelling and runoff, are likely to have a greater influence on the physicochemical dynamics and productivity of Algoa Bay nearshore waters.
{"title":"Is the largest African penguin colony in South Africa influencing local ocean productivity?","authors":"G. Passuni, L. Human, SN Riddick, P. Pattrick, M. Bizani, S. Deyzel, N. Strydom, T. Bornman, L. Pichegru","doi":"10.2989/1814232X.2021.1987984","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1987984","url":null,"abstract":"In coastal waters, nutrient supplies originate principally from allochthonous sources, such as inputs from rivers, estuaries or oceanic waters. Recently, it has been suggested that marine life contributes to the nutrient load, with penguin colonies being the largest contributor worldwide. This study aimed to quantify the nitrogen (N) and phosphorus (P) produced by the largest colony of African penguins Spheniscus demersus, which is located in South Africa, using a bioenergetics model (GUANO). We modelled the fate of N excreted and measured potential effects on the physicochemical parameters of the waters surrounding St Croix Island, Algoa Bay, as well as on local primary and secondary productivity. A total of 58.66 (SD 14.99) tonnes (t) of N and 4.35 (SD 1.20) t of P were estimated to be produced by penguins annually, a magnitude comparable to that exported by permanently open estuaries in Algoa Bay. However, only 8% of penguin-produced N washed into the ocean (after moderate to heavy precipitation) as total ammoniacal N, while 58% of N was excreted as volatilised ammonia. Consequently, penguin excreta appeared to have limited influence on productivity in the waters surrounding St Croix Island, at both proximate (200 m) and distant (2 km) locations. Additional experiments should confirm whether the input of N excretion in coastal waters was too ephemeral to be detected at the monthly scale, or whether the effects were restricted to intertidal communities. Regardless, sources of nutrients other than penguins, such as coastal upwelling and runoff, are likely to have a greater influence on the physicochemical dynamics and productivity of Algoa Bay nearshore waters.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"455 - 469"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48328143","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 : 2021-10-02DOI: 10.2989/1814232X.2021.1997814
B. O'connor, N. Cullain
Persistent threats from fishing pressure and increasing habitat degradation, as well as slow recovery rates resulting from K-selected life histories, are putting increasing numbers of elasmobranch species (sharks, rays and skates) at risk of extinction worldwide. Global declines in elasmobranch populations merit evidence-based conservation measures, but establishment of such measures has been hindered by a paucity of population-level data. Mozambique supports a high number of threatened (Vulnerable, Endangered or Critically Endangered) and Data Deficient elasmobranch species; however, most of these populations are poorly understood. We collected baseline data on the presence, species richness, diversity, and habitat use of elasmobranchs within Zavora Bay, Mozambique, using baited remote underwater video and underwater visual census surveys, at six sites, from January 2017 to March 2020. Our results show that Zavora Bay is used year-round by 20 elasmobranch species, all of which are listed on the IUCN Red List of Threatened Species as either Data Deficient, threatened, or Near Threatened with declining population trends. Many of these species are heavily targeted by fisheries or caught as bycatch throughout their range, and some do not encounter protected areas anywhere within their natural range, highlighting the urgency to establish adequate conservation strategies to prevent further population declines.
{"title":"Distribution and community structure of at-risk and Data Deficient elasmobranchs in Zavora Bay, Mozambique","authors":"B. O'connor, N. Cullain","doi":"10.2989/1814232X.2021.1997814","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1997814","url":null,"abstract":"Persistent threats from fishing pressure and increasing habitat degradation, as well as slow recovery rates resulting from K-selected life histories, are putting increasing numbers of elasmobranch species (sharks, rays and skates) at risk of extinction worldwide. Global declines in elasmobranch populations merit evidence-based conservation measures, but establishment of such measures has been hindered by a paucity of population-level data. Mozambique supports a high number of threatened (Vulnerable, Endangered or Critically Endangered) and Data Deficient elasmobranch species; however, most of these populations are poorly understood. We collected baseline data on the presence, species richness, diversity, and habitat use of elasmobranchs within Zavora Bay, Mozambique, using baited remote underwater video and underwater visual census surveys, at six sites, from January 2017 to March 2020. Our results show that Zavora Bay is used year-round by 20 elasmobranch species, all of which are listed on the IUCN Red List of Threatened Species as either Data Deficient, threatened, or Near Threatened with declining population trends. Many of these species are heavily targeted by fisheries or caught as bycatch throughout their range, and some do not encounter protected areas anywhere within their natural range, highlighting the urgency to establish adequate conservation strategies to prevent further population declines.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"521 - 532"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44393303","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 : 2021-10-02DOI: 10.2989/1814232X.2021.1987985
F. El Asri, A. Errhif, MN Tamsouri, H. Nhhala, M. Maanan, H. Zidane
The molluscan assemblages inhabiting the coastal waters of Oualidia Lagoon, Morocco, were studied during winter and summer of 2013. The taxonomic composition and diversity were determined at 43 sample sites. Thirty-four mollusc taxa were recorded in total, including 12 species of bivalves, 20 species of gastropods, 1 species of polyplacophoran and 1 species of cephalopod. Twenty-six of these species are reported here for the first time in Oualidia Lagoon. The gastropod Peringia ulvae and the bivalve Abra alba were the most abundant taxa in both seasons. The deposit-feeder trophic group was highly dominant in both seasons. A classification analysis revealed the existence of three main clusters from downstream to upstream in both seasons: a marine assemblage, a transition assemblage and a lagoon assemblage. Canonical correspondence analyses indicated that the main environmental variables governing the spatial distribution of the molluscs in winter are salinity, temperature and granulometry, whereas in summer they are salinity and granulometry. This study provides a good baseline for future ecological research.
{"title":"Temporal and spatial variation of the molluscan community structure in Oualidia Lagoon, Moroccan Atlantic coast","authors":"F. El Asri, A. Errhif, MN Tamsouri, H. Nhhala, M. Maanan, H. Zidane","doi":"10.2989/1814232X.2021.1987985","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1987985","url":null,"abstract":"The molluscan assemblages inhabiting the coastal waters of Oualidia Lagoon, Morocco, were studied during winter and summer of 2013. The taxonomic composition and diversity were determined at 43 sample sites. Thirty-four mollusc taxa were recorded in total, including 12 species of bivalves, 20 species of gastropods, 1 species of polyplacophoran and 1 species of cephalopod. Twenty-six of these species are reported here for the first time in Oualidia Lagoon. The gastropod Peringia ulvae and the bivalve Abra alba were the most abundant taxa in both seasons. The deposit-feeder trophic group was highly dominant in both seasons. A classification analysis revealed the existence of three main clusters from downstream to upstream in both seasons: a marine assemblage, a transition assemblage and a lagoon assemblage. Canonical correspondence analyses indicated that the main environmental variables governing the spatial distribution of the molluscs in winter are salinity, temperature and granulometry, whereas in summer they are salinity and granulometry. This study provides a good baseline for future ecological research.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"471 - 481"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49598613","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 : 2021-10-02DOI: 10.2989/1814232X.2021.1996459
Tamaryn A. Asbury, R. Bennett, Ashley A. G. Price, C. da Silva, M. Bürgener, JD Klein, SN Maduna, N. Sidat, S. Fernando, A. Bester-van der Merwe
In recent decades, a combination of increasing demand and economic globalisation has created a global market for elasmobranch products, especially the highly prized shark fins for Asian markets. Morphological species identification, as well as traditional cytochrome c oxidase subunit I (COI) barcoding of shark fins and other products, become challenging when in a processed state (such as dried or bleached shark fins). Here a mini-barcoding multiplex assay was applied to determine the species of origin in case studies from southern Africa involving confiscated shark fins in different states of processing. This highlights that the illegal shark fin trade in southern Africa to a large extent comprises threatened species. Matching of sequences of the confiscated fins against public databases revealed several threatened species, including the CITES-listed species Carcharodon carcharias, Carcharhinus longimanus, Isurus oxyrinchus, Rhynchobatus djiddensis and Sphyrna lewini. The findings highlight the need for improved trade monitoring, such as to eliminate illegal trade in shark fins, which can in part be achieved through more widespread genetic sampling of internationally traded products. However, a major limitation to DNA barcoding in general lies in the lack of curated voucher specimens available on public databases. To facilitate the application of molecular methods in a more comprehensive evaluation of elasmobranch trade regionally, a concerted effort to create reliable curated sequence data is recommended.
{"title":"Application of DNA mini-barcoding reveals illegal trade in endangered shark products in southern Africa","authors":"Tamaryn A. Asbury, R. Bennett, Ashley A. G. Price, C. da Silva, M. Bürgener, JD Klein, SN Maduna, N. Sidat, S. Fernando, A. Bester-van der Merwe","doi":"10.2989/1814232X.2021.1996459","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1996459","url":null,"abstract":"In recent decades, a combination of increasing demand and economic globalisation has created a global market for elasmobranch products, especially the highly prized shark fins for Asian markets. Morphological species identification, as well as traditional cytochrome c oxidase subunit I (COI) barcoding of shark fins and other products, become challenging when in a processed state (such as dried or bleached shark fins). Here a mini-barcoding multiplex assay was applied to determine the species of origin in case studies from southern Africa involving confiscated shark fins in different states of processing. This highlights that the illegal shark fin trade in southern Africa to a large extent comprises threatened species. Matching of sequences of the confiscated fins against public databases revealed several threatened species, including the CITES-listed species Carcharodon carcharias, Carcharhinus longimanus, Isurus oxyrinchus, Rhynchobatus djiddensis and Sphyrna lewini. The findings highlight the need for improved trade monitoring, such as to eliminate illegal trade in shark fins, which can in part be achieved through more widespread genetic sampling of internationally traded products. However, a major limitation to DNA barcoding in general lies in the lack of curated voucher specimens available on public databases. To facilitate the application of molecular methods in a more comprehensive evaluation of elasmobranch trade regionally, a concerted effort to create reliable curated sequence data is recommended.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"511 - 520"},"PeriodicalIF":1.2,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49027094","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.2021.1948918
N. Mbandzi, M.D.V. Nakin, Gm Saibu, A. Oyedeji
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 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 > 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.
{"title":"Heavy metal profiles in limpets and algae on the Eastern Cape coast of South Africa","authors":"N. Mbandzi, M.D.V. Nakin, Gm Saibu, A. Oyedeji","doi":"10.2989/1814232X.2021.1948918","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1948918","url":null,"abstract":"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 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 > 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"293 - 308"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48965143","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.2021.1951839
R. Juby, A. Bernard, A. Götz
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.
{"title":"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","authors":"R. Juby, A. Bernard, A. Götz","doi":"10.2989/1814232X.2021.1951839","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1951839","url":null,"abstract":"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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"325 - 336"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47360969","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.2021.1962975
S. Kirkman, B. Mann, K. Sink, R. Adams, Tamsyn-Claire Livingstone, J. Mann-Lang, M. Pfaff, T. Samaai, MG van der Bank, L. Williams, GM Branch
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 monitoring to achieve evaluations of effectiveness are recommended, with greater focus on neglected MPAs and species. 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.
{"title":"Evaluating the evidence for ecological effectiveness of South Africa’s marine protected areas","authors":"S. Kirkman, B. Mann, K. Sink, R. Adams, Tamsyn-Claire Livingstone, J. Mann-Lang, M. Pfaff, T. Samaai, MG van der Bank, L. Williams, GM Branch","doi":"10.2989/1814232X.2021.1962975","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1962975","url":null,"abstract":"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 monitoring to achieve evaluations of effectiveness are recommended, with greater focus on neglected MPAs and species. 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"389 - 412"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46053687","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.2021.1961166
J. Mann-Lang, GM Branch, B. Mann, K. Sink, S. Kirkman, R. Adams
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 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.
{"title":"Social and economic effects of marine protected areas in South Africa, with recommendations for future assessments","authors":"J. Mann-Lang, GM Branch, B. Mann, K. Sink, S. Kirkman, R. Adams","doi":"10.2989/1814232X.2021.1961166","DOIUrl":"https://doi.org/10.2989/1814232X.2021.1961166","url":null,"abstract":"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 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.","PeriodicalId":7719,"journal":{"name":"African Journal of Marine Science","volume":"43 1","pages":"367 - 387"},"PeriodicalIF":1.2,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46982550","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}
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