Pub Date : 2023-12-21DOI: 10.1017/s0025315423000899
Ruth H. Leeney, David A. Ebert, Kolette Grobler
Warren's sixgill sawshark, Pliotrema warreni, is confirmed for the first time in Namibian waters, from two specimens. One specimen was collected by fisheries observers on a vessel fishing in southern Namibian waters in March 2010. The other was found dead on a beach in central coastal Namibia, in August 2014. The West African catshark, Scyliorhinus cervigoni, is documented for the first time in northern Namibia, from a specimen recorded during surveys of chondrichthyan bycatch on a commercial bottom trawler. This extends the species' range southwards from Angola. Records of bull sharks Carcharhinus leucas are also documented, providing a better understanding of their distribution in Namibia. Several anglers have reported catching bull sharks in the Kunene River (from the riverbank on the Namibian side) and just south of the river mouth, along the Namibian coast.
{"title":"First record of Warren's sixgill sawshark Pliotrema warreni (Pristiophoriformes: Pristiophoridae) and the West African catshark Scyliorhinus cervigoni (Carcharhiniformes: Scyliorhinidae) in Namibia, and notes on the habitat of the bull shark Carcharhinus leucas (Carcharhiniformes: Carcharhinidae)","authors":"Ruth H. Leeney, David A. Ebert, Kolette Grobler","doi":"10.1017/s0025315423000899","DOIUrl":"https://doi.org/10.1017/s0025315423000899","url":null,"abstract":"<p>Warren's sixgill sawshark, <span>Pliotrema warreni</span>, is confirmed for the first time in Namibian waters, from two specimens. One specimen was collected by fisheries observers on a vessel fishing in southern Namibian waters in March 2010. The other was found dead on a beach in central coastal Namibia, in August 2014. The West African catshark, <span>Scyliorhinus cervigoni</span>, is documented for the first time in northern Namibia, from a specimen recorded during surveys of chondrichthyan bycatch on a commercial bottom trawler. This extends the species' range southwards from Angola. Records of bull sharks <span>Carcharhinus leucas</span> are also documented, providing a better understanding of their distribution in Namibia. Several anglers have reported catching bull sharks in the Kunene River (from the riverbank on the Namibian side) and just south of the river mouth, along the Namibian coast.</p>","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"9 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138824816","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 : 2023-12-21DOI: 10.1017/s0025315423000863
Marcos D. Calle-Morán, Héctor M. Erazo-Garcés, Ana R. Hernández-Téllez, Felipe Galván-Magaña, Colombo Estupiñán-Montaño
Shortfin mako shark, Isurus oxyrinchus, is listed as an endangered species with declining global population. Thus, studies regarding its biology and ecology are important to recommend fishery management and conservation measures. This study aimed to determine the diet composition and feeding habits of I. oxyrinchus in Ecuadorian waters. Samples were obtained from Santa Rosa fishing port (Ecuador). The total length (LT), sex and sexual characteristics were recorded, and stomach contents were collected. A total of 142 individuals were recorded, comprising 81 females (104–295 cm LT) and 61 males (127–245 cm LT). A total of 24 prey species were identified, including crustaceans, cephalopods, teleosts and cetaceans. According to the Prey-Specific Index of Relative Importance (PSIRI), the main prey taxa were the ommastrephid squid, Dosidicus gigas (42.57%) and Sthenoteuthis oualaniensis (21.04%), followed by fish from the family Hemiramphidae (11.85%). Isurus oxyrinchus is a specialist predator that preferred a low number of prey (Bi = 0.25), both by sex (Bi; females = 0.29 and males = 0.34) and life stages (Bi; juveniles = 0.27 and adults = 0.37). The trophic overlap was medium for sexes (J = 0.54) and biological cycle phases (J = 0.42). Trophic level (TLk) was 4.47, indicating that I. oxyrinchus is a tertiary predator. This information will help in fisheries management based on an ecosystem approach, where this species fulfils an ecological role, and its interactions with other species allow us to understand how the flow of nutrients and energy occurs within an ecosystem.
{"title":"Feeding ecology of the shortfin mako shark, Isurus oxyrinchus, in the Ecuadorian Pacific Ocean","authors":"Marcos D. Calle-Morán, Héctor M. Erazo-Garcés, Ana R. Hernández-Téllez, Felipe Galván-Magaña, Colombo Estupiñán-Montaño","doi":"10.1017/s0025315423000863","DOIUrl":"https://doi.org/10.1017/s0025315423000863","url":null,"abstract":"<p>Shortfin mako shark, <span>Isurus oxyrinchus</span>, is listed as an endangered species with declining global population. Thus, studies regarding its biology and ecology are important to recommend fishery management and conservation measures. This study aimed to determine the diet composition and feeding habits of <span>I. oxyrinchus</span> in Ecuadorian waters. Samples were obtained from Santa Rosa fishing port (Ecuador). The total length (L<span>T</span>), sex and sexual characteristics were recorded, and stomach contents were collected. A total of 142 individuals were recorded, comprising 81 females (104–295 cm L<span>T</span>) and 61 males (127–245 cm L<span>T</span>). A total of 24 prey species were identified, including crustaceans, cephalopods, teleosts and cetaceans. According to the Prey-Specific Index of Relative Importance (PSIRI), the main prey taxa were the ommastrephid squid, <span>Dosidicus gigas</span> (42.57%) and <span>Sthenoteuthis oualaniensis</span> (21.04%), followed by fish from the family Hemiramphidae (11.85%). <span>Isurus oxyrinchus</span> is a specialist predator that preferred a low number of prey (<span>Bi</span> = 0.25), both by sex (<span>Bi</span>; females = 0.29 and males = 0.34) and life stages (<span>Bi</span>; juveniles = 0.27 and adults = 0.37). The trophic overlap was medium for sexes (<span>J</span> = 0.54) and biological cycle phases (<span>J</span> = 0.42). Trophic level (<span>TL<span>k</span></span>) was 4.47, indicating that <span>I. oxyrinchus</span> is a tertiary predator. This information will help in fisheries management based on an ecosystem approach, where this species fulfils an ecological role, and its interactions with other species allow us to understand how the flow of nutrients and energy occurs within an ecosystem.</p>","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138824622","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}
Over the years as a part of many fishery surveys, considerable number of stomiiform fishes were collected by the Centre for Marine Living Resources and Ecology (CMLRE) Research Vessel ‘Sagar Sampada’. The collection came from throughout the Indian EEZ and some from the western Indian Ocean. However, a systematic identification of these fishes had never been carried out prior to this paper. Thirty-four species were identified and it was found that eight species were new records to India and one to peninsular India. Among the records, two species, Photonectes paxtoni Flynn and Klepadlo, 2012 and Photonectes barnetti Klepadlo, 2011, are collected from the Indian Ocean for the first time. The paper provides a detailed report on all the new records and a list of stomiiform species collected during these surveys. Differences in barbel morphology observed for many of the stomiids are discussed.
{"title":"An updated checklist of Stomiiformes from Indian waters with nine new records","authors":"Rajeev Rajakrishnan, Meleppura Rajeeshkumar, Sherine Sonia Cubelio, Narayanane Saravanane","doi":"10.1017/s0025315423000838","DOIUrl":"https://doi.org/10.1017/s0025315423000838","url":null,"abstract":"Over the years as a part of many fishery surveys, considerable number of stomiiform fishes were collected by the Centre for Marine Living Resources and Ecology (CMLRE) Research Vessel ‘Sagar Sampada’. The collection came from throughout the Indian EEZ and some from the western Indian Ocean. However, a systematic identification of these fishes had never been carried out prior to this paper. Thirty-four species were identified and it was found that eight species were new records to India and one to peninsular India. Among the records, two species, <jats:italic>Photonectes paxtoni</jats:italic> Flynn and Klepadlo, 2012 and <jats:italic>Photonectes barnetti</jats:italic> Klepadlo, 2011, are collected from the Indian Ocean for the first time. The paper provides a detailed report on all the new records and a list of stomiiform species collected during these surveys. Differences in barbel morphology observed for many of the stomiids are discussed.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"69 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138568158","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 : 2023-12-06DOI: 10.1017/s0025315423000772
Ryutaro Goto, Taigi Sato, Hiroki Nakajima, Takahiro Sugiyama, Hiroshi Ishikawa
Sagamiscintilla thalassemicola (Bivalvia: Galeommatoidea: Galeommatidae) is a rare ectocommensal bivalve that lives on the proboscis of echiuran worms, Anelassorhynchus spp. (Annelida: Thalassematidae: Thalassematinae: Thalassematini), and has been known only from the temperate zones of Japan. In this study, we found S. thalassemicola on the proboscis of the large echiuran Ochetostoma sp. (Thalassematidae: Thalassematinae: Thalassematini) on intertidal flats of three islands of the Ryukyu Archipelago, southern Japan. These are the first records of S. thalassemicola on non-Anelassorhynchus hosts and also from the subtropical regions. Additionally, we also collected S. thalassemicola from an intertidal flat of Kushimoto, Wakayama, Kii Peninsula, Japan, which is an update of the easternmost record of this species. The genetic differences in the mitochondrial cytochrome c oxidase subunit I and nuclear internal transcribed spacer 2 genes among S. thalassemicola, including those with Ochetostoma sp. from the subtropical region and with Anelassorhynchus spp. from the temperate region, can be considered within the intraspecific variation. These suggest that S. thalassemicola uses different echiuran hosts in the temperate and subtropical regions, respectively.
{"title":"Latitudinal shift of the associated hosts in Sagamiscintilla thalassemicola (Galeommatoidea: Galeommatidae), a rare ectosymbiotic bivalve that lives on the proboscis of echiuran worms","authors":"Ryutaro Goto, Taigi Sato, Hiroki Nakajima, Takahiro Sugiyama, Hiroshi Ishikawa","doi":"10.1017/s0025315423000772","DOIUrl":"https://doi.org/10.1017/s0025315423000772","url":null,"abstract":"<jats:italic>Sagamiscintilla thalassemicola</jats:italic> (Bivalvia: Galeommatoidea: Galeommatidae) is a rare ectocommensal bivalve that lives on the proboscis of echiuran worms, <jats:italic>Anelassorhynchus</jats:italic> spp. (Annelida: Thalassematidae: Thalassematinae: Thalassematini), and has been known only from the temperate zones of Japan. In this study, we found <jats:italic>S. thalassemicola</jats:italic> on the proboscis of the large echiuran <jats:italic>Ochetostoma</jats:italic> sp. (Thalassematidae: Thalassematinae: Thalassematini) on intertidal flats of three islands of the Ryukyu Archipelago, southern Japan. These are the first records of <jats:italic>S. thalassemicola</jats:italic> on non-<jats:italic>Anelassorhynchus</jats:italic> hosts and also from the subtropical regions. Additionally, we also collected <jats:italic>S. thalassemicola</jats:italic> from an intertidal flat of Kushimoto, Wakayama, Kii Peninsula, Japan, which is an update of the easternmost record of this species. The genetic differences in the mitochondrial cytochrome <jats:italic>c</jats:italic> oxidase subunit I and nuclear internal transcribed spacer 2 genes among <jats:italic>S. thalassemicola</jats:italic>, including those with <jats:italic>Ochetostoma</jats:italic> sp. from the subtropical region and with <jats:italic>Anelassorhynchus</jats:italic> spp. from the temperate region, can be considered within the intraspecific variation. These suggest that <jats:italic>S. thalassemicola</jats:italic> uses different echiuran hosts in the temperate and subtropical regions, respectively.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"21 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138512060","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 : 2023-11-28DOI: 10.1017/s0025315423000814
Mohamad Hassan, Alaa Alchikh Ahmad
Here, we report the first validated record of the non-indigenous grouper species Epinephelus areolatus (Perciformes: Serranidae) along the Mediterranean coast of Syria. A single specimen of E. areolatus (Forsskål, 1775), was found on 29 September 2021 during a recurrent ichthyological survey, in a rocky habitat from the Mediterranean coast of Syria. This represents the first confirmed record of this species, native to the Red Sea, for the Syrian waters and the fourth for the Mediterranean Sea. The present record fills the gap with species distribution along the eastern Mediterranean and provides further evidence that the environmental alterations due to the combination of human activities and climate change render the Mediterranean waters increasingly likely to accommodate tropical species, possibly at the expense of the native ones.
{"title":"The first validated record of Epinephelus areolatus (Forsskål, 1775) (Perciformes: Serranidae) from Syrian marine waters","authors":"Mohamad Hassan, Alaa Alchikh Ahmad","doi":"10.1017/s0025315423000814","DOIUrl":"https://doi.org/10.1017/s0025315423000814","url":null,"abstract":"Here, we report the first validated record of the non-indigenous grouper species <jats:italic>Epinephelus areolatus</jats:italic> (Perciformes: Serranidae) along the Mediterranean coast of Syria. A single specimen of <jats:italic>E. areolatus</jats:italic> (Forsskål, 1775), was found on 29 September 2021 during a recurrent ichthyological survey, in a rocky habitat from the Mediterranean coast of Syria. This represents the first confirmed record of this species, native to the Red Sea, for the Syrian waters and the fourth for the Mediterranean Sea. The present record fills the gap with species distribution along the eastern Mediterranean and provides further evidence that the environmental alterations due to the combination of human activities and climate change render the Mediterranean waters increasingly likely to accommodate tropical species, possibly at the expense of the native ones.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"14 8","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138512025","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 : 2023-11-24DOI: 10.1017/s0025315423000826
Kimberley Mills, Kate Mortimer
Shovelhead worms are common polychaetes around the British Isles and have been recorded in numerous ecological surveys. Yet, understanding of their habitat conditions is poor, based heavily on visual observations of sediments from historical records. In this study, the drivers of abundance and geographical distribution of two morphologically and behaviourally diverse species Magelona alleni and Magelona minuta are investigated by reanalysing sediment characteristics and depths from museum marine monitoring surveys. Although both species are historically associated with muddy sediments, the records herein suggest that M. alleni occurs in an extensive range of sediments, but is more abundant at localities with more than 25% sand. In comparison, M. minuta shows a negative linear relationship between grain diameter and abundance, corroborating previous work that the species is abundant in fine-grained mud. The depth records show that while M. alleni predominates below 60 m, M. minuta is a distinct offshore species. These differences may be attributed to the interspecific variation in morphology and motility between the species: M. alleni is stout and tube-dwelling, while M. minuta is fragile, small, and fairly motile. To corroborate these findings, sediment grains from tubes of M. alleni were classified using the Udden–Wentworth grain size scale and suggest sand is the key component for tube construction. Overall, this study highlights that sediment parameters for M. alleni have been misinterpreted and generalised in historical records, emphasising the importance of quantitative sediment analysis in defining the habitat of Magelona.
{"title":"Impact of historic sediment characterisation on predicting polychaete distributions: a case study of so-called muddy habitat shovelhead worms (Annelida: Magelonidae)","authors":"Kimberley Mills, Kate Mortimer","doi":"10.1017/s0025315423000826","DOIUrl":"https://doi.org/10.1017/s0025315423000826","url":null,"abstract":"Shovelhead worms are common polychaetes around the British Isles and have been recorded in numerous ecological surveys. Yet, understanding of their habitat conditions is poor, based heavily on visual observations of sediments from historical records. In this study, the drivers of abundance and geographical distribution of two morphologically and behaviourally diverse species <jats:italic>Magelona alleni</jats:italic> and <jats:italic>Magelona minuta</jats:italic> are investigated by reanalysing sediment characteristics and depths from museum marine monitoring surveys. Although both species are historically associated with muddy sediments, the records herein suggest that <jats:italic>M. alleni</jats:italic> occurs in an extensive range of sediments, but is more abundant at localities with more than 25% sand. In comparison, <jats:italic>M. minuta</jats:italic> shows a negative linear relationship between grain diameter and abundance, corroborating previous work that the species is abundant in fine-grained mud. The depth records show that while <jats:italic>M. alleni</jats:italic> predominates below 60 m, <jats:italic>M. minuta</jats:italic> is a distinct offshore species. These differences may be attributed to the interspecific variation in morphology and motility between the species: <jats:italic>M. alleni</jats:italic> is stout and tube-dwelling, while <jats:italic>M. minuta</jats:italic> is fragile, small, and fairly motile. To corroborate these findings, sediment grains from tubes of <jats:italic>M. alleni</jats:italic> were classified using the Udden–Wentworth grain size scale and suggest sand is the key component for tube construction. Overall, this study highlights that sediment parameters for <jats:italic>M. alleni</jats:italic> have been misinterpreted and generalised in historical records, emphasising the importance of quantitative sediment analysis in defining the habitat of <jats:italic>Magelona</jats:italic>.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"12 3","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138511988","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}
Record-sized specimens of the ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus were caught by single-day trawlers off Pamban Island in the Gulf of Mannar, Tamil Nadu, India during 2021 and 2022. All were landed at the Pamban Therkuvadi Fish Landing Centre (FLC). The largest ornate eagle ray was 384 cm disc width (DW) and weighed 530 kg, setting a new global record for the species, as the previous maximum size was reported to be 300 cm DW. This specimen was landed on 19 July 2021. Another large specimen of this species (360 cm DW and total weight of 453 kg) was caught and landed on 12 August 2022. The landed mangrove whipray was 153 cm DW and 150 kg total weight, larger than the previously reported maximum size of 141 cm DW. The morphometrics, stomach contents and reproductive state were studied. One of the eagle rays was a pregnant female with three full-term embryos in the uterus, while the whipray was a spent female. The main prey species in the stomach of eagle ray was big-eye scad Selar crumenophthalmus. The mangrove whipray had fed on a range of fish (pigface bream, goatfish, silverbellies, silverbiddies and lesser sardine) and octopus.
{"title":"Biological observations and new maximum reported sizes for two threatened rays: ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus from the Gulf of Mannar, India","authors":"Remya Lalitha, Sujitha Thomas, Shoba Joe Kizhakudan, Thirumalaiselvan Shanmugam, Gandhi Ayyakannu, Midhun Muthayan, Rajkumar Raja, Vetrivel Vedhagiri, Rajendran Umayan, Shanmuganathan Kalimuthu, Prakash Murugesan","doi":"10.1017/s0025315423000796","DOIUrl":"https://doi.org/10.1017/s0025315423000796","url":null,"abstract":"Record-sized specimens of the ornate eagle ray <jats:italic>Aetomylaeus vespertilio</jats:italic> and mangrove whipray <jats:italic>Urogymnus granulatus</jats:italic> were caught by single-day trawlers off Pamban Island in the Gulf of Mannar, Tamil Nadu, India during 2021 and 2022. All were landed at the Pamban Therkuvadi Fish Landing Centre (FLC). The largest ornate eagle ray was 384 cm disc width (DW) and weighed 530 kg, setting a new global record for the species, as the previous maximum size was reported to be 300 cm DW. This specimen was landed on 19 July 2021. Another large specimen of this species (360 cm DW and total weight of 453 kg) was caught and landed on 12 August 2022. The landed mangrove whipray was 153 cm DW and 150 kg total weight, larger than the previously reported maximum size of 141 cm DW. The morphometrics, stomach contents and reproductive state were studied. One of the eagle rays was a pregnant female with three full-term embryos in the uterus, while the whipray was a spent female. The main prey species in the stomach of eagle ray was big-eye scad <jats:italic>Selar crumenophthalmus</jats:italic>. The mangrove whipray had fed on a range of fish (pigface bream, goatfish, silverbellies, silverbiddies and lesser sardine) and octopus.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"15 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138512023","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 : 2023-11-21DOI: 10.1017/s0025315423000802
Melih Ertan Çinar, Aytaç Özgül
Didemnum vexillum is an aggressive, rapidly growing colonial ascidian and regarded as a global alien invasive species in temperate waters. It has recently become established in the western Mediterranean and the vectors of its introduction were assumed to be shipping or oyster trade. A dense settlement of it was encountered on nets of the bluefin tuna (Thunnus thynnus) cages placed at 60–65 m depths off the İzmir Peninsula (eastern Aegean Sea, eastern Mediterranean) in December 2022. It had considerably clogged net's eye openings, hindering water circulations inside cages. It had a vertical distributional pattern on 35 m long-nets, occurring solely on depths from surface down to 15 m, around where a summer thermocline develops. It has entirely replaced the native black mussel Mytilus galloprovincialis on nets. This colonial ascidian changed the routine cleaning procedure of nets in the farming. Three possible ways of its introduction to the eastern Mediterranean were proposed, but the most reasonable one is its secondary transfer via nets or ships from Malta. Mechanisms of its invasion biology and behaviour should be studied and monitored in the region.
{"title":"Clogging nets-Didemnum vexillum (Tunicata: Ascidiacea) is in action in the eastern Mediterranean","authors":"Melih Ertan Çinar, Aytaç Özgül","doi":"10.1017/s0025315423000802","DOIUrl":"https://doi.org/10.1017/s0025315423000802","url":null,"abstract":"<jats:italic>Didemnum vexillum</jats:italic> is an aggressive, rapidly growing colonial ascidian and regarded as a global alien invasive species in temperate waters. It has recently become established in the western Mediterranean and the vectors of its introduction were assumed to be shipping or oyster trade. A dense settlement of it was encountered on nets of the bluefin tuna (<jats:italic>Thunnus thynnus</jats:italic>) cages placed at 60–65 m depths off the İzmir Peninsula (eastern Aegean Sea, eastern Mediterranean) in December 2022. It had considerably clogged net's eye openings, hindering water circulations inside cages. It had a vertical distributional pattern on 35 m long-nets, occurring solely on depths from surface down to 15 m, around where a summer thermocline develops. It has entirely replaced the native black mussel <jats:italic>Mytilus galloprovincialis</jats:italic> on nets. This colonial ascidian changed the routine cleaning procedure of nets in the farming. Three possible ways of its introduction to the eastern Mediterranean were proposed, but the most reasonable one is its secondary transfer via nets or ships from Malta. Mechanisms of its invasion biology and behaviour should be studied and monitored in the region.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"11 11","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138511989","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 : 2023-11-21DOI: 10.1017/s0025315423000784
Welly Qwabe, Toufiek Samaai, Jean M. Harris, Ryan M. Palmer, Sven E. Kerwath
A dense Ecklonia radiata (Laminariales) kelp forest extending at least 35 km has been found between 45 and 60 m depth range within the mesophotic zone inside the iSimangaliso marine-protected area (MPA) at the iSimangaliso Wetland park World Heritage Site on the east coast of South Africa. This is the first visual confirmation of the occurrence of E. radiata beds in subtropical South Africa, in an area situated between the tropical and subtropical bioregions, in an area that spans the Natal and Delagoa bioregions of the south-western Indian Ocean, more than 350 km north of its previously documented South African range. The kelp was found to be present across the length of the MPA, but dense beds were present only in the southern Natal bioregion, with sparse occurrences observed elsewhere on soft-coral and sponge-dominated reefs in the upper mesophotic zone. The footage was collected in November 2020, May 2021 and November 2022 during remotely operated vehicle and drop camera surveys of the mesophotic zone inside the MPA. This discovery adds to the body of knowledge on the global distribution of Laminariales populations in deep tropical and subtropical settings and the diversity of habitats within South Africa's largest coastal MPA.
{"title":"First mesophotic Ecklonia radiata (Laminariales) records within the iSimangaliso Wetland Park marine-protected area, east coast, South Africa","authors":"Welly Qwabe, Toufiek Samaai, Jean M. Harris, Ryan M. Palmer, Sven E. Kerwath","doi":"10.1017/s0025315423000784","DOIUrl":"https://doi.org/10.1017/s0025315423000784","url":null,"abstract":"A dense <jats:italic>Ecklonia radiata</jats:italic> (Laminariales) kelp forest extending at least 35 km has been found between 45 and 60 m depth range within the mesophotic zone inside the iSimangaliso marine-protected area (MPA) at the iSimangaliso Wetland park World Heritage Site on the east coast of South Africa. This is the first visual confirmation of the occurrence of <jats:italic>E. radiata</jats:italic> beds in subtropical South Africa, in an area situated between the tropical and subtropical bioregions, in an area that spans the Natal and Delagoa bioregions of the south-western Indian Ocean, more than 350 km north of its previously documented South African range. The kelp was found to be present across the length of the MPA, but dense beds were present only in the southern Natal bioregion, with sparse occurrences observed elsewhere on soft-coral and sponge-dominated reefs in the upper mesophotic zone. The footage was collected in November 2020, May 2021 and November 2022 during remotely operated vehicle and drop camera surveys of the mesophotic zone inside the MPA. This discovery adds to the body of knowledge on the global distribution of Laminariales populations in deep tropical and subtropical settings and the diversity of habitats within South Africa's largest coastal MPA.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":"14 10","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138512024","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 : 2023-09-07DOI: 10.1017/S0025315423000553
Amairani Hernández-Aparicio, F. Galván‐Magaña, M. D. R. Simental‐Anguiano
Abstract The sharpnose shark (Rhizoprionodon longurio) is among the top three shark species captured by artisanal fisheries of the Gulf of California. This study includes information regarding the feeding habits of this species using the stomach contents of 70 individuals ranged from 54 to 109 cm in total length (TL). Out of the 16 prey items identified, fish of the families Scombridae (Scomber japonicus; prey-specific relative importance index [%PSIRI] = 6.3) and Batrachoididae (%PSIRI = 5.5), the cephalopod Lolliguncula spp. (%PSIRI = 6.3), and the crustacean Pleuroncodes planipes (%PSIRI = 4.3) were the most important prey. Only female stomachs were obtained (N = 19) in the central area of the gulf, and the PSIRI indicated that the preferred prey were the cephalopod Lolliguncula spp. (%PSIRI = 10.5) and fish of the Sparidae family (Calamus brachysomus; %PSIRI = 5.8). The number of stomachs was not sufficient to analyse differences by sex. Regarding its trophic position, R. longurio was a tertiary consumer (TLK = 4.4). A TLK = 4.4 was calculated for the central area, and a TLK = 4.3 for the southern area. According to Levin's index (Bi), this shark is a specialist predator in the whole study area (Bi = 0.19), including the centre (Bi = 0.29). Conversely, it was considered a generalist predator in the southern area (Bi = 0.63). The high quantity of empty stomachs could relate to the time the sharks were caught in fishing a gear.
{"title":"Feeding habits of the sharpnose shark Rhizoprionodon longurio on the west coast of the Gulf of California, Mexico","authors":"Amairani Hernández-Aparicio, F. Galván‐Magaña, M. D. R. Simental‐Anguiano","doi":"10.1017/S0025315423000553","DOIUrl":"https://doi.org/10.1017/S0025315423000553","url":null,"abstract":"Abstract The sharpnose shark (Rhizoprionodon longurio) is among the top three shark species captured by artisanal fisheries of the Gulf of California. This study includes information regarding the feeding habits of this species using the stomach contents of 70 individuals ranged from 54 to 109 cm in total length (TL). Out of the 16 prey items identified, fish of the families Scombridae (Scomber japonicus; prey-specific relative importance index [%PSIRI] = 6.3) and Batrachoididae (%PSIRI = 5.5), the cephalopod Lolliguncula spp. (%PSIRI = 6.3), and the crustacean Pleuroncodes planipes (%PSIRI = 4.3) were the most important prey. Only female stomachs were obtained (N = 19) in the central area of the gulf, and the PSIRI indicated that the preferred prey were the cephalopod Lolliguncula spp. (%PSIRI = 10.5) and fish of the Sparidae family (Calamus brachysomus; %PSIRI = 5.8). The number of stomachs was not sufficient to analyse differences by sex. Regarding its trophic position, R. longurio was a tertiary consumer (TLK = 4.4). A TLK = 4.4 was calculated for the central area, and a TLK = 4.3 for the southern area. According to Levin's index (Bi), this shark is a specialist predator in the whole study area (Bi = 0.19), including the centre (Bi = 0.29). Conversely, it was considered a generalist predator in the southern area (Bi = 0.63). The high quantity of empty stomachs could relate to the time the sharks were caught in fishing a gear.","PeriodicalId":17477,"journal":{"name":"Journal of the Marine Biological Association of the United Kingdom","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41810442","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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