S. Mishima, Satoshi Kobayashi, Katsumasa Yamada, Y. Henmi
: The intertidal hermit crab Pagurus nigrofascia reproduces in March in Fukuoka, Japan. The embryos remain in diapause until October, begin to develop in November, and most broods hatch in December. This study examined the effects of photoperiod and temperature on embryonic diapause termination (EDT) in both laboratory and field condi -tions. Females with diapause eggs were maintained in the laboratory under three different photoperiod/temperature re -gimes: constant (14L/10D, 22° C), decreasing photoperiod condition (from 12L/12D to 9.8L/14.2D, 22 °C), and decreasing temperature condition (14L/10D, from 22 °C to 10° C). The EDT date was compared among four groups: the above three experimental groups and the field group. The dates at which > 50% of females possessed eggs after the EDT were November 10 (constant), October 30 (decreasing photoperiod), September 27 (decreasing temperature), and November 4 (field). The mean duration until EDT was 82 days (constant), 67 days (decreasing photoperiod), and 36 days (decreasing temperature). Diapause was significantly shorter under both the decreasing photoperiod and the decreasing temperature conditions compared to the constant. Thus, EDT was strongly affected by temperature but weakly altered by photope riod. This study is the first to report the influence of photoperiod and temperature on EDT in decapod crustaceans.
{"title":"The effects of photoperiod and temperature on embryonic diapause termination in the hermit crab Pagurus nigrofascia","authors":"S. Mishima, Satoshi Kobayashi, Katsumasa Yamada, Y. Henmi","doi":"10.3800/PBR.16.79","DOIUrl":"https://doi.org/10.3800/PBR.16.79","url":null,"abstract":": The intertidal hermit crab Pagurus nigrofascia reproduces in March in Fukuoka, Japan. The embryos remain in diapause until October, begin to develop in November, and most broods hatch in December. This study examined the effects of photoperiod and temperature on embryonic diapause termination (EDT) in both laboratory and field condi -tions. Females with diapause eggs were maintained in the laboratory under three different photoperiod/temperature re -gimes: constant (14L/10D, 22° C), decreasing photoperiod condition (from 12L/12D to 9.8L/14.2D, 22 °C), and decreasing temperature condition (14L/10D, from 22 °C to 10° C). The EDT date was compared among four groups: the above three experimental groups and the field group. The dates at which > 50% of females possessed eggs after the EDT were November 10 (constant), October 30 (decreasing photoperiod), September 27 (decreasing temperature), and November 4 (field). The mean duration until EDT was 82 days (constant), 67 days (decreasing photoperiod), and 36 days (decreasing temperature). Diapause was significantly shorter under both the decreasing photoperiod and the decreasing temperature conditions compared to the constant. Thus, EDT was strongly affected by temperature but weakly altered by photope riod. This study is the first to report the influence of photoperiod and temperature on EDT in decapod crustaceans.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44362502","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}
: ROV dive surveys were carried out inside and outside the Sumisu Caldera, located in the Izu-Bonin Arc. The caldera is hydrothermally active and nourishes a unique chemosynthetic ecosystem, which includes Bathymo-diolus mussel beds and vestimentiferan tubeworms. Sixty-one gelatinous zooplankton morphotaxa were observed (21 ctenophores, 16 siphonophores, 10 hydromedusae, 4 scyphozoans and 10 thaliaceans), and notes on their taxonomy and fine-scale distributional data are presented. The vertical distribution patterns of gelatinous zooplankton clearly dif fered inside and outside the caldera: three gelatinous zooplankton morphotaxa, the ctenophores Lobata sp. “ Boli ” and undescribed Lobata “ No auricles ” , and the hydromedusa Earleria bruuni, were highly abundant inside, but not outside, of the caldera. Thaliaceans and Solmissus incisa s.l. (Narcomedusae) were distributed over a wider vertical range inside the caldera than outside. The utility of ROV video records for investigating midwater gelatinous zooplankton taxonomy and ecology is discussed, and the efficacy of ROV investigations for this type of research is shown.
{"title":"Gelatinous zooplankton community around a hydrothermally active deep-sea caldera: results from ROV video records","authors":"Mitsuko Hidaka, J. Nishikawa, D. Lindsay","doi":"10.3800/PBR.16.40","DOIUrl":"https://doi.org/10.3800/PBR.16.40","url":null,"abstract":": ROV dive surveys were carried out inside and outside the Sumisu Caldera, located in the Izu-Bonin Arc. The caldera is hydrothermally active and nourishes a unique chemosynthetic ecosystem, which includes Bathymo-diolus mussel beds and vestimentiferan tubeworms. Sixty-one gelatinous zooplankton morphotaxa were observed (21 ctenophores, 16 siphonophores, 10 hydromedusae, 4 scyphozoans and 10 thaliaceans), and notes on their taxonomy and fine-scale distributional data are presented. The vertical distribution patterns of gelatinous zooplankton clearly dif fered inside and outside the caldera: three gelatinous zooplankton morphotaxa, the ctenophores Lobata sp. “ Boli ” and undescribed Lobata “ No auricles ” , and the hydromedusa Earleria bruuni, were highly abundant inside, but not outside, of the caldera. Thaliaceans and Solmissus incisa s.l. (Narcomedusae) were distributed over a wider vertical range inside the caldera than outside. The utility of ROV video records for investigating midwater gelatinous zooplankton taxonomy and ecology is discussed, and the efficacy of ROV investigations for this type of research is shown.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41552545","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}
S. Teng, Ing Kuo Law, Afiqah Hamilton Hanifah, Othman Bojo, F. A. Idrus, Aini Hannani Naqiah Abdul Mannaf, P. Lim, C. Leaw
: Mass mortality of fish ( ∼ 8,500 fishes), mainly Oreochromis placidus , was noted in a man-made lake located at Kuching, Sarawak (Malaysia). A field investigation was conducted to collect water samples and fishes. Patches of discoloration in brick red were observed in the lake and clear oil layer was found on the surface of the water. Microscopic observation and enumeration of the water samples showed that the plankton composition was dominated by a green algal species Botryococcus sp., with the colony densities ranging 1.2 × 10 3 –7.4 × 10 6 colonies L − 1 . Detailed morphological assessment by light microscopy revealed the dominant species as Botryococcus braunii Kützing. Mo lecular characterization using an rDNA marker further supported the species identity as B. braunii in the L race. Fish gill observation showed that cells of B. braunii and the oily substances were found in the dead fish gills. The race-L B. braunii bloom was reported, for the first time, to be associated with a fish kill event in a freshwater lake in Malaysia and confirmed the species as one of the algal types causing harmful effects to the environment.
{"title":"Bloom of a freshwater green alga Botryococcus braunii (Botryococcaceae, Trebouxiophyceae) and the associated mass fish mortality in a man-made lake, Sarawak, Malaysia","authors":"S. Teng, Ing Kuo Law, Afiqah Hamilton Hanifah, Othman Bojo, F. A. Idrus, Aini Hannani Naqiah Abdul Mannaf, P. Lim, C. Leaw","doi":"10.3800/PBR.16.59","DOIUrl":"https://doi.org/10.3800/PBR.16.59","url":null,"abstract":": Mass mortality of fish ( ∼ 8,500 fishes), mainly Oreochromis placidus , was noted in a man-made lake located at Kuching, Sarawak (Malaysia). A field investigation was conducted to collect water samples and fishes. Patches of discoloration in brick red were observed in the lake and clear oil layer was found on the surface of the water. Microscopic observation and enumeration of the water samples showed that the plankton composition was dominated by a green algal species Botryococcus sp., with the colony densities ranging 1.2 × 10 3 –7.4 × 10 6 colonies L − 1 . Detailed morphological assessment by light microscopy revealed the dominant species as Botryococcus braunii Kützing. Mo lecular characterization using an rDNA marker further supported the species identity as B. braunii in the L race. Fish gill observation showed that cells of B. braunii and the oily substances were found in the dead fish gills. The race-L B. braunii bloom was reported, for the first time, to be associated with a fish kill event in a freshwater lake in Malaysia and confirmed the species as one of the algal types causing harmful effects to the environment.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49307667","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}
: Phyllochaetopterus (Annelida: Chaetopteridae) is a diverse genus of tube-dwelling polychaetes found in a wide range of marine environments from subtidal to abyssal depths, including chemosynthesis-based ecosystems. The Shinkai Seep Field (SSF) is a serpentinite-hosted system in the Mariana Trench, where the deepest-known Phyllochaetopterus polychaetes inhabit the surfaces of brucite/carbonate chimneys. Despite all specimens collected from SSF being morphologically consistent with P. polus originally described from a deep-sea hot vent on the Mid-Atlantic Ridge, molecular barcoding using the mitochondrial cytochrome c oxidase subunit I (COI) gene revealed at least three cryptic lineages, none of which corresponded to P. polus . Phylogenetic reconstruction re covered P. polus embedded among the three SSF lineages, confirming their close relationship. These results warrant careful examina-tion of Phyllochaetopterus from other regions using integrative taxonomy in order to understand its true diversity and pinpoint further taxonomically informative morphological characters.
{"title":"Cryptic diversity of the tube-dwelling polychaete Phyllochaetopterus in the Shinkai Seep Field, Mariana Trench","authors":"H. Watanabe, Chong Chen, E. Nishi, Y. Ohara","doi":"10.3800/PBR.16.73","DOIUrl":"https://doi.org/10.3800/PBR.16.73","url":null,"abstract":": Phyllochaetopterus (Annelida: Chaetopteridae) is a diverse genus of tube-dwelling polychaetes found in a wide range of marine environments from subtidal to abyssal depths, including chemosynthesis-based ecosystems. The Shinkai Seep Field (SSF) is a serpentinite-hosted system in the Mariana Trench, where the deepest-known Phyllochaetopterus polychaetes inhabit the surfaces of brucite/carbonate chimneys. Despite all specimens collected from SSF being morphologically consistent with P. polus originally described from a deep-sea hot vent on the Mid-Atlantic Ridge, molecular barcoding using the mitochondrial cytochrome c oxidase subunit I (COI) gene revealed at least three cryptic lineages, none of which corresponded to P. polus . Phylogenetic reconstruction re covered P. polus embedded among the three SSF lineages, confirming their close relationship. These results warrant careful examina-tion of Phyllochaetopterus from other regions using integrative taxonomy in order to understand its true diversity and pinpoint further taxonomically informative morphological characters.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43500699","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}
We estimated the production of the copepod Calanus sinicus, including somatic production of copepodite stage 1 (CI) to copepodite stage 5 (CV) and egg production of adult females, to elucidate the role of C. sinicus during spring in the northern East China Sea, including the southern waters of Korea. To estimate the somatic production of the copepodites, an empirical equation for broadcasters (Hirst & Bunker 2003) was used. The total biomass of the C. sinicus population, including CI to adult males and females, ranged from 0.11 to 30.23 mg C m−3, with a mean of 8.69 mg C m−3. The egg production rate (EPR) of adult females of C. sinicus, measured over 24 h of shipboard incubation, ranged from 0 to 14.9 eggs female−1 day−1 (mean 5.8 eggs female−1 day−1), equivalent to mean 33.6 μg C m−3 day−1. The weight-specific EPR (WSEPR) of adult females averaged 0.023 day−1, and significantly increased with increasing water temperature at 5 m depth and surface chlorophyll a concentration, respectively. WSEPR decreased with increasing body mass of individual adult females. The total production of the C. sinicus population ranged from 0.02 to 3.67 mg C m−3 day−1 (mean 0.91 mg C m−3 day−1) and the depth-integrated mean total production was estimated to be 52.72 mg C m−2 day−1. CV production accounted for 54% of the total production. By contrast, EPR contributed on average only 3.7% of the total production rate. Our estimate of the production of C. sinicus can be applied for potential comparisons of region-specific copepod production.
为了阐明中国东海北部(包括朝鲜南部海域)春季桡足类黄鳝(Calanus sinicus)的作用，我们对黄鳝(Calanus sinicus)的产量进行了估算，包括桡足类第1期(CI)至桡足类第5期(CV)的体产量和成虫产卵量。为了估计桡足动物的体细胞产量，使用了广播公司的经验方程(Hirst & Bunker 2003)。黄颡鱼种群总生物量(雄性和雌性)为0.11 ~ 30.23 mg C m−3，平均为8.69 mg C m−3。在船上孵育24 h后，成虫产卵率(EPR)为0 ~ 14.9个雌卵(平均5.8个雌卵)，相当于平均33.6 μ C m−3 day−1。雌成虫体重比EPR (WSEPR)平均为0.023 d−1，随5 m水深温度和表面叶绿素a浓度的升高而显著升高。WSEPR随个体体重的增加而降低。sinicus种群的总产量为0.02 ~ 3.67 mg C m−3 day−1(平均为0.91 mg C m−3 day−1)，深度综合的平均总产量为52.72 mg C m−2 day−1。CV产量占总产量的54%。相比之下，EPR平均只占总产量的3.7%。我们对黄曲霉产量的估计可以用于区域特定桡足类产量的潜在比较。
{"title":"Estimation of production of the copepod Calanus sinicus during spring in the northern East China Sea","authors":"Hyung-Ku Kang, Cheolsoo Kim","doi":"10.3800/PBR.16.1","DOIUrl":"https://doi.org/10.3800/PBR.16.1","url":null,"abstract":"We estimated the production of the copepod Calanus sinicus, including somatic production of copepodite stage 1 (CI) to copepodite stage 5 (CV) and egg production of adult females, to elucidate the role of C. sinicus during spring in the northern East China Sea, including the southern waters of Korea. To estimate the somatic production of the copepodites, an empirical equation for broadcasters (Hirst & Bunker 2003) was used. The total biomass of the C. sinicus population, including CI to adult males and females, ranged from 0.11 to 30.23 mg C m−3, with a mean of 8.69 mg C m−3. The egg production rate (EPR) of adult females of C. sinicus, measured over 24 h of shipboard incubation, ranged from 0 to 14.9 eggs female−1 day−1 (mean 5.8 eggs female−1 day−1), equivalent to mean 33.6 μg C m−3 day−1. The weight-specific EPR (WSEPR) of adult females averaged 0.023 day−1, and significantly increased with increasing water temperature at 5 m depth and surface chlorophyll a concentration, respectively. WSEPR decreased with increasing body mass of individual adult females. The total production of the C. sinicus population ranged from 0.02 to 3.67 mg C m−3 day−1 (mean 0.91 mg C m−3 day−1) and the depth-integrated mean total production was estimated to be 52.72 mg C m−2 day−1. CV production accounted for 54% of the total production. By contrast, EPR contributed on average only 3.7% of the total production rate. Our estimate of the production of C. sinicus can be applied for potential comparisons of region-specific copepod production.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48372474","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}
Y. Dzhurtubaev, V. Zamorov, M. Dzhurtubaev, N. Shadrin, V. Yakovenko
Species composition and quantitative characteristics of the macrozoobenthos in the Kytai Lake were studied. During 2006–2012, 272 macrozoobenthic samples were collected from the littoral and sublittoral zones of the lake. A total of 66 species were identified in the collected samples. In 2006–2009, the number of species increased from the upper to the lower reaches of the lake, with all 66 species recorded in the latter. However, with increasing salinity and decreasing dissolved oxygen content, the total number of macrozoobenthic species dropped up to 12 in 2012, with the highest number observed at the lower reaches. The average annual macrozoobenthic abundance and biomass in the littoral zone (836±33.08 ind. m−2 and 19.7±0.78 g m−2, respectively) were comparable to those in the sublittoral zone (879±35.16 ind. m−2 and 9.19±0.36 g m−2, respectively). In summer 2012, during the period of maximum development, the macrozoobenthic abundance and biomass in the littoral zone were 346 ind. m−2 and 3.26 g m−2, respectively. The Shannon-Weaver diversity index reached 3.26 bits ind−1 in the littoral zone in 2006–2008 and then decreased to 2.34 bits ind−1 in 2010–2012. The Pielou evenness indices during these periods were 0.66 and 0.61, respectively. In August 2009–2012, the correlation coefficient between salinity and macrozoobenthic abundance was −0.97. In July 2006– 2012, the correlation coefficient between dissolved oxygen content and macrozoobenthic biomass was 0.89, whereas that between dissolved oxygen content and macrozoobenthic species number was 0.95. Results of the correlation and multiple regression analyses revealed the key role of oxygen depletion in decreasing the macrozoobenthic species richness and its development. Principal component analysis indicated that the first two principal components, related to transparency, oxygen, salinity, and temperature, explained most of the total variance of the data. Transparency, oxygen, and temperature positively influenced the macrozoobenthic species composition and quantitative characteristics, whereas salinity exerted a negative influence.
研究了Kytai湖大型底栖动物的种类组成和数量特征。在2006年至2012年期间，从该湖的沿岸和海底带采集了272个大型底栖动物样本。在采集的样本中共鉴定出66个物种。在2006–2009年，物种数量从上游增加到下游，所有66种物种都记录在下游。然而，随着盐度的增加和溶解氧含量的降低，2012年大型底栖动物物种的总数下降到12种，其中下游的数量最多。滨海带的年平均大型底栖动物丰度和生物量（分别为836±33.08 ind.m−2和19.7±0.78 g m−2）与海底亚带的（分别为879±35.16 ind.m–2和9.19±0.36 g m–2）相当。2012年夏季，在最大发育期，沿岸带的大型底栖动物丰度和生物量分别为346 ind.m−2和3.26 g m−2。2006–2008年，Shannon Weaver多样性指数在沿海地区达到3.26位ind−1，然后在2010–2012年降至2.34位ind–1。这些时期的Pielou均匀度指数分别为0.66和0.61。2009-2012年8月，盐度与大型底栖动物丰度之间的相关系数为-0.97。2006–2012年7月，溶解氧含量与大型底栖动物生物量的相关系数为0.89，而溶解氧含量和大型底栖动物物种数量的相关系数则为0.95。相关和多元回归分析结果揭示了缺氧在降低大型底栖动物物种丰富度及其发育中的关键作用。主成分分析表明，与透明度、氧气、盐度和温度有关的前两个主成分解释了数据的大部分总方差。透明度、氧气和温度对大型底栖动物物种的组成和数量特征有积极影响，而盐度则有负面影响。
{"title":"Long-term dynamics of the macrozoobenthos in the Kytai Lake (Danube River, Odessa region, Ukraine)","authors":"Y. Dzhurtubaev, V. Zamorov, M. Dzhurtubaev, N. Shadrin, V. Yakovenko","doi":"10.3800/PBR.16.11","DOIUrl":"https://doi.org/10.3800/PBR.16.11","url":null,"abstract":"Species composition and quantitative characteristics of the macrozoobenthos in the Kytai Lake were studied. During 2006–2012, 272 macrozoobenthic samples were collected from the littoral and sublittoral zones of the lake. A total of 66 species were identified in the collected samples. In 2006–2009, the number of species increased from the upper to the lower reaches of the lake, with all 66 species recorded in the latter. However, with increasing salinity and decreasing dissolved oxygen content, the total number of macrozoobenthic species dropped up to 12 in 2012, with the highest number observed at the lower reaches. The average annual macrozoobenthic abundance and biomass in the littoral zone (836±33.08 ind. m−2 and 19.7±0.78 g m−2, respectively) were comparable to those in the sublittoral zone (879±35.16 ind. m−2 and 9.19±0.36 g m−2, respectively). In summer 2012, during the period of maximum development, the macrozoobenthic abundance and biomass in the littoral zone were 346 ind. m−2 and 3.26 g m−2, respectively. The Shannon-Weaver diversity index reached 3.26 bits ind−1 in the littoral zone in 2006–2008 and then decreased to 2.34 bits ind−1 in 2010–2012. The Pielou evenness indices during these periods were 0.66 and 0.61, respectively. In August 2009–2012, the correlation coefficient between salinity and macrozoobenthic abundance was −0.97. In July 2006– 2012, the correlation coefficient between dissolved oxygen content and macrozoobenthic biomass was 0.89, whereas that between dissolved oxygen content and macrozoobenthic species number was 0.95. Results of the correlation and multiple regression analyses revealed the key role of oxygen depletion in decreasing the macrozoobenthic species richness and its development. Principal component analysis indicated that the first two principal components, related to transparency, oxygen, salinity, and temperature, explained most of the total variance of the data. Transparency, oxygen, and temperature positively influenced the macrozoobenthic species composition and quantitative characteristics, whereas salinity exerted a negative influence.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42443360","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}
V. Segura, Ricardo I. Silva, M. L. Clara, P. Martos, E. Cozzolino, V. Lutz
: The San Jorge Gulf, and the littoral to its north, is one of the most important fishing grounds for Argentina. Nevertheless, phytoplankton production has been scarcely studied. Here we analyzed during spring (2008) and summer (2009) the phytoplankton biomass, production, and the composition of phytoplankton and protozooplankton; their pos sible trophic relationships, and physical conditioners. At the south coast of the gulf during spring micro-nano-plankton (diatoms and dinoflagellates) were predominant and responsible for the maximum integrated production, comparable to that reported for the rich Argentinian shelf-break. Part of the organic carbon produced there was consumed by hetero trophic dinoflagellates, adding a trophic level to the food web. While at the center of the gulf, a conspicuous deep chlo rophyll maximum would probably add organic matter to the bottom. During the following summer (2009), the ultra-fraction represented the largest contribution to total phytoplankton biomass, and was dominated by Synechococcus sp. This, plus the abundance of ciliates, indicate the prevalence of a microbial food web during summer. It has been found that the frontal zones in the north and south of the gulf, favoring high phytoplankton biomass and its maintenance due to high primary production, provide a favorable food environment for impregnated female shrimp in spring, and for lar vae during summer.
{"title":"Primary production and plankton assemblages in the fisheries ground around San Jorge Gulf (Patagonia) during spring and summer","authors":"V. Segura, Ricardo I. Silva, M. L. Clara, P. Martos, E. Cozzolino, V. Lutz","doi":"10.3800/PBR.16.24","DOIUrl":"https://doi.org/10.3800/PBR.16.24","url":null,"abstract":": The San Jorge Gulf, and the littoral to its north, is one of the most important fishing grounds for Argentina. Nevertheless, phytoplankton production has been scarcely studied. Here we analyzed during spring (2008) and summer (2009) the phytoplankton biomass, production, and the composition of phytoplankton and protozooplankton; their pos sible trophic relationships, and physical conditioners. At the south coast of the gulf during spring micro-nano-plankton (diatoms and dinoflagellates) were predominant and responsible for the maximum integrated production, comparable to that reported for the rich Argentinian shelf-break. Part of the organic carbon produced there was consumed by hetero trophic dinoflagellates, adding a trophic level to the food web. While at the center of the gulf, a conspicuous deep chlo rophyll maximum would probably add organic matter to the bottom. During the following summer (2009), the ultra-fraction represented the largest contribution to total phytoplankton biomass, and was dominated by Synechococcus sp. This, plus the abundance of ciliates, indicate the prevalence of a microbial food web during summer. It has been found that the frontal zones in the north and south of the gulf, favoring high phytoplankton biomass and its maintenance due to high primary production, provide a favorable food environment for impregnated female shrimp in spring, and for lar vae during summer.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42209479","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}
The family Vitrinellidae is a group of tiny marine snails that generally occur in shallow waters of temperate and tropical seas. The biology of most vitrinellid species remains poorly understood. In this study, we report that Circulus cinguliferus (A. Adams, 1850) (Vitrinellidae), distributed widely in the warm shallow waters of the Pacific, inhabit crustacean burrows, including those of the mud shrimp Neaxius acanthus (Strahlaxiidae) and snapping shrimp Alpheus rapax (Alpheidae), in the intertidal and subtidal flats of the Okinawa Islands, southern Japan. They exhibited highly clumped distribution among the host burrows, suggesting that they are attracted by conspecifics. Although the biology of most Circulus species remains unknown, Circulus texanus (D. R. Moore, 1965) is known to inhabit stomatopod burrows in the western Atlantic. Our findings suggest that such a commensal habit may be more widespread in this genus than previously thought.
{"title":"Use of crustacean burrows as habitat by the marine snail Circulus cinguliferus (Gastropoda: Truncatelloidea: Vitrinellidae)","authors":"R. Goto, Taigi Sato","doi":"10.3800/PBR.16.69","DOIUrl":"https://doi.org/10.3800/PBR.16.69","url":null,"abstract":"The family Vitrinellidae is a group of tiny marine snails that generally occur in shallow waters of temperate and tropical seas. The biology of most vitrinellid species remains poorly understood. In this study, we report that Circulus cinguliferus (A. Adams, 1850) (Vitrinellidae), distributed widely in the warm shallow waters of the Pacific, inhabit crustacean burrows, including those of the mud shrimp Neaxius acanthus (Strahlaxiidae) and snapping shrimp Alpheus rapax (Alpheidae), in the intertidal and subtidal flats of the Okinawa Islands, southern Japan. They exhibited highly clumped distribution among the host burrows, suggesting that they are attracted by conspecifics. Although the biology of most Circulus species remains unknown, Circulus texanus (D. R. Moore, 1965) is known to inhabit stomatopod burrows in the western Atlantic. Our findings suggest that such a commensal habit may be more widespread in this genus than previously thought.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45615847","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}
The three currently recognized species comprising the pelagic polystiliferous hoplonemertean genus Protopelagonemertes Brinkmann, 1917 are supposedly distinguishable chiefly with respect to the number of proboscis nerves: 29 (varying from 22 to 30) in P. hubrechti (Brinkmann, 1917); 19–21 (varying from 19 to 22) in P. beebei Coe, 1936; and 36 in P. joculatori Van der Spoel, 1988. A single specimen collected off the Pacific coast of Hokkaido, Japan, herein identified as P. beebei, was found to possess 19–23 primary proboscis nerves. In addition to the primary proboscis nerves, the material also possessed 12–16 secondary proboscis nerves, which are discernible from the primary nerves in that they coexist with putative glial cells. Although secondary proboscis nerves have been identified in some other species in the Pelagica, they have not previously been described for any members of the Protopelagonemertes. Our findings thus prompted us to question the validity of morphological species delimitation within this genus, given that the distinction between primary and secondary proboscis nerves has previously not been taken into consideration. Close examination of the specimen in the living state revealed that it is characterized by a pair of cephalic furrows, a structure commonly found in benthic representatives of the phylum, but herein confirmed for the first time among the Pelagica. A 658-bp partial sequence of the mitochondrial cytochrome c oxidase subunit I gene from the newly examined specimen was found to be identical to sequences derived from two other specimens previously collected in Sagami Bay, thereby indicating that P. beebei may occur commonly in Japanese mesoto bathypelagic waters.
目前公认的三个物种组成了远洋多tilitis hoplonemertean属Protopelagonemertes Brinkmann，1917，主要根据长鼻神经的数量可以区分：P.hubrechti中的29个（从22到30不等）（Brinkman，1917）；19–21（从19到22不等），毕贝科，1936年；P.joculatori Van der Spoel，1988年，第36页。在日本北海道太平洋海岸采集的一个标本，本文鉴定为毕贝P.beebei，被发现拥有19-23条初级长鼻神经。除了初级长鼻神经外，该材料还具有12-16个次级长鼻神经，这些神经与初级神经不同，因为它们与假定的神经胶质细胞共存。尽管在Pelagica的其他一些物种中已经发现了次级长鼻神经，但以前还没有对原Pelagonemertes的任何成员进行过描述。因此，我们的发现促使我们质疑该属形态物种划界的有效性，因为以前没有考虑初级和次级长鼻神经之间的区别。对活体标本的仔细检查表明，它的特征是有一对头沟，这种结构通常在该门的底栖生物代表中发现，但在Pelagica中首次得到证实。来自新检测标本的线粒体细胞色素c氧化酶亚基I基因的658 bp部分序列被发现与之前在相模湾采集的另外两个标本的序列相同，从而表明山毛榉可能常见于日本中深海水域。
{"title":"A morphological note on the pelagic polystiliferous hoplonemertean Protopelagonemertes beebei (Nemertea: Pelagica)","authors":"H. Kajihara, A. Yamaguchi","doi":"10.3800/pbr.15.337","DOIUrl":"https://doi.org/10.3800/pbr.15.337","url":null,"abstract":"The three currently recognized species comprising the pelagic polystiliferous hoplonemertean genus Protopelagonemertes Brinkmann, 1917 are supposedly distinguishable chiefly with respect to the number of proboscis nerves: 29 (varying from 22 to 30) in P. hubrechti (Brinkmann, 1917); 19–21 (varying from 19 to 22) in P. beebei Coe, 1936; and 36 in P. joculatori Van der Spoel, 1988. A single specimen collected off the Pacific coast of Hokkaido, Japan, herein identified as P. beebei, was found to possess 19–23 primary proboscis nerves. In addition to the primary proboscis nerves, the material also possessed 12–16 secondary proboscis nerves, which are discernible from the primary nerves in that they coexist with putative glial cells. Although secondary proboscis nerves have been identified in some other species in the Pelagica, they have not previously been described for any members of the Protopelagonemertes. Our findings thus prompted us to question the validity of morphological species delimitation within this genus, given that the distinction between primary and secondary proboscis nerves has previously not been taken into consideration. Close examination of the specimen in the living state revealed that it is characterized by a pair of cephalic furrows, a structure commonly found in benthic representatives of the phylum, but herein confirmed for the first time among the Pelagica. A 658-bp partial sequence of the mitochondrial cytochrome c oxidase subunit I gene from the newly examined specimen was found to be identical to sequences derived from two other specimens previously collected in Sagami Bay, thereby indicating that P. beebei may occur commonly in Japanese mesoto bathypelagic waters.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46356553","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}
: The Polynoidae, commonly known as “scale-worms” due to the scale-like elytra on the dorsal surface, contains many species living in symbioses with other invertebrates. Most of these symbionts are host-specific, but some have a wide range of hosts. The genus Asterophilia includes two species living in shallow subtropical to tropical waters in the Pacific Ocean as ectosymbionts of asteroids and, more rarely, crinoids. Here, we recorded Asterophilia culcitae from asteroid hosts ( Culcita novaeguineae , Linckia laevigata , L. guildingi , and Leiaster leachi ) and, for the first time, from holothurian hosts [ Stichopus chloronotus , Holothuria atra , H. ( Stauropora ) pervicax , and Bohadschia argus ] along warm Japanese Pacific coasts. The cytochrome c oxidase subunit I sequences of the specimens from holothurians did not differ significantly from those on asteroid hosts, proving that A. culcitae has a wide host range across three dif-ferent echinoderm classes: asteroids, holothurians, and crinoids. The general body color of A. culcitae was constantly reddish (female) or whitish (male), regardless of the host body color, although a previous study suggested that it differs in accordance with the host body color. However, we found that one individual from a holothurian host showed a dif-ferent color pattern: A. culcitae typically shows three whitish or yellowish elytral mounds that have been suggested to mimic the tube foot of the asteroid hosts, whereas one individual from S. chloronotus had reddish brown translucent mounds, which we suggest might be cryptic on its holothurian host.
{"title":"Widening the host range of the ectosymbiotic scale-worm Asterophilia culcitae (Annelida: Polynoidae) to three echinoderm classes, with data on its body color variation","authors":"Takahiro Sugiyama, Naoto Jimi, R. Goto","doi":"10.3800/pbr.15.289","DOIUrl":"https://doi.org/10.3800/pbr.15.289","url":null,"abstract":": The Polynoidae, commonly known as “scale-worms” due to the scale-like elytra on the dorsal surface, contains many species living in symbioses with other invertebrates. Most of these symbionts are host-specific, but some have a wide range of hosts. The genus Asterophilia includes two species living in shallow subtropical to tropical waters in the Pacific Ocean as ectosymbionts of asteroids and, more rarely, crinoids. Here, we recorded Asterophilia culcitae from asteroid hosts ( Culcita novaeguineae , Linckia laevigata , L. guildingi , and Leiaster leachi ) and, for the first time, from holothurian hosts [ Stichopus chloronotus , Holothuria atra , H. ( Stauropora ) pervicax , and Bohadschia argus ] along warm Japanese Pacific coasts. The cytochrome c oxidase subunit I sequences of the specimens from holothurians did not differ significantly from those on asteroid hosts, proving that A. culcitae has a wide host range across three dif-ferent echinoderm classes: asteroids, holothurians, and crinoids. The general body color of A. culcitae was constantly reddish (female) or whitish (male), regardless of the host body color, although a previous study suggested that it differs in accordance with the host body color. However, we found that one individual from a holothurian host showed a dif-ferent color pattern: A. culcitae typically shows three whitish or yellowish elytral mounds that have been suggested to mimic the tube foot of the asteroid hosts, whereas one individual from S. chloronotus had reddish brown translucent mounds, which we suggest might be cryptic on its holothurian host.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45507006","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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