Justus O. Omweri, Keita W. Suzuki, Shouji Houki, E. Lavergne, H. Inoue, H. Yokoyama, Y. Yamashita
The euryhaline mysid Neomysis awatschensis occurs widely in estuaries and brackish lakes in Japan. Although N. awatschensis may serve as an essential energy channel to higher trophic levels, its feeding ecology has been studied only in sheltered and desalinated Lake Kasumigaura. To determine major food sources for N. awatschensis, monthly sampling was conducted during the day along the microtidal Yura River estuary from March 2014 to July 2015. Additional sampling was conducted in May 2019 to assess diel vertical migration in relation to feeding. Microscopic examinations revealed that benthic diatoms (e.g. Bacillaria paxillifer and Navicula spp.) dominated in the stomach irrespective of developmental stage, diel cycle, or season. Stable carbon and nitrogen isotope ratios in N. awatschensis and its potential food sources indicated great contributions to the diet of N. awatschensis from benthic microalgae (mainly benthic diatoms) in 2014 and from particulate organic matter (mainly phytoplankton) in 2015. Although N. awatschensis always concentrated close to the bottom in 2019, diel vertical migration might have happened in 2015, when fresh water occupied the whole estuary possibly due to river mouth clogging. Under the stagnant and oligohaline conditions, N. awatschensis could have swum up into the water column and fed on phytoplankton at night in 2015. This hypothesis may resolve the apparent contradiction between the microscopy and stable isotope analysis in 2015. In the Yura River estuary, N. awatschensis feeds primarily on benthic diatoms, although it can utilize phytoplankton flexibly in response to prevailing environmental conditions.
{"title":"Flexible herbivory of the euryhaline mysid Neomysis awatschensis in the microtidal Yura River estuary, central Japan","authors":"Justus O. Omweri, Keita W. Suzuki, Shouji Houki, E. Lavergne, H. Inoue, H. Yokoyama, Y. Yamashita","doi":"10.3800/pbr.16.278","DOIUrl":"https://doi.org/10.3800/pbr.16.278","url":null,"abstract":"The euryhaline mysid Neomysis awatschensis occurs widely in estuaries and brackish lakes in Japan. Although N. awatschensis may serve as an essential energy channel to higher trophic levels, its feeding ecology has been studied only in sheltered and desalinated Lake Kasumigaura. To determine major food sources for N. awatschensis, monthly sampling was conducted during the day along the microtidal Yura River estuary from March 2014 to July 2015. Additional sampling was conducted in May 2019 to assess diel vertical migration in relation to feeding. Microscopic examinations revealed that benthic diatoms (e.g. Bacillaria paxillifer and Navicula spp.) dominated in the stomach irrespective of developmental stage, diel cycle, or season. Stable carbon and nitrogen isotope ratios in N. awatschensis and its potential food sources indicated great contributions to the diet of N. awatschensis from benthic microalgae (mainly benthic diatoms) in 2014 and from particulate organic matter (mainly phytoplankton) in 2015. Although N. awatschensis always concentrated close to the bottom in 2019, diel vertical migration might have happened in 2015, when fresh water occupied the whole estuary possibly due to river mouth clogging. Under the stagnant and oligohaline conditions, N. awatschensis could have swum up into the water column and fed on phytoplankton at night in 2015. This hypothesis may resolve the apparent contradiction between the microscopy and stable isotope analysis in 2015. In the Yura River estuary, N. awatschensis feeds primarily on benthic diatoms, although it can utilize phytoplankton flexibly in response to prevailing environmental conditions.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44005648","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}
A. Iida, K. Nohara, F. Yusoff, Khwanruan Srinui, T. M. Ha, S. Ohtsuka, E. Metillo, Honorio B. Pagliawan, J. Nishikawa
The rhizostome jellyfishes, Rhopilema hispidum and Lobonemoides robustus, are two of the most abundant and commercially important species in Southeast Asia. However, information on genetic diversity and continuities among local populations remains totally unknown. We explored the genetic structure and population continuities of R. hispidum and L. robustus using genetic markers (COI & ITS1 regions) at 11 locations in four countries in Southeast Asia where fisheries were conducted. Rhopilema populations showed genetic distances (ΦST) among locations correlated positively with geographic distances, suggesting that they are in the isolation-by-distance (IBD). In Lobonemoides, molecular analysis revealed three distinct clades corresponding to sampling locations. Genetic distances among locations in L. robustus suggested that all populations maintain significant isolation. Our study reveals that these two blooming species have different phylogeographic patterns and differ in genetic diversity and continuities. Eustatic sea level changes during the Pleistocene and present ocean current systems, as well as differences in biological characteristics of these two species may explain these phylogeographic differences. Our results also suggest that jellyfish fisheries need to be carefully managed to avoid extinction of local populations and maintain the genetic diversity of these species, especially for L. robustus, which exhibits considerable genetic diversity in each location.
{"title":"Genetic diversities of commercially harvested jellyfish, Rhopilema hispidum and Lobonemoides robustus in Southeast Asia","authors":"A. Iida, K. Nohara, F. Yusoff, Khwanruan Srinui, T. M. Ha, S. Ohtsuka, E. Metillo, Honorio B. Pagliawan, J. Nishikawa","doi":"10.3800/pbr.16.308","DOIUrl":"https://doi.org/10.3800/pbr.16.308","url":null,"abstract":"The rhizostome jellyfishes, Rhopilema hispidum and Lobonemoides robustus, are two of the most abundant and commercially important species in Southeast Asia. However, information on genetic diversity and continuities among local populations remains totally unknown. We explored the genetic structure and population continuities of R. hispidum and L. robustus using genetic markers (COI & ITS1 regions) at 11 locations in four countries in Southeast Asia where fisheries were conducted. Rhopilema populations showed genetic distances (ΦST) among locations correlated positively with geographic distances, suggesting that they are in the isolation-by-distance (IBD). In Lobonemoides, molecular analysis revealed three distinct clades corresponding to sampling locations. Genetic distances among locations in L. robustus suggested that all populations maintain significant isolation. Our study reveals that these two blooming species have different phylogeographic patterns and differ in genetic diversity and continuities. Eustatic sea level changes during the Pleistocene and present ocean current systems, as well as differences in biological characteristics of these two species may explain these phylogeographic differences. Our results also suggest that jellyfish fisheries need to be carefully managed to avoid extinction of local populations and maintain the genetic diversity of these species, especially for L. robustus, which exhibits considerable genetic diversity in each location.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42672776","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}
: Juvenile Japanese Neptune whelk Neptunea arthritica preys on small gastropods in the field. Although the most common prey is Homalopoma sangarense , its density is lower than those of other prey species (e.g., Barleeia angustata , Reticunassa fratercula , and Cantharidus japonicus ) in the field. To clarify whether N. arthritica juveniles show an “ actual ” or “ apparent ” preference for H. sangarense , we conducted a single-prey feeding experiment. Although N. arthritica attacked H. sangarense earlier and more frequently than B. angustata and C. japonicus , there was no dif-ference in attack frequency and latency between H. sangarense and R. fratercula . Attacks on H. sangarense failed more frequently than on the other species, and the handling time for H. sangarense was significantly longer compared to the other three species. The large difference in handling time (over 10-fold difference) could be caused by the presence of a thick calcareous operculum on H. sangarense . Eventually, N. arthritica consumed more individuals of R. fratercula than of H. sangarense in the experiment. These results indicate that N. arthritica juveniles exhibit both “ actual ” and “ apparent ” preferences for H. sangarense . The “ actual preference ” of N. arthritica juveniles may reflect the past species compositions of small gastropods, because H. sangarense has been previously reported as the dominant species at the study site.
{"title":"Prey preferences of juvenile whelk Neptunea arthritica (Gastropoda: Buccinidae) in Hakodate Bay, Hokkaido, Japan","authors":"Ryusei Yamakami, S. Wada","doi":"10.3800/pbr.16.257","DOIUrl":"https://doi.org/10.3800/pbr.16.257","url":null,"abstract":": Juvenile Japanese Neptune whelk Neptunea arthritica preys on small gastropods in the field. Although the most common prey is Homalopoma sangarense , its density is lower than those of other prey species (e.g., Barleeia angustata , Reticunassa fratercula , and Cantharidus japonicus ) in the field. To clarify whether N. arthritica juveniles show an “ actual ” or “ apparent ” preference for H. sangarense , we conducted a single-prey feeding experiment. Although N. arthritica attacked H. sangarense earlier and more frequently than B. angustata and C. japonicus , there was no dif-ference in attack frequency and latency between H. sangarense and R. fratercula . Attacks on H. sangarense failed more frequently than on the other species, and the handling time for H. sangarense was significantly longer compared to the other three species. The large difference in handling time (over 10-fold difference) could be caused by the presence of a thick calcareous operculum on H. sangarense . Eventually, N. arthritica consumed more individuals of R. fratercula than of H. sangarense in the experiment. These results indicate that N. arthritica juveniles exhibit both “ actual ” and “ apparent ” preferences for H. sangarense . The “ actual preference ” of N. arthritica juveniles may reflect the past species compositions of small gastropods, because H. sangarense has been previously reported as the dominant species at the study site.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48109359","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}
Hisanori Kohtsuka, K. Oguchi, Y. Yamana, M. Okanishi
: More than 100 individuals of sea cucumber larvae were collected in the Japanese coastal sea of Moroiso, Sagami Bay, Kanagawa Prefecture, central-eastern Japan, in January 2018. Based on an obtained sequence of mitochondrial 16S rRNA gene region of one juvenile, it was identified as Sclerodactyla multipes by BLAST search with 0.3% genetic distance. The developmental process of the S. multipes was observed for three months, in which time, they grew from 250 µ m to about 4 mm in length; here they showed distinct tentacles and dermal ossicles. Detailed morphological features of this species were described based on stereomicroscopic, fluorescence and SEM observations for the first time. This is the first description of life history through planktonic larva to juveniles in the family Sclerodactylidae.
{"title":"First description of developmental processes in Sclerodactyla multipes (Echinodermata: Holothuroidea: Dendrochirotida) from Misaki, Sagami Bay, Japan","authors":"Hisanori Kohtsuka, K. Oguchi, Y. Yamana, M. Okanishi","doi":"10.3800/pbr.16.228","DOIUrl":"https://doi.org/10.3800/pbr.16.228","url":null,"abstract":": More than 100 individuals of sea cucumber larvae were collected in the Japanese coastal sea of Moroiso, Sagami Bay, Kanagawa Prefecture, central-eastern Japan, in January 2018. Based on an obtained sequence of mitochondrial 16S rRNA gene region of one juvenile, it was identified as Sclerodactyla multipes by BLAST search with 0.3% genetic distance. The developmental process of the S. multipes was observed for three months, in which time, they grew from 250 µ m to about 4 mm in length; here they showed distinct tentacles and dermal ossicles. Detailed morphological features of this species were described based on stereomicroscopic, fluorescence and SEM observations for the first time. This is the first description of life history through planktonic larva to juveniles in the family Sclerodactylidae.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43359540","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}
Mastigias papua, known as the golden (or spotted) jellyfish, is an epipelagic jellyfish widely distributed in the warm waters of the West Pacific. This jellyfish has a brownish body, owing to zooxanthellae, and white spots. We measured the maximum force to pierce the umbrella, which averaged 94–144 mm in diameter, to evaluate the hardness of M. papua, and returned a range of 0.14–0.45 N. Correlation analyses indicate that when the M. papua medusa grows (i.e., becomes heavier), the umbrella becomes larger in diameter, as well as thicker and harder within the size range we examined. However, a significant relationship between the hardness of the umbrellar apex and the thickness of the umbrella was not obtained. White spots are comprised of loose aggregates of mesogleal cells containing reflective granules. Since the white spots and the transparent parts were not significantly different in hardness, the spots were unlikely to strengthen the umbrella. The primary function of the spots may be the shading of solar radiation. Most of the zooxanthellae are located in mesogleal cells, and often beneath the exumbrellar epidermis. Therefore, light shading by white spots may be unnecessary for the zooxanthellae in mesogleal cells.
{"title":"Umbrella of Mastigias papua (Scyphozoa: Rhizostomeae: Mastigiidae): hardness and cytomorphology with remarks on colors","authors":"Yuki Hamaguchi, A. Iida, J. Nishikawa, E. Hirose","doi":"10.3800/pbr.16.221","DOIUrl":"https://doi.org/10.3800/pbr.16.221","url":null,"abstract":"Mastigias papua, known as the golden (or spotted) jellyfish, is an epipelagic jellyfish widely distributed in the warm waters of the West Pacific. This jellyfish has a brownish body, owing to zooxanthellae, and white spots. We measured the maximum force to pierce the umbrella, which averaged 94–144 mm in diameter, to evaluate the hardness of M. papua, and returned a range of 0.14–0.45 N. Correlation analyses indicate that when the M. papua medusa grows (i.e., becomes heavier), the umbrella becomes larger in diameter, as well as thicker and harder within the size range we examined. However, a significant relationship between the hardness of the umbrellar apex and the thickness of the umbrella was not obtained. White spots are comprised of loose aggregates of mesogleal cells containing reflective granules. Since the white spots and the transparent parts were not significantly different in hardness, the spots were unlikely to strengthen the umbrella. The primary function of the spots may be the shading of solar radiation. Most of the zooxanthellae are located in mesogleal cells, and often beneath the exumbrellar epidermis. Therefore, light shading by white spots may be unnecessary for the zooxanthellae in mesogleal cells.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43235570","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}
: Ikeda taenioides (Ikeda, 1904) (Annelida: Thalassematidae: Bonelliinae) is the world ʼ s longest spoon worm species, which possesses an extremely long tape-like proboscis with a striped color pattern and a large brownish red trunk. This species is endemic to the Japanese Islands and inhabits a deep vertical burrow in intertidal and subtidal sand flats. Their proboscis, which extends from its small burrow opening, has been frequently observed around Japanese coasts. However, sampling of the main body (i.e., trunk) has been extremely rare because it always stays within a deep part of the burrow. Here, we report the success of the sampling of two specimens of I. taenioides with trunks in two different localities of the Seto Inland Sea (i.e., Ohmishima and Hachi), Japan, in 2019 and 2020 using a yabby pump. This is the first sampling of the trunk of I. taenioides in 88 years after its last collection in Onomichi Bay in 1931. We described the trunk color and morphological characteristics of the two specimens, including the internal anatomy. The trunks of the two specimens showed different colors, that is, pale brown (Ohmishima) and deep brownish red (Hachi). However, they were not distinguished to the species level by the comparison of partial COI sequences, suggesting that I. taenioides has an intraspecific variation in trunk color. Despite the difference in the sampling seasons (Ohmishima: June, Hachi: February), both specimens included numerous ripe eggs. According to previous studies, those collected in November and December also included numerous ripe eggs. Taken together, I. taenioides may be reproductive throughout the year or have multiple reproductive seasons per year.
{"title":"Giant spoon worms pumped out of their deep burrows: First collection of the main bodies of Ikeda taenioides (Annelida: Thalassematidae: Bonelliinae) in 88 years","authors":"R. Goto, Yumi Henmi, Y. Shiozaki, G. Itani","doi":"10.3800/pbr.16.155","DOIUrl":"https://doi.org/10.3800/pbr.16.155","url":null,"abstract":": Ikeda taenioides (Ikeda, 1904) (Annelida: Thalassematidae: Bonelliinae) is the world ʼ s longest spoon worm species, which possesses an extremely long tape-like proboscis with a striped color pattern and a large brownish red trunk. This species is endemic to the Japanese Islands and inhabits a deep vertical burrow in intertidal and subtidal sand flats. Their proboscis, which extends from its small burrow opening, has been frequently observed around Japanese coasts. However, sampling of the main body (i.e., trunk) has been extremely rare because it always stays within a deep part of the burrow. Here, we report the success of the sampling of two specimens of I. taenioides with trunks in two different localities of the Seto Inland Sea (i.e., Ohmishima and Hachi), Japan, in 2019 and 2020 using a yabby pump. This is the first sampling of the trunk of I. taenioides in 88 years after its last collection in Onomichi Bay in 1931. We described the trunk color and morphological characteristics of the two specimens, including the internal anatomy. The trunks of the two specimens showed different colors, that is, pale brown (Ohmishima) and deep brownish red (Hachi). However, they were not distinguished to the species level by the comparison of partial COI sequences, suggesting that I. taenioides has an intraspecific variation in trunk color. Despite the difference in the sampling seasons (Ohmishima: June, Hachi: February), both specimens included numerous ripe eggs. According to previous studies, those collected in November and December also included numerous ripe eggs. Taken together, I. taenioides may be reproductive throughout the year or have multiple reproductive seasons per year.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48508498","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}
Xiaodong Wang, Yuta Yagi, Shotaro Tojima, I. Kinoshita, Y. Hirota, S. Fujita
: The ontogeny of Ilisha elongata was reviewed, and their early distribution was examined because information on the early life history of this species is limited. Revision in ontogeny revealed several unique characteristics to this species, such as two chorions in the egg and a more anterior pelvic bud (fin) position. These characteristics contrast strikingly with the clupeid fishes, suggesting that this species belongs to the Pristigasteridae and not to the Clupeidae. Data from ichthyoplankton collected in March, May, July and November suggest that I. elongata spawned just off river mouths in summer and attained peak spawning in June. The larvae with elliptical eyes migrated inside the rivers, where the waters were more turbid. Thus, the spawning and nursery grounds of I. elongata almost entirely overlapped with those of the clupeid Sardinella zunasi both temporally and spatially, which may result in larval competition between the two species.
{"title":"Early life history of Ilisha elongata (Pristigasteridae, Clupeiformes, Pisces) in Ariake Sound, Shimabara Bay, Japan","authors":"Xiaodong Wang, Yuta Yagi, Shotaro Tojima, I. Kinoshita, Y. Hirota, S. Fujita","doi":"10.3800/pbr.16.210","DOIUrl":"https://doi.org/10.3800/pbr.16.210","url":null,"abstract":": The ontogeny of Ilisha elongata was reviewed, and their early distribution was examined because information on the early life history of this species is limited. Revision in ontogeny revealed several unique characteristics to this species, such as two chorions in the egg and a more anterior pelvic bud (fin) position. These characteristics contrast strikingly with the clupeid fishes, suggesting that this species belongs to the Pristigasteridae and not to the Clupeidae. Data from ichthyoplankton collected in March, May, July and November suggest that I. elongata spawned just off river mouths in summer and attained peak spawning in June. The larvae with elliptical eyes migrated inside the rivers, where the waters were more turbid. Thus, the spawning and nursery grounds of I. elongata almost entirely overlapped with those of the clupeid Sardinella zunasi both temporally and spatially, which may result in larval competition between the two species.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41908085","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}
Wen Liu, Hiroshi Kamitakahara, S. Maegawa, H. Toyohara
: Carbohydrate-binding modules (CBMs) are non-catalytic protein domains that bind to carbohydrates, and have been well studied in microorganisms. Endogenous CBMs in aquatic invertebrates, however, have not yet been identified, and little is known about their ecological significance to wetland environments. Using an approach of characterizing a recombinant CBM ( Cj Cel9A) from a brackish bivalve, Corbicula japonica , this work identified Cj Cel9A-CBM ʼ s cellulose-binding activity. Scatchard plot analysis in the study of Cj Cel9A-CBM binding to α -cellulose showed a high corresponding partitioning coefficient (K r ) of 20.33, indicating Cj Cel9A-CBM ʼ s high affinity for cellulose. In addition, this affinity tolerated a high ion concentration buffer system, consistent with C. japonica ʼ s adaption to brackish wetland environments. Moreover, immuno-scanning electron microscopy (immuno-SEM) suggested that Cj Cel9A-CBM binds to α -cellulose unevenly, which was further determined to be caused by its higher affinity for crystalline cellulose (Cellulose I, mostly seen in plant leaves). Together, these findings suggest that Cj Cel9A-CBM is capable of immobilizing its associated catalytic domain on environmental crystalline cellulose (i.e., fallen leaves) in wetland sediments. Most importantly, they could provide a reasonable answer to a question recognized broadly in wetland ecologists, namely, why many wetland sediments have constant cellulase activities, although the sediments are being washed almost every day.
{"title":"Aquatic invertebrate’s Carbohydrate-binding module assists environmental cellulase to immobilize in wetland sediments","authors":"Wen Liu, Hiroshi Kamitakahara, S. Maegawa, H. Toyohara","doi":"10.3800/pbr.16.191","DOIUrl":"https://doi.org/10.3800/pbr.16.191","url":null,"abstract":": Carbohydrate-binding modules (CBMs) are non-catalytic protein domains that bind to carbohydrates, and have been well studied in microorganisms. Endogenous CBMs in aquatic invertebrates, however, have not yet been identified, and little is known about their ecological significance to wetland environments. Using an approach of characterizing a recombinant CBM ( Cj Cel9A) from a brackish bivalve, Corbicula japonica , this work identified Cj Cel9A-CBM ʼ s cellulose-binding activity. Scatchard plot analysis in the study of Cj Cel9A-CBM binding to α -cellulose showed a high corresponding partitioning coefficient (K r ) of 20.33, indicating Cj Cel9A-CBM ʼ s high affinity for cellulose. In addition, this affinity tolerated a high ion concentration buffer system, consistent with C. japonica ʼ s adaption to brackish wetland environments. Moreover, immuno-scanning electron microscopy (immuno-SEM) suggested that Cj Cel9A-CBM binds to α -cellulose unevenly, which was further determined to be caused by its higher affinity for crystalline cellulose (Cellulose I, mostly seen in plant leaves). Together, these findings suggest that Cj Cel9A-CBM is capable of immobilizing its associated catalytic domain on environmental crystalline cellulose (i.e., fallen leaves) in wetland sediments. Most importantly, they could provide a reasonable answer to a question recognized broadly in wetland ecologists, namely, why many wetland sediments have constant cellulase activities, although the sediments are being washed almost every day.","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46627276","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}
Kenjiro Hinode, Hoshimi Kamisaki, Gregory N. Nishihara, Ryuta Terada
We present a descriptive account of the dynamics of epiphytic diatoms, epifauna, and the leaf surface area of Zostera marina in a shallow water ecosystem. We hypothesized that the growth stage of the host macrophyte (i.e., leaf surface area) influenced the presence of epiflora and epifauna, as well as that the leaf surface area and epifaunal population density affected the cell density and species composition of epiphytic diatoms. To evaluate this hypothesis, we quantified the leaf surface area of a host macrophyte (Zostera marina), the presence of epifauna, and the community of epiphytic diatoms that could be observed on the leaves of Z. marina during the period from May 2017 to December 2018. We conducted a descriptive analysis of the time-series observations of leaf surface area, epiphytic diatom density, and epifauna population density. Epiphytic diatom density was low and epifauna density was high during the growing season of Z. marina. Epiphytic diatom density was high and epifauna density was low during the maturation and senescence periods of Z. marina. Our analysis shows that epifauna densities lagged epiflora densities by at least four months, and that epiflora densities lagged leaf area by four months. Therefore, we hypothesized that herbivorous gastropods and amphipods could alter species composition via their preference of food items (active choice) or by ingesting more of the species that were structurally more available (passive preference).
{"title":"The phenology of epiphytic diatoms and epifauna observed on Zostera marina of Arikawa Bay, Nagasaki Prefecture, Japan","authors":"Kenjiro Hinode, Hoshimi Kamisaki, Gregory N. Nishihara, Ryuta Terada","doi":"10.3800/pbr.16.179","DOIUrl":"https://doi.org/10.3800/pbr.16.179","url":null,"abstract":"We present a descriptive account of the dynamics of epiphytic diatoms, epifauna, and the leaf surface area of Zostera marina in a shallow water ecosystem. We hypothesized that the growth stage of the host macrophyte (i.e., leaf surface area) influenced the presence of epiflora and epifauna, as well as that the leaf surface area and epifaunal population density affected the cell density and species composition of epiphytic diatoms. To evaluate this hypothesis, we quantified the leaf surface area of a host macrophyte (Zostera marina), the presence of epifauna, and the community of epiphytic diatoms that could be observed on the leaves of Z. marina during the period from May 2017 to December 2018. We conducted a descriptive analysis of the time-series observations of leaf surface area, epiphytic diatom density, and epifauna population density. Epiphytic diatom density was low and epifauna density was high during the growing season of Z. marina. Epiphytic diatom density was high and epifauna density was low during the maturation and senescence periods of Z. marina. Our analysis shows that epifauna densities lagged epiflora densities by at least four months, and that epiflora densities lagged leaf area by four months. Therefore, we hypothesized that herbivorous gastropods and amphipods could alter species composition via their preference of food items (active choice) or by ingesting more of the species that were structurally more available (passive preference).","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48910523","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}
Holothurians referred to as “teatfish” contain three species, Holothuria (Microthele) nobilis, H. (M.) whitmaei and H. (M.) fuscogilva, that have recently been included in CITES Appendix II for sustainable catch and trade. Taxonomic key traits of these species are primarily genetic sequences and there are few morphological differences among them, except for color patterns of the body. Although located in the northern limit of their distribution, there have been no reports identifying species of teatfish in Japan based on both morphology and genetic traits. This study investigated sequences of mitochondrial cytochrome oxidase subunit I (COI) and morphology including ossicles of black and white teatfish collected from Okinawa Island and Yaeyama Islands, Japan. The entirely black specimens and white specimens having black mottles on the dorsal side were identified as Holothuria (M.) whitmaei and H. (M.) fuscogilva, respectively, based on the agreement of genetic and morphological traits and with published data. There is no clear difference in COI sequences between specimens from Japan and other Pacific regions for both species. The only inconsistent finding with previous reports was that one specimen of H. (M.) whitmaei lacked Cuvierian tubules, which are usually present in this species, implying plasticity of this trait. Mean diameter of the disc and height of the pillars of table ossicles were shorter and longer, respectively, in H. (M.) fuscogilva than in H. (M.) whitmaei (p<0.05, t-test).
{"title":"Identification of species of teatfish (Holothuroidea: Holothuriida) in Japan based on mitochondrial cytochrome oxidase subunit I (COI) sequences, morphology, and ossicles","authors":"I. Tanita, S. Nishihama, T. Hayashibara","doi":"10.3800/pbr.16.200","DOIUrl":"https://doi.org/10.3800/pbr.16.200","url":null,"abstract":"Holothurians referred to as “teatfish” contain three species, Holothuria (Microthele) nobilis, H. (M.) whitmaei and H. (M.) fuscogilva, that have recently been included in CITES Appendix II for sustainable catch and trade. Taxonomic key traits of these species are primarily genetic sequences and there are few morphological differences among them, except for color patterns of the body. Although located in the northern limit of their distribution, there have been no reports identifying species of teatfish in Japan based on both morphology and genetic traits. This study investigated sequences of mitochondrial cytochrome oxidase subunit I (COI) and morphology including ossicles of black and white teatfish collected from Okinawa Island and Yaeyama Islands, Japan. The entirely black specimens and white specimens having black mottles on the dorsal side were identified as Holothuria (M.) whitmaei and H. (M.) fuscogilva, respectively, based on the agreement of genetic and morphological traits and with published data. There is no clear difference in COI sequences between specimens from Japan and other Pacific regions for both species. The only inconsistent finding with previous reports was that one specimen of H. (M.) whitmaei lacked Cuvierian tubules, which are usually present in this species, implying plasticity of this trait. Mean diameter of the disc and height of the pillars of table ossicles were shorter and longer, respectively, in H. (M.) fuscogilva than in H. (M.) whitmaei (p<0.05, t-test).","PeriodicalId":56054,"journal":{"name":"Plankton & Benthos Research","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48335187","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：