Pub Date : 2024-11-10DOI: 10.1016/j.dsr.2024.104416
Tanja Stratmann , Kathrin Busch , Anna de Kluijver , Michelle Kelly , Sadie Mills , Sven Rossel , Peter J. Schupp
<div><div>Sponges are an important component of deep-water ecosystems enhancing eukaryotic biodiversity by hosting diverse endo- and epibiota and providing three dimensional habitats for benthic invertebrates and fishes. As holobionts they are important hosts of microorganisms which are involved in carbon and nitrogen cycling. While increasing exploration of deep-water habitats results in new sponge species being discovered, little is known about their physiology and role in nutrient fluxes. Around New Zealand (Southwest Pacific), the sponge biodiversity is particularly high, and we selected six deep-sea sponge genera (<em>Saccocalyx</em>, <em>Suberites</em>, <em>Tedania</em>, <em>Halichondria</em>/<em>Dendoricella</em>, <em>Lissodendoryx</em>) and a member of the Sceptrulophora order for <em>in-situ</em> and <em>ex-situ</em> experiments.</div><div>We investigated the biochemical composition of the sponges, measured oxygen consumption and inorganic nutrient fluxes, as well as bacterial and phospholipid-derived fatty acid (PLFA) compositions. Our aim was to assess differences in fluxes and fatty acid composition among sponges and linking their bacterial communities to nitrogen cycling processes.</div><div>All sponges excreted nitrite and ammonia. Nitrate and phosphate excretion were independent of phylum affiliation (Demospongiae, Hexactinellida). Nitrate was excreted by <em>Halichondria</em>/<em>Dendoricella</em> and <em>Lissodendoryx</em>, whereas <em>Suberites</em>, <em>Tedania</em>, and Sceptrulophora consumed it. Phosphate was excreted by Sceptrulophora and <em>Halichondria</em>/<em>Dendoricella</em> and consumed by all other sponges. Oxygen consumption rates ranged from 0.17 to 3.56 ± 0.60 mmol O<sub>2</sub> g C<sup>-1</sup> d<sup>−1</sup>.</div><div>The PLFA composition was very sponge-genera dependent and consisted mostly of long-chain fatty acids. Most PLFAs were sponge-specific, followed by bacteria-specific PLFAs, and others.</div><div>All sponges, except for <em>Suberites</em>, were low-microbial abundance (LMA) sponges whose bacterial community composition was dominated by Proteobacteria, Bacteroidota, Planctomycetota, and Nitrospinota. <em>Suberites</em> consisted of high-microbial abundance (HMA) sponges with Proteobacteria, Chloroflexota, Acidobacteriota, and Actinobacteriota as dominant bacteria.</div><div>Based on the inorganic nitrogen flux measurements, we identified three types of nitrogen cycling in the sponges: In type 1, sponges (<em>Dendoricella</em> spp. indet., <em>Lissodendoryx</em>) respired aerobically and ammonificated organic matter (OM) to ammonium, fixed N<sub>2</sub> to ammonium, and nitrified aerobically heterotrophically produced ammonium to nitrate and nitrite. In type 2, sponges (<em>Halichondria</em> sp., Sceptrulophora, <em>Suberites</em>, <em>Tedania</em>) respired OM aerobically and ammonificated it to ammonium. They also reduced nitrate anaerobically to ammonium via dissimilatory nitrate reduction to amm
{"title":"Nutrient fluxes, oxygen consumption and fatty acid composition from deep-water demo- and hexactinellid sponges from New Zealand","authors":"Tanja Stratmann , Kathrin Busch , Anna de Kluijver , Michelle Kelly , Sadie Mills , Sven Rossel , Peter J. Schupp","doi":"10.1016/j.dsr.2024.104416","DOIUrl":"10.1016/j.dsr.2024.104416","url":null,"abstract":"<div><div>Sponges are an important component of deep-water ecosystems enhancing eukaryotic biodiversity by hosting diverse endo- and epibiota and providing three dimensional habitats for benthic invertebrates and fishes. As holobionts they are important hosts of microorganisms which are involved in carbon and nitrogen cycling. While increasing exploration of deep-water habitats results in new sponge species being discovered, little is known about their physiology and role in nutrient fluxes. Around New Zealand (Southwest Pacific), the sponge biodiversity is particularly high, and we selected six deep-sea sponge genera (<em>Saccocalyx</em>, <em>Suberites</em>, <em>Tedania</em>, <em>Halichondria</em>/<em>Dendoricella</em>, <em>Lissodendoryx</em>) and a member of the Sceptrulophora order for <em>in-situ</em> and <em>ex-situ</em> experiments.</div><div>We investigated the biochemical composition of the sponges, measured oxygen consumption and inorganic nutrient fluxes, as well as bacterial and phospholipid-derived fatty acid (PLFA) compositions. Our aim was to assess differences in fluxes and fatty acid composition among sponges and linking their bacterial communities to nitrogen cycling processes.</div><div>All sponges excreted nitrite and ammonia. Nitrate and phosphate excretion were independent of phylum affiliation (Demospongiae, Hexactinellida). Nitrate was excreted by <em>Halichondria</em>/<em>Dendoricella</em> and <em>Lissodendoryx</em>, whereas <em>Suberites</em>, <em>Tedania</em>, and Sceptrulophora consumed it. Phosphate was excreted by Sceptrulophora and <em>Halichondria</em>/<em>Dendoricella</em> and consumed by all other sponges. Oxygen consumption rates ranged from 0.17 to 3.56 ± 0.60 mmol O<sub>2</sub> g C<sup>-1</sup> d<sup>−1</sup>.</div><div>The PLFA composition was very sponge-genera dependent and consisted mostly of long-chain fatty acids. Most PLFAs were sponge-specific, followed by bacteria-specific PLFAs, and others.</div><div>All sponges, except for <em>Suberites</em>, were low-microbial abundance (LMA) sponges whose bacterial community composition was dominated by Proteobacteria, Bacteroidota, Planctomycetota, and Nitrospinota. <em>Suberites</em> consisted of high-microbial abundance (HMA) sponges with Proteobacteria, Chloroflexota, Acidobacteriota, and Actinobacteriota as dominant bacteria.</div><div>Based on the inorganic nitrogen flux measurements, we identified three types of nitrogen cycling in the sponges: In type 1, sponges (<em>Dendoricella</em> spp. indet., <em>Lissodendoryx</em>) respired aerobically and ammonificated organic matter (OM) to ammonium, fixed N<sub>2</sub> to ammonium, and nitrified aerobically heterotrophically produced ammonium to nitrate and nitrite. In type 2, sponges (<em>Halichondria</em> sp., Sceptrulophora, <em>Suberites</em>, <em>Tedania</em>) respired OM aerobically and ammonificated it to ammonium. They also reduced nitrate anaerobically to ammonium via dissimilatory nitrate reduction to amm","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"214 ","pages":"Article 104416"},"PeriodicalIF":2.3,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deep waters (>150 m) shelter half of the extant diversity of scleractinian corals, including framework reef-forming species. However, to date, the relationship between microorganisms and corals has focused mainly on their zooxanthellate shallow-water counterparts. Here, using 16S rRNA gene amplicon sequencing, we explore the microbiome of all major Atlantic deep-water scleractinian reef framework engineers (Desmophyllum pertusum, Solenosmilia variabilis, Madrepora oculata, and Enallopsammia rostrata), and correlated them with environmental characteristics. Colony fragments of each coral species used in the present study were sampled from three sedimentary basins off the Southeastern coast of Brazil, including two water masses (Antarctic Intermediate Water and South Atlantic Coastal Water). Although representing distant scleractinian evolutionarily lineages, some evolving apart for more than 300Ma, our results suggest a taxonomic homogeneity in their microbial profile. The species-specific microbial core, as well as the core common to all examined species, were identified. Such cores are composed of bacterial genera that have already been observed in other coral species, including those from zooxanthellate species. Such a pattern suggests an active selection of the microbial community by their hosts, a phenomenon that seems to be fundamental for holobiont fitness, especially in long-lived species, such as corals. Besides the microbial core, for all examined species, part of the determined microbiome was flexible and responded to environmental drivers. This flexibility is most probably related to the host's ability to adapt in ecological time scales. Taken together, these holobiont abilities may be crucial to its success in both ecological and geological timescales.
{"title":"The microbiome of the main deep-water scleractinian reef-framework engineers from the Southwestern Atlantic","authors":"Aline Aparecida Zanotti , Kátia Cristina Cruz Capel , Carla Zilberberg , Marcelo Visentini Kitahara","doi":"10.1016/j.dsr.2024.104417","DOIUrl":"10.1016/j.dsr.2024.104417","url":null,"abstract":"<div><div>Deep waters (>150 m) shelter half of the extant diversity of scleractinian corals, including framework reef-forming species. However, to date, the relationship between microorganisms and corals has focused mainly on their zooxanthellate shallow-water counterparts. Here, using 16S rRNA gene amplicon sequencing, we explore the microbiome of all major Atlantic deep-water scleractinian reef framework engineers (<em>Desmophyllum pertusum</em>, <em>Solenosmilia variabilis</em>, <em>Madrepora oculata</em>, and <em>Enallopsammia rostrata</em>), and correlated them with environmental characteristics. Colony fragments of each coral species used in the present study were sampled from three sedimentary basins off the Southeastern coast of Brazil, including two water masses (Antarctic Intermediate Water and South Atlantic Coastal Water). Although representing distant scleractinian evolutionarily lineages, some evolving apart for more than 300Ma, our results suggest a taxonomic homogeneity in their microbial profile. The species-specific microbial core, as well as the core common to all examined species, were identified. Such cores are composed of bacterial genera that have already been observed in other coral species, including those from zooxanthellate species. Such a pattern suggests an active selection of the microbial community by their hosts, a phenomenon that seems to be fundamental for holobiont fitness, especially in long-lived species, such as corals. Besides the microbial core, for all examined species, part of the determined microbiome was flexible and responded to environmental drivers. This flexibility is most probably related to the host's ability to adapt in ecological time scales. Taken together, these holobiont abilities may be crucial to its success in both ecological and geological timescales.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"214 ","pages":"Article 104417"},"PeriodicalIF":2.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/j.dsr.2024.104413
Fernanda S. Orrego , Hugo A. Benítez , Manuel I. Castillo , Nicolás Cumplido , Alejandra Fabres , Yanara Figueroa-González , Claudia Morales , Francisca Zavala-Muñoz , Mauricio F. Landaeta
Lanternfish larval morphology is highly variable probably due to their adaptations to highly variable environmental conditions throughout ontogeny. To study the morphological variability of the larval stage of lanternfishes, samples were collected from the southeast Pacific Ocean between 2014 and 2022. Of the 24 species, nine belonged to the subfamily Lampanyctinae, two to the subfamily Diaphinae, one to the subfamily Notolychinae, one to the subfamily Gymnoscopelinae and 11 to the subfamily Myctophinae. A principal component analysis indicated the presence of body shapes varying from a slender and curved body, and upper jaw oriented downwards, with relatively rounded eyes, to taxa with robust bodies, particularly both the head and trunk, and elongated eyes in a dorsal-ventral plane (PC1 33%). Also, specimens varied from having short jaw, short snout, and slender body, to specimens with larger jaw (reaching behind the eye) and taller snout and trunk (PC2, 23%). Allometric effects were related to variations in body curvature and thickness (Diaphus theta, 12.9%), the curvature of the body and position of the eyes (Lampanyctodes hectoris, 25.1%), lengthening of the jaw and increase in eye size (Diogenichthys atlanticus, 24.6%), and a narrower body and smaller eyes (Hygophum bruuni, 20.5%). Four of the five subfamilies showed covariation between morphometrics and environmental conditions. Diaphinae, Gymnoscopelinae and Lampanyctinae body shape covaried with mean sea temperature of the water column, while Myctophinae larval shape covaried with mean salinity. In conclusion, this study quantifies shape variations during early lanternfish ontogeny from the southeastern Pacific Ocean, identifying main differences and allometric changes between the subfamilies belonging to Myctophidae, with a covariation between the shape of most lanternfish larvae and the environmental conditions experienced by myctophid early stages.
{"title":"Morphospace of lanternfish larvae and their interplay with oceanographic conditions from the southeastern Pacific Ocean","authors":"Fernanda S. Orrego , Hugo A. Benítez , Manuel I. Castillo , Nicolás Cumplido , Alejandra Fabres , Yanara Figueroa-González , Claudia Morales , Francisca Zavala-Muñoz , Mauricio F. Landaeta","doi":"10.1016/j.dsr.2024.104413","DOIUrl":"10.1016/j.dsr.2024.104413","url":null,"abstract":"<div><div>Lanternfish larval morphology is highly variable probably due to their adaptations to highly variable environmental conditions throughout ontogeny. To study the morphological variability of the larval stage of lanternfishes, samples were collected from the southeast Pacific Ocean between 2014 and 2022. Of the 24 species, nine belonged to the subfamily Lampanyctinae, two to the subfamily Diaphinae, one to the subfamily Notolychinae, one to the subfamily Gymnoscopelinae and 11 to the subfamily Myctophinae. A principal component analysis indicated the presence of body shapes varying from a slender and curved body, and upper jaw oriented downwards, with relatively rounded eyes, to taxa with robust bodies, particularly both the head and trunk, and elongated eyes in a dorsal-ventral plane (PC1 33%). Also, specimens varied from having short jaw, short snout, and slender body, to specimens with larger jaw (reaching behind the eye) and taller snout and trunk (PC2, 23%). Allometric effects were related to variations in body curvature and thickness (<em>Diaphus theta</em>, 12.9%), the curvature of the body and position of the eyes (<em>Lampanyctodes hectoris</em>, 25.1%), lengthening of the jaw and increase in eye size (<em>Diogenichthys atlanticus</em>, 24.6%), and a narrower body and smaller eyes (<em>Hygophum bruuni</em>, 20.5%). Four of the five subfamilies showed covariation between morphometrics and environmental conditions. Diaphinae, Gymnoscopelinae and Lampanyctinae body shape covaried with mean sea temperature of the water column, while Myctophinae larval shape covaried with mean salinity. In conclusion, this study quantifies shape variations during early lanternfish ontogeny from the southeastern Pacific Ocean, identifying main differences and allometric changes between the subfamilies belonging to Myctophidae, with a covariation between the shape of most lanternfish larvae and the environmental conditions experienced by myctophid early stages.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"214 ","pages":"Article 104413"},"PeriodicalIF":2.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.dsr.2024.104406
Nicholas Bock , Joaquim Goes , Hervé Claustre , Vincent Taillandier , Helga do Rosario Gomes
The Arabian Sea is a highly productive tropical ecosystem of the Indian Ocean that supports high fluxes of particulate organic carbon to the mesopelagic zone from two distinct periods of elevated biological productivity associated with the semiannual reversals of the monsoonal wind system. There are now strong indications that the Arabian Sea's monsoonal wind patterns and hydrographic conditions are being impacted by long-term temperature increases, but the consequences of these changes on primary production and carbon export to the mesopelagic zone are unknown. This is especially true for the summer monsoon period when cloud cover obscures much of the Arabian Sea basin and therefore precludes remotely sensed ocean color measurements for estimating phytoplankton biomass and productivity. Here we overcome this limitation by using a database of bio-optical profiles from Biogeochemical Argo floats collected over the last decade to evaluate the impact of interannual temperature increases on Arabian Sea primary production and carbon export. We classify individual years of float observations based on the spatial extent of the Arabian Sea Mini Warm Pool that appears in the southeast Arabian Sea before the onset of the summer monsoon. This Mini Warm Pool, which begins to build in winter and collapses with the onset of the summer monsoon in late spring, has gained considerable interest on account of its influence on the timing of the onset of the summer monsoon. We observed a 35 percent decrease in primary production during the summer monsoon phytoplankton bloom in strong warm pool years, and a 13 percent decrease in particle stocks in the upper mesopelagic zone following the peak of the bloom. Decreases in production and export were additionally accompanied by a decrease in average particle size, indicating a shift from larger cells like diatoms that appear from fertilization of the oligotrophic waters to smaller phytoplankton size classes in response to a deepening of the thermocline and increased stratification of the water column. These results suggest changes in phytoplankton community structure and further decreases in primary production and carbon export in the Arabian Sea in response to future warming.
{"title":"Influence of mini warm pool extent on phytoplankton productivity and export in the Arabian sea","authors":"Nicholas Bock , Joaquim Goes , Hervé Claustre , Vincent Taillandier , Helga do Rosario Gomes","doi":"10.1016/j.dsr.2024.104406","DOIUrl":"10.1016/j.dsr.2024.104406","url":null,"abstract":"<div><div>The Arabian Sea is a highly productive tropical ecosystem of the Indian Ocean that supports high fluxes of particulate organic carbon to the mesopelagic zone from two distinct periods of elevated biological productivity associated with the semiannual reversals of the monsoonal wind system. There are now strong indications that the Arabian Sea's monsoonal wind patterns and hydrographic conditions are being impacted by long-term temperature increases, but the consequences of these changes on primary production and carbon export to the mesopelagic zone are unknown. This is especially true for the summer monsoon period when cloud cover obscures much of the Arabian Sea basin and therefore precludes remotely sensed ocean color measurements for estimating phytoplankton biomass and productivity. Here we overcome this limitation by using a database of bio-optical profiles from Biogeochemical Argo floats collected over the last decade to evaluate the impact of interannual temperature increases on Arabian Sea primary production and carbon export. We classify individual years of float observations based on the spatial extent of the Arabian Sea Mini Warm Pool that appears in the southeast Arabian Sea before the onset of the summer monsoon. This Mini Warm Pool, which begins to build in winter and collapses with the onset of the summer monsoon in late spring, has gained considerable interest on account of its influence on the timing of the onset of the summer monsoon. We observed a 35 percent decrease in primary production during the summer monsoon phytoplankton bloom in strong warm pool years, and a 13 percent decrease in particle stocks in the upper mesopelagic zone following the peak of the bloom. Decreases in production and export were additionally accompanied by a decrease in average particle size, indicating a shift from larger cells like diatoms that appear from fertilization of the oligotrophic waters to smaller phytoplankton size classes in response to a deepening of the thermocline and increased stratification of the water column. These results suggest changes in phytoplankton community structure and further decreases in primary production and carbon export in the Arabian Sea in response to future warming.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"214 ","pages":"Article 104406"},"PeriodicalIF":2.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.dsr.2024.104414
Bruce H. Robison , Steven H.D. Haddock
We describe an exceptional nudibranch, new to science, from bathypelagic depths in the eastern North Pacific Ocean. More than 100 individuals of Bathydevius caudactylus gen. et. sp. nov. have been observed in the water column at depths between 1013 and 3272 m. Twenty spawning individuals were observed on the seafloor at depths between 2269 and 4009 m. Anatomy, diet, behavior, bioluminescence, and habitat distinguish this surprising nudibranch from all previously described species, and genetic evidence supports its placement in a new family.
我们描述了一种来自北太平洋东部深海水层的特殊裸鳃动物，它是科学界的新发现。我们在水深 1013 米至 3272 米的水体中观察到了 100 多条 Bathydevius caudactylus gen.
{"title":"Discovery and description of a remarkable bathypelagic nudibranch, Bathydevius caudactylus, gen. et. sp. nov.","authors":"Bruce H. Robison , Steven H.D. Haddock","doi":"10.1016/j.dsr.2024.104414","DOIUrl":"10.1016/j.dsr.2024.104414","url":null,"abstract":"<div><div>We describe an exceptional nudibranch, new to science, from bathypelagic depths in the eastern North Pacific Ocean. More than 100 individuals of <em>Bathydevius caudactylus</em> gen. et. sp. nov. have been observed in the water column at depths between 1013 and 3272 m. Twenty spawning individuals were observed on the seafloor at depths between 2269 and 4009 m. Anatomy, diet, behavior, bioluminescence, and habitat distinguish this surprising nudibranch from all previously described species, and genetic evidence supports its placement in a new family.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"214 ","pages":"Article 104414"},"PeriodicalIF":2.3,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-13DOI: 10.1016/j.dsr.2024.104405
Kolisa Yola Sinyanya , Tanya A. Marshall , Raquel F. Flynn , Eesaa Harris , Mhlangabezi Mdutyana , Raymond Roman , David R. Walker , Sina Wallschuss , Sarah E. Fawcett
The Agulhas Current plays a major role in heat and salt exchange between the Indian and Atlantic Oceans, yet little is known of its influence on ocean fertility. To investigate carbon production and export potential in the Agulhas Current system, we measured net primary production (NPP), nitrate and ammonium uptake, N2 fixation, and nitrification along a transect of the current and adjacent subtropical subgyre (33.4°S–35.7°S) in winter when nutrient supply, and thus productivity, should be highest. Phytoplankton biomass was lowest in the current core, increasing into the subgyre as surface nitrate declined, and was dominated by nanoplankton (2.7–10 μm; 62 ± 5.1% of total biomass). NPP and nitrate uptake were generally high across the transect and increased from the current core into the subgyre; the rates were dominated by picoplankton (<2.7 μm; 53–93%) in the current core and nanoplankton elsewhere (63–69%). On average, euphotic zone nitrification supplied 7.6 ± 6.4% of the nitrate consumed by phytoplankton and N2 fixation was also low (2.1 ± 1.3% of new production); we thus consider nitrate uptake a reasonable proxy for new production, at least in winter. Nitrate uptake was highest at the southern edge of the current core, consistent with current-associated (sub)mesoscale mixing enhancing the upward nutrient supply. The fraction of NPP available for export (i.e., the f-ratio) was high across the transect, ranging from 0.44 to 0.69. Our data thus indicate that both total and new production are elevated across the Agulhas Current system in winter and suggest that the (sub)mesoscale dynamics associated with the current system may enhance carbon production and export in the otherwise oligotrophic southwest Indian Ocean.
{"title":"Wintertime productivity and carbon export potential across the Agulhas Current system","authors":"Kolisa Yola Sinyanya , Tanya A. Marshall , Raquel F. Flynn , Eesaa Harris , Mhlangabezi Mdutyana , Raymond Roman , David R. Walker , Sina Wallschuss , Sarah E. Fawcett","doi":"10.1016/j.dsr.2024.104405","DOIUrl":"10.1016/j.dsr.2024.104405","url":null,"abstract":"<div><div>The Agulhas Current plays a major role in heat and salt exchange between the Indian and Atlantic Oceans, yet little is known of its influence on ocean fertility. To investigate carbon production and export potential in the Agulhas Current system, we measured net primary production (NPP), nitrate and ammonium uptake, N<sub>2</sub> fixation, and nitrification along a transect of the current and adjacent subtropical subgyre (33.4°S–35.7°S) in winter when nutrient supply, and thus productivity, should be highest. Phytoplankton biomass was lowest in the current core, increasing into the subgyre as surface nitrate declined, and was dominated by nanoplankton (2.7–10 μm; 62 ± 5.1% of total biomass). NPP and nitrate uptake were generally high across the transect and increased from the current core into the subgyre; the rates were dominated by picoplankton (<2.7 μm; 53–93%) in the current core and nanoplankton elsewhere (63–69%). On average, euphotic zone nitrification supplied 7.6 ± 6.4% of the nitrate consumed by phytoplankton and N<sub>2</sub> fixation was also low (2.1 ± 1.3% of new production); we thus consider nitrate uptake a reasonable proxy for new production, at least in winter. Nitrate uptake was highest at the southern edge of the current core, consistent with current-associated (sub)mesoscale mixing enhancing the upward nutrient supply. The fraction of NPP available for export (i.e., the <em>f</em>-ratio) was high across the transect, ranging from 0.44 to 0.69. Our data thus indicate that both total and new production are elevated across the Agulhas Current system in winter and suggest that the (sub)mesoscale dynamics associated with the current system may enhance carbon production and export in the otherwise oligotrophic southwest Indian Ocean.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"213 ","pages":"Article 104405"},"PeriodicalIF":2.3,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.dsr.2024.104403
Tal Ben Ezra , Alon Blachinsky , Shiran Gozali , Anat Tsemel , Yotam Fadida , Dan Tchernov , Yoav Lehahn , Tatiana Margo Tsagaraki , Ilana Berman-Frank , Michael Krom
Global climate change is predicted to reduce nutrient fluxes into the photic zone, particularly in tropical and subtropical ocean gyres, while the occasional major storms will result in increased nutrient pulses. In this study the nutrient and phytoplankton dynamics have been determined at a new time-series station in the southeastern Levantine basin of the Eastern Mediterranean Sea (EMS) over 4.5 years (2017–2022). In 2018 and 2019, there was a moderate concentration of residual nitrate and nitrite (N + N) in the photic zone (280–410 nM) in winter, resulting in phytoplankton dynamics dominated by cyanobacteria with relatively few picoeukaryotes (280 ± 90 μgC m−2). Winter storm driven mixing was much reduced in 2020 and particularly in 2021, resulting in a lower concentration of N + N in the photic zone, which decreased during summer stratification, such that by August 2021, the N + N was highly depleted (<60 nM) resulting in an integrated phytoplankton biomass of 23 μgC m−2. A major storm in December 2021 (Storm Carmel) injected high N + N (750 nM; max = 1090 nM) in the upper 100 m, which stimulated pico and nanophytoplankton biomass (∼2400 μgC m−2) and according to our inference increased eukaryotes (diatoms). The pattern of measured silica reinforced our conclusion that we sampled 3 different nutrient and ecosystem states. Phosphate was always at or close to limit of detection (LoD) because of rapid uptake by cyanobacteria into their periplasm. These results predict that climate change in the EMS will result in periods of nutrient and phytoplankton depletion (Famine) interrupted by short periods of Mesotrophy (Feast) caused by major storms.
{"title":"Interannual changes in nutrient and phytoplankton dynamics in the Eastern Mediterranean Sea (EMS) predict the consequences of climate change; results from the Sdot-Yam Time-series station 2018–2022","authors":"Tal Ben Ezra , Alon Blachinsky , Shiran Gozali , Anat Tsemel , Yotam Fadida , Dan Tchernov , Yoav Lehahn , Tatiana Margo Tsagaraki , Ilana Berman-Frank , Michael Krom","doi":"10.1016/j.dsr.2024.104403","DOIUrl":"10.1016/j.dsr.2024.104403","url":null,"abstract":"<div><div>Global climate change is predicted to reduce nutrient fluxes into the photic zone, particularly in tropical and subtropical ocean gyres, while the occasional major storms will result in increased nutrient pulses. In this study the nutrient and phytoplankton dynamics have been determined at a new time-series station in the southeastern Levantine basin of the Eastern Mediterranean Sea (EMS) over 4.5 years (2017–2022). In 2018 and 2019, there was a moderate concentration of residual nitrate and nitrite (N + N) in the photic zone (280–410 nM) in winter, resulting in phytoplankton dynamics dominated by cyanobacteria with relatively few picoeukaryotes (280 ± 90 μgC m<sup>−2</sup>). Winter storm driven mixing was much reduced in 2020 and particularly in 2021, resulting in a lower concentration of N + N in the photic zone, which decreased during summer stratification, such that by August 2021, the N + N was highly depleted (<60 nM) resulting in an integrated phytoplankton biomass of 23 μgC m<sup>−2</sup>. A major storm in December 2021 (Storm Carmel) injected high N + N (750 nM; max = 1090 nM) in the upper 100 m, which stimulated pico and nanophytoplankton biomass (∼2400 μgC m<sup>−2</sup>) and according to our inference increased eukaryotes (diatoms). The pattern of measured silica reinforced our conclusion that we sampled 3 different nutrient and ecosystem states. Phosphate was always at or close to limit of detection (LoD) because of rapid uptake by cyanobacteria into their periplasm. These results predict that climate change in the EMS will result in periods of nutrient and phytoplankton depletion (Famine) interrupted by short periods of Mesotrophy (Feast) caused by major storms.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"213 ","pages":"Article 104403"},"PeriodicalIF":2.3,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-03DOI: 10.1016/j.dsr.2024.104404
Tobias Schulzki , Lea-Anne Henry , J. Murray Roberts , Maria Rakka , Steve W. Ross , Arne Biastoch
The sinking of the RMS Titanic on 15 April 1912 remains one of most iconic maritime disasters in history. Today, the wreck site lies in waters 3800 m deep approximately 690 km south southeast of Newfoundland, Atlantic Canada. The wreck and debris field have been colonized by many marine organisms including the octocoral Chrysogorgia agassizii. Because of the rapid deterioration of the Titanic and the vulnerability of natural deep-sea coral populations to environmental changes, it is vital to understand the role the Titanic as well as other such structures could play in connecting ecosystems along the North American slope. Based on Lagrangian experiments with more than one million virtual particles and different scenarios for larval behavior, given the uncertainties around the biology of chrysogorgiids, the dispersal of larvae spawned at the Titanic wreck is studied in a high-resolution numerical ocean model. While the large-scale bathymetry shields the Titanic from a strong mean flow, mesoscale ocean eddies can considerably affect the deep circulation and cause a significant speed up, or also a reversal, of the circulation. As a consequence, the position of upper and mid-ocean eddies in the model largely controls the direction and distance of larval dispersal, with the impact of eddies outweighing the importance of active larval swimming in our experiments. Although dependent on larval buoyancy and longevity, we find that the Titanic could be reached by larvae spawned on the upper slope east of the Grand Banks. Therefore, the Titanic could act as a stepping stone connecting the upper to the deep continental slope off Newfoundland. From the Titanic, larvae then spread into deep Canadian waters and areas beyond national jurisdiction.
{"title":"Mesoscale ocean eddies determine dispersal and connectivity of corals at the RMS Titanic wreck site","authors":"Tobias Schulzki , Lea-Anne Henry , J. Murray Roberts , Maria Rakka , Steve W. Ross , Arne Biastoch","doi":"10.1016/j.dsr.2024.104404","DOIUrl":"10.1016/j.dsr.2024.104404","url":null,"abstract":"<div><div>The sinking of the RMS <em>Titanic</em> on 15 April 1912 remains one of most iconic maritime disasters in history. Today, the wreck site lies in waters 3800 m deep approximately 690 km south southeast of Newfoundland, Atlantic Canada. The wreck and debris field have been colonized by many marine organisms including the octocoral <em>Chrysogorgia agassizii</em>. Because of the rapid deterioration of the <em>Titanic</em> and the vulnerability of natural deep-sea coral populations to environmental changes, it is vital to understand the role the <em>Titanic</em> as well as other such structures could play in connecting ecosystems along the North American slope. Based on Lagrangian experiments with more than one million virtual particles and different scenarios for larval behavior, given the uncertainties around the biology of <em>chrysogorgiids</em>, the dispersal of larvae spawned at the <em>Titanic</em> wreck is studied in a high-resolution numerical ocean model. While the large-scale bathymetry shields the <em>Titanic</em> from a strong mean flow, mesoscale ocean eddies can considerably affect the deep circulation and cause a significant speed up, or also a reversal, of the circulation. As a consequence, the position of upper and mid-ocean eddies in the model largely controls the direction and distance of larval dispersal, with the impact of eddies outweighing the importance of active larval swimming in our experiments. Although dependent on larval buoyancy and longevity, we find that the <em>Titanic</em> could be reached by larvae spawned on the upper slope east of the Grand Banks. Therefore, the <em>Titanic</em> could act as a stepping stone connecting the upper to the deep continental slope off Newfoundland. From the <em>Titanic</em>, larvae then spread into deep Canadian waters and areas beyond national jurisdiction.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"213 ","pages":"Article 104404"},"PeriodicalIF":2.3,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.dsr.2024.104402
Jiang Gui , Yingjie Mao , Jun Sun , Mao Lin
The Western Pacific Ocean (WPO) is one of the most active eddy regions in the world, where a variety of ocean processes are frequently observed, but little research has been conducted on the phytoplankton communities and their photosynthetic physiological status within the eddies in this region. The bio-optical parameters of phytoplankton communities and their physiological status within the warm core and cold core eddies of the WPO during the winter of 2021 were investigated based on fast repetition rate fluorometry (FRRF). In this paper, environmental factors, phytoplankton community parameters, chlorophyll a (Chl a), and various bio-optical parameters were investigated for two opposite types of eddies at the WPO. The results show the maximum [Fv/Fm, 0.18 to 0.26 (warm eddy), 0.14 to 0.28 (cold eddy)] and effective photosynthetic efficiency [Fq'/Fm', 0.11 to 0.23 (warm eddy), 0.10 to 0.27 (cold eddy)] of the DCM for both warm and cold eddies, the electron transport rates ETRRCII [0.002–6.18 mol e− mol RCII−1 s−1 (warm eddy), 0.002–4.94 mol e− mol RCII−1 s−1 (cold eddy)] and the primary production potential PPmax [0.68–118.19 mg C (mg Chl a)−1 day−1 (warm eddy), 2.47–243.49 mg C (mg Chl a)−1 day−1 (cold eddy)] for different types eddies. In warm eddy, temperature and Chl a concentrations had significant effects on Fv/Fm and Fq'/Fm', while in cold eddy the correlation of Fv/Fm and Fq'/Fm' with temperature was not significant, and Fv/Fm was significantly negatively correlated with DIP only. Light was the main variable affecting the electron transport capacity and primary production potential of the phytoplankton community in the eddies, while larger cyanobacteria and dinoflagellates contributed significantly to the primary production potential of the cold eddy. In addition, both eddies centers had higher primary production potentials, with the cold eddy had a higher primary production potential than the warm eddy, based on microscopic analysis this phenomenon may be due to differences in electron transfer rates between phytoplankton communities.
{"title":"Photophysiological status of phytoplankton communities in different types of eddies during winter in the western Pacific Ocean","authors":"Jiang Gui , Yingjie Mao , Jun Sun , Mao Lin","doi":"10.1016/j.dsr.2024.104402","DOIUrl":"10.1016/j.dsr.2024.104402","url":null,"abstract":"<div><div>The Western Pacific Ocean (WPO) is one of the most active eddy regions in the world, where a variety of ocean processes are frequently observed, but little research has been conducted on the phytoplankton communities and their photosynthetic physiological status within the eddies in this region. The bio-optical parameters of phytoplankton communities and their physiological status within the warm core and cold core eddies of the WPO during the winter of 2021 were investigated based on fast repetition rate fluorometry (FRRF). In this paper, environmental factors, phytoplankton community parameters, chlorophyll <em>a</em> (Chl <em>a</em>), and various bio-optical parameters were investigated for two opposite types of eddies at the WPO. The results show the maximum [Fv/Fm, 0.18 to 0.26 (warm eddy), 0.14 to 0.28 (cold eddy)] and effective photosynthetic efficiency [Fq'/Fm', 0.11 to 0.23 (warm eddy), 0.10 to 0.27 (cold eddy)] of the DCM for both warm and cold eddies, the electron transport rates ETR<sub>RCII</sub> [0.002–6.18 mol e<sup>−</sup> mol RCII<sup>−1</sup> s<sup>−1</sup> (warm eddy), 0.002–4.94 mol e<sup>−</sup> mol RCII<sup>−1</sup> s<sup>−1</sup> (cold eddy)] and the primary production potential <em>PP</em><sub>max</sub> [0.68–118.19 mg C (mg Chl <em>a</em>)<sup>−1</sup> day<sup>−1</sup> (warm eddy), 2.47–243.49 mg C (mg Chl <em>a</em>)<sup>−1</sup> day<sup>−1</sup> (cold eddy)] for different types eddies. In warm eddy, temperature and Chl <em>a</em> concentrations had significant effects on Fv/Fm and Fq'/Fm', while in cold eddy the correlation of Fv/Fm and Fq'/Fm' with temperature was not significant, and Fv/Fm was significantly negatively correlated with DIP only. Light was the main variable affecting the electron transport capacity and primary production potential of the phytoplankton community in the eddies, while larger cyanobacteria and dinoflagellates contributed significantly to the primary production potential of the cold eddy. In addition, both eddies centers had higher primary production potentials, with the cold eddy had a higher primary production potential than the warm eddy, based on microscopic analysis this phenomenon may be due to differences in electron transfer rates between phytoplankton communities.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"213 ","pages":"Article 104402"},"PeriodicalIF":2.3,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1016/j.dsr.2024.104401
Shijun Wu , Zhiheng Chen , Shuo Wang , Jian Zhang , Canjun Yang
Research on deep seawater is of great importance to marine chemistry, biology, and climate science studies. Sample analysis is the fundamental and most effective method for deep-seawater research, and it is essential to collect high-quality water samples for the scientific community. Over nearly a century, various deep-seawater samplers have been developed to meet different research needs. This study provides a comprehensive review of deep-seawater sampling technology and instruments to highlight the associated research background and importance, summarize sampling principles, and categorize typical samplers. This review focuses on the key technologies that deep-seawater samplers perform, including sealing, pressure maintenance, and temperature maintenance. Finally, prospects are presented in terms of three aspects: high fidelity, long-term series sampling, and precise sampling using autonomous underwater vehicles. This review can serve as a reference to achieve the precise sampling of deep seawater with high fidelity and spatiotemporal resolution in the future.
{"title":"A review of deep-seawater samplers: Principles, applications, performance, and trends","authors":"Shijun Wu , Zhiheng Chen , Shuo Wang , Jian Zhang , Canjun Yang","doi":"10.1016/j.dsr.2024.104401","DOIUrl":"10.1016/j.dsr.2024.104401","url":null,"abstract":"<div><p>Research on deep seawater is of great importance to marine chemistry, biology, and climate science studies. Sample analysis is the fundamental and most effective method for deep-seawater research, and it is essential to collect high-quality water samples for the scientific community. Over nearly a century, various deep-seawater samplers have been developed to meet different research needs. This study provides a comprehensive review of deep-seawater sampling technology and instruments to highlight the associated research background and importance, summarize sampling principles, and categorize typical samplers. This review focuses on the key technologies that deep-seawater samplers perform, including sealing, pressure maintenance, and temperature maintenance. Finally, prospects are presented in terms of three aspects: high fidelity, long-term series sampling, and precise sampling using autonomous underwater vehicles. This review can serve as a reference to achieve the precise sampling of deep seawater with high fidelity and spatiotemporal resolution in the future.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"213 ","pages":"Article 104401"},"PeriodicalIF":2.3,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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