Pub Date : 2025-08-20DOI: 10.1016/j.dsr2.2025.105532
Mehrshad Taheri , Mohammad Ali Hamzeh , Abolfazl Saleh , Maryam Yazdani Foshtomi , Ahmad Radmanesh
Understanding the drivers of nematode community structure in subtidal ecosystems is critical for assessing marine biodiversity and ecosystem health. As sensitive bioindicators of environmental change, marine nematodes provide crucial insights into ecosystem dynamics; however, their spatial distribution patterns in the Persian Gulf's subtidal zones remain poorly understood. This study investigates the spatial variability of free–living nematode communities across five distinct transects in this understudied region. A total of 2189 specimens, representing 60 different genera, were identified. Nematode density showed significant variation, ranging from 16.7 to 92.6 individuals in 10 cm2, with the highest densities typically found at the shallowest stations. The average number of genera per sample ranged from 1 to 18.67. The Shannon diversity indices varied significantly, with a maximum of 2.58 and a minimum of 0, while evenness scores ranged from 0.76 to 1. Notable differences in nematode community structure were observed across the various transects and stations. The overall nematode community was dominated by genera such as Actinonema, Axonolaimus, Dorylaimopsis, Gnomoxyala, Halalaimus, Hopperia, Marylynnia, Pierrickia, Sabatieria, Subsphaerolaimus, and Terschellingia across different transects. According to DistLM analysis, depth, salinity, mean grain size, pH, and temperature together explained 22.9 % of the total variance in the nematode community, with depth accounting for 9.3 % and the other significant variables contributing an additional 13.6 %. Further research is essential to clarify the relationship between nematode communities and environmental conditions in underexplored ecosystems like this region.
{"title":"Distribution of free–Living marine nematodes along environmental gradients in the strait of hormuz","authors":"Mehrshad Taheri , Mohammad Ali Hamzeh , Abolfazl Saleh , Maryam Yazdani Foshtomi , Ahmad Radmanesh","doi":"10.1016/j.dsr2.2025.105532","DOIUrl":"10.1016/j.dsr2.2025.105532","url":null,"abstract":"<div><div>Understanding the drivers of nematode community structure in subtidal ecosystems is critical for assessing marine biodiversity and ecosystem health. As sensitive bioindicators of environmental change, marine nematodes provide crucial insights into ecosystem dynamics; however, their spatial distribution patterns in the Persian Gulf's subtidal zones remain poorly understood. This study investigates the spatial variability of free–living nematode communities across five distinct transects in this understudied region. A total of 2189 specimens, representing 60 different genera, were identified. Nematode density showed significant variation, ranging from 16.7 to 92.6 individuals in 10 cm<sup>2</sup>, with the highest densities typically found at the shallowest stations. The average number of genera per sample ranged from 1 to 18.67. The Shannon diversity indices varied significantly, with a maximum of 2.58 and a minimum of 0, while evenness scores ranged from 0.76 to 1. Notable differences in nematode community structure were observed across the various transects and stations. The overall nematode community was dominated by genera such as <em>Actinonema</em>, <em>Axonolaimus</em>, <em>Dorylaimopsis</em>, <em>Gnomoxyala</em>, <em>Halalaimus</em>, <em>Hopperia</em>, <em>Marylynnia</em>, <em>Pierrickia</em>, <em>Sabatieria</em>, <em>Subsphaerolaimus</em>, and <em>Terschellingia</em> across different transects. According to DistLM analysis, depth, salinity, mean grain size, pH, and temperature together explained 22.9 % of the total variance in the nematode community, with depth accounting for 9.3 % and the other significant variables contributing an additional 13.6 %. Further research is essential to clarify the relationship between nematode communities and environmental conditions in underexplored ecosystems like this region.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105532"},"PeriodicalIF":3.0,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889520","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}
Understanding mesozooplankton (MSP) dynamics in nursery habitats is crucial for assessing ecosystem health and trophic interactions, particularly in anthropogenically stressed yet ecologically significant areas, such as Sulaibikhat Bay – home to Kuwait's first Marine Protected Area (MPA) in the northwestern Arabian/Persian Gulf (NWG). This study examines MSP community dynamics and environmental interactions over 26 months (October 2018–March 2021) across five fixed stations, including sites influenced by desalination and sewage outfalls. Seasonal fluctuations in water temperature, salinity, and nutrients significantly influenced MSP community structure. Copepods dominated, with cyclopoids (Oithona spp.) peaking in summer and fall, while calanoids (Parvocalanus crassirostris, Acartia spp.) were more prevalent in winter and spring. The cyclopoid-to-calanoid ratio, a potential indicator of trophic shifts, varied significantly across seasons, with cyclopoids prevailing in warmer months. Diversity and dispersion patterns, assessed through Venn diagrams and PERMDISP analysis, revealed higher species turnover near polluted sites and greater stability within the MPA. Taxonomic relatedness indices (AvTD, VarTD) indicated reduced diversity in chronically stressed areas. BIOENV and RELATE analyses identified temperature, dissolved oxygen, turbidity, and nanophytoplankton chlorophyll a as key drivers of the MSP community. Significant negative correlations between fish larvae and cyclopoids near the Al-Ghazali sewer outlet suggested potential prey-predator interactions, reinforcing the ecological implications of MSP composition shifts in this nursery habitat. While the MPA supports high MSP diversity, ongoing stressors, such as brine discharge and sewage, continue to shape the MSP community and trophic interactions. This study provides critical insights for ecosystem-based management of marine resources in and around Kuwait's first MPA in the NWG.
{"title":"Mesozooplankton community responses to environmental stressors in Kuwait's first marine protected area","authors":"Rakhesh Madhusoodhanan, Turki Al-Said, Faiza Al-Yamani, Gopikrishna Mantha, Takahiro Yamamoto, Loreta Fernandes, Ayaz Ahmed, Nithyanandan Manickam, Amit Sarkar, Sabeena Habeebullah Koduvayur Habeebullah, Fathima Thuslim, Waleed Al-Zekri, Jessy Sebastian, Maryam Al-Enezi","doi":"10.1016/j.dsr2.2025.105533","DOIUrl":"10.1016/j.dsr2.2025.105533","url":null,"abstract":"<div><div>Understanding mesozooplankton (MSP) dynamics in nursery habitats is crucial for assessing ecosystem health and trophic interactions, particularly in anthropogenically stressed yet ecologically significant areas, such as Sulaibikhat Bay – home to Kuwait's first Marine Protected Area (MPA) in the northwestern Arabian/Persian Gulf (NWG). This study examines MSP community dynamics and environmental interactions over 26 months (October 2018–March 2021) across five fixed stations, including sites influenced by desalination and sewage outfalls. Seasonal fluctuations in water temperature, salinity, and nutrients significantly influenced MSP community structure. Copepods dominated, with cyclopoids (<em>Oithona</em> spp.) peaking in summer and fall, while calanoids (<em>Parvocalanus crassirostris</em>, <em>Acartia</em> spp.) were more prevalent in winter and spring. The cyclopoid-to-calanoid ratio, a potential indicator of trophic shifts, varied significantly across seasons, with cyclopoids prevailing in warmer months. Diversity and dispersion patterns, assessed through Venn diagrams and PERMDISP analysis, revealed higher species turnover near polluted sites and greater stability within the MPA. Taxonomic relatedness indices (AvTD, VarTD) indicated reduced diversity in chronically stressed areas. BIOENV and RELATE analyses identified temperature, dissolved oxygen, turbidity, and nanophytoplankton chlorophyll <em>a</em> as key drivers of the MSP community. Significant negative correlations between fish larvae and cyclopoids near the Al-Ghazali sewer outlet suggested potential prey-predator interactions, reinforcing the ecological implications of MSP composition shifts in this nursery habitat. While the MPA supports high MSP diversity, ongoing stressors, such as brine discharge and sewage, continue to shape the MSP community and trophic interactions. This study provides critical insights for ecosystem-based management of marine resources in and around Kuwait's first MPA in the NWG.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105533"},"PeriodicalIF":3.0,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890809","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 : 2025-08-18DOI: 10.1016/j.dsr2.2025.105534
Emad Koochaknejad, Abolfazl Saleh
Phytoplankton communities play a crucial role in marine ecosystem resilience and biogeochemical cycling, yet their functional responses to environmental fluctuations in extreme environmental conditions like the Persian Gulf remain poorly understood. This study investigates the temporal and spatial structuring of microphytoplankton communities around Khark and Qeshm Islands in the Persian Gulf over an annual cycle (November 2021 to December 2022), integrating taxonomic diversity with a trait-based functional approach to assess adaptive strategies under varying physicochemical conditions. Monthly sampling was conducted at six stations (three per island), and phytoplankton functional diversity was quantified based on nine key traits: photosynthetic pigment composition, growth form, body size, motility, nitrogen-fixing ability, trophic strategy, cell wall composition, long projections, and vertical migration. The results reveal distinct ecological regimes between the two islands. The phytoplankton communities in Qeshm Island are taxonomically diverse but functionally stable, reflecting ecological stability under relatively constant environmental conditions. In contrast, the Khark phytoplankton communities exhibit pronounced seasonal shifts in functional diversity shaped by fluctuations in salinity, carbonate chemistry, and nutrient availability. Clustering analysis identified six functional groups with two dominant assemblages: Group 6 (Trichodesmium erythraeum, a diazotrophic cyanobacterium) and Group 4 (chain-forming diatoms such as Chaetoceros spp.). Carbonate saturation state, nitrate availability, and temperature were identified as key environmental factors shaping both taxonomic and functional community composition (as indicated by Canonical Correspondence Analysis (CCA) and Fourth-Corner Analysis). Furthermore, large-scale Trichodesmium erythraeum blooms in Khark during summer and early autumn significantly altered carbonate system equilibrium, a novel insight into phytoplankton trait-environment relationships in the Persian Gulf, highlighting the capacity of diazotrophic cyanobacteria to drive biogeochemical feedback loops through nitrogen fixation, pH modulation, and shifts in carbonate saturation state, with potential implications for regional carbon cycling.
{"title":"Functional group dynamics and environmental forcing of microphytoplankton in the Persian Gulf: Temporal patterns from Khark and Qeshm Islands","authors":"Emad Koochaknejad, Abolfazl Saleh","doi":"10.1016/j.dsr2.2025.105534","DOIUrl":"10.1016/j.dsr2.2025.105534","url":null,"abstract":"<div><div>Phytoplankton communities play a crucial role in marine ecosystem resilience and biogeochemical cycling, yet their functional responses to environmental fluctuations in extreme environmental conditions like the Persian Gulf remain poorly understood. This study investigates the temporal and spatial structuring of microphytoplankton communities around Khark and Qeshm Islands in the Persian Gulf over an annual cycle (November 2021 to December 2022), integrating taxonomic diversity with a trait-based functional approach to assess adaptive strategies under varying physicochemical conditions. Monthly sampling was conducted at six stations (three per island), and phytoplankton functional diversity was quantified based on nine key traits: photosynthetic pigment composition, growth form, body size, motility, nitrogen-fixing ability, trophic strategy, cell wall composition, long projections, and vertical migration. The results reveal distinct ecological regimes between the two islands. The phytoplankton communities in Qeshm Island are taxonomically diverse but functionally stable, reflecting ecological stability under relatively constant environmental conditions. In contrast, the Khark phytoplankton communities exhibit pronounced seasonal shifts in functional diversity shaped by fluctuations in salinity, carbonate chemistry, and nutrient availability. Clustering analysis identified six functional groups with two dominant assemblages: Group 6 (<em>Trichodesmium erythraeum</em>, a diazotrophic cyanobacterium) and Group 4 (chain-forming diatoms such as <em>Chaetoceros</em> spp.). Carbonate saturation state, nitrate availability, and temperature were identified as key environmental factors shaping both taxonomic and functional community composition (as indicated by Canonical Correspondence Analysis (CCA) and Fourth-Corner Analysis). Furthermore, large-scale <em>Trichodesmium erythraeum</em> blooms in Khark during summer and early autumn significantly altered carbonate system equilibrium, a novel insight into phytoplankton trait-environment relationships in the Persian Gulf, highlighting the capacity of diazotrophic cyanobacteria to drive biogeochemical feedback loops through nitrogen fixation, pH modulation, and shifts in carbonate saturation state, with potential implications for regional carbon cycling.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105534"},"PeriodicalIF":3.0,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890810","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 : 2025-08-15DOI: 10.1016/j.dsr2.2025.105531
Mark J. Hopwood , Martha Gledhill , Eric P. Achterberg , Yuanyuan Gu , Ali A. Al-Hashem , Leila R. Kittu , Stephan Krisch , Insa Rapp
Nickel (Ni) is a bio-essential trace metal used in urease, hydrogenase and superoxide dismutase enzymes. The concentration of dissolved (<0.2 μm) Ni (dNi) in the surface ocean is rarely depleted below ∼2 nM globally. This is in stark contrast to the concentrations of many other bio-essential trace metals such as iron (Fe), cobalt (Co) and manganese (Mn). Both complexation with strong ligands, potentially rendering dNi unavailable to marine organisms, and slow depletion of dNi because of low cellular demand compared to other trace metals have been invoked to explain this peculiar elemental distribution. Here we report new measurements of pelagic dNi concentrations (n = 1094) from four cruises (M135-M138) in the Eastern Tropical South Pacific (ETSP) to evaluate dNi dynamics under variable biogeochemical conditions in a highly productive shelf region. We additionally report total and labile particulate Ni concentrations along two cross-shelf sections at 16° S and 17° S. The ETSP features a productive Eastern Boundary Upwelling System along the Peruvian-Chilean shelf. This coincides with an extensive underlying Oxygen Minimum Zone which leads to persistently high phosphate and intermittently high Fe conditions.
The vast majority of dNi concentrations measured across the Peruvian shelf were within the range 2.2–10.8 nM dNi with highly reproducible depth profiles compared to prior cruises in different seasons, years, and El Niño–Southern Oscillation phases. Evidence of lower dNi concentrations was only found at one inshore location with dNi as low as 1.3 nM. Such low dNi concentrations appear to be rare. Whilst biogenic Ni associated with diatom detritus is buried in Peruvian shelf sediments, biological dNi demand on the Peruvian shelf is <30 % of the annual upwelled dNi flux and burial in shelf sediments accounts for approximately 1–3 % of the upwelled dNi flux. Total particulate Ni concentrations measured on two cross-shelf sections ranged from below detection to 1.2 nM and were consistently low relative to dNi concentrations. On average, total particulate Ni (TpNi) was 2.6 % of dNi + TpNi with labile particulate Ni (LpNi) and TpNi remaining tightly coupled (R2 = 0.99). As is the case elsewhere in the global ocean, dNi remained tightly correlated with phosphate and silicic acid concentrations. Limited biological demand for Ni relative to the upwelled dNi supply explains why dNi profiles in general were quite homogenous across the Peruvian coastal, shelf and offshore regions. Finally, profiles of dNi suggested a slightly lower than average dNi:phosphorous ratio (0.673 mmol (mol P)−1) in the upper water column. Similar distributions of dNi and dNi:phosphorous ratios were found for the Benguela and Mauritania shelves reinforcing the relatively invariable nature of dNi profiles even in extremely productive shelf environments.
{"title":"Invariable nickel dynamics in the Peru, Benguela and Mauritania oxygen minimum zones","authors":"Mark J. Hopwood , Martha Gledhill , Eric P. Achterberg , Yuanyuan Gu , Ali A. Al-Hashem , Leila R. Kittu , Stephan Krisch , Insa Rapp","doi":"10.1016/j.dsr2.2025.105531","DOIUrl":"10.1016/j.dsr2.2025.105531","url":null,"abstract":"<div><div>Nickel (Ni) is a bio-essential trace metal used in urease, hydrogenase and superoxide dismutase enzymes. The concentration of dissolved (<0.2 μm) Ni (dNi) in the surface ocean is rarely depleted below ∼2 nM globally. This is in stark contrast to the concentrations of many other bio-essential trace metals such as iron (Fe), cobalt (Co) and manganese (Mn). Both complexation with strong ligands, potentially rendering dNi unavailable to marine organisms, and slow depletion of dNi because of low cellular demand compared to other trace metals have been invoked to explain this peculiar elemental distribution. Here we report new measurements of pelagic dNi concentrations (n = 1094) from four cruises (M135-M138) in the Eastern Tropical South Pacific (ETSP) to evaluate dNi dynamics under variable biogeochemical conditions in a highly productive shelf region. We additionally report total and labile particulate Ni concentrations along two cross-shelf sections at 16° S and 17° S. The ETSP features a productive Eastern Boundary Upwelling System along the Peruvian-Chilean shelf. This coincides with an extensive underlying Oxygen Minimum Zone which leads to persistently high phosphate and intermittently high Fe conditions.</div><div>The vast majority of dNi concentrations measured across the Peruvian shelf were within the range 2.2–10.8 nM dNi with highly reproducible depth profiles compared to prior cruises in different seasons, years, and El Niño–Southern Oscillation phases. Evidence of lower dNi concentrations was only found at one inshore location with dNi as low as 1.3 nM. Such low dNi concentrations appear to be rare. Whilst biogenic Ni associated with diatom detritus is buried in Peruvian shelf sediments, biological dNi demand on the Peruvian shelf is <30 % of the annual upwelled dNi flux and burial in shelf sediments accounts for approximately 1–3 % of the upwelled dNi flux. Total particulate Ni concentrations measured on two cross-shelf sections ranged from below detection to 1.2 nM and were consistently low relative to dNi concentrations. On average, total particulate Ni (TpNi) was 2.6 % of dNi + TpNi with labile particulate Ni (LpNi) and TpNi remaining tightly coupled (R<sup>2</sup> = 0.99). As is the case elsewhere in the global ocean, dNi remained tightly correlated with phosphate and silicic acid concentrations. Limited biological demand for Ni relative to the upwelled dNi supply explains why dNi profiles in general were quite homogenous across the Peruvian coastal, shelf and offshore regions. Finally, profiles of dNi suggested a slightly lower than average dNi:phosphorous ratio (0.673 mmol (mol P)<sup>−1</sup>) in the upper water column. Similar distributions of dNi and dNi:phosphorous ratios were found for the Benguela and Mauritania shelves reinforcing the relatively invariable nature of dNi profiles even in extremely productive shelf environments.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105531"},"PeriodicalIF":3.0,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889522","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 : 2025-08-14DOI: 10.1016/j.dsr2.2025.105530
Sonia Yáñez , Pamela Hidalgo , Paula Ruz-Moreno , Kam W. Tang
Traditional field sampling assumes all zooplankton collected are originally alive, but ignoring even a small percentage of dead zooplankton can result in large errors in predicting population dynamics and secondary production. We tested a protocol for Neutral Red staining and live/dead sorting of zooplankton samples from upwelling zones within the Humboldt Current System. In laboratory tests, live individuals of diverse copepod species including eggs, naupliar and advanced stages, as well as several gelatinous zooplankton groups, were stained readily and the staining efficiency was better than 94.6 %. Larval fish and crabs were only weakly stained. Once validated, we applied the staining method in field sampling in Mejillones Bay and Concepcion during upwelling and downwelling periods. Both abundances and percentages of zooplankton carcasses were significantly higher during upwelling events, and carcasses were mostly concentrated within the Oxygen Minimum Zone, suggesting that intrusion of oxygen-poor water during upwelling led to higher non-predatory mortality especially among species sensitive to hypoxia. Carcass abundances also varied between developmental stages, likely a result of differences in low-oxygen tolerance as well as in situ abundances between stages. Incorporation of Neutral Red staining method into routine sampling will generate live/dead zooplankton distribution data that will improve understanding of zooplankton population dynamics, secondary production, trophic link to fisheries, and zooplankton responses to environmental changes.
{"title":"Live and dead zooplankton distributions within the Humboldt current system during upwelling and downwelling events","authors":"Sonia Yáñez , Pamela Hidalgo , Paula Ruz-Moreno , Kam W. Tang","doi":"10.1016/j.dsr2.2025.105530","DOIUrl":"10.1016/j.dsr2.2025.105530","url":null,"abstract":"<div><div>Traditional field sampling assumes all zooplankton collected are originally alive, but ignoring even a small percentage of dead zooplankton can result in large errors in predicting population dynamics and secondary production. We tested a protocol for Neutral Red staining and live/dead sorting of zooplankton samples from upwelling zones within the Humboldt Current System. In laboratory tests, live individuals of diverse copepod species including eggs, naupliar and advanced stages, as well as several gelatinous zooplankton groups, were stained readily and the staining efficiency was better than 94.6 %. Larval fish and crabs were only weakly stained. Once validated, we applied the staining method in field sampling in Mejillones Bay and Concepcion during upwelling and downwelling periods. Both abundances and percentages of zooplankton carcasses were significantly higher during upwelling events, and carcasses were mostly concentrated within the Oxygen Minimum Zone, suggesting that intrusion of oxygen-poor water during upwelling led to higher non-predatory mortality especially among species sensitive to hypoxia. Carcass abundances also varied between developmental stages, likely a result of differences in low-oxygen tolerance as well as <em>in situ</em> abundances between stages. Incorporation of Neutral Red staining method into routine sampling will generate live/dead zooplankton distribution data that will improve understanding of zooplankton population dynamics, secondary production, trophic link to fisheries, and zooplankton responses to environmental changes.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105530"},"PeriodicalIF":3.0,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893005","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 : 2025-08-13DOI: 10.1016/j.dsr2.2025.105529
Amir Ghazilou
The Persian Gulf forms a natural geographic barrier to coral reef communities. This study employs MaxEnt modeling with environmental data from Bio-ORACLE to assess the potential distributions of coral/algae and microalgal mats under present conditions and future (2090–2100) scenarios for SSP1, SSP3, and SSP5. Maximum temperature and mixed layer depth were found as the key environmental variables defining habitat suitability. Present-day suitable habitat for coral/algae totals approximately 94,161 km2. Under SSP1, a moderate decline of 2.29 % (to ∼92,002 km2) in habitat area is projected. SSP3 scenario shows an increase of 14.32 % (up to ∼107,651 km2), potentially due to local adaptation. In comparison, SSP5 projects a severe 18.14 % decrease (∼77,072 km2) with fragmentation and isolation characterized by a 40 % drop in effective mesh size and 130 % increase in edge density. Microalgal mats exhibited an increasing area and connectivity under more severe scenarios, with the total core area rising from ∼5.2 million to over 16.7 million square units. The largest patch index exceeded 82 %, and the aggregation index peaked near 95 %. Biotic velocity metrics suggested that microalgal mats require movements exceeding 1400 m/year, which is higher than those of coral/algae. North-south direction dominates patterns of change in distribution. These results underscore the need for targeted conservation that prioritizes connectivity and scenario-sensitive management actions in response to climate change in the Persian Gulf.
{"title":"MaxEnt modeling for predicting the present-day and future potential geographical distribution of coral/algae in the Persian Gulf under climate change","authors":"Amir Ghazilou","doi":"10.1016/j.dsr2.2025.105529","DOIUrl":"10.1016/j.dsr2.2025.105529","url":null,"abstract":"<div><div>The Persian Gulf forms a natural geographic barrier to coral reef communities. This study employs MaxEnt modeling with environmental data from Bio-ORACLE to assess the potential distributions of coral/algae and microalgal mats under present conditions and future (2090–2100) scenarios for SSP1, SSP3, and SSP5. Maximum temperature and mixed layer depth were found as the key environmental variables defining habitat suitability. Present-day suitable habitat for coral/algae totals approximately 94,161 km<sup>2</sup>. Under SSP1, a moderate decline of 2.29 % (to ∼92,002 km<sup>2</sup>) in habitat area is projected. SSP3 scenario shows an increase of 14.32 % (up to ∼107,651 km<sup>2</sup>), potentially due to local adaptation. In comparison, SSP5 projects a severe 18.14 % decrease (∼77,072 km<sup>2</sup>) with fragmentation and isolation characterized by a 40 % drop in effective mesh size and 130 % increase in edge density. Microalgal mats exhibited an increasing area and connectivity under more severe scenarios, with the total core area rising from ∼5.2 million to over 16.7 million square units. The largest patch index exceeded 82 %, and the aggregation index peaked near 95 %. Biotic velocity metrics suggested that microalgal mats require movements exceeding 1400 m/year, which is higher than those of coral/algae. North-south direction dominates patterns of change in distribution. These results underscore the need for targeted conservation that prioritizes connectivity and scenario-sensitive management actions in response to climate change in the Persian Gulf.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105529"},"PeriodicalIF":3.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841760","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 : 2025-08-08DOI: 10.1016/j.dsr2.2025.105525
Alvaro Romo , Cristina Gutiérrez-Zárate , Meri Bilan , Andrea Gori , Alfredo Veiga , Rodrigo Pérez , Maria Rakka , António Godinho , Timm Schoening , Andrew Carey , Marina Carreiro-Silva , Covadonga Orejas
Three-dimensional photogrammetry is a method used to measure 3D reconstructions created from 2D images. The precision of this method makes it widely used for studying ecosystem engineers such as corals. Although photogrammetry has been used to study both tropical and cold-water corals in situ, very few studies, with certain limitations including potential coral stress or low replicability, use photogrammetry to study corals in aquaria. For accurate 3D photogrammetric measurements of corals under laboratory conditions, we present the “Coruña 3D system” and the two prototypes that served as input for the development of the final setup. The “Coruña 3D system” is presented as a publicly accessible cost-effective setup used to obtain a complete set of images of a coral in an aquarium and create accurate 3D reconstructions. Using photogrammetry to study corals in aquaria enables the measurement and monitoring of different variables over both, short and long periods of time. The effectiveness of the system was assessed with a total of 120 3D reconstructions of cold-water corals. The system has resulted in a highly accurate tool, creating 3D reconstructions with a total scale error of 0.048 ± 0.079 mm (mean ± SD). Moreover, this open-source, cost-effective (<3000 €) system provided precise results overcoming the limitations of previous prototypes and mechanisms used in other studies. The adaptability of the "Coruña 3D system" according to the needs of the study makes it a versatile and useful tool to measure corals as well as other benthic marine species.
{"title":"A cost-effective, open-source laboratory system for 3D photogrammetric analysis of corals","authors":"Alvaro Romo , Cristina Gutiérrez-Zárate , Meri Bilan , Andrea Gori , Alfredo Veiga , Rodrigo Pérez , Maria Rakka , António Godinho , Timm Schoening , Andrew Carey , Marina Carreiro-Silva , Covadonga Orejas","doi":"10.1016/j.dsr2.2025.105525","DOIUrl":"10.1016/j.dsr2.2025.105525","url":null,"abstract":"<div><div>Three-dimensional photogrammetry is a method used to measure 3D reconstructions created from 2D images. The precision of this method makes it widely used for studying ecosystem engineers such as corals. Although photogrammetry has been used to study both tropical and cold-water corals in situ, very few studies, with certain limitations including potential coral stress or low replicability, use photogrammetry to study corals in aquaria. For accurate 3D photogrammetric measurements of corals under laboratory conditions, we present the “Coruña 3D system” and the two prototypes that served as input for the development of the final setup. The “Coruña 3D system” is presented as a publicly accessible cost-effective setup used to obtain a complete set of images of a coral in an aquarium and create accurate 3D reconstructions. Using photogrammetry to study corals in aquaria enables the measurement and monitoring of different variables over both, short and long periods of time. The effectiveness of the system was assessed with a total of 120 3D reconstructions of cold-water corals. The system has resulted in a highly accurate tool, creating 3D reconstructions with a total scale error of 0.048 ± 0.079 mm (mean ± SD). Moreover, this open-source, cost-effective (<3000 €) system provided precise results overcoming the limitations of previous prototypes and mechanisms used in other studies. The adaptability of the \"Coruña 3D system\" according to the needs of the study makes it a versatile and useful tool to measure corals as well as other benthic marine species.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105525"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912276","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}
This study evaluates the hydrodynamic and tidal dynamics of the Persian Gulf using the Finite Volume Community Ocean Model (FVCOM) under two distinct forcing configurations: wind-and-tide and tide-only. A comprehensive statistical assessment was conducted to validate the model's performance in replicating tidal elevation and flow velocity against in-situ data as well as TPXO10 tidal predictions. Co-tidal maps revealed that semi-diurnal constituents (e.g., M2, S2) exhibit pronounced phase transitions, particularly at the Strait of Hormuz, highlighting the influence of regional bathymetry on tidal propagation. Diurnal constituents (e.g., K1, O1) showed more uniform phase distributions, suggesting reduced sensitivity to topographic constraints. The analysis of tidal amplitudes underscored the dominance of the M2 and K1 constituents. Vertical analyses of current speeds revealed distinct patterns of tidal attenuation between diurnal and semi-diurnal constituents. The diurnal constituents undergo greater amplitude reductions with depth compared to semi-diurnal constituents, indicating stronger bottom interaction processes for longer-period tides. While the M2 constituent demonstrated minimal sensitivity to wind forcing, diurnal constituents like K1 showed significant attenuation influenced by seasonal stratification and atmospheric conditions. These findings underscore the critical interplay between wind forcing, tidal dynamics, and seasonal variability in shaping the hydrodynamics of the Persian Gulf.
{"title":"The vertical profiles of the tidal constituents and bed-induced dissipation of tidal signals in the Persian Gulf","authors":"Morteza Keshtgar , Seyed Mostafa Siadatmousavi , Jafar Azizpour","doi":"10.1016/j.dsr2.2025.105528","DOIUrl":"10.1016/j.dsr2.2025.105528","url":null,"abstract":"<div><div>This study evaluates the hydrodynamic and tidal dynamics of the Persian Gulf using the Finite Volume Community Ocean Model (FVCOM) under two distinct forcing configurations: wind-and-tide and tide-only. A comprehensive statistical assessment was conducted to validate the model's performance in replicating tidal elevation and flow velocity against in-situ data as well as TPXO10 tidal predictions. Co-tidal maps revealed that semi-diurnal constituents (e.g., M2, S2) exhibit pronounced phase transitions, particularly at the Strait of Hormuz, highlighting the influence of regional bathymetry on tidal propagation. Diurnal constituents (e.g., K1, O1) showed more uniform phase distributions, suggesting reduced sensitivity to topographic constraints. The analysis of tidal amplitudes underscored the dominance of the M2 and K1 constituents. Vertical analyses of current speeds revealed distinct patterns of tidal attenuation between diurnal and semi-diurnal constituents. The diurnal constituents undergo greater amplitude reductions with depth compared to semi-diurnal constituents, indicating stronger bottom interaction processes for longer-period tides. While the M2 constituent demonstrated minimal sensitivity to wind forcing, diurnal constituents like K1 showed significant attenuation influenced by seasonal stratification and atmospheric conditions. These findings underscore the critical interplay between wind forcing, tidal dynamics, and seasonal variability in shaping the hydrodynamics of the Persian Gulf.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105528"},"PeriodicalIF":3.0,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144826357","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}
The south-eastern Arabian Sea (SEAS) witnesses the confluence of the Arabian Sea and the Bay of Bengal waters along with an influence from both the summer and winter monsoon. As a result, the distinct hydrographic parameters are expected to modulate the diversity and abundance of planktic foraminifera in this region. Hence, 91 surface sediment samples covering a depth range from 25 m to 3150 m were analysed to establish region-specific planktic foraminiferal ecology. Overall, the water depth, seasonal chlorophyll-a and the mixed layer parameters significantly influence the planktic foraminiferal abundance in the SEAS. A total of 31 species of planktic foraminifera belonging to 17 genera were found. We report Globigerina bulloides as the most dominant species, preferring high productivity regions. Globigerina bulloides and Globigerinoides ruber exhibited opportunistic distribution patterns while region-specific preferences were observed for Globigerinita glutinata, N. dutertrei, Globorotalia cultrata and Trilobatus sacculifer. Globigerinita glutinata show a restricted seasonal occurrence while G. hexagonus is reported as a ubiquitous species. The ecological preferences of the planktic foraminifera inferred from the SEAS will help in reconstructing the past climatic conditions from this region.
{"title":"Assessing the ecological preferences of planktic foraminifera from the south-eastern Arabian Sea","authors":"Kumari Anjali , Thejasino Suokhrie , Rajeev Saraswat , Sujata R. Kurtarkar , Dinesh Kumar Naik , Dharmendra Pratap Singh , Rupal Dubey","doi":"10.1016/j.dsr2.2025.105527","DOIUrl":"10.1016/j.dsr2.2025.105527","url":null,"abstract":"<div><div>The south-eastern Arabian Sea (SEAS) witnesses the confluence of the Arabian Sea and the Bay of Bengal waters along with an influence from both the summer and winter monsoon. As a result, the distinct hydrographic parameters are expected to modulate the diversity and abundance of planktic foraminifera in this region. Hence, 91 surface sediment samples covering a depth range from 25 m to 3150 m were analysed to establish region-specific planktic foraminiferal ecology. Overall, the water depth, seasonal chlorophyll-a and the mixed layer parameters significantly influence the planktic foraminiferal abundance in the SEAS. A total of 31 species of planktic foraminifera belonging to 17 genera were found. We report <em>Globigerina bulloides</em> as the most dominant species, preferring high productivity regions. <em>Globigerina bulloides</em> and <em>Globigerinoides ruber</em> exhibited opportunistic distribution patterns while region-specific preferences were observed for <em>Globigerinita glutinata, N. dutertrei, Globorotalia cultrata</em> and <em>Trilobatus sacculifer. Globigerinita glutinata</em> show a restricted seasonal occurrence while <em>G. hexagonus</em> is reported as a ubiquitous species. The ecological preferences of the planktic foraminifera inferred from the SEAS will help in reconstructing the past climatic conditions from this region.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105527"},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864097","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}
The World Coral Conservatory (WCC) has initiated a pioneering global biobank to conserve coral species in response to accelerating reef degradation. This paper reports on the first coral collection mission at Aldabra Atoll, Seychelles, undertaken during the Monaco Explorations Indian Ocean expedition in October 2022. Fifty-eight colonies, representing 21 species, were successfully collected, transported, and distributed across European aquariums. We detail the methodologies for coral collection, transport, and in-tank maintenance, ensuring genetic diversity and coral health preservation.
Post-arrival monitoring revealed an 88 % survival rate over an 18-months period, despite challenges such as bleaching and bacterial infections. The success of this mission validates the feasibility of long-term coral conservation in aquaria and sets the stage for future expeditions and advanced genetic research.
{"title":"Establishment of a Global Coral Biobank: Implementation of the protocols from coral collection to long distance shipping and long-term maintenance in public aquariums","authors":"Olivier Brunel , Dominique Barthelemy , Max Janse , Renaud Herbert , Nienke Klerks , Maureen Midol , Bruno Piguet , Christophe Cavelli , Silvia Vimercati , Frauke Fleischer-Dogley , Annabelle Constance , Didier Zoccola","doi":"10.1016/j.dsr2.2025.105516","DOIUrl":"10.1016/j.dsr2.2025.105516","url":null,"abstract":"<div><div>The World Coral Conservatory (WCC) has initiated a pioneering global biobank to conserve coral species in response to accelerating reef degradation. This paper reports on the first coral collection mission at Aldabra Atoll, Seychelles, undertaken during the Monaco Explorations Indian Ocean expedition in October 2022. Fifty-eight colonies, representing 21 species, were successfully collected, transported, and distributed across European aquariums. We detail the methodologies for coral collection, transport, and in-tank maintenance, ensuring genetic diversity and coral health preservation.</div><div>Post-arrival monitoring revealed an 88 % survival rate over an 18-months period, despite challenges such as bleaching and bacterial infections. The success of this mission validates the feasibility of long-term coral conservation in aquaria and sets the stage for future expeditions and advanced genetic research.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105516"},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889523","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}