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Oceanography

Oceanography encompasses many diverse disciplines, relating to the physical, chemical and biological processes which occur in the Earth’s oceans. Stable isotope analysis provides a powerful means to trace these processes, both modern and ancient; palaeoceangraphy uses oxygen stable isotope signatures of materials preserved in ice cores or sediments to elucidate the history of sea-surface or deep sea temperatures. Stable isotopes of oxygen and hydrogen can also reveal the hydrology of oceanic waters, tracing the movement and circulation of waters, evaporitic processes, and meteorological influences on local, regional or global scales.

Nutrient cycling and ecology of the world’s oceans is also of interest; carbon, nitrogen and sulfur stable isotopes are powerful tools which may be deployed to trace algal activity, elucidate food chain structures within surface or benthic communities, and trace fluxes of nutrients throughout the seasons. Stable isotope analysis is particularly useful for exploring the unusual frontiers of deep hydrothermal systems, where unusual chemosynthetic organisms are the lynchpins of the communities which thrive under those extreme conditions.

Oceanography publications using our instrumentation

Our customers use our instruments to do some amazing research in the oceanography application field. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

83 results:

Water cycle and salinity dynamics in the mangrove forests of Europa and Juan de Nova Islands, southwest Indian Ocean
Rapid Communications in Mass Spectrometry (2016)
Luc Lambs, Perrine Mangion, Eric Mougin, François Fromard

Rationale: The functioning of mangrove forests found on small coralline islands is characterized by limited freshwater inputs. Here, we present data on the water cycling of such systems located on Europa and Juan de Nova Islands, Mozambique Channel. Methods: In order to better understand the water cycle and mangrove growth conditions, we have analysed the hydrological and salinity dynamics of the systems by gauge pressure and isotopic tracing (δ18O and δ2H values). Results: Both islands have important seawater intrusion as measured by the water level change and the high salinities in the karstic ponds. Europa Island displays higher salinity stress, with its inner lagoon, but presents a pluri-specific mangrove species formation ranging from shrub to forest stands. No freshwater signal could be detected around the mangrove trees. On Juan de Nova Island, the presence of sand and detrital sediment allows the storage of some amount of rainfall to form a brackish groundwater. The mangrove surface area is very limited with only small mono-specific stands being present in karstic depression. Conclusions: On the drier Europa Island, the salinity of all the water points is equal to or higher than that of the seawater, and on Juan de Nova the groundwater salinity is lower (5 to 20 PSU). This preliminary study shows that the karstic pothole mangroves exist due to the sea connection through the fractured coral and the high tidal dynamics.
Tags: H , O , ge , oc , GH

Records of bulk organic matter and plant pigments in sediment of the “red-tide zone” adjacent to the Changjiang River estuary
Chinese Journal of Oceanology and Limnology (2016)
Zhenjun Kang, Rencheng Yu, Fanzhou Kong, Yunfeng Wang, Yan Gao, Jianhua Chen, Wei Guo, Mingjiang Zhou

Cultural eutrophication caused by nutrient over-enrichment in coastal waters will lead to a cascading set of ecosystem changes and deleterious ecological consequences, such as harmful algal blooms (HABs) and hypoxia. During the past two decades since the late 1990s, recurrent large-scale HABs (red tides) and an extensive hypoxic zone have been reported in the coastal waters adjacent to the Changjiang River estuary. To retrieve the history of eutrophication and its associated ecosystem changes, a sediment core was collected from the “red-tide zone” adjacent to the Changjiang River estuary. The core was dated using the 210Pb radioisotope and examined for multiple proxies, including organic carbon (OC), total nitrogen (TN), stable isotopes of C and N, and plant pigments. An apparent up-core increase of OC content was observed after the 1970s, accompanied by a rapid increase of TN. The concurrent enrichment of δ13C and increase of the C/N ratio suggested the accumulation of organic matter derived from marine primary production during this stage. The accumulation of OC after the 1970s well reflected the significant increase of primary production in the red-tide zone and probably the intensification of hypoxia as well. Plant pigments, including chlorophyll a, β-carotene, and diatoxanthin, showed similar patterns of variation to OC throughout the core, which further confirmed the important contribution of microalgae, particularly diatoms, to the deposited organic matter. Based on the variant profiles of the pigments representative of different microalgal groups, the potential changes of the phytoplankton community since the 1970s were discussed.

Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean
Environmental Research (2016)
Alin C. Dirtu, Govindan Malarvannan, Krishna Das, Violaine Dulau-Drouot, Jeremy J. Kiszka, Gilles Lepoint, Philippe Mongin, Adrian Covaci

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ13C and δ15N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ15N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation.

Patterns in Stable Isotope Values of Nitrogen and Carbon in Particulate Matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras
Frontiers in Marine Science (2016)
Autumn Oczkowski, Betty Kreakie, Richard A. McKinney, Jerry Prezioso

Stable isotope measurements of nitrogen and carbon (δ15N, δ13C) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is critical to interpreting values in these ecosystems. While base-level isotope data are generally readily available for estuaries, nearshore coastal waters, and the open ocean, the continental shelf is less studied. To address this, and as a first step towards developing a surrogate for base-level isotopic signature in this region, we collected surface and deep water samples from the United States’ eastern continental shelf in the Western Atlantic Ocean, from the Gulf of Maine to Cape Hatteras, periodically between 2000 and 2013. During the study, particulate matter δ15N values ranged from 0.8 to 17.4 ‰, and δ13C values from -26.4 to -15.6 ‰ over the region. We used spatial autocorrelation analysis and random forest modeling to examine the spatial trends and potential environmental drivers of the stable isotope values. We observed general trends towards lower values for both nitrogen and carbon isotopes at the seaward edge of the shelf. Conversely, higher δ15N and δ13C values were observed on the landward edge of the shelf, in particular in the southern portion of the sampling area. Across all sites, the magnitude of the difference between the δ15N of subsurface and surface particulate matter (PM) significantly increased with water depth (r2 = 0.41, df = 35, p < 0.001), while δ13C values did not change. There were significant positive correlation between δ15N and δ13C values for surface PM in each of the three marine ecoregions that make up the study area. Stable isotope dynamics on the shelf can inform both nearshore and open ocean research efforts, reflecting regional productivity patterns and, even possibly, large-scale climate fluctuations.

Methane fates in the benthos and water column at cold seep sites along the continental margin of Central and North America
Deep Sea Research Part I: Oceanographic Research Papers (2016)
Roberta L. Hansman, Andrew R. Thurber, Lisa A. Levin, Lihini I. Aluwihare

The potential influence of methane seeps on carbon cycling is a key question for global assessments, but the study of carbon cycling in surface sediments and the water column of cold seep environments is complicated by the high temporal and spatial variability of fluid and gas fluxes at these sites. In this study we directly examined carbon sources supporting benthic and planktonic food webs at venting methane seeps using isotopic and molecular approaches that integrate this variability. At four seep environments located along North and Central America, microorganisms from two size fractions were collected over several days from 2800 to 9050l of seawater to provide a time-integrated measure of key microbial groups and the carbon sources supporting the overall planktonic microbial community. In addition to water column measurements, the extent of seafloor methane release was estimated at two of the sites by examining the stable carbon isotopic signature (δ13C) of benthic metazoan infauna. This signature reveals carbon sources fueling the base of the food chain and thus provides a metric that represents a time-integrated view of the dominant microbial processes within the sediment. The stable carbon isotopic composition of microbial DNA (δ13C-DNA), which had values between −17.0 and −19.5‰, indicated that bulk planktonic microbial production was not ultimately linked to methane or other 13C-depleted seep-derived carbon sources. Instead these data support the importance of organic carbon derived from either photo- or chemoautotrophic CO2 fixation to the planktonic food web. Results of qPCR of microbial DNA sequences coding for a subunit of the particulate methane monooxygenase gene (pmoA) showed that only a small percentage of the planktonic microbial community were potential methane oxidizers possessing pmoA (<5% of 16S rRNA gene copies). There was an overall decrease of 13C-depleted carbon fueling the benthic metazoan community from 3 to 5cm below the seafloor to the sediment surface, reflecting limited use of isotopically depleted carbon at the sediment surface. Rare methane emission as indicated by limited aerobic methane oxidation acts to corroborate our findings for the planktonic microbial community.

The effects of nitrogen pollutants on the isotopic signal (δ15N) of Ulva lactuca: Microcosm experiments
Marine Pollution Bulletin (2016)
Lucia Orlandi, Edoardo Calizza, Giulio Careddu, Pasquale Carlino, Maria Letizia Costantini, Loreto Rossi

Effects of two chemical forms of Nitrogen (NH4+ and NO3−) on δ15N in Ulva lactuca were analysed separately and in mixture at two concentrations. We assessed whether the δ15N values of U. lactuca discriminate between Nitrogen from synthetic fertilisers (inorganic) and from fresh cow manure (organic), and the isotopic ability of the macroalga to reflect Nitrogen concentrations. Isotopic signature and N content of the macroalga reflected different nitrogenous sources and their concentrations after 48h. The inorganic Nitrogen source (NH4NO3) altered the isotopic values of the macroalgae more than Nitrogen from fresh cow manure (NO3−). δ15N values observed in the mixed solution did not differ from those displayed in NH4NO3 treatment alone. We conclude that stable isotope analysis of U. lactuca collected in an unpolluted site and experimentally submerged in sites suspected of being affected by disturbance is a useful tool for rapid monitoring of anthropogenic discharges of Nitrogen pollutants.

Methane fates in the benthos and water column at cold seep sites along the continental margin of Central and North America
Deep Sea Research Part I: Oceanographic Research Papers (2016)
Roberta L. Hansman, Andrew R. Thurber, Lisa A. Levin, Lihini I. Aluwihare

The potential influence of methane seeps on carbon cycling is a key question for global assessments, but the study of carbon cycling in surface sediments and the water column of cold seep environments is complicated by the high temporal and spatial variability of fluid and gas fluxes at these sites. In this study we directly examined carbon sources supporting benthic and planktonic food webs at venting methane seeps using isotopic and molecular approaches that integrate this variability. At four seep environments located along North and Central America, microorganisms from two size fractions were collected over several days from 2800 to 9050l of seawater to provide a time-integrated measure of key microbial groups and the carbon sources supporting the overall planktonic microbial community. In addition to water column measurements, the extent of seafloor methane release was estimated at two of the sites by examining the stable carbon isotopic signature (δ13C) of benthic metazoan infauna. This signature reveals carbon sources fueling the base of the food chain and thus provides a metric that represents a time-integrated view of the dominant microbial processes within the sediment. The stable carbon isotopic composition of microbial DNA (δ13C-DNA), which had values between −17.0 and −19.5‰, indicated that bulk planktonic microbial production was not ultimately linked to methane or other 13C-depleted seep-derived carbon sources. Instead these data support the importance of organic carbon derived from either photo- or chemoautotrophic CO2 fixation to the planktonic food web. Results of qPCR of microbial DNA sequences coding for a subunit of the particulate methane monooxygenase gene (pmoA) showed that only a small percentage of the planktonic microbial community were potential methane oxidizers possessing pmoA (<5% of 16S rRNA gene copies). There was an overall decrease of 13C-depleted carbon fueling the benthic metazoan community from 3 to 5cm below the seafloor to the sediment surface, reflecting limited use of isotopically depleted carbon at the sediment surface. Rare methane emission as indicated by limited aerobic methane oxidation acts to corroborate our findings for the planktonic microbial community.

Seasonal variation in the biochemical compositions of phytoplankton and zooplankton communities in the southwestern East/Japan Sea
Deep Sea Research Part II: Topical Studies in Oceanography (2016)
Naeun Jo, Jae Joong Kang, Won Gyu Park, Bo Ram Lee, Mi Sun Yun, Jang Han Lee, Su Min Kim, Dasom Lee, HuiTae Joo, Jae Hyung Lee, So Hyun Ahn, Sang Heon Lee

The macromolecular composition of phytoplankton communities and the proximate composition of zooplankton communities were measured monthly in the southwestern East/Japan Sea from April to November 2014 in order to identify seasonal changes in, and relationships among, the biochemical compositions in both phytoplankton and zooplankton. The carbohydrate content of phytoplankton was highest in June, whereas the protein content was highest in August and lipids were highest in April. Overall, carbohydrates were dominant (53.2 ± 12.5%) in the macromolecular composition of phytoplankton during the study period. This composition is believed to result from the dominance of diatoms and/or nutrient-depleted conditions. In comparison, the protein level of zooplankton was highest in November, whereas lipids were slightly higher in May than other months. Overall, proteins were the dominant organic compounds (47.9±8.6% DW) in zooplankton communities, whereas lipids were minor components (5.5±0.6% DW). The high protein content of zooplankton might be related to the abundance of copepods, whereas the low lipid content might be due to a relatively high primary production that could provide a sufficient food supply for zooplankton so that they do not require high lipid storage. A significant positive correlation (r=0.971, n=7, p<0.01) was found between the lipid compositions of phytoplankton and zooplankton during our study period with a time lag, which is consistent with the findings from previous studies. More detailed studies on the biochemical composition of phytoplankton and zooplankton are needed to better understand the East/Japan Sea ecosystem's response to the many environmental changes associated with global warming.

The effects of nitrogen pollutants on the isotopic signal (δ15N) of Ulva lactuca: Microcosm experiments
Marine Pollution Bulletin (2016)
Lucia Orlandi, Edoardo Calizza, Giulio Careddu, Pasquale Carlino, Maria Letizia Costantini, Loreto Rossi

Effects of two chemical forms of Nitrogen (NH4+ and NO3−) on δ15N in Ulva lactuca were analysed separately and in mixture at two concentrations. We assessed whether the δ15N values of U. lactuca discriminate between Nitrogen from synthetic fertilisers (inorganic) and from fresh cow manure (organic), and the isotopic ability of the macroalga to reflect Nitrogen concentrations. Isotopic signature and N content of the macroalga reflected different nitrogenous sources and their concentrations after 48h. The inorganic Nitrogen source (NH4NO3) altered the isotopic values of the macroalgae more than Nitrogen from fresh cow manure (NO3−). δ15N values observed in the mixed solution did not differ from those displayed in NH4NO3 treatment alone. We conclude that stable isotope analysis of U. lactuca collected in an unpolluted site and experimentally submerged in sites suspected of being affected by disturbance is a useful tool for rapid monitoring of anthropogenic discharges of Nitrogen pollutants.

Seasonal variation in the biochemical compositions of phytoplankton and zooplankton communities in the southwestern East/Japan Sea
Deep Sea Research Part II: Topical Studies in Oceanography (2016)
Naeun Jo, Jae Joong Kang, Won Gyu Park, Bo Ram Lee, Mi Sun Yun, Jang Han Lee, Su Min Kim, Dasom Lee, HuiTae Joo, Jae Hyung Lee, So Hyun Ahn, Sang Heon Lee

The macromolecular composition of phytoplankton communities and the proximate composition of zooplankton communities were measured monthly in the southwestern East/Japan Sea from April to November 2014 in order to identify seasonal changes in, and relationships among, the biochemical compositions in both phytoplankton and zooplankton. The carbohydrate content of phytoplankton was highest in June, whereas the protein content was highest in August and lipids were highest in April. Overall, carbohydrates were dominant (53.2 ± 12.5%) in the macromolecular composition of phytoplankton during the study period. This composition is believed to result from the dominance of diatoms and/or nutrient-depleted conditions. In comparison, the protein level of zooplankton was highest in November, whereas lipids were slightly higher in May than other months. Overall, proteins were the dominant organic compounds (47.9±8.6% DW) in zooplankton communities, whereas lipids were minor components (5.5±0.6% DW). The high protein content of zooplankton might be related to the abundance of copepods, whereas the low lipid content might be due to a relatively high primary production that could provide a sufficient food supply for zooplankton so that they do not require high lipid storage. A significant positive correlation (r=0.971, n=7, p<0.01) was found between the lipid compositions of phytoplankton and zooplankton during our study period with a time lag, which is consistent with the findings from previous studies. More detailed studies on the biochemical composition of phytoplankton and zooplankton are needed to better understand the East/Japan Sea ecosystem's response to the many environmental changes associated with global warming.