Marine Carbon Biogeochemistry

This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed

Marine Carbon Biogeochemistry

This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed

Nutritional importance of benthic bacteria for deep-sea nematodes from the Arctic ice margin: Results of an isotope tracer experiment

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Identifiability and uncertainty analysis of bio-irrigation rates

Bio-irrigation is often quantified through incubations where an inert tracer is added to the overlying water of a core or a benthic chamber, and subsequently following the tracer distribution in either the overlying water or the porewater. The interpretation is based on fitting data with a model containing several unknown parameters such as the enhancement over molecular diffusion or non-local exchange. In this paper, we test under what conditions the results obtained through this fitting are robust. We first use identifiability analysis to investigate the minimum data requirements for two types of sediments, representative for deep-sea and shallow-water settings. We then use two different representative data-sets to estimate uncertainties of the fitted parameters, based on a Bayesian technique, the Markov Chain Monte Carlo. Using only the concentration change in the overlying water, it is not possible to constrain both the rate and the mechanism of bio-irrigation, thus, sampling the porewaters at the end of the incubation is a necessity

Major role of marine vegetation on the oceanic carbon cycle

The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests) to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tmol C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of about 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down re-calculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 216 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contributes about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3388 Tg C y -1, suggesting that bulk of the benthic net ecosystem production must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 1126 to 3534 Tg C y -1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg Cy-1, identifying the destruction of these ecosystems as an important loss of CO2 sink capacity in the biosphere.Peer Reviewe

A Bayesian compositional estimator for microbial taxonomy based on biomarkers

Determination of microbial taxonomy based on lipid or pigment spectra requires use of a compositional estimator. We present a new approach based on Bayesian inference and an implementation in the open software platform R. The Bayesian Compositional Estimator (BCE) aims not only to obtain a maximum likelihood solution, but also to provide a complete estimate of the taxonomic composition, including probability distributions and dependencies between estimated values. BCE results are compared with those obtained with CHEMTAX. The BCE has not only a similar accuracy, but also extracts more information from the data, the most obvious being standard deviation and covariance estimates

Potential uptake of dissolved organic matter by seagrasses and macroalgae

Dissolved organic nitrogen (DON) acts as a large reservoir of fixed nitrogen. Whereas DON utilization is common in the microbial community, little is known about utilization by macrophytes. We investigated the ability of the coexisting temperate marine macrophytes Zostera noltii, Cymodocea nodosa, and Caulerpa prolifera to take up nitrogen and carbon from small organic substrates of different molecular complexities (urea, glycine, L-leucine, and L-phenylalanine) and from dissolved organic matter (DOM) derived from algal and bacterial cultures (substrates with a complex composition). In addition to inorganic nitrogen, nitrogen from small organic substrates could be taken up in significant amounts by all macrophytes. Substrate uptake by the aboveground tissue differed from that of the belowground tissue. No relationships between carbon and nitrogen uptake of small organics were found. The preference for individual organic substrates was related to their structural complexity and C:N ratio. Uptake of algae-derived organic nitrogen was of similar magnitude as inorganic nitrogen, and was preferred over bacteria-derived nitrogen. These results add to the growing evidence that direct or quick indirect DON utilization may be more widespread among aquatic macrophytes than traditionally thought.This research was supported by the regional government of Andalusia project FUNDIV (P07-RNM-2516), the Spanish Project CTM2008-00012/MAR, a European Reintegration Grant (MERG-CT-2007-205675), a travel grant from Schure-Beijerinck-Popping Fund (SBP/JK/2007-32) and the Netherlands Organization for Scientific Research. Thanks to Fidel Echevarrìa Navas (Director of CACYTMAR) for granting us access to facilities, and to Bas Koutstaal for helping with sample processing. We also thank the anonymous reviewers for their valuable comments which significantly improved this manuscript

Вимоги до матеріалів, що приймаються до друку в збірнику наукових праць "Cучасна українська політика. Політики і політологи про неї"

We investigated the temporal variation of pelagic and benthic food sources in the diet of benthic taxa at a depositional site in the Southern Bight of the North Sea by means of fatty acid (FA) biomarkers and compound-specific stable isotope analysis (CSIA). The taxa were the non-selective deposit feeding nematodes (<em>Sabatieria</em> spp. and ‘other nematodes’), and three dominant macrobenthic species: two true suspension-deposit feeders (the bivalve <em>Abra alba</em> and the tube dwelling polychaete <em>Owenia fusiformis</em>) and the suspected predatory mud-dwelling anemone <em>Sagartia</em> sp. These species make up on average 16% (<em>Abra alba</em>), 17% (<em>Sagartia</em> sp.) and 20% (<em>Owenia fusiformis</em>) of the biomass in the <em>Abra alba–Kurtiella bidentata</em> community in this area. Phytoplankton dynamics in the suspended particulate matter of the water column as inferred from cell counts, chlorophyll-<em>a</em> and organic carbon content were clearly visible in sediment and animal FA abundance as well, whereas phytodetritus dynamics in the sediment FA composition were less clear, probably due to patchy distribution or stripping of FA by macrofauna. Nematodes appeared to assimilate mainly Polyunsaturated Fatty Acids (PUFAs) from their sedimentary environment and were further non-selectively accumulating more (<em>Sabatieria</em> spp.) or less (‘other nematodes’) FA from the deposited phytodetritus. In contrast, <em>Abra alba</em> FA composition was consistent with a diatom-dominated diet and consumption of <em>Phaeocystis</em> was observed in <em>Owenia fusiformis,</em> whereas <em>Sagartia</em> sp. showed evidence of a predatory behaviour. While the total FA content in <em>Owenia fusiformis</em> remained constant throughout the year, <em>Sagartia</em> sp. doubled and <em>Abra alba</em> increased its FA level more than 10-fold in response to the organic matter deposition from the phytoplankton bloom. This leads to the conclusion that there is no resource partitioning between non-selective deposit feeding nematodes and the suspension-deposit feeding macrobenthic organisms, suggesting they belong to separate parts of the benthic food web