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Optimal timing of multiple investment decisions in a wood value chain: A real options approach
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RBINS Staff Publications 2021
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Optimization and quality control of suspended particulate matter concentration measurement using turbidity measurements
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The dry weight concentration of suspended particulate material, [SPM] (units: mg L-1), is measured by passing a known volume of seawater through a preweighed filter and reweighing the filter after drying. This is apparently a simple procedure, but accuracy and precision of [SPM] measurements vary widely depending on the measurement protocol and experience and skills of the person filtering. We show that measurements of turbidity, T (units: FNU), which are low cost, simple, and fast, can be used to optimally set the filtration volume, to detect problems with the mixing of the sample during subsampling, and to quality control [SPM]. A relationship between T and `optimal filtration volume', V opt, is established where V opt is the volume at which enough matter is retained by the filter for precise measurement, but not so much that the filter clogs. This relationship is based on an assessment of procedural uncertainties in the [SPM] measurement protocol, including salt retention, filter preparation, weighing, and handling, and on a value for minimum relative precision for replicates. The effect of filtration volume on the precision of [SPM] measurement is investigated by filtering volumes of seawater ranging between one fifth and twice V opt. It is shown that filtrations at V opt maximize precision and cost effectiveness of [SPM]. Finally, the 90\% prediction bounds of the T versus [SPM] regression allow the quality control of [SPM] determinations. In conclusion it is recommended that existing [SPM] gravimetric measurements be refined to include measurement of turbidity to improve their precision and quality control.
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RBINS Staff Publications
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Ore Deposits: Origin, Exploration, and Exploitation
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RBINS Staff Publications 2019
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Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)
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RBINS Staff Publications
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Organic carbon accumulation and productivity over the past 130 years in Lake Kawaguchi (central Japan) reconstructed using organic geochemical proxies.
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RBINS Staff Publications 2020
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Organic Matter Composition of Biomineral flocs and Its Influence on Suspended Particulate Matter Dynamics Along a Nearshore to Offshore Transect
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The seasonal variation in concentration of transparent exopolymer particles (TEPs), particulate organic carbon (POC) and particulate organic nitrogen (PON) were investigated together with floc size and the concentration of suspended particulate matter (SPM) along the cross-shore gradient, from the high turbid nearshore toward the low-turbid offshore waters in the Southern Bight of the North Sea. Our data demonstrate that biophysical flocculation cannot be explained by these heterogeneous parameters, but requires a distinction between a more reactive labile (“fresh”) and a less reactive refractory (“mineral-associated”) fraction. Based on all data, we separated the labile and mineral-associated POC, PON, and TEP using a semi-empirical model approach. The model's estimates of fresh and mineral-associated organic matter (OM) show that great parts of the POC, PON, and TEP are associated with suspended minerals, which are present in the water column throughout the year, whereas the occurrence of fresh TEP, POC, and PON is restricted to spring and summer months. In spite of a constantly high abundance of total TEP throughout the entire year, it is its fresh fraction that promotes the formation of larger and faster sinking biomineral flocs, thereby contributing to reducing the SPM concentration in the water column over spring and summer. Our results show that the different components of the SPM, such as minerals, extracellular OM and living organisms, form an integrated dynamic system with direct interactions and feedback controls.
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RBINS Staff Publications 2022
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Organic Matter Composition of Biomineral Flocs and Its Influence on Suspended Particulate Matter Dynamics Along a Nearshore to Offshore Transect
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The seasonal variation in concentration of transparent exopolymer particles (TEPs), particulate organic carbon (POC) and particulate organic nitrogen (PON) were investigated together with floc size and the concentration of suspended particulate matter (SPM) along the cross-shore gradient, from the high turbid nearshore toward the low-turbid offshore waters in the Southern Bight of the North Sea. Our data demonstrate that biophysical flocculation cannot be explained by these heterogeneous parameters, but requires a distinction between a more reactive labile (“fresh”) and a less reactive refractory (“mineral-associated”) fraction. Based on all data, we separated the labile and mineral-associated POC, PON, and TEP using a semi-empirical model approach. The model's estimates of fresh and mineral-associated organic matter (OM) show that great parts of the POC, PON, and TEP are associated with suspended minerals, which are present in the water column throughout the year, whereas the occurrence of fresh TEP, POC, and PON is restricted to spring and summer months. In spite of a constantly high abundance of total TEP throughout the entire year, it is its fresh fraction that promotes the formation of larger and faster sinking biomineral flocs, thereby contributing to reducing the SPM concentration in the water column over spring and summer. Our results show that the different components of the SPM, such as minerals, extracellular OM and living organisms, form an integrated dynamic system with direct interactions and feedback controls.
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RBINS Staff Publications 2022
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Organizing large-scale biodiversity inventories in the tropics: lessons from IBISCA projects
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Leponce, M.1, Pascal, O.2, Novotny, V.3,4 & Y. Basset5 (1) Royal Belgian Institute of Natural Sciences, Belgium (Maurice.Leponce@naturalsciences.be); (2) Pro-Natura International, France; (3) University of South Bohemia, Czech Rep.; (4) Czech Academy of Sciences; (5) Smithsonian Tropical Research Institute, Republic of Panama. Background: IBISCA is an international and informal network of biodiversity experts conducting large-scale biotic inventories in various regions of the World (www.ibisca.net). Each IBISCA project is a collective effort addressing a global ecological question. IBISCA-Panama (2003-2004) aimed at estimating the overall arthropod diversity of a lowland rainforest while the Papua New Guinea survey (2012-2014), conducted in the framework of the “Our Planet Reviewed” programme, aimed at assessing the diversity generated by the elevational factor, from sea level up to the tree line. Methods: All projects are multi-taxa (with an emphasis on plants and arthropods), multi-strata and multi-methods. A central database (DB) is at the heart of each project. Results: The data flow follows a 10 step standard process: (1) sampling design which is often a trade-off between sampling effort and representativeness; (2) pre-printing of permanent labels with unique codes for samples and specimens; (3) collection of specimens with standardized mass collection methods; (4) on-site pre-sorting of material by helpers (para-taxonomists, students) to Order level; (5) further sorting to Family level by Taxonomic Working Group (TWIG) leaders and dispatching of specimens to experts; (6) identification of the material to (morpho-)species level by taxonomic experts who send afterwards the results to their TWIG leader; (7) control of the quality of data by TWIG leaders who fill a data entry template and send it to the database administrator; (8) import and cleaning of the data by the database administrator; (9) analysis and publication of the data by participants, either collectively or individually; (10) export of the DB to a public repository of data. Assisted data entry with high tech equipment (barcode scanner, PDA) reduces the risk of errors. Discussion/conclusion: Our experience shows that the main bottleneck in the data flow is the processing of the huge quantity of specimens collected. Solutions include securing enough funds for this critical step, training research technicians (para-taxonomists/ecologists) to assist main investigators and focusing on a limited number of informative yet tractable taxa. An additional benefit is that providing employment to local research assistants supports initiatives of local communities to conserve their forests.
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RBINS Staff Publications 2017
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Organizing large-scale inventories of biodiversity in the tropics: the genesis and lessons of the project Our Planet Reviewed Papua New Guinea – land component
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RBINS Staff Publications 2020
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Origin and patterns of biodiversity of subterranean aquatic Clitellata
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Subterranean ecosystem biodiversity is characterized by a unique combination of four features that may account for its patterns and fluctuations at a global scale: (1) a low number of lineages due to environmental harshness, (2) a high proportion of endemic species as a result of habitat fragmentation and isolation, (3) a high level of relict taxa, best explained by the relative stability and antiquity of the habitat compared with most superficial habitats, and (4) food webs that are truncated at both the bottom (no primary producers) and the top (few or no predators and no specialized ones). In this review, we present a synthesis of the current state of knowledge of groundwater oligochaetes, and we investigate in what extent their biodiversity meets these criteria. The present knowledge is strongly biased in favour of the West-Palaearctic region, in particular the karst of Southern Europe. While our understanding of groundwater biodiversity in Europe and the United States has gained much during these last decades, many areas are undersampled in the world. To date, more than 300 nominal species have been found in ground waters all over the world (on about 1,700 and 1,100 aquatic and freshwater oligochaete species, respectively). Most of these species should be considered as incidentals or waifs; however, about one-third of them are found exclusively in this environment (stygobionts). Among the 21 families that are fully aquatic or include species occurring in aquatic habitats, 16 families are present in ground water. Stygobiont species belong to only 7 different families, harbouring 42 genera among which 17 are represented by a single species. Thirty-four per cent of the species are representatives of only two genera: Trichodrilus (Lumbriculidae) and Rhyacodrilus (Naididae). With 9 species, all being stygobiont, the Parvidrilidae is unique in being the only family, worldwide, comprising taxa that are restricted to groundwater habitats. Data on the distribution of stygobiont oligochaetes suggest pronounced endemism, nearly 60% of the species being known only from their type locality. The origins of subterranean oligochaete biodiversity probably involve multiple and successive colonization processes, both from marine and freshwater environments. The current distribution of Parvidrilidae, Rhyacodriloides (Rhyacodriloidinae), Delaya (Haplotaxidae), or species belonging to primarily marine genera, may be explained when assuming that these species are palaeoendemics or relicts, namely survivors of an old fauna that has long since become extinct in the surrounding areas. Aquatic oligochaetes appear to be pre-adapted to live in the subterranean environment. In the absence of genuine troglomorphic characters, their stygobiotic status can only be inferred from their exclusive presence in the subterranean environment. Valuable studies to enhance knowledge of subterranean aquatic oligochaetes will probably take more advantage of investigating adaptations that enable them to face scarceness of food and oxygen in groundwater, rather than focussing on an uncertain quest for morphological adaptations. Promising approaches would be to compare related hypogean and epigean species within the same genus, such as in Trichodrilus and Rhyacodrilus, or ecosystems the most similar to the underground such as lake hypolimnia and the deep sea. Keywords: ground water, Clitellata, biodiversity, patterns, endemism, relictuality, adaptation.
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