scholarly journals Global nutrient cycling by commercially-targeted marine fish

2021 ◽  
Author(s):  
Priscilla Le Mézo ◽  
Jérôme Guiet ◽  
Kim Scherrer ◽  
Daniele Bianchi ◽  
Eric Galbraith
Keyword(s):  
Nutrient Cycling ◽  
Marine Fish ◽  
Essential Elements ◽  
Global Ocean ◽  
Nutrient Concentrations ◽  
Size Spectrum ◽  
Mesopelagic Fish ◽  
Fish Biomass ◽  
Fishing Activity

Abstract. Throughout the course of their lives fish ingest food containing essential elements, including nitrogen (N), phosphorus (P) and iron (Fe). Some of these elements are retained in the fish body to build new biomass, which acts as a stored reservoir of nutrients, while the rest is excreted or egested, providing a recycling flux to water. Fishing activity has modified the fish biomass distribution worldwide and consequently may have altered fish-mediated nutrient cycling, but this possibility remains largely unassessed, mainly due to the difficulty of estimating global fish biomass and metabolic rates. Here we quantify the role of commercially-targeted marine fish between 10 g and 100 kg () in the cycling of N, P and Fe in the global ocean, and its change due to fishing activity, by using a global size-spectrum model of marine fish populations calibrated to observations of fish catches. Our results show that the amount of nutrients stored in the global pristine , biomass was generally small compared to the ambient surface nutrient concentrations but significant in the nutrient-poor regions of the world: the North Atlantic for P, the oligotrophic gyres for N and the High Nutrient Low Chlorophyll (HNLC) regions for Fe. Similarly, the rate of nutrient removed from the ocean through fishing is globally small compared to the inputs, but can be important locally especially for Fe in the equatorial Pacific and along the western margin of South America and Africa. This model allowed us to compute the spatial distribution of the cycling of elements by the biomass at pristine and global peak catch state, which is relatively small compared to the estimated primary production demand for nutrients and estimated export production of nutrients. Pristine cycling (excretion + egestion) accounted for less than 2.7 % of the primary productivity demand for N, P and Fe globally. Relative to the export of nutrients, modeled global pristine egestion represents on average 2.3 %, 3.0 % and 1.1–22 % for N, P and Fe (low-high estimates), respectively, with a higher fraction in the low-export oligotrophic tropical gyres. Our study highlights the role of the fraction of the icthyosphere (i.e. does not include non-commercial species such as mesopelagic fish) on nutrient storage and cycling, and the potential role of fishing activities on this cycling, which could be of importance in regions of low nutrient concentration, high fish biomass and/or high productivity demand, and especially at the more local scale for Fe.

scholarly journals Examining the Role of Marine Mammals and Seabirds in Southeast Alaska’s Marine Ecosystem Dynamics

2021 ◽  
Vol 8 ◽  
Author(s):  
Melissa Rhodes-Reese ◽  
David Clay ◽  
Curry Cunningham ◽  
Janet Moriles-Miller ◽  
Cheryl Reese ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Fisheries Management ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Marine Ecosystem ◽  
Climatic Conditions ◽  
Ecosystem Dynamics ◽  
Nutrient Concentrations ◽  
Nutrient Sources

Primary producers are the foundation of marine food webs and require reliable nutrient sources to maintain their important role with ecosystems. While marine mammals and seabirds can play critical roles in marine nutrient cycling, their contributions are often overlooked. Southeast Alaska’s marine environment supports abundant marine mammal and seabird populations in addition to valuable fisheries. Nonetheless, there is still relatively little known about nutrient sources and fluxes in this region which is a critical component of fisheries management. The goal of our study was to advance knowledge of the role of mammals and seabirds in marine nutrient cycling and to understand how changing marine mammal and seabird populations may alter ecosystem dynamics. We utilized qualitative network models (QNMs) to examine how a simulated Southeast Alaska ecosystem would respond to an increase in marine mammals, seabirds, and nutrients. Researchers are increasingly utilizing QNMs as a first step in the development of ecosystem-based fisheries management plans as their adaptable nature is well suited to address rapidly changing climatic conditions. Our results indicate that marine mammals and seabirds make important contributions to marine nutrient concentrations in the region and that these valuable ecosystem services should not be overlooked.

Problem of Confidence and its Loss – the Role of a Family in Instilling Truthfulness

2014 ◽  
Vol 4 (2) ◽  
pp. 15-22
Author(s):  
Grzegorz Ignatowski
Keyword(s):  
Close Relationships ◽  
Essential Elements ◽  
Professional Group ◽  
Professional Life ◽  
Personal Life

Abstract Confidence is one of the most essential elements which no social or professional group can exist without. As feature of character it is required in someone’s private, social and professional life. In all our relationships we lose it due to telling lies. Lies accompany our personal life on all its stages. Already three-year old children tell lies to satisfy their parents, check whether they are able to realize they are deceived or to demonstrate their dominance over them. Teachers and ethicists differentiate between useful didactic lies and ruthless and cynical comments harmful to others. Because of emotional ties and close relationships, a family is the best environment where a child should be taught to despise lies and respect trust

Proposal for an IMF Debt Refinancing Subsidiary

2018 ◽  
Keyword(s):  
Developing Country ◽  
Essential Elements ◽  
Acceptable Solution ◽  
Debt Problem ◽  
The Imf

In the chapter, Haq analyses the deepening developing country debt problem of the 1980s and outlines the essential elements for an acceptable solution to the problem. To Haq, IMF seemed to be the most appropriate international intermediary to manage this. Haq goes on to outline the specifics of how the role of the IMF could be modified to find long-term solutions for managing developing-country debt.

GINS: A Global intensifier-based N-Gram sentiment dictionary

2021 ◽  
pp. 1-14
Author(s):  
Hamed Zargari ◽  
Morteza Zahedi ◽  
Marziea Rahimi
Keyword(s):  
Sentiment Analysis ◽  
Essential Elements ◽  
Analysis Methods ◽  
Sentiment Dictionary ◽  
N Gram ◽  
Heterogeneous Effect ◽  
Sentiment Word

Words are one of the most essential elements of expressing sentiments in context although they are not the only ones. Also, syntactic relationships between words, morphology, punctuation, and linguistic phenomena are influential. Merely considering the concept of words as isolated phenomena causes a lot of mistakes in sentiment analysis systems. So far, a large amount of research has been conducted on generating sentiment dictionaries containing only sentiment words. A number of these dictionaries have addressed the role of combinations of sentiment words, negators, and intensifiers, while almost none of them considered the heterogeneous effect of the occurrence of multiple linguistic phenomena in sentiment compounds. Regarding the weaknesses of the existing sentiment dictionaries, in addressing the heterogeneous effect of the occurrence of multiple intensifiers, this research presents a sentiment dictionary based on the analysis of sentiment compounds including sentiment words, negators, and intensifiers by considering the multiple intensifiers relative to the sentiment word and assigning a location-based coefficient to the intensifier, which increases the covered sentiment phrase in the dictionary, and enhanced efficiency of proposed dictionary-based sentiment analysis methods up to 7% compared to the latest methods.

scholarly journals Petrobactin, a siderophore produced by Alteromonas, mediates community iron acquisition in the global ocean

2021 ◽  
Author(s):  
Lauren E. Manck ◽  
Jiwoon Park ◽  
Benjamin J. Tully ◽  
Alfonso M. Poire ◽  
Randelle M. Bundy ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Iron Acquisition ◽  
Biogeochemical Cycling ◽  
Iron Bioavailability ◽  
Siderophore Production ◽  
Global Ocean ◽  
The North ◽  
The North Pacific ◽  
Alteromonas Macleodii

AbstractIt is now widely accepted that siderophores play a role in marine iron biogeochemical cycling. However, the mechanisms by which siderophores affect the availability of iron from specific sources and the resulting significance of these processes on iron biogeochemical cycling as a whole have remained largely untested. In this study, we develop a model system for testing the effects of siderophore production on iron bioavailability using the marine copiotroph Alteromonas macleodii ATCC 27126. Through the generation of the knockout cell line ΔasbB::kmr, which lacks siderophore biosynthetic capabilities, we demonstrate that the production of the siderophore petrobactin enables the acquisition of iron from mineral sources and weaker iron-ligand complexes. Notably, the utilization of lithogenic iron, such as that from atmospheric dust, indicates a significant role for siderophores in the incorporation of new iron into marine systems. We have also detected petrobactin, a photoreactive siderophore, directly from seawater in the mid-latitudes of the North Pacific and have identified the biosynthetic pathway for petrobactin in bacterial metagenome-assembled genomes widely distributed across the global ocean. Together, these results improve our mechanistic understanding of the role of siderophore production in iron biogeochemical cycling in the marine environment wherein iron speciation, bioavailability, and residence time can be directly influenced by microbial activities.

scholarly journals The Role of Averaging for Improving Sea Surface Salinity Retrieval from the Soil Moisture and Ocean Salinity (SMOS) Satellite and Impact of Auxiliary Data

2007 ◽  
Vol 24 (2) ◽  
pp. 255-269 ◽  
Author(s):  
Sabine Philipps ◽  
Christine Boone ◽  
Estelle Obligis
Keyword(s):  
Soil Moisture ◽  
Sensitivity Study ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Global Ocean ◽  
Surface Salinity ◽  
Auxiliary Data ◽  
Additional Information ◽  
Ocean Salinity

Abstract Soil Moisture and Ocean Salinity (SMOS) was chosen as the European Space Agency’s second Earth Explorer Opportunity mission. One of the objectives is to retrieve sea surface salinity (SSS) from measured brightness temperatures (TBs) at L band with a precision of 0.2 practical salinity units (psu) with averages taken over 200 km by 200 km areas and 10 days [as suggested in the requirements of the Global Ocean Data Assimilation Experiment (GODAE)]. The retrieval is performed here by an inverse model and additional information of auxiliary SSS, sea surface temperature (SST), and wind speed (W). A sensitivity study is done to observe the influence of the TBs and auxiliary data on the SSS retrieval. The key role of TB and W accuracy on SSS retrieval is verified. Retrieval is then done over the Atlantic for two cases. In case A, auxiliary data are simulated from two model outputs by adding white noise. The more realistic case B uses independent databases for reference and auxiliary ocean parameters. For these cases, the RMS error of retrieved SSS on pixel scale is around 1 psu (1.2 for case B). Averaging over GODAE scales reduces the SSS error by a factor of 12 (4 for case B). The weaker error reduction in case B is most likely due to the correlation of errors in auxiliary data. This study shows that SSS retrieval will be very sensitive to errors on auxiliary data. Specific efforts should be devoted to improving the quality of auxiliary data.

The role of intestinal microbiota of the marine fish (Acanthopagrus latus) in mercury biotransformation

2021 ◽  
Vol 277 ◽  
pp. 116768
Author(s):  
Tao-Tao Yang ◽  
Yong Liu ◽  
Sha Tan ◽  
Wen-Xiong Wang ◽  
Xun Wang
Keyword(s):  
Intestinal Microbiota ◽  
Marine Fish ◽  
Acanthopagrus Latus

The Role of the Everglades Mangrove Ecotone Region (EMER) in Regulating Nutrient Cycling and Wetland Productivity in South Florida

2011 ◽  
Vol 41 (sup1) ◽  
pp. 633-669 ◽  
Author(s):  
Victor H. Rivera-Monroy ◽  
Robert R. Twilley ◽  
Stephen E. Davis ◽  
Daniel L. Childers ◽  
Marc Simard ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
South Florida
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