Dinitrogen fixation, the biological reduction in N gas to ammonia contributes to the supply of new nitrogen in the surface ocean. To understand the diversity and abundance of potentially diazotrophic (N fixing) microorganisms associated with marine zooplankton, especially copepods, the nifH gene was studied using zooplankton samples collected in the Pacific Ocean. In total, 257 nifH sequences were recovered from 23 nifH-positive DNA extracts out of 90 copepod samples. The nifH genes derived from cyanobacteria related to Trichodesmium, α- and γ-subdivisions of proteobacteria, and anaerobic euryarchaeota related to Methanosaeta concilii were detected. Our results indicated that Pleuromamma, Pontella, and Euchaeta were the major copepod genera hosting dinitrogen fixers, though we found no species-specific association between copepods and dinitrogen fixers. Also, the digital PCR provided novel data on the number of copies of the nifH gene in individual copepods, which we report the range from 30 to 1666 copies per copepod. This study is the first systematic study of zooplankton-associated diazotrophs, covering a large area of the open ocean, which provide a clue to further study of a possible new hotspot of N fixation.
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http://dx.doi.org/10.1002/mbo3.385 | DOI Listing |
Life (Basel)
December 2024
Imaging and Analysis Center, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, 6965 Cumberland Gap Pkwy, Harrogate, TN 37752, USA.
Zooplanktonic copepods represent a major biological mass in the marine food chain that can be affected by climate change. Monitoring the health of this critical biomass is essential for increasing our understanding of the impact of environmental changes on marine environments. Since the lipidomes of marine organisms are known to adapt to alterations in pH, temperature, and availability of metabolic precursors, lipidomics is one technology that can be used for monitoring copepod adaptations.
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January 2025
State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, Shandong, China.
The Japanese anchovy (Engraulis japonicus), a finfish with the largest biomass of a single species in the Yellow and East China Seas, plays an important pivotal role in converting zooplanktons into high trophic fish in the food web. As a result, the fish is regard as a key species in its habiting ecosystem. However, the lack of genomic resources hampers our understanding of its genetic diversity and differentiation, as well as the evolutionary dynamics.
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January 2025
Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada. Electronic address:
Mercury (Hg) and persistent organic pollutant (POP) accumulation among species and biomagnification through food webs is typically assessed using stable isotopes of nitrogen (δN) and carbon (δC) in bulk (whole) tissues. Yet, bulk isotopic approaches have limitations, notably from the potential overlap of isotope values from different dietary sources and from spatial variation in source (baseline) signals. Here, we explore the potential of fatty acid carbon isotopes (FA δC) to (1) evaluate the trophic structure of a marine food web, (2) distinguish feeding patterns among four marine mammal consumers, (3) trace contaminant biomagnification through a food web, and (4) explain interspecific variation in contaminants among high-trophic position predators.
View Article and Find Full Text PDFFoods
December 2024
Department of Agricultural and Food Sciences (DISTAL), University of Bologna, 47521 Cesena, Italy.
Zooplankton such as copepods and krill are currently used to produce marine oil supplements, with the aim of helping consumers achieve the recommended intake of n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs). Oils from lower trophic levels differ from fish oil in the distribution of lipids into different classes, and this can influence the bioaccessibility of fatty acids, i.e.
View Article and Find Full Text PDFBiology (Basel)
November 2024
Biology Department, University of New Mexico, Albuquerque, NM 87131-0001, USA.
Maps of (baseline) δC and δN values of primary producers or consumers near the base of food webs provide crucial information for interpreting patterns in the isotopic composition of consumers that occupy higher trophic levels. In marine systems, understanding how oceanographic variables influence these values enables the creation of dynamic isoscapes across time and space, providing insights into how ecosystems function. The San Jorge Gulf (SJG) in the southwest Atlantic Ocean (45° S-47° S) is an area of particular importance, as it is located on one of the most productive continental shelves in the world, supporting large fisheries and marine mammal and seabird populations.
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