scholarly journals TROPHODYNAMICS OF MARINE ORGANISMS IN THE EPIPELAGIC LAYER OF THE OKHOTSK SEA IN 2000S

2019 ◽  
Vol 198 ◽  
pp. 143-163
Author(s):  
K. M. Gorbatenko ◽  
I. V. Melnikov
Keyword(s):  
Trophic Level ◽  
Isotope Composition ◽  
Marine Organisms ◽  
Organic Carbon Content ◽  
Total Production ◽  
Okhotsk Sea ◽  
Consumption Rates ◽  
Third Trophic Level ◽  
Zooplankton Production ◽  
Epipelagic Layer

New data on matter and energy transfer between major components of the Okhotsk Sea ecosystem are obtained on the base of trophodynamic modeling, taking into consideration their production and food consumption rates. The main trophodynamic relationships in the pelagic and bottom communities are determined from observations on zooplankton and nekton abundance, organic carbon content, food habits of marine organisms, and their isotope composition in 2000–2014. The total zooplankton production in the entire Okhotsk Sea in these years is assessed as 2616 . 106 t in raw weight, including 2275 . 106 t for non-predatory plankton, and 341 . 106 t for predatory plankton. So high total production of zooplankton is conditioned by favorable environmental conditions and dominance of high-productive species. Taking into account the rate of zooplankton consumption by predators, only 22.4 % of the total annual zooplankton production was consumed annually, with 16.2 % grazed by predatory plankton and 6.2 % by nekton. In carbon units, 831.0 . 106 tC was produced annually in the Okhotsk Sea at the first trophic level, 177.4 . 106 tC at the second trophic level, 18.1 . 106 tC at the third trophic level, 0.74 . 106 tC at the fourth trophic level, and 0.016 . 106 tC at the fifth trophic level. Pelagic nekton consumed 159 . 106 tC annually. The nekton prey included 85.5 % of zooplankton, 12.8 % of nekton, and 1.7 % of zoobenthos, by biomass. The main part of zooplankton consumed by nekton (50.7 %) was grazed by walleye pollock, 18.9 % by herring, 16.6 % by squids, 7.6 % by capelin, 5.3 % by deep-sea smelt, and 0.9 % by salmons. The total annual production of organisms in the epipelagic layer of the Okhotsk Sea exceeded 109 tons of C (1027.4 . 106 tC/year equal to the biomass of 17.85 . 109 t in wet weight). Primary production is estimated as 67.60 % of gross production in carbon units, microheterotrophic organisms produce 13.30 %, dominant zooplankton groups — 18.60 % (copepods 11.40 %, euphausiids 5.50 %, sagittas 1.20 %, and hyperiids 0.50 %), the portion of nekton production is estimated as 0.13 % of gross production.

scholarly journals The Ice-Rich Permafrost Sequences as a Paleoenvironmental Archive for the Kara Sea Region (Western Arctic)

2021 ◽  
Vol 9 ◽  
Author(s):  
I. D. Streletskaya ◽  
A. A. Pismeniuk ◽  
A. A. Vasiliev ◽  
E. A. Gusev ◽  
G. E. Oblogov ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Marine Sediments ◽  
Isotope Composition ◽  
Kara Sea ◽  
Coastal Sediments ◽  
Organic Carbon Content ◽  
Ground Ice ◽  
Geochemical Composition ◽  
The Holocene ◽  
Mis 3

The Kara Sea coast and part of the shelf are characterized by wide presence of the ice-rich permafrost sequences containing massive tabular ground ice (MTGI) and ice wedges (IW). The investigations of distribution, morphology and isotopic composition of MTGI and IW allows paleoenvironmental reconstructions for Late Pleistocene and Holocene period in the Kara Sea Region. This work summarizes result of long-term research of ice-rich permafrost at eight key sites located in the Yamal, Gydan, Taimyr Peninsulas, and Sibiryakov Island. We identified several types of ground ice in the coastal sediments and summarized data on their isotopic and geochemical composition, and methane content. We summarized the available data on particle size distribution, ice chemical composition, including organic carbon content, and age of the enclosing ice sediments. The results show that Quaternary sediments of the region accumulated during MIS 5 – MIS 1 and generally consisted of two main stratigraphic parts. Ice-rich polygenetic continental sediments with syngenetic and epigenetic IW represent the upper part of geological sections (10–15 m). The IW formed in two stages: in the Late Pleistocene (MIS 3 – MIS 2) and in the Holocene cold periods. Oxygen isotope composition of IW formed during MIS 3 – MIS 2 is on average 6‰ lower than that of the Holocene IW. The saline clay with rare sand layers of the lower part of geological sections, formed in marine and shallow shelf anaerobic conditions. MTGI present in the lower part of the sections. The MTGI formed under epigenetic freezing of marine sediments immediately after sea regression and syngenetic freezing of marine sediments in the tidal zone and in the conditions of shallow sea.

Parasitic infection alters the physiological response of a marine gastropod to ocean acidification

Parasitology ◽  
2016 ◽  
Vol 143 (11) ◽  
pp. 1397-1408 ◽  
Author(s):  
C. D. MACLEOD ◽  
R. POULIN
Keyword(s):  
Oxygen Consumption ◽  
Ocean Acidification ◽  
Parasitic Infection ◽  
Marine Organisms ◽  
Ion Concentration ◽  
Metabolic Effects ◽  
Control Group ◽  
Glucose Content ◽  
Hydrogen Ion Concentration ◽  
Consumption Rates

SUMMARYIncreased hydrogen ion concentration and decreased carbonate ion concentration in seawater are the most physiologically relevant consequences of ocean acidification (OA). Changes to either chemical species may increase the metabolic cost of physiological processes in marine organisms, and reduce the energy available for growth, reproduction and survival. Parasitic infection also increases the energetic demands experienced by marine organisms, and may reduce host tolerance to stressors associated with OA. This study assessed the combined metabolic effects of parasitic infection and OA on an intertidal gastropod,Zeacumantus subcarinatus. Oxygen consumption rates and tissue glucose content were recorded in snails infected with one of three trematode parasites, and an uninfected control group, maintained in acidified (7·6 and 7·4 pH) or unmodified (8·1 pH) seawater. Exposure to acidified seawater significantly altered the oxygen consumption rates and tissue glucose content of infected and uninfected snails, and there were clear differences in the magnitude of these changes between snails infected with different species of trematode. These results indicate that the combined effects of OA and parasitic infection significantly alter the energy requirements ofZ. subcarinatus, and that the species of the infecting parasite may play an important role in determining the tolerance of marine gastropods to OA.

Understanding Effects of OAE 2 in the Marginal-marine Environment: A Multi-proxy approach from Bagh Beds, Western India

2020 ◽  
Author(s):  
Bikash Ranjan Sahu ◽  
Sohom Roy ◽  
Prasanta Sanyal
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Marine Environment ◽  
Nutrient Dynamics ◽  
Isotope Composition ◽  
Western India ◽  
Organic Carbon Content ◽  
Terrestrial Environment ◽  
Shallow Marine ◽  
Carbon Reservoir

<p>The Cenomanian-Turonian (C/T) Oceanic Anoxic Event 2 (OAE 2) at ~94 million years ago was characterized by severe depletion in marine water oxygen levels and extreme perturbations in the carbon cycle at a global scale that lasted for 5 to 6-million years. However, wealth of the data comes mainly from deep marine records, hugely limiting our understanding on the contemporaneous terrestrial environmental conditions. Here, we present major and trace element concentrations, carbon isotope composition of carbonates (δ<sup>13</sup>C<sub>carb</sub>) and organic matter (δ<sup>13</sup>C<sub>bulk</sub>), organic carbon content (TOC), and biomarker composition from a ~20 m thick well-preserved shallow marine sequence from the Bagh Beds in Uchad, western India in order to investigate the nutrient dynamics, productivity variations and carbon reservoir perturbations in shallow marine as well as in terrestrial environment. Based on litho-stratigraphy, the Uchad section is divided into Lower Cenomanian, Turonian and Upper Coniacian units. A total of ~5‰ increase in the δ<sup>13</sup>C<sub>carb</sub> and 0.07% in TOC values and a sharp 1.7‰ decrease in the δ<sup>13</sup>C<sub>bulk </sub>values in Lower Cenomanian suggest large changes in organic carbon recycling before the advent of OAE 2. Higher terrigenous influx and micro-nutrient supply in the lower parts is also suggested from relatively higher concentrations of Al, Ti, Th, Fe, Zn, Ni and K, although their concentrations decrease rapidly above the C/T boundary. Significant correlation observed between δ<sup>13</sup>C<sub>bulk</sub> and δ<sup>13</sup>C<sub>carb</sub> (r=0.51, p=0.03) supports an authigenic organic matter production in the shallow marine environment. However, minor enrichments in redox-sensitive elements like Mo, V and U observed above the C/T boundary probably suggest that the shallow marine region was relatively less affected during the initial anoxic phases. Lack of correlation between redox-sensitive elements and Al or Ti concentrations (r <0.12) suggest that there is minimal influence of detrital supply on recycling of U, V and Mo. Interestingly, Lower Turonian units show large positive excursions in redox-sensitive elements as well as increases in U/Th, Ni/Co and V/(V+Ni) values, which are succeeded by a major decrease in δ<sup>13</sup>C<sub>carb </sub>values (7.6‰) and increase in the TOC values by 0.15%, thereby suggesting occurrence of a more expanded episode of anoxia in Lower Turonian that perturbed the shallow marine carbon reservoir. Ba/Al ratios are variable throughout the section, although large positive spikes preceding and succeeding the anoxic phases suggest a causal link between organic matter productivity and anoxia.</p>

scholarly journals Co-infections and the third trophic level

2012 ◽  
Vol 26 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Noah K. Whiteman
Keyword(s):  
Trophic Level ◽  
The Third ◽  
Third Trophic Level

Trophic Levels

Ecology ◽  
2012 ◽  
Author(s):  
Lee A. Dyer
Keyword(s):  
Trophic Level ◽  
Evolutionary Biology ◽  
Trophic Levels ◽  
Trophic Chain ◽  
The Third ◽  
Third Trophic Level ◽  
Primary Consumers ◽  
Trophic Chains ◽  
Secondary Consumers ◽  
Applied Fields

Trophic levels are determined by feeding relationships, with basal levels consisting of primary producers or detritus and upper levels based on consumption of these basal levels. Organisms on the second trophic level are referred to as primary consumers, which are in turn consumed by secondary consumers, and so on up a theoretical trophic chain. Primary consumers consist of herbivores and detritivores, while the third trophic level and those above include predators and parasites. Energy and matter move up trophic chains, and some compounds, including various toxins, may bioaccumulate at upper trophic levels. The concept of trophic level has generated a sizeable literature yielding useful ecological models, such as trophic cascades, and debates about top-down versus bottom-up regulation of herbivores. This article focuses on the contributions of the trophic-level concept to ecological theory, evolutionary biology, and the applied fields of agricultural and global change biology.

scholarly journals Herbivore range expansion triggers adaptation in a subsequently-associated third trophic level species and shared microbial symbionts

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Fushi Ke ◽  
Shijun You ◽  
Sumei Huang ◽  
Weijun Chen ◽  
Tiansheng Liu ◽  
...  
Keyword(s):  
Trophic Level ◽  
Range Expansion ◽  
Third Trophic Level ◽  
Microbial Symbionts
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