scholarly journals Diversity, Community Composition and Abundance of Anammox Bacteria in Sediments of the North Marginal Seas of China

2016 ◽  
Vol 31 (2) ◽  
pp. 111-120 ◽  
Author(s):  
Ahmed Shehzad ◽  
Jiwen Liu ◽  
Min Yu ◽  
Shakeela Qismat ◽  
Jingli Liu ◽  
...  
2009 ◽  
Vol 6 (2) ◽  
pp. 267-274 ◽  
Author(s):  
H. Thomas ◽  
L.-S. Schiettecatte ◽  
K. Suykens ◽  
Y. J. M. Koné ◽  
E. H. Shadwick ◽  
...  

Abstract. The coastal ocean is a crucial link between land, the open ocean and the atmosphere. The shallowness of the water column permits close interactions between the sedimentary, aquatic and atmospheric compartments, which otherwise are decoupled at long time scales (≅ 1000 yr) in the open oceans. Despite the prominent role of the coastal oceans in absorbing atmospheric CO2 and transferring it into the deep oceans via the continental shelf pump, the underlying mechanisms remain only partly understood. Evaluating observations from the North Sea, a NW European shelf sea, we provide evidence that anaerobic degradation of organic matter, fuelled from land and ocean, generates total alkalinity (AT) and increases the CO2 buffer capacity of seawater. At both the basin wide and annual scales anaerobic AT generation in the North Sea's tidal mud flat area irreversibly facilitates 7–10%, or taking into consideration benthic denitrification in the North Sea, 20–25% of the North Sea's overall CO2 uptake. At the global scale, anaerobic AT generation could be accountable for as much as 60% of the uptake of CO2 in shelf and marginal seas, making this process, the anaerobic pump, a key player in the biological carbon pump. Under future high CO2 conditions oceanic CO2 storage via the anaerobic pump may even gain further relevance because of stimulated ocean productivity.


2016 ◽  
Vol 50 (5) ◽  
pp. 387-394
Author(s):  
S. A. Kudrenko

Abstract The data about the community composition, number and biomass of amphipods in three gulfs of the North-Western Black Sea are presented. The amphipod communities of the gulfs of Yahorlyk, Karkinit, and Tendra were studied and the species composition was compared with the previously published data. For each particular gulf, the list of amphipod species was composed. The quantitative parameters of the amphipod communities in the studied localities in different years were described.


1996 ◽  
Vol 46 (3) ◽  
pp. 230-250 ◽  
Author(s):  
Sergei A. Gorbarenko

Stable isotopes, geochemical, lithological, and micropaleontological results from cores from the far northwest (FNW) Pacific and the Okhotsk and Bering seas are used to reconstruct the regional environment for the last glaciation, the deglacial transition, and the Holocene. δ18O records of planktonic foraminifera of the region show two “light” shifts during deglacial time, provoked by the freshening of the surface water and climate warming. These north Pacific terminal events (T1ANP and T1BNP) with ages of 12,500 and 9300 yr B.P., respectively, occur almost simultaneously with two episodes of accelerated glacier melting around the North Atlantic. Along with the isotopic shifts, the CaCO3 content in regional sediments increased abruptly (1A and 1B carbonate peaks), probably due to changes of productivity and pore water chemistry of surface sediments. Organic matter and opal concentration increased during the transition (between T1ANP and T1BNP events) in the sediments of the FNW Pacific and the southern part of the Bering Sea and opal content increased in the Holocene in the Bering and Okhotsk Seas. δ13C records of cores from the Okhotsk and Bering seas and the FNW Pacific do not contradict the hypothesis of increased intermediate water formation in the region during glaciation. During deglaciation, accumulation of the coarse terrigenous component decreased in sediments of the Bering Sea and the FNW Pacific before the T1ANP event, probably as a result of rising sea level and opening of the Bering Strait.


2014 ◽  
Vol 70 (1) ◽  
pp. 105-117 ◽  
Author(s):  
Jiwen Liu ◽  
Xiaoshou Liu ◽  
Min Wang ◽  
Yanlu Qiao ◽  
Yanfen Zheng ◽  
...  

2003 ◽  
Vol 11 (2) ◽  
pp. 103-139 ◽  
Author(s):  
Robie W Macdonald ◽  
Brian Morton ◽  
Sophia C Johannessen

Chemical contaminants in the North Pacific Ocean include hydrocarbons, persistent organic pollutants, metals, persistent solids, and domestic pollutants. Here, we review contaminant research conducted over the past decade, finding that the effects of contaminants cannot be considered in isolation from other major factors causing change to North Pacific ecosystems. Climate change, over-fishing, habitat destruction, eutrophication, and the introduction of exotic species interact with one another and alter contaminant pathways. Climate change and over-fishing are perceived as the main threats to the remote northern marginal seas, the central North Pacific, and the west coast of North America, with contaminants engendering local concern, especially in semi-enclosed bodies of water. Climate change receives less attention in Asian waters, probably because widespread habitat destruction and contamination provide, by themselves, an impending ecological disaster. A systematic approach is urgently required to recognize and prioritize the threats to North Pacific coastal ecosystems. This should include box models, case studies, proxy records, and time series. The ocean should be monitored as a system, including physical media (water, sediment) and the full trophic range of the food web, and tissues should be preserved in archives to provide a resource for understanding emerging concerns. Finally, the development of ecological indicators is urgently required to provide a robust warning system based on the health of the marine ecosystems themselves. It is time to conduct a multi-national assessment of the North Pacific Ocean to develop a common, factual awareness of the threats looming over our coastal waters. Key words: contaminants, climate change, ecosystem change, monitoring, North Pacific, trends.


2020 ◽  
Vol 655 ◽  
pp. 43-57
Author(s):  
S Allen ◽  
S Henson ◽  
A Hickman ◽  
C Beaulieu ◽  
PC Doncaster ◽  
...  

As primary producers, phytoplankton play a pivotal role in the marine environment and are central to many biogeochemical processes. Changes to phytoplankton community composition could have major consequences for wider ecosystem functioning and may occur in response to climate change. Here we describe multi-decadal variability in phytoplankton community structure using taxonomic data from the Continuous Plankton Recorder collected in the North-East Atlantic from 1969-2013, using a total of 42 diatom and dinoflagellate taxa. We considered a range of characteristics of community structure, including taxonomic diversity and community stability and disorder, and how these characteristics change in response to sea surface temperature, mixed layer depth and the North Atlantic Oscillation. We found that phytoplankton community composition was largely stable on interannual timescales. A change in community composition occurred between 1985 and 1995 due to an increased dominance of 2 diatom taxa (Rhizosolenia styliformis and Thalassiosira spp.); however, after this period, the community returned to its previous composition. Further, a community disorder analysis found that phytoplankton compositional structure became more rigid in recent years, which may lead to an eventual community shift in the future. In contrast to previous studies that revealed relationships between total phytoplankton abundance or biomass and environmental forcing, we found that community structure had, at most, a very weak relationship with the environmental parameters tested. Changes to the physical environment may therefore have less influence at interannual timescales on phytoplankton community structure than previously thought.


2015 ◽  
Vol 12 (14) ◽  
pp. 11061-11087
Author(s):  
T. Shiozaki ◽  
S. Takeda ◽  
S. Itoh ◽  
T. Kodama ◽  
X. Liu ◽  
...  

Abstract. Nitrogen fixation in the Kuroshio influences nitrogen balance in the North Pacific Ocean. The genus Trichodesmium is recognized as a major diazotroph in the Kuroshio. Although its abundance is higher in the Kuroshio than in adjacent waters, the reason for this difference remains unclear. The present study investigated the abundance of Trichodesmium spp. and nitrogen fixation together with concentrations of dissolved iron and phosphate, whose availabilities potentially control diazotrophy, in the Kuroshio and its marginal seas. We performed the observations near the Miyako Islands, which form part of the Ryukyu Islands, situated along the Kuroshio, since satellite analysis suggested that material transport could occur from the islands to the Kuroshio. Trichodesmium spp. bloomed (> 20 000 filaments L−1) near the Miyako Islands, and the abundance was high in the Kuroshio and the Kuroshio bifurcation region of the East China Sea, but was low in the Philippine Sea. The abundance of Trichodesmium spp. was significantly correlated with the total nitrogen fixation activity. The surface concentrations of dissolved iron (0.19–0.89 nM) and phosphate (< 3–36 nM) were similar for all of the study areas, indicating that the nutrient distribution could not explain the spatial differences in Trichodesmium spp. abundance and nitrogen fixation. We used a numerical model to simulate the transportation of water around the Ryukyu Islands to the Kuroshio. Our results indicate that Trichodesmium growing around the islands situated along the Kuroshio is potentially important for determining diazotrophy in this region.


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