Potential invasions of phytoplankton in ship ballast water at South Korean ports

2016 ◽  
Vol 67 (12) ◽  
pp. 1906 ◽  
Author(s):  
Bonggil Hyun ◽  
Kyoungsoon Shin ◽  
Min-Chul Jang ◽  
Pung-Guk Jang ◽  
Woo-Jin Lee ◽  
...  

We studied the phytoplankton communities in ballast water in ships that arrived at two South Korean ports. We determined the potential for phytoplankton in the ballast water to invade the South Korean marine environment, given the specific growth rates of the phytoplankton, the delay before the phytoplankton started growing, and the rate at which the phytoplankton would initially disperse in ports and bays. Most of the phytoplankton in the ballast water samples originated in countries such as China and Japan that are adjacent to South Korea, and diatoms dominated these phytoplankton communities. The abundance of phytoplankton in a sample did not appear to be related to any particular environmental parameter, including the voyage duration. However, the number of phytoplankton taxa in a sample decreased as the voyage duration increased. The survival and growth of phytoplankton communities in the South Korean marine environment were assessed, and we found that most invasions failed at the initial dispersal phase, especially when a community was introduced to pier-side seawater. However, some members of phytoplankton communities, if they were dispersed and where conditions were highly eutrophic, could grow fast enough to overcome the initial dispersal phase in South Korean ports and bays.

1998 ◽  
Vol 37 (4-5) ◽  
pp. 259-262 ◽  
Author(s):  
Bjarne R. Horntvedt ◽  
Morten Rambekk ◽  
Rune Bakke

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).


2021 ◽  
Author(s):  
Julia Duerschlag ◽  
Wiebke Mohr ◽  
Timothy G. Ferdelman ◽  
Julie LaRoche ◽  
Dhwani Desai ◽  
...  

AbstractOligotrophic ocean gyre ecosystems may be expanding due to rising global temperatures [1–5]. Models predicting carbon flow through these changing ecosystems require accurate descriptions of phytoplankton communities and their metabolic activities [6]. We therefore measured distributions and activities of cyanobacteria and small photosynthetic eukaryotes throughout the euphotic zone on a zonal transect through the South Pacific Ocean, focusing on the ultraoligotrophic waters of the South Pacific Gyre (SPG). Bulk rates of CO2 fixation were low (0.1 µmol C l−1 d−1) but pervasive throughout both the surface mixed-layer (upper 150 m), as well as the deep chlorophyll a maximum of the core SPG. Chloroplast 16S rRNA metabarcoding, and single-cell 13CO2 uptake experiments demonstrated niche differentiation among the small eukaryotes and picocyanobacteria. Prochlorococcus abundances, activity, and growth were more closely associated with the rims of the gyre. Small, fast-growing, photosynthetic eukaryotes, likely related to the Pelagophyceae, characterized the deep chlorophyll a maximum. In contrast, a slower growing population of photosynthetic eukaryotes, likely comprised of Dictyochophyceae and Chrysophyceae, dominated the mixed layer that contributed 65–88% of the areal CO2 fixation within the core SPG. Small photosynthetic eukaryotes may thus play an underappreciated role in CO2 fixation in the surface mixed-layer waters of ultraoligotrophic ecosystems.


Author(s):  
Su Yeon Roh ◽  
Ik Young Chang

To date, the majority of research on migrant identity negotiation and adjustment has primarily focused on adults. However, identity- and adjustment-related issues linked with global migration are not only related to those who have recently arrived, but are also relevant for their subsequent descendants. Consequently, there is increasing recognition by that as a particular group, the “1.5 generation” who were born in their home country but came to new countries in early childhood and were educated there. This research, therefore, investigates 1.5 generation South Koreans’ adjustment and identity status in New Zealand. More specifically, this study explores two vital social spaces—family and school—which play a pivotal role in modulating 1.5 generation’s identity and adjustment in New Zealand. Drawing upon in-depth interviewing with twenty-five 1.5 generation Korean-New Zealanders, this paper reveals that there are two different experiences at home and school; (1) the family is argued to serve as a key space where the South Korean 1.5 generation confirms and retains their ethnic identity through experiences and embodiments of South Korean traditional values, but (2) school is almost the only space where the South Korean 1.5 generation in New Zealand can acquire the cultural tools of mainstream society through interaction with English speaking local peers and adults. Within this space, the South Korean 1.5 generation experiences the transformation of an ethnic sense of identity which is strongly constructed at home via the family. Overall, the paper discusses that 1.5 generation South Koreans experience a complex and contradictory process in negotiating their identity and adjusting into New Zealand through different involvement at home and school.


2001 ◽  
Vol 58 (2) ◽  
pp. 386-393 ◽  
Author(s):  
John A Sweka ◽  
Kyle J Hartman

Brook trout (Salvelinus fontinalis) were held in an artificial stream to observe the influence of turbidity on mean daily consumption and specific growth rates. Treatment turbidity levels ranged from clear (<3.0 nephelometric turbidity units (NTU)) to very turbid water (> 40 NTU). Observed mean daily specific consumption rates were standardized to the mean weight of all brook trout tested. Turbidity had no significant effect on mean daily consumption, but specific growth rates decreased significantly as turbidity increased. Brook trout in turbid water became more active and switched foraging strategies from drift feeding to active searching. This switch was energetically costly and resulted in lower specific growth rates in turbid water as compared with clear water. Bioenergetics simulations were run to compare observed growth with that predicted by the model. Observed growth values fell below those predicted by the model and the difference increased as turbidity increased. Abiotic factors, such as turbidity, which bring about changes in the activity rates of fish, can have implications for the accuracy of predicted growth by bioenergetics models.


2007 ◽  
Vol 39 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Shida Rastegari Henneberry ◽  
Seong-huyk Hwang

The first difference version of the restricted source-differentiated almost ideal demand system is used to estimate South Korean meat demand. The results of this study indicate that the United States has the most to gain from an increase in the size of the South Korean imported meat market in terms of its beef exports, while South Korea has the most to gain from this expansion in the pork market. Moreover, the results indicate that the United States has a competitive advantage to Australia in the South Korean beef market. Results of this study have implications for U.S. meat exports in this ever-changing policy environment.


Cancer ◽  
2021 ◽  
Vol 127 (10) ◽  
pp. 1638-1647
Author(s):  
Yuh‐Seog Jung ◽  
Jungirl Seok ◽  
Seri Hong ◽  
Chang Hwan Ryu ◽  
Junsun Ryu ◽  
...  

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