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Responses of fish assemblage structure to large-scale weir construction in riverine ecosystems
Jo, Hyunbin,Jeppesen, Erik,Ventura, Marc,Buchaca, Teresa,Gim, Jeong-Soo,Yoon, Ju-Duk,Kim, Dong-Hwan,Joo, Gea-Jae Elsevier 2019 The Science of the total environment Vol.657 No.-
<P><B>Abstract</B></P> <P>Worldwide, increasing amounts of dams and weirs have been established in rivers in recent decades, often with drastic effects on their ecosystems. Between late 2009 and 2011, 16 large-scale dams were built in the main channels of the four largest rivers in South Korea, eight of these along the main channel of Nakdong River (300 km, 520 km in total). We studied the effect of these constructions on the fish community in the riparian zone based on intensive fish field surveys conducted in the littoral zone during 2007–2017, analysis of fishermen's catch data and molecular analysis of the diet of the keystone species, largemouth bass (<I>Micropterus salmoides</I>). Our results, based on RDA and GLM analyses, showed that environmental characteristics and fish species composition changed significantly with dam construction. Total fish abundance and biomass decreased after the start of the weir construction and fish richness decreased with time. The abundance and biomass of exotic fish decreased during construction but recovered afterwards, leading to higher proportions of exotics. Dominance and Shannon indices did not change significantly from before to after construction, while the Evenness index showed a significant decreasing trend. A comparison of the diet composition of largemouth bass showed decreasing genetic variation after construction. The changes in Functional Feeding Group (FFG) of the benthic communities at the study sites did not coincide with FFG changes in the prey items of largemouth bass, indicating a transition in feeding mode from before to after construction. In conclusion, the endemic and native fish species were most sensitive and showed lower resilience to disturbance by the large-scale dam construction than the translocated and exotic species, and the lake-like ecosystems after construction markedly improved the competitive capacity of these exotic fish over the native and endemic species in the riparian zone of the river.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Native fish species were more sensitive to disturbance and showed low resilience. </LI> <LI> Shift in the feeding mode of largemouth bass from before to after weir construction </LI> <LI> Exotic fish had improved competitive capacity after weir construction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bill, Nathan L.,Lim, Jong Min,Davis, Christina M.,Bä,hring, Steffen,Jeppesen, Jan O.,Kim, Dongho,Sessler, Jonathan L. The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.51
<P>A π-extended tetrathiafulvalene-boradiazaindacene chimera, ex-TTF-BODIPY, has been prepared. The resulting system undergoes sequential one-electron oxidations, allowing access to both the mono-oxidized radical cationic and dicationic states. Additionally, ex-TTF-BODIPY displays electrochromic and electrofluorochromic behaviour in the near-IR portion of the electromagnetic spectrum and functions as a redox switched “on–off–on” emissive system.</P> <P>Graphic Abstract</P><P>Ex-TTF-BODIPY functions as a near-IR electrochromic and electrofluorochromic switch, displaying redox controlled “on–off–on” emission features. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc02567a'> </P>
Bill, Nathan L.,Ishida, Masatoshi,Bä,hring, Steffen,Lim, Jong Min,Lee, Sangsu,Davis, Christina M.,Lynch, Vincent M.,Nielsen, Kent A.,Jeppesen, Jan O.,Ohkubo, Kei,Fukuzumi, Shunichi,Kim, Dongho,S American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.29
<P>A new class of redox-active free base and metalloporphyrins fused with the 1,3-dithiol-2-ylidene subunits present in tetrathiafulvalene, termed MTTFP (M = H<SUB>2</SUB>, Cu, Ni, Zn), have been prepared and characterized. The strong electron-donating properties of MTTFP were probed by electrochemical measurement and demonstrated that oxidation potentials can be tuned by metalation of the free base form, H<SUB>2</SUB>TTFP. X-ray crystal structures of H<SUB>2</SUB>TTFP, ZnTTFP, and CuTTFP revealed that a severe saddle-shape distortion was observed with the dithiole rings bent out of the plane toward one another in the neutral form. In contrast, the structure of the two-electron oxidized species (CuTFFP<SUP>2+</SUP>) is planar, corresponding to a change from a nonaromatic to aromatic structure upon oxidation. A relatively large two-photon absorption (TPA) cross-section value of H<SUB>2</SUB>TTFP<SUP>2+</SUP> (1200 GM) was obtained for the free base compound, a value that is much higher than those typically seen for porphyrins (<100 GM). Augmented TPA values for the metal complexes were also seen. The strong electron-donating ability of ZnTTFP was further enhanced by binding of Cl<SUP>–</SUP> and Br<SUP>–</SUP> as revealed by thermal electron-transfer between ZnTTFP and Li<SUP>+</SUP>-encapsulated C<SUB>60</SUB> (Li<SUP>+</SUP>@C<SUB>60</SUB>) in benzonitrile, which was “switched on” by the addition of either Cl<SUP>–</SUP> or Br<SUP>–</SUP> (as the tetrabutylammonium salts). The X-ray crystal structure of Cl<SUP>–</SUP>-bound ZnTTFP was determined and provided support for the strong binding between the Cl<SUP>–</SUP> anion and the Zn<SUP>2+</SUP> cation present in ZnTTFP.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-29/ja404830y/production/images/medium/ja-2013-04830y_0015.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja404830y'>ACS Electronic Supporting Info</A></P>