A Scientometric Study of the Limnological Societies
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395 Article A scientometric study of the limnological societies: inferences of research collaboration and core topics based on publication networks Ji Yoon Kim,1 Gea-Jae Joo,1 Hyun-Woo Kim,2 Gu-Yeon Kim,1 and Yuno Do1*† 1 Department of Biological Sciences, Pusan National University, Busan, Korea 2 Department of Environmental Education, Sunchon National University, Suncheon, Korea * Corresponding author: [email protected] † Current address: Pusan National University Received 23 March 2015; accepted 30 October 2015; published 14 July 2016 Abstract Scientometric analysis of limnological societies and related publications revealed complex relationships among research topics and research collaborations. We applied scientometric analysis, word networks, bibliographic coupling, and author networks analysis, to 34777 publications related to limnology and monsoon research. We analyzed usage frequencies of limnology-related words in a Google corpus and found that usage frequencies of most limnological terms peaked during the 1980s. Social interest in the term “limnology” showed a gradually decreasing trend after the late 1990s. Monsoon research was focused in the Asian–Indian region but not in the European, African, and American regions. Word networks of limnological studies related to monsoons were mainly grouped into 3 clusters (Indian monsoons, East Asian monsoons, and monsoon assessment clusters). In the citation network of limnology journals, water quality, plankton, and invertebrate research groups generally showed strong internal citation networks. An author connection map of the limnological societies revealed strong modulators in the international societies, whereas research collaboration was rather limited to small groups within the entire network. This retrospective analysis will provide meaningful information to further develop and enhance international collaboration within limnological studies. Key words: centrality, citation network, limnology, monsoon, ngram, text mining Introduction Today, the number of publications is skyrocketing, and research themes are more complicated as increasing col- Limnology covers broad types of inland waters; it addresses laborations develop among different scientific fields (e.g., emerging environmental issues and has developed briskly biology and information technology, molecular biology, over the last 100 years. Diverse academic societies related and field ecology). This rapid progression of scientific to limnology have focused on and contributed to interaction publications may further constrain the single expert among biological, hydrological, and geological components review with a wide mandate. Meanwhile, as many and ecological issues (Wetzel 2000). Timely reviews of scientific societies have accumulated stacks of research these limnological achievements have organized scattered papers and historical documents, we may consider other findings and provided summary information to the societies types of reviewing methods that can provide a quantitative and researchers. Based on these benefits, extensive reviews evaluation by using collected publications. have focused on specific limnological topics (Wetzel 2000, Scientometrics is concerned with the quantitative Jeppesen et al. 2010, Moss et al. 2013) because expert features and characteristics of science and scientific reviews generally require and largely rely on researchers research. Scientometrics also focuses on the analysis of who have broad knowledge and continued experience in an publications to review core topics and the relationships academic field. among author networks. Applications of this type of quan- DOI: 10.5268/IW-6.3.849 Inland Waters (2016) 6, pp.395-405 © International Society of Limnology 2016 396 Kim et al. Table 1. List of limnological journals used in the scientometric analysis. Journal title # of publications used Time period Internal citation links Annales de Limnologie - International Journal of Limnology 739 1990–2015 380 Aquatic Ecology 613 2003–2015 207 Aquatic Sciences 920 1989–2015 588 Freshwater Biology 4777 1973–2015 15 948 Freshwater Science 1734 1988–2015 6548 Hydrobiologia 15 984 1971–2015 31 718 Inland Waters 134 2011–2015 54 Journal of Limnology 457 2007–2015 270 Limnologica 548 2002–2015 340 Limnology 353 2003–2015 137 Limnology and Oceanography 6730 1970–2015 23 421 titative measurement have benefited reviews of the (river continuum, flood pulse, serial discontinuity, and historical development of research topics and confined nutrient spiraling), and types of monsoon (Asian, East how research collaborations were forged within diverse Asian, Indian, African, Australian, and North American). scientific fields. Several studies analyze bibliographies in Usage frequency of the term was computed by dividing social studies (Hood and Wilson 2001), yet scientometric the number of instances of the ngram in a given year by reviews of limnology remain limited (Liao and Huang the total number of words in the corpus in that year 2013, Alves et al. 2014, Gao et al. 2014). (Michel et al. 2011). Accordingly, we examined scientific publications to We also considered 32 989 scientific papers, published discover trends in limnological research and researcher in the Annales de Limnologie - International Journal of networks. We analyzed the development of research Limnology (739 articles), Aquatic Ecology (613), Aquatic topics, keywords, and author networks in limnological Sciences (920), Freshwater Biology (4777), Freshwater societies by using published papers in international Science (1734), Hydrobiologia (15 984), Inland Waters limnology journals. We also analyzed relative interest in (134), Journal of Limnology (457), Limnologica (548), limnological terms using the Google Ngram. This study Limnology (353), and Limnology and Oceanography addressed the following research questions in limnologi- (6730). This corpus was used for the topic analysis, author cal societies: (1) What were the most issuing topics? (2) connection map analysis, and citation network analysis Which study groups were closely related? (3) How have (Table 1). Only English language papers were included. researchers cooperated on diverse topics? We expected Scientific papers in the international journals were to find a distinct composition of research topics and collected manually by searching in the journal publication insightful implications into core research networks. database and Web of Science academic databases. Monsoon-related studies constituted one of the Methods important issues in the limnological studies. For a broad interpretation of limnological studies related to Text corpora monsoons, we collected scientific publications in the in- ternational journals by using academic web searches. We analyzed relative interest in limnological terms and We searched “monsoon” and “limnology” in Google related issues by using the Google Ngram database, which Scholar (Harzing 2013) and Web of Science academic includes 5 million books published from the 1800s to the databases and collected 28 330 papers. Initial search 2000s (Michel et al. 2011, Roth 2014). Previous studies results still contained many oceanographic studies; thus, based on the ngram database found meaningful trends in we excluded those results by using specific search public interest and social issues ranging across diverse operators (i.e., -oceanography, -ocean, -sea). Finally, issues (Acerbi et al. 2013). We compared public interest 1788 papers were selected for the topic analysis of on ecological issues (climate change, water quality, land monsoon research. use, acid rain, biomanipulation), limnological concepts © International Society of Limnology 2016 DOI: 10.5268/IW-6.3.849 Core topics and research networks in the limnological societies 397 Scientometric analysis 1.6.1 (Leiden University, Netherland) and Gephi 0.8.2 (The Gephi Consortium, France) with binary counting methods We merged the titles, authors, abstracts, and keyword to visualize the network and density map of the collected information of each article into a single text corpus and terms (Waltman et al. 2010). Synonyms were merged into a prepared the text dataset for the various text-mining single term before the analysis. Research networks can also techniques. To find the major terms and issues in the pub- be inferred from citation patterns in the scientific literature. lications, we used word frequency counts, word network We analyzed citation networks in the international analysis, citation networks, and author network analyses. limnology journals with CitNetExplorer 1.0.0 (Leiden The word frequency count analyzed unigrams and bigrams University, Netherland; van Eck and Waltman 2014). Non- to discover the research terms in the dataset. Meaningless matching cited references were not included in the network combinations of prepositions (e.g., “of the,” “for a”) were because we focused more on the internal network in the excluded in the word frequency count. limnological societies than on the entire relationship with A term map based on collected text corpora was created other disciplines. For a quantitative understanding of the for network visualization. A term map (or word network) network components (i.e., terms, organizations, authors), locates terms so that the distance between 2 terms provides eigenvector centralities were calculated to characterize the an indication of the number of co-occurrences of the terms. global prominence of a vertex in the network (Bonacich Closely located terms with smaller distances