A picture worth forty-one words: Charles Elton, introduced species and the 1936 Admiralty map of British Empire shipping

摘要

In the twenty-first century every registered commercial ship and many private pleasure craft carry Global Positioning System transponders. Such satellite-facilitated communication enables constant contact with their home bases, but also allows online services such as MarineTraffic.com to generate global maps pinpointing nearly 40,000 vessels in something close to real time. In the interwar era such a feat required extensive post-facto data collection and manual drafting. B. R. 84 was published in July 1937, several months after its title date. Why go to the trouble of producing such a document at all? Mainly, perhaps, for its propaganda value. Sorting out all the intended messages and audiences in detail exceeds the scope of this paper. It can be said that British shipping and shipbuilding during the interwar period were complicated by treaty obligations, commercial competition and the ongoing obsolescence of external combustion (coal-fired steam) engines. Failing to keep up in any of these matters would have unwelcome consequences. Maritime historian Greg Kennedy summarised it succinctly: 'For Britain, her merchant marine represented a crucial strategic and economic lifeline over which military reserves and materials were transported to and from the far reaches of the empire. Just as important, this strategic resource transported the vital goods and material Britain required to maintain one of the world's strongest economies and to obtain the raw materials which fed a modern industrial society'. With the Merchant Marine Act of 1936, the United States was embarking on a program of reform and expansion that the British saw as a threat to their traditional (if fading) domination of oceangoing cartage. And as noted, by 1936 the seeds of World War Two had plainly sprouted in Asia and were germinating in Europe. Military and commercial shipping and shipbuilding were intimately linked by subsidies and policies that effectively allowed rapid nationalisation of private fleets for transporting troops and materiel. Perhaps it wasn't coincidental that the title date chosen for B. R. 84, 7 March 1936, was the day Germany abrogated the treaties of Versailles and Locarno by remilitarising the Rhineland. Similarly, B. R. 135 commemorated the date a Brussels conference of the 1922 'Nine Power Treaty' nations, aimed at ending the Sino-Japanese War, adjourned without achieving its purpose. B. R. 84 was invested with explicit and tacit meanings that enrich our understanding of transportation history. Charles Elton found additional meaning as incidental to the map's original purposes as redistribution of marine biota was to the activity it depicted. Elton, a pioneer of animal ecology and science-based nature conservation, could have made much better use of B. R. 84 even without benefit of hindsight. That he did not is a small, incidental mystery of his career. But like most prior accounts of introduced species, including some written by Elton himself, The Ecology of Invasions itself was an incidental work, a detour from its author's main ecological interests, an itch he finally had to scratch. It was written hurriedly, as if to clear his desk and mind of accumulated debris; and entertainingly, but certainly less coherently and deeply considered than his 1967 magnum opus, The Pattern of Animal Communities. As he confided to an American protege: 'I did the broadcasts I sent you copies of; am now turning that stuff into a 45,000-word heavily illustrated book for Methuens which I shall have written in nine weeks, ten days more to go, mostly about invasions and ecological interspersion, etc'. In that context, perhaps forty-one words were all Elton felt he could spare.