Swarming of Hyperiid Amphipods Apparent Photosynthesis

100 NATURE, VOL. 215, JULY 1, 1967

In Actinosphaeritum the twelve radial lines of microtubules 110 specimens, all but five being sexually mature or would presumably isolate the active sectors from one nearly mature, many of the females carrying eggs or another. young. As in the 1966 invasion, the composition there fore suggested a reproduction phase although the species A. MACDONALD c. in the two invasions were different. J. A. KITCillNG It appears that the neritic species•, Parathemisto graci School of Biological Scienc€'s. lipes, is generally the most usual one in the southern University of East Anglia, North Sea•, although difficulty in nomenclature tends to Norwich. cmuuse this1•.n. Thus the presence of P. gaudichaudii might be considered unusual and, considering its normal Booeived February 24, 1967. oceanic existence1 •8, indicative of an influx of water from 1 Kitching, J. A., in Primitive Motile Syste~M (edit. by Allen. R. D. , and the Atlantic Ocean. Similarly, swarms of the pteropod, Kamiya, N.), 445 (Academic Press, New York). Limnacia lesueuri, and of the radiolarian, Phyllostaurus • Kitching, J. A., and Craggs, 8., E<~England in the late summer and 2 • Grlmstone, A. V. , and Klug, A. J., OeU Sci. ,1, 351 (!966). early autumn of 192P • These organisms were 'Gall, J . G., J. OeU Bia.,P/1, 32A (1965). considered to have been carried around the north of 'Grimatone, A. V., and Cleveland, L. R., J. OeU Biol.,24, 387 (1965). Scotland. More frequently, successive swarms are brought only as far as the north of Scotlandu. In 1965, for Swarming of Hyperiid Amphipods example, the euphausiid Thysanoe88a longicaudata, which is normally oceanic, was found swarming in Lerwick FoLLOWING a period of moderately strong westerly wind, Harbour in the Shetland Isl,mds, where one would expect on June 26, 1966, the beaches of Robin Hood's Bay, Filey. T. inermi8 or T. rashi13• Here, as with the amphipods, and Sandsend, Yorkshire (extending for about 40 km of the swarm was in a reproductive state and is believed to coastline), were turned white by a covering of vast numbers have been influenced by local wind conditions. of hyperiid amphipods. The Sei whale in the Antarctic is reported to feed A sample of these was found to consist offift.y-six large almost exclusively on Parathemisto gaudichaudii•, and the specimens, all but two being sexually mature or nearly tunny (Thunnus alalunga) is known to feed on immense mature, and more than a hundred small juvenile specimens. surface swarms of this species (as Euthemisto compre88a) The large specimens were identified as Parathemisto which occur beyond the continental shelf off the French (Euthemisto) gaudichaudii (Guerin), both the compre88a Atlantic coast•. The cod off Langenes, Icelandu, and off 1 15 and bispinosa forms being present in about equal pro Bear Island , has been reported to take Parathemisto portions. The small specimens could be identified with oblivia (prob. = P. aby88orum) on some occasions as its certainty only as Parathemisto sp., but considering that predominant food_ The feeding to gorging, as shown for all of them were curled, as within the maternal oostegites, the cod off the Yorkshire coast, however, is here reported it was obvious that they had just been released. for the first time. Specimens of Parathemisto had occurred previously in This investigation was partially supported by a contract small numbers in April and May 1966. In early June, between the Scottish Marine Biological Association and mature specimens (containing young) were common in the US Office of Naval Research. the surface plankton off Sandsend. Following the invasion J. s. GRAY of the shore, large numbers of small specimens of Para Wellcome Marine Laboratory, themisto were taken in July in plankton hauls off Sandsend Robin Hood's Bay, and only rarely were specimens taken later in the year. Yorkshire. Thus swarming appears to be associated with the repro R . A. McHARDY ductive phase. Oceanographic Laboratory, On June 17, that is, before the invasion, the stomachs 78 Craighall Road, of cod (Gadus morrhua) of 33-60 em length trawled in Edinburgh. 14m of water, 1·2 km off Sandsend, were all found to be distended with specimens of Parathemisto gauiichaudii Booeived December 21, 11166. (identified by J. E. Kane). The cod were in large numbers 1 Kane, J. E., Disc. Rep., 34, 168 (1966). 'Bigelow, H. B.,Bull. U.S. Bur. Fi.911. , 40(2),1 (1924). and it seems likely that the amphipods had been swarming. 'Fish, C. J., and Johnson, M. W ., J. Bia. Btl. Oan., I, 189 (1937). Swarms of Parathemisto gaudichaudii have been reported 'Le Danols, l!l., Mem. Off. Sci. Tech., Pull. Marit., 9, 16 (1921). on other occasions; for example, off the Gulf of Maine1•3, 'Nemoto, T., Sci. Rep. Whale• Bes.!nn.,14,149(1959). off the French Atlantic coast• and in the Antarctic 'Hardy, A. C., and Gunther, E. R., Disc. Rep.,ll,l (1935). ' Ritchie, J., Nature, 91, 398 (1918). Ocean5 •8 • Where examined4 •5, as in the present case, the 'Bowman, T. E., Proc. U.S. Nal. Mt18., 112 (3439); 848 (1960). composition of the swarms showed them to have been in 'K1lnne, C., Ber. DeuUcll. Wu•. Kmnm. Meerufursch., 8 (3), 131 (1937). a reproductive phase. "Marshall, N. B., Hull Bull. Mar. Eool.,2 (18),173 (1948). The coastline discussed faces north -C'ast and the 11 Southward, A. J ., J. Mar. Bia• .A.u. U.K., U, 275 (11162). residual tidal current is south-east. Westerly winds 11 Hardy, A. C., Oom. Perm. Int. E"'f)lor. Mer. Puhl. Oirc., No. 78, 1 (1923). activated by the Coriolis force might have intensified the "Forsyth, D. C. T., and Jones, L. T., Nature,m, 1467 (1966). " Brown, W . W., and Cheng, C., Hull Bull. Mar. Eeol., 3 (18), 35 (1946). south-easterly current and brought the swarming amphi "Brotsky, V. A., Rep. Firat Se•sion State Ocea?Wgf'. Imt. Moscuw, 4, 20 (11131). pods closer to the beaches. A similar invasion occurred in May 1913, also following a J)eriod of westerly wind1 • Other invasions in February 1892, April 1907 and April Apparent Photosynthesis and Respiration in 1908 followed periods -of more directly onshore winds, Populations of Lolium perenne from Contrasting north or north-east. Thus it is quite possible that the prevailing wind in each case could have cont.ributed to ClimatiC Regions the invasion of the shore by the swarming amphipods. 1\fEASUREMENTS of net assimilation rate by growth analysis A sample collected from the beach at Redcar, York techniques have shown significant differences between shire, in April 1907 by T. H. Nelson was referred to as North European and Mediterranean populations of Euthemisto compre88a by Ritchie', and noted as Euthem Dactyli8 glomerata in controlled environments at low and isto compressa (Gol!s) var. gracilipes Norman (Reg. No. high temperatures', and between a similar range of 1907-79, Royal Scottish Museum). According to modem populations of D. glomerata, Festuca arundinacea and usage this species is Parathemisto (Euthemisto) gracilipes•. Lolium perenne in the winter, spring and autwnn at On re-examination, this sample was found to consist. of Aberystwyth2• Greater net assimilation rates were found