conspicuous to predatory newts. This idea was put forward by Dr A. S Cooke at the Monks Wood Experimental Station m Huntmgdonshlre (Nature, 2°9, 275, 1971) after he had observed that tadpoles treated with DDT at low concentrations swim frantacally for a whde and then become ~reslgned', swmammg conUnuously but m a slow twasung manner. Eventually they the. Dr Cooke has p r o d u c e d evidence that suggests that the attention of newts is caught more by the unusually active tadpoles than by those swimming normally He placed a warty newt m a glass tank together with two tadpoles, one wath a known a m o u n t o f DDT in ~ts ussues and m a frant,c state, and the other wathout DDT, swimming normally He watched the newt as ,t stalked the tadpoles and recorded the survasal rates of the two types The newt went cons~stentlv for the DDT-treated tadpole. One explanation for thas would be that the treated tadpoles are obhvmus of the fact that they are being pursued and take no evasive actmn, but Dr Cooke thinks that such a factor would be counterbalanced by their uncoordanated and unprechctable movements To him, it seems more hkelv that ~t is their greater conspicuousness that renders them eas,er pre~ for the newt. The c o m m o n frog has decreased m numbers m eastern England m recent years and at has been suggested that, whale the mare cause ts probably the loss of statable ponds m the frog habitat, pesuc,des m a y be partly responsible. Their chaef effect on the tadpoles ~s hkely to be dxrect and lethal rather than of the kind d e s c r i e d by Dr Cooke, but the sublethal, mchrect effects, ff they do not affect the tadpole p o p u l at m n as a whole, may well be an adchuonal hazard to the mdavxdual anLmal
Oiled Birds in Holland On 29 December, 1970 approxamately 16,000 tonnes of heavy fuel oil was released from a fractured storage tank at a power stauon between Drmamelen and Gertruidenberg, m Holland. In spite of a retaining dyke, some 12,000 tormes of this od polluted the waterways o f part of the Blesbosch, a low l~mg roland delta area where the rwers Maas and Waal come together. A consxderable n u m b e r of ~aldfowl were ogled m this pollution incident, and during the hrst ten days after the oil had been released some 50 heavdy oded birds (rrmmly swans, ducks, geese and coots) were taken by a local btrd-cleamng organization (Suchtmg voor VogelOheslachtoffers te ~vqaardmgen - Marzne Pollutmn Bulletin 1, 156, 1970) to an ananal welfare centre at Vlaarchngen. Here a new cleamng m i x t u r e was used to r e m o v e part of the od, and any remaining on the feathers could be rinsed away later as a stable emulsion m water, an maportant c o m p o n e n t of the cleaning rmxture was a biologacally 'soft' non-iomc detergent. This technique o f cleaning followed by rinsing was very successful, although in practice a h m m n g factor was the a m o u n t of water avadable m which the od-m-water emulsmn could be rinsed from the feathers. Resadual emulsified oil could be r e m o v e d bv further rinsing, or by wiping wath a damp cloth or sponge. As m many denning exercases, a lack of facihues must reduce operauonal success, and m this instance facthties for rinsing and drymg the birds were being improved. It wall be most interesting to follow the success m rehabzhtatmg birds cleaned by th,¢ m e t h o d , since the techmque was particularly effectl),e m removing the large amounts of contamanatmg od. However, techmques revolving detergents which are adsorbed at the feather surface render the feather hvdrophahc, and m the short-term this state may be onl~ partly reversed by rinsing in water. Whde n is to be hoped that non-ionic detergents wall leave the
plumage m a non-wettable conchtion, p r e h m m a r v tests sslth single feathers mdscate that tlus will not be the case. In practice, washing with a detergent is one of the simplest ways of removing oil from a bwd's plumage, whzle residual detergent remaining an the feathers after rinsing ~s, m m a l l v , a major factor responsible for the cleaned plumage wetting. Water-soluble m m c detergents may be neutrahzed bx certain orgamc amines, and the posslbdit~ of rendering feathers h~ drophobic m tlus way is being investigated. Advisory Committee on Od Pollutaon of the Sea O,led Seabzrd Research Unit, Department of Zoologs, Umversn~ of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, U K.
K G Gregorx
Pollution by Synthetic Fibres In the course of routine e x a m m a t l o n of suspended matter from the sea area adjacent to the south Northumberland coast, it has been observed that large quant~tles of s v n t h e u c fibres form a constant and apparently increasing feature of the materml concentrated when water samples are membrane-filtered. The fibres are present m water samples taken at all depths from 0 -- 100 m and m the inshore waters may occur at concentrations o f 50 -- I 0 0 mchvldual fibres per htze of water filtered. Since the hbres vary greatly m d~menslons, attempts to quantlfv thelr presence have at present had little success. Many of the fibres are strongly coloured - red, blue and orange fragments being of frequent occurrence. As well as m w~ter samples, the fibres are now b eco m m g an almost obligatory constltuent of 'mechum n e t ' plankton hauls, where fragments of larger chmenslons often form an embarassmg p r o p o r t l o n o f the f'dtered materml. . ~ t h o u g h it must be admitted that the lmpressmns are subjecuve, ~t seems very clear that th~s p h e n o m e n o n has become increasingly obvmus over the last decade. There seems to be httle doubt that the ongm o f the fibres hes m the increasing use of s y n t h e u c marine cordage and netting which xs n o w used almost exluslveR by the inshore fishing industry and m the manufacture of crab and lobster pots. The presence of fibres m suspended matter Is by no means unkno~na. Probably the hrst d o c u m e n t e d account zs gnven by ~.tkms et al (1954) from water samples from the English Channel. At this time, the fibres were ldenufied as manda, colt and jute, all natural fibres. The fibres f ound by McAlhster et aL (1960) at weather station 'P' m the Pacific were identified once again as of bmgemc o n g m (cellulose). It must be supposed that these natural fibres wdl be slowly bin-degradable with time. The s y n t h e u c hbres however create a more sermus problem in th,s respect and apart from mechamcal breakdown It seems probable that they may co n st n u t e a growing and cu m u l au v e constituent of low specffm gravzty materml in the suspended matter of inshore marine areas At present, efforts are bemg made to put the observauons on a quantitative basis. Dove Marine Laboratory, Cullercoats, North Shields, Northumberland, U K.
J B. Buchanan
Atkms, W R G . , J e n l ~ n s , P G. and Warren, F J 1954, The suspended matter in sea xsater ~J mar biol. Ass U K 33,497-509 McAlhster, C D., Parsons, R. R. and Stnckland, J D H 1960, Prlma~ production at S t a u o n 'P' m the northeast Pacific Ocean. 'J Consed Cons. Perm. Int. Expl Mer ' 25, 240-259 23