A study of the invertebrate fauna and crustacean zooplankton of the Shropshire union canal and the Llangollen canal
Five sites were chosen on the main Shropshire Union Canal\ud and three on the Llangollen Canal. Monthly quantitative samples\ud of the bottom fauna. shore fauna •. and crustacean zooplankton were\ud 'taken from all sites over a period of 24 months from the Shropshire\ud Union Canal. and over 18 months from the Llangollen Canal.\ud An account for the topography and the geographical location\ud of the sampling sites on the Shropshire Union and Llangollen Canals\ud are given. for it is believed. that these are important and affect\ud the physical conditions of the·canal waters.\ud Sampling apparatus and procedures are described suitable for\ud quantitative collection of the bottom-fauna. shore-fauna and\ud crustacean zooplankton of the two canals. including the sites with\ud rough and uneven bottoms.\ud Experiments were done. as a further contribution on the\ud assessment of the accuracy of the dredge. Which was designed for\ud sampling the bottom fauna of canals.\ud 2.\ud The qualitative and quantitative composition of the invertebrate\ud ,varied with season and prevailing physical and chemical conditions.\ud The seasonal qualitative and quantitative changes of the more\ud common invertebrates are described. Monthly size frequency\ud distributions of the more common species are illustrated graphically\ud and in tables.\ud The water chemistry of the two,canals was investigated by\ud collecting samples from all sites. The results obtained by\ud standard analytical techniques showed that the following\ud constituents all exhibited definite gradients along the cana1:-\ud PH, Total hardness, Calcium and Magnesium concentrations (as mg\ud per litre). These constituents showed a difference in concentration\ud from one site to another.\ud The Llangollen Canal water chemistry was significantly.\ud different from the Shropshire Union Canal.\ud Undoubtedly, many reasons for the restriction of any particular\ud species to a particular environment lies in the basic chemical and\ud physical features .pertaining to that environment.\ud described and discussed in results and discussion.\ud These have been\ud Some groups, (notably Tubificidae, Chironomidae larvae and\ud pupae,Limne.phllidae larvae) could not be fully identified within the\ud scope of this study. The general composition of the invertebrate\ud fauna at all sites can be seen in the tables.\ud The work provides guide linQs which might be profitably used in\ud investigating the life cycle of some Eph~meroptera, Trichoptera and\ud Hemiptera. It should also be useful for work concerned with\ud maintenance of fish and fish food organisms and the assessment of\ud pollution in canals.