Qualitative Deeply Affect Predominant Ecological Factors
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Bijdragen tot de Dierkunde, 50 (1): 1-34 — 1980 Population dynamics of three gammarid species (Crustacea, Amphipoda) in a French chalk stream. Part I. General aspects and environmental factors by Annemarie Goedmakers Institute of Taxonomie Zoology, University of Amsterdam, The Netherlands Abstract 1. INTRODUCTION first of of describes This is the a series four, it the paper The of in range gammarid species a given body general outline of a research project on the ecology of Gam- fresh brackish of or water can vary considerably marus pulex pulex (Linnaeus, 1758), G. fossarum Koch in Panzer, 1836, and Echinogammarus berilloni (Catta, and sometimes shows vast changes. In estuaries, in small French chalk the Slack. The entire 1878) a stream, and tide and season deeply affect the distribution study investigates the impact of (changes in) environmental of et factors and of these three fresh- migratory pattern gammarids (Dennert al., on standing crop migration water gammarids. 1969; Girisch et al., 1974). A newly introduced An account is given of and biological physicochemical be successful in its species may very competition research methods used. Special methods to capture both with indigenous animals and thus replace these in drifting and upstream migrating gammarids were developed. this first data environmental factors are their habitats The In part, on original (Pinkster et al., 1977). presented with an emphasis on the seasonal and micro- marked environmental instability of a brackish geographic variation they show in this river. Detailed in- about a balance between formation about the diel variation of some environmental lagoon brings dynamic factors is given. two coexisting species (Janssen et al., 1979). After mathematical treatment of the data on environmental These phenomena, however, are all examples of factors Slack classified four unstable the is in zones: an distribution influenced by one or two headwater, a large stable upper/middle region, a rather patterns polluted lower region and an estuarine part. predominant ecological factors. The longitudinal zonation of freshwater species Résumé in a stream is the result of a complex interaction Cet article est le premier d’une série de quatre; il décrit between more than just one or two environmental le cadre d’un plan de recherches sur l’écologie de Gam- marus G. Koch The dif- pulex pulex (Linnaeus, 1758), fossarum factors. distribution of gammarids over in Panzer, 1836, et Echinogammarus berilloni (Catta, 1878) ferent stream habitats (Minckley & Cole, 1963; dans un petit cours d’eau calcaire du Boulonnais, la Slack. 1971; is L’étude entière recherche l’influence (du changement) des Roux, 1967; Meijering, Vincent, 1971) facteurs du milieu le et la migration de which makes them sur «standing crop» relatively stable, good indicator trois Gammares d’eau douce. ces for species, e.g. pollution. This stable type of Les différentes méthodes de recherches biologiques et distribution seems to be with rather physico-chimiques utilisées ont été décrites. Des méthodes conflicting bien particulières pour capturer aussi les Gammares migrant high migration rates observed within gammarid en aval qu’en amont ont été développées. populations (Waters, 1965; Lehmann, 1967; Dans cette première partie, les données sur les facteurs Elliot & Minshall, 1968; Hultin, Meijering, du milieu sont présentées avec l’accent sur les variations 1971; saisonnières et microgéographiques qu’ils montrent dans 1972). cette rivière. Les fluctuations nycthémérales de certains This study sets out to analyse the variation in décrites détail. facteurs abiotiques sont en distribution certain area of freshwater gammarids Après traitement mathématique des données sur les fac- du classifiée teurs la Slack a été en zônes: the and the factors that milieu, quatre throughout year cause, une zône marécageuse instable près de la source, une large et influence or regulate this variation. It tries to give stable inférieure partie supérieure et moyenne, une partie of a impression biological assez polluée et une zône estuarienne. qualitative processes 2 A. GOEDMAKERS - POPULATION DYNAMICS OF GAMMARIDS small details have The started in 1973 encountered in a river. Some to field program September while and Fifteen sta- be investigated more thoroughly, quantita- lasted till July 1976. sampling taken into tions chosen in the main stream with tive aspects have hardly been account. were an served the less stretches The research program two purposes: emphasis on polluted (fig. 1). the took of the firstly we came to know more about some poorly During first year we samples studied it offered estimated the diel biological processes, secondly a standing crop, migration activity broad scala of topics useful in teaching ecology. (both upstream migration and drift) and measured methods factors At the same time some new ecological a number of environmental every two The this could be tested. weeks at each station. next year sampling carried out month. program was once a Every ACKNOWLEDGEMENTS 2. three data months a special set of chemical was subsidized of The research project was by a grant present gathered. the Netherlands' Organization for Pure Scientific Research Each the variation in (ZWO) and the Foundation for Fundamental Biological sampling period hourly Research (BION), but could only be carried out as it was, migration as well as the variation in environmental the of the Institute of with assistance of many people measured 24 hours factors was during at a single Taxonomie Zoology in Amsterdam, both in the laboratory station. An week in the summer of and in the field. eight period Of all those people I especially would like to thank 1975 and a two week period in July 1976 of Mr. Herman Mittelberg, who made so ideas work and many continuous mensuration this completed program. Drs. Jan Dieleman for his technical help at the computer. During these two periods migratory activity was Prof. Dr. Jan Stock did all he could to obtain the grant and failed to back me Most I however, measured while the in environ- never up. grateful am, every hour, changes to Dr. Sjouk Pinkster, because it is doubtful whether this mental factors were continuously registrated. work would have been done without his practical and moral In know and this way we came to the daily support. annual variation in environmental factors, which could be correlated with the population dynamics 3. STUDY OUTLINE (distribution, life history, migration patterns etc.) French the A natural stream on the Channel coast, of the three gammarid species. chosen We have extend of certain river Slack, was as study area. In order to our knowledge the of environ- additional set up a program combining study aspects, we conducted some experiments mental of factors, life histories and migration pat- (like marking and releasing of special groups of three Gammarus numbers of carried terns gammarid species: pulex animals; counting eggs, by pulex (Linnaeus, 1758), G. fossarum Koch in females of each of the three species in their and berilloni and under Panzer, 1836, Echinogammarus marsupium; testing reproduction labo- (Catta, 1878), living in the limmic part of this ratory conditions) at various stages of the research river (Stock et al., 1966). project. Fig. 1. Map of the river Slack with the fifteen sampling stations. BIJDRAGEN TOT DE DIERKUNDE, 50 (1) - 1980 3 4. DESCRIPTION OF THE RIVER SLACK Station 2. Fouhen. — The Slack gets the character of fast streamlet. This station km a flowing The Slack is a stream of about 20 long, which is overshadowed shrubs and trees. At from heavily by runs east to west in the northwestern part ford the is this place, cattle often river, so it of France (Pas-de-Calais), a calcareous region shallow and muddy. called the Boulonnais. It is partly fed by chalk but and springs, mainly by seepage surface run- Station 2a. Fouhen spring. — At off. It debouches into the Strait of Dover just station 2 small chalk itself in the south of the of Ambleteuse. The a spring empties village upper Slack. It is constantly covered with Berula erecta reaches flow through low hills covered by farm- of and Nasturtium officinale, a vegetation typical land interspersed with hedgerows and small vil- spring regions in this of France. lages. It is polluted by human waste and bio- part industries. From the twin-towns Rinxent and Mar- Station 3. Le Fart. — This station is the lowland quise onwards, Slack becomes a small named after farm which houses a lying next to it, river, polluted by industrial effluent as well a small bioindustry. The river flows fast between sluice which (Hoestlandt, 1971). Due to a is low grassy banks. closed automatically by the incoming tide, the Slack has a semi-open estuary with tidal influences Station 4 . Héronval. — Héronval is upstream of this sluice (Dennert et al., 1969). one of the farms around this station. The waste The sites shown in fifteen sampling are fig. 1. of its quite sizable bioindustry (pigs, poultry) is discharged directly into the Slack. Often large Station 1. La Fontaine. This sam- trucks drive through the river at this site. One pling site is situated about 300 m downstream riverside is and grown by shrubs trees. of the main spring. (Unfortunately we were not take from allowed to samples the main source Station 4a. Héronval tributary. — which is used for watercress com- itself, growing Station 4a is situated in a small brooklet, 40 m mercially.) Most of the time the Slack here is upstream of the spot where it flows into the Slack merely a tiny trickling stream, flowing through On its flat meadows it is (fig. 4). way through open muddy grassland. In summer it is contaminated muck from cattle- completely by water many with Berula erecta ( = Slum erectum overgrown ), raising farmsteads to an even larger extent than Nasturtium and Veronica officinale beccabunga. the main stream at this point.