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Marine Pollution Bulletin 54 (2007) 1673–1676

Editorial

Fifty years of change

First of all, I would like to thank our colleague CharlesSheppard sincerely for his invitation to join the EditorialBoard of the international journal, Marine Pollution Bulle-

tin. Joining this board is a great pleasure, and makes mevery proud for several reasons. In fact, my first interna-tional scientific paper was published in MPB (Cabiochet al., 1978) nearly 30 years ago while I was still writingmy dissertation; this was in 1978, the year the AmocoCadiz foundered off the Brittany coast. In the interveningyears, I have been published in this journal on several occa-sions, and I am currently an active participant in the debateabout the use of benthic indicators in the implementationof the European Water Framework Directive.

I know the Cotentin peninsula, about 50 km north ofMont Saint Michel Bay in France, very well, both frombeing born there (at the beginning of the 1950s) and fromspending time there each year. The tidal range there is13 m during equinox’s spring tide, and the area’s sandybeaches, with their large intertidal zones can reach 5 kmwide at spring tides. My own experience has confirmedboth the resistance and resilience of this megatidal littoralzone, and especially the need to take the historical recollec-tions of ordinary people—most of whom have importantevents inscribed in their memories—into account to helpto track long-term changes in the coastal environment.Over the last fifty years, natural and anthopogenetic eventshave affected this littoral region, as is the case for othernorth-eastern European countries. During this half a cen-tury, many things have changed, but still others remainthe same.

The first remarkable event in this area was the very coldwinter of 1962–1963. During this period, the sea froze atlow tide and all the wetlands and salt marshes were coveredin ice for several weeks, resembling winter weather patternsof Northern European countries more than those ofFrance. Especially in the intertidal zone, catastrophic mor-talities occurred in several species of mollusc, such as thecommon octopus Octopus vulgaris and the warty venusVenus verrucosa, as well as many other invertebrates andseveral fish species, such as Conger conger. In spite ofclimate changes (e.g., increased sea temperatures since the

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doi:10.1016/j.marpolbul.2007.09.035

beginning of 1980) that make environmental conditionsmore favourable to many species nowadays, O. vulgaris isstill absent from these waters, even after 45 years. Con-versely, the population of V. verrucosa has come back toits original levels, despite smaller decreases during the coldwinters of 1978/1979, 1985/1986 and 1995/1996. This spe-cies is now very common and is fished regularly at low tidefrom September to April (maximum authorized: 100 spec-imens per person and per day).

A secondary impact of this cold winter (1962/1963) wasa very high summer recruitment of the blue mussel Mytilus

edulis on most of the rocky shore, probably due to avail-able space on the substratum following high winter mortal-ities among algae and invertebrates. This naturalsuccession encouraged the introduction of mussel farmingalong this coastline at the end of the 1960s. Ten years later,at the end of the 1970s, a second species—the Pacific oysterCrassostrea gigas—was introduced in this area followingthe decimation of the Portuguese species Crassostrea angu-

lata (in fact they are the same species!) by disease. Today,the mussels and oysters of the west coast of the Cotentinpeninsula are famous, and this section of the littoral consti-tutes, respectively, 20% and 25% of the French mussel andoyster stocks (Kopp et al., 1998). Thus, this climatic event,and its ecological consequences, has had a positive effect onthe region’s economy, which explains why the human pop-ulation stabilized and grew after decreasing dramaticallybetween 1950 and 1970. Clearly, the region, which wasdepopulated following the Second World War, experiencedan increase in its permanent population (1980 to the pres-ent), with a consequent increase in diverse sectors (e.g.,construction, transportation, commerce). These variousactivities in turn increased the economic input.

Bivalve farming alone created 3000 jobs. When musseland oyster farms were first introduced, some people contin-ued in their current occupations (e.g., artisan, farmer, re-tired person), but added a second activity to promotemollusc farming. Over time, to comply with French andEuropean hygiene rules and regulations, mussel and oysterfarming was professionalized. As a result, these bivalvefarms, especially oyster farms, introduced several exotic

1674 Editorial / Marine Pollution Bulletin 54 (2007) 1673–1676

species, such as the sea squirt Styela clava. The invasiveJapanese brown algae, the Sargasso weed Sargassum muti-

cum, was also introduced, resulting in the colonization oflarge areas of the intertidal zone where the seawater re-mains at low tide. This inadvertent introduction has hada negative impact not only on oyster farming, but alsoon boat circulation.

Other biological consequences of bivalve farming in-clude increased populations of gastropods, such as the car-nivorous rocky shore gastropod mollusc Nucella lapillus

and the oyster drill Ocenebra erinacea, which feed on bothmussels and oysters. In addition, during their winter migra-tion (January–March), groups of common eider ducks(Somateria mollissima) remain a long time near the woodenfences of the mussel farms, each duck consuming severaldozen individuals per day. Since these feeding practiceseat into the mussel producers’ profits, in effort to preventthe eider duck predation, these producers pay people torun two small boats around the mussel-laden fences at hightide to frighten birds by firing guns. The transport of oys-ters between the different production centres along theFrench coast, from Arcachon and Marennes-Oleron tonorthern and southern Brittany, also helps to disseminateand proliferate another introduced species, the gastropodCrepidula fornicata. In some places with low hydrodynamicactivity between the sand and gravel banks, live and deadindividuals accumulate in the inter-bank zones in layersseveral dozen centimetres thick.

In addition to these biological consequences of new bi-valve farming, these activities also have hydrodynamic im-pacts due to the presence of wooden fences necessary formussel farming and of iron tables with their mesh bagsfor oyster farming. These structures encourage sedimentto accumulate near the production zone and provoke beachand dune erosion. It is now necessary to reinforce dikes andto transport sand in an effort to revitalize the beach in or-der to insure the protection of the natural dunes and arti-ficial dikes in tourist areas. Since the beginning of the20th century, there has been a trend towards the construc-tion of second homes near the shore, but a rapid increase inthe number of new constructions has been observed sincethe beginning of the 1980s. Politicians and policymakersare nowadays very responsive to arguments for the devel-opment of tourism on and around such beaches and arenot very inclined to accept the scientific arguments that itwould be better to let nature take its course in zones suffer-ing dune erosion.

Another consequence of bivalve production is the secre-tion of pseudo-faeces, which deposit on hard substratesand which is disastrous for the recruitment of some algae,such as the red algae Chondrus crispus. This alga used to becollected to produce alginate and agar-agar, but collectionceased in the 1990s. Other algae (e.g., the bladder wrackFucus vesiculosus and the serrated wrack Fucus serratus)have traditionally been collected to fertilize grasslands,due to their input in natural nitrogen, potassium and cal-cium. However, they ceased being collected in the 1980s,

not for the same reason as C. crispus, but rather becausethe farmers prefer to use artificial nitrogen and phosphorusnutrients. The disease of the eelgrass Zostera marina, whichwas traditionally used for bedding (mattresses and pillows)notably during the First World War, ceased at the end ofthe 1950s. The end result of these changes is that the collec-tion of seaweed and eelgrass along the littoral in this areahas been totally abandoned in the last 30 years.

Another traditional activity—traditional wooden fisher-ies—has also disappeared over the last few years in favourof a more developed fisheries industry. Decreasing fishpopulations in the English Channel caused the disappear-ance of these traditional fisheries, thought to contributeto the mortality of young fish.

The increased human population along the littoral hasintensified the use of freshwater and the need for watertreatment plants. Insufficient water treatment in urbanzones and excess nitrogen input in fields has generated localeutrophication along the littoral near the mouth of manyrivers. Local increases of the Ulva spp. and microbial pol-lution at some beaches have been observed, resulting in aban on low-tide fishing in the impacted areas. Nevertheless,due to the megatidal regime in this part of the Channel, thepollution remains confined to small local areas, and sincethe water is highly mixed in such megatidal systems, thispollution does not affect the quality of cultivated mussels,oysters and other bivalves, like it does the quality of crus-taceans and fishes. Another problem for bivalve cultivationcomes from the organic pollution due to sheep faeces. Thetraditional animal husbandry activity in the salt marshesaround Mont Saint-Michel Bay and the eight small estuar-ies along the western coast of Cotentin is sheep farming;these sheep (17,000 individuals) pollute the coastal watersthrough the input of organic matter from the salt marshes.Once again, conflict has arisen between traditional activi-ties and the new occupations in the littoral. However, thefarmers around Mont Saint-Michel Bay have now obtainedthe AOC label (Appelation d’Origine Controlee), which willimpose new limitations on the total number of sheep graz-ing in the salt marshes at the same time and on the numberof grazing days.

Given the success of the M. edulis and C. gigas introduc-tions, a third species—the manila clam Tapes philippina-

rum—was brought in for cultivation. This newintroduction was a big success; the species colonized a largesection of the mediolittoral zone, particularly the upperpart of the zone. It supplanted the autochthonous species,the carpet-shell Tapes decussatus, which had been decreas-ing since the 1960s, mostly due to the after effects of thecold winter of 1962/1963, but also probably to over fishing.

In France, the national government remains the soleauthority for enforcing the Maritime Public Domain lawsand regulations. So, when the T. philippinarum began toproliferate and offer a new resource accessible at low tide,the State instituted statutes governing low-tide fishing bynon-professionals, including regulating the season length,fish size and number, and the tools authorized for this

Editorial / Marine Pollution Bulletin 54 (2007) 1673–1676 1675

recreational activity. At the same time, a professional sta-tus was accorded for professional low-tide fishermen. Inthis way, customary practices have changed over time, withthe substitution of licensed professionals for the traditionalpractice of citizens from littoral communities, who have en-gaged in maritime fishing from time immemorial as a foodresource and income supplement, and tourists, who cometo harvest shrimp, clams, decapods and fish at each lowtide during the spring tides. More than 1000 people canbe counted on every beach during the spring tides of thespring/autumn equinoxes in March and September. Inspite of the regulations governing the number and size ofharvested species, the catch during such a spring tide isconsiderable, probably larger today than in times gone bywhen a number of experienced people with appropriatetools harvested without target species limitations. In thespecific case of the manila clam T. philippinarum, the limi-tation on the number of individuals harvested (100 per dayper fisherman) is surprising given that it is an exotic oppor-tunistic species that has supplanted the indigenous speciesT. decussatus.

In spite of the changes over the last 50 years, certaincommercially viable species (e.g., the lobster Homarus

gammarus, the edible crab Cancer pagurus and the velvetswimming crab Necora puber) have maintained their popu-lations with periodic fluctuations, and today the regula-tions governing such catches seems sufficient to ensuretheir renewal over time. This is unfortunately not the casefor the necrophagous gastropod common whelk Buccinum

undatum, which has been subjected to heavy fishing formany years. Today, the stock in the primary site in France,the Normano-Breton Gulf, is seriously depleted. In re-sponse to this depletion, several drastic stock managementmeasures were taken: limitations were instituted in thenumber of fishing days per week (5) and per year (about220), as well as the number of kg per fishermen (300 kg).

There have been some signs of rising sea temperatures,including the success of the T. phlilippinarum colonies;the summer catch of warm temperature fish, such asBalistes balistes; and the possible reproduction of theoyster C. gigas, with an important recruitment on the hardsubstrates of the intertidal zone in certain years (e.g., 2003).This phenomenon is less important along the westernCotentin coast than in other French littoral zones, suchas the Bay of Brest in Brittany, but it does exist (Hilyet al., 2007).

In summary, over time, changes occur not only due tonatural conditions (e.g., cold winters, increasing sea tem-peratures since the 1980s) but also to significant anthropo-genic influences on this littoral. The maritime territory isincreasingly a space for organized economic activities, suchas professional low-tide fisheries and bivalve farming, andfisheries regulations have become more and more universal.The intertidal zone at low tide, which was traditionallyused by the littoral population to supplement food re-sources and income, is now home to commercial ventures(e.g., mussel and oyster farms) and recreational activities

(e.g., swimming, windsurfing, jet skis). Still, some tradi-tional activities have persisted over time, such as low-tidefishing and sheep farming. The reality of this combinedpresence of new and old activities demonstrates the abilityof the marine coastal system to adapt to both natural andanthropogenic pressures.

However, the resistance and resilience of these strug-gling environments cannot be expected to continue indefi-nitely. The multiple and diverse activities carried out insuch environments need to be taken into account in orderto institute better coastal zone management practices. Anational program of Integrated Coastal Zone Managementwas proposed by the French national government in 2005,and one of the 25 projects chosen took place on this wes-tern Cotentin coast (Guineberteau et al., 2006). The resultsof this project will be interesting for future planning. How-ever, more is needed. France, like every country borderinga marine body, sponsors a lot of long-term observations inlocations near such marine stations as Plymouth, Roscoff,and Helgoland, to cite some of the more important stationsalong the English Channel and the North Sea. (See, forexample, the paper by Southward et al. (2005) about thestrategy employed at the Plymouth Observatory.) Butlong-term scientific observations are few and far betweenfor large sections of the littoral. I think that an opportunityexists today for the Human and Social Sciences (e.g., soci-ology, history, ethnology) to conduct large surveys de-signed to gather information from the people living andworking along littoral, including but not limited to fisher-men. These people have many unrecorded memories thatcould help to improve our understanding the primarychanges along our littoral zones. Local studies by naturalistsocieties, often published in the gray literature, could alsocontribute to the body of observed changes in the seashore.

References

Cabioch, L., Dauvin, J.C., Gentil, F., 1978. Preliminary observations onpollution of the sea bed and disturbance of sub-littoral communities innorthern Brittany by oil from the ‘‘Amoco Cadiz’’. Marine PollutionBulletin 9, 303–307.

Guineberteau, T., Meur-Ferec, C., Trouillet, B., 2006. La gestion integreedes zones cotieres en France: mirage ou mutation strategique fonda-mentale? VERTIGO 17 (3), 1–14.

Hily, C., Lejart, M., Miossec, L., 2007. The invasion of the Atlantic andChannel coasts of France by the alien oyster Crassostrea gigas:assessment, causes, ecological and socio-economical consequences.The PROGIP programme. In: Poster at the Fifth InternationalConference of Marine Bioinvasions, Boston, 21–24 May 2007.

Kopp, J., Joly, J.P., Le Gagneur, E., Ruelle, F., 1998. Atouts etcontraintes de la conchyliculture normande. 1. La Cote ouest duCotentin. Rapport DRV/RA/RST/98-08, Ifremer Port-en Bessin,240p.

Southward, A.J., Langmead, O., Hardman-Mountford, N.J., Aiken, J.,Boalch, G.T., Dando, P.R., Genner, M.J., Joint, I., Kendall, M.A.,Halliday, N.C., Harris, R.P., Leaper, R., Mieszkowska, N., Pingree,R.D., Richardson, A.J., Sims, D.W., Smith, T., Walne, A.W.,Hawkins, S.J., 2005. Long-term oceanographic and ecological researchin the Western English Channel. Advances in Marine Biology 47,1–105.

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Jean-Claude DauvinStation Marine de Wimereux,

Universite des Sciences et Technologies de Lille,

FRE CNRS ELICO 2816,

28 avenue Foch, BP 80, F-62930 Wimereux, France

Tel.: +33 321 99 29 20; fax: + 33 321 99 29 01

E-mail address: jean-claude.dauvin@univ-lille1.fr