243 9. Beaches and Dunes Jörg Petersen Evert Jan Lammerts Saskia Mulder Gerard Janssen Iris Menn Wadden Sea Ecosystem No. 19 - 2005 244 Wadden Sea Ecosystem No. 19 - 2005 245 9.1 Beaches Saskia Mulder Gerard Janssen Iris Menn Beach plain on the island of Rømø with whithe dunes and typical tourism use (Photo: J. Petersen) 9.1.1.Introduction Assessment Program be adapted on the basis of During the Stade Conference in 1997 the Trilat- advice by an ‘Expert Group Beaches’. eral Wadden Sea Plan was adopted with common There are many different beaches all over the Targets for habitats species. The following Targets world: rocky beaches with boulders, cobbles or are valid for the habitat ‘Beaches and Dunes’: gravel and sandy beaches with coarse to very fine sand. Beaches in the Wadden Sea are sandy beach- es with a wide range of grain sizes. This chapter Targets will focus on the ecology of sandy beaches. A beach • Increased natural dynamics of beaches, pri- is defined as the area between low water level mary dunes, beach plains and primary dune and the first dunes on the North Sea side of the valleys in connection with the offshore zone. Wadden Sea islands. In contrast to studies of rocky • Favorable conditions for migrating and shores, the beach ecosystem was largely neglect- breeding birds. ed until Remane (1933) started studies of a shel- tered beach on the coast of Germany. Since then, several researchers have started studies on the In the 1999 QSR there was no chapter specif- ecology of sandy beaches in other parts of the ically focusing on beaches. It was stated that there world. But until a few years ago beaches in the is limited information about the present natural Wadden Sea were still unknown habitats. This, status of beaches and even less about temporal however, is about to change. Since 1998 research- developments. No conclusions on Target imple- ers in Germany and The Netherlands have made a mentation and recommendations for manage- start with beach ecology studies, which are mainly ment, monitoring and research in relation with concentrated on the relation between morphody- beaches were included. This was probably caused namic parameters (e.g. grain size, beach slope, by the lack of research programmes on beaches in wave energy) and abundance and species diversi- the Wadden Sea. For the QSR of 2004 data ob- ty of benthic fauna. tained from recent beach ecology studies in Ger- 9.1.2 Beaches as ecosystems many, Denmark and The Netherlands was limited, but nevertheless used to describe and evaluate Short and Wright (1983) describe a number of the status of beaches in the Wadden Sea. It was sandy beach types with different morphodynamic concluded that evaluation of the Target is not characteristics. Three basic beach types can be possible because of the lack of information about identified: reflective, intermediate and dissipative. the natural status of beaches in the Wadden Sea. Reflective beaches are characterized by coarse It was recommended that the Target should be sediments, a steep beach face, a narrow beach and reconsidered and the Trilateral Monitoring and the absence of a surf zone. Dissipative beaches show fine sediments, a flat beach face, a wide Wadden Sea Ecosystem No. 19 - 2005 246 9.1 Beaches beach and surf zone. Intermediate beaches repre- diversity and abundance at mid tidal level (MTL) sent a transition between reflective and dissipa- and very few species in low numbers at high wa- tive beaches. The morphodynamic characteristics ter level. The most dominant species on Dutch form the basic conditions for the ecological sta- beaches are the bristle worm Scolelepis squama- tus of the beach. Species diversity and abundance ta, the isopod Eurydice pulchra and the amphipod in general show an increase from reflective to dis- Haustorius arenarius (Janssen and Mulder, 2004). sipative beach state. In a study by Menn (2002a, b) the effects of Due to the dynamic circumstances the inter- eroding and accreting conditions on the food web tidal area of sandy beaches is inhabited by spe- structure of beaches were determined. The erod- cially adapted invertebrate species. An important ing shore (Sylt/Germany) is coarse grained, steep- group of the interstitial fauna is the meiobenthos, ly profiled and receives high wave energy, while which probably represents a food source available the accreting shore (Rømø/Denmark) is fine to macrobenthos. The macrobenthic invertebrates, grained, flat profiled and receives less wave ener- of which some can also be found in the surf zone, gy. The former resembles dynamic intermediate play an important role as food for young fish (e.g. beach types, and the latter a dissipative beach type sole), shrimp and birds. Birds such as the sander- (Short and Wright 1983). The study showed that ling, protected under the EC Birds Directive, de- on the eroding, intermediate shore with high wave pend for their food on macrobenthos species that energy meiobenthos is abundant, while macro- live near the dynamic water line and for the ken- benthos, epibenthic predators, fish and shorebirds tish plover and Little tern (red list species) the are all impoverished. On the accreting, dissipative upper part of beaches is a breeding habitat. shore with low wave energy, meiobenthos is also abundant, but with a different species composi- 9.1.4 Beaches in the Wadden Sea tion. Macrobenthos, epibenthic predators and Most sandy beaches are situated on the North Sea shorebirds are abundant. side of the Wadden Sea islands. In the vegetation Beaches, however, are not always either reflec- typology developed for dunes of the Wadden Sea tive or dissipative. Beach character may change unvegetated beach plains, beach driftlines and with the season as shown for Spiekeroog, which embryonic dunes are distinguished (see chapter had a reflective beach profile in summer and a 9.2 ‘Dunes’). Beaches show differences in width, dissipative one in winter 1986 (Flemming and slope, grain size and exposure. This results in dif- Davis (1994). How this dynamic behaviour influ- ferences in invertebrate macro- and meiobenthos ences meio- and macrobenthic infauna is not well species composition and abundance (Mulder, known. 2000; Menn, 2002; Janssen and Mulder, 2004). In The Netherlands, beaches range from dissi- 9.1.5 Human activities and impacts pative to ultra-dissipative. Beaches on the Wad- on the Targets den Sea islands of Schiermonnikoog and Texel are According to the Trilateral Wadden Sea Plan (1997) mainly ultra-dissipative, which means that macro- trilateral policy for beaches takes into account the benthos diversity and abundance are relatively demands of recreation and tourism, coastal pro- high on these beaches compared to beaches of tection and natural values, such as high geomor- the Dutch shores in the southern part of The Neth- phological dynamics and important breeding ar- erlands. There is a clear pattern of zonation of eas. Where possible, the natural situation should macrobenthic species composition and abundance be enhanced or restored by ‘hands-off manage- in the intertidal area of a beach, with maximum ment’. Table 9.1.1: Target 1 Target 2 Possible impacts of human Activity Increased natural dynamics Favourable conditions for migrating activities on the beach and breeding birds Targets. Beach nourishment Temporal change in natural dynamics Disturbance of migrating of the beach. and breeding birds. Nearshore nourishment Temporal change in natural dynamics Possible food disturbance of of the nearshore and beach. migrating and breeding birds. Hard construction Definitive loss of natural dynamics of the beach and change in natural dynamics of the nearshore. Recreation Disturbance of migrating and breeding birds. Wadden Sea Ecosystem No. 19 - 2005 9.1 Beaches 247 Activities aimed at coastal protection, such as necessary management measures. Furthermore, beach and nearshore nourishment and the build- natural dynamics of a beach is not a quantifiable ing of hard constructions, are necessary to pro- parameter, which is an important aspect of a tar- tect the inhabitants on the Wadden Sea islands. get. Finally, there is no general consensus on the To be able to apply Best Environmental Practice, definition of natural dynamics, nor on the meth- which is mentioned in the Wadden Sea Plan, in- ods to describe its status. sight in the possible impacts of these activities on the Targets is needed. These impacts, together with 9.1.7 Conclusions impacts of recreation, are mentioned in Table 9.1.1 Currently, there is no information about the actu- ‘beach nourishments’, having relatively short term al status of beaches in the Wadden Sea. TMAP negative effects on local meio- and macrozoob- does not provide information about beaches and enthos, can be regarded as an acceptable method only very recently were research programs on the for coastal protection, provided that some inter- ecology of sandy beaches started. An evaluation val years are kept between successive nourish- of the Target can therefore not be made. ments to allow for recovery of these infaunal pop- Nevertheless, growing human impact due to ulations (Menn et al., 2003). increasing activities concerning coastal defence, Draining of beaches, developed in Denmark as as a consequence of climate change, as well as an alternative way of beach protection and ap- increasing recreational activities, imply an urgent plied on the west coast of Jutland (Jakobsen, 2003, need for information and reconsideration of the 2004) may, however, significantly affect the in- Targets for beaches.