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Summary 1. Shoreline development and the associated loss of littoral habitats represent a pervasive alteration of the ecological integrity of lakes and have been identified as major drivers for the loss of littoral biodiversity world-wide. Little is known about the effects of shoreline development on the structure of, and energy transfer in, littoral food webs, even though this information is urgently needed for management and mitigation measures. 2. We measured macroinvertebrate biomass and analysed potential food resources using stable isotopes (δ13C, δ15N) and mixing models to compare the complexity and the trophic base of littoral food webs between undeveloped and developed shorelines in three North German lowland lakes. 3. The lower diversity of littoral habitats found at developed shorelines was associated with lower diversity of food resources and consumers. Consequently, the number of trophic links in food webs at developed shorelines was up to one order of magnitude lower as compared with undeveloped shorelines. 4. Mixing model analysis showed that consumer biomass at undeveloped shorelines was mainly derived from fine particulate organic matter (FPOM) and coarse particulate organic matter of terrestrial origin (CPOM). The contribution of CPOM to consumer biomass was twofold lower at developed shorelines, and consumer biomass was mainly derived from FPOM and suspended particulate organic matter. 5.Synthesis and application. Shoreline development impacts the flow of organic matter within littoral food webs primarily through the reduction in littoral habitat diversity. These effects are exacerbated by clearcutting of the riparian vegetation, which disrupts cross-boundary couplings between the riparian and the littoral zone. Lakeshore conservation should focus on preserving the structural integrity of the littoral zone, while restoration of coarse woody debris, reed and root habitats can be a cost-efficient measure to improve degraded lakeshores. The local effects of shoreline development demonstrated in this study might lead to whole-lake effects, but future studies are needed to derive thresholds at which shoreline development has consequences for the structure and functioning of the entire ecosystem.

Summary 1 The shores of many lakes have been substantially altered by human developments such as erosion control structures or recreational beaches. Such alterations are likely to increase in the future, yet almost nothing is known about their impacts on the littoral macroinvertebrate community. 2 Macroinvertebrates were studied in seven German lowland lakes exhibiting natural shorelines (reference), retaining walls, ripraps and recreational beaches to examine impacts on the eulittoral (0–0·2 m water depth) and infralittoral (0·2–1·2 m water depth) communities associated with the three types of shoreline development. 3 Among sites, eulittoral species richness and abundance of Coleoptera, Gastropoda, Trichoptera, shredders and xylophagous species were lowest on beaches and retaining walls but ripraps did not differ significantly from natural shorelines. Retaining walls and ripraps had no significant impact on the infralittoral macroinvertebrate community. Conversely, beaches had significantly lower infralittoral species richness and abundance of Ephemeroptera, Trichoptera and shredders than natural shorelines. Furthermore, species richness was correlated positively with habitat heterogeneity expressed as number of habitat types. 4 Among lakes, whole-lake littoral macroinvertebrate density increased with increasing proportion of developed shorelines due to increasing abundances of Chironomidae. The remaining macroinvertebrate major groups decreased with increasing proportion of shoreline development. 5 Synthesis and applications. The biological impacts of shoreline development in lowland lakes depend upon the extent to which structural complexity and heterogeneity of littoral habitats are reduced. Hence, we recommend that management programmes focus upon the conservation of littoral habitat complexity and habitat heterogeneity. The biological effects of shoreline development may be assessed efficiently by combining an assessment of the morphological status of lakeshores and information on macroinvertebrate indicator species with a defined response to the loss of their preferred habitats.