Effectiveness of Road Mitigation for Common Toads (Bufo bufo) in the Netherlands

Roads and traffic may have major impacts on amphibian populations, primarily as a result of amphibian road mortality. A variety of measures have been developed to prevent road mortality of amphibians, such as the construction of fences to keep the animals off the road and amphibian tunnels to provide them a safe passage. We carried out a capture-mark-recapture study to evaluate the performance of two tunnels and permanent drift fences for common toads at a local road in the Netherlands. We found that of the marked toads only 31% used the tunnels to cross the road. We assessed four possible explanations for the fact that a proportion of the toads did not use the tunnels: for toad groups that used the tunnels, as compared to toad groups that did not use the tunnels, (1) the mean distance between the location of first capture and the nearest tunnel was significantly smaller; (2) the mean movement distance along the fence was significantly larger; (3) the number of toad groups that walked in the wrong direction after encountering the drift fence was lower; (4) the mean number of nights between first and last capture of the toad group was significantly higher. Over all study years 28% of the migrating toads—marked and unmarked—that attempted to cross the road ended up on the road pavement, despite the mitigation. Migrating population numbers decreased with about 75% after the mitigation measures were installed. We emphasize that better baseline studies on where toads cross before mitigation and improved knowledge on effects of tunnel design and the distances the animals move along a drift fence are vital to mitigate road impacts properly and maintain viable toad populations. We recommend to base tunnel densities on the mean movement distance of the toads that move only small distances and spent relatively little time along the drift fence, install drift fences that go well beyond the location where toads cross the road, take appropriate measures at entrance roads and at fence ends and consider alternatives to tunnels and fences, such as the creation of breeding waters on both sides of the road

Helpdesk Bijenlandschap : bijenlandschapsadviezen van berm tot tuin en van dak tot stoep

Sinds 2014 geeft de Helpdesk Groene Cirkels al adviezen op maat in de provincie Zuid-Holland. In 2017 is hier de landelijke Helpdesk Kennisimpuls Bestuivers aan toegevoegd. Gezamenlijk hebben zij al tachtig adviezen uitgebracht, onder andere aan een ecologisch hovenier, agrariër, waterschap, installatiebedrijf, bioscoopeigenaar, bollenpolder, natuurspeeltuin en vele andere partijen. Het nieuwe boekje 'Helpdesk Bijenlandschap' geeft een weerslag van deze adviezen

Zijn er nog ondergedoken waterplanten in de Molenpolder bij Tienhoven? : Onderzoek naar de vitaliteit van de zaadbank in waterbodems van de Molenpolder bij Tienhoven in de provincie Utrecht

The water quality and ecological value in the Molenpolder has deteriorated sharply in recent years from clear water with a well-developed underwater vegetation to turbid water where submerged aquatic plants are completely lacking. The fish stock has also changed from a limnophilic fishing community to an eurytope fishing community. During the same period, red swamp crayfish (Procambarus clarkii) has increased in numbers. Although no causal research has been conducted between the increase in crayfish numbers and the decline of the aquatic ecosystem in the Molenpolder, the ecological profile of this crayfish indicates that that it very likely plays a role in maintaining the poor state of the ecosystem. To investigate whether the characteristic underwater vegetation of the Molenpolder can easily recover, the province of Utrecht has asked Wageningen Environmental Research to investigate the vitality of the seed bank in the sediments of the Molenpolder

Second opinion op ‘Compensatieplan Bloemendalerpolder te Weesp en Muiden’ : Specifiek met het oog op beschermde heikikkers en rugstreeppadden

specifiek met het oog op beschermde heikikkers en rugstreeppadde

Modderkruipers en bittervoorn in Pompveld en Andelsch Broek : Visstandbemonstering van grote modderkruiper, kleine modderkruiper en bittervoorn in Natura 2000-deelgebied Pompveld en Andelsch Broek in relatie tot beleidsdoelstellingen en inrichtingsmaatregelen

Nature2000 site Pompveld is part of Nature2000 site Loevestein, Pompveld and Kornsche Boezem and is designated for the weatherfish, spined loach and bitterling. The last two species have a conservation objective, while the weatherfish has an expansion objective. From 2016 to 2020, the current Natura2000 site of the Pompveld was optimized and the design measures in Andelsch Broek was realized. The main goal was the optimization and development of the hydrological system and habitat for the target species. In order to be able to make good statements about the success of these measures, Brabants Landschap considers it of great importance to have a good baseline measurement of these target species for which an expansion and or conservation objective has been set

Solutions to the Impacts of Roads and Other Barriers on Fish and Fish Habitat

As with all wildlife, fish need to move throughout their range in order to complete their life cycles. Unlike other animals, fish cannot leave the stream or river that they are living in or migrating through to bypass a barrier. Structures under roads that facilitate the flow of water, particularly during flood events, are critical to protect the infrastructure and if well designed can provide passage for fish and other aquatic species. However, improper design, construction or maintenance of road-stream crossings can limit or completely prevent fish passage. In addition, roads and traffic can also impact fish and fish habitat by degrading the quality of the streambed, adjacent riparian habitat and water quality, as well as changing patterns in the flow of ground and surface water. 1 Roads and the vehicles that travel on them can negatively affect fish habitat and water quality. 2 Roads and other in-stream structures can be barriers to the movement of fish. 3 Well-informed planning and design of roads can limit the impacts of roads on fish and fish habitat. 4 The most effective road-stream crossings for fish, when long-span 'floodplain' bridges are not an option, are culverts or shorter-span bridges that simulate the natural channel. 5 Specialty culverts and other technical solutions are possible but require careful design and do not provide all the qualities of uninterrupted natural waterways. Roads, railways and other linear infrastructure inevitably intersect waterways, often restricting the movement of fish. New infrastructure should avoid waterways where possible and any crossings that are needed should be designed to allow the natural flow and function of the waterway. Existing road crossings that are barriers to the movement of fish should also be modified to be more natural and improve connectivity for fish. Better designed road-stream crossings also have the added benefit of accommodating flood events and ensuring static infrastructure is stronger and less prone to failure, thereby requiring less maintenance and repair and saving money.</p

Afkreeften in openwatersystemen : Onderzoek naar beheersvisserij van invasieve rivierkreeften in Dordtse wateren

As a result of the incorporation of invasive freshwater crayfish onto the European regulation on Invasive Alien Species, this group of animals has drawn the attention of water managers. Commercial fishery has been suggested as a measure to control or eradicate populations of alien crayfish. However, it is not clear how and where the commercial practices of the fisherman and the needs of water managers converge. This field study provides answers to some of the basic questions regarding the efficiency of different traps, the impact of fishing on the population and the so-called unintended by-catches

Parkeren wij de natuur bij Speelpark Oud Valkeveen? : Second opinion naar beschermde natuurwaarden en in het bijzonder de das (Meles meles)

The municipality of Gooise Meren has drawn up a design zoning plan for the play park Oud Valkeveen. The play park attracts many visitors with cars and buses. The play park is surrounded by Natura-2000 site Eemmeer and Gooimeer Zuidoever and Nature Network the Netherlands and is located on the Gooikust. Foundation De Limiten en Valkeveen and foundation van Vrienden van ‘t Gooi have asked Wageningen Environmental Research to conduct a second opinion on previously published ecological reports regarding the Oud Valkeveen zoning plan of the municipality of Gooise Meren