Food webs in groundwater ecosystems are dominated by only a few top-level consumers, mainly crustaceans. These obligate groundwater dwellers-or stygobites-clearly interact with groundwater biofilm, but it is uncertain whether they affect the abundance and structure of biofilm assemblages. We hypothesized that crustacean stygobites would reduce bacteria and protozoan abundance and alter biofilm assemblage structure. We also hypothesized that high densities of stygobites would remove more bacteria and protozoa than would low densities, and that this difference would become more pronounced over time. First, we established that the amphipods Niphargus fontanus and Niphargus kochianus both ingest biofilm by examining their gut contents. We then conducted two microcosm experiments. The first experiment showed that both N. fontanus and the isopod Proasellus cavaticus increased protozoan abundance but that bacterial abundance was only slightly reduced in the presence of P. cavaticus. In the second experiment, we determined how zero, low, and high densities of N. kochianus affected the biofilm. The high-density treatment of N. kochianus had significantly higher protozoan abundance than the control and the low-density treatment, and high densities of N. kochianus significantly increased the relative proportions of small and medium-sized bacteria over time compared with controls. Our controlled microcosm experiments demonstrate that macroinvertebrate stygobites can influence groundwater biofilm assemblages, although the exact mechanisms are not clear. These results support the hypothesis that stygobites influence essential ecosystem services supplied by groundwater ecosystems.

The Chalk is an important water supply aquifer, yet ecosystems within it remain poorly understood. Boreholes (198) in seven areas of England (UK) were sampled to determine the importance of the Chalk aquifer as a habitat, and to improve understanding of how species are distributed. Stygobitic macro-invertebrates were remarkably common, and were recorded in 67 % of boreholes in unconcealed Chalk, although they were not recorded in Chalk that is concealed by low-permeability strata and thus likely to be confined. Most species were found in shallow boreholes (<21 m) and boreholes with deep (>50 m) water tables, indicating that the habitat is vertically extensive. Stygobites were present in more boreholes in southern England than northern England (77 % compared to 38 %). Only two species were found in northern England compared to six in southern England, but overall seven of the eight stygobitic macroinvertebrate species found in England were detected in the Chalk. Two species are common in southern England, but absent from northern England despite the presence of a continuous habitat prior to the Devensian glaciation. This suggests that either they did not survive glaciations in the north where glaciers were more extensive, or dispersal rates are slow and they have never colonised northern England. Subsurface ecosystems comprising aquatic macro-invertebrates and meiofauna, as well as the microbial organisms they interact with, are likely to be widespread in the Chalk aquifer. They represent an important contribution to biodiversity, and may influence biogeochemical cycles and provide other ecosystem services.

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Groundwater ecosystems comprising micro-organisms and metazoans provide an important contribution to global biodiversity. Their complexity depends on geology, which determines the physical habitat available, and the chemical conditions within it. Despite this, methods of classifying groundwater habitats using geological data are not well established, and researchers have called for higher resolution habitat frameworks. A novel habitat typology for England and Wales (UK) is proposed, which distinguishes 11 geological habitats (geohabitats) on hydrogeological principles and maps their distribution. Hydrogeological and hydrochemical data are used to determine the characteristics of each geo-habitat, and demonstrate their differences. Using these abiotic parameters, a new method to determine abiotic habitat quality is then developed. The geo-habitats had significantly different characteristics validating the classification system. Karstic and porous habitats were generally of higher quality than fractured habitats. All geo-habitats were highly heterogeneous, containing both high quality habitat patches that are likely to be suitable for fauna, and areas of low quality that may limit faunal distributions. Overall, 70 % of England and Wales are covered by lower quality fractured habitats, with only 13 % covered by higher quality habitats. The main areas of high quality habitats occur in central England as northsouth trending belts, possibly facilitating dispersal along this axis. They are separated by low quality geo-habitats that may prevent east-west dispersal of fauna. In south-west England and in Wales suitable geo-habitats occur as small isolated patches. Overall, this paper provides a new national-scale typology that is adaptable for studies in other geographic areas. Weitowitz et al., 2017. Hydrogeology Journal

New housing development can result in impacts on nearby protected nature conservation sites, even if development is outside the site boundary. High levels of housing may be associated with adverse impacts on ecological features in protected sites from increased recreation pressure. However, few studies have investigated the spatial link between housing and visitor numbers. An understanding of the impact of housing on visitor use, especially the distances at which housing relates to recreation levels and the importance of other factors (e.g. parking provision) is essential to inform the assessment of new housing and is relevant to strategic planning of development within the UK. We use a long-term visitor dataset (2003–8) to disentangle the housing–visitor association at foot-only and parking locations on important nature conservation sites. We conclude with negative binomial regressions that model the effect of housing on visitor numbers, while controlling for habitat, parking provision and season. Our results demonstrate that more housing consistently means more visitors to protected sites, across most habitats. This is particularly the case for on-foot visitors that originate from housing within 1.5 km, highlighting that additional housing development in proximity to protected sites is likely to significantly increase recreation pressure. For visitor numbers at parking locations, levels of housing within 15 km of protected sites were also a significant predictor, but depended on habitat type. These results demonstrate that housing allocations closer to protected sites are likely to have a greater impact in terms of visitor numbers and may help underpin future assessments of strategic plans.