Consequences of fish for cladoceran, water beetle and macrophyte communities in a farmland pond landscape: implications for conservation

ParisV. Stefanoudis, CarlD. Sayer, HelenM. Greaves, ThomasA. Davidson, Hannah Robson, David Almeida, Elizabeth Smith
2017 Fundamental and Applied Limnology  
49 Traditionally, fish have been neglected in pond ecology and conservation 50 studies although it has been often been assumed that they have a detrimental 51 impact on pond biodiversity and ecosystem function. In order to assess the 52 consequences of fish for pond biodiversity and ecosystem structure we 53 sampled a set of 40 small farmland ponds (20 with and 20 without fish) in 54 eastern England and compared their water chemistry as well as the 55 assemblage characteristics (abundance,
more » ... cs (abundance, diversity, species composition) of 56 three biological groups: cladocerans (zooplankton), water beetles and 57 macrophytes. Water depth was significantly greater in fish ponds, while pond 58 bottom oxygen levels and pH were significantly higher in the ponds without 59 fish. The presence of fish significantly reduced the abundance of macrophytes 60 and altered the community composition of cladocerans and macrophytes, but 61 had no detectable influence on water beetles. Variation partitioning using 62 environmental and spatial variables, indicated all three biological groups were 63 spatially structured. The inclusion of fish however, reduced the importance 64 attributed to space in the case of both cladocerans and macrophytes, 65 suggesting that space effects for these two groups were at least partly the 66 result of a spatially structured predator (i.e. fish) and not because of dispersal 67 limitation or mass effects. In most cases fish did not have an effect on 68 cladoceran and water beetle alpha diversity (number of species, Shannon's 69 and Simpson's index), although the opposite was true for macrophytes. 70 Nevertheless, at the landscape level, gamma diversity (i.e. total number of 71 species) was enhanced for all three biological groups. Our results suggest 72 that fish, at least small pond-associated species, are an important component 73 of heterogeneity in farmland pond networks, thereby increasing landscape-74 scale diversity of several faunal and floral elements. Consequently, we 75 propose that fish should be more fully included in future pond biodiversity 76 surveys and conservation strategies. 77 78 79 water beetles. 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97
doi:10.1127/fal/2017/1004 fatcat:7l4ywnj62vd3bn7ikahwsfzaw4