Volume One 8. Indigenous Biodiversity vegetation clearance is also necessary to assist in minimising the loss of ecosystems, habitats and areas with indigenous biodiversity value. It is important to note that there may be some circumstances where the clearance of indigenous vegetation will be excluded from rules, such as that which occurs under plantation forestry or on existing roads. The policy will also contribute to achieving outcomes for the protection of outstanding natural features and landscapes and the maintenance of high amenity areas (see Chapter 7 - Landscape, Volume 1 of the MEP). Policy 8.3.4 – Improve the management of drainage channel maintenance activities to mitigate the adverse effects from these activities on the habitats of indigenous freshwater species. The Council operates and maintains a historic network of drainage channels on the Wairau Plain. This network reduces groundwater levels and improves the productive potential of the rural land resource. Some of the drainage channels are modified rivers, while others are artificial watercourses. The drainage channels often provide habitat to indigenous freshwater fauna, including eel (tuna) and other freshwater fish and kōura. These species are a source of mahinga kai to Marlborough’s tangata whenua iwi and contribute to Marlborough’s overall biodiversity. The maintenance of the drainage network involves the control and/or removal of aquatic plants, wetland plants and accumulated sediment from the bed of the channels that would otherwise reduce the efficiency of water flow and increase water levels. Such maintenance can adversely affect aquatic animals within the channel, either through direct removal or a reduction of habitat. While it is difficult to completely avoid the adverse effects of drainage channel maintenance on aquatic biodiversity, it is possible, using good environmental practice guidelines, to mitigate the nature and degree of effect from maintenance activities. Policy 8.3.5 – In the context of Policy 8.3.1 and Policy 8.3.2, adverse effects to be avoided or otherwise remedied or mitigated may include: (a) fragmentation of or a reduction in the size and extent of indigenous ecosystems and habitats; (b) fragmentation or disruption of connections or buffer zones between and around ecosystems or habitats; (c) changes that result in increased threats from pests (both plant and animal) on indigenous biodiversity and ecosystems; (d) the loss of a rare or threatened species or its habitat; (e) loss or degradation of wetlands, dune systems or coastal forests; (f) loss of mauri or taonga species; (g) impacts on habitats important as breeding, nursery or feeding areas, including for birds; (h) impacts on habitats for fish spawning or the obstruction of the migration of fish species; (i) impacts on any marine mammal sanctuary, marine mammal migration route or breeding, feeding or haul out area; (j) a reduction in the abundance or natural diversity of indigenous vegetation and habitats of indigenous fauna; (k) loss of ecosystem services; (l) effects that contribute to a cumulative loss or degradation of habitats and ecosystems; (m) loss of or damage to ecological mosaics, sequences, processes or integrity; (n) effects on the functioning of estuaries, coastal wetlands and their margins; (o) downstream effects on significant wetlands, rivers, streams and lakes from hydrological changes higher up the catchment; 8 – 11