Rangitāiki River Estuary National Objectives Framework (NOF)
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Water quality and ecology of the Rangitāiki Water Management Area Rangitāiki River Estuary National Objectives Issues: Nutrients can promote excess plant and algae growth. We measure plant and algae growth by Framework (NOF) Increasing nutrients measuring the concentrations of chlorophyll-a, the The National Policy Statement includes a National Objectives Framework pigment in plants that is used for photosynthesis. (NOF), which sets compulsory national values for freshwater to protect Nuisance biological growths The Rangitāiki estuary has the highest maximum ‘human health for recreation’ and ‘ecosystem health’. chlorophyll-a concentrations and the second highest Whitebait habitat median of the Bay of Plenty river estuaries. The NOF has a series of ‘bands’ ranging from A to D, and National Bottom Lines for the following attributes in rivers: River estuaries are dynamic environments with Chlorophyll-a To protect ecosystem health: Nitrate, Ammonia 16 large changes in tidal and river flows. About 63 Median To protect human health for recreation: E.coli, Cyanobacteria percent of native freshwater fish species use 14 estuaries to swim between fresh and salt water. 25%-75% 12 Like many river estuaries, the Rangitāiki has little Min-Max aquatic vegetation or macro-algae. 10 Freshwater usually dominates the water quality 8 NOF Banding of river estuaries. Flood flows and the delivery of 6 sediment and nutrients into estuaries can make it 4 Nitrate hard for plants and animals to live and grow there. Phosphorus and nitrogen are increasing in the 2 estuary. Nitrogen is also increasing in the whole 0 Ammonia catchment, while phosphorus is only increasing in -2 the lower catchment. Point sources and land use Tarawera Rangitāiki Whakatāne Kaituna Ōpōtiki Ōpōtiki Secondary contact River River River River Estuary @ Estuary @ influence phosphorus in the lower catchment. Estuary Estuary Estuary Estuary Kukumoa Wharf (wading/boating) Primary contact (Swimming) Good A How does Lakes Aniwhenua B the Rangitāiki catchment and Matahina C >MAS stack up? Poor D Issues: Annual Median (2014) for nitrate, ammonia Choking exotic lake weed growth and secondary contact (wading/boating). 95th Percentile for primary contact. Values Excess nutrients impacting algae, are greater than the minimum acceptable weed growth and ecology state for primary contact only. Impacts of weed growth on recreational and aesthetics MCI Class Excellent We described the health of lakes using the trophic Lake Submerged Plant Indicator Results 2014 Good level index (TLI), calculated using total nitrogen, LakeSPI Native total phosphorous, water clarity and chlorophyll-a. Lake Condition Condition Invasive Impact % Fair % % Poor TLI results show both lakes are nutrient-enriched, Lake Aniwhenua 12% 8% 85% and that Lake Aniwhenua is classed as eutrophic (poor water quality) and Matahina is classed as Lake Matahina 10% 3% 96% supertrophic (very poor quality). Suitability for Lake macrophytes and aquatic plants are important Trophic Level Index Recreation Grade habitats for fish and invertebrates and play an 6 Good key role in nutrient cycling. Macrophytes are 5.5 monitored and used to generate Lake Submerged Supertrophic 5 Fair Plant Indicators (LakeSPI) to classify the ecological Land use condition of the lakes. 4.5 Eutrophic 4 Urban Introduced macrophytes TLI Units 3.5 or aquatic weed have Exotic Forest Mesotrophic largely out-competed native How should 3 species in these two lakes. Indigenous Forest these lakes 2.5 See what their LakeSPI be managed? Oligotrophic Horticulture state is in the graph (right). 2 12/13 01/14 02/14 03/14 04/14 Pasture Aniwhenua Matahina Coastal and Macro-invertebrates Nutrients freshwater We use invertebrates to assess stream health as Excess nutrients can cause increased growth of aquatic they integrate a wide range of environmental plants and algae. Excessive growth of these organisms recreation factors over relatively long periods of time. can clog water intakes, use up dissolved oxygen as they decompose and block light to deeper waters. Streams mostly support invertebrate communities monitoring typical of streams in good or excellent health. Lake and reservoir eutrophication can occur, which Streams draining from native bush and exotic forest produces unsightly scums of algae on the water surface When contaminated by human or animal had the highest health, while the health in streams and leads to descreased animal and plant diversity and faeces, water can contain disease-causing draining from pasture was the lowest. affects recreational water use. bacteria, viruses, and protozoa (such as Stream health was especially low in salmonella, campylobacter or giardia). the Rangitāiki River’s main stem, What Where These organisms can pose a health risk on the plains. Other sites, Macroinvertebrate are the in waters used for recreational activities particularly in the lower Rangitāiki, Community Index nitrogen and such as swimming. had invertebrate communities (MCI) class is most phosphorous indicative of fair or poor health. abundant in hot spots? the Rangitāiki Where catchment? Average Annual Average Annual Total TOx-N would you Total Phosphorus Load Total Nitrogen Load (kg/ha/y) choose (2013) (2013) to swim? Phosphorus load Otamatea Otamatea Avg. Flow Rangitāiki Rangitāiki 1.00 @ SH5 @ SH5 Bridge Bridge Whirinaki Whirinaki @ Galatea @ Galatea 0.10 Bridge Bridge * Rangitāiki Rangitāiki Invertebrates were collected from the streambed by disturbing the @ Murupara @ Murupara Bridge Bridge substrate immediately above a triangular net, which captured all 0.01 * dislodged material (both invertebrates and organic matter). Rangitāiki Rangitāiki @ Te Teko @ Te Teko 0 50 100 150 200 0 1000 2000 3000 Nature Pasture Pine kg/day (m3/s) kg/day Land Cover See more at: www.boprc.govt.nz/environment/water/swimming-water-quality/ BAY OF PLENTY REGIONAL COUNCIL TOI MOANA Rangitāiki.