BEFORE THE SPECIAL TRIBUNAL FOR THE NGARURORO AND CLIVE RIVERS WATER CONSERVATION ORDER
AT NAPIER
IN THE MATTER of the Resource Management Act 1991 (the Act)
IN THE MATTER of a Special Tribunal appointed under s202 of the Act to consider an application for a Water Conservation Order made by New Zealand Fish and Game Council, the Hawke’s Bay Fish and Game Council, Ngāti Hori ki Kohupatiki, Whitewater New Zealand, Jet Boating New Zealand, and the Royal Forest and Bird Protection Society of New Zealand (the Applicants) in relation to the Water Conservation Order
The Special Tribunal Richard Fowler QC (Chair) Alec Neill Dr Roger Maaka Dr Ngaire Phillips John McCliskie
STATEMENT OF EVIDENCE OF DR VAUGHAN FRANCIS KEESING (ECOLOGY) ON BEHALF OF HORTICULTURE NEW ZEALAND
25 January 2019
Helen Atkins/Nicole Buxeda PO Box 1585 Shortland Street AUCKLAND 1140
Solicitor on the record Helen Atkins [email protected] (09) 304 0421 Contact solicitor Nicole Buxeda [email protected] (09) 304 0429
CONTENTS
INTRODUCTION...... 3 EXECUTIVE SUMMARY ...... 3 QUALIFICATIONS AND EXPERIENCE ...... 4 BACKGROUND AND ROLE ...... 6 SCOPE OF EVIDENCE ...... 6 DETERMINING OUSTANDING ...... 6 Assessment of Outstanding ...... 6 The data ...... 8 THE RESULTS ...... 9 Natural State ...... 9 Aquatic characteristics compared nationally...... 9 Water Quality ...... 10 Aquatic Macroinvertebrates ...... 14 Fish diversity ...... 14 Avian fauna ...... 16 SUMMARY ...... 18 THE EVIDENCE OF OTHERS ...... 19 Water quality ...... 19 CONCLUSION ...... 25
ATTACHMENTS
Attachment 1: “Aquatic ecology of the lower Ngaruroro River: ecological assessment and comparison at a local, regional and national scale.” Boffa Miskell Limited (BML Report), 20 February 2018 Attachment 2: NIWA map of Torrent fish distribution
Attachment 3: Scoring table from Hughey et al 2012 – labelled “Significance assessment calculations for native fish life in the Hawke’s Bay”
2 INTRODUCTION
1. My name is Vaughan Francis Keesing.
2. I am a Senior Ecologist and Partner with the consulting firm of Boffa Miskell Limited, Wellington.
3. My evidence is given in relation to the application for a water conservation order (WCO) on the Lower Ngaruroro River, Hawkes Bay, for Horticulture NZ.
EXECUTIVE SUMMARY
4. The lower Ngaruroro River is significant and valuable as aquatic habitat but it is not “outstanding” at a national scale.
5. This conclusion is from an understanding that “outstanding” is a rigorous test using a national ranking comparison, at least in terms of measurable biotic attributes.
6. The lower river has values despite the high level of modification. It maintains good water quality (as a general statement) and is a significant natural area. Its aquatic biotic characteristics do not rank it amongst the top 10% of National large rivers. The seasonal population level of black fronted dotterel may be the exception.
7. The threatened black fronted dotterel has a potential population in the lower river that, under the threshold adopted, could be considered “outstanding” on a national scale (i.e. at any one time, the reach supports 5 % or more of the national population of this species). That said the population data is old and my assessment is based on estimates towards the lower end of various survey data. More recently the dotterel’s national total population numbers appear to have stabilised towards the higher end of the survey range reported. If so the lower Ngaruroro River will not harbour 5 or more % of the total NZ population (the threshold) and therefore would not be outstanding for that characteristic.
8. The lower river has low levels of nutrients as compared with the lowland portions of nine other large Hawke’s Bay rivers. There are issues with dissolved oxygen, water clarity, and E. coli levels. The water quality in the lower Ngaruroro River does not to rank within the top 10% of rivers when compared against the lowland sections of 16 national rivers.
9. The aquatic macroinvertebrate fauna of the lower Ngaruroro River, when compared against 16 national lowland rivers, ranked eighth equal for mean and median values. This suggests, whilst the MCI score is suggestive of good water quality, it is well outside of
3 the top 10% of national lowland rivers, and, therefore, also all national large rivers.
10. The fish community of the lower Ngaruroro River is regionally important as it has the highest taxa richness, including the highest number of native taxa, and it has the highest number of threatened or at risk taxa of the nine other major Hawke’s Bay rivers. At a national scale, native taxa richness places the lower Ngaruroro in the top 10% of a set of national lowland rivers (5th of 17 I tested). When a wider set of rivers nationally are compared (as I believe the “outstanding” test requires) the Ngaruroro ranks 31st which is just outside of the 10% threshold. When the comparison is weighted for at risk and threatened taxa it ranked 54th (of 303) and in that scenario is outside of the top 10% (it is in the top 18%).
QUALIFICATIONS AND EXPERIENCE
11. I hold the qualifications of Doctor of Philosophy (PhD) in Ecology, BSc (Hons 1st class) in Zoology, and a Diploma in Research Statistics.
12. My skills lie in ecology. I have specialist skills in the areas of limnology (freshwater ecology), entomology (invertebrate ecology), and botany. The majority of my work over the last 20 years has been aquatic in nature.
13. After a Post-Doctoral research fellowship at Lincoln University, I began practising as a consulting ecologist and have done so for the last 21 years. I have worked in a variety of locations across New Zealand including the West Coast, Canterbury, Central North Island, Lower North Island, the Far North, Auckland Region and the Bay of Plenty.
14. During my time as a consultant ecologist I have been engaged in many small to very large projects and have undertaken assessments and work that has led to the preparation and delivery of over 40 briefs of evidence, 20 of those at the Environment Court and three for Boards of Inquiry.
15. This work has included significance and ecological values assessments of many systems and habitat types. Relevant to the evidence I present today in terms of experience are:
(a) Assessments of regionally significant rivers and the effects of roads (for: Transmission Gully, Northern Gateway, Mackays to Peka Peka);
4 (b) Assessments of rivers affected by damming and irrigation storage (for: Wairau hydro-electric power scheme, Waitaki hydro-electric power scheme, Coleridge Hydro- electric power scheme, Arnold hydro-electric power scheme, Hurunui irrigation project, Waitohi irrigation dams);
(c) Assessments of habitat (aquatic and wetland) requirements and quality and value related to water conservation orders (i.e. the Hurunui River WCO, and the Rakaia WCO (proposed variation)).
(d) Waikanae River recharge programme, Kapiti District. Four years of monthly summer period monitoring of water quality, periphyton, fish and aquatic macroinvertebrates to characterise natural variation in the Waikanae River.
(e) Natural Character assessment of the Kapiti District Coast. Assessment of biophysical attributes as a component of a natural character assessment.
(f) In determining values and significance I have also undertaken projects that have required specific values assessments, and these include:
i. Determining significant wetlands of the West Coast Region; Ashburton SNA process, Rangitahi Protected Natural Areas survey, significance assessments in over 150 Franklin District Conservation lots, 50 Western Bay of Plenty lots.
ii. Over 20 subdivisions (e.g. Omaha South (Darby Partners), Long Bay (Landco) Pegasus Bay (Infinity Co)), and a number of plan changes (e.g. Porters Ski field expansion),
16. Most of my work over the last 20 years has been in rivers, streams and wetlands sampling fish, macroinvertebrates, periphyton, and water quality to assess ecological value, significance, effects, and the development of remediation, and mitigation or offset programmes.
17. I confirm that I have read the ‘Code of Conduct' for expert witnesses contained in the Environment Court Practice Note 2014. My evidence has been prepared in compliance with that Code. In particular, unless I state otherwise, this evidence is within my sphere of expertise and I have not omitted to consider material facts known to me that might alter or detract from the opinions I express.
5 BACKGROUND AND ROLE
18. I have been asked to prepare evidence based on my (and my colleagues) research, assessment, and report for Horticulture NZ (HortNZ) (undertaken in 2017) on the aquatic condition and values in the lower Ngaruroro River with specific analysis on the “outstandingness” of biological and water quality attributes as they rank against national comparisons.
19. I have not otherwise been involved in the TANK or any other aspect of the issues in the local catchment in terms of use and protection of the Ngaruroro River.
SCOPE OF EVIDENCE
20. This evidence is placed before the Tribunal to assist in matters of technical aquatic ecological characteristics as they pertain to a measure of “outstanding” of those attributes in the lower Ngaruroro River.
21. This evidence summarises a report my colleagues and I prepared for HortNZ based on analysis of a range of biological characteristics of the aquatic biology and water quality of the lower Ngaruroro River (from the cableway to the tidal influence) and how these attributes ranked on a national basis, as a measure of the outstanding. A copy of this report is attached to this evidence as Attachment 1.
22. I then address the applicants’ evidence in regard to the same or similar attributes and the rankings they have given them, and where differences occur make comment on the potential reasons for those differences.
DETERMINING OUSTANDING
Assessment of Outstanding
23. In assessing outstanding I followed previous Environment Court and hearing panel decisions and discussions, as they have reasonably defined or illuminated what is meant in a WCO context of “outstanding”.
24. In the Kawarau River WCO application (amendments) Judge Jackson wrote: “in part 9 of the RMA the planning tribunal wrote: the test as to what is outstanding is a reasonably rigorous one, …to qualify as outstanding a characteristic would need to be quite out of the ordinary on a national basis”…
6 25. However, this is not further defined or refined as to what “quite out of the ordinary” means in a comparative context.
26. This approach was also adopted in the Hurunui application where they said:
“The word “outstanding” in section 199 RMA was considered in the Rangitata decision. In [17] the Court referred to earlier decisions in which it had been held that the test as to what is outstanding is a reasonably rigorous one and that to qualify as outstanding a characteristic would need to be quite out of the ordinary on a national basis. The Court in Rangitata accepted a submission that; …. The amenities should stand out on a national comparative basis. If one takes a national comparative approach the fact a wider region is well endowed with similar high quality features, may well suggest the particular waters do not stand out when considered in a national context.
We have adopted this approach and also that even if a characteristic is familiar to people in an area it may still be “outstanding” when viewed from a national perspective.”
27. I note that the threat status or risk to the water body has not been a determining factor in making a WCO (Rangitata Report, second Gowan Tribunal and Kawarau decision) - only the presence of characteristics which are “outstanding”, but that an application should still recognise any threats to the outstanding characteristics.
28. It has been stated that the purpose of water conservation orders is to provide recognition of the outstanding amenity or intrinsic values of water bodies and that a water conservation order may provide for any of the following (section 199(2)):
the preservation as far as possible in its natural state of any water body that is considered to be outstanding the protection of characteristics which any water body has or contributes to, and which are considered to be outstanding,- o as a habitat for terrestrial or aquatic organisms: o as a fishery: o for its wild, scenic, or other natural characteristics: o for scientific and ecological values: o for recreational, historical, spiritual, or cultural purposes: the protection of characteristics which any water body has or contributes to, and which are considered to be of outstanding significance in accordance with tikanga Māori.
29. As stated above the assessment of outstanding for an avian species was determined by recognition of use of the habitat by at least 5% of the national population of a species. I follow this threshold here.
7 30. There are less clear approaches for other ecological components (habitat condition, native fish taxa richness, water quality, or quality of the macroinvertebrate communities) and previous decisions do not articulate what “quite out of the ordinary on a national basis” means.
31. I adopted the following thresholds:
(a) For water quality – the top 10% of the compared National similar sized rivers.
(b) For Fish taxa richness, the top 10% of the compared National similar sized rivers.
(c) For macroinvertebrates a MCI > 120 is the preferred approach (to represent “out of the ordinary” – but analysis showed no mean MCI value for any river used here was over 120 (the threshold for “excellent”) and so I lowered this threshold to MCI > 100 (“Good”) - and then considered the top 10% ranking of the tested rivers.
The data
32. The ecological condition (and values) of the lower Ngaruroro River was assessed in three ways:
(a) the ecology (water quality, macroinvertebrate, fish, and avifauna) of the lower river was determined along a downstream gradient;
(b) the overall ecological condition was compared against nine other rivers within the Hawke’s Bay region;
(c) the overall ecological condition was compared against 16 other similar (lowland) rivers on a national scale.
33. To allow for my assessment and comparison to be made, water quality, macroinvertebrate, fish, and avifauna data were collected from a range of sources (largely NIWA and HBRC databases, as well as LAWA1). These data were processed and filtered to eliminate erroneous data (data whose credibility or relevance could not be assured), and to remove data points with outlier values. Analyses included calculating descriptive statistics and depicting these via box plots (thus incorporating many years of data). These results then allowed for ranking of each parameter according to mean and median values to determine how each
1 Land and Water Aotearoa
8 parameter compared on a local, regional, and national scale. I initially used data from 16 other similar sized rivers in their lower reaches. For some datasets where ranking was near the 10% threshold (fish in particular) I expanded the comparison to over 300 other large rivers using entire catchment records.
34. Detailed methodologies used for water quality, macroinvertebrates, fish, and avifauna are in the report entitled “Aquatic ecology of the lower Ngaruroro River: ecological assessment and comparison at a local, regional and national scale.” Boffa Miskell Limited (BML Report), 20 February 2018 (Attachment 1).
THE RESULTS
Natural State
35. Section 199(1)(a) and (2)(a) of the RMA pertains to recognising and sustaining waters in their “natural state”. The Court in Rangitata held in [20] that “Natural state means towards the pristine end of the artificial/polluted to pristine continuum”. The physical habitat of a braided river in a natural state can be predicted with reasonable certainty.
36. The lower Ngaruroro is not in or near its natural state (for further discussion I refer to Appendix 2 from the BML Report).
Aquatic characteristics compared nationally.
37. I compared the lower Ngaruroro River initially to 16 other similar sized lower river data sets, and then to a wider national river (of similar catchment size) set of data. The 16 low land similar scaled rivers were:
1. Rakaia River 2. Waiau River 3. Clutha River 4. Ashley River 5. Waitaki River 6. Mataura River 7. Waimakariri River 8. Grey River 9. Wairau River 10. Ruamahanga River 11. Rangitaiki River 12. Rangitikei River 13. Manawatu River 14. Whakatane River
9 15. Kaituna River 16. Mokau River
38. To allow for fair comparison only lowland parts of the rivers were selected for the first comparison because:
(a) There were no obvious barriers such as dams or concrete lined channels;
(b) Surrounding land has been modified to a similar degree as the Heretaunga Plains;
(c) Monitoring locations were upstream of the salt wedge.
39. Nine South Island rivers and eight North Island rivers (including Ngaruroro River) were selected to ensure different geographical regions were represented (the list above).
40. For consistency, data were collected as per the methodologies used to measure the Ngaruroro. In the following I present only the graphs that summarise the analysis as the most expedient way of illustrating my findings.
Water Quality
41. The water quality parameters for which there were sufficient data for a comparison were: dissolved oxygen, water clarity, turbidity, nutrients (DRP, Nitrate, Ammoniacal nitrogen), pH, and E. coli.
42. A graphical representation of the condition ranked by median value from left to right (left is best) for each are shown below and the Ngaruroro indicated by an orange arrow.
10
11
12
43. The lower Ngaruroro River statistics range from 4th to16th ranked and average around 8th - i.e. middle of the group and not in the top 10%.
13 Aquatic Macroinvertebrates
44. In terms of macroinvertebrate assemblages, the Ngaruroro ranks 8th.
45. EPT taxa richness ranked 9th.
46. While the macroinvertebrate indices show a generally good quality and representative set of assemblages, in terms of comparing the fauna against other rivers, the limited lower river same size scenario (the 16 rivers) illustrates that the Ngaruroro assemblages are typical (middle ranked).
Fish diversity
47. The Ngaruroro River ranks 5th best of the 16 lowland rivers used in the comparison for total richness and threatened/at risk species richness. It ranks second best (equally with three other rivers) for native taxa richness (13 native taxa). This is shown in the table below.
14
taxa
Taxa count
Nativecount
"NUM" in"NUM" FWDB)
Threatened taxa
Threatened/at risk
Abundance (sum of
Waitaki River 18 (1) 15 (1) 10 (1=) 6118
Kaituna River 16 (2=) 12 (6) 6 (7=) 1295
Rakaia River 16 (2=) 13 (2=) 10 (1=) 4176
Waimakariri River 16 (2=) 13 (2=) 9 (3=) 2381
Ngaruroro River 15 (5) 13 (2=) 8 (5) 801
Clutha River 14 (6=) 10 (9=) 5 (12) 2696
Grey River 14 (6=) 13 (2=) 9 (3=) 8140
Ruamahanga River 14 (6=) 11 (7=) 6 (7=) 2119
Waiau River 14 (6=) 11 (7=) 7 (6) 1965
Mokau River 13 (10=) 9 (12=) 4 (13=) 5864
Rangitaiki River 13 (10=) 9 (12=) 4 (13=) 1612
Ashley River 12 (12) 10 (9=) 6 (7=) 859
Manawatu River 12 (12) 9 (12=) 4 (13=) 8276
Mataura River 11 (14) 10 (9=) 6 (7=) 302
Rangitikei River 11 (14) 8 (15=) 3 (17) 1365
Wairau River 10 (16) 8 (15=) 6 (7=) 2661
Whakatane River 9 (17) 7 (17) 4 (13=) 430
Numbers in parenthesis () give the ranking for that attribute
48. Given the importance of rivers as conduits (passage) and because fish life cycles can make use of the “full” extent of a river (fish passage is a character WCO often refer to) I expanded the comparative data set for fish to all rivers of a similar (large) size in NZ where there was adequate data. The comparative set was 303 rivers. This helps clarify the Ngaruroro’s ranked position in New Zealand.
49. That analysis shows that the Buller River has 20 native fish taxa recorded in the NZFFD (New Zealand Freshwater Fish Database) which is the highest richness. Four rivers have records of 19 native
15 fish taxa within their catchments, compared to the Ngaruroro which has 14 native fish taxa present in the full catchment). In total, 30 of the 303 rivers tested have more than 14 native fish taxa recorded in their catchments; therefore, the Ngaruroro (with 14 native taxa in total) ranks 31st= in native fish taxa richness on a national scale (that is just outside of the top 10%).
50. The above analysis does not weight for threatened species. If such a weighting is undertaken then against the 303 rivers included in this analysis, the Ngaruroro catchment ranks 54th = which puts it in the 17.8th percentile.
51. To assess the abundance of the entire threatened species community within the Ngaruroro, I compared the combined abundances of those taxa (7 species2) from the NIWA FWDB for the 16 previously used rivers. For this, the Ngaruroro ranked 13th of 16.
Abundance of threatened taxa using only those treatened taxa found in the Ngaruroro River (NIWA FWDB)
9000 8000 7000 6000 5000
4000 Number 3000 2000 1000 0
Rivers of similar sized catchment
Avian fauna
52. The lower Ngaruroro River has a high diversity of avifauna habitats; however, in general, habitat quality is not high due to the dominance of exotic vegetation, channelization, and frequent
2 Since the new fish threat classification of Dunn et al 2017, redfin bully are no longer threatened. Dunn, N; Allibone, R; Closs, G; Crow, S; David, B; Goodman, J; Griffiths, M; Jack, D; Ling, N; Waters, J; Rolfe, J. 2017. Conservation status of New Zealand freshwater fishes, 2017. Department of Conservation monograph series.
16 bed works (i.e. gravel extraction). 17 Threatened and At Risk avifauna species utilise the lower Ngaruroro River seasonally. The table below lists the species and their population estimates.
Species Ngaruroro National National Nationally River Population Population Outstanding Population Proportion (%) habitat
Australasian bittern 13 500-7504 0.1-0.25 No Black-billed gull 400-600 15000 2.7-4 No Grey duck 30 -1 -1 Unknown White heron At least 1 150-200 - 2 No Black-fronted tern 30-75 5000 0.01 No Banded dotterel 500 25000- 1-2 No 50000 Caspian tern Rarely 3000 -2 No sighted6 Wrybill 1 4500-5500 0.02 No Marsh crake Unspecified 5000-20000 -2 No number New Zealand pipit 247 >100000 -2 No Red-billed gull A few birds8 >100000 -2 No South Island pied 10 90000- 0.008-0.01 No oystercatcher 130000 Spotless crake Unspecified 5000-20000 -2 No number Australasian pied stilt 173-461 30000 0.6-1.5 No New Zealand Unspecified 1700 -2 No dabchick number Black-fronted 39-1459 1700-3000 1.95-7.25 possibly dotterel Black shag 3-18 10000- <0.2 No 20000 Little black shag 0-16 2000-10000 0.2-0.8 No
Table footnotes
1 Due to hybridisation with mallard ducks, there is uncertainty about the national population of grey; consequently, the Ngaruroro River population as a proportion of the national population cannot be calculated.
2 There is uncertainty about the size of the Ngaruroro River population therefore the proportion of the national population cannot be calculated.
3 Likely sighting but unconfirmed.
4 Most likely an underestimate of the national population due to the cryptic nature of the species and difficultly detecting them during surveys.
5 Conservative estimate using the unconfirmed bittern sighting and the likely underestimated national population size.
6 Unspecified number of birds observed.
17 7 Underestimate of Lower Ngaruroro River population as only the Otamauri Stream to Mangatahi section was surveyed.
8 Unspecified number of birds observed.
9 McClellan’s evidence shows the 2018 survey data – 200 BFD
53. One species (the black-fronted dotterel) has an estimated Ngaruroro population that could be outstanding on a national scale (i.e. at any one time, the reach supports 5% or more of the national population of this species). The assessment depends entirely on which numbers for the local and national population estimates are used. If one uses the average number across the 7 periods of data and the latest national estimate (3000) then it is below the 5% threshold. If one uses the 2018 population (200) and either national population estimate it is over.
54. The other 16 Threatened and At Risk species do not reach the 5% threshold; therefore, the lower Ngaruroro River is not considered to be outstanding habitat for these avifauna species.
55. Given the situation with uncertain numbers for the black fronted dotterel I acknowledge the lower Ngaruroro might be outstanding habitat for the black-fronted dotterel under the criteria adopted, but that conclusion depends on the way one chooses to use the numerical estimates of the local and national populations.
SUMMARY
56. At a national scale the Ngaruroro is not in the top 10% of rivers for the attributes of:
water quality native fish species richness number of threatened fish species present abundance of threatened species present macroinvertebrate community statistics, or avian river fauna (as a whole).
57. However, it might meet the threshold for the population of black fronted dotterel seasonally present, depending on the current NZ population estimate.
58. It is also very close to the threshold in terms of native fish species richness.
18 THE EVIDENCE OF OTHERS
59. The evidence of Ms McArthur deals with water quality and indigenous fish of the lower Ngaruroro River for the applicants.
60. The evidence utilises similar, and in some cases the same, data as I do.
61. I concur generally with the values assessments and opinions in terms of the condition of water quality, that there are good macroinvertebrate communities and I agree with the freshwater fish community that is present.
62. I agree also that the lower river, while modified, is a significant natural area, would qualify under criteria as significant, and is appropriately recognised as one of the best rivers (or lower main river portions) in the region.
63. What I do not see in her evidence is an assessment of “outstanding” condition or the criterion / criteria used to test if it is “outstanding”.
64. I see a range of language (some emotive in my opinion) purporting a unique state of character and that being of value or significance is enough to be outstanding.
65. I do not agree that that is the case, as virtually all the main rivers in the Hawke’s Bay, or indeed the country, can be found to be “significant” and all are of ecological value (accepting a gradient of values).
66. My understanding of “outstanding” from my involvement in other WCO’s, natural character assessments, and wider reading, is that “outstanding” is a rigorous higher test than testing against significance or ecological values.
67. With that in mind I offer the following commentary on the substance of Ms McArthur evidence.
Water quality
68. The data presented in Table 1 shows separately the areas of the Ngaruroro River with monitoring data and places those metrics in quarterly categories reflecting national data set divisions. The Ngaruroro in all cases has no “issue” with E. coli, TN, TON, or Ammonia (these measures being within the “best” 25% of the national data set). However, areas of the Ngaruroro are in the worst 25% for DRP, and Turbidity and clarity. It becomes unclear just how to read water, as it is a “mixed bag” of condition. It is fair to say on balance water quality is good, but this is not a test of the
19 “outstanding” nature of the water quality in the lower Ngaruroro River.
69. Ms McArthur notes that it is inappropriate to compare water quality against a pristine (unpolluted) standard (para 66) and with that I agree, but being in the top 25% of national water quality data sets for some elements (and in the poorest 25% of others) does not, in my opinion, qualify as “outstanding”. There are many rivers which do not have an E. coli issue for example and that does not make them, in my opinion, outstanding.
70. Ms McArthur discusses (in a number of places in her evidence) threats or potential threats and risks of adverse effects. As I understand it the purpose of the WCO application process is to prove or provide evidence that a feature is outstanding and worthy of protection by an order and that a risk of degradation is a secondary or later consideration as to the form of protection, rather than driving the determination of if a WCO protection level is warranted.
71. I have therefore not made further comment on the threat section of Ms McArthur’s evidence [paras 71-74].
72. In a similar vein in paras 75- 77, Ms McArthur undertakes a comparison of water quality attributes and limits in the WCO application with that of the TANK. In my opinion this is not relevant ahead of the larger question of the proof of an outstanding condition being present and warranting the granting of a WCO.
73. Ms McArthur states the importance of connectivity between the upper and lower Ngaruroro. I agree, passage / connectivity for all aquatic species and organic matter is very important. Passage (connectivity) is facilitated by sufficient water at the right times of year, relating to lifecycles of aquatic species and an absence of barriers to their movement. Passage is a typical function of a water way but I am unaware of what a passage of an “outstanding” nature might be. Rather passage is a typical function of a waterway that can be impinged upon by poor management rather than a character of a system that might have a special or outstanding condition.
74. Paragraphs 80-88 of Ms McArthur’s evidence reflect upon the threat classification system and biodiversity value of freshwater fish. I am unclear about what this section of her evidence seeks to add in terms of proof of an outstanding attribute or character of the river. At a national level, some threatened fish remain trending down (in decline) and some are improving - the updated fish threat classification (Dunn et al 2017) shows three taxa have
20 improved conservation status and two have decreased in status. Longfin eel numerical improvements have meant there was consideration that they might come off the threat list (noting that they did not); however, redfin bully have. That said threat status of some of the fish fauna is not a measure of the outstanding condition of a water way. Most waterways have threatened taxa. Like the avian fauna, a stable population of one or more of the most at risk taxa in New Zealand (i.e. Nationally Critical or Nationally Endangered) would, in my opinion, fit an outstanding criterion. This is not the case in the Ngaruroro River.
75. Ms McArthur places emphasis on torrentfish, (para 83) stating that being endemic and the only member of a particular family gives them a “unique” and special biodiversity value. I disagree, they are classified as an “At Risk” - declining species, as are longfin eel, koaro and many others. Torrentfish are wide spread (see Attachment 2 - NIWA distribution map), and frequently sampled. A recent NIWA publication (NIWA 2016) shows that new analysis suggests torrentfish are the 11th most commonly sampled species, and are not in decline. Their population trend is currently being debated.
76. As I noted above, in my opinion, the threat class - Nationally vulnerable species - is too low a test to confer “outstanding”, but I would accept Nationally Endangered and Nationally Critical fish populations as a valid case for an outstanding classification – “vulnerable” includes many fish still widely distributed and recorded in many rivers (e.g. lamprey).
77. At para 85 Ms McArthur addresses the assessment of “outstanding” in terms of an indigenous fish attribute, noting there is no standardised method. She suggests that community intactness is a relevant criterion (referencing Joy et al 20183). However, where “outstanding” is a measure of rank or the top end of a gradient of values (as I understand the test to be), then community intactness would be an attribute to test against the wider national rivers fish community’s intactness, and its rank or level of special character determined.
78. I do not see such an analysis in Ms McArthur’s evidence.
3 Joy, M; Foote, K; McNie, P. 20158. Decline in New Zealand’s freshwater fish fauna: effect of landuse. Marine and freshwater research 70(1) pgs 114-124, 2018.
21 79. I concur with Harper (2017) that the presence of values, significant, or otherwise, do not, in and of itself, confer an outstanding condition. Many rivers have such values.
80. The assertion (following Maseyk et al 20184) that a significant ecological value, such as: an intact indigenous fish community, habitat for threatened – nationally vulnerable indigenous fish, intact submerged aquatic submerged ecosystems and naturally uncommon ecosystems that are endangered, should confer an “outstanding” condition is only valid, in my opinion, where those conditions are sufficiently special, ranking above most other rivers in the Nation, for that attribute.
81. “Intact” indigenous fish communities are not that uncommon, most of the other high value rivers in the Hawke’s Bay region (e.g. Wairoa, Tukuituki, and Tutaekuri), have comparable or better fish fauna communities with more nationally. It is my opinion if it does not rank as “outstanding” on a regional scale, then it cannot rank as “outstanding” on a national scale.
82. One other aspect around intact communities is that there seems to be a lack of consideration of the extent to which the exotic species, and in particular trout, play in moderating native fish numbers and presence. I do not see this consideration in Ms McArthur’s evidence.
83. Lastly, because a feature, be it common or naturally uncommon (as are braided rivers), is endangered, does not make the feature “outstanding”. It may make management and protection a priority, but it does not make the feature in and of itself “quite out of the ordinary on a national basis”.
84. Again, I do not see an evidential based assessment of outstanding in the evidence of Ms McArthur in this section.
85. Ms McArthur states that there are 16 indigenous species, at odds with my reported 13. The difference is that she has included the estuarine “wanderers”: yellow and grey mullet and the estuarine triplefin (a bully). My analysis excluded these as they primarily inhabit marine and estuarine waters than freshwater and river habitat. This absence makes no difference to my assessment as I also excluded them from my national comparative data.
4 I could find no reference to this publication on the Bay of Plenty Regional Council web site and library whom list publications by consultant company and through a general search.
22 86. Ms McArthur appears to put aside the conclusion of Jellyman and Sinton’s 2017 report5 comparing regional lower river fish communities to determine if the lower Ngaruroro fish community is markedly different from other large Hawke’s Bay rivers. Their conclusion is that the fish community is not different.
87. In paragraph 97 Ms McArthur states that there are additional “unique” characteristics of the fish community in the Ngaruroro, one of which is the presence of all bully (Gobiomorphus) species. This is not factually correct; the non-migratory upland bully has not been recorded in lower Ngaruroro River habitats. As a technicality, I also point out that Tarndale bully (G. alpinus), is not present – being a South Island alpine species. McArthur then goes on to state that the Ngaruroro is “unique” for providing a diverse variety of habitats that supports the full diversity and range of bully species. This is factually incorrect. The Tukituki, Waikari, Tutaekuri (but not in the lower river) and Wairoa Rivers (from the NIWA FWDB) also have the same diversity and range of bully species as the Ngaruroro.
88. With respect to Torrentfish, the statement (para 99) that their abundance and presence is a unique characteristic of the lower Ngaruroro River is factually incorrect. Ms McArthur herself references the survey report of Jellyman and Sinton (2017) whereby recent surveys shows that torrentfish are typical of lowland large rivers in the region - they were the third most abundant species caught in the wider survey.
89. At para 100 McArthur also suggests that the presence of dwarf galaxias is a defining characteristic. I agree that it is a valuable attribute, but I note that the Tukituki River also has a population of dwarf galaxias (although more inland) and, in regard to the data in the NIWA FWDB, the dwarf galaxias population is more substantial in the Tukituki than the Ngaruroro.
90. Ms McArthur then discusses the RiVAS (Hughey et al 20126) report findings. I reproduce their spread sheet analysis in Attachment 3. They found that it was one of four “best” fish rivers (in terms of fish attributes) in the region (noting the Wairoa was the best) and labelled it of “national importance”. However, in that analysis there was no national level evaluation in this labelling, and the
5 Jellyman, P; Sinton, A. A comparison of the lower river fish communities in large Hawke’s Bat rivers. September 2017. NIWA client Report No. 2017138CH
6 Hughey, K; Clapcott, J; Goodwin, E; Jonas, H; Cheyne, J; Cameron, F; Maxwell, I; Sharp, T. 2012. Native fish in Hawke’s Bay: development and application of the river values assessment system (RiVAS and RiVAS+). LEaP Research paper No. 18
23 analysis does not then lend itself to that of a test of “outstanding” in terms of a WCO. Again, it shows that the Ngaruroro has value and is significant habitat but not that it is “outstanding”.
91. Ms McArthur has a section (para 111- 119) discussing the IBI model and fitting the actual species richness against the model prediction to show that the lower Ngaruroro has an expected (“intact”) community. As I have already noted, so too do many rivers in the region and even more nationally. As noted by Ms McArthur in the water quality section, the test is not a comparison to a pristine condition, but whether the character / attribute or condition is outstanding. If there were few or no other intact fish communities nationally, then this (in my understanding of the test) would trigger an “outstanding” outcome, but that is not the case.
92. Ms McArthur in para 120 discussing braided river considerations again uses the word unique to describe the braided character of the Ngaruroro. The word unique is used 12 times in her evidence and in no instance of its use do I see evidence of it applying as per the dictionary definition. The braided character of the lower Ngaruroro River is modified and is very similar, if not the same, as many other braided rivers with similar sized catchments. Other than the Ngaruroro being the only Ngaruroro and therefore unique unto itself, I do not find the braided character of the Ngaruroro unique or of any special (outstanding) character compared to other braided rivers.
93. It is true that there are fewer braided rivers in the North Island than the South Island, and that they are naturally uncommon (because of the requirements of their formation). Braided rivers are a product of climate, hydrology and substrate (geology) which dictates their location and abundance. 59% of the countries braided rivers are in Canterbury and, as O’Donnell (20107) shows, Hawke’s Bay is the sixth-ranked region in New Zealand in terms of area of braided river.
7 O’Donnell (2010) Threatened fauna of the Canterbury Region. Powerpoint presentation at Braid meeting (on web site http://braid.org.nz/braided-rivers/)
24
94. Nationally then, accepting all braided rivers are of value, they are naturally uncommon and threatened. This does not make the Ngaruroro in and of itself “outstanding” - it is not the best representative or largest or most diverse (in habitat and fauna) of the nations braided river systems.
95. From para 123 onwards Ms McArthur discusses the threats to indigenous fish. I do not consider the level of threat or risk to a value or area to be a measure of the outstanding character of a feature(s) or attribute(s). The consideration of how to protect or manage threat has many avenues and are not, in my understanding, a consideration of merit of outstanding but rather a secondary aspect if the attributes, etc. are found to be outstanding.
CONCLUSION
96. In summary I see an array of values outlined in the evidence of Ms McArthur, and I largely agree that those values are present in the lower Ngaruroro River. There are several factual errors in some of the reported conditions of the fishery and no proof that the lower Ngaruroro is unique or special in ways above and beyond other regional rivers. There is a lack of analysis and evidence at a national scale for the Ngaruroro attributes (as I understand the test of outstanding to be) and without this analysis she has not been able to effectively test, or prove, the river as outstanding.
97. My analysis does undertake a national comparison test and it does not rank the lower Ngaruroro in the top 10% of national similar-sized lowland rivers.
98. The one attribute that might be outstanding (and, therefore, convey an outstanding classification) is the population of the
25 black-fronted dotterel. However, the population range data is problematic (old) and it is unclear if the current river population is, or is not, 5% or more of the national population (the threshold).
Vaughan Francis Keesing
25 January 2019
26 ATTACHMENT 1 - “AQUATIC ECOLOGY OF THE LOWER NGARURORO RIVER: ECOLOGICAL ASSESSMENT AND COMPARISON AT A LOCAL, REGIONAL AND NATIONAL SCALE.” BOFFA MISKELL LIMITED (BML REPORT), 20 FEBRUARY 2018.
27
Aquatic ecology of the lower
Ngaruroro River Ecological assessment and comparison at a local, regional and national scale Prepared for HORT NZ & HBRC
20 February 2018
Document Quality Assurance
Bibliographic reference for citation: Boffa Miskell Limited 2018. Aquatic ecology of the lower Ngaruroro River: Ecological assessment and comparison at a local, regional and national scale. Report prepared by Boffa Miskell Limited for HORT NZ & HBRC.
Prepared by: Jeremy Garrett-Walker Ecologist Boffa Miskell Limited
Reviewed by: Dr Vaughan Keesing Senior Ecologist Boffa Miskell Limited
Status: Final Revision / version: 8 Issue date: 20 February 2018
Use and Reliance This report has been prepared by Boffa Miskell Limited on the specific instructions of our Client. It is solely for our Client’s use for the purpose for which it is intended in accordance with the agreed scope of work. Boffa Miskell does not accept any liability or responsibility in relation to the use of this report contrary to the above, or to any person other than the Client. Any use or reliance by a third party is at that party's own risk. Where information has been supplied by the Client or obtained from other external sources, it has been assumed that it is accurate, without independent verification, unless otherwise indicated. No liability or responsibility is accepted by Boffa Miskell Limited for any errors or omissions to the extent that they arise from inaccurate information provided by the Client or any external source.
Template revision: 20170727 0000
File ref: W17067_BML_Ngaruroro_Aquatic_Report_20180220_v8.docx
Cover photograph: [Ngaruroro River, © BML, 2017]
CONTENTS
1.0 Introduction 1
1.1 Report Scope 1 1.2 Report layout 1
2.0 Methodology 2
2.1 Water quality 2 2.2 Macroinvertebrates 3 2.3 Fish 4 2.4 Avian Methodology 4 2.5 Assessment of Outstanding 6
3.0 Lower Ngaruroro River physical habitat 8
3.1 Expected habitat condition of a braided river in a natural state 8 3.2 Current physical habitat condition in Ngaruroro River 8
4.0 Lower Ngaruroro River ecology 14
4.1 Water quality 15 4.2 Macroinvertebrates 26 4.3 Fish biodiversity 29 4.4 Avifauna 30 4.5 Ngaruroro Ecology Summary 38
5.0 Hawkes Bay rivers - Regional ecological comparison 39
5.1 Water quality 39 5.2 Macroinvertebrates 50 5.3 Fish biodiversity 52 5.4 Regional summary 55
6.0 National rivers - ecological comparison 56
6.1 Water quality 56 6.2 Macroinvertebrates 65 6.3 Fish biodiversity 67 6.4 Avian population estimates and national proportions 70
7.0 Assessment of outstanding 72
8.0 References 74
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
List of Figures
Figure 1. The OSNZ grid squares that encompass the Lower Ngaruroro River and surrounds (highlighted yellow)...... 6
Figure 2: Map of the lower Ngaruroro River, showing locations of modification as observed during the site visit. Captions for the inserted photos can be found in Table 2 ...... 13
Figure 3: Water temperature (oC) as measured at each monitoring site along the Ngaruroro River...... 18
Figure 4: Dissolved oxygen concentrations (mg/L) between the six monitoring locations along the Ngaruroro River...... 18
Figure 5: Black disk measurements (m), as a measure of water clarity, as recorded at each monitoring location along the Ngaruroro River...... 19
Figure 6: Turbidity (NTU), as recorded at each monitoring location along the Ngaruroro River...... 20
Figure 7: Total nitrogen concentrations recorded at four of the monitoring locations along the Ngaruroro River...... 20
Figure 8: Total phosphorus concentrations recorded at four of the monitoring locations along the Ngaruroro River...... 21
Figure 9: Dissolved inorganic nitrogen concentrations recorded at four of the monitoring locations along the Ngaruroro River...... 22
Figure 10: Dissolved reactive phosphorus concentrations recorded at six monitoring locations along the Ngaruroro River...... 22
Figure 11: Nitrate concentrations recorded at six monitoring locations along the Ngaruroro River...... 23
Figure 12: Nitrite concentrations recorded at six monitoring locations along the Ngaruroro River...... 24
Figure 13: Ammonium concentrations recorded at two monitoring locations along the Ngaruroro River...... 24
Figure 14: pH recorded at six monitoring locations along the Ngaruroro River...... 25
Figure 15: E. coli concentrations recorded at six monitoring locations along the Ngaruroro River...... 26
Figure 16: Macroinvertebrate community index (MCI) scores calculated from eight monitoring locations along the Ngaruroro River...... 28
Figure 17: EPT taxa richness from eight monitoring locations along the Ngaruroro River...... 29
Figure 18: Dissolved oxygen (mg/L) concentrations in 10 rivers in the Hawkes Bay region...... 40
Figure 19: Black disk measurements (m) in 10 rivers in the Hawke’s Bay region...... 41
Figure 20: Turbidity recordings (NTU) in 10 rivers in the Hawke’s Bay region...... 42
Figure 21: Total nitrogen (TN; mg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 43
Figure 22: Total phosphorus (TP; mg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 44
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 Figure 23: Dissolved inorganic nitrogen (DIN; mg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 45
Figure 24: Dissolved reactive phosphorus (DRP; mg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 46
Figure 25: Nitrate (NO3; µg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 47
Figure 26: Nitrate (NO2; µg/L) concentrations in 10 rivers in the Hawke’s Bay region...... 48
Figure 27: E. coli (MPN/100 mL) concentrations in 10 rivers in the Hawke’s Bay region...... 49
Figure 28: Macroinvertebrate community index (MCI) scores for eight of the ten SoE rivers in the Hawke’s Bay region...... 51
Figure 29: EPT taxa richness for eight of the ten SoE rivers in the Hawke’s Bay region...... 52
Figure 30: Dissolved oxygen (mg/L) concentrations in 17 national lowland rivers...... 57
Figure 31: Black disk measures (m) for water clarity in 17 national lowland rivers...... 58
Figure 32: Turbidity (NTU) for water clarity in 17 national lowland rivers...... 59
Figure 33: Dissolved reactive phosphorus (DRP) concentrations in 17 national lowland rivers...... 60
Figure 34: Nitrate (NO3) concentrations in 17 national lowland rivers...... 61
Figure 35: Ammonium (NH4) concentrations in 17 national lowland rivers...... 62
Figure 36: pH levels in 17 national lowland rivers...... 63
Figure 37: E. coli concentrations in 17 national lowland rivers...... 64
Figure 38: MCI values for 17 national lowland rivers...... 65
Figure 39: EPT taxa richness for 14 of the 17 national lowland rivers...... 66
List of Tables
Table 1: National rivers where macroinvertebrate data were not available from NIWA dataset, including where data was sourced and what information could be gathered...... 3
Table 2: Captions for the images found in Figure 2...... 14
Table 3: Location of monitoring sites along the Ngaruroro River, including the upper Kuripapango site ...... 15
Table 4: Chronic effects levels for water quality parameters with respect to maintaining quality freshwater communities...... 17
Table 5: Monitoring locations for the eight monitoring sites where macroinvertebrate data were available...... 26
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Table 6: MCI & QMCI score classification meanings (from Stark and Maxted 2004) ...... 27
Table 7: NIWA FFDB records of fish observed in the Ngaruroro mainstem between the Waitangi Estuary and Cableway ...... 30
Table 8. Threatened and At Risk avifauna species identified within the OSNZ squares and recorded during surveys of the Ngaruroro River and surrounds...... 31
Table 9: Rivers included in the State of the Environment monitoring and reporting by the Hawkes Bay Regional Council, including their catchment size and no of locations where datasets are available from NIWA...... 39
Table 10: Descriptive statistics for dissolved oxygen in 10 Hawkes Bay rivers, including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification...... 40
Table 11: Descriptive statistics for black disk water clarity in 10 Hawke’s Bay rivers...... 41
Table 12: Descriptive statistics for turbidity (NTU) in 10 Hawke’s Bay rivers ...... 42
Table 13: Descriptive statistics for total nitrogen (TN; mg/L) concentrations in 10 Hawke’s Bay rivers 43
Table 14: Descriptive statistics for total phosphorus (TP; mg/L) concentrations in 10 Hawke’s Bay rivers ...... 44
Table 15: Descriptive statistics for dissolved inorganic nitrogen (DIN; mg/L) concentrations in 10 Hawke’s Bay rivers...... 45
Table 16: Descriptive statistics for dissolved reactive phosphorus (DRP; mg/L) concentrations in 10 Hawke’s Bay rivers ...... 46
Table 17: Descriptive statistics for nitrate (NO3; µg/L) concentrations in 10 Hawke’s Bay rivers...... 47
Table 18: Descriptive statistics for nitrate (NO2; µg/L) concentrations in 10 Hawke’s Bay rivers...... 48
Table 19: Descriptive statistics for E. coli (MPN/100 mL) concentrations in 10 Hawke’s Bay rivers. .... 49
Table 20: Mean and median water quality results of the lower Ngaruroro River when compared against the lower sections of nine other Hawke’s Bay rivers...... 50
Table 21: Descriptive statistics for macroinvertebrate community index (MCI) scores in eight of the ten Hawke’s Bay rivers...... 51
Table 22: Descriptive statistics for EPT taxa richness in eight of the ten Hawke’s Bay rivers ...... 52
Table 23: Fish taxa presence/absence between selected Hawkes Bay rivers. 1 = taxa present in NIWA FFDB records...... 54
Table 24: Fish metric summary for each Hawkes Bay selected river, including ranking each metric (grey columns)...... 55
Table 25: Summary table of how parameters discussed above rank for the lower Ngaruroro River on a regional basis...... 55
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 Table 26: Descriptive statistics for dissolved oxygen (mg/L) in 17 national lowland rivers ...... 57
Table 27: Descriptive statistics for black disk measurements (m) in 17 national lowland rivers ...... 58
Table 28: Descriptive statistics for turbidity (NTU) in 17 national lowland rivers ...... 59
Table 29: Descriptive statistics for dissolved reactive phosphorus (DRP) concentrations in 17 national lowland rivers ...... 60
Table 30: Descriptive statistics for nitrate (NO3) concentrations in 17 national lowland rivers...... 61
Table 31: Descriptive statistics for Ammonium (NH4) concentrations in 17 national lowland rivers...... 62
Table 32: Descriptive statistics for pH levels in 17 national lowland rivers ...... 63
Table 33: Descriptive statistics for E. coli concentrations in 17 national lowland rivers ...... 64
Table 34: Descriptive statistics for MCI values for 17 national lowland rivers ...... 65
Table 35: Descriptive statistics for EPT richness for 14 of the 17 national lowland rivers ...... 66
Table 36: Species observed in 17 national lowland rivers. Ngaruroro River has been highlighted in red to allow for easy identification...... 68
Table 37: Number of species found in 17 national lowland rivers...... 69
Table 38: Threat classifications and the assigned threat classification indices (TCI) values for the purpose of comparing the 'importance' of the native fish diversity between national rivers. .. 70
Table 39. Summary of the avifauna species that utilise the Lower Ngaruroro River and whether the reach is nationally outstanding for each species...... 70
Table 40: Summary table of how parameters discussed above rank for the lower Ngaruroro River on a regional and national scale...... 73
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
1.0 Introduction
1.1 Report Scope
Boffa Miskell have been engaged to collect and collate ecological information regarding fish, riverine birds, physical habitat condition (water quality and riparian and substrate condition), and aquatic macroinvertebrates in the Ngaruroro River below (downstream) of the Whanawhana cable way to the estuary. We are requested to then highlight values/condition along the lower river and to compare those at a regional and national scale to establish a “ranking” of the condition (and values) of features and the habitat of the lower Ngaruroro. Lastly, this analysis is to assess what single parameter, and if as a whole, the lower river can be considered outstanding at a national level (as required by a Water Conservation Order).
1.2 Report layout
Following a description of the methods used to attain and use data (Section 2.0), this report addresses (Section 3.0) the Ngaruroro River’s physical habitat in the absence of human influences and then the physical habitat as it is today with a focus on the level of modification (riparian vegetation composition, riverbank form, flow, gravel bed, and the braided pattern). Secondly the ecology (including assigning a value context) of the lower Ngaruroro River (i.e. water quality, fish fauna, avian fauna and macroinvertebrate fauna) is summarised, discussed and assessed (Section 0.). Thirdly a comparison is made of the aquatic features and conditions across the regions rivers (Section 5.0) and a selection of national rivers (Section 6.0) to test the outstanding nature of the system and its aquatic features (Section 7.0).
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 1
2.0 Methodology
The ecological condition (and values) of the lower Ngaruroro river was assessed in three ways:
i. the ecology (water quality, macroinvertebrate, fish, and avifauna) of the lower river was determined along a downstream gradient; ii. the overall ecological condition was compared against nine other rivers within the Hawke’s Bay region; iii. the overall ecological condition was compared against 16 other similar rivers on a national scale.
To allow for this assessment and comparison to be made, water quality, macroinvertebrate, fish, and avifauna data were collected from a range of sources. These data were processed and filtered to eliminate erroneous data (data whose credibility or relevance could not be assured), and to remove data points with suspicious values. The filtered data was then arranged in a manner to allow for analyses. Analyses predominantly included calculating descriptive statistics and depicting these via box plots (thus incorporating many years of data). These results then allowed for ranking of each parameter according to mean and median values to determine how each parameter performed on a local, regional, and national scale. Detailed methodologies used for water quality, macroinvertebrates, fish, and avifauna are described below.
Details of which monitoring locations and/or rivers were selected can be found at the beginning of Sections 4.0, 5.0, 6.0 and in the Appendices.
2.1 Water quality
Water quality data were sourced from the New Zealand National Institute of Water and Atmospheric Research (NIWA) Metadata Catalogue. Data were firstly collected for all New Zealand rivers where monitoring is undertaken by regional councils and/or NIWA, before being filtered to remove data for those rivers not assessed in this report. Data which had been flagged as below the detection limit, questionable, or synthetic, were then removed. Coordinates of monitoring locations were then mapped to isolate those locations situated on the lower sections of the selected river(s).
The remaining data were then organised in a manner to facilitate analyses. Water quality throughout the lower Ngaruroro River was converted to box plot figures to depict potential trends along the river gradient and/or isolate sections of the river which had good or poor water quality. For comparison of the lower Ngaruroro River against regional and national rivers, descriptive statistics were generated using the ‘data analysis’ add-on in Microsoft Excel© to be able to rank each river according to the mean and median value of each parameter.
Data used for water quality analyses was accessed from the NIWA Metadata Catalogue on 22/08/2017 and used according to the following terms of use:
The data are protected by copyright owned by the Ministry for the Environment on behalf of the Crown and are licensed for re-use under a Creative Commons Attribution 3.0 New Zealand Licence. In essence, you are free to copy, distribute and adapt the material, as long as you abide by the licence terms and attribute the work in the following manner:
2 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
"National indicator data for river condition in New Zealand - collected by Regional Councils and the National Institute of Water and Atmospheric Research (NIWA), collated and processed by NIWA and protected by copyright owned by the Ministry for the Environment on behalf of the Crown".
Disclaimer:
Whilst reasonable measures have been taken to ensure the accuracy of the data, the Ministry, the Regional Councils and NIWA give no warranty in relation to the data, including the accuracy, reliability and suitability and accept no liability whatsoever in relation to any loss, damage or other costs relating to the use of any data, or any compilations, derivative works or modifications of the data.
Data available through the NIWA Metadata Catalogue was comprehensive enough to not warrant collection of data from supplementary resources.
2.2 Macroinvertebrates
Macroinvertebrate data were primarily sourced from the NIWA Metadata Catalogue (including SOE data) and processed in the same fashion as the water quality data. However, macroinvertebrate data for some rivers were absent from this dataset and had to be sourced from supplementary peer-reviewed documents (Table 1). Refer to Appendix 1 for monitoring locations on each river and the years for which data were available.
Table 1: National rivers where macroinvertebrate data were not available from NIWA dataset, including where data was sourced and what information could be gathered. River Source Information available Kaituna River Hamill (2014) MCI score Rakaia River Sagar (1986) Community composition Gray & Harding (2010) Community composition Rangitaiki River Bay of Plenty Regional Council (2014) MCI score Wilding (2001) MCI score Waimakariri River Gray & Harding (2010) Community composition Whakatane River Wilding (2001) MCI score
Where possible, macroinvertebrate community index (MCI) scores and Ephemoptera, Plectoptera, and Trichoptera (EPT) taxa richness was calculated to determine the health of the macroinvertebrate community (refer to Section 4.2) for detailed descriptions of MCI and EPT indices, including calculations used).
Descriptive statistics (especially mean and median values) and box plots were used to rank the MCI and EPT richness of the lower Ngaruroro River against regional and national rivers. Macroinvertebrates of which individual MCI scores have not been assigned were excluded from the analyses.
Macroinvertebrate data sourced from the NIWA Metadata Catalogue on 22/08/2017 and were subject to the same terms and conditions as the water quality data.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 3
2.3 Fish
Fish data was sourced from the NIWA administered New Zealand Freshwater Fish Database (NZFFD). To avoid collecting fish data from rivers which were not included in this report yet had the same name, the NIWA assigned catchment number was used. Using the NIWA assigned catchment number allowed for excluding major rivers and/or tributaries from the resulting datasets (refer to Appendix 2 for list of rivers and catchment numbers).
The fish datasets were processed to remove taxa which were not relevant to this report, including marine taxa (e.g. yelloweye mullet, black flounder), non-fish taxa (e.g. freshwater crayfish, freshwater mussels), and unidentified taxa (e.g. unidentified bully, unidentified galaxiid). Monitoring occasions where no fish were recorded were also removed. Abundance data for fish were not consistent so fish were analysed on a presence absence.
Firstly, the fish community of the lower Ngaruroro River was described. Secondly, fish value was assessed on a regional and national scale by comparing the total taxa richness, number of native taxa, number of introduced taxa, and the number of threatened/at risk taxa (according to Goodman et al., (2014)). To test “outstanding” values we eliminated all common and ubiquitous taxa and compared At Risk and Threatened taxa presence against a range of other similar catchment and river sizes across New Zealand. This was done because the differential capacity of taxa richness as a whole is marginal with most big rivers having a total taxa richness near 15 and we did not consider a difference of one or two taxa to be very definitive. However, by using threatened and at risk criteria (which are from a conservation perspective higher value taxa) this better adheres to the purpose of establishing an “outstanding” waterway.
2.4 Avian Methodology
Data from the Ornithological Society of New Zealand’s atlas (C. J. R. Robertson, Hyvonen, Fraser, & Pickard, 2007) was collated from seven 10 km x 10 km grid squares (280, 617; 281, 617, 282, 617; 283, 617; 284, 617; 281, 616; 282, 616) which encompass the Lower Ngaruroro River (Figure 1). The primary and secondary habitats1 for each of the species recorded within these grid squares was obtained from Heather & Robertson (2005) along with each species’ New Zealand threat status according to Robertson et al (2016). The species list obtained from the OSNZ atlas served as a base list of avifauna species recorded within the wider Ngaruroro River area and therefore potentially present at or near the WCO application site.
Further literature (published and unpublished) and website searches were undertaken to obtain additional information regarding bird species known to utilise habitats within and directly adjacent to the Lower Ngaruroro River. No field investigations were undertaken.
Once collated, the data were filtered so that only native and endemic Threatened and At Risk avifauna species of the Lower Ngaruroro River were included in further analyses because these species are of most conservation concern. Vagrant and international migrant species, as well as game species were excluded from further analyses as they are species about which a WCO is not concerned. Species that exclusively utilise coastal/estuarine habitats were also excluded as
1 For the purpose of this report, primary habitat refers to the habitat in which the species spends most of its time. Secondary habitats are other habitat types which the species may also utilise.
4 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
the WCO application applies to the ‘main stem of the Ngaruroro River from Whanawhana cableway downstream to the inland limit of the coastal marine area’ (WCO application reference) and as such does not include coastal/estuarine habitats.
Assessments were then made to determine whether the Lower Ngaruroro River provides nationally ‘outstanding’ habitat for each Threatened and At Risk species present. For a waterbody to warrant protection in a water conservation order, the waterbody must be considered outstanding when viewed from a national perspective (i.e. out of the ordinary on a national basis) ((Special Tribunal to Consider an Application for a Water Conservation Order for the Hurunui River, 2009). In this report, for avifauna, nationally outstanding habitat for a species was defined in the Lower Ngaruroro River as supporting, at any one time, 5% or more of the national population of a species. This definition was derived from Hughey et al (2012) where it was “decided for Canterbury and Tasman to introduce a ‘species stronghold’ criterion into the decision support system for defining priorities, i.e., if a river contains 5% or more of a population of a ‘threatened or at risk’ species then it is of national importance”. This criterion is also consistent with the decisions made for the Oreti River and Rangitata WCO applications (Oreti WCO final decision doc 2007, Rangitata River WCO application 2002). In the Oreti River WCO Final Decision Document the special tribunal that produced the report (and was appointed by the Minister for the Environment) states that “We accept … the assertion that at least some parts of the Oreti River provide outstanding wildlife habitat. In particular, the 5 % “threshold” of the national population of an endangered species”.
To test this criterion, estimates of the Lower Ngaruroro River population for each bird species of concern were compared to their national population size. It must be noted that national population size estimates are not always accurate, agreed upon or current. Ngaruroro River populations were based on available survey data; these data were from historic Wildlife Service (former name of DOC), DOC and OSNZ surveys conducted between 1962 and 1993 (Maxwell, Adams, & Walls, 1993; Parrish, 1988), and a partial survey of the Lower Ngaruroro River conducted by Stephenson (2010) in 2009. More recent surveys of the Lower Ngaruroro River have not been conducted. National population estimates were based on the most recent and available estimates within scientific literature, and if these estimates differed, a population size range was adopted. It must be noted that since writing this report, a more recent estimate of national avifauna populations has been sourced. The reference has been reviewed, however changes in national population sizes for the species of interest within this assessment did not alter whether Ngaruroro avifauna populations were considered outstanding or not on a national scale. Consequently, national population numbers were not updated using this information. The exception to this was the black-fronted dotterel; the Ngaruroro population was found to be nationally outstanding with the older population estimate (as discussed in Section 4.4 of the report) and as such we wanted to test if the new population estimate altered this status.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 5
Figure 1. The OSNZ grid squares that encompass the Lower Ngaruroro River and surrounds (highlighted yellow).
2.5 Assessment of Outstanding
The court and hearing panels have reasonably defined or illuminated what is meant in a WCO context of “outstanding”.
In the Kawarau River WCO application (amendments) Judge Jackson wrote: “in part 9 of the RMA the planning tribunal wrote: “the test as to what is outstanding is a reasonably rigorous one, …to qualify as outstanding a characteristic would need to be quite out of the ordinary on a national basis”…
6 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
However, this is not further defined or refined as to what “quite out of the ordinary” means in a comparative context.
We note that the threat status or risk of the water body is not a determining factor in making a WCO (Rangitata Report, second Gowan Tribunal and Kawarau decision) - only the presence of characteristics which are “outstanding”, but that an application should still recognise any threats to the outstanding characteristics.
It has been stated that the purpose of water conservation orders is to provide recognition of the outstanding amenity or intrinsic values of water bodies and that a water conservation order may provide for any of the following:
• the preservation as far as possible of the water body’s natural state • the protection of characteristics which the water body has or contributes to: o as a habitat for terrestrial or aquatic organisms o as a fishery o for its wild, scenic, or other natural characteristics: o for scientific and ecological values: o for recreational, historical, spiritual, or cultural purposes: • the protection of characteristics which any water body has or contributes to, and which are considered to be of outstanding significance in accordance with tikanga Māori.
As stated above the assessment of outstanding for an avian species was determined by recognition of use of the habitat by at least 5% of a national species population. We follow this threshold here.
There are less clear approaches in regard to other ecological components (habitat condition, native fish taxa richness, water quality or quality of the macroinvertebrate communities) and previous decisions do not articulate what “quite out of the ordinary on a national basis” means. We adopt the following thresholds:
For water quality – the top 10% of the compared rivers -i.e. the top 2 rivers in terms of water quality parameters was the test.
For Fish taxa richness, the top 10% of the tested rivers (i.e. in this analysis the top 2 rivers of the 17 best national rivers of similar size and position compared) was the test.
With regard to macroinvertebrates a MCI > 120 is the preferred approach (to represent “out of the ordinary” – but analysis showed no mean MCI value for any river used here was over 120 (the threshold for “excellent”) and so we lowered this threshold to MCI > 100 (“Good”) - and then considered the top 10% ranking of the tested rivers (i.e. the top 2).
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 7
3.0 Lower Ngaruroro River physical habitat
3.1 Expected habitat condition of a braided river in a natural state
Section 199(1)(a) and (2)(a) of the RMA pertains to recognising and sustaining waters in their “natural state”. The Court in Rangitata held in [20] that “Natural state means towards the pristine end of the artificial/polluted to pristine continuum”. The physical habitat of a braided river in a natural state can be predicted with reasonable certainty. Prior to human clearance, the land surrounding the Ngaruroro River would have been a podocarp (native conifer) forest. This native vegetation would have extended to the riparian zone of the river. The floodplain would have been interspersed with natural wetlands that were periodically connected to the river during floods. These wetlands would have contained a high biodiversity of native wetland flora and fauna. The nature of a lowland braided river suggests there would have been sections where the river channel was restricted due to natural banks; however, large portions of the river would have had a low terrace separating the river channel and the flood plain. In the lower Ngaruroro River, the floodplain would have extended for several kilometres. This floodplain would likely have been dominated by kahikatea and pukatea tall forest. In the absence of a flood protection scheme and permitted water takes, the Ngaruroro River flow would have regularly fluctuated in its occupation of space in response to rainfall. The braids in the river would have naturally migrated across the channel in response to the changing riverbed. This channel migration would have seen the frequent creation of isolated islands which avifauna would have utilised for nesting and roosting from time to time.
3.2 Current physical habitat condition in Ngaruroro River
Examples of the current physical habitat condition which are discussed in this section are provided in the photos in Figure 2. Captions for the photos are provided in Table 2.
3.2.1 Riparian
A recent assessment of the ecological values of the lower Ngaruroro River was conducted by MWH (2011) to assist with the creation of an Ecological Management and Enhancement Plan. This assessment found the riparian vegetation was dominated by introduced species, especially Salix spp. (willow). In total, exotic vegetation comprises approximately 53% of the river channel and riparian margin (29% - exotic grassland/herbfield; 24% - exotic forest). Native vegetation covered approximately 0.3% of the river and riparian corridor. A breakdown of vegetation classes, as found in MWH (2011), is as follows:
• Exotic grassland/herbfield – 676 ha
• Exotic forest – 555 ha
• Exotic scrub – 92 ha
8 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
• Exotic treeland – 65 ha
• Native shrubland – 3.9 ha
• Native treeland – 2 ha
• Native forest – 1.2 ha The extensive exotic forest/treeland areas are the result of willow edge flood-protection plantings (MWH, 2011). Furthermore, historic tree lupin plantings for erosion control in the upper mountain ranges now provides a seed source which is easily transported to the lower Ngaruroro. The upper Ngaruroro is dominated by native vegetation which extends to Whanawhana (MWH, 2011). However, the native broadleaf and kanuka forest at Whanawhana rapidly becomes isolated and individual specimens in the upper half of the flood protection scheme zone. There is only occasional natural native vegetation below Roys Hill. Aquatic weeds regularly spread throughout the lower Ngaruroro, resulting in dense weed mats along the river margins and on newly disturbed gravel beds (Environmental Management Services Limited, 2016; Hawke’s Bay Regional Council, 2017; MWH, 2011). Spread of these weeds are annually managed through beach raking (see 3.2.4) within the flood protection scheme zone.
3.2.1.1 Exotic riparian vegetation
The spread, densities, current effects, and future potential effects of exotic riparian plantings (primarily willow) became apparent during a site visit in December 2017. During this site visit, willows, poplars, and lupin were observed throughout the riparian zone between the cableway and the estuary. Furthermore, in the upper section of this stretch (in the absence of riverbed disturbance regimes such as gravel raking and / or gravel extraction) large established willows were observed within the riverbed zone and young willow saplings were observed in high densities growing in dry riverbed habitats.
In 1984 Parrish (1988) noted willows and lupin covered islands and willows and poplars dominated the riparian stop-banks below Ohiti. Successive planting and eradication of exotic trees along the riparian margin (in particular berms) has resulted in decreased riparian health (MWH, 2011; Parrish, 1988). In approximately 30 years the riparian margin has changed from native vegetation to a relatively uniform vegetation community, consisting largely of willow (Salix spp.) (MWH, 2011). This switch to a homogenous community has changed the habitat provisions of the riparian and riverbed zones (MWH, 2011).
The spreading nature of exotic species such as willow and lupin, in the absence of control or eradication regimes, poses a risk to surrounding environments and habitats (MWH, 2011). For example, the spread of exotic vegetation into the gravel riverbed can eliminate potential riverbed bird habitat resulting in reduced native bird diversity (Parrish, 1988; Wagenhoff & Young, 2013). The effects of willow on native birds in braided river systems was highlighted in Wagenhoff & Young (2013). Willows were removed from a 1.5 – 2.5 km long section of the braided Tekapo River in 1992. Four bird species of conservation importance, including the banded dotterel (Charadrius bicinctus bicinctus), pied stilt (Himantopus himantopus leucocephalus), black-fronted tern (Chlidonias albostriatus), and South Island pied oystercatcher (Haematopus finschi), were observed using the newly cleared areas for nesting and foraging. Bird densities within the newly cleared section were similar to those in the reference habitat comprising bare shingle or sparse vegetation with grasses.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 9
Wagenhoff & Young (2013) summarised that in comparison to native riparian vegetation, willows:
i. Are likely to provide less suitable habitat for macroinvertebrates due to the dense willow roots and their ability to trap fine sediment
ii. May not sustain equally productive macroinvertebrate communities due to the shorter availability of leaf organic material during the year
iii. Can increase water temperature and epilithic biomass during the seasons when deciduous leaves are young or shed and hence provide less shade
iv. May degrade water quality by reducing levels of dissolved oxygen as a consequence of increased temperature or decomposition of large amounts of retained willow leaves
v. Can substantially reduce flow due to high evapotranspiration rates
vi. Retain lesser quantities of LWD (large woody debris) because light willow wood is prone to be carried downstream and decays quickly
vii. Trigger erosion, channel widening or migration if willows reduce channel capacity due to their extensive root growth
viii. Sustain less diverse native terrestrial arthropod and bird communities, amongst others.
(Wagenhoff & Young, 2013, pg. 22 - 23)
In summary, exotic vegetation persisting, and now dominating, the riparian margin of the Ngaruroro River is a direct function of plantings for control purposes. These plantings have modified the river ecosystem resulting in a homogeneous vegetation community and decreased habitat opportunities for native fauna species, including avifauna. The invasive, spreading, nature of willows and lupin poses a future risk to surrounding environments and habitats, especially in the absence of control or eradication regimes.
3.2.2 Riverbanks
The lower Ngaruroro River’s isolation from the Heretaunga Plains increases downstream due to stop-bank confinement (Hawke’s Bay Regional Council, 2011). Additionally, the stop-banking along the Ngaruroro has resulted in sections, particularly below Maraekakaho, to become a predominantly single channel, especially during periods of low flow (Hawke’s Bay Regional Council, 2011). This periodic transition into a single channel system has the potential to decrease the width of habitat used by avifauna (Parrish, 1988) and the fish fauna. Flood protection measures were discussed as far back as 1954, including plans to divert the Ngaruroro from its natural channel (Hawke’s Bay Catchment Board, 1954). These discussions lead to the Ngaruroro being diverted from Chesterhope (now the Clive River) to create a new river mouth in the Waitangi Estuary (Hawke’s Bay Catchment Board, 1954; Parrish, 1988). The diversion of the Ngaruroro was achieved through the creation of stop-banks to form a new straightened canal (Parrish, 1988).
10 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
The Ngaruroro River historically frequently migrated across the floodplain, creating extensive riverine wetland networks (MWH, 2011). However, these wetlands are becoming increasingly isolated, including some which are now considered palustrine wetlands (MWH, 2011). Wetlands are also frequently grazed on the rarely inundated Heretaunga Plains. Some of the remaining wetlands remain fed by tributary streams or groundwater springs rather than Ngaruroro River flood events.
3.2.3 Flow
MWH (2010a) have identified the expected mean annual low flow (MALF) to be 4,134 L/s in the Ngaruroro (at Fernhill); however, due to consented water abstraction the MALF is 3,517 L/s. Furthermore, the 7-day MALF suggests a larger disparity between the expected natural flow (5,240 L/s) and the current flow (4,396 L/s). This indicates the flow of Ngaruroro River is modified by human influences (water take). The Ngaruroro, aside from consented water takes, is regionally significant as a source of water during frequent droughts, and for providing water to the surrounding population for domestic purposes (MWH, 2010b). According to MWH (2010a) there were approximately 90 water abstraction consents in operation during the 2007/08 irrigation season. Pastoral farming, cropping, orchards, and vineyards are the land use types primarily associated with water abstractions affecting the Ngaruroro (MWH, 2010a). These land use types, in 2007/08, were responsible for the following water abstraction rates:
• Pastoral farming – 1,080 L/s
• Cropping – 1,063 L/s
• Orchard – 39 L/s
• Vineyard – 709 L/s
• Other – 601 L/s ‘Cropping’ and ‘other’ are dominated by the two largest water abstraction consents, the Glazebrooks (800 L/s) and the Artificial Recharge (600 L/s) operations. Based on the level of water abstraction along the lower Ngaruroro River, it is reasonable to say the flow rate is ‘managed’ (at least in the summer season) and, therefore, does not have a natural flow regime.
3.2.4 Gravel bed
The Hawke’s Bay region has traditionally been a source of high-quality riverbed gravel, with the majority extracted from the lower Ngaruroro River (Environmental Management Services Limited, 2016). The Ngaruroro is important as a gravel resource due to its accessibility and proximity to urban centres, and the suitability of the aggregate to a range of engineering purposes (Environmental Management Services Limited, 2016). The Heretaunga Plains is the source of approximately 300,000 m3 of riverbed gravel in the Hawke’s Bay region (approximately 400,000 m3 is currently sourced from the region). As a result, gravel extraction consents have been carefully managed to align with natural supply of gravel to the riverbed; however, demand remains high (Environmental Management Services Limited, 2016).
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 11
Gravel supply in the Hawke’s Bay rivers has been largely reliant on storm and flood events to entrain and transport gravels downstream (Environmental Management Services Limited, 2016; Hawke’s Bay Regional Council, 2017). However, gravel movement in the Ngaruroro has been limited to approximately 1.9 km of downstream movement in the last 40 years. Fewer storm/flood events in recent years has coincided with the spread of invasive weeds which further limits sediment and gravel movement. As a result, ‘beach raking’ (raking the gravel bed using a tractor and metal ripping blades) has been a widely used technique in flood scheme areas to encourage the downstream movement of gravel in the absence of gravel extraction operations (Environmental Management Services Limited, 2016; Hawke’s Bay Regional Council, 2017). This artificial manipulation of the Ngaruroro riverbed results in a modified system with an unnatural disturbance regime.
3.2.5 Braided pattern
The creation of stop-banks (Section 3.2.2), the modification of flow (Section 3.2.3), and manipulation of the gravel bed for extraction (Section 3.2.4) impact the braided nature of the Ngaruroro. For example, as detailed in Section 3.2.2, the river now flows in a single channel downstream of Mareakakaho. This coupled with the manipulation of the gravel bed for raking and extraction purposes suggests the braided nature of the Ngaruroro is no longer natural. Gravel raking can cause a decline in pool depth and abundance (MWH, 2011). This modification is acknowledged in ‘Revised Environmental Code of Practice for River Control and Drainage Works’ (Asset Management Group, 2003) where the importance of creating artificial deep pools and riffles to replicate the pre-existing form of the river after modification (beach raking/gravel extraction/etc.) is required. In summary, the braided nature of the Ngaruroro River is no longer in a natural state or pattern because of human influence and modification and that effect gets progressively more pronounced below Fern Hill.
12 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 2: Map of the lower Ngaruroro River, showing locations of modification as observed during the site visit. Captions for the inserted photos can be found in Table 2
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 13
Table 2: Captions for the images found in Figure 2. Photo Caption
A Willow establishment in the river channel causing semi-permanent islands.
B View of the river channel lined with exotic riparian and established willows within the gravel bed.
C Exotic seedlings taking root within the gravel bed.
D Exotic riparian margin, surrounding agricultural land use, and exotic seedlings in the gravel bed.
E Gravel extraction involving an excavator and dump truck driving across the gravel bed.
F Artificial stop-bank with livestock between the stop-bank and the exotic riparian margin.
G Gravel stockpiles within the river channel and evidence of vehicle tracks.
H Gravel stockpiles within the river channel, exotic riparian margin, and an artificial terrace created by vehicle movements.
I View from artificial stop-bank showing exotic riparian vegetation and previously grazed land.
J View of the artificially constructed river diversion where the river flows in a single, confined channel through to the Waitangi Estuary.
K Clive River – which is no longer connected to the Ngaruroro due to artificially diverting the Ngaruroro
14 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
4.0 Lower Ngaruroro River ecology
4.1 Water quality
For the below parameters, data from six monitoring sites along the Ngaruroro River have been used for water quality analyses (Table 3). The Kuripapango monitoring location is situated in the upper Ngaruroro River, and has been included in the analyses for comparison with the lower river. Whanawhana is located near the upstream extent of the lower Ngaruroro River. Water quality data has been presented in a downstream gradient order beginning, where applicable, with Kuripapango and ending with Chesterhope.
Table 3: Location of monitoring sites along the Ngaruroro River, including the upper Kuripapango site
Used in the water quality analyses. Included are the parameters where data were available. WT – water temperature (oC), DO – dissolved oxygen (mg/L), BD – black disk (m), NTU – turbidity (NTU), TN – total nitrogen (mg/L), TP – total phosphorus (mg/L), DIN – dissolved inorganic nitrogen, DRP – dissolved reactive phosphorus (µg/L), NO3 – nitrate
(µg/L), NO2 – nitrite (mg/L), NH4 – ammonium (µg/L), E. coli (MPN/100 mL). Sites have been ordered from upstream to downstream.
Monitoring Coordinates (NZ Map Grid) Parameters location Easting Northing Kuripapango WT, DO, BD, NTU, DRP, NO3, NH4, 2796945 6197400 (upper) pH, E. coli
WT, DO, BD, NTU, TN, TP, DIN, DRP, Whanawhana 2801974 6177384 NO3, NO2, pH, E. coli
WT, DO, BD, NTU, TN, TP, DIN, DRP, Ohiti 2827682 6170383 NO3, NO2, pH, E. coli
WT, DO, BD, NTU, TN, TP, DIN, DRP, Fernhill 2832921 6172987 NO3, NO2, pH, E. coli
WT, DO, BD, NTU, TN, TP, DIN, DRP, Motorway Bridge 2840708 6171611 NO3, NO2, pH, E. coli
WT, DO, BD, NTU, DRP, NO3, NH4, Chesterhope 2842492 6171513 pH, E. coli
Water quality is a very important habitat quality, as it directly affects the type and abundances of aquatic biota inhabiting the waterway. Whilst there are any number of elements affecting water quality, for the purpose of this report a select few ‘important’ ones have been used (and are those collected by regional and central government agencies). We have not, in this report, summarised or “boiled” down the various separate parameters into a “water quality” assessment but present the individual component data as separate habitat quality indicators and so also rank these separate parameters in testing “outstanding” rather than attempt to synthesise a water quality summary proxy. Below is a brief description of how these elements affect the aquatic ecology. Chronic effect levels can be found in Table 4.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 15
Water temperature2
Water temperature affects the oxygen carrying capacity of water which can have implications on the aquatic biota (as temperatures increase, oxygen concentrations decrease). This is due to the oxygen demands of many fish increasing as water temperatures increase due to heightened foraging activity. Furthermore, extreme water temperatures can restrict growth in aquatic biota due to increased stress and even kill or cause displacement.
Dissolved oxygen
Low dissolved oxygen concentrations can cause stress on aquatic biota, including the loss of keystone species at very low concentrations. Many organisms (especially sensitive taxa) will experience stress at dissolved oxygen concentrations between approximately 5 mg/L and 7.5 mg/L. Sustained stress can result in decreased abundances and the loss of some taxa. *
Water clarity
Water clarity can have implications for visual feeders (e.g. trout) and increased sedimentation. In reduced clarity, the foraging efficiency decreases as either more energy is spent to catch the same amount of prey, or food consumption decreases. Sustained high levels of turbidity can result in sedimentation infilling the interstitial spaces between substrates which can result in reduced availability of hyporheic habitat. **
Nutrients
Algal (periphyton) and aquatic plant growth relies on the supply of nitrogen (N) and phosphorus (P). These nutrients are often referred to as the ‘growth limiting’ nutrients as low concentrations can limit plant spread and biomass development. N and P uptake by plants relies on the availability of dissolved forms of these nutrients (dissolved inorganic nitrogen (DIN) and dissolved reactive phosphorus (DRP)). Total nitrogen (TN) and total phosphorus (TP) include forms of N and P which are not readily available for uptake by plants. Increased growth of algae or nuisance plants can negatively impact aquatic organisms by increasing sedimentation, reducing substrate migration, and diurnal fluctuations in dissolved oxygen as a result of respiration and photosynthesis. *, ** pH This indicates how acidic or alkaline the water is. A pH that is too high or too low may fail to support aquatic life; however, freshwater taxa have varying degrees of tolerance. Low pH (≤ 5) can restrict fish eggs from hatching and can result in localised extinction of sensitive and keystone species. Stress on most organisms occurs when pH is lower than 6.5 or greater than 9. * E. coli E. coli is a bacterium that generally originates in the faeces of warm blooded animals. It is a key indicator of drinkability and swimmability of a water body, as it is strongly linked to the presence of waterborne pathogens. It is less an ecological issue than a human use related issue.
2 For the purpose of this report, temperature has been included in the analysis of the ecology of the lower Ngaruroro River; however, has been excluded from comparisons with regional and national rivers as it is not a constituent of water quality, and can vary across New Zealand based on latitude, solar radiation, shade cover, etc.
16 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
*NIWA 2013 – National Objectives Framework – Temperature, Dissolved Oxygen & pH.
**HBRC 2016 – TANK SoE
Table 4: Chronic effects levels for water quality parameters with respect to maintaining quality freshwater communities. Chronic effects level
Temperature 21.5 oC d(lowland)
pH 7.42 – 8.01d or 6.5-8.0c
DO% 99.1 – 103.7 %d
DRP 0.01mg/L (FRP)c - 0.006 mg/Ld
Total Phosphate 0.033 mg/Lc
Ammonia 0.021 mg/Lc
Nitrite nitrogen 0.444 mg/Lc
Nitrate nitrogen Sensitive receiving – 1.0 mg/L; Moderately disturbed – 1.7 mg/L; Highly disturbed – 2.4-3.6 mg/La
Total Nitrogen 0.614 mg/Lc
E. coli 540 E. coli / 100mlb a – Hickey & Martin 2009. b – McBridge & Soller (NIWA) 2017. c – ANZECC 2000 - lowland river values d – Davies-Colley (NIWA) 2000
4.1.1 Water temperature
Water temperature recordings from the six monitoring sites indicates an increase in water temperature along a downstream gradient (Figure 3) with an appreciable increase of 5 0C between top and bottom. There is less observed change in water temperature between Ohiti and Chesterhope.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 17
Figure 3: Water temperature (oC) as measured at each monitoring site along the Ngaruroro River.
4.1.2 Dissolved oxygen
The dissolved oxygen concentration (mg/L) as recorded from the six monitoring locations do not show an obvious trend (Figure 4). The median dissolved oxygen concentration in the upstream Kuripapango monitoring site is similar to the median levels recorded at Chesterhope. Median dissolved oxygen concentrations are lowest at Ohiti.
Figure 4: Dissolved oxygen concentrations (mg/L) between the six monitoring locations along the Ngaruroro River.
18 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
4.1.3 Water clarity
Black disk measurements (m) have been collected at each of the six monitoring locations as a measure of water clarity (Figure 5). The median black disk measurement is highest in the upper Ngaruroro River (Kuripapango) compared with the lower river. The largest reduction in water clarity occurs between Whanawhana and Ohiti, with a continued decline from Ohiti downstream to Chesterhope.
Figure 5: Black disk measurements (m), as a measure of water clarity, as recorded at each monitoring location along the Ngaruroro River.
Turbidity (NTU) has been measured at each of the six monitoring locations and suggests, similar to black disk, that Kuripapango has “clean water” while Ohiti and Fernhill have highly variable and commonly poorer quality in terms of higher turbidity. The mean NTU at Whanawhana is considerably higher than the median NTU. This diparity suggests, while turbidity is predominantly low, there are occasions when NTU is very high (ignored as outliers in Figure 6). This is the same for all locations.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 19
Figure 6: Turbidity (NTU), as recorded at each monitoring location along the Ngaruroro River.
4.1.4 Nutrients
Total nitrogen
Total nitrogen (TN) concentrations have been recorded at four of the six monitoring locations along the Ngaruroro River (Figure 7). Total nitrogen data was unavailable from the Kuripapango monitoring location in the upper Ngaruroro River and Chesterhope. Median TN concentration increases by approximately 0.1 mg/L between Whanawhana and Ohiti. TN concentrations continue to increase downstream of Ohiti, although at a lesser rate.
Figure 7: Total nitrogen concentrations recorded at four of the monitoring locations along the Ngaruroro River.
Total phosphorus
20 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Total phosphorus (TP) concentrations increase between Whanawhana and Ohiti (Figure 8). However, the median concentration remains stationary between Ohiti and Fernhill, before slightly decreasing at the Motorway Bridge monitoring site. The mean TP concentrations at all locations is considerably higher than the median as a result of outliers which have not been included in Figure 8.
Figure 8: Total phosphorus concentrations recorded at four of the monitoring locations along the Ngaruroro River.
Dissolved Inorganic Nitrogen
As with TN and TP, median dissolved inorganic concentrations (DIN) increases considerably between Whanawhana and Ohiti (Figure 9). Median DIN concentrations remain relatively stable from Ohiti to the Motorway Bridge.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 21
Figure 9: Dissolved inorganic nitrogen concentrations recorded at four of the monitoring locations along the Ngaruroro River.
Dissolved Reactive Phosphorus
Dissolved reactive phosphorus (DRP) concentrations remain stable between the upper Kuripapango monitoring location and the Whanawhana site (Figure 10). Median DRP concentrations then increase along a downstream gradient through the lower Ngaruroro River.
Figure 10: Dissolved reactive phosphorus concentrations recorded at six monitoring locations along the Ngaruroro River.
Nitrate
22 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Nitrate (NO3) concentrations increase considerably between Whanawhana and Ohiti (Figure 11). Median nitrate concentrations remain relatively stable between Ohiti and the downstream Chesterhope site. Kuripapango, in the upper Ngaruroro River, has much lower concentrations of NO3 than the five monitoring locations in the lower Ngaruroro River.
Figure 11: Nitrate concentrations recorded at six monitoring locations along the Ngaruroro River.
Nitrite
Due to the low concentration of nitrite (NO2) in the lower Ngaruroro River (Figure 12) it is difficult to determine any possible trends along the river. However, the mean nitrite concentration at Whanawhana and the Motorway Bridge suggests these locations can encounter periods of relatively high concentrations compared to the two monitoring locations between these two sites.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 23
Figure 12: Nitrite concentrations recorded at six monitoring locations along the Ngaruroro River.
Ammonium
Ammonium (NH4) data was available at only two monitoring locations along the Ngaruroro River (Figure 13). However, it is evident ammonium levels increase between the upper Kuripapango and lower Chesterhope monitoring locations. This suggests NH4 increases in a downstream gradient.
Figure 13: Ammonium concentrations recorded at two monitoring locations along the Ngaruroro River.
24 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
4.1.5 pH
The pH of the water remains within an acceptable range throughout the Ngaruroro River (Figure 14) but does become noticeably more alkaline near the River mouth (Chesterhope).
Figure 14: pH recorded at six monitoring locations along the Ngaruroro River.
4.1.6 Bacteriological water quality
E. coli
E. coli concentrations (MPN/100 mL) increase in a downstream gradient (Figure 15). Whanawhana appears to have the lowest E. coli concentrations, compared to the downstream Chesterhope site which has the highest median E. coli concentrations. This is reflected in the higher mean value at Chesterhope, suggesting concentrations fluctuate considerably at this site.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 25
Figure 15: E. coli concentrations recorded at six monitoring locations along the Ngaruroro River.
4.2 Macroinvertebrates
Macroinvertebrate data were available for eight monitoring locations along the Ngaruroro River (Table 5). These macroinvertebrate data were converted into macroinvertebrate community index (MCI) scores to allow for comparison in community health. A single MCI score from the Kuripapango monitoring location in the upper Ngaruroro River is included for comparative purposes.
Table 5: Monitoring locations for the eight monitoring sites where macroinvertebrate data were available. Included are the years for which macroinvertebrate data were available. Monitoring location Coordinates (NZ Map Grid) Sampling occasions
Easting Northing
Kuripapango (upper) 2796945 6197400 2003
Upstream of Hawke’s Bay Dairies 2807908 6177557 2004, 2005, 2006, 2007, (U/S HB Dairies) 2008, 2009
Downstream of Hawke’s Bay 2817138 6172180 2005, 2006, 2007, 2008, Dairies (D/S HB Dairies) 2009, 2010
Ohiti 2827682 6170383 2003, 2005, 2006, 2007, 2008, 2009, 2010
Fernhill 2832921 6172987 2003, 2004, 2005, 2006, 2007, 2008, 2010
Carrick Road 2839026 6173411 2004, 2005, 2006, 2007, 2008, 2009
26 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Motorway Bridge 2840708 6171611 2004, 2005, 2006, 2007, 2008, 2009, 2010
Chesterhope 2842492 6171513 2003
Below are the descriptions of the macroinvertebrate indices used in this report. MCI The macroinvertebrate community index (MCI) indicates the proportion of invertebrates in the stream that are intolerant to pollution. Taxa are assigned a value based on its sensitivity, and these values are used to formulate the MCI (Stark, 1993) The formula for these calculations is:
MCI = (Sum of MCI Scores) x 20 / (Number of Taxa).
A stream that has a high MCI has a high proportion of sensitive taxa, and therefore likely has low levels of pollutants. Table 6 indicates expected MCI values for healthy to polluted streams (Stark & Maxted, 2004).
Table 6: MCI & QMCI score classification meanings (from Stark and Maxted 2004)
Quality Class Stark (1998) description MCI QMCI Excellent Clean >120 >6.0 Good Possible mild pollution 100-120 5-6 Fair Probable moderate pollution 80-100 4-5 Poor Probable severe pollution <80 <4
EPT As with the MCI, the EPT index is a measure of sensitive taxa within a stream. It is specifically a measure of the number of taxa that fall into three orders; Ephemoptera, Plectoptera, and Trichoptera (thus, EPT). Each of these orders are highly sensitive to stress, so the number of these taxa living in a waterbody is indicative of the ecosystems health.
4.2.1 MCI scores
Macroinvertebrate community data was used to calculate a range of macroinvertebrate community index (MCI) scores for six of the eight monitoring locations (only one MCI value was generated at Kuripapango and Chesterhope monitoring locations). There appears to be a gradual decline in MCI scores along a downstream gradient in the lower Ngaruroro River (Figure 16). However, the MCI scores generated at the upper Kuripapango and lowest-most Chesterhope site are very similar. Stark & Maxted (2007) state MCI scores between 100 – 119 indicate good water quality, and MCI scores between 80 – 99 suggest fair water quality. The median MCI score at all sites is between 100 – 119; however, the median score at Carrick Road is 100 suggesting this site has somewhere between fair and good water quality. On occasion, the lower monitoring locations return MCI values which are indicative of fair water quality.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 27
Figure 16: Macroinvertebrate community index (MCI) scores calculated from eight monitoring locations along the Ngaruroro River.
4.2.2 EPT taxa richness
Ephemoptera, Plectoptera, and Trichoptera (EPT) taxa richness appears to decrease along a downstream gradient (Figure 17). The median EPT taxa richness at the U/S HB Dairies site is the same as the upper quartile at the Motorway Bridge monitoring site.
28 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 17: EPT taxa richness from eight monitoring locations along the Ngaruroro River.
4.3 Fish biodiversity
The NIWA administered New Zealand Freshwater Fish Database (NZFFD) was used to determine fish taxa present in the lower Ngaruroro River. Due to discrepancies in fish recording methodologies, fish abundance has not been included. However, fish taxa presence has been reported, including the number of individual records on the NZFFD.
Furthermore, as this is an assessment of the mainstem of the lower Ngaruroro, fish records from tributaries and the upper river have been excluded from the below analyses.
4.3.1 Lower Ngaruroro River fish community
A search of the NIWA NZFFD showed records of 15 fish taxa present in the mainstem of the lower Ngaruroro River (Table 7). One taxa, Geotria australis, has a threatened – nationally vulnerable conservation status, while a further seven taxa have an at risk – declining conservation status. Two of the remaining taxa, Gambusia affinis and Oncorhynchus mykiss, are introduced and naturalised. According to NZFFDB torrentfish (Cheimarrichthys fosteri) and common bully (Gobiomorphus cotidianus) have been recorded on the most occasions (12 and 10 recorded observations, respectively). Dwarf galaxias (Galaxias divergens), inanga (G. maculatus), longfin eel (Anguilla dieffenbachia) and common smelt (Retropinna retropinna) were also common with nine observations. Koaro (G. brevipinnis) appears uncommon in this lower river system, being observed on one occasion.
No additional taxa were recorded in any tributaries feeding the lower Ngaruroro River (excluding the upper Ngaruroro and associated tributaries). However, bluegill bully (Gobiomorphus hubbsi), dwarf galaxias, koaro, and lamprey were only recorded in the mainstem of the lower Ngaruroro River. Longfin eel, shortfin eel (Anguilla australis), and common bully occurred in the most NZFFDB records from the lower Ngaruroro River catchment.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 29
Table 7: NIWA FFDB records of fish observed in the Ngaruroro mainstem between the Waitangi Estuary and Cableway Including their threat status. Marine wanderers and records of unidentified fish have been excluded.
No. Common name Scientific name Threat classification records Shortfin eel Anguilla australis Not threatened 8 Longfin eel Anguilla dieffenbachii At risk - declining 9 Torrentfish Cheimarrichthys fosteri At risk - declining 12 Koaro Galaxias brevipinnis At risk - declining 1 Dwarf galaxias Galaxias divergens At risk - declining 9 Inanga Galaxias maculatus At risk - declining 9 Gambusia Gambusia affinis Introduced and naturalised 3 Lamprey Geotria australis Threatened - nationally vulnerable 2 Crans bully Gobiomorphus basalis Not threatened 2 Common bully Gobiomorphus cotidianus Not threatened 10 Giant bully Gobiomorphus gobioides Not threatened 2 Bluegill bully Gobiomorphus hubbsi At risk - declining 3 Redfin bully Gobiomorphus huttoni At risk - declining 2 Rainbow trout Oncorhynchus mykiss Introduced and naturalised 4 Common smelt Retropinna retropinna Not threatened 9
4.4 Avifauna
The avifauna habitats of the Lower Ngaruroro River (between the Whanawhana cableway and the inland limit of the coastal marine area) include: riverbed (braided and single channel), riverine wetlands (within the immediate flood plain) and riparian forest, in bed and immediate flood plain scrub and grassland (pre-dominantly exotic) (MWH, 2011). These habitats provide feeding, roosting and nesting opportunities for avifauna species.
The highest value avifauna habitat type is braided riverbed. Braided riverbeds typically support an abundant and diverse assemblage of avifauna species (Parrish, 1988; Caruso 2006), including a number of Threatened and At Risk species, some of which are specialised to breed (Hughey et al 2012; Hawkes Bay biodiversity inventory 2014 doc) almost exclusively within this habitat type (Stephenson 2010). The braided river habitat of the Lower Ngaruroro River extends for approximately 50 km, from Whanawhana to Fernhill (WCO application) and is composed of approximately equal parts of torrent and braided sections. The braids are separated by a dynamic system of shingle beds and islands, some of which are vegetated but not uniformly so, with the upper reaches largely bare (Parrish, 1988). Although common in the South Island, braided river systems are rare in the North Island; the Ngaruroro River is described as the best and longest example of such a system within Hawke’s Bay (MWH, 2011) and this region has the highest cumulative area of braided riverbed habitat within the North Island (Caruso 2006).
The flood control reach (in which flood control activities are undertaken) extends for 11 km from Fernhill to the inland limit of the coastal marine area. The lowest 2 km are a single channel and are the most highly modified portion of the river. The avifauna community of single channel rivers generally consists of a variety of shags and ducks, with fewer Threatened or At Risk species than braided river habitat (Hughey et al 2012).
30 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Within and directly adjacent to the river are areas of wetland (riverine wetlands), including vegetated riparian wetlands and those formed within former river meanders (Stephenson 2010). The most notable riverine wetland along the reach is Pigsty Swamp; it is within an ox-bow and is described as “the only freshwater swamp of any significance on or near a river in Hawke’s Bay” (Parrish, 1988).
Along the reach there are also riparian forest, scrub and grassland habitats, which primarily consist of exotic vegetation (namely grass and willows) with pockets of native vegetation (Stephenson 2010).
Ngaruroro River Avifauna
The OSNZ atlas data provided a base list of 26 Threatened and At Risk avifauna species (Table 8), from a total of 79 taxa which potentially utilise habitats recorded within the seven 10 km x 10 km grid squares encompassing the wider Ngaruroro River area (refer to Figure 1 in Section 2.4 above for grid square locations). Twenty-three of these species were recorded during surveys of the Ngaruroro River and surrounds. New Zealand dotterel and shore plover, which were not with the OSNZ base list, were also observed during these surveys (Table 8). Eight species were excluded from further analyses as they either had not been recorded during surveys of the Lower Ngaruroro River (pied shag, Australian coot, and royal spoonbill) or primarily utilised habitats not included within this investigation (native forest (falcon) and coastal/estuarine areas (reef heron, shore plover, variable oystercatcher, white-fronted tern and New Zealand dotterel)). Thus, in total, 17 species were further investigated (see below) to determine whether the Ngaruroro River is a nationally outstanding habitat for these species (these results are summarised in Table 39).
For full base lists of the species identified within the OSNZ atlas and during surveys of the Ngaruroro River refer to Appendices 3 and 4. The assemblage of avifauna species recorded during surveys of the reach and the number of ‘more common’ Threatened and At Risk avifauna recorded historically are available in Appendices 5 and 6.
Table 8. Threatened and At Risk avifauna species identified within the OSNZ squares and recorded during surveys of the Ngaruroro River and surrounds.
SPECIES – Robertson et al. 2017 CONSERVATION STATUS – Robertson et al. 2017
OSNZ SQUARESOSNZ SURVEY RECORDS
Australasian Botaurus poiciloptilus Native Threatened Nationally Critical bittern Black-billed Larus bulleri Endemic Threatened Nationally Critical gull Grey duck Anas s. superciliosa Native Threatened Nationally Critical Shore plover Thinornis novaeseelandiae Endemic Threatened Nationally Critical x White heron Ardea modesta Native Threatened Nationally Critical Black-fronted Chlidonias albostriatus Endemic Threatened Nationally Endangered tern Reef Heron Egretta sacra sacra Native Threatened Nationally Endangered Banded Charadrius bicinctus bicinctus Endemic Threatened Nationally Vulnerable dotterel Caspian tern Hydroprogne caspia Native Threatened Nationally Vulnerable Pied shag Phalacrocorax varius varius Endemic Threatened Nationally Vulnerable x Wrybill Anarhynchus frontalis Endemic Threatened Nationally Vulnerable Marsh crake Porzana pusilla affinis Endemic At Risk Declining
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 31
New Zealand Anthus n. novaeseelandiae Native At Risk Declining pipit Red-billed gull Larus novaehollandiae scopulinus Native At Risk Declining South Island Haematopus finschi Endemic At Risk Declining pied oystercatcher Spotless crake Porzana t. tabuensis Native At Risk Declining White-fronted Sterna s. striata Native At Risk Declining tern Australasian Himantopus h. leucocephalus Native At Risk Recovering pied stilt New Zealand Poliocephalus rufopectus Endemic At Risk Recovering dabchick New Zealand Charadrius obscurus aquilonius Endemic At Risk Recovering x dotterel New Zealand Falco novaeseelandiae Endemic At Risk Recovering falcon Variable Haematopus unicolor Endemic At Risk Recovering oystercatcher Australian coot Fulica atra australis Native At Risk Naturally Uncommon x Black-fronted Charadrius melanops Native At Risk Naturally Uncommon dotterel Black shag Phalacrocorax carbo Native At Risk Naturally Uncommon novaehollandiae Little black Phalacrocorax sulcirostris Native At Risk Naturally Uncommon shag Royal spoonbill Platalea regia Native At Risk Naturally Uncommon
• Australasian bittern Australasian bitterns inhabit freshwater/wetland and utilise coastal/estuarine habitats. They are highly cryptic, are difficult to detect during surveys and inhabit areas that are difficult to survey (Barrie D. Heather & Robertson, 2000). As such, there is limited information on the abundance and distribution of bittern in New Zealand (O’Donnell & Robertson, 2016) and the national population estimate of 500-750 birds is likely to be an underestimate of the true population size. In 2009 a likely, but unconfirmed sighting of a bittern was recorded within a riparian zone at an ephemeral wetland along the Lower Ngaruroro River (Stephenson 2010) and in 1982 bittern were recorded at a number of nearby lake and wetland habitats. Being conservative and including the unconfirmed sighting, this approximately equates to 0.1-0.2 % of the national population of bittern that use the lower Ngaruroro River (using the likely underestimated population size); consequently, this reach is not considered to be nationally outstanding habitat for Australasian bittern.
• Black-billed gull Black-billed gulls breed mainly on braided riverbeds in the South Island, particularly rivers in Canterbury and North Otago (Maloney, Rebergen, Nilsson, & Wells, 1997). They overwinter in coastal/estuarine areas throughout New Zealand and some inhabit lakes in central North Island (B. Heather & Robertson, 2005). Their national population is approximately 15,000 birds (Stephenson 2010). 400-600 black-billed gulls have been recorded breeding near the Ngaruroro rivermouth, with a recent inland shift of the breeding colonies to an area near Mangatahi on the Lower Ngaruroro River. They are one of the most threatened species that breed on the Lower Ngaruroro River (Stephenson 2010 sources) and these breeding colonies represent approximately 2.7-4 % of the national black-billed population; as this is less than 5 % of the national population, the lower Ngaruroro River is not considered a nationally outstanding habitat for black-billed gulls.
32 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
• Grey duck Grey ducks are found primarily in wetland habitats (such as lakes, slow-flowing rivers and tidal water) and riparian margins throughout New Zealand. The main population strongholds include Waikato, Northland, Westland and around eastern Bay of Plenty/Gisborne (B. Heather & Robertson, 2005). Grey duck populations have been severely affected by hybridisation with mallard ducks (Anas platyrhynchos) and currently few, if any, pure populations of grey duck remain (Allendorf et al 2001). Without genetic analysis, it is near impossible to estimate the national population of grey duck. Between 7 and 23 ‘grey duck’ have been recorded on the Ngaruroro stream and associated tributaries during surveys between 1962 and 2009 (Maxwell et al., 1993; Parrish, 1988); Stephenson 2010). Due to a lack of credible grey duck population estimates, it cannot be determined whether the lower Ngaruroro River supports 5 % or more of the national grey duck population and whether it provides outstanding habitat for this species.
• White heron White herons inhabit freshwater and estuarine habitats and only breed on the Waitangiroto River near Okarito in Westland. The white heron national population is approximately 150-200 birds (B. Heather & Robertson, 2005). Each year at least one bird visits the lower reaches of the Ngaruroro River, its rivermouth, and Waitangi estuary (Stephenson 2010). This estimate is unspecific as is the location they inhabit when they are in the area; however as they are described as a rare winter visitor to Hawke’s Bay (Hawke’s Bay biodiversity inventory 2014 doc) it is unlikely that 5 % or more of the white heron population utilise the Lower Ngaruroro River at any one time; as such the lower Ngaruroro River is not considered nationally outstanding habitat for white heron.
• Black-fronted tern Black-fronted tern primarily breed on braided rivers in the South Island, with the largest populations in Canterbury and North Otago rivers (Maloney et al., 1997). Post-breeding, they migrate to coastal areas in the North and South Island. Hawke’s Bay is one of the sites regularly visited and at the Ngaruroro River specifically, 30-75 black-fronted tern regularly overwinter at or near the rivermouth (Stephenson 2010). Given that the national population is estimated to be approximately 5000 individuals (B. Heather & Robertson, 2005) this equates to 0.6-1.5 % of the population utilising the Lower Ngaruroro River. This is likely to be an overestimate given that it is not known how many of the 30-75 individuals use the Lower Ngaruroro River relative to the rivermouth (which is outside of the area being considered for the WCO application). Regardless, using this conservative approach, the lower Ngaruroro River is not considered to be outstanding habitat for black-fronted tern.
• Banded dotterel Banded dotterel breed in riverbed habitat throughout New Zealand, with their main breeding strongholds in Canterbury and Otago (Maloney et al., 1997). There is some uncertainty about the national population size, with a range of 25,000 – 50,000 birds reported (Dowding & Moore, 2006; B. Heather & Robertson, 2005; Pierce, 1999; Southey, 2009). Approximately 500 banded
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 33
dotterel breed on the braided riverbed habitat within the Lower Ngaruroro River, making them the second most common endemic breeding riverbed species of the Ngaruroro River (Stephenson 2010 sources). This population equates to approximately 1-2 % of the national banded dotterel population; therefore, the lower Ngaruroro River is not considered nationally outstanding for this species.
• Caspian tern Caspian terns typically inhabit coastal/estuarine habitats around New Zealand for breeding and foraging; however, small numbers of birds also forage in inland rivers and lakes around the lower North Island. Their national population size is estimated to be approximately 3,000 birds, (B. Heather & Robertson, 2005). Several pairs of Caspian terns have been observed around the Ngaruroro rivermouth, Waitangi Estuary and coastal area (Stephenson 2010); however, they have been rarely seen along the Lower Ngaruroro River. The number of records is not specified; however, given that they were rare, it can be concluded that the lower Ngaruroro River is not nationally outstanding habitat for Caspian tern.
• Wrybill Wrybills are primarily dependent on braided riverbed habitat (especially for breeding) and are considered a specialist for this habitat type. Their national population is approximately 4,500 – 5,500 individuals (Davies 1997 cited in Maloney et al 1997; Dowding & Moore, 2006; B. D. Heather & Robertson, 2000), with the largest populations found on rivers in North Otago and Canterbury (Maloney et al., 1997). Wrybill have been observed at the Waitangi estuary at the Ngaruroro rivermouth (albeit infrequently); however, to date, only one wrybill has been recorded on the Ngaruroro River itself during a 1986 survey (Stephenson 2010). This single record equates to 0.02% of the national population; therefore, the lower Ngaruroro River is not considered outstanding habitat for wrybill.
• Marsh crake Marsh crake are sparsely distributed throughout New Zealand and inhabit freshwater/wetland and coastal/estuarine habitats (B. Heather & Robertson, 2005). The national marsh crake population is approximately 5, 000 – 20,000 birds (H. A. Robertson et al., 2017). Given that marsh crake are included in a list of species that have been recorded rarely along the lower Ngaruroro River or may not be present currently (Stephenson 2010), it can be inferred that this reach is not nationally outstanding habitat for marsh crake.
• New Zealand pipit New Zealand pipit are widespread and locally abundant in open country habitat throughout a number of areas in New Zealand (B. Heather & Robertson, 2005). The national population is >100,000 individuals (H. A. Robertson et al., 2017). Stephenson (2010) recorded 24 pipits, mainly on the gravel riverbed flats, along the Ngaruroro River between Otamauri Stream and Mangatahi during work conducted in 2009; however, as only a section of the Lower Ngaruroro
34 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
River was surveyed. Due to limited surveying, this record is likely to be an underestimate of the number of pipit that use this reach; therefore, the percentage of the national population that utilises the lower Ngaruroro River cannot be calculated. However, 5,000 pipit would need to be using this reach for the 5% national significance threshold to be reached (assuming a national population of 100,000 birds). An extrapolation of 24 birds to estimate the population along the entire reach would reach 5,000 individuals; therefore, the lower Ngaruroro River is not considered outstanding habitat for New Zealand pipit.
• Red-billed gull Red-billed gulls inhabit coastal/estuarine, freshwater and farmland/open country habitats. They are described as widespread and locally common in New Zealand (B. Heather & Robertson, 2005) and their national population is >100,000 birds (H. A. Robertson et al., 2017). Red-billed gulls mainly use the Ngaruroro rivermouth (some breed there) and estuarine habitats; however, an unspecified number of birds have also been observed along the lower Ngaruroro River. Given red-billed gulls primarily use areas outside of that being considered in the WCO application, it can be inferred that the lower Ngaruroro River does not provide nationally outstanding habitat for red-billed gulls.
• South Island Pied Oystercatcher (SIPO) South Island pied oystercatchers are primarily dependent on braided rivers for nesting habitat, with the largest populations found in North Otago and Canterbury rivers (Maloney et al., 1997). Most SIPO migrate to the North Island or northern areas of the South Island after breeding and overwinter in estuarine/coastal habitats. Surveys of the lower Ngaruroro River have indicated that up to 10 SIPO utilise this area including as breeding habitat, making it one of only two areas in the North Island that SIPO have been recorded breeding (Stephenson 2010). Given that the national SIPO population is approximately 90,000 - 130,000 birds (Dowding & Moore, 2006; Southey, 2009), the number of birds using the lower Ngaruroro River, represent 0.008 – 0.01% of the national population. Consequently, the lower Ngaruroro River is not considered to be nationally outstanding habitat for SIPO.
• Spotless crake Spotless crake inhabit freshwater/wetland and coastal/estuarine habitats, with stronghold populations in northern North Island and in the Manawatu/Horowhenua dune lakes (B. Heather & Robertson, 2005). The national population of spotless crake is approximately 5, 000 – 20,000 individuals (H. A. Robertson et al., 2017). A low but unspecified number of spotless crake have been recorded in Pigsty Swamp and at the Ngaruroro rivermouth (Parrish, 1988); however, it is unlikely that this local population exceeds the 5% nationally outstanding criterion (i.e. 250 – 1,000 birds using the above national population estimate). If the lower Ngaruroro River population were close to the 5% threshold, more birds would most likely have been encountered during surveys of the reach. Consequently, the lower Ngaruroro River is not considered nationally outstanding for spotless crake.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 35
• Australasian pied stilt Australasian pied stilts inhabit freshwater, farmland/open country and coastal/estuarine habitats and breed throughout most of New Zealand (B. Heather & Robertson, 2005). Their national population is approximately 30,000 birds (Dowding & Moore, 2006; B. Heather & Robertson, 2005). Pied stilt are the third most numerous species surveyed along the Ngaruroro River and have been observed breeding on the braided riverbed and foraging in pools, riffles and channel edges (Stephenson 2010). Between 1962 and 1993, 173 – 461 pied stilt were observed during surveys conducted along the reach (Maxwell et al., 1993; Parrish, 1988, Adams 1993 in Stephenson 2010). Furthermore, during 2009 Stephenson (2010) counted 125 birds between Otamauri Stream and Mangatahi. These numbers indicate that approximately 0.6 - 1.5% of the national population utilise this reach. Consequently, the Ngaruroro River does not provide nationally outstanding habitat for pied stilt.
• New Zealand dabchick New Zealand dabchick are widely distributed in the North Island and primarily inhabit freshwater lakes. Their national population is approximately 1,700 birds (B. Heather & Robertson, 2005). An unspecified number of dabchick were recorded on Pigsty wetland in 1982 (K. Todd pers. comm. in Parrish, 1988); no other sightings have since been recorded. Dabchick, have been recorded in a number of nearby lakes (such as Lake Oingo and Lake Runanga) (Stephenson 2010); however, these areas are not considered within the WCO application as they are not lacustrine wetlands (i.e. directly associated with the Ngaruroro River). Given that the number of dabchick observed during the 1982 sighting was not recorded, the proportion of the national population that this represents cannot be calculated; however, as dabchick have not been sighted since along the reach it can be deemed that the reach does not provide nationally outstanding habitat for New Zealand dabchick.
• Black-fronted dotterel Black-fronted dotterel utilise freshwater and coastal/estuarine habitats (B. Heather & Robertson, 2005) and are primarily dependent on braided riverbeds for nesting (Maloney et al., 1997). Their national population is estimated to be approximately 2000 birds, with population strongholds in Hawke’s Bay, Wairarapa and Manawatu (Dowding & Moore, 2006; B. D. Heather & Robertson, 2015). 39 – 145 black-fronted dotterel were observed during surveys of the Ngaruroro River between 1962 and 1993. This population is thought to have reached carrying capacity as similar numbers were recorded during the latter surveys (Maxwell et al., 1993; Parrish, 1988) as well as during survey work conducted by Stephenson (2010) in 2009. The number of birds using the Lower Ngaruroro River represents approximately 1.95 - 7.25% of the national population. Given that the number of black-fronted dotterels using this habitat appears to have stabilised towards the higher end of this range (i.e. >5%), on a national scale, the lower Ngaruroro River is considered to be outstanding habitat for black-fronted dotterel. It must be noted that, in general, the scientific literature on black-fronted dotterels is reasonably sparse and populations have not been surveyed extensively and/or recently throughout New Zealand, so the national population estimate may not reflect the true population size; the estimate however gives an indication based on what is currently known and gives an indication of the significance of the Ngaruroro River population on a national scale.
36 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
• Black shag Black shags inhabit coastal/estuarine and freshwater areas throughout New Zealand. Their national population is approximately 10,000 – 20,000 birds (B. Heather & Robertson, 2005). 3 – 18 black shags have been sighted between 1962 and 1993 during surveys conducted along the Ngaruroro River (Maxwell et al., 1993; Parrish, 1988). There are no recent survey data for black shags in this reach, however assuming that a similar number of birds still use the Ngaruroro River, this represents <0.2% of the national population. Consequently, the Lower Ngaruroro River is not considered a nationally outstanding reach for black shag.
• Little black shag Little black shags inhabit freshwater and coastal/estuarine areas. They breed at a number of locations in the North Island, with large colonies in Auckland, Lake Wairarapa, Waikato, Rotorua Lakes, Hawke’s Bay and Lake Taupo. Their national population is approximately 2,000 – 10,000 birds (B. Heather & Robertson, 2005). 0 – 16 little black shags were recorded in surveys conducted along the Ngaruroro River between 1962 and 1993 (Maxwell et al., 1993; Parrish, 1988); however, there are no recent data for little black shags for this reach. Assuming that a similar number of birds still use the Ngaruroro River, using a conservative approach, this represents 0.8 – 2% of the national population; therefore, the Ngaruroro River is not considered a nationally outstanding reach for little black shag.
Habitat condition and value summary statement
The lower Ngaruroro River contains a diversity of avifauna habitats including: riverbed (single and braided), wetlands (riverine), riffles/rapids, backwaters, seeps, exotic grassland/herbfield, and exotic forest and scrub (Parrish 1988 and Ngaruroro Flood Protection EMP).
The braided riverbed is the highest value avifauna habitat of the lower Ngaruroro River and is utilised by a diverse assemblage of species (Stephenson 2010). This habitat is described as the “best and largest example of a braided river system in Hawke’s Bay” and may be the “largest single area of braided riverbed habitat in the North Island” (Stephenson 2010). Despite this, the condition of the braided riverbed is highly modified and the habitat could be improved. Some areas are becoming “choked” by the encroachment of exotic vegetation which reduces the area of braided habitat and, in turn, reduces avifauna nesting and foraging habitat. Similarly, gravel extraction and beach raking in the lower reach, reduces riverbed habitat and increases avifauna disturbance (Stephenson 2010).
Wetland habitats are not common along the lower Ngaruroro River and surveys of the reach have recorded very low abundances of wetland birds. The highest value wetland habitats include Pigsty Swamp and a wetland area near Matapiro Road; however, similar to the braided riverbed habitat, exotic weeds are dominant (Ngaruroro flood protection EMP, Stephenson 2010), reducing the quality of these wetlands.
The riparian zone of the upstream extent of the Lower Ngaruroro River consists of regenerating native forest; however, there is a gradient of decreasing abundance of native vegetation as you head downstream. The riparian zone within the Hawke’s Bay Regional Council’s flood control scheme (36 km from Mangatahi to the rivermouth) is dominated by exotic vegetation including
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 37
willows, poplars, tree lupins, exotic grasses and shrubs, with only small pockets of native vegetation (Ngaruroro flood protection EMP).
The 2 km downstream most extent of the Lower Ngaruroro River is a highly modified channel (Parrish 1988, Stephenson 2010, Ngaruroro flood protection EMP). This reach is inhabited by a variety of avifauna species, but very few Threatened or At Risk species.
In summary, the Lower Ngaruroro River contains a diversity of habitats, however in general their potential, in terms of habitat quality, is not being fulfilled. This is due to the dominance of exotic vegetation, weed infestations and channel modification. In some areas the size of available avifauna habitat is also being reduced due to gravel extraction and beach raking (these activities also disturb avifauna). The Lower Ngaruroro River does support a variety of avifauna species, including Threatened and At Risk species, however if weeds are not controlled (especially in braided riverbed habitat), over time, nesting and foraging habitats may reduce in size and in turn the richness and abundance of avifauna may decrease.
4.5 Ngaruroro Ecology Summary
Generally, the ecological condition of the lower Ngaruroro River becomes increasingly degraded towards the outlet to the Waitangi Estuary. For example, nutrients and E. coli concentrations increase along a downstream gradient, whilst water clarity decreases. Dissolved oxygen remains relatively stable throughout the lower Ngaruroro River. This general trend was replicated in the macroinvertebrate community which, apart from slight fluctuations, appears to be in a poorer condition closer to the Waitangi Estuary. The mean and median macroinvertebrate community index (MCI) scores for all monitoring locations were suggestive of good water quality; however, there were increased instances of individual MCI scores being indicative of fair water quality at the downstream monitoring locations. Thirteen native fish have been recorded as present in the main stem of the lower Ngaruroro River, of which eight have a conservation threat status, seven are considered “at risk – declining” and one is threatened (with extinction) – i.e. “nationally vulnerable” (Lamprey). While this suggests the lower Ngaruroro River could be important for the habitat it provides to a range of threatened and at risk taxa in New Zealand, it should be noted that these species are relatively common and abundant throughout most large New Zealand rivers. This metric is explored further in Section 7.0.
38 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
5.0 Hawkes Bay rivers - Regional ecological comparison
NIWA data was used to compare water quality, macroinvertebrates, and fish assemblages between the Ngaruroro River and Hawkes Bay State of the Environment (SoE) rivers (Table 9). The Ngaruroro River has the fourth largest catchment of these rivers, and contains the most monitoring locations.
Table 9: Rivers included in the State of the Environment monitoring and reporting by the Hawkes Bay Regional Council, including their catchment size and no of locations where datasets are available from NIWA. River Catchment (ha) No. data locations Aropaoanui river 16,809 1 Esk River 26,785.5 2 Waikari River 32,495 1 Clive river 51,462 1 Tutaekuri River 81,827 2 Porangahau River 84,971 1 Ngaruroro River 202,200 6 Mohaka River 244,000 5 Tukituki River 249,408 3 Wairoa River 367,032 2
Available data from monitoring sites in the upper portions of these rivers have been removed from the below comparisons and analyses to ensure like-for-like comparisons can be made. Furthermore, in some cases outliers have been removed from the box plots for readability purposes.
5.1 Water quality
Water quality data have been collected from a range of monitoring locations on each of the SoE rivers outlined in Table 9. Water temperature has not been included for comparison between the Hawkes Bay rivers as it is considered to hold little importance when comparing water quality across a number of rivers subjected to varying climatic conditions. The coordinates of all monitoring locations on the rivers included in section 4 can be found in Appendix 7. Unless otherwise stated, the order of rivers found in the following tables and figures has been determined by ranking the median value. Ammonium has not been included in the below analyses as data availability was limited to three rivers.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 39
5.1.1 Dissolved oxygen
Of the ten Hawkes Bay rivers included in this analysis, the lower Ngaruroro River ranks fifth in mean and median dissolved oxygen (mg/L) concentrations (Figure 18; Table 10). The Tukituki River and Mohaka River had considerably higher dissolved oxygen concentrations, followed by the Esk River, Waikari River, and Ngaruroro River which all had relatively similar dissolved oxygen concentrations. The Clive River, which neighbours Ngaruroro River had the lowest dissolved oxygen concentrations by a considerable margin.
Figure 18: Dissolved oxygen (mg/L) concentrations in 10 rivers in the Hawkes Bay region.
Table 10: Descriptive statistics for dissolved oxygen in 10 Hawkes Bay rivers, including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification.
Standard Standard Sample Rank by Rank by River Mean Error Median Deviation Variance mean median Tukituki River 10.95 0.07 10.85 1.85 3.43 1 1 Mohaka River 10.80 0.05 10.76 1.23 1.52 2 2 Esk River 10.33 0.09 10.25 1.43 2.05 3 3 Waikari River 10.31 0.27 10.22 1.74 3.04 4 4 Ngaruroro River 10.27 0.06 10.21 1.27 1.61 5 5 Aropaoanui river 9.98 0.16 9.92 1.38 1.91 6 6 Porangahau River 9.61 0.19 9.92 1.65 2.71 8 7 Tutaekuri River 9.88 0.21 9.89 1.79 3.19 7 8 Wairoa River 8.90 0.19 8.80 1.90 3.60 9 9 Clive river 7.99 0.15 8.00 1.87 3.50 10 10
5.1.2 Water clarity
Black disk (m) measurements were greatest (by 40 cm) in the Tutaekuri River (Figure 19; Table 11). Only 13 centimetres separated the second ranked median water clarity in Aropaoanui River
40 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
(1.9 m) and the sixth ranked Esk River (1.78 m). The Ngaruroro River ranked seventh for median water clarity; however, ranked fifth for mean water clarity.
Figure 19: Black disk measurements (m) in 10 rivers in the Hawke’s Bay region.
Table 11: Descriptive statistics for black disk water clarity in 10 Hawke’s Bay rivers. Including ranking the rivers according to mean and median black disk measurements. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Tutaekuri River 2.46 0.24 2.30 1.80 3.23 1 1 Aropaoanui river 2.05 0.14 1.90 1.16 1.35 2 2 Waikari River 1.77 0.14 1.87 0.89 0.79 6 3 Clive river 1.69 0.16 1.85 0.77 0.59 7 4 Tukituki River 2.04 0.07 1.80 1.64 2.68 3 5 Esk River 2.01 0.10 1.78 1.23 1.52 4 6 Ngaruroro River 1.81 0.08 1.31 1.69 2.86 5 7 Mohaka River 1.53 0.05 1.20 1.38 1.89 8 8 Porangahau River 1.35 0.15 1.19 1.16 1.34 9 9 Wairoa River 0.98 0.37 0.60 1.92 3.69 10 10
The ranking of the Hawke’s Bay rivers according to median turbidity (NTU) confirmed Ngaruroro River ranks poorly for water clarity and turbidity amongst the Hawke’s Bay rivers (Figure 20; Table 12). However, it is worth noting Waikari River ranks very poorly (9th) by mean, yet favourably by median (1st).
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 41
Figure 20: Turbidity recordings (NTU) in 10 rivers in the Hawke’s Bay region.
Table 12: Descriptive statistics for turbidity (NTU) in 10 Hawke’s Bay rivers Including ranking the rivers according to mean and median turbidity. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Waikari River 55.78 52.42 1.51 314.49 98,906.15 9 1 Esk River 4.96 0.99 1.65 15.62 244.01 1 2 Aropaoanui river 6.09 2.34 1.65 19.30 372.56 2 3 Tutaekuri River 13.66 6.43 1.70 53.42 2,853.87 4 4 Tukituki River 19.99 3.77 1.70 102.37 10,479.00 7 5 Clive river 6.14 2.50 2.00 31.49 991.41 3 6 Mohaka River 15.17 1.63 2.50 43.91 1,928.09 5 7 Ngaruroro River 18.58 2.70 2.80 63.51 4,033.34 6 8 Porangahau River 48.13 15.42 4.70 128.07 16,401.72 8 9 Wairoa River 67.51 19.72 14.00 225.69 50,934.97 10 10
5.1.3 Nutrients
Total nitrogen (TN) The Ngaruroro appears to have the lowest median TN concentrations amongst the SoE rivers in the Hawke’s Bay region (Figure 21; Table 13). This is in comparison to the neighbouring Clive River which has the highest median TN concentrations.
42 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 21: Total nitrogen (TN; mg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 13: Descriptive statistics for total nitrogen (TN; mg/L) concentrations in 10 Hawke’s Bay rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Ngaruroro River 0.33 0.03 0.24 0.48 0.23 2 1 Mohaka River 0.32 0.02 0.28 0.21 0.04 1 2 Tutaekuri River 0.39 0.05 0.32 0.37 0.14 4 3 Wairoa River 0.58 0.09 0.33 0.83 0.69 6 4 Aropaoanui river 0.38 0.04 0.36 0.28 0.08 3 5 Esk River 0.47 0.03 0.42 0.26 0.07 5 6 Porangahau River 0.66 0.07 0.47 0.47 0.22 7 7 Waikari River 0.69 0.13 0.49 0.81 0.65 8 8 Tukituki River 0.82 0.04 0.65 0.65 0.42 9 9 Clive river 1.27 0.28 0.72 2.05 4.22 10 10
Total phosphorus (TP) The Ngaruroro also ranks favourably for median TP concentrations in the Hawke’s Bay region (Figure 22; Table 14). However, the Tukituki also has a median TP concentration of 0.01 mg/L. As with TN, the Clive has the highest mean and median TP concentration by a considerable margin.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 43
Figure 22: Total phosphorus (TP; mg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 14: Descriptive statistics for total phosphorus (TP; mg/L) concentrations in 10 Hawke’s Bay rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Ngaruroro River 0.03 0.01 0.01 0.11 0.01 1 1= Tukituki River 0.04 0.01 0.01 0.10 0.01 4 1= Esk River 0.03 0.00 0.02 0.06 0.00 2 3= Mohaka River 0.04 0.01 0.02 0.09 0.01 5 3= Tutaekuri River 0.04 0.01 0.02 0.08 0.01 6 3= Porangahau River 0.05 0.01 0.02 0.07 0.01 7 3= Aropaoanui river 0.03 0.00 0.03 0.04 0.00 3 7= Waikari River 0.07 0.04 0.03 0.24 0.06 8 7= Wairoa River 0.09 0.02 0.03 0.24 0.06 9 7= Clive river 0.15 0.03 0.11 0.34 0.11 10 10
Dissolved inorganic nitrogen (DIN) The mean DIN concentrations were the lowest in the Ngaruroro; however, median concentrations ranked third (Figure 23; Table 15). The Ngaruroro had the smallest range of DIN concentrations, suggesting DIN does not fluctuate as much as it does in other Hawke’s Bay rivers.
44 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 23: Dissolved inorganic nitrogen (DIN; mg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 15: Descriptive statistics for dissolved inorganic nitrogen (DIN; mg/L) concentrations in 10 Hawke’s Bay rivers. Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Aropaoanui river 0.15 0.02 0.07 0.15 0.02 3 1= Porangahau River 0.16 0.03 0.07 0.21 0.05 4 1= Ngaruroro River 0.11 0.01 0.08 0.11 0.01 1 3 Wairoa River 0.21 0.04 0.11 0.39 0.15 5 4 Mohaka River 0.15 0.01 0.14 0.09 0.01 2 5 Tutaekuri River 0.21 0.03 0.15 0.25 0.06 6 6 Waikari River 0.27 0.04 0.22 0.25 0.06 7 7 Esk River 0.28 0.01 0.27 0.14 0.02 8 8 Clive river 0.57 0.07 0.43 0.48 0.23 9 9 Tukituki River 0.62 0.04 0.44 0.57 0.33 10 10
Dissolved reactive phosphorus (DRP) The Porangahau has the lowest median DRP concentrations (2 µg/L), followed by the Ngaruroro on 5 µg/L (Figure 24; Table 16). Clive River had the highest mean and median concentrations, including the largest range in values.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 45
Figure 24: Dissolved reactive phosphorus (DRP; mg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 16: Descriptive statistics for dissolved reactive phosphorus (DRP; mg/L) concentrations in 10 Hawke’s Bay rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Porangahau River 6.61 1.05 2.00 9.12 83.13 2 1 Ngaruroro River 5.75 0.22 5.00 5.23 27.36 1 2 Wairoa River 16.27 5.26 6.00 62.27 3,877.63 9 3 Tukituki River 12.84 1.54 6.72 38.34 1,469.93 4 4 Mohaka River 7.47 0.17 7.00 4.64 21.51 3 5 Tutaekuri River 14.58 1.37 13.00 11.80 139.29 5 6 Aropaoanui river 15.28 1.36 14.00 11.65 135.71 7 7 Esk River 15.89 1.10 14.00 17.87 319.48 8 8 Waikari River 15.27 1.79 14.50 11.57 133.89 6 9 Clive river 67.72 2.78 67.00 36.38 1,323.21 10 10
Nitrate (NO3) The Ngaruroro has the lowest mean nitrate concentrations; however, ranks third for median concentrations (Figure 25; Table 17). The Clive and Tukituki rivers had the highest nitrate concentrations by a considerable margin.
46 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 25: Nitrate (NO3; µg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 17: Descriptive statistics for nitrate (NO3; µg/L) concentrations in 10 Hawke’s Bay rivers. Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Porangahau River 158.52 18.85 40.00 209.06 43,705.51 5 1 Wairoa River 126.40 23.03 56.50 349.25 121,977.82 2 2 Ngaruroro River 95.75 3.51 69.22 98.51 9,705.11 1 3 Aropaoanui river 144.24 14.03 77.00 155.59 24,207.82 4 4 Tutaekuri River 170.38 14.28 126.50 161.57 26,106.34 6 5 Mohaka River 142.88 3.01 138.89 89.22 7,959.56 3 6 Waikari River 234.64 25.31 187.00 232.01 53,828.01 7 7 Esk River 287.25 35.69 227.00 679.95 462,328.39 8 8 Clive river 543.89 32.70 410.00 481.65 231,988.59 9 9 Tukituki River 606.54 18.03 489.00 544.22 296,178.88 10 10
Nitrite (NO2) Nitrite concentrations in many of the Hawke’s Bay rivers were very low, suggesting the differences between the rivers are marginal (Figure 26; Table 18). However, it was evident nitrite concentrations were highest in Clive River.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 47
Figure 26: Nitrate (NO2; µg/L) concentrations in 10 rivers in the Hawke’s Bay region.
Table 18: Descriptive statistics for nitrate (NO2; µg/L) concentrations in 10 Hawke’s Bay rivers.
Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Note: numbers have been rounded to nearest 3 decimal places; however, rivers are ordered according to 4 decimal places.
Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Ngaruroro 0.002 0.000 0.001 0.004 0.000 2 1 Mohaka River 0.002 0.000 0.002 0.001 0.000 1 2 Tutaekuri River 0.003 0.000 0.003 0.002 0.000 3 3= Aropaoanui river 0.003 0.000 0.003 0.002 0.000 4 3= Porangahau River 0.003 0.000 0.003 0.003 0.000 6 3= Wairoa River 0.004 0.000 0.003 0.005 0.000 7 3= Esk River 0.003 0.000 0.003 0.002 0.000 5 7= Tukituki River 0.004 0.000 0.003 0.003 0.000 8 7= Waikari River 0.007 0.002 0.006 0.012 0.000 9 9 Clive river 0.014 0.002 0.010 0.010 0.000 10 10
5.1.4 Bacteriological water quality
E. coli concentrations where lowest in the Tutaekuri (median) and Esk River (mean) amongst the Hawke’s Bay rivers (Figure 27; Table 19). Ngaruroro River ranked sixth for mean and fourth for median E. coli levels. Wairoa and Waikari Rivers had means which were considerably higher than the median levels suggesting E. coli concentrations fluctuate and can get very high.
48 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 27: E. coli (MPN/100 mL) concentrations in 10 rivers in the Hawke’s Bay region.
Table 19: Descriptive statistics for E. coli (MPN/100 mL) concentrations in 10 Hawke’s Bay rivers. Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification Rank Rank Standard Standard Sample by by River Mean Error Median Deviation Variance mean median Tutaekuri River 111.73 79.70 11.00 390.45 152,448.22 3 1 Mohaka River 129.04 56.07 14.80 909.29 826,813.52 4 2 Esk River 74.76 38.35 16.50 271.21 73,554.58 1 3 Ngaruroro 163.38 69.96 17.00 986.97 974,109.10 6 4 Tukituki River 141.97 21.69 24.00 507.69 257,753.93 5 5 Wairoa River 649.21 403.31 34.00 2,705.48 7,319,605.40 9 6= Waikari River 720.70 637.08 34.00 3,185.39 10,146,733.21 10 6= Aropaoanui river 201.60 125.50 34.50 639.90 409,474.84 7 8 Porangahau River 105.63 38.64 44.50 197.05 38,828.51 2 9 Clive river 225.25 82.52 105.00 420.79 177,065.99 8 10
5.1.5 Regional water quality results
Accounting for all water quality parameters assessed above, the lower Ngaruroro River does not provide for regionally outstanding water quality when compared against the lower section of nine other Hawke’s Bay rivers (Table 20). However, the lower Ngaruroro does have regionally outstanding low mean levels of dissolved nitrogen and phosphorus. These low levels suggest algal and plant growth would be limited. Dissolved oxygen concentration, water clarity, and E. coli do not rank as regionally outstanding.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 49
Table 20: Mean and median water quality results of the lower Ngaruroro River when compared against the lower sections of nine other Hawke’s Bay rivers.
Regional rank
Parameter Mean Median Regionally outstanding?
Dissolved oxygen 5/10 5/10 No
Black disk 5/10 7/10 No
Turbidity* 6/10 8/10 No
Total nitrogen* 2/10 1/10 Yes (median)
Total phosphorus* 1/10 1=/10 Yes (mean and median)
Dissolved inorganic nitrogen* 1/10 3/10 Yes (mean)
Dissolved reactive phosphorus* 1/10 2/10 Yes (mean)
Nitrate* 1/10 3/10 Yes (mean)
Nitrite* 2/10 1/10 Yes (median)
E. coli* 6/10 4/10 No
Average rank 3/10 3.5/10 No
5.2 Macroinvertebrates
Detailed macroinvertebrate data availability was limited to eight of the State of the Environment (SoE) rivers in the Hawke’s Bay. Therefore, Wairoa River and Clive River have been excluded from the macroinvertebrate analyses.
5.2.1 MCI scores
Of the rivers where detailed macroinvertebrate data was available, the Ngaruroro ranked second (Figure 28; Table 21). Four of the rivers had mean and median MCI scores which were indicative of good water quality, according to Stark & Maxted (2007). However, the MCI score for Aropaoanui River (mean = 101.67; median = 100) are close to the boundary between good and fair water quality (good = MCI scores 100 – 119; fair = 80 – 99). The remaining rivers scores were suggestive of fair water quality. The lower quartile for Porangahau River is below 80 which is indicative of poor water quality.
50 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 28: Macroinvertebrate community index (MCI) scores for eight of the ten SoE rivers in the Hawke’s Bay region.
Table 21: Descriptive statistics for macroinvertebrate community index (MCI) scores in eight of the ten Hawke’s Bay rivers. Including ranking the rivers according to mean and median MCI score. Ngaruroro River has been highlighted in red to allow for easy identification Standard Standard Sample Rank of Rank of River Mean Error Median Deviation Variance mean median Esk River 111.08 2.23 110.54 8.35 69.78 1 1 Ngaruroro River 106.71 1.28 106.67 8.80 77.48 3 2 Mohaka River 107.18 2.45 105.70 9.81 96.31 2 3 Aropaoanui River 101.67 4.17 100.00 11.05 122.00 4 4 Waikari River 99.05 3.77 96.67 10.67 113.80 5 5 Tutaekuri River 94.30 3.30 91.13 9.32 86.93 6 6 Tukituki River 94.20 2.91 90.00 16.23 263.30 7 7 Porangahau River 82.22 4.11 86.09 10.87 118.12 8 8
5.2.2 EPT taxa richness
The lower Ngaruroro River had a mean and median EPT taxa richness of 6.17 and 6, respectively, meaning it ranked fifth highest out of the Hawke’s Bay rivers (Figure 29; Table 22). As with MCI, the Esk had the highest EPT taxa richness, whilst the Porangahau had the lowest.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 51
Figure 29: EPT taxa richness for eight of the ten SoE rivers in the Hawke’s Bay region.
Table 22: Descriptive statistics for EPT taxa richness in eight of the ten Hawke’s Bay rivers Including ranking the rivers according to mean and median richness. Ngaruroro River has been highlighted in red to allow for easy identification Standard Standard Sample Rank of Rank of River Mean Median Error Deviation Variance mean median Esk River 9.07 0.74 9.50 2.79 7.76 1 1 Waikari River 8.63 0.80 8.50 2.26 5.13 2 2 Aropaoanui River 7.38 0.86 7.50 2.45 5.98 3 3 Mohaka River 7.13 0.59 7.00 2.36 5.58 4 4 Ngaruroro River 6.17 0.34 6.00 2.17 4.70 5 5 Tukituki River 5.61 0.60 5.00 3.34 11.18 6 6= Tutaekuri River 5.00 0.60 5.00 1.69 2.86 8 6= Porangahau River 5.14 1.03 4.00 2.73 7.48 7 8
5.3 Fish biodiversity
The NIWA administered Freshwater Fish Database (NZFFDB) has been used to compare fish communities between the 10 Hawke’s Bay rivers included in State of the Environment (SoE) monitoring. NZFFDB records pertaining to tributaries or the upper portions of these rivers has been ignored. The fifteen fish taxa recorded in the Ngaruroro is more than in any other river (Table 23; Table 24). The Tukituki, Esk, Mohaka, and Tutaekuri Rivers had records of the presence of 13 taxa. The Ngaruroro River also has the highest number of native species (13) and threatened/at risk species (8). However, due to the presence of Gambusia affinis and rainbow trout
52 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
(Oncorhynchus mykiss), it has the equal highest number of introduced and naturalised fish taxa (2). The solitary fishing record in the Clive is likely the cause of the poor ranking for number of taxa, native fish, and threatened at risk taxa, and the good ranking for introduced taxa. The dwarf galaxias (Galaxias divergens; at risk – declining) has only been observed in the Ngaruroro and the Tukituki. Furthermore, the introduced Gambusia has only been observed in the Ngaruroro and Tutaekuri River. Fish taxa observed elsewhere in the Hawke’s Bay region, yet are missing from the Ngaruroro include the native banded kokopu (Galaxias fasciatus) and the introduced brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), and goldfish (Carassius auratus).
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 53
Table 23: Fish taxa presence/absence between selected Hawkes Bay rivers. 1 = taxa present in NIWA FFDB records.
iver
Common name Scientific name Conservation status River Aropaoanui Clive River River Esk Mohaka River River Ngaruroro R Porangahau Tukituki River River Tutaekuri Waikari River Wairoa River Banded kokopu Galaxias fasciatus Not threatened 1 1 1 Bluegill bully Gobiomorphus hubbsi At risk - declining 1 1 1 1 1 1 1 Brown trout Salmo trutta Introduced and naturalised 1 1 Chinook salmon Oncorhynchus tshawytscha Introduced and naturalised 1 Common bully Gobiomorphus cotidianus Not threatened 1 1 1 1 1 1 1 1 1 Common smelt Retropinna retropinna Not threatened 1 1 1 1 1 1 1 1 Cran's bully Gobiomorphus basalis Not threatened 1 1 1 1 1 Dwarf galaxiid Galaxias divergens At risk - declining 1 1 Gambusia Gambusia affinis Introduced and naturalised 1 1 Giant bully Gobiomorphus gobioides Not threatened 1 1 1 1 1 1 1 Goldfish Carassius auratus Introduced and naturalised 1 Inanga Galaxias maculatus At risk - declining 1 1 1 1 1 1 1 1 1 Koaro Galaxias brevipinnis At risk - declining 1 1 1 1 1 Lamprey Geotria australis Threatened - nationally vulnerable 1 1 1 1 1 Longfin eel Anguilla dieffenbachii At risk - declining 1 1 1 1 1 1 1 1 1 Rainbow trout Oncorhynchus mykiss Introduced and naturalised 1 1 1 1 1 1 Redfin bully Gobiomorphus huttoni At risk - declining 1 1 1 1 1 1 1 Shortfin eel Anguilla australis Not threatened 1 1 1 1 1 1 1 1 1 Torrentfish Cheimarrichthys fosteri At risk - declining 1 1 1 1 1 1 1 1 Total native taxa richness 8 1 11 11 13 8 12 10 10 9
54 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Table 24: Fish metric summary for each Hawkes Bay selected river, including ranking each metric (grey columns). Order of rivers in table determined by the rank of taxa richness.
River (rank) count Taxa (rank) count Native Introduced count (rank) risk Threatened/at (rank) taxa Ngaruroro River 15 (1) 13 (1) 2 (7=) 8 (1) Tukituki River 13 (2=) 12 (2) 1 (3=) 7 (2) Esk River 13 (2=) 11 (3=) 2 (7=) 6 (3=) Mohaka River 13 (2=) 11 (3=) 2 (7=) 6 (3=) Tutaekuri River 12 (5) 10 (5=) 2 (7=) 6 (3=) Waikari River 10 (6=) 10 (5=) 0 (1=) 5 (6=) Wairoa River 10 (6=) 9 (7) 1 (3=) 5 (6=) Aropaoanui River 9 (8=) 8 (8=) 1 (3=) 5 (6=) Porangahau River 9 (8=) 8 (8=) 1 (3=) 3 (9) Clive River 1 (10) 1 (10) 0 (1=) 1 (10)
5.4 Regional summary
The water quality and macroinvertebrate community condition of the lower Ngaruroro River does not stand out on a regional scale (Table 25). However, the lower Ngaruroro River does have a regionally outstanding fish community in terms of taxa richness when compared to the lower sections of the main stems of nine other Hawke’s Bay rivers. Riverine avifauna were not compared on a regional scale for this report.
Table 25: Summary table of how parameters discussed above rank for the lower Ngaruroro River on a regional basis. Including whether each parameter ranks as outstanding. * denotes parameters where lowest value ranks highest. Water quality, macroinvertebrate, and fish parameters are considered outstanding if ranks in top 10% of rivers.
Regional rank
Parameter Mean Median Regionally outstanding?
Water quality
Average water quality rank 3/10 3.5/10 No
E. coli* 6/10 4/10 No
Macroinvertebrates
MCI 3/10 2/8 No
EPT 5/10 5/8 No
Regional rank
Fish
Taxa richness 1/10 Yes
Native taxa richness 1/10 Yes
Threatened/at risk taxa richness 1/10 Yes
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 55
6.0 National rivers - ecological comparison
Sixteen national rivers of comparable size have been selected to compare with Ngaruroro River. To allow for fair comparison only lowland rivers were selected where:
• There were no obvious barriers such as dams or concrete lined channels; • Surrounding land has been modified to a similar degree as the Heretaunga Plains; • Monitoring locations were upstream of the salt wedge.
Nine South Island rivers and eight North Island rivers (including Ngaruroro River) were selected to ensure different geographical regions were represented.
For consistency, data were collected as per the methodologies detailed in Sections 4.1, 4.2, and 4.3.
Refer to Section 5.0 for justification of which monitoring locations to include in the below analyses.
6.1 Water quality
Refer to Section 4.1 for descriptions of the below water quality parameters. Total nitrogen (TN), total phosphorus (TP), and dissolved inorganic nitrogen (DIN) have not been included in the below analyses due to the absence of data for rivers outside of the Hawke’s Bay region.
Furthermore, nitrite (NO2) data were only available for Ngaruroro, Rangitikei, and Manawatu River so has been excluded from the below analyses due to inability to confidently draw conclusions.
6.1.1 Dissolved oxygen
The Rakaia and Waiau Rivers had the highest mean and median dissolved oxygen concentrations of the 17 rivers included in this analysis (Figure 30; Table 26). The Ngaruroro had the second lowest median dissolved oxygen concentrations, whilst the Kaituna River was the only river below 10 mg/L dissolved oxygen.
56 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Figure 30: Dissolved oxygen (mg/L) concentrations in 17 national lowland rivers.
Table 26: Descriptive statistics for dissolved oxygen (mg/L) in 17 national lowland rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Rank Standard Standard Sample by by Mean Error Median Deviation Variance mean median Rakaia R 11.54 0.18 11.41 1.54 2.36 1 1 Waiau R 11.23 0.05 11.16 1.32 1.75 2 2 Clutha R 10.94 0.04 10.90 0.92 0.84 4 3 Ashley R 11.02 0.17 10.80 1.35 1.81 3 4 Waitaki R 10.88 0.05 10.78 1.14 1.31 5 5 Waimakariri R 10.78 0.04 10.75 1.15 1.31 6 6 Ruamahanga R 10.73 0.08 10.68 2.84 8.07 7 7= Grey R 10.65 0.05 10.68 0.88 0.77 10= 7= Wairau R 10.72 0.06 10.67 1.03 1.07 8 9 Rangitaiki R 10.65 0.04 10.66 0.73 0.54 10= 10= Rangitikei R 10.67 0.06 10.66 1.33 1.76 9 10= Mataura R 10.63 0.04 10.50 1.54 2.37 12 12 Manawatu R 10.49 0.06 10.47 1.65 2.71 13 13 Whakatane R 10.41 0.06 10.31 1.08 1.16 14 14 Mokau R 10.25 0.04 10.30 1.08 1.17 16 15 Ngaruroro R 10.27 0.06 10.21 1.27 1.61 15 16 Kaituna R 9.83 0.05 9.80 0.74 0.55 17 17
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 57
6.1.2 Water clarity
Black disk The Wairau had a median black disk measurement nearly twice that of the Ngaruroro (Figure 31; Table 27). The Ngaruroro had the seventh highest mean and eighth highest black disk measurement of the 17 national rivers.
Figure 31: Black disk measures (m) for water clarity in 17 national lowland rivers.
Table 27: Descriptive statistics for black disk measurements (m) in 17 national lowland rivers Including ranking the rivers according to mean and median measurements. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Wairau R 2.95 0.14 2.54 2.33 5.43 1 1 Waiau R 2.22 0.07 2.05 1.57 2.47 3 2 Whakatane R 2.09 0.10 1.91 1.37 1.88 4 3 Grey R 2.06 0.09 1.80 1.52 2.32 5 4 Kaituna R 1.84 0.11 1.75 0.66 0.44 6 5 Ruamahanga R 2.31 0.07 1.59 2.38 5.67 2 6 Clutha R 1.62 0.05 1.40 1.09 1.19 9 7 Ngaruroro R 1.81 0.08 1.31 1.69 2.86 7 8 Rangitaiki R 1.40 0.04 1.24 0.76 0.57 10 9 Waitaki R 1.64 0.06 1.21 1.35 1.84 8 10 Mataura R 1.04 0.02 0.89 0.85 0.72 12 11 Rangitikei R 1.17 0.06 0.70 1.22 1.50 11 12 Mokau R 0.84 0.03 0.67 0.64 0.41 14 13 Manawatu R 0.78 0.03 0.52 0.74 0.55 15 14 Waimakariri R 0.89 0.05 0.40 1.18 1.39 13 15
58 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Turbidity
The top three rivers (Ashley, Wairau, and Waiau) had median NTU levels at least 1 unit lower than the Ngaruroro (Figure 32; Table 28). Ngaruroro River ranked 11th and 10th for mean and median NTU, respectively.
Figure 32: Turbidity (NTU) for water clarity in 17 national lowland rivers.
Table 28: Descriptive statistics for turbidity (NTU) in 17 national lowland rivers Including ranking the rivers according to mean and median turbidity. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Ashley R 24.08 10.15 0.50 82.45 6.798.78 13 1 Wairau R 18.19 4.59 1.50 78.55 6.170.02 10 2 Waiau R 5.92 0.58 1.80 13.47 181.31 4 3 Rangitaiki R 3.88 0.36 2.00 6.24 38.95 2 4 Grey R 7.68 1.58 2.10 27.45 753.32 6 5 Kaituna R 2.93 0.15 2.29 2.24 5.00 1 6 Ruamahanga R 15.31 1.24 2.30 44.93 2.018.86 9 7 Clutha R 4.69 0.42 2.40 10.15 103.12 3 8 Whakatane R 8.57 1.10 2.79 18.06 326.19 7 9 Ngaruroro R 18.58 2.70 2.80 63.51 4.033.34 11 10 Rakaia R 19.69 6.64 3.20 56.37 3.177.49 12 11 Waitaki R 6.96 1.06 3.50 25.48 649.21 5 12 Mataura R 13.01 0.75 4.60 28.06 787.18 8 13 Rangitikei R 66.73 12.33 5.99 272.83 74.436.50 17 14 Mokau R 31.30 6.88 6.90 178.06 31.705.67 14 15 Waimakariri R 41.10 3.95 9.30 112.09 12.564.70 15 16 Manawatu R 61.69 7.08 11.00 206.06 42.459.37 16 17
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 59
6.1.3 Nutrients
Dissolved Reactive Phosphorus (DRP) The Waitaki and Clutha rivers had the lowest mean DRP, at < 2 μg/L (Figure 33 and Table 29). Seven rivers (the Kaituna, Whakatane, Rangitaiki, Manawatu, Mataura, Mokau, and Raumahanga) had high mean levels of DRP (>10 μg/L), and appear to fluctuate considerably. The Ngaruroro river had the 9th lowest mean and median concentrations of DRP.
Figure 33: Dissolved reactive phosphorus (DRP) concentrations in 17 national lowland rivers.
Table 29: Descriptive statistics for dissolved reactive phosphorus (DRP) concentrations in 17 national lowland rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Waitaki R 1.91 0.19 0.98 4.58 20.99 2 1 Clutha R 1.64 0.09 1.00 2.12 4.49 1 2 Rakaia R 2.18 0.20 2.00 1.74 3.03 3 3 Waiau R 2.86 0.10 2.04 2.24 5.02 5 4 Grey R 2.73 0.11 2.29 1.89 3.59 4 5 Waimakariri R 4.68 0.23 2.61 6.55 42.87 8 6 Ashley R 3.98 0.38 3.00 3.05 9.27 7 7 Wairau R 3.96 0.15 3.11 2.51 6.31 6 8 Ngaruroro R 5.75 0.22 5.00 5.23 27.36 9 9 Rangitikei R 8.22 0.35 6.28 7.80 60.92 10 10 Ruamahanga R 11.02 0.34 8.00 12.33 151.96 11 11 Mokau R 11.61 0.27 10.00 6.83 46.66 12 12 Mataura R 18.64 0.49 14.00 18.76 351.82 13 13 Manawatu R 22.92 0.62 19.00 18.29 334.61 15 14 Rangitaiki R 18.85 0.62 20.86 10.80 116.72 14 15 Whakatane R 23.21 0.45 23.00 7.49 56.14 16 16 Kaituna R 25.77 0.82 24.00 12.32 151.76 17 17
60 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Nitrate (NO3) The Waitaki, Clutha and Rakaia rivers had the lowest mean and median concentrations of nitrate (Figure 34 and Table 30). The Mokau, Manawatu and Mataura rivers had the highest levels, and (along with the Raumahanga) fluctuate substantially. The Ngaruroro river had the fourth lowest mean and the fifth lowest median nitrate concentration.
Figure 34: Nitrate (NO3) concentrations in 17 national lowland rivers.
Table 30: Descriptive statistics for nitrate (NO3) concentrations in 17 national lowland rivers including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Waitaki R 48.22 3.19 27.00 76.48 5,848.54 1 1 Clutha R 65.98 3.19 41.11 76.44 5,842.63 3 2 Rakaia R 51.49 2.97 55.00 25.40 644.99 2 3 Wairau R 98.35 5.39 67.40 92.07 8,477.35 6 4 Ngaruroro R 95.75 3.51 69.22 98.51 9,705.11 4 5 Whakatane R 97.12 4.69 79.99 77.77 6,048.40 5 6 Waimakariri R 150.28 8.89 83.69 252.79 63,903.98 9 7 Grey R 99.39 3.54 85.00 59.93 3,592.01 7 8 Rangitikei R 127.08 9.68 88.00 203.47 41,401.39 8 9 Ashley R 167.95 14.98 150.00 120.78 14,588.33 10 10 Waiau R 195.10 6.17 164.00 139.67 19,508.31 11 11 Ruamahanga R 361.38 9.36 301.56 338.24 114,406.60 14 12 Kaituna R 348.32 10.68 326.00 158.06 24,982.53 13 13 Rangitaiki R 344.60 7.72 346.64 134.96 18,215.31 12 14 Mokau R 430.00 9.39 370.00 239.53 57,373.21 15 15 Manawatu R 571.61 11.84 520.00 335.10 112,293.11 16 16 Mataura R 854.92 10.11 820.00 363.28 131,972.97 17 17
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 61
Ammoniacal nitrogen - ammonium (NH4) The Waimakariki and Wairau rivers had the lowest mean and median concentrations of ammonium (Figure 35 and Table 31). The Mataura, Kaituna and Manawatu rivers had concentrations substantially higher than any of the other streams, with much wider fluctuations. The Ngaruroro river had the fifth lowest mean and median ammonium concentrations.
Figure 35: Ammonium (NH4) concentrations in 17 national lowland rivers.
Table 31: Descriptive statistics for Ammonium (NH4) concentrations in 17 national lowland rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Waimakariri R 3.30 0.13 2.39 3.04 9.26 1 1 Wairau R 4.10 0.19 3.01 3.13 9.80 2 2 Clutha R 4.78 0.18 3.60 4.18 17.51 4 3 Waitaki R 4.27 0.14 3.65 3.26 10.60 3 4 Ngaruroro R 5.04 0.25 4.00 4.05 16.44 5 5 Waiau R 6.53 0.26 5.00 5.73 32.78 6 6= Rangitikei R 8.52 0.52 5.00 11.40 129.90 8 6= Grey R 7.08 0.33 5.97 5.47 29.96 7 8 Ruamahanga R 12.23 0.38 7.00 13.51 182.48 11 9 Whakatane R 11.00 1.16 8.00 19.43 377.50 9 10 Mokau R 14.18 0.49 10.00 12.42 154.27 12 11 Rangitaiki R 12.04 0.48 11.00 8.16 66.59 10 12 Mataura R 42.22 1.68 26.00 62.26 3,876.10 13 13 Kaituna R 46.08 2.92 29.99 43.38 1,882.22 14 14 Manawatu R 52.60 1.89 40.51 54.52 2,972.36 15 15
62 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
6.1.4 pH
The pH levels at all sites fall within a range (refer Section 4.1) that is unlikely to harm aquatic biota (Figure 36; Table 32).
Figure 36: pH levels in 17 national lowland rivers.
Table 32: Descriptive statistics for pH levels in 17 national lowland rivers Including ranking the rivers according to mean and median levels. Ngaruroro River has been highlighted in red to allow for easy identification.
Mean Standard Error Median Standard Deviation Sample Variance Range Minimum Maximum Ashley R 7.67 0.03 7.60 0.21 0.04 1.10 7.00 8.10 Clutha R 7.77 0.01 7.76 0.14 0.02 1.14 7.27 8.41 Grey R 7.31 0.02 7.33 0.33 0.11 2.42 6.02 8.44 Kaituna R 6.90 0.01 6.90 0.21 0.04 1.80 6.00 7.80 Manawatu R 7.71 0.01 7.62 0.42 0.17 2.87 6.44 9.31 Mataura R 7.24 0.00 7.20 0.17 0.03 1.80 6.20 8.00 Mokau R 7.41 0.01 7.40 0.28 0.08 1.90 6.40 8.30 Ngaruroro R 8.00 0.02 7.93 0.37 0.13 2.55 6.87 9.42 Rakaia R 7.69 0.03 7.70 0.23 0.05 1.10 6.90 8.00 Rangitaiki R 7.09 0.01 7.07 0.15 0.02 0.98 6.71 7.69 Rangitikei R 7.90 0.02 7.92 0.33 0.11 3.68 5.42 9.10 Ruamahanga R 7.59 0.01 7.56 0.35 0.12 3.86 5.78 9.64 Waiau R 7.66 0.01 7.60 0.34 0.12 2.14 6.90 9.04 Waimakariri R 7.71 0.01 7.70 0.21 0.04 2.27 6.60 8.87 Wairau R 7.76 0.02 7.70 0.35 0.12 2.12 6.94 9.06 Waitaki R 7.73 0.01 7.72 0.19 0.04 1.64 6.96 8.60 Whakatane R 7.40 0.01 7.40 0.25 0.06 1.91 6.19 8.10
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 63
6.1.5 Bacteriological water quality
E. coli Only the Wairau, Waitaki and Rakaia rivers had median E. coli concentrations lower than (or equal to) the Ngaruroro, though for mean concentrations the Ngaruroro ranked eighth (Figure 37, Table 33). The Rangitikei, Manawatu, Mokau and Mataura rivers had the highest mean and median E. coli concentrations.
Figure 37: E. coli concentrations in 17 national lowland rivers.
Table 33: Descriptive statistics for E. coli concentrations in 17 national lowland rivers Including ranking the rivers according to mean and median concentrations. Ngaruroro River has been highlighted in red to allow for easy identification. Rank Standard Standard Sample by Rank by Mean Error Median Deviation Variance mean median Wairau R 41.51 15.35 6.80 148.82 22148.31 2 1 Waitaki R 36.71 5.25 9.80 71.76 5148.94 1 2 Rakaia R 98.97 28.00 17.00 237.61 56456.92 5 3= Ngaruroro R 163.38 69.96 17.00 986.97 974109.10 8 3= Ashley R 88.66 22.08 22.00 248.87 61935.08 4 5 Clutha R 120.54 24.73 22.05 339.14 115015.66 6 6 Grey R 200.64 41.55 30.00 460.79 212323.39 10 7 Rangitaiki R 79.00 12.89 32.70 136.39 18601.00 3 8 Waiau R 187.74 26.54 36.00 522.04 272524.65 9 9 Ruamahanga R 284.98 31.62 47.00 851.38 724842.03 13 10 Kaituna R 259.11 51.28 57.00 750.18 562770.80 12 11 Whakatane R 160.28 20.97 60.00 341.35 116516.47 7 12 Waimakariri R 255.69 22.40 100.70 459.05 210730.70 11 13
64 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Rangitikei R 1868.76 523.12 163.30 8908.44 79360242.41 17 14 Manawatu R 1113.13 132.12 210.00 2784.01 7750727.08 14 15 Mokau R 1192.88 391.72 240.00 4861.16 23630837.12 15 16 Mataura R 1232.88 92.24 380.00 2875.68 8269547.80 16 17
6.2 Macroinvertebrates
6.2.1 MCI scores
The Rangitaiki had the highest mean and median MCI scores, while the Kaituna and Clutha rivers had the lowest (Figure 38 and Table 34). Ngaruroro had the eighth highest mean and median score.
Figure 38: MCI values for 17 national lowland rivers.
Table 34: Descriptive statistics for MCI values for 17 national lowland rivers Including ranking the rivers according to mean and median scores. Ngaruroro River has been highlighted in red to allow for easy identification. Standard Standard Sample Rank of Rank of River Mean Error Median Deviation Variance mean median Rangitaiki 118.65 7.65 118.65 10.82 117.05 1 1 Whakatane 116.50 6.50 116.50 9.19 84.50 2 2 Rangitikei 115.90 1.24 115.90 1.75 3.07 3= 3 Ashley 113.76 2.56 112.50 14.73 217.05 5 4 Waimakiriri 111.03 0.00 111.03 - - 6 5 Ruamahanga 115.90 4.04 110.00 21.40 457.93 3= 6 Mataura 107.86 2.26 107.53 16.30 265.83 7 7 Ngaruroro 106.71 1.28 106.67 8.80 77.48 8 8 Waiau 96.36 5.99 101.67 14.67 215.34 14 9 Wairau 102.32 4.79 100.00 9.58 91.87 9 10 Mokau 96.82 1.70 97.50 5.65 31.91 12 11 Grey 96.67 0.00 96.67 - - 13 12=
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 65
Standard Standard Sample Rank of Rank of River Mean Error Median Deviation Variance mean median Waitaki 100.09 3.41 96.67 12.74 162.35 10 12= Rakaia 99.42 4.28 93.85 9.57 91.64 11 14 Manawatu 85.75 3.86 84.00 20.06 402.49 15 15 Kaituna 77.83 6.24 75.00 15.28 233.37 17 16 Clutha 81.13 10.71 71.67 18.54 343.91 16 17
6.2.2 EPT taxa richness
The lower Ngaruroro River has the eight equal highest mean and median EPT taxa richness of the 14 national rivers were detailed data were available (Figure 39; Table 35). The lower Ngaruroro also had one of the larger ranges of EPT taxa richness, suggesting the EPT richness fluctuates relatively more than in many of the other rivers.
Figure 39: EPT taxa richness for 14 of the 17 national lowland rivers.
Table 35: Descriptive statistics for EPT richness for 14 of the 17 national lowland rivers Including ranking the rivers according to mean and median richness. Ngaruroro River has been highlighted in red to allow for easy identification. Standard Standard Sample Rank of Rank of River Mean Error Median Deviation Variance mean median
Waimakiriri 24.00 0.00 24.00 N/A N/A 1 1 Rakaia 15.00 2.00 15.00 2.83 8.00 3 2 Ruamahanga 15.10 1.73 14.00 7.91 62.59 2 3 Mataura 8.26 0.32 8.00 2.01 4.04 4 4 Wairau 6.50 1.26 7.00 2.52 6.33 6= 5 Rangitikei 6.50 1.50 6.50 2.12 4.50 6= 6= Waitaki 6.93 0.46 6.50 1.73 2.99 5 6= Ashley 5.85 0.27 6.00 1.54 2.38 10 8= Ngaruroro 6.17 0.34 6.00 2.17 4.70 8= 8= Clutha 4.00 1.00 5.00 1.73 3.00 12 10= Mokau 5.45 0.39 5.00 1.29 1.67 11 10=
66 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Standard Standard Sample Rank of Rank of River Mean Error Median Deviation Variance mean median
Waiau 6.17 1.92 5.00 4.71 22.17 8= 10= Grey 3.00 0.00 3.00 N/A N/A 13 13 Manawatu 1.70 0.31 1.00 1.61 2.60 14 14
6.3 Fish biodiversity
For the lowland river national comparison (17 rivers analysed), 28 species of fish have been observed in total (Table 36). However, the shortjaw kokopu (Galaxias postvectis) and upland longjaw galaxiid (G. prognathous) were only observed in a single river each (Grey River and Rakaia River, respectively). Alternatively, longfin eel (Anguilla dieffenbachii) and common bully (Gobiomorphus cotidianus) were present in all 17 rivers. Torrentfish (Cheimarrichthys fosteri) and brown trout (Salmo trutta), and shortfin eel (A. australis) were also common (present in 16 and 15 rivers, respectively). In the lowland river sections, the Waitaki River has the highest species richness, as well as the highest number of natives and threatened/at risk species (Table 37). The Whakatane river contains the lowest overall and native species richness, while the Rangitikei has the lowest number of threatened/at risk species. The Ngaruroro river ranks fifth best for both total richness and threatened/at risk species richness, however it ranks second best for native taxa richness.
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018 67
Table 36: Species observed in 17 national lowland rivers. Ngaruroro River has been highlighted in red to allow for easy identification.
River
Scientific name Common name Conservation status River Ashley Clutha River River Grey Kaituna River River Manawatu Mataura River River Mokau River Ngaruroro Rakaia Rangitaiki River Rangitikei River River Ruamahanga River Waiau Waimakariri River River Wairau Waitaki River River Whakatane Anguilla australis Shortfin eel Not threatened 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Anguilla dieffenbachii Longfin eel At risk - declining 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Carassius auratus Goldfish Introduced and naturalised 1 1 1 Cheimarrichthys fosteri Torrentfish At risk - declining 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Galaxias argenteus Giant kokopu At risk - declining 1 1 1 Galaxias brevipinnis Koaro At risk - declining 1 1 1 1 1 1 1 1 1 1 Galaxias divergens Dwarf galaxiid At risk - declining 1 1 1 1 Galaxias fasciatus Banded kokopu Not threatened 1 1 1 1 Galaxias gollumoides Gollum galaxiid Threatened - naturally vulnerable 1 Galaxias maculatus Inanga At risk - declining 1 1 1 1 1 1 1 1 1 1 1 1 Galaxias paucispondylus Alpine galaxiid At risk - naturally uncommon 1 1 1 1 Galaxias postvectis Shortjaw kokopu Threatened - naturally vulnerable 1 Galaxias prognathus Upland longjaw galaxiid Threatened - naturally vulnerable 1 Galaxias vulgaris Canterbury galaxiid At risk - declining 1 1 1 1 Gambusia affinis Gambusia Introduced and naturalised 1 1 1 1 Geotria australis Lamprey Threatened - naturally vulnerable 1 1 1 1 1 1 1 1 1 1 1 Gobiomorphus basalis Crans bully Not threatened 1 1 1 1 1 1 Gobiomorphus breviceps Upland bully Not threatened 1 1 1 1 1 1 1 1 1 1 1 1 Gobiomorphus cotidianus Common bully Not threatened 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Gobiomorphus gobioides Giant bully Not threatened 1 1 1 1 1 Gobiomorphus hubbsi Bluegill bully At risk - declining 1 1 1 1 1 1 1 1 1 1 Gobiomorphus huttoni Redfin bully At risk - declining 1 1 1 1 1 1 1 1 1 Oncorhynchus mykiss Rainbow trout Introduced and naturalised 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Oncorhynchus tshawytscha Chinook salmon Introduced and naturalised 1 1 1 1 1 1 Perca fluviatilis Perch Introduced and naturalised 1 1 1 1 Retropinna retropinna Common smelt Not threatened 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Salmo trutta Brown trout Introduced and naturalised 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Stokellia anisodon Stokells smelt At risk – naturally uncommon 1 1 1 Total native taxa richness 10 10 13 12 9 10 9 13 12 9 8 11 11 12 8 14 7
68 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Table 37: Number of species found in 17 national lowland rivers. Rivers have been ranked based on total count, native species, introduced species and threatened/at risk species. Ngaruroro River has been highlighted in red to allow for easy identification.
River Taxa count Native count Introduced count Threatened/at risk taxa Waitaki River 18 (1) 15 (1) 3 (7=) 10 (1=) Kaituna River 16 (2=) 12 (6) 4 (14=) 6 (7=) Rakaia River 16 (2=) 13 (2=) 3 (7=) 10 (1=) Waimakariri River 16 (2=) 13 (2=) 3 (7=) 9 (3=) Ngaruroro River 15 (5) 13 (2=) 2 (3=) 8 (5) Clutha River 14 (6=) 10 (9=) 4 (14=) 5 (12) Grey River 14 (6=) 13 (2=) 1 (1=) 9 (3=) Ruamahanga River 14 (6=) 11 (7=) 3 (7=) 6 (7=) Waiau River 14 (6=) 11 (7=) 3 (7=) 7 (6) Mokau River 13 (10=) 9 (12=) 4 (14=) 4 (13=) Rangitaiki River 13 (10=) 9 (12=) 4 (14=) 4 (13=) Ashley River 12 (12) 10 (9=) 2 (3=) 6 (7=) Manawatu River 12 (12) 9 (12=) 3 (7=) 4 (13=) Mataura River 11 (14) 10 (9=) 1 (1=) 6 (7=) Rangitikei River 11 (14) 8 (15=) 3 (7=) 3 (17) Wairau River 10 (16) 8 (15=) 2 (3=) 6 (7=) Whakatane River 9 (17) 7 (17) 2 (3=) 4 (13=)
We expanded the comparative data set to all rivers in NZ were there was adequate data. That analysis shows that the Buller River has 20 native fish taxa recorded in the NZFFD which is the highest richness. Four rivers have records of 19 native fish taxa within their catchments, compared to the Ngaruroro which has 14 native fish taxa present in the catchment. In total, 30 rivers have more than 14 native fish taxa recorded in their catchments; therefore, the Ngaruroro ranks 31st= in native fish taxa diversity on a national scale (10.2nd percentile). We however, considered that the common and ubiquitous fish were overly weighted in this comparison, and threatened fish under weighted; and determined to formed a threatened-at risk taxa indices (see below) to remove the effect of the common ubiquitous taxa. For this to occur, each fish taxa were assigned a ‘value’ as determined by the threat classification of that species (Table 38). The sum of the taxa values was totalled to give each river a value based on the relative importance of the native fish diversity. For the purpose of this report we have termed this the ‘threat classification indices (TCI)’.
69 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Table 38: Threat classifications and the assigned threat classification indices (TCI) values for the purpose of comparing the 'importance' of the native fish diversity between national rivers. Assigned Threat classification TCI value Threatened
Nationally critical 8
Nationally endangered 7
Nationally vulnerable 6
At risk
Declining 5
Recovering 4
Relict 3
Naturally uncommon 2
Not threatened
Not threatened 1
The TCI of the Ngaruroro is 47, which is 37 TCI points below the Clutha River (84) which ranked highest using this method. The Buller River, which had the greatest number of native fish taxa, ranked 3rd according to the TCI method (TCI = 76). Against the 303 rivers included in this analysis, the Ngaruroro catchment ranks 54th= which puts it in the 17.8th percentile. In summary, when acknowledging the number of native fish taxa within river catchments (excluding lakes and wetlands) the Ngaruroro River currently lies 0.2 of a percentage point outside of the top 10% of national rivers in terms of total native taxa. However, the Ngaruroro only ranks in the top 17.8% of national rivers according to the TCI. That is the Ngaruroro is not “outstanding” in terms of native fish value.
6.4 Avian population estimates and national proportions
Table 39. Summary of the avifauna species that utilise the Lower Ngaruroro River and whether the reach is nationally outstanding for each species.
Species Ngaruroro River National National Nationally Population Population Population Outstanding Proportion (%) habitat Australasian bittern 13 500-7504 0.1-0.25 No Black-billed gull 400-600 15000 2.7-4 No Grey duck 30 -1 -1 Unknown White heron At least 1 150-200 - 2 No Black-fronted tern 30-75 5000 0.01 No Banded dotterel 500 25000-50000 1-2 No Caspian tern Rarely sighted6 3000 -2 No Wrybill 1 4500-5500 0.02 No Marsh crake Unspecified number 5000-20000 -2 No New Zealand pipit 247 >100000 -2 No Red-billed gull A few birds8 >100000 -2 No
Appendix 1: Macroinvertebrate monitoring locations – all rivers Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | [Subject]
South Island pied 10 90000-130000 0.008-0.01 No oystercatcher Spotless crake Unspecified number 5000-20000 -2 No Australasian pied stilt 173-461 30000 0.6-1.5 No New Zealand dabchick Unspecified number 1700 -2 No Black-fronted dotterel 39-145 2000 1.95-7.25 Yes Black shag 3-18 10000-20000 <0.2 No Little black shag 0-16 2000-10000 0.2-0.8 No
1 Due to hybridisation with mallard ducks, there is uncertainty about the national population of grey; consequently, the Ngaruroro River population as a proportion of the national population cannot be calculated.
2 There is uncertainty about the size of the Ngaruroro River population therefore the proportion of the national population cannot be calculated.
3 Likely sighting but unconfirmed.
5 Conservative estimate using the unconfirmed bittern sighting and the likely underestimated national population size.
4 Most likely an underestimate of the national population due to the cryptic nature of the species and difficultly detecting them during surveys.
6 Unspecified number of birds observed.
7 Underestimate of Lower Ngaruroro River population as only the Otamauri Stream to Mangatahi section was surveyed.
8 Unspecified number of birds observed.
Summary
The Lower Ngaruroro River has a diversity of avifauna habitats, however in general, habitat quality is not high due to the dominance of exotic vegetation, weeds and channelization. 17 Threatened and At Risk avifauna species utilise the Lower Ngaruroro River, one of which (black-fronted dotterel) has a potential Ngaruroro population that is considered to be outstanding on a national scale (i.e. at any one time, the reach supports 5 % or more of the national population of this species); this is based on Lower Ngaruroro River black-fronted dotterel population estimates towards the higher end of various survey data as their numbers appear to have stabilised towards the higher end of the survey range reported. The other 16 Threatened and At Risk species considered did not reach the 5 % threshold, therefore the Lower Ngaruroro River is not considered to be outstanding habitat for these avifauna species
71 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
7.0 Assessment of outstanding
The lower Ngaruroro River has been highly modified for a range of purposes (e.g. water abstraction for irrigation, flood protection, gravel extraction). The riparian margin is dominated by exotic vegetation, artificial stop-banks have been created, the river flows through an artificial diversion below Chesterhope, numerous permitted water extractions have resulted in the river flowing below its natural rate, the gravel bed is frequently manipulated to increase flood capacity and control nuisance weed growth, and frequent gravel extraction operations result in decreased gravel loads and modified flow. Also, through a combination of the above, the braided pattern of the lower Ngaruroro is sufficiently impacted to cause the river to flow in a single channel for sections. Irrespective of the modified state, the lower river has regionally low levels of nutrients as compared with the lowland portions of nine other large Hawke’s Bay rivers. However, dissolved oxygen, water clarity, and E. coli levels do not rank highly amongst the region’s rivers. Furthermore, the water quality in the lower Ngaruroro River did not appear to rank highly (within the top 10% of rivers) when compared against the lowland sections of 16 national rivers. Macroinvertebrate community health appears to decline along a downstream gradient in the lower Ngaruroro River; however, the overall mean and median MCI scores are suggestive of good water quality. The MCI score and EPT taxa richness of the lower Ngaruroro River, when compared against the 16 national lowland rivers, ranked eighth equal for mean and median values. This suggests, whilst the MCI score is suggestive of good water quality, it is well outside of the top 10% of national lowland rivers, and, therefore, also all national large rivers. The fish community of the lower Ngaruroro River is regionally important as it has the highest taxa richness, including highest number of native taxa, and it has the highest number of threatened or at risk taxa of the nine other major Hawke’s Bay rivers assessed in this report. However, on a national scale, native taxa richness could be included in the top 10% of national lowland rivers. Acknowledging that there are other rivers such as the Rangitata (Bonnett, 1986), which have higher native species richness not used in this comparative assessment. However, when a wider set of rivers nationally are compared (as we believe the “outstanding” test requires) the Ngaruroro is not “outstanding”, especially where the comparison is weighted for at risk and threatened taxa. The Lower Ngaruroro River has a diversity of avifauna habitats, however in general, habitat quality is not high. One of the avian taxa present (black-fronted dotterel) does have a potential population that under the threshold adopted is considered to be “outstanding” on a national scale (i.e. at any one time, the reach supports 5 % or more of the national population of this species); but this is based on estimates towards at the higher end of various survey data and their numbers appear to have stabilised towards the higher end of the survey range reported. The other 16 Threatened and At Risk species considered did not reach the 5 % threshold, therefore the Lower Ngaruroro River is not considered to be outstanding habitat for these avifauna species.
There is one “outstanding” characteristics as defined in this report, it is not a unique characteristics and taken in consideration of the lower river and its condition as a whole
72 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
provides only a minor weighting towards the overall ecological condition of the habitat. It is clear that the lower Ngaruroro River is “outstanding” at a regional scale, but not so at a national scale.
Table 40: Summary table of how parameters discussed above rank for the lower Ngaruroro River on a regional and national scale. Including whether each parameter ranks as outstanding. * denotes parameters where lowest value ranks highest. Water quality, macroinvertebrate, and fish parameters are considered outstanding if ranks in top 10% of nations rivers. Avifauna are considered outstanding if Ngaruroro populations accounts for >5% of national population. Regional rank National rank
Parameter Mean Median Mean Median Nationally outstanding?
Water quality
Dissolved oxygen 5/10 5/10 15/17 16/17 No
Black disk 5/10 7/10 7/15 8/15 No
Turbidity* 6/10 8/10 11/17 10/17 No
Total nitrogen* 2/10 1/10 - - No (yes – on regional scale)
Total phosphorus* 1/10 1=/10 - - No (yes – on regional scale)
Dissolved inorganic nitrogen* 1/10 3/10 - - No (yes – on regional scale)
Dissolved reactive phosphorus* 1/10 2/10 9/17 9/17 No
Nitrate* 1/10 3/10 4/17 5/17 No
Nitrite* 2/10 1/10 No (yes – on regional scale)
Ammonium* - - 5/15 5/15 No
E. coli* 6/10 4/10 8/17 3=/17 No
Macroinvertebrates
MCI 3/10 2/8 8/17 8/17 No
EPT 5/10 5/8 8=/14 8=/14 No
Regional rank National rank
Fish
Taxa richness 1/10 5/17 No
Native taxa richness 1/10 2=/17 No
Threatened/at risk taxa richness 1/10 5/17 No
1 of 17 species potentially representing > 5% of Riverine Avian national population Yes - for black fronted dotterel
73 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
8.0 References
Asset Management Group. (2003). Revised environmental code of practice for river control and
drainage works (No. AM 03/12). Napier: Asset Management Group prepared for
Hawke’s Bay Regional Council.
Bonnett, M. L. (1986). Fish and benthic invertebrate populations of the Rangitata River
(Fisheries Environmental Report No. 62). Christchurch: Ministry of Agriculture and
Fisheries, Fisheries Research Division.
Dowding, J. E., & Moore, S. J. (2006). Habitat networks of indigenous shorebirds in New
Zealand (Science for Conservation No. 261). Wellington: Department of Conservation.
Environmental Management Services Limited. (2016). Hawkes Bay gravel management study:
RMA issues and gravel demand drivers (No. HBRC Report No. AM 17-02). Napier:
Environmental Management Services Limited prepared for Hawke’s Bay Regional
Council.
Goodman, J. M., Dunn, N. R., Ravenscroft, P. J., Allibone, R. M., Boubee, J. A. T., David, B. O.,
… Rolfe, J. R. (2014). Conservation status of New Zealand freshwater fish, 2013 (New
Zealand Threat Classification Series No. 7). Wellington: Department of Conservation.
Hawke’s Bay Catchment Board. (1954). Drainage & flood control - Heretaunga Plains: report on
Ngaruroro River. Hawke’s Bay Catchment Board.
Hawke’s Bay Regional Council. (2011). Lower Ngaruroro River instream flow assessment.
Napier: Hawke’s Bay Regional Council.
Hawke’s Bay Regional Council. (2017). Hawke’s Bay Riverbed Gravel Management Plan: draft
for consultation. Hawke’s Bay.
Heather, B. D., & Robertson, H. A. (2000). The field guide to the birds of New Zealand.
Auckland: Penguin Books.
Heather, B. D., & Robertson, H. A. (2015). The field guide to the birds of New Zealand.
Auckland: Penguin Books.
74 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Heather, B., & Robertson, H. A. (2005). The field guide to the birds of New Zealand. Auckland:
Penguin Books.
Maloney, R. F., Rebergen, A. L., Nilsson, R. J., & Wells, N. J. (1997). Bird density and diversity,
in braided river beds in the Upper Waitaki Basin, South Island, New Zealand. Notornis,
44, 219–232.
Maxwell, F. A., Adams, J., & Walls, G. (1993). Eastern Hawke’s Bay Ecological District: Survey
report for the Protected Natural Areas Programme (New Zealand Protected Natural
Areas Programme No. 28). Napier: Department of Conservation.
MWH. (2010a). Ngaruroro River flow naturalisation. Wellington: MWH prepared for Hawke’s Bay
Regional Council.
MWH. (2010b). Ngaruroro River high flow allocation June to November period. Wellington:
MWH prepared for Hawke’s Bay Regional Council.
MWH. (2011). Ngaruroro River Flood Protection and Drainage Scheme: Ecological
Management and Enhancement Plan (No. HBRC report AM 11-04). MWH prepared for
Hawke’s Bay Regional Council.
O’Donnell, C. F. J., & Robertson, H. A. (2016). Changes in the status and distribution of
Australasian bittern (Botaurus poiciloptilus) in New Zealand, 1800s−2011. Notornis,
63(3–4).
Parrish, G. R. (1988). Wildlife and wildlife habitat of Hawke’s Bay rivers (No. Science &
Research Series No.2). Wellington: Department of Conservation.
Pierce, R. (1999). Regional patterns patterns of migration in the banded dotterel (Charadrius
bicinctus bicinctus). Notornis, 46, 101–122.
Robertson, C. J. R., Hyvonen, P., Fraser, M. J., & Pickard, C. J. (2007). Atlas of bird distribution
in New Zealand: 1999-2004. Wellington: Ornithological Society of New Zealand.
Robertson, H. A., Baird, K., Dowding, J. E., Elliott, G. P., Hitchmough, R. A., Miskelly, C. M., …
Taylor, G. A. (2017). Conservation status of New Zealand birds, 2016 (New Zealand
Threat Classification Series No. 19). Wellington: Department of Conservation.
Southey, I. (2009). Numbers of waders in New Zealand 1994-2003 (DOC Research &
Development Series No. 308). Wellington: Department of Conservation.
75 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Special Tribunal to Consider an Applicationfor a Water Conservation Order for the Hurunui
River. (2009). Special Tribunal Hurunui water conservation order application report.
Ministry for the Environment.
Stark, J. D. (1993). Performance of the Macroinvertebrate Community Index: Effects of
sampling method, sample replication, water depth, current velocity, and substratum on
index values. New Zealand Journal of Marine and Freshwater Research, 27(4), 463–
478.
Stark, J. D., & Maxted, J. R. (2004). Macroinvertebrate community indices for Auckland soft-
bottomed streams (Auckland Regional Council Technical Publication No. TP303).
Auckland: Cawthron Institute for Auckland Regional Council.
Stark, J. D., & Maxted, J. R. (2007). A user guide for the Macroinvertebrate Community Index
(Cawthron Report No. 1166). Cawthron Institute, prepared for the Ministry for the
Environment.
Stephenson, B. M. (2009). Baseline study and assessment of effects on braided riverbed bird
communities (Final Report). Eco-Vista Photography & Research Ltd.
Wagenhoff, A., & Young, R. (2013). Effects of willow removal on australian and new zealand
stream ecosystems — a literature review of the potential risks and benefits (No. 2315).
Nelson: Cawthron Institute for MBIE.
76 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale | 20 February 2018
Appendix 1: Macroinvertebrate monitoring locations – all rivers
River Monitoring location Easting Northing Monitoring years Regional rivers Aropaoanui River Sideless Bridge 2853243 6207289 2003 - 2010 Esk River Berry Road 2837736 6212481 2003, 2005 - 2010 Waipunga Bridge 2839017 6195088 2003 - 2009 Mohaka River Raupunga 2868145 6227701 2003 - 2010 Willowflat 2851834 6237001 2003 - 2010 Porangahau River SH52 2814330 6094858 2003, 2005 - 2010 Tukituki River Ashcott Road 2796308 6135724 2003 - 2010 Black Bridge 2847566 6170374 2003 - 2010 Red Bridge 2846674 6158087 2003 - 2010 Shag rock 2826307 6133014 2004 - 2010 Tutaekuri River Brookfields Bridge 2843370 6174562 2003 - 2010 Waikari River Glenbrook Road 2857492 6221227 2003 - 2010
National Rivers Ashley River Ashley Gorge 2447300 5775400 1999 – 2005, 2007 - 2010 SH1 2484500 5770000 1999 - 2010 Clutha River Above Balclutha 2258400 5436600 2001 Finegand 2259500 5431300 2001 Kaitangata 2266100 5429000 2001 Grey River Ngahere 2380800 5867700 1998 Kaituna River Manawatu River Opiki 2719400 6082700 1999, 2002, 2005 - 2010 Teachers College 2734252 6089019 1999 - 2010 Whirokino 2702200 6074700 1999 – 2003, 2009 - 2010 Mataura River Mataura Bridge 2190639 5437453 1997 – 2001, 2003 - 2010 Gore 2196731 5448625 2009 - 2010 Keowns Road Bridge 2172046 5480614 1997 - 2010 Mataura Island Bridge 2185132 5416055 1997 – 2004, 2006 - 2010 Otamita Bridge 2188771 5458506 1997 – 2001, 2003 - 2007 Mokau River Off Paekaka Road 1 2681424 6293684 2007 Off Paekaka Road 2 2682699 6294584 2007 Off Paekaka Road 3 2683749 6295004 2007 Totoro Road 2675900 6290700 2002 - 2009 Rakaia River Rangitaiki River Rangitikei River Onepuhi 2721443 6122634 2009 - 2010 Ruamahanga River Gladstone Bridge 2731225 6012049 2004 - 2010 McLays 2728161 6047524 2004 - 2010 Pukio 2707855 5992730 2004 - 2010 Te Ore Ore 2735588 6024740 2004 - 2010 Waiau River Duncraigen Road 2096068 5496558 2008 - 2009 Tuatapere 2099400 5439700 1997, 1999 - 2001 Waimakariri River Wairau River SH1 Tuamarina 2590635 5973743 2007 – 2008, 2010 - 2011 Waitaki River Waitaki 2319800 5613600 1999 – 2005, 2007, 2009 - 2010 Whakatane River
Appendix 1: Macroinvertebrate monitoring locations – all rivers Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River
Appendix 2: NIWA assigned catchment numbers for each river as used for fish analyses
Catchment Catchment River River number number Regional rivers National rivers Ngaruroro River 231.000 Ashley River 662.000 Aropaoanui River 225.000 Clutha River 752.000 Clive River 231.500 Grey River 914.000 Esk River 228.000 Kaituna River 146.000 Mohaka River 218.000 Manawatu River 325.000 Porangahau River 243.000 Mataura River 775.000 Tukituki River 232.000 Mokau River 407.000 Tutaekuri River 230.000 Rakaia River 685.000 Waikari River 222.000 Rangitaiki River 154.000 Wairoa River 214.000 Rangitikei River 327.000 Ruamahanga River 292.000 Waiau River 797.000 Waimakariri River 664.000 Wairau River 601.000 Waitaki River 711.000 Whakatane River 155.000
Appendix 2: NIWA assigned catchment numbers for each river as used for fish analyses Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Appendix 3: OSNZ Squares Full Avifauna Species List
SPECIES - Robertson et al. 2017 CONSERVATION STATUS - Robertson et al. 2017
DP Sp TO Australasian Bittern Botaurus poiciloptilus Nativ e Threatened Nationally Critical RF Black-billed Gull Larus bulleri Endemic Threatened Nationally Critical SO Grey Duck Anas s. superciliosa Nativ e Threatened Nationally Critical OL SO St White Heron Ardea modesta Nativ e Threatened Nationally Critical RF SP Black-fronted Tern Chlidonias albostriatus Endemic Threatened Nationally Endangered DP SO Sp St Reef Heron Egretta sacra sacra Nativ e Threatened Nationally Endangered DP Banded Dotterel ssp Charadrius bicinctus bicinctus Endemic Threatened Nationally Vulnerable SO Sp Caspian Tern Hydroprogne caspia Nativ e Threatened Nationally Vulnerable TO Lesser Knot Calidris canutus rogersi Nativ e Threatened Nationally Vulnerable Pied Shag Phalacrocorax varius varius Endemic Threatened Nationally Vulnerable RR Wrybill Anarhynchus frontalis Endemic Threatened Nationally Vulnerable TO Eastern Bar-tailed Godw it Limosa lapponica baueri Nativ e A t Ris k Declining New Zealand Pipit ssp Anthus n. novaeseelandiae Nativ e A t Ris k Declining
Red-billed Gull Larus novaehollandiae scopulinus Nativ e A t Ris k Declining South Island Pied Oystercatcher Haematopus finschi Endemic A t Ris k Declining DP SO Spotless Crake Porzana t. tabuensis Nativ e A t Ris k Declining DP White-fronted Tern Sterna s. striata Nativ e A t Ris k Declining SO Australasian Pied Stilt Himantopus h. leucocephalus Nativ e A t Ris k Recovering St New Zealand Dabchick Poliocephalus rufopectus Endemic A t Ris k Recovering DP St New Zealand Falcon Falco novaeseelandiae Endemic A t Ris k Recovering Inc Variable Oystercatcher Haematopus unicolor Endemic A t Ris k Recovering Inc SO Australian Coot Fulica atra australis Nativ e A t Ris k Naturally Uncommon SO Sp Black Shag Phalacrocorax carbo novaehollandiae Nativ e A t Ris k Naturally Uncommon SO Sp Black-fronted Dotterel Charadrius melanops Nativ e A t Ris k Naturally Uncommon RR Little Black Shag Phalacrocorax sulcirostris Nativ e A t Ris k Naturally Uncommon Inc RR SO Sp Royal Spoonbill Platalea regia Nativ e A t Ris k Naturally Uncommon De Inc SO Australasian Gannet Morus serrator Nativ e Not Threatened Not Threatened SO Australasian Harrier Circus approximans Nativ e Not Threatened Not Threatened Bellbird ssp Anthornis melanura melanura Endemic Not Threatened Not Threatened SO Black Sw an Cygnus atratus Nativ e Not Threatened Not Threatened Inc SO Grey Teal Anas gracilis Nativ e Not Threatened Not Threatened Grey Warbler Gerygone igata Endemic Not Threatened Not Threatened Inc Little Shag Phalacrocorax melanoleucos brevirostris Nativ e Not Threatened Not Threatened Morepork Ninox n. novaeseelandiae Nativ e Not Threatened Not Threatened New Zealand Fantail (North Island ssp) Rhipidura fuliginosa placabilis Nativ e Not Threatened Not ThreatenedEF New Zealand Kingfisher Todiramphus sanctus vagans Nativ e Not Threatened Not Threatened CD Inc New Zealand Pigeon Hemiphaga novaeseelandiae Endemic Not Threatened Not Threatened Inc New Zealand Scaup Aythya novaeseelandiae Endemic Not Threatened Not Threatened New Zealand Shoveler Anas rhynchotis variegata Nativ e Not Threatened Not Threatened Paradise Shelduck Tadorna variegata Endemic Not Threatened Not Threatened Inc SO Pukeko Porphyrio m. melanotus Nativ e Not Threatened Not Threatened Shining Cuckoo Chrysococcyx l. lucidus Nativ e Not Threatened Not ThreatenedDP Silvereye Zosterops lateralis lateralis Nativ e Not Threatened Not ThreatenedSO SO Southern Black-backed Gull Larus d. dominicanus Nativ e Not Threatened Not Threatened Spotted Shag ssp Stictocarbo punctatus ssp Endemic Not Threatened Not Threatened SO Spur-w inged Plover Vanellus miles novaehollandiae Nativ e Not Threatened Not Threatened Tui Prosthemadera n. novaeseelandiae Endemic Not Threatened Not ThreatenedOL St Inc SO Welcome Sw allow Hirundo n. neoxena Nativ e Not Threatened Not Threatened Appendix 3: OSNZ Squares Full Avifauna Species List Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
SO White-faced Heron Egretta novaehollandiae Nativ e Not Threatened Not Threatened SO Arctic Skua Stercorarius parasiticus Migrant Non-resident Native Migrant SO Pomarine Skua and Arctic/Pomarine Skua spp. Stercorarius spp Migrant Non-resident Native Migrant Eastern Little Tern Sterna albifrons sinensis Migrant Non-resident Native MigrantSO Cattle Egret Ardea ibis coromanda Migrant Non- resident Native Migrant SO SO Turnstone Arenaria interpres Migrant Non-resident Native Migrant White-w inged Black Tern Chlidonias leucopterus Migrant Non-resident Native MigrantSO Little Egret Egretta garzetta immaculata Vagrant Non- resident Native Vagrant SO SO Australian Magpie Gymnorhina tibicen Introduced Introduced Introduced & Naturalised SO Sp Barbary Dove Streptopelia risoria Introduced Introduced Introduced & Naturalised SO Blackbird Turdus merula Introduced Introduced Introduced & Naturalised SO California Quail Callipepla californica Introduced Introduced Introduced & Naturalised SO Canada Goose Branta canadensis Introduced Introduced Introduced & Naturalised SO Chaffinch Fringilla coelebs Introduced Introduced Introduced & Naturalised SO Feral Goose Anser anser Introduced Introduced Introduced & Naturalised SO Feral Turkey Meleagris gallopavo Introduced Introduced Introduced & Naturalised SO Goldfinch Carduelis carduelis Introduced Introduced Introduced & Naturalised SO Greenfinch Carduelis chloris Introduced Introduced Introduced & Naturalised SO Hedge Sparrow /Dunnock Prunella modularis Introduced Introduced Introduced & Naturalised SO House Sparrow Passer domesticus Introduced Introduced Introduced & Naturalised SO Mallard Anas platyrhynchos Introduced Introduced Introduced & Naturalised SO Sp Mute Sw an Cygnus olor Introduced Introduced Introduced & Naturalised SO My na Acridotheres tristis Introduced Introduced Introduced & Naturalised SO Redpoll Carduelis flammea Introduced Introduced Introduced & Naturalised SO Ring-necked Pheasant Phasianus colchicus Introduced Introduced Introduced & Naturalised SO Rock Pigeon Columba livia Introduced Introduced Introduced & Naturalised SO Rook Corvus frugilegus Introduced Introduced Introduced & Naturalised SO Skylark Alauda arvensis Introduced Introduced Introduced & Naturalised SO Song Thrush Turdus philomelos Introduced Introduced Introduced & Naturalised SO Starling Sturnus vulgaris Introduced Introduced Introduced & Naturalised SO Yellow hammer Emberiza citrinella Introduced Introduced Introduced & Naturalised
Appendix 3: OSNZ Squares Full Avifauna Species List Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | [Subject]
Appendix 4: Full List of Avifauna Species Recorded During Surveys of the Ngaruroro River
SPECIES CONSERVATION STATUS - Roberston et al. 2017 White heron Ardea modesta Native Threatened Nationally Critical Reef heron Egretta sacra sacra Native Threatened Nationally Endangered Australasian bittern Botaurus poiciloptilus Native Threatened Nationally Critical Grey duck Anas superciliosa Native Threatened Nationally Critical Caspian tern Hydroprogne caspia Native Threatened Nationally Vulnerable Banded dotterel Charadrius bicinctus bicinctus Endemic Threatened Nationally Vulnerable Shore plover Thinornis novaeseelandiae Endemic Threatened Nationally Critical Wrybill Anarhynchus frontalis Endemic Threatened Nationally Vulnerable Black-billed gull Larus bulleri Endemic Threatened Nationally Critical Black-fronted tern Chlidonias albostriatus Endemic Threatened Nationally Endangered Black shag Phalacrocorax carbo novaehollandiae Native At Risk Naturally Uncommon Little black shag Phalacrocorax sulcirostris Native At Risk Naturally Uncommon Royal spoonbill Platalea regia Native At Risk Naturally Uncommon Spotless crake Porzana tabuensis Native At Risk Declining Pied stilt Himantopus leucocephalus Native At Risk Recovering Black-fronted dotterel Charadrius melanops Native At Risk Naturally Uncommon Eastern bar-tailed godwit Limosa lapponica baueri Native At Risk Declining Red-billed gull Larus novaehollandiae scopulinus Native At Risk Declining White-fronted tern Sterna striata Native At Risk Declining New Zealand pipit Anthus novaeseelandiae Native At Risk Declining New Zealand dabchick Poliocephalus rufopectus Endemic At Risk Recovering New Zealand falcon Falco novaeseelandiae Endemic At Risk Recovering Marsh crake Porzana pusilla affinis Endemic At Risk Declining South Island pied oystercatcher Haematopus finschi Endemic At Risk Declining Variable oystercatcher Haematopus unicolor Endemic At Risk Recovering New Zealand dotterel Charadrius obscurus aquilonius Endemic At Risk Recovering New Zealand fernbird Bowdleria punctata vealeae Endemic At Risk Declining Australasian gannet Morus serrator Native Not Threatened Not Threatened Little shag Phalacrocorax melanoleucos brevirostris Native Not Threatened Not Threatened White-faced heron Egretta novaehollandiae Native Not Threatened Not Threatened Black swan Cygnus atratus Native Not Threatened Not Threatened Grey teal Anas gracilis Native Not Threatened Not Threatened Australasian shoveler Anas rhynchotis variegata Native Not Threatened Not Threatened Australasian harrier hawk Circus approximans Native Not Threatened Not Threatened Pukeko Porphyrio melanotus Native Not Threatened Not Threatened Spur-winged plover Vanellus mile novaehollandiae Native Not Threatened Not Threatened Black-backed gull Larus dominicanus Native Not Threatened Not Threatened Shining cuckoo Chrysococcyx lucidus Native Not Threatened Not Threatened Morepork Ninox novaeseelandiae Native Not Threatened Not Threatened Sacred kingfisher Todiramphus sanctus vagrans Native Not Threatened Not Threatened Welcome swallow Hirundo neoxena Native Not Threatened Not Threatened North Island fantail Rhipidura fuliginosa placabilis Native Not Threatened Not Threatened Silvereye Zosterops lateralis lateralis Native Not Threatened Not Threatened Red knot Calidris canutus rogersi Native Non-resident Native Vagrant Spotted shag Stictocarbo punctatus Endemic Not Threatened Not Threatened Paradise shelduck Tadorna variegata Endemic Not Threatened Not Threatened Kereru Hemiphaga novaeseelandiae Endemic Not Threatened Not Threatened Grey warbler Gerygone igata Endemic Not Threatened Not Threatened
Appendix 4: Full List of Avifauna Species Recorded During Surveys of the Ngaruroro River Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
New Zealand bellbird Anthornis melanura Endemic Not Threatened Not Threatened Tui Prosthemadera novaeseelandiae Endemic Not Threatened Not Threatened Feral goose Anser anser Introduced Introduced Introduced & Naturalised Canada goose Branta canadensis Introduced Introduced Introduced & Naturalised Mallard duck Anas platyrhynchos Introduced Introduced Introduced & Naturalised Ring-necked pheasant Phasianus colchicus Introduced Introduced Introduced & Naturalised California quail Callipepla californica Introduced Introduced Introduced & Naturalised Rock pigeon Columba livia Introduced Introduced Introduced & Naturalised Skylark Alauda arvensis Introduced Introduced Introduced & Naturalised Dunnock Prunella modularis Introduced Introduced Introduced & Naturalised Common blackbird Turdus merula Introduced Introduced Introduced & Naturalised Song thrush Turdus philomelos Introduced Introduced Introduced & Naturalised Australian magpie Gymnorhina tibicen Introduced Introduced Introduced & Naturalised Rook Corvus frugilegus Introduced Introduced Introduced & Naturalised Common starling Sturnus vulgaris Introduced Introduced Introduced & Naturalised Common myna Acridotheres tristis Introduced Introduced Introduced & Naturalised House sparrow Passer domesticus Introduced Introduced Introduced & Naturalised Chaffinch Fringilla coelebs Introduced Introduced Introduced & Naturalised European greenfinch Carduelis chloris Introduced Introduced Introduced & Naturalised European goldfinch Carduelis cardeulis Introduced Introduced Introduced & Naturalised Common redpoll Carduelis flammea Introduced Introduced Introduced & Naturalised Yellowhammer Emberiza citrinella Introduced Introduced Introduced & Naturalised Cattle egret Ardea ibis coromanda Migrant Non-resident Native Migrant Pacific golden plover Pluvialis fulva Migrant Non-resident Native Migrant Ruddy turnstone Arenaria interpres Migrant Non-resident Native Migrant Red-necked stint Calidris fuficollis Migrant Non-resident Native Migrant Sharp-tailed sandpiper Calidris acuminata Migrant Non-resident Native Migrant Arctic skua Stercorarius parasiticus Migrant Non-resident Native Migrant Eastern little tern Sternula albifrons sinensis Migrant Non-resident Native Migrant White-winged black tern Chlidonias leucopterus Migrant Non-resident Native Migrant Little egret Egretta garzetta Migrant Non-resident Native Migrant Intermediate egret Ardea intermedia Migrant Non-resident Native Migrant Gull-billed tern Gelochelidon nilotica Migrant Non-resident Native Migrant Pectoral sandpiper Calidris melanotos Migrant Non-resident Native Migrant Curlew sandpiper Calidris ferruginea Migrant Non-resident Native Migrant
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Appendix 5: Assemblage of Avifauna Species Recorded During Surveys of the Ngaruroro River and Surrounds1
Species Categorisation Species (n) Total (%) Native 32 38.6 Endemic 18 21.7 Introduced 20 24.1 Migrant 8 9.6 Vagrant 5 6
Total 83
1 (Stephenson, 2009)
Appendix 5: Assemblage of Avifauna Species Recorded During Surveys of the Ngaruroro River and Surrounds1 Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Appendix 6: Historic Avifauna Survey Numbers of the Ngaruroro River of ‘more common’ Threatened and at Risk Species1.
Year Species 1962 1967 1972 1984 1986 1993 20092 Black shag 18 14 10 3 5 3 - Little black shag 0 16 1 1 _ 0 - Little shag 9 24 7 Present 12 4 - Grey duck 0 23 0 0 0 0 - SIPO 0 0 0 10 8 8 5+ Wrybill 0 0 0 0 1 0 - Banded dotterel 514 246+ 216+ 438 480 570 253 Black-fronted dotterel 39 96 134 127 145 137 53 Australasian pied stilt 323 181+ 173+ 461 220 270 163 Black-billed gull 0 16 16 25 8 15 153
1 Source: (Maxwell et al., 1993; Parrish, 1988; Stephenson, 2009)
2 The 2009 numbers are not directly comparable to the other years as not all of the Lower Ngaruroro River was surveyed (only the sections between Otamauri Stream (Pigsty Swamp) to Mangatahi (11.7 km) and Mangatahi to Maraekakaho (4.7 km) were surveyed).
Appendix 6: Historic Avifauna Survey Numbers of the Ngaruroro River of ‘more common’ Threatened and at Risk Species1. Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Appendix 7: Water quality monitoring locations
River Monitoring location Easting Northing Monitoring years Regional rivers Aropaoanui River Sideless Bridge 2853243 6207289 1995 - 2010 Clive River U/s Whakatu rail 2842951 6171188 1985 - 2010 bridge d/s Raupare Esk River Berry Road 2837736 6212481 1994 - 2010 Waipunga Bridge 2839017 6195088 1985 - 2010 Mohaka River Glenfalls 2823979 6218769 1989 - 2012 Raupunga 2867237 6228523 1989 - 2012 Willowflat 2851834 6237001 1997 - 2010 Porangahau River SH52 2814330 6094858 1995 - 2010 Tukituki River Ashcott Road 2796308 6135724 1995 - 2011 Black Bridge 2847566 6170374 1995 - 2011 Red Bridge 2846597 6158135 1989 - 2012 Shag rock 2826307 6133014 1998 - 2011 Tutaekuri River Brookfields Bridge 2843370 6174562 1986, 1995 - 2010 Waikari River Glenbrook Road 2857492 6221227 2000 - 2010 Wairoa River d/s waste water 2892303 6229029 1995 - 2010 discharge Rail bridge 2890580 6235404 1995 - 2010
National Rivers Ashley River At Gorge Bridge 2447345 5775206 2007 - 2011 SH1 2484800 5770000 2002 - 2011 Clutha River Balclutha 2258996 5436246 1989 - 2012 Millers Flat 2230200 5498800 1989 - 2012 Grey River Dobson 2369993 5860128 1989 - 2012 SH7 Ikamatua 2400500 5879200 1990, 1998 - 2006 Kaituna River Paengaroa 2808600 6368200 1990 - 1999, 2005 - 2011 Te Matai Rail Bridge 2806100 6373600 1990 - 2011 Manawatu River Opiki Bridge 2719400 6082740 1989 - 2012 Teachers College 2733100 6089200 1989 - 2012 u/s PNCC STP 2729250 6087751 2007 - 2012 u/s PPCS Shannon 2713351 6072811 2007 - 2012 Whirokino Boat Ramp 2702200 6074700 2000 - 2012 Mataura River 200 m d/s Mataura 2190634 5437518 1978 - 1988, 1995 - 2012 Bridge Gore 2196661 5448847 2000 - 2012 Gorge Road 2182700 5402300 1978 - 1986, 1995 - 2012 Mataura Island Bridge 2184900 5415800 1989 - 2012 Otamita Bridge 2188000 5458400 1975 - 1986, 1995 - 2012 Seaward Downs 2186569 5416006 1989 - 2012 Mokau River Awakau Road 2660100 6278500 1993 - 2011 Mangaokewa Road 2709600 6301700 1993 - 2011 Totoro Road recorder 2675900 6290700 1993 - 2011 Rakaia River At North Channel – 2432934 5718200 2002 - 2011 SH1 At The Gorge < The 2401484 5742398 2002 - 2011 Bridge Rangitaiki River Te Teko 2843629 6344416 1989 - 2012 Thornton Bridge 2849930 6357290 1990 - 1996 Rangitikei River Kakariki 2718305 6117218 1989 - 2012 McKelvie 2703400 6098600 2006 - 2012 Onepuhi 2720100 6122200 2005 - 2012 u/s Bulls STP 2712800 6110300 2008 - 2012 Ruamahanga River Gladstone Bridge 2731225 6012049 2003 - 2012 McLays 2728161 6047524 2003 - 2012 Mt Bruce 2729914 6046092 1989 - 2012 Pukio 2707855 5992730 2003 - 2012 Te Ore Ore 2735588 6024740 2003 – 2012 Waihenga 2714559 5998412 1989 - 2012 Wardells 2734728 6019152 1989 - 2012
Appendix 7: Water quality monitoring locations Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
River Monitoring location Easting Northing Monitoring years Waiau River Duncraigen Road 2096068 5496558 2002 - 2012 Sunnyside 2093426 5476407 1994 - 1995, 1998 - 2012 Tuatapere 2099363 5439848 1989 - 2012 Waimakariri River At End of Ferry Road 2484371 5757548 1996 - 1999, 2002 - 2011 At Stewarts Gully 2483406 5756278 2002 - 2011 Yacht Club Gorge 2433142 5760479 1989 - 2012 Old Highway Bridge 2481000 5754000 1989 - 2012 Wairau River Tuamarina 2590635 5973743 1989 - 2012 Waitaki River Kurow 2308015 5608817 1989 - 2012 SH1 Bridge 2360000 5585000 1989 - 2012 Whakatane River Pekatahi Bridge 2859700 6342700 1990 - 2011 Ruatoki Bridge 2860800 6332400 1990 - 1999, 2003 - 2004, 2008 - 2009, 2011
Appendix 7: Water quality monitoring locations Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
Boffa Miskell Ltd | Aquatic ecology of the lower Ngaruroro River | Ecological assessment and comparison at a local, regional and national scale
ATTACHMENT 2 - NIWA MAP OF TORRENT FISH DISTRIBUTION
ATTACHMENT 3 - SCORING TABLE FROM HUGHEY ET AL 2012 – LABELLED “SIGNIFICANCE ASSESSMENT CALCULATIONS FOR NATIVE FISH LIFE IN THE HAWKE’S BAY”