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Kukuriki Reef Intertidal Ecology Survey 2025
A Rūnanga-led project documenting the marine biodiversity of a culturally significant reef in north Taranaki
01
Prepared by
Jesu Valdes, Lead Scientist, Taranaki Regional Council
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Reviewed by
Fern Kumeroa, Taiao Team Te Runanga o Ngāti Mutunga
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Community Participation
18 whānau members and community representatives attended the survey
Introduction
In 2018, SLR Consulting NZ Limited was engaged by OMV Taranaki Limited to undertake a marine ecological inspection at Kukuriki Reef, a site culturally important to Ngāti Mutunga in north Taranaki. Ngāti Mutunga selected this reef due to its significance as a mahinga kai site, particularly for kuku/kūtai (New Zealand green-lipped mussel; Perna canaliculus).
The initial intertidal assessment was carried out on 25 November 2018 during spring low tide, with Ngāti Mutunga whānau present to select the reef location. This qualitative survey identified species present and developed recommendations for future monitoring as part of Ngāti Mutunga's annual environmental monitoring programme.
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2018
Initial qualitative survey by SLR identifies 19 species
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2019
SLR report recommends quantitative monitoring approach
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2025
First quantitative survey using TRC methodology finds 26 species
Taking these recommendations into consideration, a quantitative intertidal ecological survey following Taranaki Regional Council's rocky shore method was conducted on 6 November 2025 as part of Ngāti Mutunga's coastal Mauri Compass programme. This work supports Ngāti Mutunga's aspirations to provide for their relationship with the coast and ensure coastal resources are restored and protected.
Taranaki Coast Marine Environment
Rocky reefs dominate the intertidal zone of the Taranaki coastline. Around the ring plain, these reefs are largely formed from lahar (volcanic derived) materials consisting of andesite cobbles and boulders bound within an ash-type matrix. Selective erosion of the weaker matrix leaves harder cobbles and boulders to form large platform reefs.
Although typically low in relief, these reefs can be considerable in extent. The reefs off the Waitara coastline extend as far as five kilometres offshore. Most intertidal reefs are comprised of lahar conglomerate bedrock, andesitic boulders, rock pools and occasional sand patches.
Complex Habitat
Rocky shores provide three-dimensional environments with cracks and crevices offering shelter for numerous marine species
High Energy
Exposed to persistent south-westerly winds from the Tasman Sea and dominant westerly waves
Dynamic Conditions
Considerable sand movement and turbid conditions from river inputs and cliff erosion
Kukuriki Reef
Kukuriki Reef is located approximately 2 km southwest of the Waiiti Beach Camp. It is the only rocky feature in an otherwise sandy beach, with a backdrop of large papa and sandstone cliffs along the upper shore. Large numbers of NZ green-lipped mussels (P. canaliculus) are present on the reef and harvested by Ngāti Mutunga and the wider local community.
Unique Characteristics
  • Very small reef confined to limited area
  • Bound by sand on either side
  • Significant mussel bed coverage reaching up to 100% in some areas
  • Different from other Taranaki reefs in size and composition
Figure 1 Location of Kukuriki Reef in relation to Waiiti Beach Camp (source: SLR, 2019)

Cultural Significance: Kukuriki Reef serves as an important mahinga kai site for Ngāti Mutunga, providing traditional food resources and maintaining cultural connections to the coast.
Intertidal Ecology Survey Method
Taking into consideration SLR's 2019 recommendations, the quantitative intertidal survey method used by Taranaki Regional Council was selected. This robust methodology is widely used by regional councils throughout Aotearoa as part of State of the Environment (SoE) Monitoring.
Site Selection
Transect location identified using GPS coordinates and reference photographs to ensure repeatability
Transect Setup
50m transect laid parallel to shore at approximately 0.6m above chart datum
Block Establishment
Five 5m x 3m blocks established along transect with five random 0.5m² quadrats per block
Species Assessment
Percentage cover estimated for algae and encrusting animals; individuals >3mm counted and identified
The rocky shore component of the SoE monitoring programme for Taranaki was initiated in 1994/95 and has continued annually since. Six representative reef sites are surveyed twice yearly in spring and summer.
Survey Implementation at Kukuriki Reef
Survey Details
  • Date: 6 November 2025
  • Time: 17:00 NZDT
  • Low Tide: 0.28m at 16:53
  • Weather: Fine with light offshore breeze
  • Total Quadrats: 25 random samples
The survey area was selected by Ngāti Mutunga, focusing on areas with significant healthy mussel beds while excluding taller vertical reef formations.
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Start Rock
NZTM E:1726494 N:5689163
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Transect Direction
Parallel to water line, 50m length
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End Rock
NZTM E:1726470 N:5689121
The method previously described was applied to Kukuriki Reef for the first time on 6 November 2025, marking the beginning of long-term quantitative monitoring at this culturally significant site.
Ecological Indices
Survey data are used to calculate two key ecological indices: species richness and the Shannon-Wiener diversity index (H'). Species richness is a straightforward count of the total number of different species in a particular area.
Shannon-Wiener Index
This mathematical tool combines both richness and evenness (the relative abundance of each species) into a single number. The value increases as both the number of species and the evenness of their populations increase.
Greater Shannon-Wiener Index = Greater diversity
100%
High Diversity
Many species in even proportions
50%
Moderate Diversity
Some species dominance
25%
Low Diversity
Few species or one dominant
Diverse ecological communities are composed of a high number of species present in relatively even proportions. These communities often include a high number of species within each functional group (primary producers, grazers, suspension feeders, predators) and are generally more resilient to stressors and disturbances.

Sand Cover Impact: The level of sand cover at a site can significantly impact species richness and diversity. Studies in Taranaki show that sand cover is the main driving force behind variability in these ecological parameters.
Understanding Diversity and Sand Impact
High Diversity Communities
Composed of many species in relatively even proportions, with representatives from multiple functional groups. These communities show greater resilience to environmental stressors.
Low Diversity Communities
Characterized by fewer species or where one species is disproportionately abundant. These communities may be more vulnerable to disturbances.
Sand Cover Threshold Effects
While reef communities may tolerate some level of sand cover, above a certain threshold the community becomes impacted. Once this threshold is exceeded, the number of species declines before eventually reaching low values at high percentages of sand cover.
Studies in Taranaki have demonstrated that sand cover is the main driving force behind variability in species richness and diversity at a site.
Survey Results: Species Discovery
26
Total Species
Found during 2025 survey
12
Algal Species
Including green, brown, and red algae
14
Animal Species
Including barnacles, gastropods, and bivalves
+37%
Increase
From 19 species in 2019 to 26 in 2025
This survey showed a significant increase in the number of species identified compared to SLR's 2019 report, which found 19 species total (4 algal and 15 animal species). The 2025 survey using TRC's quantitative method identified 26 species (12 algal and 14 animal).
Green Algae
3 species of Chlorophyta including sea lettuce and gutweed
Brown Algae
3 species of Phaeophyceae providing habitat structure
Red Algae
6 species of Rhodophyta including coralline paint
Animal Species Diversity
Invertebrate Groups Found
  • Barnacles (3 species): Beaked, columnar, and plicate barnacles
  • Gastropods (3 species): Radiate limpet, spotted whelk, cart-rut shell
  • Bivalves (2 species): Green-lipped mussel, little black mussel
  • Chitons (3 species): Giant, snakeskin, and rainbow chitons
  • Other: Blue tube worm, pillbox crab, orange sponge
Dominant Species
NZ green-lipped mussel (Perna canaliculus) was the only abundant species, with 41-100% coverage
Present Species
All other algal and animal species were classified as present (<50 individuals or <20% coverage)
The lowest number of species found in surveyed quadrats was zero, occurring when sand coverage was 100%. The highest number observed in a single quadrat was fourteen species.
Ecological Parameters at Kukuriki Reef
The survey data revealed important patterns in species distribution and diversity at Kukuriki Reef. Mean values per quadrat showed moderate sand coverage and relatively low species richness compared to other Taranaki reefs.
Algae Diversity (H')
0.387 ± 0.300
Animal Diversity (H')
0.194 ± 0.247
Combined Diversity (H')
0.328 ± 0.324
Comparison with Regional Reefs
For comparison, the rocky shore sites monitored by Taranaki Regional Council as part of State of the Environment monitoring show much higher values for ecological parameters. Data from six sites studied between 1994 and 2024 provide important context for understanding Kukuriki Reef's unique characteristics.
Kukuriki Reef presents significantly lower values than all six TRC monitoring sites, reflecting its unique environmental conditions and limited habitat availability.
Discussion: Method Effectiveness
Survey Success
This survey method proved effective at providing quantitative data on species richness and diversity at the mussel beds area of Kukuriki Reef. It successfully trialled the methodology utilized by Taranaki Regional Council at other rocky reefs in the region for the first time at this culturally significant site.
Focused Approach
The 2025 survey concentrated efforts on one area of outcrops significant to Ngāti Mutunga due to stable mussel beds
Increased Detection
More time spent in the mussel bed area resulted in identification of 26 species versus 19 in 2019
Standardized Data
Quantitative method allows detection of changes and trends if repeated annually
The increase in species found (from 19 in 2019 to 26 in 2025) can be explained by the difference in methodology. The 2019 survey searched a wider area without a standardized approach, while the 2025 survey used TRC's quantitative method for a more targeted search.
Understanding Kukuriki's Unique Environment
When comparing ecological parameters to TRC's State of the Environment monitoring sites, Kukuriki Reef presents significantly lower values. This was expected due to the coastline and reef area being restricted by habitat and susceptible to sand influence from being a highly exposed coastline.
Limited Substrate
Restricted papa and sandstone outcrops provide limited habitat for hard-substrate dependent species
High Exposure
More exposed and erosion-prone than other Taranaki reefs, facing persistent wave action
Sand Impact
High sand deposition causes scour and burial, reducing diversity through physiological stress
Lower Diversity
Fewer species can survive in these challenging conditions compared to more sheltered reefs
Highly heterogeneous sites like Mānihi Reef, characterized by a wide range of different substrates with plenty of cobbles, rocks, and boulders, present a wider range of habitats for species to colonize and inhabit, resulting in higher species richness and diversity values.
Sand Effects on Reef Communities
Sand deposition has been shown to have profound effects on intertidal hard-shore communities in Taranaki. The presence of high quantities of sand results in reduced diversity due to two primary mechanisms: sand scour and temporary sand burial.
Sand Scour
Impacts reef organisms causing removal from substrate, physiological stress, and increased metabolic demand
Sand Burial
Results in reduced light, oxygen and food availability for buried organisms
Community Impact
Inundation events cause significant reductions in species richness and diversity
47.6%
Mean Sand Cover
At Kukuriki Reef
100%
Maximum Coverage
Zero species found
Studies by Walsby (1982), Airoldi et al. (1996), and Howse et al. (2000) have documented these effects. Sand scour and burial create challenging conditions that only the most resilient species can tolerate, explaining the lower diversity observed at sand-influenced sites like Kukuriki Reef.
The Role of Green-Lipped Mussels
Despite the challenging conditions, the pockets of hard substrate created by remaining papa and sandstone outcrops provide important habitat. The NZ green-lipped mussel was found to be the most abundant species, forming dense beds in the surveyed area.
Habitat Creation
Mussel beds provide structure for other species
Water Filtration
Filter feeding improves water quality
Food Source
Provide nutrition for predators and scavengers
Resource Control
Structure environment and resource availability
Protection
Offer shelter from wave action and predation

Ecosystem Engineers: NZ green-lipped mussels are considered "ecosystem engineers" because they create habitat, filter water, and provide food, thereby controlling the availability of resources and structuring their environment.
During the survey, several species were found living amongst (cart-rut shell) or on the mussels (columnar barnacle), demonstrating the mussel beds' importance as habitat providers in this limited reef environment.
Habitat Comparison: Kukuriki vs Mānihi
Kukuriki Reef
  • Limited papa and sandstone outcrops
  • Surrounded by extensive sand
  • Low substrate heterogeneity
  • Fewer habitat niches available
  • Mean richness: 5.56 species/quadrat
Mānihi Reef
  • Wide range of substrate types
  • Abundant cobbles, rocks, boulders
  • High substrate heterogeneity
  • Multiple habitat niches
  • Mean richness: 20.16 species/quadrat
The stark difference in habitat complexity between these sites explains the variation in species richness and diversity. Highly heterogeneous sites present a wider range of different habitats for species to colonize and inhabit, supporting more diverse communities.
Substrate Diversity
More substrate types = more ecological niches = higher species diversity
Habitat Stability
Stable substrates support permanent residents and complex food webs
Acknowledgements
We extend our sincere thanks to Te Rūnanga o Ngāti Mutunga for inviting us to participate in this activity as part of their coastal Mauri Compass mahi, and to all whānau who attended.
We acknowledge and greatly appreciate the manaakitanga, kōrero, and commitment shown, not only through participation in the rocky shore survey methods used by Taranaki Regional Council, but also through the sharing of experiences and mātauranga Māori.
Partnership
Collaborative approach combining scientific methodology with cultural knowledge and values
Community Engagement
Active participation from 18 whānau members and community representatives
Future Collaboration
Building and strengthening relationships for ongoing environmental monitoring
This was a highly valuable activity, and we look forward to continuing to build and strengthen this relationship through future monitoring and conservation efforts at Kukuriki Reef.
Recommendations
Taking into consideration the results from SLR's 2019 report and this quantitative ecological survey carried out for the first time in 2025 at Kukuriki Reef, the following recommendations are made for ongoing monitoring and management:
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Annual Monitoring
Ngāti Mutunga undertakes a survey in the same location following this methodology once per year as part of long-term monitoring at Kukuriki Reef
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Reference Library
Build up a reference library with clear, high-resolution species photos from different angles of each animal and algae found in quadrats
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Trend Analysis
Continue to estimate ecological metrics of species richness and diversity to compare parameters over time and detect trends and changes
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Mussel Bed Mapping
Conduct aerial imagery and/or mussel bed mapping regularly to detect changes in the extent of mussel coverage at Kukuriki Reef
Safety and Timing Recommendations
Tidal Requirements
Schedule surveys only for tides ≤0.3m during favorable weather conditions, as the area is exposed for a brief period
Weather Conditions
Do not attempt monitoring if adverse weather conditions are present such as strong onshore winds or large swell
Tidal Window
Consider safe return time to Waiiti Camp when planning survey duration
Personal Protective Equipment
  • Appropriate footwear for rocky terrain
  • Diving gloves to protect hands
  • Sun hat and sunscreen
  • Additional change of clothes
  • Adequate hydration supplies

Safety First: Kukuriki Reef is a hazardous site with limited safe access time. Always prioritize team safety over data collection and be prepared to postpone surveys if conditions are unfavorable.
References
Primary Sources
  • Airoldi, L., Fabiano, M., Cinelli, F. 1996. Sediment deposition and movement over a turf assemblage in a shallow rocky coastal area of the Ligurian Sea. Marine Ecology Progress Series 133: 241-251.
  • Howse, B.P.S., Black, K.P., Cole, R.G., & McComb, P.J. 2000. Port Taranaki Dredging consent renewal studies. Report 3: The relationship of sediment flux to abundance and sizes of pāua and kina on New Plymouth reefs. Department of Earth Sciences, University of Auckland.
  • SLR, 2019. Kukuriki Reef Intertidal Inspection. SLR Ref: 740.10004.00400‐R01. Version No: ‐v1.0.
Regional Council Reports
  • Taranaki Regional Council. 1991. Taranaki Coastal Marine Area, Resource Description and Management Issues. Taranaki Regional Council, Stratford, New Zealand.
  • TRC, 2025. Rocky Shore State of the Environment Monitoring Report 2019-2024 Technical Report 2025-34.
  • Walsby, J.R. 1982. Marine ecological baseline programme NZSFC Synthetic Petrol Plant Motunui.
Appendix I: Algal Species Identification Guide
This identification guide provides visual references for the 12 algal species found during the November 2025 survey at Kukuriki Reef. Clear photographs from multiple angles assist with accurate species identification during future monitoring.
Codium fragile
Common name: Dead man's fingers
Type: Green algae (Chlorophyta)
Characteristics: Spongy, finger-like branches
Coralline Paint
Type: Encrusting red algae
Characteristics: Pink to purple crust covering rock surfaces
Gelidium caulacantheum
Common name: Jellyweed
Type: Red algae (Rhodophyta)
Characteristics: Small, branching red fronds
Ulva sp.
Common name: Sea lettuce
Māori name: Rimu
Type: Green algae
Characteristics: Bright green, sheet-like
When photographing algae for identification, capture the full specimen showing fronds and holdfast from multiple angles. Include a scale reference when possible.
Appendix I: Animal Species Identification Guide
This section provides visual references for the 14 animal species found during the survey. Accurate identification requires clear photographs from both dorsal (top) and ventral (underneath) views for gastropods and other mobile species.
Perna canaliculus
Common name: NZ green-lipped mussel
Māori name: Kuku/Kūtai
Abundance: Abundant (41-100% coverage)
Significance: Ecosystem engineer, culturally important
Cellana radians
Common name: Radiate limpet
Māori name: Ngākihi
Characteristics: Distinctive radial pattern on shell
Chamaesipho columna
Common name: Column barnacles
Māori name: Tiotio/Koromaungaunga
Characteristics: Tall, columnar shape
Plaxiphora obtecta
Common name: Giant chiton
Māori name: Haka-hiwihiwi
Characteristics: Large, eight-plated mollusk
Appendix II: Additional Identification Resources
The following resources provide comprehensive identification guides for marine species found in New Zealand's intertidal zones. These are valuable references for building identification skills and confirming species during surveys.
Rocky Shore Guide – Northern NZ
University of Otago comprehensive guide to northern New Zealand rocky shore species
NIWA Identification Guides
Series of specialized guides covering specific taxonomic groups:
  • Adorable Anemones
  • Beloved Barnacles
  • Coastal Crabs
  • Beautiful Browns (Brown algae)
  • Splendid Sponges (Intertidal & Subtidal)
  • Super Sea Slugs
iNaturalist NZ
Community science platform for recording and identifying New Zealand biodiversity

Building Expertise: Regular use of these identification resources will improve survey accuracy and help build a comprehensive reference library specific to Kukuriki Reef.
Moving Forward: Long-Term Monitoring
This inaugural quantitative survey at Kukuriki Reef marks the beginning of a long-term monitoring programme that will track ecological changes over time. The baseline data collected in 2025 provides a foundation for detecting trends and assessing the health of this culturally significant site.
1
2025 Baseline
First quantitative survey establishes baseline data: 26 species, mean richness 5.56, diversity 0.328
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Annual Monitoring
Repeat surveys detect changes in species composition, abundance, and diversity over time
3
Trend Analysis
Multi-year data reveals patterns and helps identify environmental stressors or improvements
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Adaptive Management
Monitoring results inform conservation decisions and management strategies
Partnership Success
This project demonstrates the value of combining scientific methodology with mātauranga Māori and community engagement. The collaborative approach ensures monitoring is culturally appropriate, scientifically rigorous, and sustainable long-term.
1
Baseline Year
Foundation established
25
Quadrats
Surveyed annually
26
Species
Currently documented
Through continued monitoring and partnership, we can ensure Kukuriki Reef remains a healthy mahinga kai site for future generations of Ngāti Mutunga.