MEASURING THE BASELINE HEALTH OF PIPI IN WHANGĀREI

Results from a two-year research project in partnership with Patuharakeke hapū

Mair Bank on a fine day looking towards Mount Manaia, three people gathering pipi in centre. The Biosecurity and Patuharakeke Te Iwi Trust Board logo are in the top corners

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Ko Manaia te maunga Ko Te Rerenga Parāoa te moana Ko Takahiwai te whenua Ko Rangiora te tūpuna whare Ko Patuharakeke te hapū Tihei mauri ora

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Names for pipi

Local name: kōkota| Common name: pipi | Latin name: Paphies australis

This species of shellfish is commonly known as pipi, but is known locally as both kōkota and pipi. For simplicity, the name pipi has been used in this report.

Project background

In 2019, the Patuharakeke Taiao Unit reported a pipi mass mortality in Whangārei. The event was reported to Biosecurity New Zealand via the 0800 exotic pests and diseases hotline.

In response, Biosecurity New Zealand scientists and Patuharakeke collected pipi from Mair Bank to test for exotic diseases. While no exotic diseases were found, some interesting bacteria were present. However, it was unknown if these bacteria were good or bad for the pipi.

Government funding was sought for further scientific research. This was successful, and in 2020, a two-year study was launched in partnership with the Patuharakeke Taiao Unit.

The project aimed to create a baseline health study of four pipi populations in Whangārei Harbour.

What is a baseline health study?

This is a kind of scientific study. It provides researchers a snapshot of the current situation and a starting point for being able to monitor the health of a particular species.

There is currently little existing data on what 'normal' health looks like for wild shellfish in New Zealand. The goal of this study was to start filling knowledge gaps and collect benchmark data for pipi in the affected areas.

About pipi in Whangārei

The importance of pipi

Pipi are considered a taonga (treasure) by Māori. In Whangārei, they have long been an important food source for local communities and have widespread cultural significance to the local hapū, Patuharakeke.

Black and white simple map which shows traditional Māori place names around the Whangārei Harbour

“Many of our whanaunga (relatives) grew up eating pipi several times a week, which supplemented the larders of our generally lower income whānau. Pipi beds were once abundant mahinga mātaitai (food gathering places) and it is central to our role as tangata tiaki to understand the state of health of these mahinga kai, and work to restore these sites to their former abundance." — Patuharakeke Taiao Unit       

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Patuharakeke have whakapapa connections to the moana and have occupied the coastal settlement of Takahiwai for many centuries. Te Rerenga Parāoa is recognised as a nationally significant ecosystem, serving as a habitat for many species which have supported the livelihoods of tangata whenua.

Pipi numbers an established concern

The reduced number of pipi in the rohe was already concerning before the mass mortalities reported in 2019.

The following provides a brief timeline of events, including closures to help protect the fishery.

2009

Patuharakeke Rohe Moana is mandated (under the Fisheries (Kaimoana Customary Fishing) Regulations 1998) as kaitiaki for the rohe moana and customary fisheries.

2011

Patuharakeke requests under section 186a of the Fisheries Act 1996 for the temporary closure of the pipi fishery at Marsden bank, approved by the Ministry of Fisheries (now MPI) and renewed in 2013.

2014

Ministry of Fisheries closes the pipi fishery indefinitely (under section 11 of the Fisheries Act 1996).

2017

Patuharakeke put forward a further request under section 186a seeking closure of both Marsden and Mair Bank to all shellfish harvesting. This was approved by MPI in 2018. The closure has been rolled over in 2020 and 2022.

2018

A customary rāhui was put in place to accompany and add strength and tikanga to the section 186a closures.

2019

Biosecurity New Zealand's animal health investigations ruled out the presence of any exotic diseases in the pipi.

To date, no singular reason has been found to explain the decline.

Pou rāhui (carved post) - a tall, black, wooden post featuring white and blue details in a ring towards the top.

Environmental changes to the rohe over time

Over the last hundred years there have been many changes to Te Rerenga Parāoa and the surrounding land. These include:   

  • industrialisation (e.g. the port, the refinery)  
  • land use changes  
  • subdivisions 
  • pressure on fisheries (e.g. increased recreational harvesting of kaimoana and commercial harvesting of pipi)
  • El Niño and La Niña fluctuations
  • climate change

Collectively, these pressures have influenced changes in the overall health of the harbour and associated mahinga kai.

Select a location on the map below to learn more (expand the map to full screen for easy navigation):

Changes to the environment in Te Rerenga Parāoa - Whangārei Harbour

Pipi biology & ecology

Pipi are surf clams that are native to Aotearoa. They are an important food source and taonga to the communities who live close to them.

Pipi also play an important role in their wider ecosystem. They provide many benefits for the ocean and environment, such as:

  • improving water quality through filtration as they feed
  • reducing shoreline erosion
  • keeping the estuary environment stable.

Pipi anatomy

The picture below demonstrates different parts of pipi. Click on the red icons to find out more about the anatomy of a pipi.

How we did the research

A collaborative research effort

The research was a collaborative effort between Patuharakeke and Biosecurity New Zealand scientists. Both groups shared their respective knowledge to try and better understand what is happening to the pipi.

Patuharakeke and Biosecurity New Zealand collected pipi every 3 months, which were taken to the Biosecurity lab for examination. The condition of the pipi was recorded throughout the seasons.

The partnership provided opportunities for several hui at Takahiwai Marae and in Wellington. Tamariki from Ruakākā School and Bream Bay College were invited to hui. Ari and Xzavier, from the Patuharakeke Te Taiao Unit, had the opportunity to visit the NIWA Marine collection, and the Biosecurity New Zealand Animal Health Lab.

Various images from collection sites and workshops

Research methods

Pipi were collected for 2 years, every 3 months, from 4 locations.

A combination of methods were used to analyse the pipi – each described below. Collectively, they've helped us better understand the general health of the pipi and monitor bacteria levels throughout the year.

Step 1: Observational research

Recording what we see in the natural environment

Taking clear observations of the surrounding environment, and engaging with the community are essential to understand any changes that could be impacting the health of marine organisms.

On the left side, a person stands knee deep in the river taking notes. On the right, water and sand is discoloured orange on the river bank

Step 2: Culturing bacteria

Taking a bacteria sample and growing it in a laboratory

This method allows us to identify what bacteria is present in shellfish. By taking a swab of the animal and growing the swab on media (different nutrients) we can find out what is going on inside the pipi. It is important to know what bacteria are present, as some may be harmful.

A pipi is measured with a ruler while a swab is taken, and an agar plate with bacterial growth.

Step 3: Molecular testing

A laboratory test to check for pieces of DNA

This test amplifies the DNA of the bacteria Endozoicomonas from the pipi tissue. Endozoicomonas are a bacteria that have been found in healthy and sick shellfish. The true role of this bacteria in the health of shellfish is currently unknown, so it is valuable to monitor.

A lab PCR machine, and a lab worker transferring samples

Step 4: Histology

Microscopic examination of cells and tissue

Histology is used to detect diseases or pathogens within the pipi tissue and provide a general overview of health. A cross section of animal tissue, with all the major organs, is taken of the pipi, dyed to improve contrast, and then viewed under a microscope.

Collection sites

We collected pipi from four different places. These were:

  • Waipū River
  • Ruakākā River
  • Mair Bank
  • One Tree Point.

Use the map below to learn more about each site and the pipi that live there.

1

Whangārei, New Zealand

2

Waipū River

This population of pipi is found in the estuary part of the river. Other marine organisms have been harvested here in the past, but in recent years due to reduced populations harvesting has been minimal.

3

Ruakākā River

This population of pipi is found in the estuary part of the river, an area which was once dominated by mangroves. The surrounding area is residential. 

4

Mair Bank

Mair Bank pipi are particularly significant to the Patuharakeke hapū. The pipi banks line the mouth of the harbour and can be seen at low tide. The surrounding area is industrial.

5

One Tree Point

This population of pipi line the shallower habitats of Whangārei Harbour. This population reside in sandy/muddy substrate with a high presence of seagrass growth. The surrounding area is residential.

Results & findings

A summary of key collection details, general health observations, and bacteria present in pipi over the course of the study are presented below.

External observations by location

Waipū River

The pipi collected from Waipū had characteristic green and orange flecks on their outer shells. This may be due to particulates in the water from the surrounding area.

It was also common to observe algae and barnacles attached to the upper end of the pipi shell.

A closed pipi sits on a lab bench. The pipi has green algae attached to barnacles growing off its left side. Text on the image says "average pipi size collected ~43mm"

Ruakākā River

Pipi from Ruakākā had discolouration to the shell, commonly black and oranges. Some pipi had algae and barnacles attached to the outer shell.

Pipi from this population were characteristic for having thin and very brittle shells.

Lab image of a pipi. Pipi is asymmetrical, has green, orange and black discolouration, seaweed is attached on the left side. Text on image says "average pipi size collected ~39mm"

Mair Bank

Some discolouration to the shell could be observed from pipi at Mair Bank, commonly black speckling across the shell and sometimes orange tinges in places. Pipi from this population had very thick shells.

Lab image of a pipi. This pipi is paler than the others but features a lot of orange discolouration, seaweed is attached on the left side. Text on image says "average pipi collected ~56mm"

One Tree Point

Pipi from One Tree Point commonly had black discolouration to the outer shells and black discolouring to the tissue near the siphons. Barnacles and small anemones were attached to the upper shell of the animals.  

Results by location

Below is a brief overview of the findings from this study. Included is:

  • Observational research: The conditions during pipi collection including date, moon phase, weather and water conditions. Water temperature is measured in degrees celcius (°C), and salinity in parts per thousand (ppt).
  • Bacteria present: These bacteria play different roles in the health of shellfish - some are normal, some are harmful. Bacteria labelled with a green dot 🟢 are not known to have negative effects on shellfish health, and those with an orange dot 🟠 have a complex relationship with shellfish health and could be potentially harmful.
  • Endozoicomonas bacteria present: Endozoicomonas are bacteria that have been found in both healthy and sick shellfish. The effect this has on the health of shellfish is unknown and is important to monitor. The amount of Endozoicomonas present in pipi collected are indicated as either 🟢 Low intensity, 🟡 Medium intensity or 🟠 High intensity.
  • Histology: The histological observations mentioned below are labelled using dots to describe the potential for causing harm to shellfish. A green dot 🟢 means what is described has no known negative effects on pipi health. A yellow dot 🟡means what is described may have an impact on the health of shellfish.

Click through the slideshows below to see how the results for each location change over time.

Waipū River

Ruakākā River

Mair Bank

One Tree Point

Conclusions

This project has met its aim in creating a baseline health study. This data makes up a historical reference point to the health of pipi in the Whangārei rohe.

Gathering this information is an important step forward. By knowing what the pipi populations look like, their bacteria levels, and expected seasonal changes, this information can be measured against future data recordings to help pinpoint issues.

The project has provided useful insights about the pipi, including:

  • There is no presence of exotic diseases in the pipi.
  • The pipi have distinct characteristics (such as size, shape, and colour) depending on their site and location.
  • We know what type of bacteria are present, and have quantified it.
  • We know how the levels of bacteria change throughout the seasons.

How the bacteria affect the pipi is still unknown. We know some bacteria, such as Vibrio species and Endozoicomonas species, have a complex relationship with the health of marine organisms. There are several current international studies on this topic.

From the results of this study, there is no indication these bacteria are causing harm to pipi. However, it is important to document their presence. Sometimes bacteria (e.g. Vibrio) are not harmful on their own, but the combination of the bacteria plus environmental factors (e.g. temperature) can mean the bacteria do become harmful. It is therefore important to know what bacteria is present, as these could be a potential risk in the future.

These results are a record of the physiological health of pipi from four populations in the Whangārei rohe between 2020 – 2021. This data should be used as a benchmark of health to refer to for future monitoring.

Always report a potential biosecurity threat

This work was made possible due to the care and effort of the Patuharakeke Te Taiao Unit - and because they took action to report the pipi mass mortality that occured in 2019. If you find a pest or disease, or witness a similar event, please: report what you have seen to Biosecurity New Zealand.

Further information

Related news articles

A person bending over in ankle-deep water, with their hand under the water. The image has text overlaid which reads: "In partnership with" and then the logos for the Patuharakeke Te Iwi Trust Board, Biosecurity New Zealand and Ministry for Primary Industries.

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