Category: Restoration

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Browns Island Mussel Reefs

Or what is left of them! Even the oysters are swamped by mud from the Tamaki estuary. Wikipedia needs updating:

“The flatter areas to the west have very large part submerged mussel beds which extent out 100 m (328 ft) from the shore preventing easy landing”.

Now the exposed rocks are surrounded by thick mud.

Some green mussels in the large clumps. They were not often dominant.
Some green mussels in the large clumps. They were not often dominant.
Most of the solo green lipped mussels were around 9-10cm.
Most of the solo green lipped mussels were around 9-10cm.
At least 50% of the mussels were blue, of the mussel groups at least 80% of those individuals were blue.
At least 50% of the mussels were blue, of the mussel groups at least 80% of those individuals were blue.
The water was very dirty. It had not rained for at least a day or two.
The water was very dirty. It had not rained for at least a day or two.
This mussel and ambitious eleven armed starfish look like they are suffocating.
This mussel and ambitious eleven armed starfish look like they are suffocating.
Most mussels were above the low tide line. I know this a feature of blue mussels but why were the green mussel following suit? I made the same observation on the Mission Bay reefs.
Most mussels were above the low tide line. I know this a feature of blue mussels but why were the green mussel following suit? I made the same observation on the Mission Bay reefs.
Another example
Another example
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Mission Bay Mussel Reefs

I was very pleased to see so many green lipped mussels here. I thought it might be interesting to survey them as there size and abundance are good indicators for how a restored reef might manage this close to Auckland City.

Mission Bay Mussel Reefs


REEF 1 (huge composite photo)
Reef 1


REEF 2 (huge composite photo)
Reef 2

They look healthy to me.
They look healthy to me.
Northern end of Reef 2
Northern end of Reef 2

I saw the odd blue mussel, cats eye, kina, eleven arm, cushion star, asian tunicate and fanworm but green lipped mussels were by far the dominant species. There were only a few spots where oysters and barnacles were coming out on top.

Some of the seabed around the edges of the reef was littered with shells.
Some of the seabed around the edges of the reef was littered with shells.
But the shells quickly give way to sandy sediment.
But the shells quickly give way to sandy sediment.
This was typical
This was typical
These holes look to me like snapper are active in the area.
These holes look to me like snapper are active in the area.
These white fronted terns looked happy but the black backed seagull and variable oyster catchers were happier eating the mussels.
These white fronted terns looked happy but the black backed seagull and variable oyster catchers were happier eating the mussels.

Size
Most mussels were 7-8cm long. But there were a few around the 10cm mark. I think I was looking at two generations?

UPDATE: November 2016
The green lipped mussels have been heavily harvested. There are maybe 20-30 adults left across both reefs. Some juveniles amongst the remaining blue mussels. Rock oysters and blue mussels now the dominant species.

I was pleased to find the occasional juvenile green lipped mussel amongst the blue mussels.
I was pleased to find the occasional juvenile green lipped mussel amongst the blue mussels.
Rock oysters very dense in some places
Rock oysters very dense in some places
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Times

Oil While I was cleaning up this rusted oil barrel that had been dumped near a stream in Selwyn Bush decades ago, I thought about how “times have changed”. I guess all I need to do is make them change faster.

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A Dotterel Breeding habitat at Tahuna Torea

After the last count of 50 Pukeko at Point England I am considering trying to find a better breeding habitat on the Tamaki Estuary for the local Dotterel. Michael Taylor can’t recall Dotterel showing any interest in the tidal mudflats in the lagoon area at Tahuna Torea. I am wondering why, as this seems the perfect spot.

Here is a map showing the current state of the islands which are potential roosting/ nesting spots.
Here is a map showing the current state of the islands which are potential roosting/ nesting spots.

Mangroves and other vegetation would need to be cleared to give the birds a 270° view. Gwenda Pulham made the observation that there are no sand hoppers to feed chicks and I should read HANZAB. Which states “Usually feed on firm exposed mudflats, sand or stones; avoid soft sticky mud, e.g. near mangroves.”

But I have seen birds with sticky mud on their beaks. (Ambury park)
But I have seen birds with sticky mud on their beaks. (Ambury park)

So how sticky is too sticky?

This is what most of the mud looks like. Note crab holes and my average footstep depth of 2cm.
This is what most of the mud looks like. Note all the mud snails and my average footstep depth of 2cm.
The mud around the islands is higher and only covered 30 min either side of high tide. Note the extra crab holes.
The mud around the islands is higher and only covered 30 min either side of high tide. Note the extra crab holes.

The odd Pukeko and roosting Caspian Tern is seen on the flats, and occasionally a Banded Rail. But mostly it’s White Faced Herons and Pied Stilts.

If it has a 30% chance or working then I am keen to:

  • Clear dense vegetation from the islands.
  • Remove or trim a large amount of the mangroves.
  • Import shell.
  • Reinforce the islands.
  • Experiment with decoys.

UPDATE: May 2014: Experts think this is a long shot and that I have a better chance of dealing with the Pooks at Point England by poisoning them. But an even better idea is Chick Shelters!

UPDATE: March 2024: Well that worked after all!

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Pest Monitoring

Monitoring Tunnel (S6) Selwyn Bush 24 March 2114

Monitoring cards Selwyn Bush March 2014
Monitoring cards Selwyn Bush March 2014

Selwyn Map

MY IDs: Using this guide
S1 –
S2 Rat
S3 Rat & Hedgehog
S4 Hedgehog
S5 Mouse
S6 Mouse & Rat (confirmed by Camera Trap)
S7 –
S8 Rat
S9 Rat
S10 –

This gives us a an Autumn result for 2014 of 56% Rat, 22% Mice, and 22% Hedgehog.

Wax Tags
Wax Tags Small
These are only ones with marks, note S10 had no wax tag. I assume because of the ink markings and camera data they were both mouthed by rats. I am surprised there is any wax left on S6 given the amount of times the rats ran unto/past the tag (camera observations). On further inspection I think S6 is the only conclusive rat bite. Next time we should leave these out for 7 nights.

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Philosophy

I found this old thing on my hard-drive. Might help me get focused.Why I should dedicate some serious time to Biodiversity
I think the obvious answer is a wetland because those environments were hardest hit buy farmers. Tho interestingly I do not know much about threatened wetland species. Our rivers and shorelines face a lot of commercial & recreational pressure. A wetland also sits at an interesting intersection:

  • When I visit forests I hear a lack of quality in the silence (lack of bird life)
  • When I drive through the countryside I see a lack of quality in the monotonous monocultures.
  • When I kayak in NZ, the water feels empty. I think for me — quality is biodiversity and the water is overfished and often polluted.

It would be magic if I could fill all three buckets with one hose.