Missing reef balls

24 Reef balls were deployed in two reefs at Long Bay-Okura Marine Reserve in 2001.

Launching the reef balls, photo care of Jonathan Jaffrey

They were quickly colonised and dramatically increased the biodiversity in the area.

A lonely reef ball, photo care of Jonathan Jaffrey.

I have wanted to find these artificial reefs for years and made three attempts. The first dive from the shore was unsuccessful (its too far out and I dont have underwater GPS). The second and third efforts below used line and sonar but still came up empty. I think they have been buried (sunk into the substrate) but I would love to be wrong. The photo above shows a lot more shell on the seafloor than I found 20 years later. I’m not planning any future searches.

12 January 2022
4:15pm High Tide
5-10 knots
.5m-1m swell
Shaun Lee & Jordi Tablada

Boat to from Winstons Cove to Long Bay
12:00pm Look for Reef Balls:

Zig Zag Reef
36° 40’ 52” S, 174° 45’ 14.8” E
36.681111, 174.754111
5.5m at Low tide

Octagon Reef
36° 40’ 51.1” S, 174° 45’ 19.6” E
36.680861, 174.755444
6.2 M at low tide

Dropped anchor 5m from Zig Zag using Garmin GPS
Dived down anchor with line on reel
Vis 5m surface, <1m bottom 5.5m deep, tied line around anchor, spiral search pattern Let line out >30m possibly didn’t turn enough and made more of a sweeping arc
Hoped line would have snagged of epibenthic fauna attached to reef balls but following line back found nothing
Quick check near boat found nothing c30mins total bottom time
Noted layer of mud under sand
A few cushion stars, some heart urchins, Jordi saw a Spengler’s Trumpet
Some dead tutua shells under sand
Large snapper under us when we surfaced

Dropped anchor 5m from Octagon using Garmin GPS
7 minute look in the direction of the reef
Nothing in particular

2:30pm head back as wind pickup up (15knots developing in afternoon).

Resolved to search with a boat that has sonar / fish finder next time.

Thursday 9 September 2022
High Tide 5:30pm
With skipper Ed Chignell

Zig Zag Reef 6.7m
c7 spirals out from waypoint. No clear benthic structure seen on downscan or sidescan.

Octagon Reef 8m
c3 spirals out from waypoint. Drifted south over fishy looking shape 5m south of the waypoint on the downscan. It was still there 5 minutes later so we dropped anchor on it.

I descended the anchor line. Vis 3m, bottom 8.8m. I spiralled out from the anchor for 5 minutes then headed north for an additional 5 minutes. The seafloor was sand/mud with some shell. Nine cushion stars and about six large hermit crabs were seen in 10 minutes. After ascending and heading a bit further south I dropped down for another 5 minutes to check out another fishy shape but didn’t see any reef balls or fish. Many fish were seen in the fish finder.

Note visibility much better than last dive even tho it rained heavily just a few days ago. Hardly any swell or wind over the last two days.



Article about the find here https://gulfjournal.org.nz/2023/02/reef-balls-rediscovered/

Thanks to Andreas Proesl who has been in touch and supplied his internship report which shows how the ReefBalls were constructed and deployed