Rock pools at low tide

When there is a very low tide the rocks and pools between the Great Wall of Wasted Money (aka the breakwater) and the tip of Bastion Point are extremely interesting.  There was a very low tide on Monday 30 September and we got to check them out (by walking from the Tip Beach car park).  In most cases where I have attached a scientific name it has come from a Port Philip site.

These first photos are included to show the variety of life in the pools.

A very large Australian RedTriton (Charonia lampas) with the body sticking out!.

Another shell extruding itself.

Winkle tracks!

A sea anemone.

A couple of seastars Meridiastra calcar investigating a triton

The next image shows a medium density of sea stars.

Coscinasterias muricata: this normally has 11 arms but as it multiplies by splitting it is possibly not surprising that one is missing.

A sea urchin

Chitons are normally found welded to rocks.  This large one was laid on the sand and when picked up curled itself up.  One of Frances' books refers to them curling up like an armadillo.  Here is one curled!  As is often the case with invertebrates the defining features seem to need a microscope - if one can understand a statement like "pustules on valves; furry girdle; sutural tufts".

The empty shell of a Shield Shell (or Elephant Snail - Scutus antipodes).  It is forming the base for a lot of 'normal' limpets!

An aggregation of abalone (Haliotis rubra).

An abalone showing its black lip.

A little out of sequence, but we followed up by going on an orchid hunt to Betka and coming down to the Beach found this attractive thatch of sea grass over some vertcially aligned rocks.

In the preamble I mentioned having to walk from Tip Beach car park.  That is because the Bastion Point ramp is (yet again) closed as the Shire attempts to dredge the sand bar from the exit to the ramp.  Some of the issues involved are covered in this article in the Eden Magnet.

My main issues with this are:

1. why do they have to cut pedestrian access along the car park while the dredge is in the area? (that is the biggie for me).
2. why does the exit silt so quickly (this time it was cleared and silted again within 2 weeks)?
3. is the Shire going to sue whoever designed the ramp for bad work?

September 2019 Weather report

Summary

Overall a quite dry, but windy month.  Temperatures were a mixed bag, setting a record for high minimum (on 20th) but the temperature anomaly was minus.

Details

Rainfall

We managed to get 41.2 mm of rain at Angophora Drive.  This compares with  60.4 mm recorded by BoM at the  Airport and  29.6 mm at BoM on. Gabo Island.  That pattern suggests that the rain was quite squally, with falls dependent on just where the cells passed.  While we haven't had any days of really steady rain Angophora did get 18.8 mm on the 9th: this was the first fall of more than 10mm since the 5th of May!

Overall we did better than last year (comparing, a little dodgily, Angophora this year with BoM last year) but were way down on median fall for the month.

Doing a pro-rata estimate of the annual rainfall, gives an estimate of 570 mm for the year.  The previous lowest fall recorded, since records began in 1975, was 657 mm in 1980.  The values given by prorating year to date totals show a fairly stable situation in recent months.

The BoM produces a wide range of rainfall maps both summarising history and looking forward.  The "history" set includes a map showing this area to be amongst the worst in Victoria in terms of rainfall deficiency.

Looking forward doesn't give much cause for optimism either.  We have a 25-30% chance of rainfall greater than median over the rest of the year.

I think Hanrahan is clearing his throat!

Temperatures

The best measure to summarise overall temperatures is the difference between monthly average temperature and the long term average temperature for the month.  For September 2019, using BoM Mallacoota data for both values, that came in at -0.2^oC.  Very close to no difference.  This was a balance between a majority of days (20/30) having an average below the mean for that day and a few days in which the average was up to 6^oC above the mean.

To finish this overview, here are the daily extreme temperatures through the month. Comment on the two series follows below, but the minima on 20 -21st were remarkable!

Maximum temperatures

The average maximum for the month was 18.1^oC, ~0.5^oC above the average. So far this year 8 of the 9 months have had an above-average mean maximum temperature (if that set of comparative adjectives make any sense).  The same applies whether using data from my WS or the BoM series.

The mean maximum temperature was higher than last year and the long term average.

A time series of average September maxima since 1994 looks like a profile of the Great Dividing Range with no obvious trend.  

Minimum temperatures

The average minimum for the month was 8.4^oC: a little above average and last year.  

Referring to the trace of daily minima in the preamble to the temperature section, the precise comparison of my temperatures on a sensible 24 basis against the BoM on a hoss'n'buggy 9am approach is difficult for minima.  However sticking to the BoM data the minimum of 16.9^oC on the 21^st was the warmest September minimum since 1993 by 0.6^oC.  The 15.7^oC recorded on the 20th was the fifth warmest.  (If those two days had recorded the average minimum for the dates the anomaly would have been 0.1^oC higher than observed: surprisingly little impact.)

Again the majority (7/9) of months for the year show an above average minimum temperature with BoM and WS giving similar patterns.  (I have also checked the daily minima for the two sites against each other and the correlation is very solid at 92%.)

The time series of average minimum temperatures for September shows no obvious trend .

Humidity

Humidity is rather difficult to make large statements about as it seems that for some months - particularly September - there are significant differences between the BoM site and my WS.  Until I have more data for my WS, perhaps enabling some calibrations, I will restrict this section to showing the daily lines for 0900 hrs and 1500hrs

It is far from helpful that the only detailed BoM data available is for the very dry 2018, when both humidities were significantly below the long term BoM averages.

Wind

Nearly all of this information comes from my WS as BoM publishes very little information about wind.

Speed

The daily wind run on the 20^th was 519 km.  The longest I have recorded at Angophora Drive.

The month as a whole was the windiest I have recorded since February.  The uptick in average daily run fits with BoM historic data.

Direction

The predominant directions of the wind were South West to West, followed by North West to North.

Compared to overall wind direction for previous months September had many more observations from West and a balancing less from North North West.  However when the directions are ranked in order of prevelance of wind the ranks only shift by +/- 1.

Random Natural History

This post is a selection of photos and witterings about recent sightings in te Mallacoota area.  It begins in Gipsy Point cemetery, which we visited briefly on the way back from Canberra.

When we visited the Cemetery with the Mallacoota and District Historical Society there was some commentary about the "bloody orchids".  This followed a comment about how good it was that much of the site was not mowed during orchid flowering season.  The speaker explained that the late Alan Peisley - a trustee of the Cemetery, who spent a lifetime studying orchids - considered that the orchids needed the open habitat provided by mowing.  (That is supported by the great display currently, near the Gun Club.)  The key point is to avoid doing this in Spring!

On our visit (28/9) there were a good crop of Glossodia major, several Diuris pardina, and quite a few buds of Thelymitra sp.  The big deal was a flower of Caleana minor, the Little Flying Duck Orchid.

An orchid expert friend has pointed out that as the labellum os folded  against the column the flower has probably been pollinated.  The ID was assisted by the red leaf. 

On the 29th we saw an Australian White Ibis taking breakfast.  The eel would probably have preferred it to be raiding garbage bins.

Along the bike path there was an impressive clump of Kennedia prostrata  (aka Running Postman).

For some reason I have always pronounced the genus name as Ken-needier.  A friend prefers  - I now think correctly- Kennedy-ugh.  Whatever, it's pretty in close up.

The Melaleuca armilaris is hitting its straps.

It is a very low tide at present which exposes a lot of interesting marine life in the pools at Bastion Point.  On this large rock I counted 36 Shield limpets (plus 3 Abalone).

An interesting Brittle Star with about 10 arms.

One of a pair of Sooty Oystercatchers.

On the 30th there was a fall of virga, leading to an aerial rainbow over Karbeethong.  No reports of pots of gold have been received thus far.

Its everywhere

When we first moved down to Mallacoota we were almost wondering what had happened to the flowers that we had previously noted.  Just recently it has seemed that everywhere we go there are copious, and interesting blossoms!

The first few images are from a walk through the forest to Pebbly Beach.  Idon't normally photo rushes etc but this looked interesting.  I think it is a species of Lomandra after the floral parts have dropped off.

Many finger orchids (Caladenia sp) in a range of colours all over the forest floor.

Acacia verticillata is still in flower

Coming up from the beach we found a group of Pterostylis nutans nodding away

A single P. pedunculata.

Te most excitement of the day was finding this Green-comb Spider Orchid between the beach and the footbridge.  Its scientific name is Caladenia tentaculata: ie the same genus as the finger orchids!  How that linkage is made is bewildering, suggesting that dosage needs to be adjusted for a few taxonomists!

A close-up of the combs.

Another pretty Pomaderris.

On the way back to Betka we paused briefly to view a sea of Patersonia in the slashed heath around the BoM site and air navigation towers.  The paddock was essentially purple.  However when one of the group went back the next day all the flowers had gone.  That observer marveled at how the plants had coordinated their flowering to one day!  Assuming that the plants are fertilised by insects  - and I can't see why such lurid flowers would be developed for wind pollination - the local insects also got themselves organised rather well!

These are the images from the Gun Club Heath.  which we visited on the 26th.  We saw quite a few 'normal' Diuris orientis.

We also found these strange looking all yellow orchids.  They were definitely not D. chryseopsis (Golden Moth orchid) and turned out to be an unusual yellow form of D. orientis.

The astonishing sight here was a huge number of Glossodia major (Waxlip orchid). 

They were in profusion on both sides of the airport fence, in approximately the area outlined in red (possibly a wider area as we didn't explore everywhere).

Google Earth tells me this is ~11 hectares or 110,000 square metres.  I had guessed at one orchid per square metre giving 110,000 plants which seems unbelievable.  However at a minimum there were many thousands of these orchids present.  This just shows what can happen when vegetation is opened up!

We also found a few spider orchids: again C. tentaculata.

Over by the Gun Club fence we also found some sun orchid buds.  This one was more red than it appears here and was either Thelymitra rubra or T. carnea.  The dry habitat suggests T. rubra but a later visit is needed to confirm this.

We also explored the bush, trying to find a track down to the River.  We failed on that, but did find this very large bracket fungus, knocked off a tree which had become horizontal.