Rocks at Bastion Point (pt 2)

We went to Tip Beach so that we could get to the rocks on the western side of Bastion Point.  The tide was forecast to be very low again, albeit an hour later than 2 September.  The pictured geology is usually underwater.

Waves are usually close to the base of these high rocks

The area turned out to be the best reef exploring we have done.  The only contender was Bongoyo Island, near Dar es Salaam but we didn't really know what we were looking at there.  On to the wildlife: I shall attempt to attach names to the specimen later!.

The commonest Sea Anemones Actinia tenebrosa (Waratah Anemone) are usually seen as blobs of purple jelly.  Thus it was excellent to see these three with tentacles waving.

A green Anemone (possibly Aulactinia veratra) in a sandy patch,

From previously identifying these I named them as Sabella sp - a polychaete worm.  That has been upgraded by iNaturalist.org to Sabellastarte australiensis.

Starfish were evident in huge numbers in all types of habitat,

While most were the geometric type there were a few long-armed ones around.  I think this has 11 arms which makes it Coscinasterias muricata.

There were a lot of Tritons on the rocks and on the sand and many shield shells (Scutus antipodes see below - the black object with a small shell in the middle).

This brilliant red shell is a similar overall shape to a triton but lacks the ridges

An Abalone (Haliotis rubra) shell was in the middle of a sandy patch and seemed to be in good order.

On picking it up, it was a rather heavier than usual.  It was still alive!  A few photos were taken as it was carried down to the waters edge.

A second abalone was carrying a lot of passengers.

A fairly typical image of a Shield Shell,  They are also known as Duck-billed Limpet or - according to iNaturalist.org "Elephant Snail"!

When we first saw this we thought it was a Sea Hare (Aplysia sp,).  Later it turned over and revealed itself as another Shield Shell!

There were a lot of fish around in the pools.  Some were pretty small (1 - 2 cm) ..

.. while others were somewhat larger (~15 cm),

Crabs were hiding under rocks

There are various parts of three of the purple jobs in this image.

The sea was moderately flat but the occasional wave broke attractively over the rocks.

I was astonished to find this carved into the rocks several metres from the sand.  I have posted it to the Community Facebook page to try to find some background!

While looking at the seascape photos I noticed these birds flying past - perhaps the Serendipitous Tern is a new species?

As we walked back to the car the setting sun gave a nice effect withe the spray further down the beach.

Getting to car park we were amused by the warning sign.

Obviously "temporarily" means something different to the Shire than to everyone else.  Not only have they not bothered to update it for several days but looking closely at the finishing date (circled) they don't know what year it is!

Rocks at Bastion Point

Frances checked the tide levels and they are as low as implied by the amount of beach visible at Quarry Beach on 1 September.  So we decided to go to Bastion Point on 2 September to explore the rock pools.

The tide was indeed very low.  The first photos are showing the fine stratification visible in the exposed rocks.

A lot of cunjevoi was also exposed.  Interestingly, unlike Congo (near Moruya NSW), this does not appear to be harvested for fishing bait - possibly because it is not usually exposed?

A couple of images of small rock pools.

A starfish in a small pool.  There were many of these around: the largest group I found was about 10 in a pool now more 50cm diameter.  I am unsure of the scientific names (Meridiastra seems to be a likely genus) but this site appears to have a good set of details and suggests that some of them at least were Meridiastra calcar.
.

A brittle star hiding under a ledge.  Also in the Port Phillip website.

A very interesting sea anemeone:  I think it may be Oulactis muscosa.  

After getting kicked off the beach by a very grumpy guy associated with the dredge (which seems to be needed 50% of the time due to poor design of the boat ramp) we looked down on the rocks and saw two of the 'specials' of the local bird life.  An Eastern Reef Egret ...

and one of two Sooty Oystercatchers (the second was catching oysters behind the rocks in the background).

These birds can be surprisingly hard to spot given the lurid colour of the beak.

August weather report

Overall a quite dry month with moderate temperatures.  It seemed to be windy, but my data suggests March was more so!

Rainfall

For the benefit of those who can't remember this phenomenon Wikipedia defines"rain" as 

"Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity."

We did actually get a small amount (32.6 mm) this month.  Much less than both last year and the median fall (61.2 mm).  Surprisingly, of the falls recorded since 1975 this is the only 9^th lowest.

 The shortfall was entirely due to getting relatively little rain when it did fall.  The number of days with more than 0.2 mm was right on average, and last year.

 I have a data series giving the daily cumulative rainfall through a year which I use to calculate a pro-rata estimate of the annual fall.  As at the end of August this is showing a total for 2019 of 578 mm.  If that happens it would be the lowest fall (by ~70 mm !) since the series began in 1975.

Temperatures

The best measure of overall temperatures is the difference between the average temperature for this month and the long term average for the month.  In shorthand, the anomaly.  For August 2019 that was -0.39^oC.  So a little cooler than usual.  (Climate-change denialists shouldn't get excited and cherry-pick that number: it is the first time this year that the monthly average is below the long-term average. Also, over the 25 years of the series the slight trend is for there to be more months per year with above average temperatures than below average.)

This next chart shows how the month-to-date-anomaly changed through the month.  For this longer term series I have used data from the BoM site near the airport.

The table below shows the cross classification of extremes above and below average for the date.

	min above	min below
max above	4	7
max below	12	8

The other general way of looking at the months temperatures is to report the daily extremes, as measured by my weather station at Angophora Dr.

The smallest range of temperatures was 4.8^oC on the 12^th and the largest range 16.5^oC on the 24^th.

Maximum Temperatures

The average maximum for the month was somewhat lower than for 2018 and the longer term average

Minimum temperatures

The average minimum temperature (at our house)was a little above last year and very close to the long term average (both from BoM).

The lowest temperature recorded by BoM was 1.3^oC and at our house 1.9^oC.  It is not unusual to get one reading below 2^oC (ie a light frost) in August with such minima being recorded in 17 of 27 years since 1993.

Humidity

The pattern of daily humidity readings at our houses hows a reasonably moist month especially in the middle of the month when readings were above 60% at 1500 hrs.

During the month the range of humidity through the day is illustrated by the mean rH +/- 1 Standard Deviation.

This shows that the range of rH was quite stable, expected to be between 60% and 90% early in the day dropping to 50% - 70% by mid afternoon.

Looking at my rH values compared to BoM data for earlier years shows this August to have been moister than last year at both standard times, but a little drier for the morning reading.

Wind

Assessing windiness by the amount of vegetation blown down, this was a very windy month!  Charting the daily wind run shows 2 periods of extreme blowiness, and it was the second (from 21^st to 23^rd) which did the bonsai-ing.

Looking at the longer term data I have for wind runs shows an interesting pattern with March 2019 appearing to be even windier.

That is "interesting".  I have looked at the data for March and can see no obvious outlying readings in the data.  Comparing daily windrun with maximum daily gust shows a broadly similar pattern (correlation of 70%).  It's unfortunate that:

• it was the first full month of observations; 
• it was 6 months ago (so I have no great memory of my observations at the time); and 
• BoM doesn't offer daily windrun data for current months.

But I have no objective grounds for amending (or ignoring) the data.  Since I drafted that Frances has commented that when we first moved in (ie including early March) she noticed the wind howling down the flue of our stove.  That hasn't been so evident recently.  This tends to support the data as real, not a figment of of my weather station.

The direction of wind was as normal, mainly from the segments SW -NW.   

The proportion of readings from the dominant section of the compass (~85%) has been higher in more recent months than  in March-April (63%), showing that there have been more fronts coming through from the "West" than low pressure systems perched off the coast.

Where has the sand on Quarry Beach gone?

Following a report  and video of a whale Broaching off Davis Beach yesterday we decided to take a look at Quarry Beach today.  The first sight we had was that the beach was a lot wider than usual!

As a result of the low water levels there was a lot of exposed rock.  There would have been more exposed rock if so much of it was not covered with mussels!

Where there was no mussels there was seaweed.  Sometimes green ..

.. sometimes brown ...

... and sometimes a strange white gelatinous form!

As well as mussels there were limpets and ...

... particularly at the Western end of the beach, chitons.

I have concluded that there was at least 1 vertical metre (and possibly 1.5 m) of rock exposed that is normally underwater.  This meant that some life that normally spends its time underwater would have been exposed, if not hiding in crevices.  Here is a crab!

These annotations may make it easier to spot: the crevice was about 10cm deep so difficult to get the camera in, and the lens blocked my vision!

A sea-anemone was easier to pick out.

As we walked down the beach we kept a sharp eye out for cetaceans but no luck.  That did lead to me seeing a Sea-Eagle well out to sea.  Then noticed a second perched in a dead tree!

It's always a good day when one sees these birds!

The large rocks at the end of the beach were endowed with Great Cormorants.

Kelp was evident in this area.

Due to the low water level it was possible to walk round the end between two outcrops.  This passage is normally at least 1 m (plus wave height) deep, and I would expect quite a strong current.

The action of the waves has sculpted out an attractive groove in the rocks.

As the tide seem to be coming in, and we didn't want to scramble over the rocks or up the cliff, we retreated quite soon.  As we walked back we noticed a couple who had gone round the sea-end of some other rocks getting quite damp as they waded to the beach.