The Peel-Harvey Estuary
Tidal MovementI was unable to find any very useful reference on the Internet about the amount of tidal movement that was typical in the Peel estuary so I decided to take my own measurements at a time of Spring Tides, the new Moon of 2022/04/30.
Six readings taken over a period of 22 hours at a period of Spring tides (new Moon, 2022/04/30-05/01) indicated a total range of about 20cm. This seems to be about a third of the tides on the coast.
(Tide levels are available on the Internet for 'Mandurah' but where these levels apply to is not given. If they are in the estuary then they are probably substantially less than on the coast.)
Water colour change
On this day we noticed it was clear but strongly coloured brown, probably from tannins that had washed in with the high flows in the Murray and Serpentine Rivers that feed into the estuary.
The data I had from Dr Steve Fisher, Operations Manager, Science and Waterways, Peel-Harvey Catchment Council, showed some very low salinity readings had been collected in the past, so it was quite possible that this water was almost fresh.
Photo iPhone 11 Pro, wide angle lens, 1.54mm, 2022/08/11
The water in the harbour was not so strongly coloured as the water that I recorded above, on the previous day. I tasted the water on both sides of this photo. Both were somewhat saline, I couldn't be sure if there was any difference in the salinity between them.
Photo iPhone 11 Pro, 2022/08/12
Dead trees in the Peel lagoons
A very few of the thousands of dead trees in the Len Howard Conservation Park (there can be little doubt that the deaths are due to climate change). I think that these particular ones are in what I have called the Spoonbill Rookery near Mandurah Quay.
The most obvious possible cause for this would be an increase in the salinity where the trees are. It is not easy to find out if this is definitely the cause.
Salinity recordOn 2022/04/13 Dr Steve Fisher, Operations Manager, Science and Waterways, Peel-Harvey Catchment Council - Provided me with data from “the Marine and Freshwater Research Laboratories (MAFRL) from five sites in the estuary between the 1970s and mid 2001.
From these data I found that the average of all the top salinity recordings at site #2 (near Dawesville and Falcon) from 1977 to 1994/04 (when the Dawesville Channel was constructed) was 25 parts per thousand (ppt), bottom salinity 27. After that time, up to mid 2001 when the data series ended, the averages were 32 and 35 respectively. From that, for what it is worth, the top salinity (having the greatest relevance for the trees) has increased by 28% since the construction of the Dawesville cut.
From the above it does seem that the average salinity in the estuarine system has increased. My impression, again, for what it is worth, is that the increased salinity is likely more to do with deceased rainfalls since the 1970s (itself due to climate change) than due to the construction of the Dawesville Channel.
“A 20% drop in rainfall may not sound very dramatic until you understand the impact it has on streamflow – the water that runs off into our dams and other storages. The decline in rainfall throughout Perth and the South West has seen streamflow reduce by an average of over 80%!”
It seems that rainfall and runoff is likely to continue to decline into the future. Quoting Climate projections for Western Australia; Rainfall projections published by WA department for Primary Industries and Regional Development:
“The drying trend in the south-west will continue as greenhouse gas concentrations increase according to the modelling. The projected changes differ a little from the observed changes in recent years. There may be an increase in synoptic systems bringing helpful rainfall to the northern and eastern grainbelt and south coast, but the projected drop in the number of deep low-pressure systems means much less rainfall for the west-coastal regions and far south-west. The overall increase in atmospheric pressure over southern WA will likely drive a shift to a more settled weather regime, with more highs persisting for longer.”The reference was marked "Page last updated: Thursday, 15 April 2021."
Len Howard Conservation Park
Weeds in and near the LHCP
The patch of fleabane in the image on the right was in the southern part of the big seasonal paperbark reserve. Note that it is on a slight mound; I suspect that the surrounding area is seasonally flooded and that this kills any fleabane seeds in the soil.
I sprayed this patch on 2023/01/05
Photo iPhone 11 pro, 4.25mm focal length standard lens, 2023/01/05
Lightning blasted and charred tree
Perhaps surprisingly this was not the tallest tree in the area, but it wasn't far off. I wonder why it was hit rather than another tree? Perhaps it was a better electrical conductor?
The splitting of the bigger trunks and the charring of the top part of the tree are shown in more detail in the following photos.
These photos were taken using a Cannon Ixus 190 on 2022/08/11 a few days after the lightning strike.
Most of the tree was killed by the lightning strike, but a small section was still alive at the end of 2022. It had entirely died by early February.
Note that the largest trunks, on the right and left, have been split. I believe this is caused by the moisture in the tree flashing to steam due to the heating effect of the high electric current.
The big seasonal paperbark swamp (BSPS) in the Len Howard Conservation Park
In 2022 Erskine had a wet winter, by my records there had been 129mm of rain in May, 148mm in each of June and July and about 70mm in the first third of August. Consequently by this time the swamp was full and overflowing into the main estuary pool. I've written elsewhere on these pages, with photos, on the swamp through the seasons.
Photo iPhone 11 Pro, focal length 6mm (telephoto), 2022/07/24.
When is the big seasonal paperbark swamp (BSPS) empty, full, overflowing?I don't seem to have recorded when the swamp started overflowing, it was probably at least a couple of weeks before I took this photo. Surface flow from the swamp into the estuary stopped on 2022/09/28.)
It was sitting quietly beside a path and a man was already sitting on the path when I arrived. I wonder if he had attracted the bandicoot by feeding it?
I have since seen a couple more bandicoots in the Novara Beach Reserve. They seem most likely to be seen at dusk, dawn or night time. Generally, but not always, they are inclined to run into cover quickly after seeing a human.
Kangaroos at a feeding station that someone maintains adjacent to the Len Howard CP
Photo taken 2022/03/16, Canon Ixus 190
In the period at least from February 2022 to the end of 2022 there was a mob of 25 or more kangaroos resident in the BSPS. If anything these kangaroos are even more relaxed around people than those that use the feeding station mentioned above. The most relaxed one of them all is possibly the injured kangaroo mentioned elsewhere on this page.
Added commentEarly this morning (2022/05/05), when there was hardly any daylight, I was walking through the little reserve at the western intersection of Silverton Crescent and Wattleglen Avenue on my way to do a fortnightly plasma donation when I saw a kangaroo in front of me. It casually did a couple of hops in the direction I was walking a couple of times then stopped, stood up to its full height - to intimidate me - and stood as I walked past about three metres away. At its full height it was only a little shorter than me (I am about 1.8m tall).
Injured kangaroo - two photos on the rightThis kangaroo had a badly injured mouth, but was grazing peacefully when I photographed it. It is one of the big seasonal paperbark swamp (BSPS) mob.
I did not see this kangaroo again in the next two months, at least I did not see a kangaroo that I recognised as this one.
I happened across the same kangaroo again on 2022/08/13. This is the best photo I could get at the time.
It looks like the injury has healed quite a bit, but the kangaroo's mouth is never likely to return to anything like its original form.
Click for a more detailed image of the mouth area. Use back-arrow to return.
Photo iPhone 11 Pro, telephoto lens, focal length 6mm.
UpdatesI came across this kangaroo again on 15th August and 25th September 2022, 2nd of January and 2nd of February 2023. In January she was obviously carrying a large joey in her pouch, so she has done very well; in February the joey was following her around. The injury was still conspicuous, but not so much so as it was in the earlier sightings. Oddly she seems tamer than most of the swamp mob, I wonder why. On the February siting there was a young joey near her.
I happened to see her again on 2023/05/12. I could not get a good photo, but I think her mouth looked much the same as it did in 2022/08/13. She did not have a joey following her.
Also see bird wildlife in my backyard on another page on this site.
This was the first lizard that I can recall seeing in the three months that I have so far been in WA. I have not seen any snakes at all. It was between Dampier Avenue and the scrub adjacent to the lagoon.
Update 2023/02/08I have now seen three snakes, probably dugites (Pseudonaja affinis, also called the spotted brown snake) and there are many small skinks about, between about 4cm and 10cm, although they will not usually be noticed until they move for some reason. And I've seen at least one dragon lizard, perhaps a bearded dragon.
I did wonder if the frequent aerial treatment, by helicopters, to reduce mosquito numbers had wiped out the local microbat population. But I read information sheets from the City of Mandurah stating that the mosquitoes numbers are controlled with very specific larvicides (S-methoprene) and Bacillus thuringiensis israelensis.
So it seems unlikely that the mosquito treatments would account the the apparent low bat numbers. I've been told that some bat roosting boxes have been placed, so perhaps the low numbers are related to a lack of roosting sites - perhaps that may be connected to the great numbers of dead trees?
There is also a tap at the car park near "Nature's Eye".
RubbishJust as around where I used to live in South Australia there is rubbish scattered carelessly around the Mandurah area. I intend to continue cleaning up this rubbish in my new neighbourhood.
Today I picked up a bag full in the little reserve area at the western junction of Silverton Crescent and Wattleglen Avenue.
It is common for people to dump garden waste in the local parks.
As discussed on another page on this site, there needs to be a noun for the type of careless, irresponsible, lazy people who do this sort of thing.
Some hundred or so of the plants I put into Crystal Brook Central Park back in SA were pulled up be one or more vandals. Fortunately, to the time of writing, few of the plants that I've put into a small park near my new home have been damaged by vandals.
Dumping rubbish, discussed above, is a form of vandalism.
Valdalism at the train station car parkI noticed on 2022/07/03 that about a half dozen large recently planted trees adjacent to the new multi-story car park had been broken off. There was only one or two that had been left undamaged. By the 5th they had all been removed.
Vandalism of my tree guards2022/07/07; see the page on my projects in the Erskine area.
WeedsAs is the case with most of the public places with which I am familiar there are weeds in Mandurah, adjacent public paths and in parks and gardens. I find the unwillingness of the great majority of the local people to take part in the improvement of their public places puzzling.
Self or community?I suspect that selfishness is a factor in people's unwillingness to look after public parks and gardens, as it probably is in the unwillingness of many to donate blood (only some 3% of Australians donate blood or blood products). On the subject of selfishness, there are many private jetties in the Mandurah area, most have signs on them telling other people to keep off. Surely reasonable use by the public would be unlikely to harm the jetties or inconvenience the owners?
I have made a project of working at improving the parks and paths in my local area. It seems to me only natural that I should want to do this. Yet I get the impression that many people find it hard to understand my actions or motivations. I, in turn, find it very hard to understand their lack of understanding; do they not think that we should care for our public places? Or do they just think, "It's not my job. Let somebody else do it."
2022/07/24, another man stopped and said: "I've got to ask, why are you doing that?" I said something like "I'm digging out weeds; they have no place in a public park." Several other possible answers came to mind after I had thought about it for a while:
Had solar panel shades been installed rather than simple shade sails most of the power consumption of the shopping centre could have been offset and a huge amount of greenhouse emissions avoided (most of Western Australia's power is generated by coal-fired power stations). I estimated that the area covered by the shade sails was 1,320m2, twice that of the Woolworths, Clare, shades, so had solar PV panels been used rather than shade sails the installed capacity would be around 280kW. Such a solar PV installation would generate about 490 megawatt-hours of electricity each year and that could reduce WA's greenhouse CO2 emissions by something like 400 tonnes each year.
I've written a page on solar PV shade in car parks and other places elsewhere on this site.
In 2022 solar PV panels typically pay for themselves in about five years. In this case where the cost of installing the shade cloth sails would have been avoided, the payback time would be shorter. PV panels also have the advantage of casting denser shade than shade cloth, so the cars beneath the panels would be cooler in summer.
One can hint and push but it is a rare thing to get a definite result such as this one. Having the car park lights on only when needed (if that is what happens in future) will reduce greenhouse gas emissions by something like 30 tonnes each year.
In my home state, SA, there are big solar shaded carpark installations at Vicinity Centres (claimed to be the biggest in Australia at the time of construction, 1,400 panels on the car park alone) and Castle Plaza (430 solar shaded parking spaces).
Also see my page on solar car park shades.
Why were we all so unwilling to do something about it? I suspect it didn’t occur to most of us that we could do something about it.
Why did the council allow the fence to encroach on the path when there was no need for it? Why did I put up with it for so long before I did something about it?
I've written more on this subject on another page on this site.
On this site...Bowman Park, Crystal Brook, South Australia
Cleaning up roadside rubbish
Climate change, the world's great threat and challenge
Contributing to our communities
Crystal Brook's Central Park, SA
Destruction of roadside vegetation by a body that should be protecting it
Gleeson wetlands, Clare, South Australia
Why I support the local wind farm
Specific to WAA photographic record of a visit to the South of WA
Fleabane, my efforts to remove it in and near the Len Howard Reserve, and similar local environmental improvement projects
Images of WA, from a new resident
Mandurah volunteer workers; keeping in touch
Mandurah, a note on conspicuous consumption
Names and abbreviations I've used
On this page...Abbreviations and names I've used
Big Seasonal Paperbark Swamp, in the Len Howard Conservation Park
Dead trees in the Peel lagoons
Water colour change
Len Howard Conservation Park
Lightning charred tree in Len Howard CP
Letter to the editor and a result
Names and abbreviations I've used
Primewest, Erskine shopping centre, a lost opportunity
Swamp, seasonal, in the Len Howard Conservation Park
Self or community?
Swamp, how it came to be a reserve
Water colour change
Weeds in and near the LHCP
Weeds; Odd comments
Why walk past, why not fix it?
Why would anyone want to remove weeds from parks?