Marine Life Society of
South Australia Inc.
Newsletter
April 2007 No. 342
“understanding,
enjoying & caring for our oceans”
Next Meeting
This will be the April Meeting and it will be
held as usual at the Conservation Centre on the 18th April commencing at 8.00pm. Please note we have reverted to our original
meeting time. Our guest speaker is Helena Wescombe-Down who will be telling us about diving at Exmouth.
CONTENTS
Mucking
About At Muston Jetty (Part 2) (David Muirhead)
British
Marine Life Study Society news
MEMBERSHIPS ARE NOW DUE
On behalf of the Treasurer I would like to remind
everyone that memberships are now due. I would help if you could pay without
the need for and embarrassment of further reminders. A subscription form is on
page 15 of this newsletter.
2007 AGM
Committee Nominations
In order to publish the committee nominations in
the May newsletter as required by our Constitution I will need them by 13th April at the latest. As usual present Committee Members only need to
nominate themselves. Others will need a seconder.
Nominations for non-executive positions will be
taken on the night.
The AGM will be held at the Star of the Sea
Marine Discovery Centre at Henley Beach on May16th. Full details as
to how to get there and the programme for the evening will be in the May
newsletter.
Mucking About At Muston
Jetty (Part 2)
by David Muirhead
All pictures are
by David Muirhead and
were taken at Muston Jetty.
The southern
pygmy squid Idiosepius notoides
is said by Mark Norman and Amanda Reid as the authors of “A Guide To Squid Cuttlefish And Octopuses Of
Australasia” to be found in seagrass beds particularly eel grass
(Heterozostera and Zostera) right along Australia's South Coast.
Southern Pygmy
Squid
I don’t know
about you but when, as happens all too often in my experience, I read such
statements before actually seeing said creature in the wild, I become an
instant skeptic.
How could
I, having combed our shallow areas with snorkel and scuba searching
for any and all mobile critters be they large or small for
so many years, not have seen even a single one of these little
squid?
Are such
authors trying to tell me that I’m blind or stupid?
Well, Idiosepius
the genus may be, but who was the idiot who forgot to pack his wetsuit hood?!
I'm a ‘cool
season convert’ to dry suits and am of course aware that if one doesn’t
wear a hood then bulk kilojoules are very quickly lost via our very
vascular necks and scalps.
In southern Oz
dry suit divers mostly don't bother with the extra cost and hassle of dry
hoods.
A wet hood is a practical and affordable way to have the best of both worlds-provided one’s pampered, tiny brain can
fulfill its pre-dive planning role from one winter to the next.
Mine
couldn’t!
Southern Dumpling
Squid
Nudibranch
So here was I,
midwinter, on the frigid shores of American River, getting into my old 7 mm
two-piece wetsuit with hood incorporated, in lieu of the much preferred dry
suit, because it is better to be a bit cold all over including one’s
head than to have a comparatively
warm torso contrasting with an absolutely frozen face and
skull.
(And these days I’m also reluctant to dive without some head protection from
minor abrasions, bites and stings even in warm water so any hood is
definitely better than no hood).
On this
scrubby strand there was no wind at all and it was the middle of the
day as well as being the middle of winter but even the birdsong from
the grey fantails and grey currawongs sounded uncharacteristically
subdued, matching both my mood and the heavy overcast sky.
Cowry
Crinoid
But, albeit
faintly, I could still hear some glossy black cockatoos in the sugar
gums and sheoaks away to the north just above the township of American
River, and I'd like to pretend now that this was a good omen for my
pending encounter with what until then was for me a species I’d
never seen nor heard of.
I could
imagine that they were talking each other's courage up for their or future
generations eventual inaugural and long flights across to the
mainland from Penneshaw to Cape Jervis, in which they would be trying
to emulate the flights of their more numerous ancestors in the years when
they were still commonly sighted feeding in the
sheoak woodlands on the southern Fleurieu Peninsula.
These
thoughts reminded me of one of my reasons for diving here: the lure of
perhaps photographing some rare or endangered species of marine life-for no one
can deny that Pelican Lagoon and the American River Channel are
biodiversity hotspots-and this Muston jetty shore dive is located at one of the
narrowest and deepest parts of the channel.
Rather fancifully one could liken it to a very miniature version of
Backstairs Passage if only in that a large volume of clean nutrient
laden seawater has to pass up and down this channel several times daily with
the tides and so although much shallower and siltier than its
Backstairs Passage counterpart it represents a paradise for
filter feeders including sponges ascidians bryozoans scallops and
fanworms, and this busy substrate in turn provides shelter for a vast array of
mostly smaller invertebrates such as the pygmy squid which is the subject of
this article.
There is
also a fairly good variety of red algae along with the usual smattering of
browns and greens, but overall the substrate is dominated by invertebrate life
with marine plants taking second place at least in the channel.
Indeed
quite large areas of the steeply sloping sides of the channel at Muston Jetty
between about 1 m and 8 metres depth superficially at least resemble the
typical mix of invertebrate life combined with algae that one tends to
get on many South Australian jetty pylons, but this occurs without the artifice
of pylons themselves as there is essentially no remaining jetty below high tide
mark.
With a
renewed resolve I completed my preparations.
Although
using my mobile phone seemed a travesty in such a peaceful locale I
dutifully told the punters sitting around the open-hearth fire back at the
American River shack of my whereabouts and intentions.
Then, in
true Celtic tradition I tried to do what all divers eventually must
do: enter the water!
Holothurian
Isopod
After an
exhaustingly slow tramp in full clobber across, or more accurately through, the
treacherously boggy shoreline with its minefield of slippery green rocks
sown by a vengeful Mother Nature, I gratefully contrived to lower my scrawny
frame into the absolutely freezing briny.
Shrimp
After fully
inflating my buoyancy compensation device I hoped that I might by some
metaphysical fluke actually float here in only 25 cm of seawater, because I was
desperately keen not to take even one more step through that quagmire of
slippery rocks and sucking glug.
But float
I did not!
So
near to FDW (floatable depth water, surely only a few metres further out)
yet so far.
When one
is face down (with snorkel in mouth and regulator at the ready in right hand,
don't you worry folks) in the water at this depth, well, there really is no
turning back.
At such
times even real men have no choice but to.....well, half crawl, half pull
themselves, and half swim (yes that's one and one half times one organism’s
total aerobic activity, but believe me, I wasn't counting at the time!) towards
deeper water.
After so
doing, the moment I hit the grand depth of 60 cm I was rewarded by the
prompt and unabashed inquiries of two pygmies.
Mind
you, with such a clumsy entry it was quite a few seconds longer before the
silt cleared enough that I could be sure I really was looking at the two
tiniest cephalopods I’d ever seen, and I was lucky that there was already
a bit of an incoming tide helping to clear my self generated silt away.
At the
same time my already tired but eager eyes were still adjusting to the
even lower ambient subsurface lighting of the gloomy winter’s day.
Snapping Shrimp
I’ve pretty much
described the little critters’ endearing appearances and behaviours in
part one of this article so I won’t repeat myself. (See October 2006, Number
337.)
Snapping Shrimp
Using my trusty
old Nikon F2/55mm macro set up housed by Ikelite and matched with a
single Ikelite Substrobe 200 I proceeded photograph these tiny squid.
They are
so small that I would have done better with my 105 mm lens, nevertheless
in some of the photos at least one can clearly identify the animal.
Anyway
I’ve done a little bit better on a few dives at other inshore South Australian
locations such as Tumby Bay jetty since then.
As is
usually the case once one gets one’s eye in I have increasingly
noticed these little squid, which I can now quite often find in suitable
shallow seagrass sites (indeed they usually find you if you just sit still for
a few minutes after entering the water as they are very inquisitive, like
all cephalopods) and which of course have undoubtedly been there in numbers at
these dive sites all along!
And
although I forgot to mention the presence of scanty seagrass patches of mainly
Zostera or Heterozostera eel grass at this Muston jetty site particularly
in the shallow more gently sloping areas, I have no reason to doubt the authors
in this detail either.
So
needless to say the above book authors have again been proven correct and
my initial scepticism as usual has been proven unfounded.
Having
said this the adults at least do seem to be better adapted to cryptic
existence on the much broader Posidonia seagrass blades, including
their ability to square themselves off to look like the
short dead drift fragments as I described in part one, and although
there was minimal Posidonia actually growing at the Muston jetty site amongst
the scanty and much smaller eel grass, here as at nearly all inshore
sites in southern Australia there are always plenty of the dead
Posidonia fragments (and of course also often mixed with the even
shorter, but still with 'square- type' profiles at the ends, Amphibolis
leaf segments) amongst the detritus both on silty and sandy bottoms and in
nooks and crannies among sponges and other fixed benthic lifeforms.
Another
reliable site for these miniature squid, Tumby Bay jetty, while certainly
having eel grass ( which is often along the edges of Posidonia or more
scantily as understory to the very robust Posidonia at this site) is
dominated by the larger seagrasses particularly Posidonia, so I rather think
that this squid when adult would be likely to favour the edges of Posidonia
beds whilst juveniles and immature individuals might be expected to preferentially
inhabit the more diminutive eelgrass beds or a mix of both.
However
this is once again largely speculative on my part and based on my as yet
very minimal observations I’m not really in a position to speculate- but
I can’t help myself!
As a master
of stating the obvious I will now close by saying that I survived this dive
despite the cold and despite my ignominious and labourious entry.
Sponges
And as always I
enjoyed that post dive exhilaration, not to mention the chance to blabber on
about what I’ve seen to all and sundry back at the shack.
That
night was one of the best sleeps I’ve ever had-just like the one you are all
currently drifting into having got this far with reading this riveting
article!
British Marine Life Study
Society
MARINE
LIFE NEWS
Email:
glaucus@hotmail.com
(For full contact
details please use our Links page on the MLSSA website.)
Reports of marine wildlife from all around
the British Isles, with pollution incidents and conservation initiatives as
they affect the flora and fauna of the NE Atlantic Ocean.
29 October 2006
Pipefish
are now swarming the sea around Shetland. I have seen them while off fishing,
lying dead at the side of the marina (dragged up by an otter) and dropped
around by seabirds. The Skeld Marina on the west side of Shetland is alive with
pipefish - enough to keep 2 resident Guillemots fed apparently. The oil and
general mess of the marina waters does not appear to be putting off these fish
or the many birds, seals and otters that appear to be feeding on them, within
and outwith the marina.
Until a couple of years ago pipefish were a virtual
unknown around here - nobody had heard of them even. Now they appear to have
supplanted sand eels as the main small feed fish for other creatures. I say
this because sand eel populations are reported to have crashed, while there is
no doubt the pipefish are now a very common fish here - and this has happened
in the span of a couple of years.
I have also heard fishermen say that the sea around
Orkney is thick with pipefish and that is a new phenomenon for them too. Other
warm water species are also increasingly prevalent - even tuna seen between
Orkney and Shetland.
From my own
angling observations, haddock, which was plentiful in 2004/2005
was almost entirely absent on the patches I have fished on this year (all within
a mile of the shore). There was some cod around including quite decent sized
fish. Ling has been plentiful and there has been so much mackerel in the sea
all summer that sometimes it has been difficult to hit the seabed with your
gear. That has been the case with the big commercial mackerel boats
also - some have taken their remaining end of the year quota in 2 weeks (ie
several thousand tonnes of big-sized fish)!
Is the appearance of “exotic” species down to
global warming? I cannot think of anything else that could have such a rapid
and radical effect. This summer had been exceptional in Shetland. We just had
our first (very savage it has to be said) winter gale on 25/26 October.
Normally, severe gales start around mid-end September. We've had at least a
month extra on the norm for the growing season and the summer has been
generally warm if not exceptional for temperature. We'll maybe see if it
develops into a trend?
I don’t know what species these pipefish are,
having not studied them in detail. I would say they are a pinkish, orange
colour, but I’ll use your notes for identification.
Report by
Peter Johnson
11 February 2007
I found this Snake
Pipefish, Entelurus aequoreus,
(photograph above) washed up alive on the beach at Saltburn, Cleveland. It was
40 cm long. There were hundreds of them along the shoreline, most were alive
and we put quite a few of them back into the sea. The sea was quite rough that
day.
Report by Marion
Moore