Marine Life Society of South Australia Inc.
November 2007 No. 349
“understanding, enjoying & caring for our oceans”
This will be the November General Meeting and it will be held as usual at the Conservation Centre, on the 21st November commencing at 7.30pm.
This will be our final meeting at this venue as it has been sold for redevelopment. At the time of writing this Newsletter I have no idea as to where the new Centre will be sited. Watch your emails and future Newsletters.
Our guest speaker for this meeting is Peter Clements from the Natural History Trust who will be speaking on the Trust and Wombats. Should be a very different and interesting evening.
Cleaning Stations and Cleaners (David Muirhead)
More About The Solar-Powered Sea Slug (Steve Reynolds)
As I indicated above this is the end of an era. We have been at the Conservation Centre (CCSA) since our first meeting there in February 1996. Prior to that we met at the Brighton-Glenelg Community Centre at 20 Tarlton Street, Somerton Park and various other locations.
I wish to take this opportunity to thank the CCSA for their hospitality for the past (almost) 11 years and for allowing our mail to be held there.
Now we may have to seek a new venue for the next few months whilst the CCSA sets up in new premises.
Thanks too to all those who have contributed articles to the Newsletter and Journal this year. Special thanks to Steve for his constant supply of excellent articles.
by David Muirhead
We may be looking too hard for similarities between the only known (actually, we can’t even say this for sure, but the Western Cleaner Clingfish probably is a dedicated full-time cleaner) dedicated southern cleaner (ie WCC’s) with a reliance on occupying a prominent cleaning station, and any possible cleaning behaviour by grass clingfish species.
Western Cleaner Clingfish
Photographer - David Muirhead
It seems to me the habitats are so strikingly different that whereas a cleaning station obvious to all confers a wonderful advantage in busy cluttered reefy areas where competition for living space (free-living eg fish, crabs) and food-laden currents (sessile, mainly inverts/algae ) as a priority must equal or exceed in importance competition for niche hiding spots, the converse applies way out in the middle of open sandy or sparsely grassed benthos (to a wee grass clingfish, the bare sand surrounding seagrass clumps must look very scary!)
Here safe havens from pelagic predators, marauding carnivorous territorial fish from nearby reefs eg tubemouths, as well as species favouring grass and sand eg many flatheads, some crabs etc, are clearly at a premium.
Also there is not going to be much topographic variability in relief at all, (apart from the smallish variations between longer-leaved vs shorter-leaved seagrass clump foliage ,which will be very ephemeral such that a good station today may be gone the next day due storms etc) so the idea of a prominent station would seem to be restricted to either:
#1:preferentially perching near the tips of the highest/longest seagrass blades in any grassed area,
#2:preferentially stationing oneself in/on a small but robustly anchored, isolated ‘outlier’ grass clump, or
#3:preferentially selecting one of the above sites that is also favourably located with regard to having adequate water movement to deliver micro-nutrients to accelerate growth of the seagrass itself while also favouring high densities of decapod crustacea such as mysids (an important criteria here seems to be :the more finely shredded decaying marine plant detritus there is lying in shallow depressions on the sandy or silty substrate the better.)
And perhaps one should also include ‘at the optimal depth’-whatever that is-among these last criteria.
If depth is indeed a major criterion for a successful station then obviously tidal variations might themselves mean that cleaner hosts in near-shore sloping sandy/grassy areas would do better to shift from one clump to another further in towards or out from the strand during each tide, but clearly depth must have some role also in determining how good a grassy/sandy site is for use as a station, unlike in reef habitat with it’s (generally, barring eg catastrophic sand drifts capable of burying low-relief reefs , wave action in only the most severe storms) perennially stable relief and landmarks topography would surely far outweigh this criterion.
Another variable that could matter much more in open inshore areas than on reefs is this: In this hypothetical scenario where slow-moving pipefish constitute the main client group, cleaners that learn to follow their clients inshore on the incoming tide and out again on the ebb, provided they can avoid excessive mortality via predation while so doing, would gain the advantage of a more reliable food source, with also a longer time window in each tidal cycle to consume the food (ie parasitic eg decapod crustacean spp living in/on the pipefish, which one assumes would have broad similarities to those found on the non-syngnathid inshore fishes favoured as clients by their reef-dwelling ,very successful and close relatives, the Western Cleaner Clingfish).
Following clients, especially such slow-moving, cryptic ones as these bizarrely camouflaged pipefish, rather than enticing them to visit your station, may indeed be a smart ploy. Alternatively you could describe this as moving your station frequently to provide a better service to slow, very cryptic clients who like you are more vulnerable out in the open and hence unlikely to risk seeking your permanent or semi-permanent station if it means venturing any distance across bare sand from one clump to another, as it usually would at the sites where I’m seeing the most pipefish and which inspired me to put these thoughts to paper.
Photographer - Kevin Smith
It then follows that if the cleaner host has accommodated it’s very specialised clients in this manner, (ie placed it’s services as proximally as possible to those clients without actually becoming a remora!), there is no added advantage to be had from trying to be visible to any pipefish sheltering in other clumps which may often be many metres away across bare sand, as these pipefish will probably stay put, unless desperate for a clean.
I, while scuba diving (either solo, when I always carry my ‘Spare Air’ redundant emergency air supply, wear my ‘Shark Shield’ with fully charged 4-hour rechargeable battery, tow a buoyed ‘diver below’ flag, in daylight, calm seas, minimal current, good viz, depths generally under 3 metres but often around 2 metres or less, shore entry/exit and never at unfamiliar or remote sites, or with the likes of Kevin Smith, Graham Short, Rob Kirk of the UEC and several others including my long-suffering life partner Jenni) have now observed these pipefish in very shallow grassy/sandy areas in calm embayments for many hours (100+) in recent years.
I can confirm that, during daylight hours at least, they are generally very reluctant to move far from their grass clump, even if it is so small as to seem grossly inadequate as protection should a larger predator appear on the scene.
Port Phillip Pipefish
Photographer - David Muirhead
Indeed they seldom move more than a metre away if at all, for any reason short of catastrophic disruption to their hiding place. A good example of this is when, as has happened on odd occasions, a buddy diver has unwittingly so violently flattened the clump of seagrass I was observing with a downward thrust of one of his/her fins while said buddy was lying prone near the bottom with legs stuck out behind observing, like me, another clump nearby !
At dead slack tide, they can be a bit easier to coax away from the clumps, sometimes even appearing inquisitive to the point of voluntarily leaving the clump to follow a very gently drifting diver behind and to one side.
What happens if you approach one of the free-ranging pipefish on those less common occasions where numbers of them are out and about?
Often comprising several species, this behaviour is clearly not species specific within the modest cohort of pipefish species to which I refer.
I recall several dives where quite a few Port Phillip, Briggs Crested, Rhino, and one or two Pugnose Pipefish were widely scattered about in a quite extensive bare sandy area, seemingly almost at random and without individuals seeming to have a particular ‘home seagrass outlier clump’ in mind as a strategic retreat, sometimes not even within a distance of up to 5-7 metres despite this surely being a ‘far horizon’ experience for these slow, very weak swimmers. My guess is that this patch was so particularly well endowed with mysids or whatever their favourite food is that each pipefish felt an individual imperative to capitalise on this feast, but probably they were still only game for this ‘reckless’ behaviour when tide and other variables indicated minimum predation risk!
At all other times, even when one slowly circles closely around the particular outlier grass clump you first find them on, they usually prefer to hide on (those with prehensile tails eg widebody, spotted), in, at the base of, (eg Port Phillip, Pugnose) or behind the seagrass clump. Some species seem to do this almost to a suicidal fault, eg Pugnose and Port Phillip, others with slightly less doggedness but still clearly reluctantly eg Widebody, Rhino and Briggs Crested.
Photographer - David Muirhead
As noted above there are what I as a conservation diver would see as special occasions when one does find most of these species (especially Briggs crested ,rhino and Port Phillip) on or very near the bottom out over bright sandy areas many metres from the nearest seagrass clumps, and also not uncommonly well inshore of the blue line in this same context (even as shallow as 1 metre depth), seemingly more often when there is minimal current and plenty of ambient light ie probably when predation risk is lowest.
But at most other times the rule is: If you want to locate them, just glide from (usually Posidonia spp) outlier clump to clump, stopping to carefully peruse every part of each clump, always paying particular attention to the bases/sheaths of the blades, where they arise from the rhizome. This is the favoured retreat of several species notably Port Phillip pipefish, and here they are often almost impossible to see even at close quarters, with their bodies laying almost flat against the bottom, in parallel with the rhizome (seagrass stolon or runner) or intertwined among the living blades and dense drift detritus including dead leaves/blades which one finds trapped at this same site. The longer, more mature rhizomes, which can be quite tough and fibrous, often also have a depressed groove-like channel in the sandy substrate underlying the linear rhizomes, generated by tidal current or wave action, and this collects yet more drift weed, further aiding the pipefishes' ability to avoid discovery.
...more randoms from Lassiter’s Reef Second Valley, nothing special here but, to everyone with an interest: I always suspect the snook (shortfin pike) one sees idle amongst scaberia may be at cleaning stations, perhaps that of a juvenile Blue Spotted Wrasse, or moonlighter or old wife or even a grass clingfish, which do at times occupy scaberia (and being taller than surrounding plants, would make a good station perhaps)-yes, idle speculation, AGAIN!
While on subject, I also think grass clingfish at Normanville are likely candidates for facultative cleaner role, with a focus on inshore pipefish species as clients, for similar reasons given in my recent email re slender weed whiting S. attenuatus.
Slender Weed whiting
Photographer - David Muirhead
Just finding them often cohabiting in the same small posidonia outliers (almost impossible to find any clingfish or any of the pipefish species below in main seagrass beds nearby) of course proves nothing, but they ARE clingfish, of similar size to the Western Cleaner Clingfish but with longer snouts? Ideal for cleaning pipefish and they (admittedly like many inshore demersal species) favour the same small outlying seagrass clumps where I see the vast majority of Port Philip, Briggs Crested, Pugnose, Widebody, Spotted and Rhino Pipefish in this shallow bay.
Hard to believe that's just coincidence, and surely so many fish in close proximity would be competing needlessly for the mysids/copepods etc in the immediate vicinity (if they indeed have similar diets or at least overlapping dietary preferences which admittedly I don’t know either!!)
Other variables could explain all this eg mysids et al might be found in much higher densities here, sufficient to override the inter-species competition factor, but even looking amongst the seagrass beds on occasions there are still teeming hordes of them yet one still cannot locate any clingfish or pipefish other than along edges (scarce pipefish, NO clingfish) or especially in outlier clumps (plenty of both, at right times of year).
Photographer - David Muirhead
Another possibility could be this: if Tubemouths (S argyrophanes) which are as common here as anywhere (ie if I want to find one, this bay is my best hope, but still much scarcer or difficult to locate dive to dive) do eat grass clingfish and/or slower pipefish species (eg all the above listed species, but not the larger, faster, more wide-ranging Brushtail Pipefish which interestingly are also common here but in my experience almost always over large seagrass beds or with low reef mixed w seagrass-rarely if ever do Brushtails venture out over sand or hang around outlier clumps) then both grass clingfish and slow cryptic pipefish would be easy prey for the ‘stalk and pounce’ behaviour of these very stealthy, brilliantly cryptic tubemouths, but Tubemouths themselves, while bigger than most pipefish and all clingfish, are vulnerable out over sand so tend not to visit these outliers. They however often lurk in the seagrass near edges of large beds, suggesting they may prey upon the smaller demersals that must often have no choice but to run for this cover, eg if stronger wave or tidal action or pelagic predators forced them off their outlier clumps.
I’ve used the Tubemouth (a type of weed whiting) as an ideal example for the purpose above, but clearly other inshore fish groups eg the seemingly ‘garbage-guts’ wrasses and leatherjackets, most of which spend most time in reefy or weedy/grassy areas and much less often venture far out over sandy expanses, would fit the mould too.
Again, that's all for now folks....
by Steve Reynolds
Since completing my March 2007 newsletter article titled “Even More Nudibranch Discoveries” I have found more information about the aeolid nudibranch Pteraeolidia ianthina. This was the solar-powered sea slug found at Port Noarlunga reef by Paul Macdonald on 18th June 2006.
Here (yet again) on page 14 is Paul’s photo of the Pteraeolidia ianthina which featured on page 10 of our 2006 Journal (described as Flabellina species).
Photographer - Paul Macdonald
Bill Rudman of the Sea Slug Forum had commented that the nudibranch’s “white colour suggest it has not yet started to farm zooxanthellae in its body, so I presume it is quite young”. It seems
that solar-powered sea slugs are so-called because they harness solar energy. Bill said that “Pteraeolidia has evolved a method of capturing and farming zooxanthellae (microscopic plants) in its own body. The plants flourish in this protected environment and, as they convert the sun's energy into sugars, they pass a significant proportion on to the nudibranch for its own use.” and “White juveniles are usually found in lush growths of short “turfing” hydroids, but until now no sign of zooxanthellae has been found in the hydroids. Adults can last some time without feeding, presumably obtaining sufficient nourishment from their zooxanthellae gardens. The large solitary hydroid is the preferred adult food.”
Pages 114-5 in Neville Coleman’s book “1001 Nudibranchs” features several photos of Pteraeolidia ianthina. Not one of the specimens look similar in any of these photos.
A photo taken by a James Robins is featured in the December 2004/January 2005 issue of “Sportdiving” magazine (No.107). It is on page 51 as part of Neville’s “Indo-Pacific Identity Crisis” column. James Robins found a 1cm specimen of Pteraeolidia ianthina during a night dive in early June at about 18m in Jervis Bay, NSW. Neville describes it as a juvenile form of Pteraeolidia ianthina, saying that “the very small ones appear to have cerata much closer together and as they grow these are spread out more along the body. Although the adults can be blue, brown, purple or a mixture of several colours when they have various zooxanthellae living in their tissues, the juveniles are always white. However, the oral tentacles always have purple bands.”