From Annemarie.Schmid@SBG.AC.ATWed Aug 14 13:13:03 1996 Date: Wed, 17 Jul 1996 09:08:52 +0200 From: Annemarie Schmid To: Multiple recipients of list DIATOM-L Subject: aerophyllic taxa??? Dear Dr. Reavie, there is another member of the Nitzschia family that can be completely aerophilic: Hantzschia amphioxys ! A former student of mine had collected it when it was growing as a monospecific population on top of an aerophilic lichen that covered a rock exposed to direct sunlight, and he studied its growth behaviour under aerophilic conditions in a culture chamber where temperature, light-intensity and daylength could be varied. Unfortunately, this was almost a century ago, so there is not a single reprint left. Edenhofner,H.K & A.M. Schmid (1984) Effects of daylength and temperature-cycles on the growth of the aerophilic diatom Hantzschia amphioxys. Arch. Hydrobiol., 101, 73-88 Perhaps this is of some help, because we had listed also numerous refs. on aerophilic diatoms known up to then. Best wishes, Anna Maria Schmid, University of Salzburg, Plantphysiology Return-Path: <@AWIUNI11.EDVZ.UniVie.AC.AT:owner-diatom-l@iubvm.ucs.indiana.edu> >X-Sender: reaviee@darwin >Date: Tue, 16 Jul 1996 22:32:00 -0400 >Reply-To: Euan Reavie >Sender: Research on the diatom algae >From: Euan Reavie >Subject: aerophyllic taxa??? >To: Multiple recipients of list DIATOM-L > >Hello... >I have been finding Nitzschia inconspicua and Diatoma moniliformis in >abundance attached to macrophytes within the tidal region of the St. >Lawrence River (and rarely further upstream). Salinity (conductivity, >alkalinity) do not change significantly throughout the length I have been >sampling, however. Is there a possibility that these taxa are tolerant to >temporary exposure during low tide? Any ideas/references would be helpful. > >(BTW, none of the other environmental variables change downstream either) > >bye all... >__________________ >| | Euan D. Reavie >| ( | Biology Department >| ) | Queen's University >| ___(___ | Kingston, Ontario, Canada >| | |_ | K7L 3N6 >| | |_| | phone: (613) 545-6193 >| \_____/ | FAX: (613) 545-6617 >| | e-mail: reaviee@biology.queensu.ca >^^^^^^^^^^^^^^^^^^ > From frithjof@PI.NETWed Aug 14 13:13:12 1996 Date: Wed, 17 Jul 1996 11:01:28 PDT From: "F.A.S. Sterrenburg" To: Multiple recipients of list DIATOM-L Subject: Aerophilic taxa? Euan's questions regarding aerophilic taxa are perhaps a good occasion for some general discussion on the List. If only to see how many of you are still defending the Outposts of Science and how many are Living It Up in Foreign Lands - holidaying and whatnot. First, I am not entirely sure we can apply the term "aerophilic" here. As far as I can see, this is typically used by landlubber diatomists to describe diatoms growing on stones etc. Annemarie's reply concerning Hantzschia communities on top of lichens is highly representative. By the way: is the term "aerophilic" not misleading here in the sense that these diatoms do not really "love AIR" but rather: they are hardy beasts that can do without WATER for some time? Now consider the typical intertidal situation such as Euan describes. This is the sort of mucky, silty, oozy habitat I love, and what I find is that diatoms love it too. Euan mentions two species he finds in abundance, but some of these intertidal niches can have a very wide species spectrum indeed. At first sight, these species would seem to have two ecological properties in common: 1) resistance to exsiccation - but see further 2) certainly: wide osmotic tolerance. Starting with 2): a typical case is siltflats exposed at low tide. When they dry up, salinity increases rapidly and greatly. But during the several hours' exposure, the poor critters may well be deluged by a torrential freshwater shower too. Perhaps mucilage can protect them somewhat (see Diat. Res 4/1, pp. 143-150 for an extreme situation in the tropics), but for many common inhabitants of siltflats not endowed with mucilaginous tubes the osmotic surprise could well be considerable and they would need to be able to survive it. Now 1): do the diatoms indeed dry up in this case? Although mudflats run dry to our eyes, the film of water to a diatom would still represent a nice Olympic swimming pool. As Rex Lowe said at the NADS: think like a diatom. Many macrophytes remain moist too during exposure at low tide. To summarise: I'm not so sure we can extrapolate the "aerophilic" situation on land to the intertidal environment at all! From reaviee@BIOLOGY.QUEENSU.CAWed Aug 14 13:13:19 1996 Date: Wed, 17 Jul 1996 11:20:43 -0400 From: Euan Reavie To: Multiple recipients of list DIATOM-L Subject: Re: Aerophilic taxa? (sorry for spelling the first time... never needed this term before...) I'm getting some very helpful replies... What also shocks me about this situation is that macrophytes such as Potamogeton and Elodea (where I found the diatoms) can survive out of water as well... I would think that more than a film of moisture would be required for them. At any rate, here are bits of interesting replies: Diatoma moniliformis has also been found attached to macrophytes within the tidal region of the Gordon River in the World Heritage Area of south west Tasmania. Temporary (tidal) exposure tolerance is therefore likely. ref: Hodgson, D.A., Vyverman, W. and Tyler, P.A. (1996). Diatoms of meromictic lakes adjacent to the Gordon River, and of the Gordon River estuary in south-west Tasmania. Bibl. Diatomologica (subm.) Nitzschia inconspicua is mentioned by Krammer & Lange-Bertalot 1990 (Suesswasserflora von Mitteleuropa) as highly tolerant against changes in osmotic pressure and common in the supralittoral (also mentioned by Kuylenstierna, The Benthic algal vegetation of the Nordre Aelv estuary, Diss Univ. Lund 1989-90). from: HHillebrand@ifm.uni-kiel.d400.de Note that Helmut mentions tolerance to changes in osmotic pressure, just like Dr. Sterrenburg suggested. Hopefully I will have a chance to discuss this stuff in Tokyo! __________________ | | Euan D. Reavie | ( | Biology Department | ) | Queen's University | ___(___ | Kingston, Ontario, Canada | | |_ | K7L 3N6 | | |_| | phone: (613) 545-6193 | \_____/ | FAX: (613) 545-6617 | | e-mail: reaviee@biology.queensu.ca ^^^^^^^^^^^^^^^^^^