Ephemeral wetlands a race against time for aquatic Pedersen, Ole

Published in: The Aquatic Gardener

Publication date: 2018

Document version Publisher's PDF, also known as Version of record

Citation for published version (APA): Pedersen, O. (2018). Ephemeral wetlands: a race against time for aquatic plants. The Aquatic Gardener, 31(2), 15-20.

Download date: 11. okt.. 2021 VOL31 NO2 APR—JUN2018 THE AQUATIC GARDENER

JOURNAL OF THE AQUATIC GARDENERS ASSOCIATION TAG VOL31 NO2 APR—JUN2018

2 From the President 28 Immersing Myself in the 5 On PAR 2018 Global Pet Expo 11 Great Aquashops 33 Meet the AGA—Jen Williams 15 Ephemeral Wetlands–A Race 34 Competitive Aquascaping Against Time for Aquatic Plants 38 Aquatic Plants Without Water–It’s 21 Two Compositions with Red Easy and Useful! Stem Plants

ON THE COVER Walking in the Park by Chen Meng Chun. 2017 AGA International Aquascaping Contest Dutch category 2nd place winner.

SENIOR EDITOR Cheryl Rogers AGA Membership [email protected] PO Box 51536 Denton TX 76206 USA. TECHNICAL EDITOR Karen A. Randall [email protected] Payments to the AGA are not deductible as charitable contributions for US Federal income DESIGN Jen Williams tax purposes. AGA International [email protected] The Aquatic Gardener ISSN 1073-6999 AGA PURPOSE To disseminate information REPRINT POLICY: Reproduction of original ar- about aquatic plants, to study and improve Aquascaping Contest ticles appearing in The Aquatic Gardener (TAG) upon techniques for culturing aquatic and may be allowed under certain circumstances. bog plants in aquariums and ponds, to Please contact the Senior Editor or visit our increase interest in aquatic gardening, and to Showcase your aquascape with hobbyists web site for specific reprint requirements. promote fellowship among its members. from around the world! DISCLAIMER: Opinions expressed by the AGA Membership/Renewal Rates authors are their own and do not necessarily US/Canada/Mexico: reflect the opinions of The Aquatic Gardener OPENS June  1 yr $22 2 yr $40 3 yr $56 or The Aquatic Gardeners Association, Inc. Other Countries: CONTRIBUTIONS: Artwork, photographs 1 yr $25 2 yr $46 3 yr $65 CLOSES September  and articles are welcome from any source (Includes airmail for TAG) RESULTS and may be submitted to the Senior November  Membership includes four issues of this Editor for consideration. We request first periodical each year. To join or renew, visit publication rights for articles accepted. Please Rules, info and entry at www.aquatic-gardeners.org/member.html or contact [email protected] for showcase.aquatic-gardeners.org mail a check or money order (in US funds) to: submission guidelines. 1 Thanks to national growth, in 2016 water will be a world leader when it the Pzes online store was created opens in May of this year. (pzes.es), shipping premium quality The future of Pzes? Who knows fish and plants. In addition, during where we will be in a few years, but the last year, we decided to take a little by little we will implement the new leap and expand the store in idea that we always had in mind: to downtown Madrid. The new venue foment and respect nature, to learn has a more modern and minimalist from it and to grow affection for design and facilities that offer the hobby in Spain and the rest of a different shop without losing the world. the essence of Pzes: an elegant exhibition hall, a meeting place and a space to hold workshops that promote respect for nature and design underwater. This space was inaugurated by Masashi Ono and Takayuki Fukada in February 2018. EPHEMERAL WETLANDS– This year Pzes participated in the A RACE AGAINST TIME FOR AQUATIC PLANTS creation and implementation of by Ole Pedersen, University of Copenhagen, Denmark what is now the largest Natural Aquarium in Spain, located on the Photos by the Author premises of Loroparque on the Some of our most popular aquarium countries. This kind of climate is island of Tenerife. An aquarium 10 plants grow in natural habitats characterized by mild winters and meters long and 18,000 liters of where water is in short supply. In hot, dry summers and the majority extreme cases, seeds germinate of the annual precipitation falls and develop into flowering plants during winter. In areas with hard, within weeks in order to complete compressed soils, excess rain their lifecycle before the water accumulates in shallow depressions disappears. In the present article, of the landscape to form wetlands I provide some striking examples that exist for weeks to months from ephemeral wetlands in depending on how fast the water Western Australia hosting species evaporates. In the early summer, of Glossostigma, Marsilea and the evaporation can exceed 10 mm Isoetes, which are all well-known per day in Western Australia when genera in our planted aquaria. temperature soars to 40°C (104°F) Ephemeral wetlands, i.e. wetlands and the wind picks up. Plants existing for just a short time, inhabiting such ephemeral wetlands are common features in areas must be ready to grow from spores with Mediterranean climate such or seeds whenever the opportunity as California, Argentina, South arises, and then it is a race against Africa, Western Australia and time to complete the lifecycle so obviously also the Mediterranean that a new cohort of spores or

14 15 seeds can be produced to enable water, i.e. more than 25 cm (10”), but persistence in the environment. often the plants do not flower until Needless to say, ephemeral the water recedes. Once the plants wetlands also host a unique fauna become air-exposed, they start that has to overcome the same flowering and most are pollinated challenges; good examples are by insects. The fruit (capsule) species of killifish where many eggs develops quickly and the seeds require partial desiccation (drying are released as both sediment out), a kind of diapause, to restore and plants dry up completely (see further development of the embryo. the series of photos). One species We are using a range of aquatic of Glossostigma, G. trichodes, plants from ephemeral wetland produces a peduncle that is up to in planted aquaria. One of the 10 cm long to support its flower

floating upon the water surface < < most widely used is the genera A shallow ephemeral wetland A dense submerged (yes, the to enable insect pollination even of Glossostigma and several in Western Australia. The water is so clear that it seems though the is growing of these are from Western evaporation can be as high as that these plants are growing in relatively deep (10 cm is in fact Australia. Glossostigma is used 10 mm per day so within a few air) population of Isoetes australis. rather deep when the plant itself as a foreground plant or to form weeks the water is entirely gone. The tiny leaves are no longer than dense carpets in tanks inspired by is no more than 5-10 mm tall). It is essential that the plants 20-30 mm and the dispersal unit the Nature Aquarium concept of See Pedersen et al. (2009) for complete their life cycle in order to (spores) are formed in sporangia Takashi Amano. Glossostigma is a nice example of G. trichodes secure the next generation in this on the basal part of each leaf. a so it germinates growing side-by-side with Isoetes spectacular habitat. australis in a vernal rock pool in > from seeds when the environmental Time is up! The moisture is gone,

Western Australia. > conditions are suitable. The minute It is a race against time! The soil and the sediment is totally dry. purple or blue flowers self-pollinate Glossostigma can also form dense is cracking but still moist and the The only living organism left in populations that thrive in deep mats in natural wetlands both flowers are struggling to complete are the seeds of Glossostigma because the seed density can the seed production in order to drummondii. The seeds are small > Emergent population of flowering be extremely high–and they all secure the next generation of and light, they are very tolerant to Glossostigma drummondii but germinate at the same time when Glossostigma drummondii in desiccation and thus they form an in between leaves of Marsilea sp. the moisture comes back to the this habitat (a vernal rockpool in ideal dispersal unit. are also seen (the spatula- system–but also because they Western Australia). shaped leaves). form runners and thereby spread very efficiently by vegetative reproduction. Glossostigma cleistanthum has been recorded in North America although it is native to Australia and New Zealand. G. cleistanthum has invaded natural wetlands of low pH, low alkalinity, low phosphorus and thus waters with high transparency. It is highly competitive and it threatens

16 17 species of Elatine forming the natural vegetation, but the various are the sporangia. In the sporangia, storage organ for starch and it is natural vegetation of these lakes species of Elatine are no bigger the meiosis occurs where spores used by Isoetes to enable survival (Les et al. 2006). When I first than G. cleistanthum, so if the latter are formed with only one set of during times where the ponds it heard about these observations grows a little bit faster, is a little chromosomes. The spores are tiny, is inhabiting dries up for a shorter 10 years ago, I was surprised that more competitive and maybe also most tolerate extreme desiccation time. During desiccation, the leaves such a pretty little and fragile less susceptible to diseases and and therefore these are excellent and roots are wilting and the corm plant could cause any harm to the grazing, it may only take a few plant dispersal units, just like seeds in also shrinks but once the water generations until the newcomer has angiosperms (flowering plants). comes back into the system, new outcompeted the native vegetation. The unique thing happens now! leaves and roots are formed and Lesson to be learnt: make sure When the spore “germinate,” the plant can fully recover within that you never contribute to the they give rise to a whole new days. Nevertheless, once the water unintended spreading of aquatic generation of plants with only dries up for a long time, the spores plants. This website lists a number of one set of chromosomes. Often, are the only units that enable ways to prevent exactly that: http:// this generation is inconspicuous survival between years. www.sleloinvasives.org/10-ways- and consists of a flat green, Species of Marsilea are similar help-stop-spread-invasive-species. photosynthetic thallus not much except that they do not possess

< larger than a few square millimetres. a corm. But in contrast to Isoetes, The water has almost disappeared In addition to flowering plants, Nevertheless, this structure they spread extremely fast by form this population of Isoetes ephemeral wetlands also produces male and female organs vegetative runners. In the aquatic australis. The sediment may remain host interesting species of where the reproductive gametes form, the leaves normally only moist for another couple of days but pteridophytes that are widely used are produced. The male gametes consist of spatula-shaped leaves then it is all over unless the water in planted aquaria. Examples are look like sperm since they are but intermediates between aquatic comes back within a few weeks. If species of Isoetes and Marsilea motile unicellular cells and they so, this species has a trick–it can both belonging to spore plants, and terrestrial leaves can also be need water in order to swim over produce new roots and leaves from i.e. plants reproducing by spores formed under water and these often to a female egg cell where the its storage organ, the corm. rather than seeds. Pteridophytes look like a clover leaf. When the are exciting in that they “still” have fertilization takes place. Once > > A population of Isoetes australis two independent generations in the fertilization is successful, Species of Marsilea with the typical that is doomed! Unless the water their respective lifecycles–one the new diploid sporophyte aquatic leaves under water and comes back in a few weeks, this with one set of chromosomes (two sets of chromosomes) new leaves looking like clover population has to start all over (haploid) and one with two sets starts growing directly out of emerging into the air. These leaves from the beginning with a new of chromosomes (diploid). It is the the female reproductive organs have stomata and do not desiccate generation of sporophytes formed diploid generation that we use in and the haploid gametophyte (a when exposed to air due to the from the haploid generation. planted aquaria and the diploid plant producing gametes) dies. protective layer of wax, the cuticle. plants reproduce by spores; hence, The cycle is complete! The point the diploid generation is also called is that we rarely observe the sporophytes (plants that produce thalloid gametophyte whereas the spores). The spores are formed sporophyte is the “real” plant that in fertile clusters on the leaves– we know from our hobby. maybe you know the phenomenon In the case of Isoetes, the from ferns that often are littered sporophyte consists of roots, with small, brown dots on the leaves and a corm. The corm is lower sides of the fronds; these a swollen stem that can act as a

18 19 pond dries up, the whole plant dies Isoetes or Marsilea.) In summary, the and it has to start over from spores reason why these pteridophytes are once the water comes back into so common in ephemeral wetland the system. However, both species is because the spores are very have in common that they have an tolerant to desiccation. inconspicuous haploid generation Plants from ephemeral wetlands that most people have never are popular in planted aquaria for seen. (In fact, I have never seen two major reasons. 1) the aquarium the haploid gametophyte of either plant nurseries love plants that can be grown as emergent individuals because algae are much easier to control in emergent cultures compared to submerged and 2) these plants are often opportunistic, fast-growing plants and this is something we all like. Fast-growing plants are less prone to getting covered by algae (think < Submerged species of Marsilea about Anubias where the older with the spatula-shaped leaves. leaves always tend to look sad Marsilea is growing side-by- as they accumulate more and side with a dense population of more algae). Glossostigma (the bright green Interzoo, the world’s largest pet leaves in the background). fair, took place in May in Germany > Marsilea is under severe time and a large proportion of the plants pressure! The water is receding in the stunning display tanks was TWO COMPOSITIONS WITH RED STEM PLANTS so fast that it cannot keep pace indeed originally from ephemeral by Aqua Design Amano and produce the new aerial leaves wetlands. Translated by Tomoko Schum Photos by Aqua Design Amano (clover-shaped). Most leaves are The shape of a composition is with mound shape composition and aquatic leaves (spatula-shaped) LITERATURE an important element in Nature another with triangular composition. and these will desiccate within Les D.H., Capers R.S. & Tippery the next few days. N.P. (2006) Introduction of Aquarium for the refinement of a The above photo is a layout with a Glossostigma () to layout. A composition is produced mounded composition produced North America: a taxonomic and by placing driftwood and stones, using gracefully-shaped branches ecological overview. American and planting aquatic plants. Red of Branch Wood and the bright, Journal of Botany, 93, 927-939. stem plants are helpful for making red color of the stem plants. While Pedersen O., Pulido C., Nicol D., a well-defined composition with the the open spaces in the left and the Winkel A. & Tuckett R. (2009) strong impact of their color. In this right sides of an aquarium are a vital Vernal rock pools - nature’s own article, we are going to discuss the part of a mounded composition, a nano aquaria. The Aquatic Gardener effective use of red stem plants small open space was also created Vol. 22 #4, pp. 34-43. using two different aquascapes: one in the center to give a sense of

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