Phytotelma

Dendrotelme

A phytotelma (plur. Phytotelmata, more rarely also phytotelma, from the Greek  φυτόν , "plant" and τέλμα , "puddle") is a tiny body of water that forms in a recess of a living land plant . The water mostly comes from the rain , more rarely it is actively excreted by the plant .

Types of Phytotelmata

Water- filled bromeliad funnel

A distinction is made between the following types of Phytotelmata:

• Knotholes in trees of different species ( dendrotelme )
• Bamboo stems that are hollow and in which rainwater can collect if the sprout breaks or is cut off.
• Leaf axils can also sometimes contain significant amounts of rainwater. Examples are domestic in Central Europe carding or the Central American heliconias .
• Bromeliad funnel : many bromeliad plants (Bromeliaceae) form funnel-shaped rosettes of leaves in which water collects.
• Cauldron traps in carnivorous plants ( Nepenthes , Cephalotus , Sarracenia, etc.) form jar-shaped leaves into which prey animals can fall and cannot climb out. The kettle contains a liquid that, in contrast to the other Phytotelma types, is mostly produced by the plant itself (exception Sarracenia and related genera) and often contains digestive enzymes .

Living conditions in Phytotelmata

• Phytotelmata are basically distributed worldwide, but only in regions with sufficiently high rainfall. In Central Europe you can find mostly water-filled knotholes. The age of Phytotelmata can vary greatly. Knotholes have been continuously observed for more than ten years. The body of water in bromeliad funnels is also likely to last as long as the plant lives. In contrast, leaf axils and pitchers of carnivorous plants only last about one vegetation period , but sometimes they dry out much earlier. The size of Phytotelmata varies extremely. Leaf axils or the traps of small carnivorous plants often contain hardly 1 milliliter of water, large pitchers of the carnivorous pitcher plants ( Nepenthes ) often contain several liters, and large knotholes up to 100 liters.

The water in Phytotelmata is initially mostly nutrient-poor, as it comes from rain. Over time, dust or dead leaves fall into it, or animals drown in the pitchers of carnivorous plants. The water therefore becomes more and more nutritious over time. The temperature of the water is subject to extreme fluctuations, as the small amount of water quickly absorbs or gives off heat. If the water is very warm, it can also become very low in oxygen.

In tree holes and bamboo stalks, the plant has no noticeable influence on the composition of the water. Bromeliads and carnivorous kettle-trap plants, on the other hand, actively extract nutrients from the water for the plant's nutrition. For this, carnivorous plants often secrete enzymes , detergents , acids or radicals in their pitcher liquid in order to digest their prey more quickly. Dissolved slime can sometimes be found in the leaf axils.

The inhabitants of the Phytotelmata

Phytotelmata are colonized by a large number of organisms, the spectrum ranges from bacteria and fungi to insects, mites and small crustaceans to tadpoles . Only the insects are really well researched today. The composition of the community is determined by several factors:

• Settlement : The inhabitants must be able to reach the Phytotelma. Bacteria, fungi, algae, primitive animals and other very small organisms probably only get into the phytotelma by chance, as spores are blown by the wind or cling to leaves that fall into the phytotelma. Flying insects or frogs whose larvae develop in the phytotelma, on the other hand, actively seek out their habitat. Sometimes they unintentionally carry off flightless Phytotelma residents from one Phytotelma to the next.

• Survival : The residents must be able to survive in the nutrient-poor, but often enzyme-rich water of the phytotelma, they must be able to endure strong temperature fluctuations and be able to use the limited sources of nutrients. For example, bacteria eater can only migrate successfully when enough organic material has accumulated in the phytotelma to enable bacteria to grow; Predators can only survive if there is already a sufficient population of prey, etc.

• Competitiveness : In young Phytotelmata mostly all organisms survive which fulfill the above condition. With increasing age of the habitat there is more and more competition between the different species , which can lead to extinction again. It was shown, for example, that fly larvae that were placed in jug traps by scientists were almost all killed and eaten by the long-time residents within a very short time. Intraspecial competition has also been described, among others in the poison dart frog Ranitomeya reticulata intraspecial territorial behavior was observed. It is used to monopolize phytotelms as reproductive resources in which the tadpoles grow.

• Distribution : a successful Phytotelma species must finally be able to leave one Phytotelma and colonize a new one.

In total, several hundred species have been described as inhabitants of Phytotelmata. The following groups of organisms are of particular importance:

• Bacteria : Bacteria live in every phytotelma; they not only feed on organic matter that falls into them, but also partially carry out photosynthesis. Some of them can bind nitrogen from the atmosphere, which then benefits the host plant that formed the phytotelma. Well-supplied phytotelmata contain at least 100 million bacteria per milliliter.
• Fungi : Yeasts are omnipresentin the pitchers of carnivorous plants; together with bacteria, they are involved in breaking down the prey. Taller, thread-like mushrooms are less common. In many cases they also attack the plant that formed the phytotelma and then act as pathogens. Some fungi also live as parasites on animals that inhabit the phytotelma. Many types of fungus are able to grow in a phytotelma, but cannot form spores under water and thus cannot reproduce.
• Protozoa are also found in most phytotelmata, with the possible exception of the pitcher of some carnivorous plants, which produce overly aggressive digestive enzymes. These are mostly common species that also colonize polluted water; the genera Bodo , Cercomonas , Colpoda and Peranema are particularly common.
• Rotifers : in addition to many species that end up in Phytotelmata by chance, there are also some that are adapted to this special habitat, such as Habrotrocha rosa in the carnivorous plant Sarracenia purpurea
• Fly larvae are probably the largest group of Phytotelma inhabitants. Many species specialize in this habitat. As a rule, the larvae develop in the Phytotelma, the adult animals live terrestrially. Since flies are usually good fliers, pregnant females can easily find a new phytotelma and lay their eggs there. When the female flies leave their home phytotelma after hatching, spores of bacteria and fungi or eggs of rotifers or mites often stick to them, which are deposited in the next phytotelma when they lay eggs.
• Tadpoles : Many tropical tree frogs lay their spawn exclusively in phytotelmata, often in the funnels of bromeliads. This way you avoid ever having to leave the treetops. In the traps of the carnivorous plant Nepenthes ampullaria , more than 100 tadpoles of the pea-sized frog Microhyla nepenthicola were foundin less than 100 ml of liquid.
• Ostracods of the genus Elpidium were described by Fritz Müller in 1880from epiphytic Bromeliaceen from Brazil.
• In addition there are algae , nematodes , annelids , other small crabs , mites , dragonfly larvae , caterpillars , amphibious ants and many other groups before.

Of these many species, however, only a few are always represented in each individual Phytotelma. A phytotelma with more than six insect species is already considered to be very species-rich; similar numbers should apply to other animal groups. But the number of individuals can be very high. Thus, about 400 rotifers in a single case of Sarracenia not uncommon.

Phytotelma ecology

As small as most of the phytotelmata are, they still offer space for different organisms with different requirements, so they contain several ecological niches . The essential ways of life are listed here:

• Autotrophy : Phytotelmata hardly ever contain green plants; so there is little photosynthesis. Their share in the total energy supply of a phytotelma is probably a few percent at most. If there are plants, they are mostly green algae , blue algae or Kryptophyta ; in exceptional cases, higher aquatic plants or mosses can also occur. However, photosynthetic bacteria may be common .
• Herbivory : Since there are only a few plants, herbivores do not play a special role. Sometimes, however, amoeba feed on algae that grow in a phytotelma (own observation). There are also organisms that eat away at the walls of the phytotelma, i.e. the plant in which the phytotelma is located. However, sooner or later these organisms destroy their own habitat as the liquid then leaks out.
• Saprophagy : The majority of the Phytotelma inhabitants live either from organic matter (dead leaves, fly ash, drowned animals, etc.) that falls into the Phytotelma, or from bacteria that break down this substance. Within this group, a distinction is made between filter feeders , which filter the finest particles out of the liquid, micro-detritus saprophages , which eat slightly larger particles, and macro-detritus saprophages , which eat roughly entire carcasses.
• Predators : Predators mainly feed on the detrivores, so they can only live in Phytotelmata, which already house a large number of animals. Depending on the hunting strategy, a distinction is made between detritus predators that crawl or lurk around the bottom of the phytotelma in dead organic matter , sessile predators that are stuck on the wall of the phytotelma and wait for prey that swims by, and surface predators that lurk for animals under the surface of the liquid that fall into the phytotelma and free-swimming predators that actively swim around.
• Top predators are at the end of the food chain and eat saprophages and smaller predators; they are therefore mostly the largest organisms in the phytotelma. A distinction is made here between free-swimming top predators , ambush hunters and semi-terrestrial top predators , who live amphibiously and only visit the Phytotelma for hunting.
• Egg-eaters : Frog tadpoles that develop in Phytotelmata would often find too little food here. The mother of the genus Oophaga named after it lays further, unfertilized eggs at regular intervals, which serve as food for the tadpoles.

The food chains in Phytotelmata are usually relatively short and contain at most three links (sarcophagus - predators - top predators); in young or species-poor Phytotelmata one usually only finds one or two-part food chains.

Despite the small size of the Phytotelmata, two or more species with similar needs can often coexist by ingeniously dividing resources. In the cauldrons of the carnivorous plant Sarracenia purpurea, for example, there are three species of fly larvae of animals that fall into the trap. The first, Blaesoxipha fletcheri , eats the prey while it is still floating on the surface of the liquid. The second, Metriocnemus knabi , continues to eat as soon as the dead animal has sunk to the bottom of the trap. When eating, however, many small particles are detached from the corpse, which are filtered out of the liquid by the third fly larva, Wyeomyia smithii . The latter also eats bacteria and protozoa.

Phytotelmata as a model system of ecology

Phytotelmata are sharply demarcated microbiotopes that are often only a few centimeters in size and often only have a life expectancy of a few weeks. In contrast to “normal” ecosystems, you can easily study their entire development. It is also very easy to carry out experiments, such as adding or removing species. In addition, the number of species that occur is quite manageable. That is why ecologists are increasingly using phytotelmata as model systems to test theories on species immigration, competition, food chains and webs, etc.

See also

• Zoo hotelma

literature

• L. Varga: An interesting biotope of the biocoenosis of aquatic organisms. In: Biologisches Zentralblatt , Volume 48, 1928, pp. 143-162.
• RL Kitching: Food webs and container habitats. The natural history and ecology of phytotelmata. In: Cambridge University Press , Cambridge 2000, p. 431.
• JH Frank, LP Lounibos: Phytotelmata: Terrestrial plants as hosts for aquatic insect communities. Plexus Publishing, New Jersey 1983, p. 293.
• DS Srivastava, J. Kolasa, J. Bengtsson, A. Gonzalez, SP Lawler, TE Miller, P. Munguia, T. Romanuk, DC Schneider, MK Trzcinski: Are natural microcosms useful model systems for ecology? In: Trends in Ecology & Evolution , Volume 19, 2004, pp. 379-384.
• HTW Tan, PKL Ng: Digestion and early succession in the pitcher-fluid. In: HTW Tan (Ed.): A guide to the carnivorous plants of Singapore. In: Singapore Science Center , Singapore 1997, pp. 132-138.
• Fritz Müller : Aquatic animals in treetops: Elpidium bromeliarum . In: Kosmos , Volume 4, Leipzig 1880, pp. 386–388, PDF .
• Fritz Müller: Descripção do Elpidium bromeliarum, crustaceo da familia dos Cytherideos. In: Archivos do Museu Nacional do Rio de Janeiro , Volume 4, Rio de Janeiro 1881, pp. 27–34, Plate 2, PDF .
• TJ Little, PDN Hebert: Endemism and ecological islands: the ostracods from Jamaican bromeliads. In: Freshwater Biology , Vol. 36, No. 2, 1996, pp. 327-338.

Individual evidence

1. ↑ P. Werner: Habitat use by poison dart frogs in the Amazonian lowland rainforest in Peru . In: elaphe , Volume 18, No. 4, 2010, pp. 15-19.
2. ↑ Indraneil Das, Alexander Haas. New species of Microhyla from Sarawak: Old World's smallest frogs crawl out of miniature pitcher plants on Borneo (Amphibia: Anura: Microhylidae). (PDF) In: Zootaxa , Volume 2571, 2010, pp. 37-52.