GMU:Life in an aquatic ecosystem/Ecosystem of the pond in Ilm park

From Medien Wiki
January 2025, Collecting sample from the pond2

The ecosystem of the pond we investigate is located in the Ilm Park, that is a 48-hectare landscape park on the edge of Weimar's Old Town. It was gained from nature and further shaped between 1778 and 1828. The park contains valuable trees, mostly local varieties (Some imported from southern Germany), but also some foreign trees, especially from North America; bushes were also planted.


The Ponds

The ponds in the Park are in two different categories: They are formed either by running water (Pon1) overflowing from underwater supplements into puddles or by rainwater collecting (Pond2). The running water is clearer and deeper and it's surface is more open to the light. It has watergrass on the surface, and we have found Dracunculus medinensis worm and Cyclops in it.

Approximate location of the ponds

In our research, we initially studied both ponds and compared them together.

We selected the rainwater pond for educational purposes and analyzed the microbiomes collected from various depth of the pond and at different times throughout the winter.

As temperatures dropped, we observed a decrease in algae count in all the samples collected from various areas of the pond.

Collecting samples from different part of the Pond2 in the Winter 2025

In January, the pond had significantly more water than in autumn, which may contribute to increased algae growth, as they tend to rest and produce less in cold weather.

During winter, most leaves decomposed into organic matter, exposing the surface. This lack of cover no longer protects algae from excessive sunlight, cold, and small animals. 

As a result, we observed that the number of algae around the edges and beneath plants is significantly higher than in other areas, such as the pond's center, which faces greater temperature fluctuations, freezing, direct sunlight, water currents, and less food. The muddy parts are too dark and thick for algae to thrive or receive adequate light.

Additionally, both the clear areas and muddy sections of the pond have fewer microbiomes in autumn and winter, both. Whereas, in general we found more organic matter and microbiomes in the shallow parts of the both pond, particularly around the edges, where the water is less clear.

In these areas, algae can likely settle during colder weather, as they have access to food that remains stable despite water currents, allowing them to thrive in an environment with more consistent temperatures.

PH of both ponds are relatively similar and neutral.

Testing PH


Plants

The abundant trees above the pond drop their leaves onto the water's surface, creating a richer, warmer, and safer environment for microbiomes, which contributes to higher algae concentrations.

Based on the leaf shape, there are many chestnut trees surrounding the pond. (American Chestnut; American or Allegheny chinkapin, also known as "dwarf chestnut"/ Castanea Pumila)

The Chestnut Trees leaves covering all of the surface of the pond Oct.2024

furthermore, from the Hight and the smoothness of the Chestnut tree’s barks, (The smoother, the younger) we can say they have been probably planted there since the park was built; maybe dislocated them from the southwestern Germany, because they generally belong to the warmth- and light-loving tree species. On the other hand, the fruit contains a lot of minerals and vitamins such as Magnesium, Copper, Iron, Potassium, Folate, Protein, Calcium...that are the best source for food.

>> 1-3. Trunk of the Chestnut Trees: Shows the old age, 4. The part of the soil around the pond is drying up; dark, lightweight and moist

Also, their seeds can naturally be rooted better in water, where the soil is so soft and they have time to make roots. So, we can observe more young Chestnut trees were used to be a part of the pond recently, compare to other areas that has been dried up long time ago.

dark dirt: The parts that are already dried up, but still have a visible border, showing the past size of the pond

The soil around the area is a dark built-up mud and light-weight, showing it has been a part of the pond before it dried up, while a tick layer of decomposed leaves is on top of it. You can almost observe the borders of the dried up bigger pond.

It has been likely connected to the other pond on the other side of the road, long time ago before it dried up.

Another observation is, a lot of common Sunburst Lichen on the tree barks and branches.

>>1. Moss, and 2.Lichen on the branches
collecting and check samples from the pond1(left) and 2 (right): In Winter there was more microbiomes in the sample from the pond1, we found Daphnia, Diatom and Chlamydomonas
Water meal sample from the pond2
Poa Parenesis, grass around the pond
Wood Avens
finding leaves of the Bald Cypress Tree near the pond


            

Wildlife

There are a vast variety of wild life in Weimar, which a lot of them live in the parks and natural areas; Birds such as Eurasian Blue Tit, Carrion Crow, Eurasian Jay, Great Tit, Goldcrest, Hawfinch, common Merganser, Green Woodpecker, European robin, Mute Swan ...

Small animals like Eurasian red Squirrel, European Toad,

Insects like European firebug, Forest Bug, Brown Marmorated Stink Bug, Asian Lady Beetle, Black Oil Beetle, Common Blue butterfly, Common Carder Bumble Bee, ...

We observed several of them, also checked the sound with the app BirdNet


https://ebird.org/region/DE-TH-WE/bird-list?yr=cur

https://www.inaturalist.org/places/weimar