River Lakes
Some 30 km of the Havel and its lake-like expansions are located in the Berlin municipal area. The Spandau barrage weir, which has existed since before 1232, separated the upper Havel, including Nieder-Neuendorf and Tegel Lakes, from the lower Havel, including the Scharfe Lanke, Stössen Lake, Jungfern Lake and Great Wannsee. The Little Wannsee chain lies in an ancillary ice-age spillway, and includes the Little Wannsee and Pohle and Stölpchen Lakes. These bodies of water are similar both morphologically and hydrologically, and can be considered outflow or river lakes. The total area of the Havel lakes is more than 2000 ha, with Pohle and Stölpchen Lakes the smallest with 10 ha each, and Tegel Lake the largest with about 400 ha. All bodies of water mentioned were tested in the course of the Berlin ichthyological survey. The Havel lakes are among the Berlin bodies of water with the highest number of species of fish, with up to 24 species in some waters on the lower Havel, and a total of 31 fish species altogether. The large number of fish species in the river lakes has a number of causes. On the one hand, as mentioned above, there are both flowing and still water areas, so that in addition to the ubiquitously present eurytopic species, both lentic species (preferring still water) and lotic species (preferring flowing water) can find suitable living conditions. Moreover, despite major anthropogenic impairments, relatively variegated shore structures can still be found.
Apart from widespread structures of every kind (bung walls, footbridges, moorings etc.), there are also flat, weeded bays and reed-beds, which serve the fish as spawning grounds and their brood as growth areas.
In addition, eel, pike and carp are regularly stocked. The Havel waters are a waterway of the first order, i.e. they are used by professional navigation. Moreover, they are heavily used by professional and sports fishermen as well as by water-sports enthusiasts and relaxation seekers.
In addition to the Havel, the Spree and Dahme also have lake-like expansions. Along the Dahme are the Langer and Zeuthen Lakes and the Great Krampe. Seddin Lake is fed with Spree water through the Gosen Canal; the Spree flows through all the other bodies of water examined (Rummelsburg Lake, the Great and Little Müggel Lakes, Dämeritz Lake and the Bänke). The last-named lakes occupy an area of 952 hectares together, with their size ranging between 15.8 hectares (Little Müggel Lake) and 770 hectares (Great Müggel Lake). A total of 31 species of fish have been verified; the single bodies of water had counts ranging from six species (Rummelsburg Lake) to 30 species (Great Müggel Lake).
The bitterling has largely disappeared from these bodies of water; it has been attested only in the Great Müggel Lake. The strong occurrences of the Habitat-Directive species loach and asp in the Great Müggel Lake particularly deserve mention. For both species, the Great Müggel Lake is the main spawning area in Berlin. These species are particularly numerous here, and from here they also settle other inner-city bodies of water, such as the Spree. The river lakes located at the south-eastern edge of the city stand out for their variegated habitats. They still have extensive floating foliate plant zones (the Bänke), broad non-reinforced, near-natural shorelines (the southern and western shores of the Great Müggel Lake), and relatively extensive reed-bed belts (eastern shore of the Seddin lakes). The use of these bodies of water is analogous to that of the Havel lakes, although the burden due to sports boats is considerably lower. The Dahme till Schmöckwitz is part of the Spree-Oder waterway, and is used by professional navigation.
The species-poorest river lake between 2003 and 2013 was Rummelsburg Lake, where only six species of fish were attested.
Inland Lakes
The category of inland lakes includes closed, standing bodies of water with areas greater than one hectare. Depending on their type of genesis, the distinction is made between natural lakes (created by the Weichselian Glaciation), and artificial lakes (pits, gravel or clay quarries, peat cuts, etc.).
Natural Lakes
Thirty-one of the sampled lakes were assigned to this category. Their sizes ranged from 1.2 ha (Möwen Lake) to 70 ha (Gross-Glienicke Lake). A total of 25 species of fish were verified in them, with the number of species per lake ranging from two (Schwarzwasser Lake) to 15 (Koenig Lake).
The land-forming, flat, polytrophic Bogen Lake in the Buch Forest has an extensive reed-bed belt. The sewage-farm operation near the lake, which continued into the mid-‘80s, led to heavy nutrient immissions, causing it to silt up. In summer, the oxygen content of the water often reaches values critical for fish. From the south shore of the lake, there is a pipe connection to the Buch ponds. The lake appears very unspoiled.
The Grunewald, Hundekehl, Nikolas and Schlachten Lakes and the Krumme Lanke form the Great Grunewald lake chain. They are located in an ancillary postglacial spillway off the Havel lakes. The shores of these long bodies of water are overgrown with trees almost throughout their entire length. With the exception of Nikolas Lake, which has extensive herbaceous areas of flat water and reed-beds, the mentioned bodies of water have scanty reed-beds in only a few places. The Little Grunewald lake chain includes the Hertha, Halen, Diana, Hubertus and Koenig Lakes. Like the Great Grunewald lakes, they are located in an ancillary postglacial spillway off the Havel lakes. Their shores are lined with bushes and trees, and to some extent reinforced with wooden fascines. These bodies of water all have reed-beds and flat herbaceous areas. Their shores are accessible to the public only at a few locations. Like most Berlin lakes, they are also fishing areas, and as such are regularly restocked with fish.
With an area of 70 ha, Gross-Glienicke Lake is Berlin’s biggest inland lake. It is a stratified, eutrophic to hypertrophic lake. Its earlier, temporary connection to Sacrow Lake no longer exists, so that migration of fish via this path has ceased. Fish-stocking is carried out mainly with pike, tench, carp and eel; a total of eight species of fish have been verified. Due to a chemical phosphate precipitation project carried out in 1992-‘93, the summertime view depth has improved considerably in the lake, which has also favoured the settlement of sub-aquatic plants and led to a rise of the structural variety of the lake.
The long-drawn Hermsdorf Lake is located in the north of Berlin. It is drained by Tegel Creek. Like Heiligen Lake, its flow is too slight for it to count as a river lake. Its shore vegetation is variously structured; some areas are overgrown with reed-beds, others with bushes and trees. Flat, herbaceous areas which can serve the fish and their brood as spawning grounds and shelters are found in the water. The lakebed is muddy. Fourteen verified species have been attested in Hermsdorf Lake
The hypertrophic Malchow Lake is located in the north of Berlin. It is used for fishing. Its maximum depth is only 6.5 m; its view depth is only a few centimetres. The lakeside is partly lined with thick willow bushes (eastern shore) and trees (northern and north-western shores). Higher aquatic plants are largely lacking, due to the nutrient entry from the surrounding area; the western part of the lake is particularly strongly silted. Here, thick mud deposits extend to just below the water surface (10-20 cm). No fish kills have been observed during the past twenty years, as had repeatedly been the case between 1974 and 1988. The lake is managed and stocked with fish by the Berlin State Fishermen’s Association which belongs to the German Fishermen’s Association e.V (DAV). They have stocked catfish successfully, as could be impressively seen, among other things, by the catch of a 1.20 m long fish in the summer of 2003. However, only 12 species of fish are currently attested, compared with 14 to 1993 and 11 to 2003.
The hypertrophic Ober Lake in Hohenschönhausen is a park lake. The lake structure is poor except for an island, with monotonous concrete shorelines which offer fish neither shelter nor spawning grounds. From 2011 to 2014, an extensive lake rehabilitation project was carried out, including mud removal, shoreline rehabilitation and the installation of a lake filter. The goal of the measure is the considerable improvement of water quality. The lake is also managed by the Berlin state branch of the German Fishermen’s Association (DAV). The fish population has changed considerably compared with the period before 1993. At that time, crucian, gibel carp, tench and carp were frequent; by 2003, brusque and moderlieschen predominated, as they still do today. Particularly brusque have a much lower tolerance for oxygen scarcity than the cyprinids mentioned above. The number of fish species has declined to nine, compared with 14 in 1993 and ten to 2003.
Neighboring eutrophic Oranke Lake is also a park lake used for fishing; on its northern shore, there is also a heavily frequented public swimming area. The lakesides were reinforced with steel bung walls and concrete honeycomb plates, until these were removed in 2012 in the course of a shoreline renaturalization project. Extensive curltop growth, which provides the fish with spawning grounds and shelter, is still found in the lake, while the bathing beach provides sand-spawning (psammophilic) species of fish like the gudgeon with a suitable spawning refuge. The lake is fed from a submerged spring, is considerably less silted than neighbouring Ober Lake, and has a better water quality despite heavier frequentation by bathers.
Plötzen Lake in Wedding is also used for public swimming. The lake is also used for fishing.
The Plötzen Lake has predominantly non-reinforced shores; the tree stands reach the water. The only non-wooded shore is in the area of the public bathing area. Every year, large quantities of leaves from the shore vegetation fall into the water, causing nutrients to be released and oxygen deficiency to appear in the hypolimnion. At the time of the full circulation in October 2000, an eel kill occurred, so that in the fall of the same year, chemical methods were used intensively for nutrient fixing in the sediment. An examination of the consequences for the ichthyo-fauna carried out in subsequent year verified a total of 15 fish species (Fredrich & Wolter, not published) as opposed to 10 species to 1993. As of 2013, 13 species could be attested, including the eel.
Before the termination of fish farming in the Müggelheim Teufel Lake, it was stocked with fish by the DAV Berlin Branch. The species of fish verifiable at present are primarily the result of that programme. Like Plötzen Lake, the shores are largely tree-lined. The leaf entry caused by this has led to the polytrophic lake having a mud floor, with an up to 20 m thick layer of fine sediment.
The Teufel Lake in Wilmersdorf is located in a nature reserve. Its shores are lined with trees and to some extent with reeds. The result is a variegated structure and a near-natural appearance. The lake has a self-reproducing population of bitterling, one of very few in Berlin.
The shores of the Hermsdorf Wald Lake have thick stands of trees. There are flat herbaceous areas which are suitable habitats for broods and young fish and spawning grounds for fish which require aquatic vegetation. The lake appears very natural. A total of nine fish species are attested.
The Zehlendorf Wald Lake is not open to the public and also appears quite natural. The shores are thick with trees, with stabilized walkways in some places. Submerged aquatic vegetation is rich. Compared with 11 fish species in 1993, and eight in 2003, only seven were attested in 2013.
The hypertrophic Weisse Lake (in Weißensee) is a park lake managed by the DAV Berlin Branch, with a monotonous shoreline of old facines and few structures. Cyprinide species (carp) have hardly any spawning substrate, because strong eutrophication hinders higher water plants. The lake bottom is very muddy, except for the bathing area on the east shore. The water fountain in the middle of the lake introduces much oxygen in the summer months and is therefore to be seen as positive. After numerous fish kills between 1993 and 1996, only seven fish species were attested in 2003 and also in 2013, compared with 18 in 1993.
The drop in the numbers of species compared with 1993 in many inland lakes, seemingly so dramatic, can often be explained by the fact that the users, mostly fishing organizations, today apparently plan and carry out fish-stocking measures more responsibly. The species which are now missing in the lakes are almost exclusively those which were stocked in the past, although they were unsuitable for the particular body-of-water type. These included primarily rainbow trout, but also pike-perch, asp, chub etc., which are now disappearing once again, since the stocking measures have evidently been terminated. In the 900 fishing samples taken between 2003 in 2013 in Berlin, the rainbow trout was no longer found.
Artificial Lakes
This category includes nine of the lakes sampled. Their size varies between 0.5 hectares (Körner Lake) and 15 hectares (Habermann Lake). In them, a total of 23 species of fish were verified; each lake had at least four (Lasszins Lake), and at most 11 (Butz Lake, Fauler Lake, Neuer Lake). The high numbers of fish species can be explained by stocking.
The BUGA bodies of water on the terrain of the former Federal Horticultural Exhibition (BUGA), the Eastern Lake, the Main Lake, the Southern Lake and the Iris Lake, were created for the scenic design of the park. They are artificially fed. Their water is relatively low in nutrients, and clear. Parts of the shore region have been near-naturally designed and planted, and are home to a large number of plant species. Thick growths of submersed makrophytes grow in the water. Although numerous species of fish, including bitterlings, were stocked in these bodies of water, only eight are attested. The bitterlings have not taken hold.
In the Great Tiergarten, there are a number of park bodies of water which are in some cases interconnected by trenches, of which two, Faule Lake and Neue Lake, are classed as artificial lakes due to their size. Their water is supplied from the Spree, but this connection is not passable for fish, so that the still very high number of fish species, 11, compared with 18 until 1993 and 15 until 2013, is still largely due to stocking. A connection passable for fish from the Tiergarten bodies of water to the Spree, proposed by Wolter & Vilcinskas in 1993 has not been realized to date.
The Kaulsdorf Lakes, located in the borough of Hellersdorf, are a very recently created recreation area containing 5 manmade lakes, of which Butz and Habermann Lakes are the two oldest. The latter was built in 1942 in connection with the construction of the Reich Railway’s Wuhlheide detour track. The Kies ("gravel") Lake was not excavated until 1970; with a depth of 1-2 m it has a very shallow connection with Habermann Lake. A total of 13 species of fish are attested in the Kaulsdorf Lakes. Pike still find suitable conditions for natural reproduction in the lakes. Since, as a result of the loss of spawning grounds and thus restricted possibilities for its preservation, this species is largely present in Berlin due to stocking, so that the few remaining spawning grounds are particularly protection-worthy.
The former gravel pit Lasszins Lake is a near-natural body of water, protected and fenced in due to its significance for birdlife. The shore structure consists of a broad reed-bed belt and trees. A thick growth of submersed macrophytes exists in the clear, relatively low-nutrient water. Here, too, particularly the pike has suitable living and reproduction conditions.
Retention Basins
Retention basins are artificially created bodies of water. As their name implies, they serve as catchment, collection and sedimentation basins for rain and surface water. The run-off from roofs, courts, streets and other sources collected in these basins is heavily contaminated by nutrients and pollutants, particularly PCBs. The toxic sediments washed in do not reach the open bodies of water, so that rain retention basins contribute to the often demanded reduction of various nutrient and pollutant immissions into other surface bodies of water; they were conceived and designed for this purpose.
Due to the pollution of the water and the sediments which accumulate in the fish, these bodies of water may not be fished.Since retention basins can of course not be settled by fish either, they should actually be fish-free. The opposite is the case. For example, four fish species were attested in the Krötenteich ("toad pond") in Rahnsdorf.
Unlike the other retention basins, the Krötenteich was built as a survival pit for the fish from the Fredersdorf Mill Stream, the lower stretches of which periodically dry out. More than 14,000 fish from 11 species were counted in the mass fishing of approx. 250 sqm area survival pit carried out a 1999 (Fredrich & Wolter. unpublished). This included one single stocked catfish, for which both the basin and the stream itself are completely unsuitable as a habitat.
Small Bodies of Water (ponds, tarns, meres, kettle-holes and the like)
Ponds are artificial, dischargeable bodies of water. The other bodies of water were usually naturally created as a result of landscape processes during the Ice Age, including "dead-ice" lakes, and kettle-holes, or as abandoned clay or gravel quarries, or peat cuts. These bodies of water are different from ponds due to the fact that they are generally not drainable. Since no pond management is carried out in Berlin and therefore the ponds are drained only in the course of rehabilitation work, both forms have been categorized together. No further distinctions of the small bodies of water are required, either, from an ichthyological point of view in the examination area.
Their quality of inflow waters, anthropogenic impairments (mainly by fish stocking), and their areas (usually less than 1 ha) are all similar and make them comparable. In a total of 48 small bodies of water examined in Berlin, a total of 24 species of fish were attested, 18 of them indigenous. The average number of species per small body of water is four, which is very high, considering their small sizes. Only a few examples of these bodies of water are to be introduced briefly in the following:
With 13 fish species, Jungfernheide Pond is the small body of water which is richest in species. All fish species present here are indigenous.
Four of the small bodies of water examined had no fish species whatever. These are the Enten Pool and Sperling Lake in the Borough of Mitte, the Small Torfstich (peat dig) in Hermsdorf and the Röte Pool in Marienfelde
Eckern Pool is in the middle of a park in Tempelhof. Its shore structures are monotonous, regularly-formed reinforcements. Two species of fish were verified here – in 2003, there were five – all of them euryecoid species.
The Karow ponds are four hypertrophic former fish ponds in the fields of the discontinued Buch sewage farms. The ponds, interconnected by pipes, were used for fish farming until 1990, and are today a nature protection area. Their very unspoiled shores are lined with extensive reed-bed stands. Between 2003 and 2013, fish sampling was carried out in the Insel Pond and the Weiden Pond, and a total of six species were attested.
Streams
This category covers the Spree River in Berlin, small tributaries of the Havel and Spree, and the tributaries of the large lakes, all in all ten bodies of water which have however been listed as 13 water body segments for purposes of observation. All still show at least rudimentarily the near-natural habitat structures characteristic for streams, such as pools, meanders, back currents, turbulences, and various bottom sediments. Particularly overflow areas, coarse-grained sediment and meanders, all near-natural structural elements, have been removed almost everywhere by hydrological construction measures. This has led to a major elimination of those stream-dwellers which were tied to these structures. The strict protection of still-existing stream habitats as well as the restoration of some of those destroyed would constitute a very valuable contribution to fish-species protection. Other streams have changed markedly in their character, and have been heavily polluted by the discharges of sewage treatment plants. They are described under the category sewage-treatment plant discharge channels.
A total of 29 fish species occur in Berlin streams, including the crucian and the weatherfish, which are classed as "endangered" in the Berlin Red Data Book, and the burbot, bitterling, chub and dace. Only two of these species verified as occurring in streams are neozoa: the bullhead and the gudgeon.
The Berlin streams are home to an average of 14 different fish species. The pike and the roach occur in all waters investigated. The largest number of species was ascertained in Tegel Creek, with twenty 21 occurrences, all of them native. Below average numbers of species were found in the Fließgraben (13), the New Wuhle (11), and in the Kuhlake, the Lietzen Ditch and the Laake, each with ten species.
The feeding of mechanically cleaned Havel water into the Kuhlake has enabled the resettlement of submerged macrophytes, e.g., water-starworts and water milfoils, and also the water violet. The dense stands of plants favour the natural reproduction of the rudd and the pike.
The source of the Lietzen Ditch is located in the state of Brandenburg, west of the village of Schönow, near Bernau. The Lietzen Ditch drains the old sewage fields near Hobrechtsfelde, flows west past the Bogen chain of lakes, and empties into the Panke near the Karow ponds.
The Old Wuhle has its source in the state of Brandenburg near Ahrensfelde, and the New Wuhle at the former sewage treatment plant; these two branches flow together north of Cecilienstraße and then empty into the Spree near the old forestry station in Köpenick. The fish sampling operation was carried out in three ichthyological segments: First, in the New Wuhle, second in the Wuhle between Cecilienstraße and the "Wuhleblase" (the Wuhle above the drop structure), and finally between the Wuhleblase and the Spree (the Wuhle below the drop structure). After the shutdown of the Falkenberg Sewage Treatment Plant in 2003, extensive renaturalization measures were carried out in the Wuhle between 2006 and 2008. In addition to restructuring measures for weirs appropriate to fish and small animals, concrete and steel piling structures were replaced with near-natural stone row fish passages, and approx. 50,000 t of polluted mud were removed from the Wuhle and the Kaulsdorf Ponds. Moreover, the floor of the bodies of water was raised by up to 1 m, in order to counteract the often low level of the water in the Wuhle, and to attain groundwater stabilization. Other measures are planned (SenStadtUm 2013b). In der New Wuhle, a total of 12 species, 11 of them native, including the weatherfish, have been verified. In the two segments of the Wuhle, 16 native species, including the crucian in both cases, were likewise verified. In the section above the Wuhleblase, the weatherfish was also verified.
Canals
Canals are artificial waterways with monotonous, reinforced shores (ripraps, concrete or steel bung walls), largely constant breadth and depth, and usually with a mostly trapezoidal profile. Berlin has more than 100 km of canals, if the canal-like structures of the Spree River in the inner city areas are included. Fish make are present here only on seasonal visits or in migrations, because of the lack of structures important for them, such as spawning, shelter and feeding areas. The number of fish species present is thus affected by the fauna in the still bodies of water with which they are connected. In order to realize the good ecological potential in the Berlin canals in accordance with the EC WFD, it was required that 16 characteristic fish species occur (Pottgiesser et al. 2008). However, this good ecological potential was not achieved in any of the canals investigated. Currently, an average of only 10 species are verified in the Berlin canals.
The Gosen Canal, completed in 1936, connects Dämeritz Lake and Seddin Lake. Its shores consist largely of ripraps. Its mean depth is 3 m, its width 35 m. Aquatic plants are very rare in the canal; shore reinforcement measures as well as the impact of waves caused by ships are the assumed reason for that. Currently, 10 species of fish are verified in the Gosen Canal.
The canals in the city centre, such as the Landwehr Canal and the Kupfergraben, have been developed even more monotonously. For reasons of space, the shores are perpendicular here, and are solidly sealed. Thus, unlike the ripraps of other canals, they are not even usable as spawning substrata by hard-substrate spawners like the perch or the ruffe. A total of 20 species of fish were verified in the canals; the canal with the largest number of species was the Teltow Canal, the southern connection between the Spree and the Havel, which showed 16 fish species.
Trenches, Melioration Trenches
This category consists of small, hardly structured, largely straight artificial streams. They were mainly built as inflow and outflow trenches for the sewage farms, but also for drainage, e.g. of the Gosen Meadows in Köpenick. Their profile is trapezoidal or rectangular. While the outflow channels of the sewage farms are heavily contaminated by nutrients and pollutants, the pure melioration trenches, i.e. the irrigation or drainage trenches, are typically only polluted if their surrounding countryside is or was intensively agriculturally used. The abandonment of sewage dissemination and the drop of the ground-water table caused many of the trenches in the north of Berlin (the former Buch sewage farms) to dry out. A total of 20 trenches and melioration trenches were investigated between 2003 and 2013.
The Western Withdrawal Ditch (Westlicher Abzugsgraben) branches off from the Citadel Moat via a weir, and empties into the Havel below the Spandau Lock. There is a relatively strong current below the weir, and the sediment is sandy and gravelly. Further downstream, in areas of weaker currents, the floor is muddy. The banks appear near-natural, and are tree-lined almost throughout their entire length. A total of nine fish species have been verified. Without a doubt, the Western Withdrawal Ditch is a favourite spawning area for the fish of the Havel, especially for rheophilic species.
The Great Sprint Ditch is a strongly weed-clogged melioration trench connected with the Lübars pond. Both species of stickleback and the weatherfish were verified in it. With regard to ichthyological value and protection, it should be treated as equivalent to the sewage-farm trenches (see below). Maintenance measures may be necessary to prevent the overgrowth and hence the disappearance of this trench.
There are many discharge trenches around the discontinued Buch sewage farms, remainders of 100 years of such use. They are today dry during the summer because of the lowering of the groundwater table. Both stickleback species were found in almost all sewage farm trenches. They are the species most adapted to this kind of extreme biotope and find their last refuge areas here. Since the remained small trenches have been preserved, the populations of sticklebacks has during the last few years stabilized at a level which is low in comparison with the habitat supply prior to the extensive groundwater lowering, for which reason the endangerment level of both species has been reduced in the current Red Data Book (Wolter et al. 2003). In the Berlin Red Data Book for 2013, the nine-spined stickleback is on the "Preliminary Warning List" (a German category roughly equivalent to the international "near threatened" status), and the three-spined stickleback is non-threatened. Little trenches are typically only settled by two or three fish species. This number can, however, increase considerably if the trenches are connected with rivers or lakes and are used as spawning and breeding areas by the species inhabiting the latter.
Sewage-Treatment-Plant Discharge Channels
In the 2014 Edition, only the Neuenhagen Mill Stream (Erpe) is listed as a sewage treatment plant discharge channel. Since the shutdown of the Falkenberg Sewage Treatment Plant in 2003, the Wuhle, which had served as a discharge channel there, has, in later editions been listed as a stream.
With 23 species, including 20 native ones, the Neuenhagen Mill Stream (Erpe) has a very high number of species. These include such endangered species as the bitterling and the chub, as well as the loach, which is classified is extremely rare in Berlin. In 2010, it was verified in the state of Berlin for the first time since 1920.
Seven native species, including the crucian, occur in the Neuenhagen Mill Stream (the segment in Bellevue Park, the old Erpe).