Lednické rybníky NNR (The Lednice Fishponds) was declared in 1988 and covers a territory of 557.53 ha at elevations of 160 – 175 metres. The reserve includes the network of fishponds Nesyt, Hlohovecký, Prostřední and Mlýnský rybník on the alluvial plain of the Včelínek stream between Sedlec and Lednice as well as the Zámecký rybník on the alluvial plain of the Dyje river near Lednice in the Jihomoravský kraj - South Moravian Region. The main subject of the protection is the importance of the fishpond complex as one of the most significant ornithological localities in the Czech Republic, providing nesting sites and migration stopovers for many bird species.
The substrates consist of Flysh of the Žďánice Unit, Miocene sediments and smaller areas of Pliocene sands and gravels. The soil cover on the banks of the fishponds is mostly typical fluvisol or gleyic fluvisol, while muddy gleysol can be found on the banks of the Mlýnský rybník pond. The banks of Nesyt pond are covered with psephitic fluvisol. The Zámecký rybník pond was built on loam-dominated Quaternary sediments, with typical chernitzas around the pond edges. The chernitzas around the Zámecký rybník are of a gleyic character while on the banks of Nesyt pond they are of a pelic character passing into poorly developed solonchaks.
Narrow fringes of bush-like or tree-like willows and poplars grow along the banks of the fishponds and also in shallow waters where streams flow in the ponds. Reedbeds formed mostly of common reed (Phragmites australis) and lesser bullrush (Typha angustifolia) border these bankside growths and stretch for varying distances into the ponds, depending on the water depth. In the ponds we can find lesser pondweed (Potamogeton pusillus) and fennel pondweed (Potamogeton pectinatus), as well as aquatic species like horned pondweed (Zannichellia palustris), ribbon-leaved water plantain (Alisma gramineum), the water crowfoot Batrachium rionii and brackish water crowfoot (Batrachium baudotii), mare’s-tail (Hippuris vulgaris), brookweed (Samolus valerandii). When the ponds are periodically drained, growths of swamp pricklegrass (Heleochloa schoenoides) and whorl-grass (Catabrosa aquatica) develop on the exposed fishpond bottom. Some cultivated, non-indigenous species (e.g. water lilies) can also be found in the Zámecký rybník pond. The Lednice fishponds are also characterised by their algae communities of naturally eutrophic stillwaters. The presence of species such as the Diatom Epithemia sorex indicates that the water is polluted and the blue-green algae Phormidium ambiguum and Nodularia harveyana can also be found in the ponds.
The fishponds are an important nesting site for many waterbirds and the largest nesting colony of the grey heron (Ardea cinerea) and night heron (Nycticorax nycticorax) in the Czech Republic is found on the islands in the Zámecký rybník with up to 230 pairs of both species. Other nesting species include the red-crested pochard (Netta rufina), bearded tit (Panurus biarmicus), marsh harrier (Circus aeruginosus) and sometimes the bittern (Botaurus stellaris). The Lednice fishponds are also an important migration stopover for greylag goose (Anser anser), pochard (Aythya ferina), shoveler duck (Spatula clypeata), black tern (Chlidonias niger) and several species of waders. The white-tailed eagle (Haliaeetus albicilla) regularly overwinters here. In the past the avocet (Recurvirostra avosetta) and the spoonbill (Platalea leucorodia) occasionally nested on the ponds. The amphibians include the edible frog (Rana esculenta), common toad (Bufo bufo) and green toad (Bufo viridis) and the common tree-frog (Hyla arborea). Many significant butterfly and moth species live in the reedbeds, including the fen wainscot (Arenostola phragmitidis), Chilo phragmitellus of the Crambinae, small China-mark Cataclysta lemnata, the Pyralid moths Calamotropha paludella and Sclerocona acutella and Webb’s wainscot ( Archanara sparganii).
Until recently the fishponds in the Včelínek stream catchment were used very intensively for fishfarming, which had the negative effect on the water quality of the ponds (strongly eutrophised water due to fertilising the ponds). This situation was worsened by the eutrophised water flowing into the ponds as most of the municipalities in the catchment did not have sewerage works. Therefore the ponds partly acted as sedimentation reservoirs and there were several cases where botulism killed large numbers of birds. Problems were also caused during the 1970s when the Včelínek catchment ponds were connected by an irrigation canal from the Dyje river, which allowed the pond water to be used for irrigation, but also brought a different type of water, which led to the degradation of the ponds vegetation and also allowed a high water surface level to be maintained and the regular pond estivation in the summer was stopped.
On the Lednice ponds there are permanent problems with recreational usage. The Zámecký rybník pond lies within the Lednice Chateau park and the popular path from the Chateau to the Minaret leads along its banks. On the SE bank of the Mlýnský rybník pond a recreational area with a campsite, restaurant and swimming area is in operation, but the owners and tourists sometimes have problems in complying with the protective regime. The Prostřední and Hlohovecký rybník ponds are also used for recreational activities (without permission) but so far there are few negative effects. Currently we are succeeding in renewing the regime of partially draining the ponds in summer and also in lowering the intensity of fish farming on the ponds. The pumping of water for irrigation from the ponds has stopped as it is no longer economically viable. Problems are also caused by the spread of invasive fish species, especially the “silver crucian carp” (Carassio auratus gibelio).
The fishponds on the Včelínek stream plain were built by the Lichtenstein estate in the 15th century, and at the beginning of the 19th century the banks of the Hlohovecký, Prostřední and Mlýnský rybník ponds were landscaped as part of the chateau park and many exotic tree species were planted around them. At this time a number of romantic buildings such as the Hraniční zámeček lodge, Rybniční zámeček lodge and the Temple of Apollo were built in their vicinity. The Zámecký rybník pond with its irregular banks and several islands was built in the 19th century and is located within the English Park directly behind the Lednice Chateau. The park and pond which offers views from the chateau to the Minaret is one of the most popular attractions in one of the most visited historical monuments in South Moravia. The whole Lednice – Valtice estate with its ponds and unique landscape and architectural monuments was declared a World Cultural Heritage Site under the patronage of UNESCO in 1997.