katrinteubner

the great subtropical lake in the Yangtze river basin with large seasonal water level fluctuations

Poyang Lake, 2011:
Even in the dry season the lake is an important waterway. Large vessels are still able to navigate the narrow channel in early spring before the flood season.Poyang Lake, 2011:
The area of the 'open lake' is rather narrow in the dry season. Large vessels build an 'off-shore island'.

Poyang Lake, 2011:
This small fishery port at city Xingzi is the northernmost site described here for Poyang. In the background of the photo the unique rocky island with temple buildings called the 'Fallen Star Pier' is seen. Poyang Lake, 2011:
Large areas of the lake sand banks are above the water in early spring, at the end of the dry season before the rain in May.

Lake Poyang (29°7’31.1''N, 116°16’39.7''E) is at seasonal periods of high water level (Liu et al. 2016 R), i.e. in summer and autumn, the greatest freshwater lake in China. The shallow lake is located 4-10 m above sea level, in the Jiangxi Province. The lake is mainly surrounded by large floodplain wetlands and  is thus also the largest lake-wetland area in the country.
The water level of Poyang changes by seasonal flooding by up to 14 m (personal communication, spring 2011). According to the 16 month study from September 2011 to December 2012 by Liu et al (2016) R, the annual water level fluctuation was 11 m, with a seasonally varying water level from 8 to 19 m. Poyang in winter looks mainly like a river delta, flowing around wide sand bank areas (dry season); in summer, Poyang turns into a large lake (wet season). Poyang hence passes transient stages of a river and lake ecosystem every year.

The description on this website refers to the northern part of the lake only. It further relates to the navigable main channel trough the lake – this was actually the only way possible to carry out field sampling by boat during this visit in dry season. The northernmost location described here is the fishery port at the city Xingzi. The small port is close to the historical spot of a miniature of the rocky island with temple buildings, called the ‘Fallen Star Pier’ (29°26’10.17''N, 116°1’42.59''E), which is located on the west shore of the lake. The series of lake photos shown in the gallery starts at this point and is going south. After passing a rather narrow navigable stretch with wide dried-out sandbanks on the east shore, a noticeable landscape point appears, a hill with a park of wind turbines (gallery photos 20 and 21). Here Poyang looks like a lake even in the dry season. Going further south on the lake, again the narrow navigable main and side channels were passed during the lake sampling journey. The three wetlands that are described by their vegetation covered in the text, are also introduced from the north to south. The photos of the third wetland, called on this website ‘matured wetland’ are taken from the most southern part of this sampling journey.

Poyang Lake, sand banks above water, 2011:
In the dry season large areas of sand river banks are above the water. The yellow colour indicates the pure sand without a large lake sediment surface layer (no significant amount of 'organic mud' is covering the surface).
Poyang Lake, sand banks above water, 2011:
The same as the left photo, but an area with more lake sediment containing detritus ('organic mud').

Poyang Lake, sand banks above water, 2011:
'Ploughed' sand - footmarks of livestock indicate grazing on the wetland down to the water's edge.Poyang Lake, sand banks above water, 2011:
Crystal-clear water at the water's edge of pure sand banks - suspended solids (silt, mud) deposit rapidly as turbulences are low in the calm shoreline zone.

The photos on this website were taken from two sampling journeys in 2011, at the end of April and in early May. They are hence showing the lake during the dry season. Colleagues commented that after ‘heavy rain for more than one week’ by the end of May in that year, Poyang had been filled up and looking ‘like a real lake’ again.

The water regulation of the lake has been changed with the construction of the Three Gorges Dam that was completed a few years ago (see Yangtze S on this website).

Poyang Lake, water's edge in the dry season, 2011:
Round pebbles and pieces of grey clay are found on the sand bank of the illustrated site of the 'matured wetland' (see description of vegetation for the wetland below). Poyang Lake, water's edge in dry season, 2011:
Horizontal layers of fine particle sizes are seen on the water's edge, i.e. of sand and lake sediment material. The sharp soil edge is not shaped by environment but human activities. It is due to dredging (maintenance of the navigable channel) and further undermining by water waves when vessels pass the navigable stretch. Sand dredging vessels are seen left in the background.

Poyang Lake, water's edge in dry season, 2011:
Eroded horizons as described for the photo above right, but of rather grey clay color. Poyang Lake, water's edge in dry season, 2011:
Groynes are constructed perpendicular to the lake bank in some sections of navigable narrow stretches.

poyang: the shallow turbid lake serves as habitat for many organisms from aquatic microbes to molluscs, snails, shrimp and fish

Poyang Lake, phytoplankton net sampling, 2011:
A 'Ruttner'-sampler is used to take the water sample from the lake surface layer. The water in the glass tube of this sampler looks turbid yellow-brownish. In addition to non-filtered samples for water chemistry and phytoplankton estimation, five liters of lake water are passed through the plankton net of 10 µm mesh size (see net below the sampler). This sample is called the 'net sample' (see also text).
In this subtropical lake, gloves must be worn while sampling to avoid skin contact with the water and hence an infection with parasitic trematodes (schistosomiasis, bilharzia). The water transparency is low (Liu et al 2016 R), mainly due to large concentrations of inorganic suspended solids (silt) similar to the high turbidity of water in the lake Taihu (Chen et al. 1993 R and 1993 R; also this website S) and the Yangtze River (this website S). The low water transparency can be easily seen when a glass is filled with the lake water as a ‘Ruttner’-sampler (see photo leftside). The mixing of water column and flow keeps the inorganic particles of silt and clay suspended. In the case of low water movement (see photo of crystal-clear water in the introduction about shores with sand banks), the particles deposit and the lake turns from turbid water to clear water if no other particles such as floating algae further reduce the water transparency.
The results of conventional measurements of chemical, physical and biological parameters according to the standard method for lakes will not be sufficient to understand such a turbid aquatic ecosystem. The picture of the crystal-clear water at the calm water’s edge but the muddy water a few centimetres outside the channel, just illustrates the high spatial resolution and also the dynamic in such a turbid lake (see photo above and gallery photos 38-40). Lake processes, which usually occur primarily at the sediment-lake water interface or on the shoreline on biofilms, are ‘translocated’ to the water column by free-floating particles in Poyang. These suspended solids (silt and associated matter) provide a large surface area, ‘a place to live’, and serve as a micro-habitat for attached living micro-organisms, in the main for bacteria, but also for algae. High-resolution measurements in space and time of biota-environment interactions might enhance the understanding about such a 'mobile' micro-habitat. The importance of other micro-habitats as ‘marine snow’ (‘lake snow’) and ‘biofilms’ has been discussed in other studies for particular aquatic ecosystems. Furthermore, silt can physically adsorb chemical compounds for a certain period. The capacity of transient adsorption of ions, as nutrients like phosphate, will affect the turnover of essential nutrients in such a turbid lake. Finally, the suspended solids definitely reduce the availability of light needed for photosynthesis. The underwater light climate in Poyang might primarily favor low light or shadow adapted phytoplankton species such as diatoms and cyanobacteria (see also the blooming of diatoms in spring and autumn and various taxa of cyanobacteria involved in blooms in spring and summer, which are described for shallow, well mixed turbid water bodies of so called 'riverine lakes', on the website about Grosser Mueggelsee S). The low-light regime might be mainly responsible for the inhibited growth of algae, which results in only low biomass of phytoplankton in Poyang whatever the actual potential for algal growth by enhanced nutrient availability in Poyang is.

Besides the mentioned ecological aspects of high amounts of suspended solids in the water, methodological problems analyzing the water in such a turbid lake arise. Devices measuring fluorescence for a rough estimation of ‘algal biomass’ in lake water, for example, are developed for water bodies where turbidity is primarily determined by floating photosynthetic micro-organisms, the phytoplankton organisms. In the case of brownish water bodies such as Poyang and Taihu, the measure suffers from a too high background from inorganic solids and the relative low fluorescence signal from phytoplankton. Phytoplankton samples are also difficult to observe under the light microscope as the many inorganic particles distract from the few algae occurring in the sample. Here, a separate analysis of two size fractions of phytoplankton can be recommended. It is worth mentioning that small algae (less than 10 µm) are commonly more frequent in a lake water sample than large algae (greater than 10 µm). In water bodies without the dominance of colony-forming cyanobacteria, the small cell size fraction of 0-10 µm contributes more than 50% to the total chlorophyll concentration of phytoplankton (Teubner et al. 2001 R). The small phytoplankton species can be enumerated among the plentiful silt particles under the microscope when a small sample volume is carefully observed at high magnification (microscopy on a non-filtered phytoplankton-water sample). In addition, a sample might be taken using a net of 10µm mesh size to eliminate silt particles (even more appropriate would be a net of 5µm mesh size). In this net sample, the relatively rare but large phytoplankton species are enriched, making it suitable for quantitative microscopical analysis. In addition to the phytoplankton biovolume estimation by microscopical counting, the chlorophyll-a concentration of the non-filtered water sample might be analysed. The results of both measures, of the 'tricky' phytoplankton biovolume and of the 'simple' chlorophyll-a extraction (Greisberger & Teubner 2007 R) , might correspond to each other, i.e. might validate each other.

The shallow muddy lake is not only the habitat for floating microbes but also for many aquatic animals. The photos below illustrate some species of molluscs as snails and mussels; and fish mainly found on the 'sand bay wetland' site. The photo of the lost catch from fishers shows small fishes and various species of shrimp that are common in Poyang. Fish and shrimp are sought not only by fishermen but are also the preferred food for the finless porpoise (see more details about this species described in the following two sections, the 'habitat of finless porpoises' and the Poyang resource 'use by people').

Poyang Lake, animals living in the lake, 2011:
The remains of shells of mussels on this rock far from the recent shore mark the much higher water level in the wet season compared to the dry season when this photo was taken. Inset: Detail of shells of the mussels.Poyang Lake, animals living in the lake, 2011:
Various shells of mussels and snails are shown, which were found on the water's edge of the wetland of the 'sand bay wetland' and the matured wetland site' (see also the vegetation found at these wetland sites described below). The snail shown in the inset right is Bellamya aeruginosa, the snail in the small inset top left Parafossarulus striatulus. Further a common mussel species in Poyang shown in the two small insets left below is Corbicula flumine.

Poyang Lake, animals living in the lake, 2011:
The shell of the large mussel species (middle of the photo) can be more than 25 cm long. To compare the size, small shells of Corbicula flumine are seen top left on the photo. Poyang Lake, animals living in the lake, 2011:
Stranded dead animals are found on the shore.

Poyang Lake, molluscs and fish, 2011:
Remains of a fish dried in the air.
Poyang Lake, animals living in the lake, 2011:
Lost catch of small fish and various shrimp species found at the small fishery port of the city Xingzi.

poyang lake:
the habitat of the finless porpoise (Neophocaena phocaenoides)

The finless porpoise, jiangzhu, also called the ‘river pig’, is systematically close to whales and dolphins. During a field sampling trip by boat early May 2011, these animals could be identified by their characteristic leaps from the water. Two series of snapshots shown below illustrate such leaps. The leaps were sometimes seen nearby in front of the boat, but the porpoises were too close and fast to follow this scene with a simple digital camera. The leaps documented in the snapshot photos could be taken only by a ‘leap-panorama view’. These low-resolution snapshots don’t really capture the excitement of the moment when seeing the porpoises leaping, but these photos are sufficient to document that these animal species live in this lake.

Watching porpoises on the Poyang Lake, 2011:
A leap of a finless porpoise (Neophocaena phocaenoides) is shown by a series of snapshots. In the background a large vessel in front of the landmark of the 'hill with the park of wind turbines' can be seen. Watching porpoises on the Poyang Lake, 2011:
The same as the left photo but another leap of probably the same individual.

Watching porpoises on the Poyang Lake, 2011:
The water in-between the fishermen just handling their nets & cages and the old dredging vessel, a finless porpoise was seen – may be attracted by the fisher’s business, looking around for catching a lost fish??? As mentioned in the text, the simple digital camera was too slow to catch this scene with the porpoise - the animal is NOT seen in this photo. The sampling boat was not going along the busy navigable waterway through the lake but rather the shallower lake areas. The sampling tour began in the morning and returned in the early afternoon, lasting about two hours in one direction, going from the Poyang field research laboratory station at Xingzi (Poyang Lake Laboratory for Wetland Ecosystem Research station of the Chinese Academy of Sciences, PLWER of CAS) to the south. During the two-hour one way trip about these animals could be counted leaping about 40 times; and on the boat sampling return journey way about 30 times. Sometimes an individual animal was seen by a series of leaps; at other moments the leaps indicated that these animals have formed a small group near the water surface. The finless porpoises were most frequently seen in the more open lake area, where the ‘river channel’ broadens up near to the ‘real lake’ at the ‘hill with the park of wind turbines’ (details in the introduction above), about 30 minutes away from the field research laboratory station. Furthermore some leaps were seen in the narrow ‘river channel’ in the south, onward leaving the main stretch, on a side stretch without sand dredging vessels and where less frequent cargo vessels were passing (two photos below). One finless porpoise was even seen nearby in the fishery harbor, the reach at the station of PLWER (see title of the right text photo).

Poyang Lake, habitat of finless porpoises, 2011:
Shallow shore areas of curling water, looking like a small eddy surrounded by rapids, were the common places visited daytime by the finless porpoises. Many leaps of these animals were counted at such near shore habitats in late April/early May. Poyang Lake, habitat of finless porpoises, 2011:
On this concrete shallow shore area of rippling water, actually in front of this herd of water buffaloes bathing on the shore, leaps of a number of finless porpoise were seen.

Poyang Lake, habitat of finless porpoises, 2011:
This buoy made by a plastic bottle marks the position of underwater fish nets or fish traps. The shallow water is an attractive fishing ground for fishermen needing to earn their living. It is, however, also the preferred ground visited by finless porpoises getting food. Gill nets can become a dangerous trap for these rare animals.
Poyang Lake, habitat of finless porpoises, 2011:
Leaps of finless porpoises were even seen near large vessels in narrow navigable stretches - but not in the close neighborhood of noisy sand dredging vessels often operating in clusters on the lake.

poyang wetland: the vegetation cover differs among the marshland sites

Impressive large wetlands surround the water zone of the Poyang lake system. The vegetation covering the seasonal wetlands is probably best seen at the end of the dry period. Three wetland sites are illustrated by photos and have been visited during two vegetation surveys, at the end of April and early May in 2011. The sites briefly described here are called: the wetland at the 'Fallen Star Pier', wetland at the 'sand bay', and the 'matured wetland'. In addition to the photos in this paragraph, the three sites are illustrated by the gallery photos 8-13, 36-51 and 62-69, respectively.

The seasonal wetland at the small rocky temple island (‘Fallen Star Pier’) at the city Xingzi, is a large bay of ‘grass land’ during the dry season. As described in the paragraphs below about the resource use of Poyang, this wetland was used as pasture. During the vegetation survey, a herd of less than 80 cattle was seen grazing on this large bay area. Browsing damage by cattle was only found in some marginal areas and mainly on grass of Poaceae (e.g. Phalaris arundinacea) and a few plants of sedge-grass (Cyperaceae; see also sustainable use of grass-land pastures in the catchment of alpine lakes in Austria described on the website about lake Attersee S).

The most impressive species of the native vegetation on this wetland was Beckmannia syzigachne. This gramineae plant (Poaceae) was forming larger dense monospecific stands in the more central part and the still moist areas of this marshland.

The wetland inhabited further some temporary small water basins and streambeds. The bottom of these shallow-water basins was densely covered by the submerged macrophyte Potamogeton crispus (not shown here by a photo). The recently dried-out marshes of these ‘wet-spots’ were only sparsely covered by terrestrial vegetation. The yellow flowering composite plant, Lapsana apogonoides, was here growing in association with some short sedge grass (Carex spp.).

At the margin of this wetland, or on the elevated rocky ground of the island of the ‘Fallen Star Pier’ some plants commonly growing on rather dry and ruderal fringe habitats, as e.g. the pink flowering laminate plant Leonurus cardiaca (Lamiaceae), were found.

Poyang Lake, 2011:
The seasonal wetland that is surrounding the small rocky island of the 'Fallen Star Pier' Temple is popular for a walk in the dry season. This meadow is also used as grazing ground. The east side of the wetland is bordered by the lake. The Poyang indicated by large shipping vessels is seen on left side of the photo. Poyang Lake, 2011:
View from the Temple of the ‘Fallen Star Pier’ in the dry-season wetland and the lake. The historic Pagoda, which is part of the temple complex on the island, is built of stone. The small fishing port is seen in the center of the photo in the background. The city Xingzi located on the ridge, can be seen further left. The modern city has contemporary and traditional housing areas. A narrow alley with old wooden residential houses and buildings that are over 200 years old, is not far from the fishing port.

Poyang Lake, wetland at 'Fallen Star Pier', 2011:
Wetland in early May, before the flood season. This tall hygrophilous 'grass' vegetation is built by dense stands of Poaceae (mainly Beckmannia syzigachne, rarely Phalaris arundinacea) and some few plants of Cyperaceae (diverse Carex species). Poyang Lake, wetland at 'Fallen Star Pier', 2011:
Dense stands of the sludge grass Beckmannia syzigachne.

Poyang Lake, wetland at 'Fallen Star Pier', 2011:
The yellow flowering composite plant Lapsana apogonoides growths together with short reed of Carex and Poacaea.
Poyang Lake, wetland at 'Fallen Star Pier', 2011:
A few plants of Leonurus cardiaca growing close to the rock of the island indicate the rather dry than moist habitat conditions in this narrow place surrounded by the wetland meadow.

The second site described here is further south from the noticeable landscape point, the hill with the park of wind turbines (see above in the introduction). This 'wetland at the sand bay' was created by sand dredging on the shore. On the water's edge, pure sand due to erosion occurred. On the water-saturated marsh of the bay, species like Alopecurus aequalis, Ranunculus sceleratus (see photo below), Polygonum hydropiper (see gallery photo 44) and Echinochloa crus-galli, were found. Further land-side dense stands of various Carex species and yellow flowering composite Gnaphalium affine dominated the wetland. With less moisture, stands of larger forbs as of Artemisia selengensis, and the grass Phalaris arundinacea covered the wetland. A few plants of Cirsium arvense and Apiaceae occured sporadically among the higher forbs. The wetland seemed to be commonly used as a pasture. Browsing damage by cattle was mainly found on the short grass (Poaceae, see plant right side of the gallery photo 46). Planted trees finally delineate this wetland, which is the land-side further continued by a meadow.

Some plants found on this wetland are known to be edible plants. Young apical sprouts of Artemisia selengensis are well-liked for vegetable dishes. Gnaphalium affine is popular for tea but also edible, as students told. Further it was said that the spikes collected from Alopecurus aequalis and similar species of this genus on marshes provides a valuable 'chicken food'. These few examples are mentioned to convey that the wetland is a popular area visited by local people.

Poyang Lake, wetland at sand bay, 2011:
Sand dredging formed this bay of pure sand ground, containing no lake detritus (popularly called 'mud') on the water's edge.Poyang Lake, wetland at sand bay, 2011:
Short lived small forbs as Alopecurus aequalis (Poaceae) seen in the front right of the photo, built up the sparse pioneer vegetation cover of the marshland.
Inset: The yellow flowering Ranunculus sceleratus (Ranunculaceae) was collected from this mash habitat during the vegetation survey.

Poyang Lake, wetland at sand bay, 2011:
The perennial reed on 'middle-aged' wetland is built by various species of Cyperaceae (e.g. Carex spp., see hair-like leaves) and Poacaea (e.g. Phalaris arundinacea seen here by broad leaf blades).  A single terminal spike is typically found for the single-spike species group of Carex spp.-species and can be easily overlooked. Poyang Lake, wetland at sand bay, 2011:
The less water saturated wetland on the lakeshore is characterized by taller forbs: the yellow flowering Gnaphalium affine and Artemisia selengensis (see non-flowering stems middle and left side) are both composite plants and are popular as edible plants. They grow here in association with dense stands of 'grass plants' as of Carex spec. (hair-like leaves, Cyperaceae) and Phalaris arundinacea (broad grass leaves on the right, Poacaeae).

Poyang Lake, wetland at sand bay, 2011:
Dense stands of tall forbs mainly by Artemisia selengensis and Phalaris arundinacea that succeded on the further dried habitat of the wetland. Inset: Artemisia selengensis, young shoots of this plant are edible. Here, however, the whole plants were harvested for analysis in the lab.
Poyang Lake, wetland at sand bay, 2011:
Planted trees close to the lake shore will foster the dry-out of the marshland and hence promote the shrinking and the loss of valuable wetland habitats in the land-water ecotone of Poyang.

The third wetland site is named here the 'matured wetland'. Different from the sandy shoreline of the 'wetland at the sand bay', pieces of clay were common on the shore of this wetland site (see shoreline photo above about 'the water's edge in dry season'). As described before, Poacea with a short growth cycle (as e.g. Alopecurus aequalis)mainly settled on the moistore marshland. Going further land-side the wetland cover changed to stands of short Carex,  continued by a meadow of Carex associated either with Astragalus sinicus and Gnaphalium affine or with Artemisia selengensis (see text photos below about the 'matured wetland site' with dense vegetation stands). On the more distant elevated bank, a meadow vegetation was mainly built from rather taller Poaceae as e.g. by Festuca spp..

Poyang Lake, matured wetland site, 2011:
Zonation on the shoreline from the water's edge to marsh vegetation. Tufts of a sedge species (Carex spec.) are seen in the front right of the photo. Poyang Lake, matured wetland site, 2011:
Soil erosion at the water's edge - it is the most vulnerable zone for vegetation on the lake shore: Small ephemeral flowering plants are able to germinate, grow and form seeds during their very short life, lasting days to weeks in the dry season in early spring before flooding the marshes.

Poyang Lake, matured wetland site, 2011:
The pink flowering legume plant Astragalus sinicus (Fabaceae) is commonly found together with yellow composite Gnaphalium affine (Asteraceae) and sedge Carex spec. Poyang Lake, matured wetland site, 2011:
Dense stands of perennial forbs as of Artemisia selengensis and Carex spec.

Poyang Lake, matured wetland site, 2011:
The habitus of Gnaphalium affine looks here very similiar to that of the species Helichrysum arenarium, commonly found on sandy ground in Northern Europe. Further, a panicle of a tall grass of Poacae,  'Deschampsia' -like is seen.
Poyang Lake, matured wetland site, 2011:
Meadow with Gnaphalium affine and Astragalus sinicus among grasses as of various species of Cyperaceae (Carex spp.) and Poaceae (Festuca spec.). 

Besides higher plants also algae and cyanobacteria may occur on soil. The sandy loam in the Poyang marchland is the habitat of the soil cyanobacterium Nostoc commune. This colony forming cyanobacterium is easy to find on soil surface during the wet season. The colonies survive even the dry season and look then like algal paper. It is an edible cyanobacterium and usually harvested after rain, when the colonies are swollen (see morpho-cytology and chemical composition of Nostoc commune used as human food in Briones-Nagata et al. 2007 R; it is popularly also described as 'edible alga' or 'algal food' even it is not alga but a cyanobacterium; see also Nostoc commune in the gallery photos for the pond Biotop Auersthal S). The gelatinous colonies need to be washed carefully before being boiled or fried (to be cleaned from sand and soil). Seasoned with spring onion or garlic the Nostoc commune dish is served with rice in China. Some other cyanobacteria such as other colonial Nostoc species found in freshwater habitats and Spirolina grown in cultures can also serve as human food and supplementary food, respectively (see more details about cyanobacteria on the page Lab View S). Other taxa of freshwater cyanobacteria, however, such as Microcystis (see Dianchi S, Grosser Mueggelsee S, Taihu S), Anabaena, Aphanizomenon (see Bergknappweiher S), Cylindrospermopsis raciborskii (see Old Danube S) and Planktothrix rubescens (see Ammersee S and Mondsee S) are not food as they are known to be able to produce cyanobacterial toxins.

Nostoc commune; Breakfast at Poyang research station, 2011:
Food - prepared dish with Nostoc commune. Inset: The cyanobacterium was locally harvested from soil near the Poyang shoreline.
Nostoc commune; Breakfast at Poyang research station 2011:
Food - dish with boiled Nostoc commune seasoned with leaves of spring onion.

poyang - the large lake-wetland system: the use by the people

The lake use of Poyang is manifold and refers here to fishery, agriculture, raw building material extraction and navigation shown by photos on this website.

Gillnets and fish traps shown below and also shrimp fishing enabled to harvesting of even the small size animals of various small fish and diverse shrimp species. A photo of such a small fish catch is shown in the gallery by photo 7 and the text above in the section 'animals in the lake'.

Poyang Lake, local fishery, 2011:
Gillnets are put out in the shallow water. Poyang Lake, local fishery, 2011:
Fisher boat with net of small mesh size to catch small animals of fish and a various shrimp species common in this sub-tropical lake.

Poyang Lake, local fishery, 2011:
Waterfowl have a rest on bamboo constructions of gillnets & fish traps. Poyang Lake, local fishery, 2011:
Gillnets and fish traps on the shallow lake bank are covering the range of short-time water fluctuation.

The lake-wetland area is commonly used for livestock grazing. Even the quality of food differs with habitat conditions for vegetation growth on the wetland; many floodplain areas in the north of the lake are used as a pasture. Usually the number of cattle in a herd is small. For example, about 80 animals only were grazed on the larger floodplain bay-area at the 'Fallen Star Pier', which indicates a sustainable use of the wetland. Seasonal herding of about 100 water buffaloes could be further seen on wetland pasture. The herd was moving along the shoreline of the navigable channel.

Poyang Lake, 2011:
Livestock grazing on the wetland, here shown for cattle on the seasonal marshes at the rocky island of the ‘Fallen Star Pier’. Poyang Lake, 2011:
Livestock grazing on the lakeshore: A herd of water buffaloes bathing in the shallow lake zone.

The scenery of traffic in dry season, on the ‘Poyang-river', can be described on narrow stretches by a few small fishermen boats, many operating sand-dredging vessels and plenty of large cargo vessels passing the ship channel.

Sand dredging is now a common business on the lake. Dredging seems to have been done to maintain navigable channels, at least in periods of very low water level in the dry season. Furthermore, tons of sand are needed to satisfy the great demand in the current construction industry. On this side, lake Poyang is used as an important source for extracting sand and clay from the underwater lake banks. On the other side, sand dredging in Poyang has a definite impact on the ecosystem. 'Newborn' bays are created, and shape niches for biota connected to the lake along the channel. A channel with integrated small bays will increase the diversity of the habitat structure in the lake, might stimulate the growth of biota that benefits from low flow velocity and less washout. This biota might be different from biota growing well in the main channel. The sand bays will be successively inhabited as pioneer habitats. The settling of biota from bacteria to algae and small animals, however, proceeds not 'over night' but takes longer, proceeds successively over a time of weeks or even months. The settling of these pioneer habitats cannot proceed faster than the life span or the generation time of these individual organism groups is. In turn, sand dredging destroys the 'matured' habitats that are important as spawning and nursery feeding grounds. The balance between the creation of new structures being processed by the biotic life-activity to become a ‘new habitat’, and the harsh deterioration of 'matured' habitats (spots of life) will answer the question: What is the impact of sand dredging on aquatic biota in Poyang?

Another impact of sand dredging on the ecosystem comes by noise pollution. An old 'small' sand-dredging vessel is shown in the gallery (photos 59&60). The new dredging vessels are much bigger and have much larger sand dredging capacities. These vessels are often operating in clusters on the lake. In addition, the high capacity of extracting sand requires a likewise high capacity for the transportation of sand. Many large vessels ready to be loaded are therefore accompanying the bulk of sand dredging vessels. The operating of dredging vessels, the busy loading of vessels and navigation, and in-between further some small boats related to this business - have changed the silent place of the lake to a busy noisy motor-waterway. The noise pollution impacts above but also under water nearby habitats. The many vessels are narrowing the channel, in particular, in the dry season and are shrinking in this way the space to live for fish and finless porpoises. Leaps of finless porpoises were seen in less busy narrow channels, as e.g. northward 100 m away from the small fishery port in Xingzi and in shallow main and side channels south from the hill with the 'park with wind turbines' (location described in introduction part). These animals, however, avoided busy areas of the sand dredging machinery.

Poyang Lake, sand dredging, 2011:
Large dredging vessels are navigating through the narrow water channel in dry season. Poyang Lake, sand dredging, 2011:
Dredging of sand and clay is important to keep up with the high growth of construction industry. This lake use has, however, also an impact on shore habitat of aquatic biota.

Poyang Lake, sand dredging, 2011:
Loading of vessels by sand from dredging vessels - the many vessels are narrowing further the already slender channel in dry season.Poyang Lake, sand dredging, 2011:
Sand dredging in the lake to maintain the navigation channel.

Finally, even if this aspect is already mentioned before, it is worth highlighting again that lake Poyang serves as an important waterway. The north of the lake connects with the Yangtze River. The many material and goods seen on large cargo vessels ranged from oil, sand and clay to straw as illustrated by a few photos below.

Poyang Lake as important waterway, 2011:
Small boats and very many large vessels are typically met on the journey through the northern part of the lake that connects to the Yangtze River.Poyang Lake as important waterway, 2011:
Shipment of goods.

Poyang Lake as important waterway, 2011:
Shipment of straw. Poyang Lake as important waterway, 2011:
Shipment of fuel.