2. Wang, H. Z. & C. Erséus, 2001. Marine Phallodrilinae (Oligochaeta, Tubificidae) of Hainan Island in southern China. Hydrobiologia, 462: 199-204. [Wang01aHydrobiologia.pdf]

Abstract:

Six species of Phallodrilinae are reported from Hainan Island in southern China. The mesopsammic Aktedrilus yiboi sp. nov. is new to science. It is characterized by a combination of (1) small, straight, conical, strongly cuticularized penis sheaths, (2) posterior prostate glands being associated with the most ectal parts of the atria, and (3) small spermathecal ampulla. Bathydrilus ampliductus Erséus, 1997 is recorded for the first time since it was originally described from Australia’s Northern Territory.

Key words: Phallodrilinae, marine oligochaetes, taxonomy, new species, Hainan.

 3. Wang, H. Z. & Y. L. Liang, 2001. A preliminary study of oligochaetes in Poyang Lake, the largest freshwater lake of China, and its vicinity, with description of a new species of Limnodrilus. Hydrobiologia, 463: 29-38. (SCI) [Wang01bHydrobiologia.pdf]

Abstract:

The oligochaete fauna of the largest freshwater lake of China, Poyang Lake, has never been investigated before. On the basis of a preliminary survey in the lake and its vicinity in 1997-1999, 25 species belonging to 20 genera and 5 families are recorded. Among them, one genus, Cernosvitoviella (Enchytraeidae), and two species, Bratislavia unidentata (Naididae), Potamothrix bedoti (Tubificidae), are recorded from China for the first time. Another tubificid, Limnodrilus paramblysetus sp. nov., is new to science. It is similar to L. amblysetus Brinkhurst et al., 1990 in chaetal shape but differs in having short hooded penis sheaths.

Key words: Tubificidae, Naididae, freshwater oligochaetes, taxonomy, new species, Poyang Lake

4. Gibson, R. & H. Z. Wang, 2002. A new genus and species of freshwater Monostiliferous hoplonemertean (Nemertea, Enopla) from the People’s Republic of China. Hydrobiologia 489:185-196.〔GibsonWang02Hydrobiologia.pdf〕

Abstract:

A new genus and species of freshwater monostiliferous hoplonmertean, Limnemertes poyangensis gen. et sp. nov., from Poyang Lake, People's Repulic of China, is described and illustrated. the taxon is compared and contrasted with previously described freshwater hoplonemerteans. This is the fourth species of freshwater nemertean to be described from China and the first record from Poyang Lake. 

Key words: freshwater nemertean,  hoplonemertea, People's Repulic of China, Poyang Lake, Limnemertes poyangensis gen. et sp. nov.

5. Wang, H. Z. & C. Erséus, 2003. Marine species of Ainudrilus and Heterodrilus (Oligochaeta: Tubificidae: Rhyacodrilinae) from Hainan Island in southern China. New Zealand Journal of Marine and Freshwater Research, 37: 205-217.[Wang03 NewZealJMarFresh.pdf]

Abstract:

 Six species of Rhyacodrilinae (Oligochaeta: Tubificidae) are reported from intertidal and shallow-water subtidal habitats around Hainan Island in southern China. Four species are new to science: Ainudrilus pauciseta n. sp., Heterodrilus chenianus n. sp., Heterodrilus nudus n. sp., and Heterodrilus uniformis n. sp. Japanese material of Ainudrilus lutulentus (Erséus, 1984) is also briefly described. Hitherto, 27 species belonging to Tubificidae have been recorded from Hainan.

Key words:  Ainudrilus; Heterodrilus; Tubificidae; marine oligochaetes; taxonomy; new species; faunal diversity; southern China; Japan

6. Wang, H. Z. & C. Erséus, 2004. New species of Doliodrilus and other Limnodriloidinae (Oligochaeta, Tubificidae) from Hainan and other parts of the north-west Pacific Ocean. Journal of Natural History, 38: 269-299.[Wang04JNatHist.pdf]

Abstract:

Thirteen species of Limnodriloidinae (Tubificidae) are recorded from marine and brackish-water habitats of Hainan Island, southern China, including eleven species of Doliodrilus and two species belonging to Limnodriloides. Eight species are new to science: D. bisaccus sp. n. (types from Japan), D. longidentatus sp. n. (types from Hong Kong), D. ciliatus sp. n., D. adiacens sp. n., D. fibrisaccus sp. n. (also from Fiji), D. brachyductus sp. n., D. bidolium sp. n., and D. chinensis sp. n. In addition, material of D. puertoricensis Erséus and Milligan, 1988, from New Caledonia, is briefly described. This study shows that Doliodrilus is unexpectedly species-rich in Asian seas, in particular, around Hainan. Including an unnamed species from this island, the known members of this genus increase from three to twelve.

Key words: Doliodrilus, Limnodriloidinae, Oligochaeta, taxonomy, new species, southern China, Japan, Fiji, New Caledonia.

7. Cui, Y. D. & H. Z. Wang. 2005. Potamothrix scleropenis sp. nov. (Oligochaeta: Tubificidae) from the Fuxian Lake, the deepest lake in southwest China. Zoological Science, 22: 1353-1357. 〔CuiWang05ZoolSci.pdf〕

Abstract:

Potamothrix scleropenis sp. nov. (Tubificidae: Tubificinae) is described from the profundal zone (74 m) of Fuxian Lake, the deepest lake (up to 155 m) on the Yunnan-Guizhou Plateau in China. The new species is assigned to Potamothrix because of its short vasa deferentia and its tubular atria without ejaculatory ducts and prostate glands. It differs from congeners by its cuticularized penis sheaths; bifurcated, strongly curved spermathecal chaetae; bifurcated lower prongs of bifids; and feathered hairs. P. scleropenis appears closely related to P. cekanovskajae Finogenova, 1972 and P. tudoranceai Šporka, 1994, since all the three species have homogeneous atria without prostate glands.

Key words: Potamothrix, profundal Tubificinae, new species, Fuxian Lake, Yunnan Province

8.Cui, Y. D. & H. Z. Wang. 2009. Three new species of Tubificidae, Oligochaeta, from two plateau lakes in Southwest China. Zootaxa, 2143: 45-54.[CuiWang09Zootaxa]

Abstract:

Three new species of Tubificinae (Naididae, Oligochaeta), Varichaetadrilus vestibulatus n. sp., Aulodrilus apeniatus n. sp., and Ilyodrilus mesoprostatus n. sp., are reported from Fuxian Lake and Xingyun Lake of Yunnan Province, Southwest China. V. vestibulatus differs from its allies by possessing modified spermathecal chaetae and thinner cylindrical penial sheaths. A. apeniatus is unique in the genus by having no penis. I. mesoprostatus is distinguishable from congeners by its prostate glands joining middle portion of atria and having concave, cone-shaped cuticular penial sheaths. Twenty-eight species of freshwater oligochaetes have hitherto been recorded from Yunnan Province, including five endemic species from three plateau lakes.

Key words: Varichaetadrilus, Aulodrilus, Ilyodrilus, Tubificinae, taxonomy, new species, Fuxian Lake, Xingyun Lake,
Yunnan Province

1.  许巧情，王洪铸，张世萍，2003。河蟹过度放养对湖泊底栖动物群落的影响。水生生物学报，27 (1)：41-46。[XuWang03ActaHydrobiolSin.pdf]

摘要：本文通过河蟹养殖的代表湖泊黄湖与参照水体即黄湖围栏外、天然捕捞湖泊龙感湖以及鱼类放养湖泊牛山湖的比较，探讨河蟹过度放养对湖泊底栖动物群落结构和功能的影响。结果表明，河蟹影响底栖动物群落的途径有两条，一是直接摄食，二是破坏沉水植物的间接作用。在蟹苗放养强度约1 kg×hm-2的条件下，底栖动物的种类多样性明显下降，密度和生产量减少60%以上，其中对小型螺类的影响尤甚。作者认为目前最适的养殖模式应是河蟹与非草食性鱼类的轮作经营。

关键词：河蟹放养；底栖动物；现存量；功能摄食类群；生产量；蟹鱼轮作

2. Wang, H. Z., H. J. Wang, X. M. Liang, L. Y. Ni, X. Q. Liu & Y. D. Cui. 2005. Empirical modelling of submersed macrophytes in Yangtze lakes. Ecological Modelling, 188: 483-491. [Wang05EcolModel.pdf]

Abstract:

Submersed macrophytes in Yangtze lakes have experienced large-scale declines due to the increasing human activities during past decades. To seek the key factor that affects their growth, monthly investigations of submersed macrophytes were conducted in 20 regions of 4 Yangtze lakes during December, 2001-March, 2003. Analyses based on annual values show that the ratio of Secchi depth to mean depth is the key factor (50% of macrophyte biomass variability among these lakes is statistically explained). Further analyses also demonstrate that the months from March to June are not only the actively growing season for most macrophytes, but the key time the factor acts. Five key-time models yielding higher predictive power (r2 reaches 0.75, 0.76, 0.77, 0.69 and 0.81) are generated. A comparison between key-time models and traditional synchronic ones indicates that key-time models have higher predictive power. Analyses of transparency thresholds during macrophyte growing season and the limitations of the models are presented. The models and other results may benefit the work concerning submersed macrophyte recovery in Yangtze lakes.

Key words: Key-time models; Submersed macrophytes; Yangtze shallow lakes; Biomass; Transparency thresholds

3. Wang, H. Z., H. J. Wang, X. M. Liang & Y. D. Cui. 2006. Stocking models of Chinese mitten crab (Eriocheir japonica sinensis) in Yangtze lakes. Aquaculture, 255: 456-465.[Wang06Aquaculture.pdf]

Abstract:

The farming of Chinese mitten crab, a quality aquatic product in China and neighbouring Asian countries, has been developing rapidly in China since last decade. It reached a total yield of 3.4×105 tonnes in 2002. Due to the successive over-stocking year after year, many lakes in the mid-lower Yangtze Basin, the main farming area, are under deterioration, leading to a reduction of crab yield and quality, and subsequently, a loss of farming profits. Aiming at a normal development of crab culture and the sustainable use of lakes, an annual investigation dealing with lake environmental factors in relation to stocked crab populations was carried out at 20 farms in 4 lakes. The results show that the submersed macrophyte biomass (BMac) is the key factor affecting annual crab yield (CY). Using the ratio of Secchi depth to mean depth (ZSD/ZM), an easily measured parameter closely correlated to BMac, as driving variable, 10 regression models of maximal crab yields were generated (r2 ranging 0.49-0.81). Based on the theory of MSY (Maximum Sustainable Yield), in combination with body-weight (BW) and recapture rate (RR) of adult crabs, a general optimal stocking model was eventually formulated. All models are simple and easy to operate. Comments on their applications and prospects are given in brief.

Key words: Yangtze lakes; Chinese mitten crab culture; Maximal yield models; Optimal-stocking model

4. Liu, X. Q., H. Z. Wang & X. M. Liang, 2006. Food web of macroinvertebrate community in a Yangtze shallow lake: trophic basis and pathway. Hydrobiologia, 571: 283-295.[LiuWang06Hydrobiologia.pdf]

Abstract:

No detailed food web research on macroinvertebrate community of lacustrine ecosystem was reported in China. The present study is the first attempt on the subject in Lake Biandantang, a macrophytic lake in Hubei Province. Food webs of the macroinvertebrate community were compiled bimonthly from March, 2002 to March, 2003. Dietary information was obtained from gut analysis. Linkage strength was quantified by combining estimates of energy flow (secondary production) with data of gut analysis. The macroinvertebrate community of Lake Biandantang was based heavily on detritus. Quantitative food webs showed the total ingestion ranged from 6930 to 36340 mg dry mass m-2 bimonthly. The ingestion of macroinvertebrate community was higher in the months with optimum temperature than that in other periods with higher or lower temperature. Through comparison, many patterns in benthic food web of Lake Biandantang are consistent with other detritus-based webs, such as stream webs, but different greatly from those based on autochthonous primary production (e.g. pelagic systems). It suggests that the trophic basis of the web is essential in shaping food web structure.

Key words: Yangtze shallow lake, macroinvertebrates, trophic basis, food web quantification

5. Wang, H. J., B. Z. Pan, X. M. Liang & H. Z. Wang. 2006. Gastropods on submerged macrophytes in Yangtze Lakes: community characteristics and empirical modelling. International Review Hydrobiology, 91(6): 521-538.[WangWang06InternatRevHydrobiol.pdf]

Abstract:

Key words: epiphytic gastropods, Yangtze shallow lakes, community structure, empirical models, preference analyses.

6. 姜苹红，梁小民，陈芳，周易勇，王洪铸。2006。月湖底栖动物的空间格局及其对水草可恢复区的指示。长江流域资源与环境，4：439-445.[JiangWang06ResEnvYangtzeBasin.pdf]

摘要：底质适宜是富营养湖泊恢复沉水植物(水草)的重要前提。由于大型底栖动物可综合指示底质的污染程度，我们于2002-2003年在武汉月湖开展了底栖动物水平分布对水草可恢复区指示作用的研究。首先通过月湖底栖动物与环境的相关分析选择颤蚓科寡毛类作为底质营养状况的指示类群，然后利用同类湖泊群颤蚓与水草数据分析阈值，初步确定颤蚓密度 小于或等于100 ind/m²的底质适合水草生长，最后绘制月湖颤蚓分布的水平等值线，显示水草恢复的合适区域。本文构建了应用底栖动物空间格局指示水草恢复区的技术原理框架，而国内外尚未见类似的报道.

关键词：大型底栖动物；颤蚓密度等值线；沉水植物恢复阈值；富营养浅水湖泊；武汉月湖

7. Liu, X. Q. and Wang, H. Z. 2007. Food composition and dietary overlap of macroinvertebrates in a shallow eutrophic lake in China: spatial and temporal variations. Fundamental and Applied Limnology, 168: 71-82. 〔LiuWang07FundApplLimno.pdf〕

Abstract:

The present study was conducted in Lake Donghu, a suburban eutrophic lake arising from the middle reaches of the Yangtze River, China. Food composition of 32 taxa of zoobenthos was analyzed from 1251 gut samples. Macroinvertebrate primary consumers ingested mainly detritus, sand grains and diatoms. The predators primarily preyed on rotifers, crustaceans, oligochaetes and chironomid larvae. The dietary overlap was relatively high among collector taxa but low among other macroinvertebrates. Food composition and dietary overlap of macroinvertebrates changed considerably, both spatially and temporally. Food web structure differed between inshore and offshore regions of Lake Donghu. The inshore web was relatively complex and dynamic whereas the offshore web was simple and stable. Taxon-specific changes of diet seem to have little effect on the benthic food web structure in offshore waters of a eutrophic lake.

Key words: food composition, dietary overlap, macroinvertebrates, eutrophic lake

8. Wang, H. Z., Xu, Q. Q., Cui, Y. D. and Liang, Y. L. 2007. Macrozoobenthic community of Poyang Lake, the largest freshwater lake of China, in the Yangtze floodplain. Limnology, 8: 65-71.[Wang07Limnology.pdf]

Abstract:

Poyang Lake (Poyang Hu) is located at the junction of middle and lower reaches of the Yangtze (Changjiang) River, covering an area of 3283 km2. As one of the few lakes that are still freely connected with the river, it plays an important role in the maintenance of the unique biota of the Yangtze floodplain ecosystem. To promote the conservation of Poyang Lake, an investigation of macrobenthos in the lake itself and adjoining Yangtze mainstream was conducted in 1997-1999. Altogether 58 benthic taxa, including 22 annelids, 8 molluscs, 26 arthropods, and 2 miscellaneous animals, were identified from quantitative samples. The benthic fauna shows a high diversity and a marine affinity. The standing crops of benthos in the lake were much higher than those in the river, being 659 individuals/m2 and 187.3 g/m2 (wet mass) in the main lake, 549 individuals/m2 and 116.6 g/m2 in the lake outlet, but only 129 individuals/m2 and 0.4 g/m2 in the latter. The dominant group in the lake was Mollusca, comprising 63.4% of the total in density and 99.5% in biomass. An analysis of functional feeding structure indicated that collector-filterers and scrapers were predominant in the lake, up to 42.2 %, 24.7% in density and 70.2%, 29.2% in biomass, while shredders and collector-gatherers were relatively common in the river. The present study was restricted to the northern outlet and the northeast part of Poyang Lake. A scrutiny is required for the remaining area.

Key words: Macrozoobenthos, River-connected lake, Community structure, Yangtze floodplain

9.  Cui, Y. D., Liu, X. Q. and Wang, H. Z. 2008. Macrozoobenthic community of Fuxian Lake, the deepest lake of southwest China. Limnologica, 38: 116-125. 〔CuiWang08Limno.pdf〕

Abstract：

Located in the Yunnan-Guizhou Plateau in southwest China, Fuxian Lake covers an area of 211 km2, with maximum depth of 155 m. It is known to have a unique fauna, from which 14 endemic species have been described. Purposing to apprehend the situation of zoobenthic community in the lake, the present study was conducted from August 2002 to August 2003. Altogether 62 benthic taxa including 22 oligochaetes, 21 molluscs and 18 insects were identified, with predominant taxa belonging to Potamothrix, Procladius and Paraprososthenia. The standing crops of benthos were much higher in littoral (824 ind/m² in density, 3.72 g/m² in biomass) than those in profundal (23 ind/m² in density, 0.10 g/m² in biomass). Seasonal fluctuation occurred, showing richer species in summer and higher standing crops in spring and summer. Analyses of functional feeding groups indicated that collector-gatherers and scrapers were predominant in entire lake. Stepwise multiple regression analysis demonstrated that the water depth is the key factor affecting macrozoobenthos.  

Key words: Macrozoobenthos, Taxonomic composition, Standing crop, Functional feeding group, Fuxian Lake

10. Wang, H. J., Liang, X. M., Jiang, P. H., Wang, J., Wu, S. K. and Wang, H. Z. 2008. TN:TP ratio and planktivorous fish do not affect nutrient-chlorophyll relationships in shallow lakes. Freshwater Biology, 53: 935-944. [WangWang08FreshwatBiol.pdf]

Summary

1. In previous work, phytoplankton regulation in freshwater lakes has been associated with many factors. Among these, the ratio of total nitrogen to total phosphorus (TN: TP) has been widely proposed as an index to identify whether phytoplankton are nitrogen-limited or phosphorus-limited. From another point of view, it has been suggested that planktivorous fish can be used to control phytoplankton.

2. Large-scale investigations of phytoplankton biomass (measured as chlorophyll a, Chl a) were carried out in 45 mid-lower Yangtze shallow lakes to test hypotheses concerning nutrient limitation (assessed with TN: TP ratios) and phytoplankton control by planktivorous fish.

3. Regression analyses indicated that TP was the primary regulating factor and TN the second regulating factor for both annual and summer phytoplankton Chl a. In separate nutrient-Chl a regression analyses for lakes of different TN: TP ratios, TP was also superior to TN in predicting Chl a at all particular TN: TP ranges and over the entire TN: TP spectrum. Further analyses found that Chl a: TP was not influenced by TN: TP, while Chl a: TN was positively and highly correlated to TN: TP. 

4. Based on these results, and others in the literature, we argue that the TN: TP ratio is inappropriate as an index to identify limiting nutrients. It is almost impossible to specify a “cut-off” TN: TP ratio to identify a limiting nutrient for a multi-species community because optimal N: P ratios vary greatly among phytoplankton species.

5. Lakes with yields of planktivorous fish (silver and bighead carp, the species native to China) greater than 100 kg ha-1 had significantly higher Chl a and lower Secchi depth than those with yields less than 100 kg ha-1. TP-Chl a and TP-Secchi depth relationships are not significantly different between lakes with yields greater than or less than 100 kg ha-1. These results indicate that the fish failed to decrease Chl a yield or enhance ZSD. Therefore, silver carp and bighead carp are not recommended as a biotic agent for phytoplankton control in lake management if the goal is to control the entire phytoplankton and to enhance water quality.

 Keyword: phytoplankton, chlorophyll a, total phosphorus, TN: TP ratio, planktivorous fish

11. 茹辉军、刘学勤、黄向荣、宁应之、王洪铸。2008。大型通江湖泊洞庭湖的鱼类物种多样性及其时空变化。湖泊科学，20：96-102。[RuWang08JLakeSci.pdf]

摘要：为了解通江湖泊鱼类物种多样性现状，于2004年3月－2004年12月和2005年5月对洞庭湖城陵矶、岳阳和沅江三个区域的鱼类进行逐月调查。共鉴定鱼类69种，隶属6目14科44属，其中59.4％为鲤科鱼类。以种类数和多样性指数分析了群落多样性特征，结果表明洞庭湖鱼类种类多样性较高，且时空变化较大。一般地，湖区与长江干流的距离越近，种类数达到峰值的时间就越早；鱼类多样性在春夏季高于秋冬季，在南洞庭湖高于其它两个区域。以优势度>5000为标准，全湖有17种优势种，其中80.0％为湖泊定居性鱼类。在生态类群方面，湖泊定居性鱼类种类最多，占总种类数的74.0％；江湖洄游性鱼类最少，占13.0％。对比分析显示，由于生境丧失、天然苗种资源衰退和过度捕捞等原因，洞庭湖鱼类多样性较20世纪70年代明显下降，洄游鱼类种类数减少；通江湖泊鱼类多样性明显高于阻隔湖泊，表明江湖阻隔造成鱼类多样性下降，因此，加强江湖连通是保护鱼类多样性的有效手段。

关键词: 洞庭湖; 鱼类; 种类组成; 物种多样性; 通江湖泊

12. Liu, X. Q. & H. Z. Wang. 2008. Food web of benthic macroinvertebrates in a large Yangtze River-connected lake: the role of flood disturbance. Fundamental and Applied Limnology. 171/4: 297-309.[Liuwang08FundApplLimno.pdf]

Abstract:
This study was conducted in Lake Dongtinghu, a large river-connected lake on the Yangtze River floodplain, China. Our goal was to determine trophic relationships among benthic macroinvertebrates, as well as the effects of flood disturbance on the benthic food web of a river-connected lake. Macroinvertebrates in the lake fed mainly on detritus and plankton (both zooplankton and phytoplankton). Food web structure in Lake Dongtinghu was characterized by molluscs as the dominant group, low connectance, high level of omnivory, based on detritus and primary production, and most ingestion concentrating on a few links. Our analyses showed that flood disturbance is an important factor affecting the benthic food web in Lake Dongtinghu. The numbers of species and functional feeding groups (FFGs), and the density and biomass of macroinvertebrates decreased significantly during flooding. Connectance was higher during the flood season than in other seasons, indicating that floods have a strong effect on connectance in this Yangtze River-connected lake. Flood effects on the benthic web were also evident in the decrease of niche overlaps within and among FFGs. Our results provide useful information regarding biodiversity conservation on the Yangtze floodplain. Reconstructing and maintaining natural and regular flow regimes between Yangtze lakes and the river is essential for restoration of macroinvertebrates on the floodplain.

Keywords: macroinvertebrates, food web, flood disturbance, floodplain, Lake Dongtinghu

13. Pan, B.Z., H.J. Wang, X.M. Liang & H.Z. Wang. 2009. Phytoplankton chlorophyll a in the Yangtze-connected lakes: present state, influencing factors and empirical relationships. Fresenius Environmental Bulletin, 18 (10): 1894-1900.[PanWang09FreEnvironBull]

Abstract:

To determine the environmental factors influencing phytoplankton chlorophyll a (Chl a), field investigations were conducted in three river-connected lakes (Dongting Lake, Poyang Lake and Shijiu Lake) of the Yangtze flood-plain in 2004. Results showed that the average Chl a concentration in these lakes ranged from 2.98 to 3.65 mg m-3. The major factors influencing Chl a in lentic and lotic regions were total phosphorus (TP) and water velocity (U), respectively. Multiple relationships including total nitrogen (log10TN) and water depth (log10Z) were established. Further analyses found that the absolute Chl a and slope of log10Chl a＝f (log10TP) in the river-connected lakes were obviously lower than those in the river-isolated lakes. This suggests the river-lake connectivity can significantly modify relationship between TP and chlorophyll a concentration.

Keywords: chlorophyll a, water velocity, total phosphorus, river-connected lakes.

14. Wang, H. J., H. Z. Wang. 2009. Mitigation of lake eutrophication: loosen nitrogen control and focus on phosphorus abatement. Progress in Natural Science, 19 (11): 19 (11): 1145-1451.[WangWang09ProNatSciE]

Abstract:

Traditionally, nitrogen control is generally considered an important component of reducing lake eutrophication and cyanobacteria blooms. However, this viewpoint is refuted recently by researchers in China and North America. In the present paper, the traditional viewpoint of nitrogen control is pointed out to lack a scientific basis: the N/P hypothesis is just a subjective assumption; bottle bioassay experiments fail to simulate the natural process of nitrogen fixation. Our multi-year comparative research in more than 40 Yangtze lakes indicates that phosphorus is the key factor determining phytoplankton growth regardless of nitrogen concentrations and that total phytoplankton biomass is determined by total phosphorus and not by total nitrogen concentrations. These results imply that, in the field, nitrogen control will not decrease phytoplankton biomass. This finding is supported by a long-term whole-lake experiment from North America. These outcomes can be generalized in terms that a reduction in nitrogen loading may not decrease the biomass of total phytoplankton as it can stimulate blooms of nitrogen-fixing cyanobacteria. To mitigate eutrophication, it is not nitrogen but phosphorus that should be reduced, unless nitrogen concentrations are too high to induce direct toxic impacts on human beings or other organisms. Finally, details are provided on how to reduce controls on nitrogen and how to mitigate eutrophication.

Key words: Lake eutrophication; Cyanobacteria blooms; Lake restoration

 湖泊河蟹持续产量最大化放养技术

河蟹即中华绒螯蟹[Eriocheir japonica sinensis (H. Milne-Edwards)]，肉味鲜美，营养丰富，深受国内外消费者欢迎。近年来，河蟹的市场需求量日益增长，养殖前景极为广阔，养殖面积也越来越大，河蟹的湖泊养殖已逐步发展成为我国的一项支柱水产业。但是由于过度放养导致资源枯竭、水质恶化，湖泊河蟹养殖业的经济效益普遍滑坡。因此，迫切需要研究湖泊河蟹最适放养量技术从而实现最大持续产量。

本成果应用渔业生态学和预测湖沼学原理和方法，系统分析河蟹放养的生态学效应，确定沉水植物生物量为河蟹产量的限制因子，进而在建立沉水植物模型的基础上确定放养时期的透明度/水深为驱动变量，建立了最大产量模型并开展实际验证，最后根据最大持续产量理论建立最适放量模型。建模主要依据2001.12-2003.3在梁子湖群等20个湖区逐月的调查结果，实际验证于2003-2005年在长江中游的27湖区进行。

本成果的主要内容如下：

1)系统分析河蟹放养的生态学效应

通过对不同程度河蟹放养强度湖泊的系统比较发现，河蟹的过度放养导致沉水植物衰退甚至消失，继而浮叶植物泛滥，导致水质恶化、动物食料匮乏。在蟹苗放养强度约1 kg×hm^-2的条件下，湖水总氮和总磷约增加50%，叶绿素含量约增加一倍；底栖动物的种类多样性明显下降，密度和生产量减少60%以上，对小型螺类的影响尤甚。

2)确定沉水植物生物量为河蟹产量的关键因子

通过河蟹产量与理化因子、叶绿素、浮游生物、底栖动物和沉水植物等因子的相关分析和逐步回归分析发现，沉水植物生物量是影响河蟹产量的关键因子。沉水植物及其附着螺类等为河蟹提供了丰富的食物；可为河蟹提供了良好的栖息场所；可改善水质，提高河蟹品质。

3)建立沉水植物等资源的预测模型

由于沉水植物生物量难以测准，不宜作为河蟹模型的驱动变量。因此，进一步建立了沉水植物模型，以确定简单且可准确测定的驱动变量。分析表明透明度-水深之比（Z_SD/Z_M）是影响沉水植物生物量（B_Mac, g/m²）的关键因子，且3-6月为关键作用期，据此建模：B_Mac =-3931+7072.9 Z_SD/Z_M  r²=0.81 p<0.001 n=18。同时，还建立了河蟹主要食料资源底栖动物和附草螺类的预测模型。

 4)建立河蟹最大产量模型并实际验证

以投放季节（12月-5月）的Z_SD/Z_M作为驱动变量，建立系列河蟹产量模型如下：

河蟹最大产量模型 (n=18, p<0.001)

表中：CY_Max为河蟹最大产量(kg/ha)，Z_SD/Z_M为透明度－水深之比。

 由于所有湖泊的蟹苗放养量足够，上述模型为最大产量模型。进一步用27个草型湖泊的独立数据验证发现，单月模型的预测值与实测值的r²达49％，准确率达70%，表明模型有较强的预测能力。

 5)建立河蟹最适放养量模型

要实现河蟹的最大持续产量，必须使食物资源达到最大持续产量。根据最大持续产量理论，当生物的现存量为环境容量的1/2时，其瞬时增长率最大，可实现最大持续产量。由于沉水植物的非呼吸损失相对较小，它们的年净生产量约等于年最大生物量。因此，从理论上认为利用沉水植物群落资源的50%可实现河蟹的最大可持续生产量。上述模型中河蟹当年的最大产量是在对沉水植物群落资源几乎完全利用之后获得的，因此可以认为要实现河蟹的最大可持续产量，其年产量只能达到当年最大产量的50%。相应地，最适放养密度（SR_Opt, ind/ha）可通过如下方程求得：

SR_Opt=                                                                               (11)

式中，CY_Max为当年的河蟹最大产量，代入最大产量模型(1)-(10)即可。CY前乘以1000是为了统一单位。BW和RR分别为成蟹规格和回捕率。

本成果的创新点为：本成果研制的放养模型简单实用，而过去关于河蟹养殖容量仅有水族箱研究的报道，难以推广到大水面。与国内外关于养殖容量的模型法研究相比，本成果有两个创新点：1)模型所用驱动变量简单易测，生产者容易掌握，而其他模型的驱动变量为生物参数或化学参数，较难测定；2)模型采用放养时期的参数为驱动变量，可及时准确地服务于放养生产，而过去的模型均采用生长期或捕捞期的参数为驱动变量，对估算当年放养量的作用有限。

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