Forty questions of importance to the policy and practice of native oyster reef restoration in Europe
Ermgassen, Philine S.E. zu; Bonačić, Kruno ; Boudry, Pierre ; Bromley, Cass A. ; Cameron, Tom C. ; Colsoul, Bérenger ; Coolen, Joop W.P. ; Frankić, Anamarija ; Hancock, Boze ; Have, Tom M. van der; Holbrook, Zoë ; Kamermans, Pauline ; Laugen, Ane T. ; Nevejan, Nancy ; Pogoda, Bernadette ; Pouvreau, Stéphane ; Preston, Joanne ; Ranger, Christopher J. ; Sanderson, William G. ; Sas, Hein ; Strand, Åsa ; Sutherland, William J. - \ 2020
Aquatic conservation: marine and freshwater ecosystems 30 (2020)11. - ISSN 1052-7613 - p. 2038 - 2049.
alien species - estuary - fishing - invertebrates - pollution - restoration - subtidal
Oyster reefs are among the most threatened marine habitats globally. In Europe, oyster reefs have been extirpated from most locations within their historical range. Active restoration of the native oyster (Ostrea edulis) in Europe has grown substantially in recent years. In sharing experiences between oyster restoration projects in Europe at the Native Oyster Restoration Alliance conference, NORA2, in Edinburgh in May 2019, it became apparent that a number of similar barriers are experienced. This study identified the top 40 questions, which, if answered, would have the greatest influence on the policy and practice of oyster restoration in Europe. Initially 71 people were consulted across 28 institutions and 11 European countries to generate 194 questions. An established process of one round of pre-workshop voting followed by a one-day online workshop and two post-workshop rounds of voting resulted in the final 40 questions. Questions were broadly grouped into the following 10 themes: baselines, site selection, restoration methods, quantifying benefits, disease management, biosecurity, genetic diversity and population differentiation, policy and management, novel technologies, and current and future threats. We anticipate that this list will provide a starting point for developing collaborative projects across the NORA network, as well as assisting policy makers and funders with identifying key areas that need to be addressed in order to overcome existing barriers to scaling up oyster restoration in Europe.
Optimization of off-bottom spat collectors for restoration and production of the European flat oyster (Ostrea edulis) in Dutch coastal waters
Brink, Anneke M. van den; Maathuis, Margot A.M. ; Kamermans, Pauline - \ 2020
Aquatic conservation: marine and freshwater ecosystems 30 (2020)11. - ISSN 1052-7613 - p. 2087 - 2100.
aquaculture - coastal - estuary - invertebrates - new techniques - Ostrea edulis - reproduction, restoration
Efficient spat collection is essential to both the successful restoration and cultivation of the European flat oyster (Ostrea edulis). The results of four different experiments investigating larval abundance, and the use of seven different types of suspended spat collectors in seven locations in the SW Netherlands were compared. These different types included Chinese hats, Vexar mesh, PVC tubes, and four types of bivalve shells. Larval abundance, and timing of peaks in abundance for both O. edulis and the non-indigenous Pacific oyster (Crassostrea gigas) varied between locations and years. The most successful spat collectors were sacks of bivalve shells. In general, most spat were observed on collectors deployed 1–2 weeks after the peak in larval abundance was detected. Fouling was heavy and may have prevented larval settlement on collectors deployed too early. Suspended sacks of bivalve shells show great promise as O. edulis spat collectors intended for reef restoration purposes but may need further development for cultivation application.
Manila River Mouths Act as Temporary Sinks for Macroplastic Pollution
Emmerik, Tim van; Klaveren, Justin van; Meijer, Lourens J.J. ; Krooshof, Joost W. ; Palmos, Dixie A.A. ; Tanchuling, Maria Antonia - \ 2020
Frontiers in Marine Science 7 (2020). - ISSN 2296-7745
estuary - floating debris - hydrology - marine litter - Philippines - plastic - river plastic
The Philippines is suggested to be one of the world's main contributors to global marine plastic pollution. Several rivers in the Manila metropolitan area are assumed to be main pathways of land-based plastic waste into the ocean. However, these model estimates remain uncertain due to a lack of field data. The main goal of this study was therefore to collect field data on floating macroplastic flux and polymer category in three of Manila's main rivers: the Meycauayan, Tullahan and Pasig. We measured plastic flux, item polymer category, and flow velocity at two locations per river during an 11-day period. Each river was measured close to the river mouth, and several kilometer upstream. The results showed no significant difference between the plastic flux in upstream and downstream flow direction at the three river mouths. The Meycauayan and Pasig rivers did have significantly higher plastic flux at the river mouth compared to the upstream location. The observations suggest accumulation of macroplastics in the river mouths during periods of low freshwater discharge. In this case, instantaneous plastic flux is mainly determined by the tidal dynamics. It is hypothesized that plastics are temporarily retained in estuaries, and may be flushed out during neap tide or increased river discharge. Due to the retention capacity of the estuaries, net plastic export into the ocean could not be estimated. Future research is needed to further investigate the role of tidal dynamics on the transport and net export of riverine macroplastics.
Future Change to Tide-Influenced Deltas
Nienhuis, Jaap H. ; Hoitink, A.J.F. ; Törnqvist, Torbjörn E. - \ 2018
Geophysical Research Letters 45 (2018)8. - ISSN 0094-8276 - p. 3499 - 3507.
channel width - estuary - river delta - tides
Tides tend to widen deltaic channels and shape delta morphology. Here we present a predictive approach to assess a priori the effect of fluvial discharge and tides on deltaic channels. We show that downstream channel widening can be quantified by the ratio of the tide-driven discharge and the fluvial discharge, along with a second metric representing flow velocities. A test of our new theory on a selection of 72 deltas globally shows good correspondence to a wide range of environments, including wave-dominated deltas, river-dominated deltas, and alluvial estuaries. By quantitatively relating tides and fluvial discharge to delta morphology, we offer a first-order prediction of deltaic change that may be expected from altered delta hydrology. For example, we expect that reduced fluvial discharge in response to dam construction will lead to increased tidal intrusion followed by enhanced tide-driven sediment import into deltas, with implications for navigation and other human needs.
Benthic primary producers are key to sustain the Wadden Sea food web : stable carbon isotope analysis at landscape scale
Christianen, M.J.A. ; Middelburg, J.J. ; Holthuijsen, S.J. ; Jouta, J. ; Compton, T.J. ; Heide, T. van der; Piersma, T. ; Sinninghe Damsté, J.S. ; Veer, H.W. van der; Schouten, S. ; Olff, H. - \ 2017
Ecology 98 (2017)6. - ISSN 0012-9658 - p. 1498 - 1512.
carbon subsidy - coastal food web - Dutch Wadden Sea - estuary - macrobenthos - stable carbon isotopes - tidal wetland ecosystem
Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the landscape scale is often unclear, as many studies lack good taxonomic and spatial resolution across large areas. Here, using stable carbon isotopes, we report on the primary carbon sources for consumers and their spatial variability across one of the world's largest intertidal ecosystems (Dutch Wadden Sea; 1460 km2 intertidal surface area), at an exceptionally high taxonomic (178 species) and spatial resolution (9,165 samples from 839 locations). The absence of overlap in δ13C values between consumers and terrestrial organic matter suggests that benthic and pelagic producers dominate carbon input into this food web. In combination with the consistent enrichment of benthic primary producers (δ13C −16.3‰) relative to pelagic primary producers (δ13C −18.8) across the landscape, this allowed the use of a two-food-source isotope-mixing model. This spatially resolved modelling revealed that benthic primary producers (microphytobenthos) are the most important energy source for the majority of consumers at higher trophic levels (worms, molluscs, crustaceans, fish, and birds), and thus to the whole food web. In addition, we found large spatial heterogeneity in the δ13C values of benthic primary producers (δ13C −19.2 to −11.5‰) and primary consumers (δ13C −25.5 to −9.9‰), emphasizing the need for spatially explicit sampling of benthic and pelagic primary producers in coastal ecosystems. Our findings have important implications for our understanding of the functioning of ecological networks and for the management of coastal ecosystems.
The ecosystem engineer Crassostrea gigas affects tidal flat morphology beyond the boundary of their reef structures
Walles, B. ; Salvador de Paiva, J. ; Prooijen, B. van; Ysebaert, T. ; Smaal, A.C. - \ 2015
Estuaries and coasts 38 (2015)3. - ISSN 1559-2723 - p. 941 - 950.
wadden sea - sediment dynamics - pacific oysters - native mussels - habitat - estuary - stabilization - enhancement - communities - adaptation
Ecosystem engineers that inhabit coastal and estuarine environments, such as reef building oysters, do not only stabilise the sediment within their reefs, but their influence might also extend far outside their reefs, affecting tidal flat morphology and protecting the surrounding soft-sediment environment against erosion. However, quantitative information is largely missing, and the spatially extended ecosystem engineering effects on the surrounding soft-sediment largely unstudied. To quantify this, we measured elevations around eleven natural Crassostrea gigas reefs occurring on tidal flats in the Oosterschelde estuary (the Netherlands). These tidal flats experience strong erosion as a consequence of human interventions in the system. Various reef sizes were chosen to test the proportional effects of reefs on tidal flat morphology. Measurements were used to create 3-dimensional surface maps to obtain properties of the reefs and the surrounding soft-sediment environment. The area of the oyster reefs ranged from 2 to 1,908 m2. Reef length varied between 1 and 61 m, reef width between 1 and 45 m, and reef height between 0.20 and 1.08 m. Reefs varied in shape, going from round shape structures to more elongated ones. We observed elevated areas (>5 cm elevation from the background intertidal slope) on the lee side of all reefs, caused by the interaction between the reef’s structure and locally prevailing wave conditions. The elevated area (i.e. the spatially extended ecosystem engineering effect) affected by the reef was of the same order of magnitude as the reef area. The elevated area was related to reef properties such as reef length, width, and height. Reef length, however, appeared to be the best predictor. These findings contribute to management solutions for coastal adaptation and protection. Our study clearly showed that oyster reefs not only protect the tidal flat under their footprint, but as well an area beyond the boundary of the reef
Salt-marsh erosion and restoration in relation to flood protection on the Wadden Sea barrier island Terschelling
Loon-Steensma, J.M. van; Slim, P.A. ; Decuyper, M. ; Hu, Zhan - \ 2014
Journal of Coastal Conservation 18 (2014)4. - ISSN 1400-0350 - p. 415 - 430.
north norfolk - vegetation - succession - herbivory - estuary - defense - field
This paper explores the impact of erosion and restoration measures on habitat development and on wave damping by a small salt marsh nestled alongside a dike on the Wadden island of Terschelling. The aim is to advance knowledge about the benefits and possible side-effects of salt-marsh restoration. Analysis of a time series of aerial photographs from 1944 to 2010 indicates that the salt marsh decreased steadily in size after maintenance of accretion works was terminated. In the western part of the marsh, which is accessible to sheep, vegetation is low (5–15 cm) and dominated by Salicornia europaea and by Spartina anglica. In the most intensively grazed parts, vegetation is very scarce. The eastern, inaccessible part of the salt marsh is covered by dense patches of the shrubby perennial Atriplex portulacoides and Spartina anglica (15–25 cm in height). SWAN wave models show that wave height at this location is significantly affected by the areal extent of the salt marsh as well as by the vegetation. High or dense vegetation are in the models nearly as effective in damping waves (with an initial height of 0.15 and 0.5 m) as widening the salt-marsh area by 350 m. A low density of low plants, as observed in the grazed part of the marsh, has almost no wave-damping effect. Even under conditions of sea level rise, a broader salt marsh vegetated with high plants significantly affects modelled wave height. Therefore, salt-marsh restoration is an adaptation measure worth exploring, though an array of effect types must be considered.
Avian response to tidal freshwater habitat creation by controlled reduced tide system
Beauchard, O. ; Jacobs, S. ; Ysebaert, T. ; Meire, P. - \ 2013
Estuarine Coastal and Shelf Science 131 (2013). - ISSN 0272-7714 - p. 12 - 23.
bird species-diversity - ecological restoration - benthic invertebrates - managed realignment - estuary - marsh - communities - shorebirds - colonization - assemblages
Human activities have caused extensive loss of estuarine wetlands, and the restoration of functional habitats remains a challenging task given several physical constraints in strongly embanked estuaries. In the Schelde estuary (Belgium), a new tidal marsh restoration technique, Controlled Reduced Tide system (CRT), is being implemented in the freshwater zone. A polder area of 8.2 ha was equipped with a CRT to test the system functionality. Among different ecological compartments that are studied for assessing the CRT restoration success, avifauna was monitored over three years. The tidal regime generated a habitat gradient typical of tidal freshwater wetlands along which the distributions of bird and ecological groups were studied. 103 bird species were recorded over the three years. In addition to many generalist bird species, several specialist species typical of the North Sea coast were present. Thirty-nine species of local and/or international conservation interest were encountered, emphasising the importance of this habitat for certain species. Species communities and ecological groups were strongly habitat specific and non-randomly organized across habitats. Spatiotemporal analyses highlighted a rapid habitat colonization, and a subsequent stable habitat community structure across seasons in spite of strong seasonal species turnovers. Hence, these findings advocate CRT implementation as a means to effectively compensate for wetland habitat loss.
Short and mid-long term effects of cockle-dredging on non-target macrobenthic species: a before-after-control-impact experiment on a tidal mudflat in the Oosterschelde (The Netherlands)
Wijnhoven, S. ; Escaravage, V. ; Herman, P.M.J. ; Smaal, A.C. ; Hummel, H. - \ 2011
Marine Ecology 32 (2011). - ISSN 0173-9565 - p. 117 - 129.
wadden sea - zoobenthic community - physical disturbance - benthic communities - estuary - fauna - recruitment - predation - nutrients - habitats
To study the possible environmental impact of hydraulic cockle-dredging on macrobenthic communities and the environment, a fishing experiment was executed on a tidal mudflat in the Oosterschelde (SW Netherlands) according to a BACI (before-after-control-impact) design. Following the characterization of the initial situation, a part of the mudflat was commercially fished, after which dredged and undredged areas were compared on the basis of macrofauna descriptors and sediment constitution approximately 2 months (short term) and 1 year (mid-long term) after fishing. Whereas a clear reduction of the larger Cerastoderma edule cockles (>23 mm) in the fished areas was found, no effect of dredging on total macrofauna densities or median grain size was observed. No negative effect of fishing on total macrofauna biomass was found; in contrast, an increase of the biomass of the non-target species almost compensated for the loss in weight due to the extraction of the larger cockles. No significant effect of dredging on species diversity, richness or evenness was found in the short or mid-long term, these descriptors tending to have increased rather than decreased in the dredged plots after 1 year. The selective fishing for larger cockles reduced the average cockle size, but 1 year after fishing the average size had returned to the initial values in the dredged area. However, compared to the control area, the average size might still be reduced, as the size of the cockles in the control area also increased during the year. Local environmental conditions, with their specific macrobenthic communities, seem to be crucial for the type of effects and the impact of dredging. It is therefore of eminent importance to follow a research design with pre-defined environmental conditions, rather than a comparison of different areas that are open or closed to fisheries. The present study based on a BACI approach indicates that mechanical cockle fisheries had no overall negative impact in our study area.
Preliminary results of a finite-element, multi-scale model of the Mahakam Delta (Indonesia)
Brye, B. de; Schellen, S. ; Sassi, M.G. ; Vermeulen, B. ; Karna, T. ; Deleersnijder, E. ; Hoitink, A.J.F. - \ 2011
Ocean Dynamics 61 (2011)8. - ISSN 1616-7341 - p. 1107 - 1120.
mesh generation - makassar strait - circulation - estuary - ocean - river - rofi - sea
The Mahakam is a 980-km-long tropical river flowing in the East Kalimantan province (Borneo Island, Indonesia). A significant fraction of this river is influenced by tides, the modelling of which is the main subject of this study. Various physical and numerical issues must be addressed. In the upstream part of the domain, the river flows through a region of three lakes surrounded by peat swamps. In the lowland regions, the river is meandering and its hydrodynamics is mostly influenced by tides. The latter propagate upstream of the delta, in the main river and its tributaries. Finally, the mouth of the Mahakam is a delta exhibiting a high number of channels connected to the Makassar Strait. This article focusses on the flow in the delta channels, which is characterised by a wide range of time and space scales. To capture most of them, the depth-integrated and the section-integrated versions of the unstructured mesh, finite-element model Second-Generation Louvain-la-Neuve Ice-Ocean Model are used. Unstructured grids allow for a refinement of the mesh in the narrowest channels and also an extension of the domain upstream and downstream of the delta in order to prescribe the open-boundary conditions. The Makassar Strait, the Mahakam Delta and the three lakes are modelled with 2D elements. The rivers, from the upstream limit of the delta to the lakes and the upstream limit of the domain, are modelled in 1D. The calibration of the tidal elevation simulated in the Mahakam Delta is presented. Preliminary results on the division of the Eulerian residual discharge through the channels of the delta are also presented. Finally, as a first-order description of the long-term transport, the age of the water originating from the upstream limit of the delta is computed. It is seen that for May and June 2008, the time taken by the water parcel to cross the estuary varies from 4 to 7 days depending on the channel under consideration.
Growth of cockles (Cerastoderma edule) in the Oosterschelde described by a Dynamic Energy Budget model
Wijsman, J.W.M. ; Smaal, A.C. - \ 2011
Journal of Sea Research 66 (2011)4. - ISSN 1385-1101 - p. 372 - 380.
individual-based models - crassostrea-gigas - sw netherlands - pacific oyster - shellfish - estuary - culture - mussels - marine - stock
A Dynamic Energy Budget (DEB) model for cockles is presented and calibrated using detailed data on cockle growth and water quality in the Oosterschelde. Cockles in the intertidal areas of the Oosterschelde have an important function as a food source for wading birds and as such for the natural values of the ecosystem. In the presented model, special attention is paid to the formulation and parameter estimation of the functional response. With this functional response, the food quantity and quality variables such as Chlorophyll-a, POM, POC and TPM are translated into food ingestion rate for the cockles. The calibration of the specific parameters included in this functional response is done using a detailed, long term dataset (1992–2007) of cockle growth in the Oosterschelde estuary. This dataset gives a good overview of the development of the cockle population in relation to the environmental conditions (food availability and ambient temperature). The DEB model was able to describe the spatial variation in cockle growth in the Oosterschelde as a function of environmental conditions and the parameters of the functional response. Both the data and the model show that growth performance of cockles is highest in the western and central part of the Oosterschelde due to the higher concentrations of Chlorophyll-a, which is an important food source for cockles. The model failed to describe the large variation in ash-free dry weight during the season. It is tested whether this is caused by aggregating the data by running the model for the full life cycle of year class 2001 at a specific location in the western part of the Oosterschelde. Finally, the model simulations have been compared to growth simulations obtained with an existing ecophysiological model for cockles in the Oosterschelde, the COCO model, with identical forcing. The COCO model showed higher growth in terms of shell length compared to the DEB model and the field observations
Estimating total mortality and asympotic length of Crangon crangon between 1955 and 2006
Hufnagl, M. ; Temming, A. ; Siegel, V. ; Tulp, I.Y.M. ; Bolle, L.J. - \ 2010
ICES Journal of Marine Science 67 (2010)5. - ISSN 1054-3139 - p. 875 - 884.
wadden sea - north-sea - population-dynamics - common shrimp - bristol channel - abundance - atlantic - l. - climate - estuary
Total mortality (Z, year–1) of southern North Sea brown shrimp (Crangon crangon) was determined as Z = K, based on the von Bertalanffy length–growth constant (K, year–1) and derived from length-based methods. Mortality estimates were based on length frequency distributions obtained from four long-term dataseries (1955–2006): German Demersal Young Fish Survey, Dutch Demersal Fish Survey, and two German Bycatch series (Büsum and East Frisia). Four methods to estimate and L were evaluated. Highest total mortality (Z = 8 year–1) was estimated for the early 1990s, and the lowest (Z = 4 year–1) for the 1960s. Accounting for these differences, a median Z rather than mean values was calculated for the whole series, and the value ranged from 5.74 (Ssentongo and Larkin method), through 5.65 (Beverton and Holt method) and 5.64 (Jones and Zalinge method), to 5.35 (length-converted catch curves). Over the whole period, an increase in and a decrease in the proportion of shrimps >60 mm in the catch was observed, whereas asymptotic length L remained constant (at 79.3 mm total length)
Seasonal variation of total and biochemically available concentrations of PAHs in a floodplain lake sediment has no effect on the benthic invertebrate community
Lange, H.J. de; Peeters, E.T.H.M. ; Harmsen, J. ; Maas, H. ; Jonge, J. de - \ 2009
Chemosphere 75 (2009)3. - ISSN 0045-6535 - p. 319 - 326.
contaminated sediments - organic-compounds - toxicity - estuary - phase - rhine - bioavailability - netherlands - extraction - abundance
Floodplain areas in the Netherlands are moderately to heavily contaminated with trace metals and organic contaminants. The impact of this sediment pollution on benthic invertebrates is best described with so-called ‘bioavailable’ concentrations instead of total concentrations. Studies into the effect of contaminants on biota are usually a snapshot in time, with one or two samples in a year. In such studies, effect of seasonal variation cannot be detected. Objective of this study was to investigate the temporal variation of sediment PAH contamination in one floodplain lake, and possible consequences for the benthic invertebrate community. This was done by sampling biota, abiotic variables and sediment contaminants every four weeks during one year. We observed a limited seasonal variation in total and bioavailable concentrations of PAHs. Multivariate analysis revealed that the PAH contamination is not a significant factor for the benthic invertebrate community in this floodplain lake. Bioavailable concentrations of PAHs were low and no effects could be expected based on the measured values. No increase of available PAHs was observed in periods where conditions for degradation were absent (low temperature, anaerobic). These results also indicate that in such floodplain lake systems, with historical pollution, the timing of sampling to assess sediment contamination with organic pollutants is of limited importance. This can be useful for planning sampling in risk assessment studies
Temporal variation of trace metal geochemistry in floodplain lake sediment subject to dynamic hydrological conditions
Griethuysen, C. van; Luitwieler, M. ; Joziasse, J. ; Koelmans, A.A. - \ 2005
Environmental Pollution 137 (2005)2. - ISSN 0269-7491 - p. 281 - 294.
zware metalen - geochemie - meren - oppervlaktewater - waterverontreiniging - stroomvlakten - hydrologie - nederland - gelderland - land van maas en waal - heavy metals - geochemistry - lakes - surface water - water pollution - floodplains - hydrology - netherlands - gelderland - land van maas en waal - acid-volatile sulfide - fresh-water sediments - elements - estuary - solids - avs
Climate change and land use may significantly influence metal cycling in dynamic river systems. We studied temporal variation of sediment characteristics in a floodplain lake, including concentrations of dissolved organic carbon, acid volatile sulfide and trace metals. The sampling period included a severe winter inundation and a dramatic water level drop during summer. Temporal changes were interpreted using multivariate analysis and chemical equilibrium calculations. Metal concentrations in sediment increased with depth, indicating a gradual improvement of sediment quality. In contrast, dissolved metal concentrations were highest in top layers due to mobilization from oxyhydroxides and precipitation with sulfides in deeper layers. Inundation had a mobilizing effect as it stimulated resuspension and oxygenation of sediment top layers. Water table lowering combined with organic matter decomposition led to immobilization due to sulfide formation. The chemistry of the sediments was consistent with model calculations, especially for macro-elements. The results illustrate the importance of seasonality for metal risk assessment.
A comparison on accumulation characteristics of 7Be and 137Cs in lake sediments and surface soils in western Yunnan and central Guizhou, China
Bai, Z.G. ; Wan, G.J. ; Huang, R.G. ; Liu, T.S. - \ 2002
Catena 49 (2002)3. - ISSN 0341-8162 - p. 253 - 270.
erosion rates - pb-210 - estuary - tracers - radionuclides - switzerland - cesium-137 - particles - fluxes - th-234
The uplifting of the Himalayas has resulted in the development of a three-tiered landform in Southern China, the Yunnan–Guizhou Plateau is the middle tier of this landform on the eastern slope of the Himalayas. Lake Hongfeng and Lake Baihua in central Guizhou are about 1000 km away from Lake Erhai in western Yunnan. Sediment cores were collected from Lakes Erhai and Lugu in west Yunnan and Lakes Hongfeng and Baihua in central Guizhou, along with 28 surface soil cores from the watersheds of these lakes. The accumulation characteristics of 7xxxxBe and 137yyyyCs show that: (1) 137Cs activities in the soil cores of central Guizhou were higher than that in the western Yunnan. The activities and maximum penetrative depth of 7Be were similar for the two regions. The activity ratio of 7Be/137Cs in surface soil reached 100–1000 in western Yunnan, but only 10–100 for central Guizhou region. (2) 7Be inventories in soil cores at most sampling sites of central Guizhou were low, reflecting severe soil erosion. 7Be inventories in the soil cores of Lake Lugu watershed in summer–autumn were higher than that in Lake Hongfeng/Baihua watershed and also higher than that in Lake Erhai watershed. This could be related to high 7Be precipitation in summer and altitude. (3) 7Be inventories in sediment cores of Lake Erhai, Lake Lugu and Lake Baihua were 237±73, 322±19 and 783±44 Bq m-2, respectively. Based on activity values that were corrected to deposition, prior to 1986, 137Cs inventories in these lakes were 519±26, 937±13 and 3704±56 Bq m-2, respectively. (4) Modeling indicated that 7Be and 137Cs accumulations in Lake Hongfeng and Lake Baihua were dominated by watershed erosion, and controlled by the retention factor in Lake Erhai and Lake Lugu, but the 137Cs inventory ratios obtained in the sediment core and from direct atmospheric fallout were similar, and the ratios were smaller for 7Be. (5) 7Be inventories from direct atmospheric fallout in Lake Erhai, Lake Lugu and Lake Baihua were 0.07±0.02, 0.29±0.02 and 0.08±0.01 Bq m-2, respectively. Prior to 1986, 137Cs inventories were 0.11±0.01, 0.22±0.01 and 0.37±0.01 Bq m-2, respectively, showing that 137Cs deposition has a regional difference. This phenomenon may reflect that uplift of the Himalayas has a screening effect on the fallout of globally distributed atmospheric pollutants in western Yunnan, China.