Exploring the topographical pattern beneath the water surface: Global bathymetric volume-area-height curves(BVAH) of inland surface water bodies

Global inland surface water bodies such as lakes and reservoirs,important components of the hydrosphere and ecosphere,are increasingly affected by climate change.Generating bathymetric volume-areaheight (BVAH) curves for global inland surface water bodies can enhance our understanding of their topography and climate impacts.However,accurately quantifying the topographic patterns of these water bodies remains challenging due to the difficulties in collecting comprehensive bathymetric data.Therefore,we collected and processed over 2000 bathymetric maps of global water bodies from over 50 different data sources and then developed the BVAH model.Finally,the BVAH hydrological curves of 16671 global inland surface water bodies (larger than 10 km~2) were generated.The results include but are not limited to (1) For most targeted water bodies,area (A) and volume (V) exhibit significant power function relationships with surface heights (H),with optimal power values quantified as 1.42 for A and 2.42 for V.(2) The BVAH model outperforms GLOBathy in estimating area and volume changes,achieving higher correlation coefficients (CC) of approximately 0.962 for the area and 0.991 for volume,and demonstrating lower percentages of root mean squared errors (PRMSE) around 10.9% for the area and 4.8% for volume.(3) In the case study of the Xizang Plateau and various large global reservoirs,the BVAH curve database can capture dynamic volume changes.As a unified simulation of the bathymetric topographical patterns,our bathymetric dataset and corresponding BVAH curve database have great potential to contribute to effective water resource management and ecological conservation efforts worldwide.

Geolocator study reveals east African migration route of Central European Common Terns

Background: The majority of European Common Terns(Sterna hirundo) migrate south along the western coast of Europe and Africa, while birds from eastern regions are known to cross the Mediterranean Sea from east to west or migrate along the eastern African coast. The migration route of north European terns wintering along the coast of western Africa was already described using geolocator data, while knowledge about movements of the European inland populations is based only on relatively scarce recoveries of ringed birds.Methods: We used light-level geolocators in inland Common Tern colonies in Hungary and Croatia to study their migration route and to identify wintering areas along with stopover sites. Results revealed by geolocators were compared with recoveries of ringed birds.Results: All tracked birds used the east African migration route with autumn stopovers at Lower Nile and in the southern part of the Red Sea, and short spring stopover in Israel. Terns wintered along Kenyan coasts and in the southern Mozambique Channel. Autumn migration lasted four times longer than spring migration.Conclusions: This is the first geolocator study that describes the east African migration route of the Common Tern. Important stopover sites were identified. More studies of inland populations are needed to better elucidate tern winter movements.

Management options for the unfavorable nutrient balance of recreational fishing in Lake Balaton(Hungary)

Various types of ground baits are loaded to lakes by anglers,but the ecological role of these materials is often overlooked.Thus,the aims of this study were to conduct a quantitative and qualitative assessment of the baits used by anglers in the largest lake of Central-Europe(Lake Balaton,Hungary),estimate the annual nutrient balance of recreational fishing,and relate the nutrient loading from this source to the total external load.Our study demonstrated that popular angler baits varied substantially in their nutrient contents and in their molar nitrogen to phosphorus(N:P)ratios.The net nutrient balance of recreational fishing was+19.3 t total N year^(-1)and+5.2 t total P year^(-1),equivalent to 0.7%and 3.2%of the estimated total annual N and P loads,respectively.The rate of nutrient loading may be doubled if the present trends continue:anglers will use 20%more bait with an even higher nutrient content and will also show higher propensity to release the fish after catching.In turn,sustainable nutrient balance of fisheries management could be achieved by limiting the anglers’bait use to 1.5 kg day^(-1)and restricting baits to those which have relatively low P(<0.3%)and N(<1.5%)contents.

Screening potential genotoxic effect of aquatic plant extracts using the mussel micronucleus test

Objective:To assess the genotoxic potential of selected aquatic macrophytes:Ceratophyllum demersum L.(hornwort,family Ceratophyllaceae),Typha angustifolia L.(narrowleaf cattail,family Typhaceae),Stratiotes aloides L.(water soldier,family Butomaceae),and Oenanthe aquatica(L.)Poir.(water dropwort,family Umbelliferae).Methods:For genotoxicity assessment,the mussel micronucleus test was applied.Micronucleus frequency was determined from the haemolymph of Unio pictorum L.(painter’s mussel).In parallel,total and hydrolisable tannin contents were determined.Results:All plant extracts elucidated significant mutagenic effect.Significant correlation was determined between tannin content and mutagenic capacity.Conclusions:The significant correlation between genotoxicity as expressed by micronucleus frequency and tannin content(both total and hydrolisable tannins)indicate that tannin is amongst the main compounds being responsible for the genotoxic potential.It might be suggested that genotoxic capacity of these plants elucidate a real ecological effect in the ecosystem.