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Algal diversity in aquatic environments can help assess the health status of ecosystems, provide information about invasions of new species and inform species diversity changes according to environmental conditions. An algal diversity survey (2016–19) of Nador Lagoon (northern Morocco) revealed the presence for the first time of the brown alga Cystoseira aurantia. Since 2015 this alga has been found in high abundance in the northwestern part of the lagoon, mainly around Attalayoun and Nador City. The thalli of larger specimens reached 60 cm in length, and all plants present were free-floating. The species was collected from the water surface to depths not exceeding 2 cm. Floating patches were usually found suspended above sandy and muddy substrates. Increased abundance of this species in the lagoon corresponds with new physico-chemical conditions and ecological parameters, principally resulting from increased water ventilation and improved water quality since 2012. The new communities of C. aurantia may offer a novel resource for the lagoon but high abundance could pose future threats to attached vegetation such as seagrasses and benthic algae by shading and the accumulation of organic detritus. Attention is drawn to taxonomic issues involving C. aurantia.

There are relatively few Holocene lake sediment core sequences available for north-east Africa. This study examines the developmental history of Faiyum Lake (Egypt) by detailed lithostratigraphic description together with microfossils and geochemistry, of two adjacent lake sediment cores. The recovered sedimentary sequence consists of predominantly lacustrine facies divisible into five sedimentary units. Early Holocene sediments (Unit II; c. 9.9–8 ka cal BP), overlying late Pleistocene aeolian sands (Unit I), comprise sub-mm laminations (non-glacial varves) of white diatomite and calcite inter-bedded with yellowish-green mineralogenic layers indicating a deep freshwater lake phase. Early middle Holocene sediments (Unit III, c. 8 to 6 ka cal BP) consists by pockets of non-glacial varved laminae intercalated with turbidites and increasing thick silty clay layers, indicating a shallow freshwater lake phase with increasing nutrients. The late middle Holocene lake phase, Unit IV (c. 6 to 4 ka cal BP) is grey massive mud with occasional thick (>1 cm) diatomite-carbonate layers and thin gypsum and iron-hydroxides layers indicative of a lake shrinking phase but with a large level fluctuation sand evaporation phases when freshwater inflow diminished. The late Holocene lake phase (unit V, c. 4 ka cal BP-present) reveals bioturbation and increasing fine sand with artifacts corresponding to further lake level declines and fluctuations as water management intensifies during and after Middle Kingdom and Ptolemaic times. Together with geochemical and microfossil evidence, sedimentology of the studied cores indicate a series of major environment changes affecting the whole lake system throughout the Holocene.

The degree to which climate variability and anthropogenic stressors have impacted the rich array of boreal lakes in northern Saskatchewan and Alberta was explored in a dataset of 42 lakes from previous paleolimnological investigations of this region. This dataset was used to evaluate the extent of change in diatom assemblages over the past ~ 60 to 70 years in relation to lake and watershed characteristics. Similarity analysis was used to define the degree of change in diatom composition in lake sediment cores from each lake with a focus on post ca. 1945 changes to establish a common time frame to compare across all lakes. This time frame incorporates pre- and post-development of the Athabasca Oil Sands Region and additionally integrates pre- and post-periods of distinct changes in temperature and precipitation. Beta regression analysis was used to identify potential links between diatom assemblage change and lake physical–chemical and landscape characteristics (limno and landscape models, respectively). Similarity analysis indicated nearly 80% of the lakes showed only a very low degree of change (0–25%) since ca. 1945. Lakes with larger percent change in similarity (> 25%) showed increases in planktonic diatoms, although the specific taxa that changed varied from oligotrophic Discostella spp. to meso-eutrophic taxa, such as Asterionella formosa and Stephanodiscus minutulus. Lake volume and percent peat in the catchment were the most important limno and landscape explanatory variables, respectively, albeit the models had low predictive power. The lakes with large diatom compositional change were dispersed across the region, located in various geological and ecological zones and varying degrees of human disturbance. The interplay of climate and morphometric features of lakes is likely an influential driver of these changes, with larger heat-storage capacity in higher-volume lakes that potentially increases the sensitivity to warming. The small surface areas and shallow morphometry of most lakes, a heterogeneous hydrological and geological landscape, and frequent dominance of diatom assemblages by benthic generalists may explain the minimal responses of diatom assemblages over the past ~ 70 years to anthropogenic influences and climate.

China has been committed to achieving carbon neutrality by 2060. China's pledge of carbon neutrality will play an essential role in galvanising global climate action, which has been largely deferred by the Covid-19 pandemic. China's carbon neutrality could reduce global warming by approximately 0.2-0.3 °C and save around 1.8 million people from premature death due to air pollution. Along with domestic benefits, China's pledge of carbon neutrality is a "game-changer" for global climate action and can inspire other large carbon emitters to contribute actively to mitigate carbon emissions, particularly countries along the Belt and Road Initiative (BRI) routes. In order to achieve carbon neutrality by 2060, it is necessary to decarbonise all sectors in China, including energy, industry, transportation, construction, and agriculture. However, this transition will be very challenging, because major technological breakthroughs and large-scale investments are required. Strong policies and implementation plans are essential, including sustainable demand, decarbonizing electricity, electrification, fuel switching, and negative emissions. In particular, if China can peak carbon emissions earlier, it can lower the costs of the carbon neutral transition and make it easier to do so over a longer time horizon. China's pledge of carbon neutrality by 2060 and recent pledges at the 26

Macroinvertebrate communities are strongly influenced by hydrological variability in surface waters. However, the response of these communities in corresponding groundwater-dependent habitats is not well understood. This study characterised the macroinvertebrate fauna and physicochemical characteristics of a chalk aquifer and its rivers in southern England. Over one year, samples were collected from five paired benthic-hyporheic sites located in perennial or temporary rivers, and a further seven phreatic sites in the surrounding aquifer. The study was preceded by a period of below average rainfall, providing an opportunity to assess the response of macro-invertebrate communities to unseasonal declines in river discharge and groundwater levels. Benthic, hyporheic and phreatic habitats each supported a distinct macroinvertebrate community, with the hyporheic habitat support- ing both epigean taxa and stygofauna. As discharge declined, the composition of these communities changed. In particular, the abundance of the epigean amphipod Gammarus pulex was higher in hyporheic than benthic habitats during periods of low river discharge, suggesting potential refuge-seeking behaviour. Similarly, fluctuations in the abundance and distribution of two stygofauna, Crangonyx subterraneus and Niphargus fontanus, coincided with marked changes in groundwater levels, suggesting that the contraction of available habitat and changes in connectivity also influenced the phreatic community. The variable distribution of macroinvertebrates between these habitats, especially in response to hydrological variability, suggests a dynamic connection between the river and its aquifer. This connection is an important consideration for the assessment and conservation management of both surface and groundwater communities and may help underpin integrated, catchment-based management, especially in river systems with temporary reaches.

Amphorotia is a diatom genus of considerable morphological and biogeographical significance. It was established by transferring several Eunotia species and describing several new species. The most species were found dispersed towards Southeast Asia. In coastal areas of China, a number of species of Amphorotia were found and the assemblages contained several new taxa. This article provides additional information on five previously described species and describes one new species, Amphorotia zhujiangensis sp. nov., and one uncertain but special species, A. sp. These are based on fossil material from a deltaic borehole, subaquatic sediment cores and surface sediments collected in the Pearl River estuary region. Morphological data were derived from light and scanning electron microscopy. A detailed morphological comparison of seven Amphorotia species is included, indicating the existence of a diverse group in brackish waters. Relationships within the family Eunotiaceae are briefly discussed. The biogeo...

The giant ibis (Thaumatibis gigantea), Cambodia’s national bird, is edging toward extinction. The ibis’s historical range stretched across Southeast Asia, but only 194 critically endangered individuals remain, constrained to the northeastern region of Cambodia. The small population suffers from habitat loss and disturbance caused by human activities, and tensions between humans and wildlife have escalated during the coronavirus disease 2019 (COVID-19) pandemic. In April, 3 giant ibises and more than 100 other birds were poached in Cambodia’s Chhep Wildlife Sanctuary. To save the giant ibis, conservation efforts must continue, even during the pandemic.

An inventory of Lepidoptera in the Theniet El Had National Park (PNTEH), Algeria, revealed 86 taxa, both butterflies and moths. The specimens were collected in 68 localities distributed over ten cantons within the park in the period 2015–2017. A preliminary faunistic list is compiled as a base-line contribution to the study of adult Lepidoptera in this park. In total, 3139 specimens were collected. The moths are clearly well diversified, with 14 families and 49 species obtained from a total of 1485 adult specimens. The butterflies are represented by 5 families with 37 species and 1654 specimens. A total of 8 families are reported for the first time from this park, in order of abundance: Zygaenidae, Hesperiidae, Crambidae, Alucitidae, Heterogynidae, Sesiidae, Oecophoridae, and Cossidae. Also 61 species are recorded here for the first time for the park. The most diverse family is Nymphalidae with 15 taxa (23% of the total species). On the other hand, the Erebidae are represented by 894 specimens (28.5% of the total number of specimens. Within the Erebidae, the genus Catocala contains the highest number of individuals (794 specimens). The canton of Pré-Ben Chouhra is quantitatively the best represented with 625 specimens (19.9% of the total number of specimens collected) and the Nursery canton as the richest in lepidopteran species with 72 species observed. The diversity indices (H’ and Hmax.) and the equitability index (E), calculated for the 10 cantons indicate that lepidopteran species are diverse in each station.

A suite of drill cores undertaken on the Saqqara-Memphisfloodplain revealed an array of Late Pleistocene-Holocene sediment facies that show a complex of spatio-temporal changes in sediment related to migration of the River Nile, Nile flood variations, settlement sites and climate change. The recovered data enhance our understanding of the history of the modern River Nile and its relationship to the emergence and continuity of Egyptian civilization. The floodplain of the Saqqara-Memphis area reveals a sequence of aggradation and degradation events comprising six clearly marked sedimentary units (I-VI), overlying Late Pleistocene fluvial sand and gravel (unit I). Deposition of unit II resumed during a period of high Nile flow, rapid sea level rise and locally wet climatic conditions. As a result, the floodplain was occupied by swamps and anastomosing channels. Subsequently, the Nile changed to a more stable meandering channel system with well-developed levees and flood basins (unit III). This aggradation unit was subsequently eroded by the end of Old Kingdom (ca. 4.2 kyr cal BP). The degradation hiatus was followed by a widespread layer of alluvial silt and sand indicating very high Nile floods that coincide with historical records of very high floods during the Middle Kingdom and frequently high floods during the New Kingdom (unit IV). During the last two thousand years (units VI-VII) floods generally diminished except for several notable lows and highs. Our calculations of the long-term rate of siltation during the Middle and Late Holocene suggest an average rate of 0.235 m/century rather than the commonly cited 0.09–0.12 m per century. In addition, our study of satellite imagery of the Memphite region in the context of archaeological data combined with our own geological studies reveal that the main Nile in Neolithic and Predynastic times (ca.7.0–5.0 kyr cal BP) ran along the eastern edge of the current floodplain. A lateral branch of the Nile ran along the western edge of the floodplain. It is on the bank of this branch that the first capital of a unified Egypt was established. Our cores also reveal during the Dynastic period, the western branch shifted eastwards, while the main Nile shifted westwards.

On December 20, 2015 at 11:40 am a landslide in one of China's most advanced cities, Shenzhen, killed 73 people and damaged 33 buildings. In the absence of heavy rainfall or earthquakes, the landslide was an unexpected and profound shock to many people. According to China's Ministry of Land and Resources, the landslide was triggered by the collapse of an enormous pile of construction and demolition waste (CDW). With China's rapid urbanization, an increasing amount of CDW is being generated, especially in major cities. In total, China produces some 30% of the world's municipal solid waste and of this about 40% is CDW. To prevent landslides associated with CDW, the volume of waste dumped in landfills should be regulated. More specifically 4-Rs (reduce, reuse, recycle and recover) policies should be implemented more widely and efficiently. Although landfill will continue to be an important disposal option, proper management and careful monitoring of CDW are urgently needed to satisfy pressing safety issues. International collaboration, sharing of knowledge, and use of the latest technologies are needed so that the similar landslides can be prevented in China and elsewhere.

Riparian depressional wetlands (haors) in the Upper Meghna River Basin of Bangladesh are invaluable agricultural resources. They are completely flooded between June and November and planted with Boro rice when floodwater recedes in December. However, early harvest period (April/May) floods frequently damage ripening rice. A calibrated/validated Soil and Water Assessment Tool for riparian wetland (SWATrw) model is perturbed with bias free (using an improved quantile mapping approach) climate projections from 17 general circulation models (GCMs) for the period 2031–2050. Projected mean annual rainfall increases (200–500 mm or 7–10%). However, during the harvest period lower rainfall (21–75%) and higher evapotranspiration (1–8%) reduces river discharge (5–18%) and wetland inundation (inundation fraction declines of 0.005–0.14). Flooding risk for Boro rice consequently declines (rationalized flood risk reductions of 0.02–0.12). However, the loss of cultivable land (15.3%) to increases in permanent haor inundation represents a major threat to regional food security.

China has at least 30 oyster species, all of which provide valuable ecosystem services. Oysters’ filter feeding habit reduces suspended particles and nutrients. One hectare of oyster reef can clean a volume of water equivalent to nearly 15 Olympic swimming pools daily. Oysters’ excrement can stimulate denitrification by removing nitrogenous organic matter, helping to mitigate eutrophication. Natural oyster reefs provide habitat for many species, enhancing biodiversity and increasing fisheries. Oyster reefs can reduce impacts of waves caused by hurricanes and typhoons, stabilizing shorelines. Despite their ecological importance, 85% of oyster reefs globally have been degraded since the 19th century by overharvesting, coastal development, water pollution, and disease. China’s oyster reefs, especially those in Tianjin and Jiangsu, have been seriously damaged during recent decades. Urgent action by Chinese authorities is required to protect these crucial species.

A personal summary of paleolimnological research activities in the UK and elswehere since the mid 1970s.

The genus Amphorotia Williams & Reid (2006) was established to accommodate a group of diatoms formerly allocated to Eunotia Ehrenberg. The new genus was shown to display a distinct biogeographical distribution. To increase the knowledge of this genus, especially in China, a taxonomic investigation of Amphorotia in the Pearl River delta area was undertaken using borehole materials. This paper reports and describes specimens of an uncommon species of Amphorotia extracted from sediment samples using a special concentration technique. Morphological data derived from both light (LM) and scanning electron microscopy (SEM) are used to characterise the specimens. Based on these observations, an emended description of a species formerly reported from the same region, Amphorotia curvata Williams & Reid, is provided and its neotype is established. The new Pearl River specimens are all attributed to A. curvata and this species is compared to other Amphorotia species from China, Southeast Asia and Lake Baikal. It is s...

We report on the sedimentology, pollen and diatom records in a 26 m long core of Holocene sediments from the Tersa area, near the centre of the Faiyum Depression (Egypt). Two radiocarbon and one OSL dates have been obtained for the core, dates range from 9545 ± 60 Cal. BP to c. 4040 BP. These correspond respectively with the Terminal Palaeolithic (Qarunian) and Neolithic Faiyum A (Faiyumian) cultures. The core is subdivided into 3 sedimentological units: unit 1 (21–26 m) is very thinly laminated, calcareous silt deposited in a deep water lake; unit 2 (9.5–21 m) is finely laminated sand, silt and carbonates formed as a lacustrine fan delta; unit 3 (9.5 m to the core top), is formed of massive silt, sandy silt and very fine grained flood plain sands. Planktonic diatom taxa, mainly Cyclostephanos, Aulacoseira, Cyclotella and Stephanodiscus spp. were abundant in units 1 & 2-a, indicating deep, open lake conditions. Magnetic minerals increased from the base of unit 2 indicating an increasing contribution of Nile alluvium. Benthic taxa such as Fragilaria, Cocconeis , Amphora and Navicula tended to increase towards the core top, from unit 2-b; 3-a to 3-b, indicative of lake shallowing and periods of low Nile floods. Unit 3-c is barren of diatoms and is compatible with terrestrial flood plain conditions. Vegetation was mainly represented by herbaceous pollen throughout most of the core and in the topmost sediment, pollen was scarce but pteridophyte (Osmundaceae) spores increased. Arboreal vegetation had low percentages in most of the record but increased in the middle section of the core (unit 2). A depositional deltaic environment was indicated throughout most of the core (sub-units 2-a & 3-a), where high abundances of Poaceae, Cyperaceae, Chenopodiaceae, Amaranthaceae, Polypodiaceae and Osmundaceae were recorded, indicating high Nile floods and fluctuating rainfall.

During most of the Holocene, the Faiyum Depression in Middle Egypt was connected to the Nile River and contained an extensive freshwater lake. Geochemical analysis of a lacustrine sediment core (Qaru-9) from the depression provides evidence of changes in Nile sediment discharge related to changes in Ethiopian African Monsoon (EAM) precipitation, and allows us to reconstruct changes in Nile River runoff, vegetation and erosion in both the near and far catchment. Major and trace elements reveal significant changes in clastic sediment provenance, with sources oscillating between (i) a Blue/Atbara Nile fluvial contribution during the African Humid Period (AHP) and in the late Holocene (i.e. c. 10–7.5 & c.4–0 ka cal BP, respectively), (ii) a White Nile contribution between c. 7.5–4 ka cal BP with aeolian contributions and carbonate deposits occurring during local arid and wetter conditions, respectively. We also use geochemical data to assign variations in the paleowater properties of the Faiyum Lake (i.e. redox condition, paleosalinity and paleoproductivity) throughout the Holocene. Changes in pollen and algal remains in early to mid Holocene sediments confirm a deep freshwater lake prior to c. 10–8 ka cal BP but diminishing water levels after this period. The Faiyum Lake was a deep freshwater lake between 10 & 6 ka cal BP with fluctuating lake levels between 6–4 ka cal BP and during the late Holocene. In the later period, an abrupt drop in lake level occurred followed by increasing salinity as hydrological modifications occurred.

The expansion of transport infrastructure endangers many wild places, particularly in the tropics (“Roads to riches or ruin?,” W. F. Laurance and I. Burgues Arrea, Perspectives, 27 October 2017, p. [442][1]). Opening transport routes through the Arctic is also likely to damage fragile

We present results of mineralogical (light, heavy and clay minerals), geochemical and palynological investigations of floodplain sediments at Saqqara. Our investigations provide new insights into our understanding of the source of the Holocene Nile sediments, local palaeoclimate and palaeoenvironment of the floodplain at Saqqara as well as the Holocene palaeoclimatic variations at the Nile headwaters. We also investigate the relationship between Nile floods and global climate changes and the impact of changing flood conditions on episodes of societal and central governmental collapse at the end of the Egyptian Old Kingdom. The Holocene sequences recorded in two shallow drill cores (SAQA 21 and 22) were investigated and subdivided into six sedimentary units, from underlying Late Pleistocene sand and gravels (unit I) to overlying modern soil (unit VIII). Early Holocene sediments were essentially missing in the studied cores, probably due to intensive erosion during the well-known 8.2 kyr cal BP arid event. Middle Holocene sediments are represented by unit II, which reflect high Nile floods of Equatorial African origin with less contribution from Ethiopian sources. The Old Kingdom sediments (unit III), seems to be mainly of White Nile sources with frequent contributions from the Blue Nile. Late Holocene sediments (unit IV-VII) show an increased contribution from Blue Nile River sources. Low Nile flow episodes were recorded at 5.2 (between units II and III), 4.2 (between units III and IV), 3.5 (within unit IV) and 2.7 kyr cal BP (between units V and VI). The second event corresponds to the First Intermediate Period (FIP) and the third probably coincides with the Second Intermediate Period (2nd IP), periods of disorder in Egypt.

Techniques used to extract shale gas, hydraulic fracturing or fracking, do have draw-backs not least the large consumption of water. We provide the first estimate of water consumption in Chinese shale gas fracking. A case study from Fuling, Chongqing, Southwest China, shows that average water consumption is 27490 m3 per well, much higher (by 29%-160%) than in the USA. Data analysis indicates a significant correlation between water consumption and lateral length of wells (p

This study focused on the analysis of organochlorine pesticides and PCBs in tissue samples of the clam, Ruditapes decussatus, in the Oualidia lagoon. Tissue assays were conducted during February to December 2005 and sediment (October 2005) was also tested. 13 organochlorine compounds and eight PCBs congeners were investigated, is HCB, γ-HCH, chlordane, cis-chlordane and trans-nonachlor, DDT and its metabolites DDD, DDE, heptachlor, its epoxide, mirex and PCBs (PCB28 + 50, PCB52, PCB101, PCB 118, PCB138, PCB153, PCB180). Analysis of these compounds was performed using a gas chromatography capillary column and an electron capture detector. Organochlorine contamination of clams and sediments in the lagoon did not exceed tolerable thresholds according to European standards. The levels of tPCB, tDDT and tOCP in clams are high at 49.4, 22.2, and 7.1 ng g(-1) dw respectively. Concentrations of trans nonachlor and mirex are low compared to other chlorinated pesticides. PCB28 + 50, PCB52 and PCB101 show typical values in sediment, at 18.5, 10.8 and 17.8 ng g(-1) dw respectively.

With rapid population growth, especially in low-income and middle-income countries, the generation of waste is increasing at an unprecedented rate. For example, annual global waste arising from waste electrical and electronic equipment alone will have increased from 33.8 to 49.8 million tonnes between 2010 and 2018. Despite incineration and other waste treatment techniques, landfill still dominates waste disposal in low-income and middle-income countries. There is usually insufficient funding for adequate waste management in these countries and uptake of more advanced waste treatment technologies is poor. Without proper management, many landfills represent serious hazards as typified by the landslide in Shenzhen, China on 20 December 2015. In addition to formal waste recycling systems, approximately 15million people around the world are involved in informal waste recycling, mainly for plastics, metals, glass and paper. This review examines emerging public health challenges, in particular within low-income and middle-income countries, associated with the informal sector. While informal recyclers contribute to waste recycling and reuse, the relatively primitive techniques they employ, combined with improper management of secondary pollutants, exacerbate environmental pollution of air, soil and water. Even worse, insufficient occupational health measures expose informal waste workers to a range of pollutants, injuries, respiratory and dermatological problems, infections and other serious health issues that contribute to low life expectancy. Integration of the informal sector with its formal counterparts could improve waste management while addressing these serious health and livelihood issues. Progress in this direction has already been made notably in several Latin American countries where integrating the informal and formal sectors has had a positive influence on both waste management and poverty alleviation.

Despite the moratorium on fishing in China's coastal waters (“China cracks down on coastal fisheries,” D. Normile, In Depth, 12 May, p. [573][1]), the nation's fisheries remain under threat by fuel subsidies. Because of the money saved on fuel, commercial fishermen can afford to use more ships

Evaluating the significance of protected areas for biodiversity and ecosystem services is important for nature conservation. In a recent issue of PNAS, Xu et al. (1) present valuable information on provision of biodiversity and ecosystem services by China’s nature reserves. They conclude that reserves serve bird populations moderately well. However, the importance of coastal wetlands for migratory birds and the shortage of protected coastal sites are underplayed. Migratory birds rely on networks of strategically located sites across their annual migration cycle. Loss or degradation of any one site can impact bird populations (2). In comparison to many studies, including the study of Xu et al. (1), which either omit parts of the annual migration or treat species’ distributions as static, Runge et al. (2) analyzed 520 bird species and found that protected areas covered only … [↵][1]1To whom correspondence may be addressed. Email: hongyanghy{at}gmail.com or mmg{at}swu.edu.cn. [1]: #xref-corresp-1-1

We assess the recovery of UK lakes from acidification using the combined data from sediment cores and sediment traps to track changes in diatom assemblages in 11 UK upland lakes from pre-acidification times (prior to ca. 1850 AD) to the present (2008 AD). We projected the data into a Principal Component Analysis (PCA) of diatom assemblage data from 121 low-alkalinity lakes in the UK to show how the floristic composition of the core and trap diatom assemblages for each site has changed through time. The results show that the degree of recovery from acidification varies amongst sites but in all cases its extent is limited when compared with the pre-acidification reference. In most cases the recovery, although usually slight, is characterised by a decline in acid tolerant taxa and a return towards taxa that occurred previously at each respective site. In a few cases, however, the floristic composition of recent samples is different from those that occurred during and before the acidification phase. The reasons for this are not yet clear but it is possible that nutrient enrichment from atmospheric N deposition and/or climate change is beginning to play a role in driving water quality as acidity decreases. More generally the results show that annually recovered samples from sediment traps can be successfully combined with sediment core data to provide a continuous record of environmental change in lake systems, and that diatoms collected in sediment traps can be used to provide a very powerful lake monitoring tool.

Potsherds recovered from the Saqqara–Memphis floodplain in Egypt, dated according to their typology and radiocarbon dating of the included sediments, are analysed geochemically and mineralogically to identify source materials and fabrication characteristics. Pottery layers were identified and potsherds were recovered from several settlement levels. Sherd typology was used to identify sherds from four periods (the Old and New Kingdoms, and from the Late Period to the Ptolemaic). The Pharaonic pieces were found at depths of between 8 and 12 m and the later material was between 6 and 3 m. Chemical analyses of the potsherds revealed three main source materials: local Nile silt, marl clay and mixed Nile silt–marl. Two marl clay types were recognized: marl clay from Upper Cretaceous marine sediment and another one from Late Pliocene deltaic sediments. The mineralogical composition of the pottery samples shows that the estimated firing temperature was about 850–900°C. No consistent differences in sherd mineralogy and geochemistry were found according to pottery types, so that the ancient Egyptian potters used essentially the same materials throughout the Pharaonic period. However, this initial study has revealed the existence of extensive pottery-rich occupation sites buried within the Nile floodplain deposits between Memphis and Saqqara.

Diatom preservation can be a major taphonomic issue in many lakes but is often unrecognised and its impacts on qualitative and quantitative inferences (such as productivity and biodiversity estimates) from sedimentary archives are seldom explored. Here two palaeolimnological case studies of 20th-century anthropogenic eutrophication of freshwater lakes in Northern Ireland (Lough Neagh and Lough Augher) are re-visited and new data presented on diatom preservation. Assessing problems of taphonomy challenges previous interpretations of silica dynamics and diatom productivity at these sites. Diatom preservation was assessed in both sediment trap material and sediment cores from Lough Neagh, and in sediment cores from Lough Augher. Preservation data, combined with geochemical analysis (Si, Fe), provide an insight into silica cycling and diatom accumulation over a range of temporal scales from these lakes. Diatom preservation was generally good for the Lough Neagh material, although differential (better) preservation of the smaller Aulacoseira subarctica compared to the larger Stephanodiscus neoastraea sensu lato valves was clear, especially in sediments. Porewater silica showed a complex seasonal pattern in the upper sediment, against expectations of steady-state. The Lough Augher material was generally poorly preserved, although preservation (dissolution) was significantly (and positively) correlated to bulk sedimentation rate, and was found to be a major control on (net) diatom accumulation rate across the basin. Past seasonal and severe anoxia at Lough Augher did not improve diatom preservation, contrary to some previous studies, which may be due to extreme changes in sedimentary redox conditions. Finally, using published experimental relationships between dissolution and diatom valve loss, correction factors were applied to previously published profiles of diatom accumulation over the last ~150 years (biovolume from Lough Neagh and frustule accumulation rate from Lough Augher), which suggest that diatom productivity estimates from sedimentary records are underestimated by a factor of 2–4 due to dissolution effects alone. The results clearly have implications for the reliability and accuracy of diatom-based inferences made from sediment records, both qualitative and quantitative, especially for those that employ diatoms as direct measures of productivity or biodiversity.

This comparative study of mesozooplankton communities in the Tangier (Atlantic) and M’Diq (Mediterranean) regions was carried out in March, May and December 2006 and in May, July and November 2007. In both sectors, the zooplankton is mainly dominated by copepods, which represent 93% in Tangier and 87% in M’Diq, with respectively 85 species in 24 families and 81 divided into 22 families. Spatio-temporal analysis of Copepod specific richness data revealed highest values occurring in both areas during December 2006 and November 2007 with 36 and 30 species respectively. During other seasons, specific richness did not generally exceed 25 species. However, irrespective of area, the composition of the Copepoda population was usually dominated by Paracalanus parvus and Oncaea venusta . In terms of total density, the Atlantic is greater than the Mediterranean sector with a maximum density of 1093 ind.m -3 and 796 ind.m -3 , respectively, recorded in July and May, 2007. The Shannon diversity index was calculated and indicated that the Copepod community is more stable and balanced in the Tangier region compared to the M’Diq area, and in 2007 compared to 2006. Moreover, seasonal variation is more marked in the Atlantic than in the Mediterranean area and in both sectors, the autumn season is characterized by a low productivity but high specific diversity.

Lake Qarun lies in the Egyptian Faiyum Depression and is the modern remnant of a much larger Holocene lake. Variations in water level occurred during the Holocene as a result of palaeoclimate changes and, since ca. 4000 bp, there have been hydrological interventions. Past lake levels have been inferred from the locations of archaeological sites, former beaches and exposed lake sediments, but there is no continuous Holocene palaeolimnogical record for the lake. To explore the potential of this record, three sediment cores (10.4–21.4 m long) were collected from terrestrial locations on the southern margin of the lake in 2008. The basal sections of all three cores consisted of thinly laminated diatom marl sediments overlying coarse sand. The nature of these laminations was investigated in thin sections from two cores (QARU9 and 10). Quantitative very high-resolution diatom analysis revealed seasonal succession patterns of Aulacoseira and Stephanodiscus species within diatom-rich laminae. Elemental microprobe...

Diatom species distributions on remote islands are influenced by both habitat quality and location. In this study diatom distributions and water quality were explored in the Falkland Islands archipelago with reference to island floras elsewhere, using 28 freshwater sites (small ponds, shallow lowland lakes, upland tarns and several streams). Site water chemistries varied from strongly acid to circum-neutral and from low to high conductivity and water-colour. Dissolved ions co-varied with conductivity and varied strongly between sites and ion ratios indicated a strong influence of sea-salt deposition. Canonical Correspondence Analysis of the diatom and environmental data revealed three groups of sites, (1) high water-colour and low pH, (2) low conductivity and low water-colour, and (3) high conductivity and higher pH. Diatom species frequency abundances were most strongly influenced by water conductivity and pH. Diatom assemblages were composed of both cosmopolitan and regionally endemic Subantarctic speci...

Benthic diatoms form a particularly important community in oligotrophic lakes, but factors influencing their distribution are not well known. This study reports the depth distribution of living motile and total diatoms (living plus dead diatoms) on both natural (from sand to fine organic mud) and artificial substrates in an oligotrophic lake. On artificial substrates, motile diatom densities peaked in abundance (24-30 cells · mm(-2) ) between 0.6 and 1.9 m depth; on natural sediment surfaces, motile diatoms were generally more numerous and peaked in abundance (925 cells · mm(-2) ) at 1.3 m depth. Total diatom densities on artificial substrates were highest (1260 valves · mm(-2) ) at 0.6 m depth, with very low values below 3 m depth; on natural sediment surfaces, total diatom abundances were generally much higher (21600 valves · mm(-2) ) at 3 m depth and declined gradually with depth. Significant relationships were found between light and diatom densities on the artificial substrate. Ordination analysis indicated that substrate type significantly correlated with the variation of diatom composition on artificial and natural substrates. Our results suggest that in oligotrophic lakes, light influences benthic diatom abundance, whereas substrate type has more influence on benthic diatom composition.

Stable oxygen and carbon isotopes of freshwater mollusc shells from a sequence of dated palaeolake deposits in the Faiyum Depression, Egypt, provide an outline record of lake development during the Holocene. It is argued that the carbonate O 18 record provides a proxy for climate change and that the isotope changes are driven by variations in monsoon precipitation in Nile headwaters and in local evaporation processes. Shells from sediments dated to ca. 10,000 to 7700 cal BP had low values for oxygen and carbon isotopes indicating higher precipitation in the local area and intensified monsoonal activity, leading to higher Nile flood discharge and flooding of the entire Faiyum Depression. This was followed by a transitional period characterized by marked variability but with precipitation on average less than before. From ca. 6000 to 4300 cal BP, precipitation was decreased until a dramatic reduction in Nile flood discharge occurred late in the fifth millennium BP. This reduction signalled the onset of arid conditions in the Faiyum, partly as a consequence of changes in Nile headwaters that was concomitant with declining lake levels in East Africa. Lake level decline in the Faiyum was further aggravated after 2700 BP as the Nile inflow further weaken and regulation increased.

Because of longer residence times and limited mixing in coastal lagoons, the impacts of anthropogenic nutrient loading to lagoon food webs are often more pronounced than in other coastal ecosystems. For these reasons, many lagoons also provide an excellent environment for the deposition and accumulation of organic matter (OM). Sediment cores were retrieved from three North African lagoons to provide records of recent environmental changes. We measured percentage nitrogen (%N), nitrogen stable isotope values (delta15N), and percentage organic matter (%OM), and we used radiometric dating techniques (210Pb, 137Cs) to examine the evidence for the intensification of upstream agricultural practices in sediment cores from Lake Manzala (Egypt), Ghar El Melh Lagoon (Tunisia), and Lagune de Nador (Morocco). With the exception of one core collected near a sewage outfall, sediments from Lake Manzala clearly reflected the impact of agricultural intensification following completion of the Aswan High Dam and delta barrages in the mid-1960s to early 1970s. Both %N and %OM more than doubled in three Manzala sediment cores, and delta15N values declined from 5 per thousand to1 per thousand. These changes reflect the increasing use of synthetic fertilizers (delta15N approximately 0 per thousand) from the 1960s to the present. Sediments from Ghar El Melh show a similar trend, with %N more than tripling, %OM increasing by 50%, and delta15N declining from 6 per thousand to 2 per thousand since 1965. These changes are consistent with the increasing use of water from a nearby river for crop irrigation and agricultural fertilizer use. Lagune de Nador receives relatively little agricultural drainage water, and core data did not show the same trends as Manzala and Ghar El Melh. Overall, the sediment core data from these systems reflect environmental shifts in the quantity, quality, and isotope signature of the deposited organic matter and confirm the concerns of local scientists and environmental managers that eutrophication has had dramatic impacts on the coastal ecosystems, particularly at the Egyptian and Tunisian sites.

Aim Recent papers have used large palaeolimnological datasets to reveal the biodiversity patterns of aquatic microorganisms. However, scant attention has been paid to the influence of time on these patterns. Where lake surficial sediment samples are used as integrals of diversity, the time interval of each sample varies according to differences in sediment accumulation rates. This paper aims to test the reliability of using lake surface sediments to measure and to compare microbial diversity when the potential influences of the species‐time relationships are taken into account. Location Alpine lakes in Europe. Methods We analysed microorganism (siliceous microalgae) assemblages in three European Alpine lakes using short sediment cores ( 210 Pb-dated) and annual sediment trap samples from 12 UK lakes. The same number of individuals was pooled for each sample 500 times to avoid sampling effort effects and to standardize species diversity estimation. The influence of time on the diversity score was assessed by simulating an increase of time span for surface sediment samples by cumulatively adding in successive sediment core samples (from the most recent to the oldest). We used species richness (S) and the exponential of the bias-corrected Shannon entropy index (exp(Hb-c)) to estimate diversity. Results Increasing the time interval represented by a surficial sediment sample did not affect the diversity results. The estimation of diversity was similar for cumulative and non-cumulative samples. Diversity estimation was only altered in lakes experiencing high community turnover due to strong environmental forcing during the time period spanned by the cumulative sample. Main conclusions The use of surface lake sediments is suitable for estimating the average site diversity of free-living microorganisms. Diversity is integrated in a single sample and species assemblage composition is derived from microbial communities living in distinct lake microhabitats. Species remains, accumulated in a single sample over several years of environmental variability, represent a diversity integral that captures a spatio-temporal component equivalent to the c-diversity measure.

We studied the sedimentology, benthic foraminifera, molluscs, and δ18O and δ13C of Ammonia tepida tests in two late Holocene sediment cores from Lake Qarun (Egypt). The cores, QARU2 (upper section, 8.2 m) and QARU4 (1.4 m), span approximately the past 500 years of sedimentation. Benthic foraminifera first appeared in the upper part of QARU2 at 314 cm depth, ca. AD 1550. This depth marks the beginning of colonization of the lake by foraminifera and indicates a change in lake water salinity, as foraminifera cannot tolerate fresh water. Initially, three species of benthic foraminifera colonized the lake, Ammonia tepida, Cribroelphidium excavatum and Cribrononion incertum. Relative abundance of these species fluctuated throughout cores QARU2 and QARU4 and highest overall faunal diversity occurred at the beginning of the twentieth century. High relative abundances of C. incertum and deformed tests are attributed to periods of greater lakewater salinity. Peaks in both δ18O and δ13C indicate times of higher evaporation and reduced fresh water inflow. Inferred salinity was high around AD 1700 and after AD 1990. Rapid response of climate proxy variables indicates the high sensitivity of Lake Qarun to environmental changes over the past several 100 years. Increases in lakewater Mg concentration during past evaporative events, associated with less fresh water inflow, probably provided conditions suitable for C. incertum to build its white or transparent tests. Gradual decrease of C. incertum, until its disappearance at 100 cm depth ca. AD 1890, indicates a more persistent trend in lake water chemistry. Higher concentrations of dissolved sulphates were the likely cause of this species disappearance. Recent, twentieth-century sediments were deposited under optimal salinity (37‰) for benthic fauna, but further environmental changes are indicated by the decrease or disappearance of several benthic foraminifera and mollusc species. Intermittent hypoxia in the lake’s bottom waters, caused by cultural eutrophication, may account for these most recent changes.

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na+–Cl− brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na+–HCO3− brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.

13 páginas, 8 figuras, 4 tablas., Exploitation of the Athabasca Oil Sands has expanded hugely over the last 40 years. Regional emissions of oxidised sulphur and nitrogen compounds increased rapidly over this period and similar emissions have been linked to lake acidification in other parts of North America and Europe. To determine whether lakes in the region have undergone acidification, 12 lakes within the Regional Municipality of Wood Buffalo and the Caribou Mountains were selected to cover chemical and spatial gradients and sediment cores were obtained for palaeolimnological analyses including radiometric dating, diatom analysis, isotopic analysis of bulk sediment 13C and 15N, and spheroidal carbonaceous particles (SCPs). All lake sediment cores show evidence of industrial contamination based on SCPs, but there is no clear industrial signal in stable isotopes. Most lakes showed changes in diatom assemblages and sediment C:N ratios consistent with nutrient enrichment over various timescales, with potential drivers including climatic change, forest fires and anthropogenic nitrogen deposition. Only one of the 12 lakes investigated showed strong evidence of acidification with a decline in diatom-inferred pH from 6.3 to 5.6 since 1970 linked to increasing relative abundances of the acidophilous diatom species Actinella punctata, Asterionella ralfsii and Fragilariforma polygonata. Analysis of mercury (Hg) in the acidified lake showed increasing sediment fluxes over the last 20 years, a possible indication of industrial contamination. The acidified lake is the smallest of those studied with the shortest residence time, suggesting a limited capacity for neutralisation of acid inputs in catchment soils or by inlake processes., This work was funded by the NOx SOx Management Working Group of the Cumulative Environmental Management Association.

Populations of a fragilarioid diatom from inter-dune lakes of the Badain Jaran Desert (northern China), originally identified and reported under the name Fragilaria sp. cf. famelica , were investigated in detail using light and scanning electron microscopy. The analyses indicate that most of the morphological features of this taxon are identical to Williamsella angusta Graeff, Kociolek & S.R. Rushforth, the type species of the genus Williamsella recently described from Blue Lake warm spring (Utah, USA). The criteria used to separate Williamsella from Fragilaria (i.e. the presence/absence of spines, the colonial formation, the preference for saline vs freshwater habitat, and the coverings of the areolae) are not supported and the genus is refuted. Instead the new combination Fragilaria crenophila comb. nov. is proposed for the Blue Lake species. The taxon from the Badain Jaran desert lakes represents a varietal population that is characterized by shorter valve length and lower stria density than the nominal variety, and is given the name Fragilaria crenophila var. sinensis . A discussion of the taxonomy, ecology and geographical distribution of this taxon is presented and a detailed comparison with Fragilaria asiatica Hustedt, a very similar species described from northern Tibet (China) is made.

To date, little is known about the relative importance of dispersal related versus local factors in shaping microbial metacommunities. A common criticism regarding existing datasets is that the level of taxonomic resolution might be too coarse to reliably assess microbial community structure and study biogeographical patterns. Moreover, few studies have assessed the importance of geographic distance between habitats, which may influence metacommunity dynamics through its effect on dispersal rates. We applied variation partitioning analyses to 15 separate regional datasets on diatoms found in lakes in Eurasia, Africa and Antarctica. These analyses quantified the relative contributions of dispersal related and local factors in determining patterns of taxonomic turnover at the species and at the genus level. In general, results were similar at both taxonomic levels. Local environmental factors accounted for most of the explained variation (median=21%), whereas dispersal related factors were much less important (median of significant fractions=5.5% variation explained) and failed to significantly explain any variation, independent of the environmental variables, in the majority of the datasets. However, the amount of variation explained by dispersal related factors increased with increasing geographic distance and increasing taxonomic resolution. We extrapolated our regional scale observations to the global scale by combining the regional datasets into a global dataset comprising 1039 freshwater lakes from both hemispheres and spanning a geographic distance of over 19 000 km. At this global scale, taxonomic turnover was lowest in highly connected habitats, once environmental factors were partialled out. In common with many other studies of macro-organisms, these analyses showed that both dispersal related and local variables significantly contribute to the structure of global lacustrine diatom communities.