Environmental science and management of coastal lagoons in the Southern Mediterranean Region: key issues revealed by the MELMARINA Project

Lagoons in the heavily populated, semi-arid coastal zone of the Southern Mediterranean Region exemplify the conflict between human utilisation of water and related resources and aquatic ecosystems. Having recognised the requirement to improve understanding of the functioning of the region’s coastal wetlands, the MELMARINA Project undertook integrated hydro-ecological monitoring and modelling within lagoons in Morocco, Tunisia and Egypt. This article highlights some key issues regarding environmental science and management of the region’s coastal lagoons revealed during the course of the project. It stresses the importance of hydrology as a key control upon lagoon functioning and ecosystem dynamics. Hydrological modifications due to water resource management schemes are the cause of many recent changes experienced within lagoons. Linkages between water quality, water availability, human activities and biological characteristics of coastal lagoons are discussed with particular reference to the controls upon vegetation within the MELMARINA lagoons. A series of methodological advances are reviewed which have potential for wider application within coastal lagoons. It is suggested that the use of lagoon sediment for environmental reconstruction can be invaluable, especially when monitoring data are lacking. Recent advances in instrumentation technologies make long-term continuous monitoring more feasible although these approaches can be combined with more traditional site surveys to provide wider spatial coverage at the expense of temporal resolution. Wider spatial coverage can also be achieved through the use of space-borne or aerial remote sensing imagery whilst longer-term trends in site characteristics can be assessed through historical map analyses. Geographical Information Systems, which facilitate the storage and interrogation of large and varied datasets, have enormous potential. Similarly, coupled hydro-ecological models can inform understanding of lagoon functioning and can assess scenarios associated with environmental change or alternative management approaches. The application of integrated, basin-wide approaches to the management of water resources and aquatic ecosystems in the Southern Mediterranean Region is advocated. This includes the application of principles from the EU’s Water Framework Directive. Finally, the need to place management in the context of climate change and associated sea level rise is stressed. Emphasis should be placed on the development of adaptation strategies designed to minimise the effects of these changes. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Application of remote sensing to site characterisation and environmental change analysis of North African coastal lagoons

This article describes the use of satellite imagery for identifying key environmental characteristics within three North African coastal lagoons (Merja Zerga, Morocco; Ghar El Melh, Tunisia and Lake Manzala, Egypt) and for detecting the major environmental changes within these environments. A combination of Landsat MSS, Landsat TM, Landsat ETM+ and ASTER imagery was acquired for the three sites for a period covering the last three decades (1972–2004). Following geometric correction and enhancement, the interpretation of the most recent image acquired for each of the three lagoons provides important insights into their current conditions. For Merja Zerga, these include the distribution of the largest channels which drain extensive inter-tidal mudflats and the two major depositional features associated with sources of freshwater. The distribution of marginal aquatic vegetation is highlighted as is the intensive use of the surrounding landscape for agriculture. Intensive agriculture around Ghar El Melh is also indicated. The influence of the Mejerda River, which was diverted away from the lagoon over 100 years ago, is shown to persist as a residual area of deltaic deposits in shallow water that has been eroded over time. Coastal processes including the direction of the alongshore sediment transport and the influence of engineering work associated with port construction can also be recognised. Within Lake Manzala, vegetated islands divide the lake into a series of sub-basins which can be clearly distinguished. The large influence of human activities within this lake can be identified and include reclamation for agriculture and the conversion of parts of the lake bed for fish farms. The historical images available for the three lagoons provide important insights into decadal scale changes, which have been greatest at Lake Manzala. Since the early 1970s large parts of the lake, in particular in the southwest where the shoreline has migrated northwards, have been reclaimed. Major engineering works, such as the El Salam Canal and road embankments, are shown to have resulted in significant lake change. The distribution of emergent vegetation within the lake has also changed. Classification of images for this lake into open water, vegetation and land enables the quantification of these changes. Between 1973 and 2003, the lake declined in area by approximately 50%. Changes at Merja Zerga over the last three decades include reconfiguration of the marine outlet and the expansion of the internal delta at the end of the Nador Canal. The images of this site clearly demonstrate the intensification of agriculture around the lagoon. The most marked changes evident within the images of Ghar El Melh concern the sand bars that separate the lagoon from the sea. Geomorphological processes operating within the coastal zone have resulted in the straightening of the bars with central sections migrating out towards the sea. Remote sensing is established as a promising application for detecting the quantitative surface cover changes in coastal lagoons and their near landscapes. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Environmental influences on the qualitative and quantitative composition of phytoplankton and zooplankton in North African coastal lagoons

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period extended from July 2003 to September 2004 with the aim of evaluating hydrological and other influences on the structure, composition and space-time development of these communities in each lagoon. Phytoplankton in Merja Zerga showed a quasi-permanent predominance of marine diatoms in the open sea station and in the marine inlet channel. Dinoflagellates were abundant in summer and early autumn in the marine inlet and extended into the central lagoon station. In Ghar El Melh, marine species (especially diatoms and dinoflagellates) dominated despite occasional winter inflows of freshwater. In Lake Manzala, freshwater species generally predominated and the planktonic communities were comparatively very diverse. Chlorophyceae contributed 39% of the total species recorded and diatoms and cyanophyceans were also common; the Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae less so. Zooplankton communities in both Ghar El Melh and Merja Zerga were dominated by marine copepods. Rotifera, Copepoda, Ostracoda, and Cladocera were recorded in both lagoons as were meroplanktonic larvae of Polychaeta, Cirripedia, Mysidacea and Gastropoda and free living nematodes. Ghar El Melh was the more productive of these two lagoons with spring and early summer being the productive seasons. Zooplankton communities in Lake Manzala were generally dominated by rotifers and highest zooplankton abundances occurred in April (2003). Sampling stations near the marine inlets showed the highest diversity and the zooplankton communities showed considerable spatial variation within this large lagoon. The three lagoons represent very different water bodies contrasted strongly in terms of tidal effects and freshwater availability. Yet, there are some similarities in ecosystem structure. Space-time development of the plankton communities was similar especially in Merja Zerga and Ghar El Melh. Species abundances and specific diversities indicated that seasonal changes in salinity and nutrient concentrations were the main influential factors. Lake Manzala was the most productive lagoon and all the three sites supported toxic algal species. Relatively low plankton biomass in Merja Zerga and Ghar El Melh probably resulted from a combination of factors including highly episodic nutrient inputs, light suppression (by turbidity) and nutrient competition with benthic algae. Water quality variables were largely driven by the hydrological regime specific to each lagoon. Nutrient enrichment and, particularly for Lake Manzala, sea level rise threaten the sustainability of the planktonic ecosystems in all three lagoons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

The fish fauna of three North African lagoons: specific inventories,ecological status and production

This paper examines the ecological and biological status of fisheries in three coastal lagoons in the southern Mediterranean region: Merja Zerga in Morocco, Ghar El Melh in Tunisia and Lake Manzala in Egypt. Despite similarities in some ecological characteristics, the three lagoons’ respective fisheries show differences in specific composition, in population structure and in their production both in qualitative and quantitative aspects. Thus, in Merja Zerga and Ghar El Melh the fish fauna shows a marine affinity where grey mullet and eels dominate the fish production. In Lake Manzala the ichthyofauna displays a more freshwater affinity with tilapia the dominant group of species. Otherwise, overall fish production at the three sites is regulated by variations in fishing activities, local environments and seasonal conditions. A decrease in fish production was noted over recent years and this is attributed to deteriorating ecological conditions. A variety of factors are implicated including sea communication problems, reduction of the continental (fresh) water supply and increase of pollution causing eutrophication. In addition, over fishing with a continuing increase of fishing effort units, contributes to fisheries decline. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Sediment distribution and accumulation in lagoons of the Southern Mediterranean Region (the MELMARINA Project) with special reference to environmental change and aquatic ecosystems

Surface sediments and sediment cores were collected from coastal lagoons and lakes located in the Southern Mediterranean Region (SMR) as part of the MELMARINA Project which involved integrated eco-hydrological monitoring and modelling. This study uses surface sediments and sediment cores to infer spatial characteristics and temporal changes at the MELMARINA primary sites, Merja Zerga in Morocco, Ghar El Melh in Tunisia and Lake Manzala in Egypt. In addition, surface sediment sampling was undertaken at Egyptian Lake Bardawil and sediment cores were collected from the Lagune de Nador (Morocco). Sediment distribution patterns are investigated using GIS with georeferenced sample locations to facilitate display and resurvey. Major variations in sedimentary organic matter and, particularly, carbonate content, occur within and between sites. Local landscapes combined with hydrological and biogeochemical processes influence the distributions of sediment bulk components (carbonates, organic material and clastic matter) and molluscan shells and shell debris are an important source of sedimentary carbonate at all three primary sites. Sediment cores were dated using natural (²¹⁰Pb) and artificial (¹³⁷Cs) radionuclides, and sediment accumulation rate changes indicate that sources of sediment supply varied markedly through the twentieth century but have generally diminished after the mid-1960s. Sedimentary siliceous microfossils (diatoms) were generally poorly preserved, but mollusc shell remains were well represented. Sediment chronologies and sediment bulk composition allow discussion of some recent changes in bulk, minerogenic and biogenic sediment accumulation patterns in the SMR lagoons. Sediment accumulation rates also varied between sites and multiple cores from Lake Manzala indicated that rates showed considerable spatial variability. Low-level sediment contamination by fossil fuel combustion particulates and trace metals was demonstrated for Ghar El Melh and Lagune de Nador where Pb and Zn accumulation rates were highest in twentieth century sediment. It is emphasized that sediment quality and quantity have strong influences on lagoon ecosystem function and sedimentation is relevant to hydromorphology and to concepts of ecological quality. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Lack of consistency between the trophic interrelationships of five sparid species in two adjacent central Mediterranean coastal lagoons

Both interspecific and intraspecific inter-lagoon differences, between the central Mediterranean coastal lakes of Fogliano and Caprolace, in the trophic patterns of the examined species Diplodus annularis, Diplodus puntazza, Diplodus sargus, Lithognathus mormyrus and Sparus aurata were revealed by means of correspondence analysis. The most evident inter-lagoon qualitative and quantitative diet changes were observed in S. aurata . Feeding similarities among species were synthesized for each lake by means of multidimensional scaling. Trophic interrelationships among sparid fish were different in the two lagoons, as a direct consequence of diet variations in each species. Such differences are interpreted as possibly reflecting differences in the overall structure of the benthic communities. Different feeding models could be identified, each corresponding to a peculiar adaptive strategy for the consumption of lagoon benthic resources. The use of benthophagous fish feeding habits as a tool for the monitoring of the structure and the dynamics of coastal lagoon communities is discussed.     

Phytoplankton communities of North African wetland lakes: the CASSARINA Project

Seasonal variations in phytoplankton species composition (frequencies) and densities (cell numbers) in nine North African coastal lakes selected in Morocco (Merja Sidi Bou Rhaba, Zerga and Bokka), Tunisia (Chitane, Ichkeul and Korba lakes) and Egypt (Edku, Burullus and Manzala lakes) were investigated during 1998. The main aim was to provide gase-line information about overall phytoplankton diversity and how phytoplanktoncharacteristics differ between these contrasting aquatic systems.Water samples were collected at approximately three monthly intervals and phytoplankton analysis revealed marked seasonal and spatial differences in the quantitative and qualitative composition of the communities at each site. The Egyptian lakes generally had larger crops (Manzala and Burullus had mean crop densities of more than 104 cells ml^–1) but in the western North African sites only Korba and Sidi Bou Rhaba had closely comparable densities. Algae belonging to Bacillariophyceae, Chlorophyceae, Chrysophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae were recorded. Taxa representative of all these algal groups occurred in two lakes (Korba and Manzala) but at the other seven sites only some of the groups were present.The Chlorophyceae was the most dominant group in lakes Burullus, Manzala, Korba and Sidi Bou Rhaba whereas Bacillariophyceae were dominant in lakes Zerga, Bokka and Edku. In Ichkeul and acidic Chitane the Dinophyceae and the Cyanophyceae were the dominant groups, respectively. The maximum percentage of Euglenophyceae occurred in Edku Lake but this group was absent in Sidi Bou Rhaba and Ichkeul. Cyanophyceans were present in significant numbers in all investigated lakes except in Ichkeul. A total of fifty-three genera were recorded, 17 of Chlorophyceae, 18 of Bacillariophyceae, 11 of Cyanophyceae, 3 of Chrysophyceae, 2 of Euglenophyceae and 2 of Dinophyceae. The maximum number of species (34) occurred in Burullus Lake and the minimum (6) in Ichkeul Lake. Only one lake (acidic Chitane) possessed species indicative of oligotrophic conditions. The Nile Delta lakes were the most species diverse sites.The phytoplankton communities of the nine North African lakes were composed entirely of cosmopolitan species but with one new species (Cyclotella choctawatcheeana) was recorded for the region. The data presented provide a contemporary account of the levels of algal diversity present in these sites at the end of the 20th century. The relevance of phytoplankton communities to assessment of lake status and future monitoring studies in the region is emphasised.     

The fate of organic matter sources in coastal environments: a comparison of three Mediterranean lagoons

Trophic processes in coastal lagoons are strongly influenced by freshwater inputs and water exchanges with the sea. In recent years, stable isotope analysis has become a widespread and reliable method for the examination of trophic structure over time and space, also in complex ecosystems such as coastal lagoons. Stable isotopes of carbon and nitrogen were studied in primary producers and consumers to identify organic matter source pools from terrestrial, benthic and pelagic environments and to characterise the trophic structure in three Mediterranean coastal lagoons (Lake Fusaro, the Lake of Sabaudia and Stagnone di Marsala). The results highlighted the negligible importance of terrestrial production to higher trophic levels in all the ecosystems investigated. Consumer dependence on benthic and pelagic organic matter showed high variability: overall macroalgae were at the base of the food web in Lake Fusaro and the Lake of Sabaudia, while mixed sources (seagrass detritus, epiphytes, macroalgae and sedimentary organic matter) appeared to be the major baseline food resource in the Stagnone di Marsala. We have found evidence for significant changes in the trophic structure in these Mediterranean coastal lagoons and such differences may be triggered by differential environmental features (e.g. freshwater inputs and hydrodynamic regime). Guest editors: A. Razinkovas, Z. R. Gasiūnaitė, J. M. Zaldivar & P. Viaroli European Lagoons and their Watersheds: Function and Biodiversity     

Open water zooplankton communities in North African wetland lakes: the CASSARINA Project

Zooplankton (Copepoda, Cladocera, Ostracoda, Rotifera and Diptera larvae) in nine North African lakes was collected from open water areas over twenty months during 1997/99. The results were used to monitor changes in the pelagic micro-invertebrate fauna of these sites with the purpose of exploring diversity structure and regional species occurrences.The studied sites formed three distinct groups based on hydrology and water quality criteria: (i) acid water with no marine connection (Megene Chitane); (ii) alkaline freshwater/brackish with no marine connection (Merja Sidi Bou Rhaba and Merja Bokka); (iii) freshwater/brackish with marine connection (Merja Zerga, Lac de Korba, Garaet El Ichkeul and three Nile Delta lakes). However, cluster analysis of the zooplankton data alone indicated four groups with Korba being separated because of its prevalence of species tolerant of summer hypersalinity.The total regional zooplanktonic species richness found was 88 taxa and these were characterized by species tolerant of widely fluctuating environmental conditions. However, some recorded species were very rare for North African freshwaters (e.g. Alonella excisa, Leydigia quadrangularis and, Ilyocryptus sordidus) and generally indicate favourable environmental conditions of low salinity and temperature. The sites influenced by marine waters generally exhibited slightly lower numbers of species but which generally demonstrate cosmopolitan distributions. Distinct seasonal patterns in species distributions were more similar to those observed in European lakes rather than to those of lower latitudes sites.Zooplankton play a key role in maintaining aquatic ecosystem quality in the North African study lakes and the community distributions described for the late 20th century help set biodiversity base-line data for future studies. If the remaining wetland lakes in this region are to persist as important resources during the 21st century, they will need to be managed in a way that ensures that aquatic diversity is maintained.     

North African wetland lakes: characterization of nine sites included in the CASSARINA Project

Exploitation of land and water resources has increased rapidly in North Africa during the 20th century, paralleling regional population growth. As part of the CASSARINA Project (see Flower, 2001), the environmental status of nine wetland lakes in Morocco, Tunisia, and Egypt was evaluated. All are conservationally important habitats and several are Ramsar Sites (internationally recognized bird reserves) and several support significant fisheries. All are shallow (<2 m in depth) but vary greatly in area.Where available, documentary information on relevant 20th century changes is given. Survey transects for aquatic vegetation were established and used to provide baseline ecological information on the aquatic plant communities during 1997–1999. Unusually, one site (Tunisian Megene Chitane) supported acidophilous vegetation (some taxa being nationally rare). Aquatic macrophytes declined catastrophically at two sites during the 1990s. Merja Bokka was drained in 1998 and, at Garaet El Ichkeul, fringing Phragmites and Scirpus spp. were lost, mainly as a result of salinity changes. Elsewhere, fringing macrophytes remain (extensively so in the Nile Delta lakes) common, despite major land reclamation and water quality problems, or are degraded by grazing (Merja Zerga). Marginal vegetation during 1997/98 changed markedly at Megene Chitane due to water level lowering.Documentary records indicated that throughout the 20th century, reclamation and hydrologic modifications, mainly for agricultural purposes, affected all nine sites. The loss of lake area by reclamation is substantial for the Nile Delta lakes (Edku, Burullus and Manzala). For the western sites, some data indicate increasing salinity in the most recent decade but the Delta lakes have become generally fresher during the 20th century, as supply of Nile water for irrigation increased.Despite intense human disturbance, many of the remaining CASSARINA sites still support regions of high aquatic diversity. Spatial scale monitoring of the larger sites for seasonal and inter-annual changes in open water area and in aquatic plant abundances is a key requirement for integrated environmental change assessment in the 21st century.     

Environmental characteristics,landscape history and pressures on three coastal lagoons in the Southern Mediterranean Region: Merja Zerga (Morocco), Ghar El Melh (Tunisia) and Lake Manzala (Egypt)

Three North African coastal lagoons were selected as primary sites for integrated ecological and hydrological monitoring and modelling as part of the MELMARINA Project (see Flower & Thompson, 2009). The three sites, Merja Zerga (13.2 km², Morocco), Ghar El Melh (35.6 km², Tunisia) and Lake Manzala (c. 700 km², Egypt), are permanent water bodies with at least one well-defined connection with the sea. This article provides an account of each lagoon’s physical characteristics and recent development including the impacts of human activities. The two sites on the Mediterranean (Ghar El Melh and Lake Manzala) are characterised by small tidally driven variations in water level whilst Merga Zerga, on the Atlantic coast, experiences large tidally induced water level variations and so contains large inter-tidal environments. All the three lagoons receive freshwater inflows from their landward margins, varying in magnitude, seasonality and ecological significance. Freshwater inflows from drains strongly influence ecological conditions within Lake Manzala. All the three lagoons have significant biodiversity interest, especially for resident and migratory birds as well as fish, and support local human populations. Each lagoon experienced significant changes during the twentieth century possibly affecting declines in biodiversity value. These largely resulted from agricultural expansion and intensification and include reclamation and hydrological modifications which have both decreased freshwater inflows due to upstream diversions (Merja Zerga and Ghar El Melh) and increased the influx of freshwater through the return of irrigation drainage (Merja Zerga and Lake Manzala). All three sites experienced nutrient enrichment due to agricultural runoff and discharge of domestic wastewater. Industrial waste discharge is a particular, but not exclusive, problem for Lake Manzala. Problems of water quantity and quality will increase through the twenty-first century with increasing demands for water while effects of climate change will enhance freshwater scarcity. Conflicts between human and environmental uses of water will increase and unless improvements in water use efficiency and wastewater treatment can be brought about wetlands including coastal lagoons are likely to suffer further loss and degradation. These problems will be compounded by sea level rise. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Recent environmental change in North African wetland lakes: diatom and other stratigraphic evidence from nine sites in the CASSARINA Project

All nine wetland lakes in the CASSARINA North African suite of sample sites have been disturbed strongly by human activity during the 20th century. Dated lake sediment core were used to provide evidence of the extent of recent environmental change at each site. Sedimentary diatoms at seven sites were useful for inferring salinity change trends during the last century. At two sites preservation problems severely degraded the sedimentary diatom record. Sediment core integrity was otherwise established.Lithostratigraphic measurements indicated some site specific changes in soil erosion and sediment composition but, for the Egyptian Delta lakes, no physical signal synchronous with Aswan High Dam construction was found. Sedimentary diatom assemblages were generally site characteristic and halophilous taxa were common. At two sites planktonic diatoms indicated some recent eutrophication but generally the assemblages were more indicative of salinity changes. Diatom-inferred salinity trends for the seven sites typically indicated that reductions in water salinity occurred sometime during the early or mid 20th century.Rather than climate, hydrological modification of water resources is implicated as the primary driver of salinity changes during most of the 20th century. In the western North African region these modifications were mainly local land drainage and water diversion programmes to alleviate winter flooding and/or promote summer water availability. In the Delta region, the Nile has been intensively exploited since antiquity and intensively so from the late 19th century to release more fresh water for agriculture. Here, diatom records indicate that freshening began well before the Aswan High Dam but salinity fluctuations have tended to diminish during the latter part of the 20th century. A small reversal in the water freshening trend in the 1980/90s was possibly a response to land subsidence/sea-level change or to reduced freshwater supply.Freshwater supply to the sites is generally diminishing as former freshwater surpluses switch to deficit. One site (Merja Bokka, Morocco) became completely dry in 1998 as agriculture encroached and Megene Chitane, the only acid lake in Tunisia, is currently affected by excessive inflow abstraction. At the beginning of the 21st century, eight of the nine CASSARINA sites persist as viable but modified aquatic ecosystems. They nevertheless continue to support valuable aquatic biodiversity, especially in the Delta sites and in Chitane. The modern diatom communities are clearly tolerant of considerable environmental change but the remaining sites are increasingly threatened by major hydrological disturbance. Base-line floristic data for the late 20th century are given but continuous biomonitoring combined with effective management is needed urgently to help conserve North Africa's diminishing natural wetland lake resources.     

First report of the rare tooth fungus Hericium erinaceus in North African temperate forests

Abstract

The rare fungus Hericium erinaceus (Bull.) Pers. was collected from temperate forests in northwestern Tunisia and described for the first time in Africa. In this paper, we report data about the distribution, ecology, morphology and molecular identification of H. erinaceus. Collected data may help expand our knowledge on this critically endangered rare species worldwide.     

Recent environmental change in North African wetland lakes: a baseline study of organochlorine contaminant residues in sediments from nine sites in the CASSARINA Project

Sediment from 9 lakes and lagoons in 3 North African countries was analysed for a suite of organochlorine insecticides and polychlorinated biphenyls (PCBs). Residues of -HCH and pp-DDE were detected in most cores, and radiometric dating of the sediment enabled time profiles to be constructed which are indicative of recent use of the insecticide lindane and previous use of the insecticide DDT in the region. Absolute concentrations of these pesticides were relatively low compared to reported values for other world-wide locations, but exceeded recommended Canadian and Dutch environmental quality standards at several sites. Maximum fluxes of -HCH and pp-DDE (190 and 95 g m^–2 yr^–1, respectively) were relatively high and comparable to some sediments in North America and the United Kingdom. Other organochlorine pesticides including dieldrin were detected at low levels in some samples. Selected PCB congeners were detected at trace levels at 2 sites only, indicating low levels of industrial contamination at the sampling locations. Tropical and sub-tropical regions of the world have been suggested to be contemporary sources of globally distributed organochlorine contaminants. These data are discussed with respect to this hypothesis.     

Experimental taxonomy of Bulinus (Gastropoda: Planorbidae): the West and North African species reconsidered, based upon an electrophoretic study of several enzymes per individual

Horizontal starch gel electrophoresis was used to score mobilities of seven different enzymes in species of Bulinus from North and West Africa. An account of the intra- and inter-population variation observed was given. Based on the data obtained it was suggested that enzymic data should be used as taxonomic characters in parallel with morphological and anatomical characters. It is suggested that enzymic characters could be used to place taxa into synonymy if the data are collected in such a way that one can write up an enzyme profile for the single individual. The nine taxa of Bulinus known to occur in North and West Africa were revised, the taxon B. jousseaumei was synonymized with B. globosus , and the two taxa B. guernei and B. rohlfsi were synonymized with B. truncatus. As a result of the revision only six species could be recognized as valid from the area, these being B. forskalii, B. globosus, B. senegalensis, B. truncatus, B. ugandae and B. umbilicatus. Finally, some enzymic characters are suggested that may be used for a reliable identification of these morphologically very difficult taxa.     

Stenosoma stephenseni sp. n. (Isopoda, Idoteidae), from the southwestern Mediterranean, with a note on the nomenclatural status of Synisoma Collinge, 1917

Recent collections of isopods in Alboran Island and Algeria included several specimens of the species Stenosoma stephensenisp. n. This is the fourteenth species described in the genus Stenosoma Leach, 1814. Examination of two specimens collected during the Danish oceanographic cruises of the Thor (1908-10) close to the Galite Islands, and identified as Stenosoma acuminatum Leach, 1814, revealed that both belong to Stenosoma stephensenisp. n. In light of these findings, the Mediterranean records of Stenosoma acuminatum are revised, and it is proposed that Stenosoma acuminatum is a strictly Atlantic species. An updated diagnosis for the genus Stenosoma is given, together with a key for the identification of its species. The nomenclatural status of the name Synisoma Collinge, 1917 is addressed, and although it is in prevailing usage, it is shown that Stenosoma Leach, 1814 is the valid name of the genus.     

New insights into the ear region anatomy and cranial blood supply of advanced stem Strepsirhini: Evidence from three primate petrosals from the Eocene of Chambi,Tunisia

We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs.     

Dragonfly communities in coastal habitats of Kenya: indication of biotope quality and the need of conservation measures

This study highlights the species diversity of Odonata from coastal forests in southern Kenya, identifying indicator species for certain habitat types and emphasising the importance of conserving the last remaining coastal forest areas. A total of 78 species were recorded from coastal habitats in southern Kenya in this study; five species for the first time in eastern Africa. Dragonfly communities relative to different habitat types from indigenous forest to cultivated landscapes are described and compared. The forest species are often confined to coastal forests of East Africa. They are stenotopic and highly sensitive to disturbance. With increasing habitat disturbance the species richness increases at first, but most of the colonisers are eurytopic species that are common and widely distributed in Africa. The species assemblages between different habitat types in the disturbed landscape are more or less the same; the -diversity is much lower than in different habitat types of the natural coastal landscape. In the end, management implications are briefly discussed.     

ChAnge, Stress, Sustainability and Aquatic ecosystem Resilience In North African wetland lakes during the 20th century: an introduction to integrated biodiversity studies within the CASSARINA Project

The CASSARINA Project is a co-ordinated joint study of recent environmental change in North African wetland lakes. Nine primary sites were selected for detailed study comprising three sites in each of Morocco, Tunisia and Egypt. Multi-disciplinary studies were undertaken by scientists from each of these countries working in co-operation with colleagues in the UK and Norway. The detailed results are presented in a consecutive suite of papers that describe both modern ecosystem attributes and the recent environmental histories of each site. This paper presents an overview of the aims, structure and initial results of the project.Modern site attributes measured were water quality and phytoplankton (Fathi et al., 2001), zooplankton (Ramdani et al., 2001b), fish (Kraïem et al., 2001) and littoral vegetation (Ramdani et al., 2001a). Baseline water quality data showed that one site (Megene Chitane) was acid with low salinity but the others had high alkalinities with varying degrees of brackishness. All the sites tended to be eutrophic and the phytoplankton was mainly dominated by green or blue-green algae. Where fish were present, growth rates were high with marginally highest rates in the Egyptian Delta lakes (Kraïem et al., 2001). Marginal vegetation surveys showed that emergent macrophytes were still extensive only in the Delta lakes (Ramdani et al., 2001a) where they form important refuges and restrict water pollution. In 1998, one Moroccan wetland lake (Merja Bokka) was drained completely for cultivation.Site specific environmental change records for the 20th century period were obtained using palaeolimnological techniques. Sediment core chronologies (Appleby et al., 2001) were based mainly on radio-isotopes (²¹⁰Pb and ¹³⁷Cs). Sedimentary remains of aquatic biota, diatoms, zooplankton, higher plants and benthic animals (Flower et al., 2001; Ramdani et al., 2001c; Birks et al., 2001a) and pollen (Peglar et al., 2001) were investigated (Birks et al., 2001b). Major differences in past species abundances were found and were interpreted in terms relevant to biodiversity and water quality/availability change. Metals and pesticide residues in sediment cores indicated that lake contamination was generally lower than in some European sites but some DDE profiles showed a close correspondence with known usage histories (Peters et al., 2001).Hydrological changes affecting water quality and availability mainly arose from land-use intensification during the 20th century and are shown to be the main driver of biodiversity disturbance at all nine CASSARINA sites. Summarizing floristic and faunistic changes using species richness values indicated that freshening of the Delta lakes during this century generally increased aquatic diversity. Species richness also increased during the final drainage of Bokka but tended to decline in acid Chitane. Modern sampling showed that phytoplankton and epiphytic diatom diversity was higher in the Delta lakes but this was not so for zooplankton. Each biological group reacted differently to environmental disturbance and this lack of concordance makes overall diversity changes difficult to predict.