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We investigated the effects of switching from conventional management to organic management on the abundance and community composition of soil-living oribatid mites in clover fields in an experimental agricultural station at Al-Fayoum, Egypt. The site had two adjacent fields with identical vegetation cover but different management. Fifteen random soil samples were collected monthly from each of three plots per field, from October to March. We characterized the soils with respect to various physicochemical variables as well as fungal community composition, and estimated mite densities through core sampling. Organic fields had a significantly more abundant oribatid community than did conventional fields. Also the abundance of soil fungi was greater in the organically managed field. Organic management promoted common oribatid mite species with a wide ecological amplitude that already had a high abundance where such common species are more responsive to changes in agricultural management. However, some species of mite responded indifferent or negative to the switch from conventional to organic management. Overall, the differences between the two ecological systems were mainly quantitative. Species diversities of both mite and fungal communities did not differ much between the two management systems. Diversity (H′) and equitability (E) of soil oribatid communities were higher in conventional plots than in the organic plots during the first 2 months but indistinguishable thereafter. Our study confirmed that organic management stimulates soil organic matter build-up, with positive effects on both fungal and oribatid mite abundance and possible long-term effects on soil function.

The diversity and abundance of insect pollinators are declining. This decline reduces the potential ecosystem services of pollination for wild and cultivated plants. Specific agri-environment schemes (AES) are subsidised to support and conserve biodiversity in farmlands. In Belgium, the pollinator flower-strips AES, strips of flower-rich hay meadows, has been promoted as a potential scheme to increase pollinator abundance and diversity, even if their effectiveness has not been locally evaluated. The main objective of this research is to assess the capacity of pollinator-strip AES to provide flower-resources to diverse pollinators. During 2 years, we monthly measured the availability of flower resources (pollen and nectar) produced on four flower-strips surrounded by intensive farming in Belgium. We counted and identified insects that visited these flowers, and we constructed the plant–insect interactions networks. The pollinator-strip AES presented a mix of both sown and spontaneous plant species. The ten sown plant species were all present, even after 8 years of strip settings. Three of them, Centaurea jacea, Lotus corniculatus, and Daucus carota were mainly visited for nectar collection, and a spontaneous non-sown species, Trifolium repens, had a key role in providing high-quality pollen to insects. Most of the observed flower-visiting insects belonged to common species of Hymenoptera and Diptera. All are considered highly efficient pollinators. The Belgian pollinator flower-strips are effective AES that provide flower resources to pollinators, mainly during summer and support pollination services. Nevertheless, spring and autumn flower resources remain poor and could reduce the strips’ effectiveness for supporting long-term insect diversity.

Facilitation (positive inter-specific interaction) plays an important role in promoting succession in harsh environments. To examine whether tussocks facilitate the establishment of other species, after peat mining, investigations were carried out in a formerly Sphagnum-dominated wetland (Sarobetsu mire, northern Japan). Two tussock-forming species, Carex middendorffii and Eriophorum vaginatum, have established in sparsely vegetated areas, with a dry ground surface, since peat extraction ended. The following factors were examined, in three microhabitats created by tussocks (center = raised tussock center, edge = tussock edge covered with litter, and flat = flat areas without tussocks): (1) relationships between tussock microhabitats and plant distributions, and (2) the effects of tussocks on survival, growth, flowering and seed immigration of common species. Two (1 × 10 m) plots were established, in each of three sparsely vegetated sites, in September 2005. Tussocks were mapped in each plot, and species, location, flowering, growth stage (seedling, juvenile and fertile) and size of all plants were recorded, during snow-free periods from September 2005 to September 2006. Seed traps were used to investigate seed dispersal from June to October 2006. Four native species, Drosera rotundifolia, Lobelia sessilifolia, Moliniopsis japonica, Solidago virgaurea, and an exotic species, Hypochaeris radicata, were most common. During seedling and juvenile stages, these species were distributed more densely at the tussock edge than in the flat areas, but were less common at the center. H. radicata had a higher survival rate at the edge than in the flat during the winter. The annual growth of H. radicata, L. sessilifolia and S. virgaurea was higher at the edge. Seed traps detected that D. rotundifolia seeds accumulate more at the edge. In conclusion, tussocks facilitated plant establishment in the edge microhabitat by providing litter cover, enhancing seed accumulation, germination and survival, and thus promoted revegetation. However, Sphagnum mosses have not established in the study sites, and the vegetation differs strongly from the areas where no peat mining had taken place.

Urban ecosystems are complex social-ecological systems with important functions. These man-made ecosystems have certain areas with high biological diversity, including both remnant species and species purposefully or unintentionally introduced by human actions. There can be important habitats and valuable corridors for both common and less common species within the urban sprawl. The main aim of this study is to respond to the call for integrative research by studying relationships between the anthropogenic activities and urban biodiversity of the cities from the southern part of Rajasthan, India. We observed that the local population was interested in biodiversity, especially phenological events, and benefited from it by getting aesthetic pleasure and information on seasonal changes. The cities, such as Udaipur have an artificially developed diversified habitat within urban limits which provides shelter and protection to a variety of flora and fauna species. Urban areas are often rich in species, particularly vascular plants and many groups of animals, especially birds. Further, urban green spaces in the form of artificial parks and agricultural fields have the diversity of flora, whereas artificial lakes are the sites of wetland species. The most eye-catching faunal group of birds was used to understand the importance of biodiversity for Udaipur. Bird diversity and abundance are indicators of the condition of watershed habitats, both terrestrial and wetland. The role of urban areas in functions, such as the provision of ecosystem services will largely be determined by patterns of biodiversity within that area. To keep these biological indicators healthy, watershed conditions should be managed to encourage bird survival and reproduction. Further, to support an integrative approach in urban green planning, both ecological and social research has to be incorporated in the planning process.

Diatoms, or their plastids, are symbionts of four different families of foraminifera. Evidence suggests that the evolution of these families was driven by their symbiotic relationships. All hosts are many times larger than their ancestors, have complex subcompartmentalization, and have multiple nuclei and internal organelles (e.g., Golgi, mitochondria). The diatom symbionts and the captured plastids are photosynthetically active. Symbiotic diatoms have a 104 kDa glycoprotein epitope on their surfaces that is recognized by receptors on the host’s reticulopodia. Less than two dozen species of diatoms are involved in the phenomenon. All are small (≤10 μm). Nitzschia frustulum var. symbiotica is the most common species. This species along with two other species of Nitzschia, N. laevis Hustedt and N. panduriformis var. continua Grunow in Cleve and Grunow, Nanofrustulum shiloi (Lee, Reimer, and McEnery), Amphora roettgerii Lee and Reimer, and Amphora erezii Reimer and Lee, were isolated from over 75% of the associations. Several diatom species have unusual mechanisms for size regeneration. Host homogenate experiments suggest that there are signals that cause the symbiotic diatoms not to form frustules and to release their photosynthetates. Benefits to the holobiont and to each symbiont are discussed.

Two species of tortoises are known from Pliocene sites on the Eyasi Plateau, including Laetoli. The most common species is a medium-sized tortoise, Stigmochelys brachygularis, which is well represented in the Laetolil Beds (∼3.6–4.4 Ma) and Upper Ndolanya Beds (∼2.66 Ma). The giant tortoise, “Geochelone” laetoliensis, is known only from the Laetolil Beds, and is much less common than S. brachygularis. Stigmochelys brachygularis is represented by a number of relatively complete and partial shells, as well as numerous isolated and associated shell fragments, some postcranial remains and eggs. It is generally similar in size and overall morphology to the extant leopard tortoise, S. pardalis, but a number of features serve to distinguish the two species. Stigmochelys brachygularis and S. pardalis are inferred to be closely related, and are most likely sister taxa that represent time-successive species of a single lineage. The age structure of the fossil sample, in conjunction with evidence of carnivore damage on the shells, indicates that S. brachygularis was subject to relatively high levels of predation in comparison with modern-day S. pardalis. If S. brachygularis is presumed to have been ecologically similar to modern S. pardalis, it would have been capable of living in a wide range of habitats from semi-desert and savanna to open woodland. The material attributed to “Geochelone” laetoliensis is more fragmentary, and as a consequence it is not possible to determine its precise phylogenetic or taxonomic relationships. However, it likely represents a distinct genus, possibly with affinities to Astrochelys from Madagascar. A more thorough assessment of the relationships of “G.” laetoliensis with Miocene and Pliocene giant tortoises from Africa and with extant genera will have to await the recovery of more complete material from Laetoli. Giant tortoises, such as “G.” laetoliensis, became extinct on mainland Africa during the late Pliocene, possibly associated with the appearance of early Homo and stone tool using behaviors at 2.6 Ma.

New finds from Laetoli have allowed a more detailed assessment of the taxonomy and paleobiology of the fossil ­cercopithecids. Most of the specimens consist of isolated teeth, jaw fragments and postcranial bones from the Upper Laetolil Beds (∼3.5–3.8 Ma), but four specimens are known from the Upper Ndolanya Beds (∼2.66 Ma) and a proximal humerus has been recovered from the Lower Laetolil Beds (∼3.8–4.3 Ma). Four species are represented: Parapapio ado, Papionini gen. et sp. indet., cf. Rhinocolobus sp., and Cercopithecoides sp. Parapapio ado is the most common species. Based on dental size and proportions and facial morphology, Pp. ado can be distinguished from all other species of Parapapio. The postcranial specimens attributed to Pp. ado indicate that it was a slender and agile semi-terrestrial monkey. A few isolated teeth represent a second species of papionin, larger in dental size than Pp. ado. Due to the paucity of the material, the taxon is left unassigned at the genus and species level. A distal humerus attributed to this taxon indicates that it was large terrestrial cercopithecid. The most common species of colobine is referred to cf. Rhinocolobus sp., based on its overall similarities to Rhinocolobus turkanaensis. The material can be distinguished from all fossil colobine species previously recognized from Africa, but without more complete cranial specimens it is not possible to diagnose a new taxon. From the postcranial material it can be inferred that it was generally adapted for arboreal quadrupedalism. The somewhat smaller species of colobine represents a previously undescribed species of Cercopithecoides. The postcranial specimens attributed to this taxon indicate that it was fully arboreal. Analysis of the distribution of the Laetoli cercopithecids provides provisional evidence of spatial patterning and temporal trends. For example, the dentition of Parapapio exhibits a trend to increase in size during the course of the Upper Laetolil Beds. As at other late Miocene and early Pliocene localities older than 3.5 Ma, the Laetoli cercopithecid community is characterized by the absence of Theropithecus and the relatively large proportion of colobines. After 3.5 Ma Theropithecus becomes the dominant cercopithecid at all East African ­localities, and the proportion of colobines declines accordingly.

The genus Ogyris, commonly known as the ‘Azures’ contains some of the most spectacular and ecologically intriguing lycaenids in the region (Fig. 7.1), and most species – some of considerable conservation interest – occur very patchily in the landscape. Even the more common species tend to be highly localised with widely separated populations, but some distribution records are obscured by uncertain taxonomy. Some of the more common species are rather variable, with several named subspecies, and some rarer taxa are also taxonomically complex and their integrity, in some cases, ambiguous. In consequence, some historical records of their incidence are also ambiguous, and differences between some named subspecies are small. As one pertinent example, detailed discussion of the nomenclature of a scarce taxon of conservation interest, O. halmaturia, has led to reinstatement of this name (Grund 2010) soon after it was dismissed in favour of O. waterhouseri by Braby and Douglas (2008).

Eleven species of the genus Cosmochthonius have been recorded in the eastern Mediterranean and in some parts of the former Soviet Union. Five of these species [C. reticulatus Grandjean, C. foliatus Subias, C. lanatus (Michael), C. semifoveolatus Subias, and C. asiaticus Gordeeva] have been found in the western Mediterranean as well, whereas the other six species (C. ugamaensis Gordeeva, C. zanini Niemi & Gordeeva, C. macrosetosus Ayyildiz & Luxton, C. tenuisetosus Gordeeva, C. taurus Niemi, Gordeeva & Ayyildiz, and C. ponticus Gordeeva) can be considered to be endemic. The most common species in the eastern Mediterranean was C. reticulatus. It was found on the Mediterranean islands (Crete, Cyprus, Rhodes, Symi-Rhodes, and Lesvos) and in the coastal zone of Turkey and the Ukraine. In contrast to this distribution, the species C. foliatus seemed to be absent from these islands and from the coastal zone of Turkey, but it regularly occurred in the southern and southeastern Crimea, Ukraine. The exact locations of the species found in the eastern region are documented here, and the habitus of eight species is presentedin the form of SEM micrographs.

Ten species of Sargassum (Sargassaceae, Phaeophyceae) were found along the Gulf of Thailand. Morphological characteristics of Sargassum baccularia (Mertens) C.A. Agardh, S. binderi Sonder, S. cinereum J.G. Agardh, S.crassifolium J.G. Agardh, S. longifructum Tseng et Lu, S. oligocystum Montagne, S. polycystum C.A. Agardh, S. siliquosum J.G. Agardh, S. swartzii (Turner) C.A. Agardh and one unidentified species were examined and are described in detail. The most common species were S. polycystum distributed widely in almost all the study sites, S. crassifolium restricted to Prachuap Khirikhan Province, S. longifructum restricted to Chumphon Province, S. siliquosum restricted to Surat Thani Province and one unidentified species restricted to Songkhla Province. Three species (S. cinereum, S. longifructum and S. swartzii) are new records for the algal flora of Thailand. Five species (S. baccularia, S. cinereum, S. longifructum, S. polycystum and the unidentified species) belong to the section Zygocarpicae (J.G. Agardh) Setchell.

In spite of their potential use as indicators of both present and past environmental conditions, little is known about the diatom communities in the many small water bodies at high altitudes in New Zealand. We sampled benthic diatoms at 20 sites in a typical subalpine mire pool/tarn complex near Arthur’s Pass in South Island, New Zealand in the austral spring 2001. The aims were to characterise the diatom communities, including identification of a possible endemic component, and to investigate relationships with environmental variables. The community at genus level was consistent with the peat-bog diatom flora reported from elsewhere except for the common occurrence of the Tasmania/New Zealand endemic genus Eunophora. At the species level, 27 of the 52 most common taxa appear to correspond to known species from the Northern Hemisphere and are therefore presumed to be cosmopolitan in their distribution. Just two taxa are known from the Southern Hemisphere only, however identification of the remaining common species proved problematic. Analysis using the BIO-ENV procedure of the PRIMER computer program confirmed an expected strong association between diatom community composition and pH, with water conductivity and gilvin also important. Weighted averaging regression and cross-validation using C2 software enabled selection of four diatom species as potentially sensitive indicators of certain pH levels. Neither species of Eunophora showed a strong preference for pH or for any of the other environmental variables measured, indicating that other factors are determining their distributions. The strength of the species–environment relationships found in this small survey suggests good potential for monitoring current conditions and for palaeoecological applications. Extension of the dataset with information from other alpine/subalpine areas is desirable, as is the compilation of a regional diatom identification guide for these habitats.

Hong Kong rocky shores are dominated by cyanobacterial biofilms composed of a diversity of species. Thirteen common species, belonging to seven genera, were isolated in pure culture in MN+ and MN− media under defined growth conditions from a semi-exposed shore in Hong Kong. The nutritional values (i.e., protein, carbohydrate and calorific value) of these 13 species were determined. All species showed high nutritional quality in terms of protein, carbohydrate and calorific value, however, overall nutritional value varied between the species. Species of Spirulina and Phormidium were most nutritious (highest nutritional values) whereas species of Calothrix and Lyngbya were the least nutritious. Microphagous molluscan grazer density and diversity were relatively high at the study site, despite the seemingly low biomass (as assessed by chlorophyll a concentration) of the biofilm. It is suggested that the high nutritional quality of cyanobacteria, together with their fast turnover rates can support high levels of secondary production (biomass of grazers). The high nutritional quality of cyanobacteria on tropical, cyanobacteria-dominated, rocky shores is therefore of great importance in the benthic food web.

Quantitative samples were collected from Lake Atnsjoen five times per year in the growth seasons 1990-2000. The samples were analysed for variation in the phytoplankton composition, and the total volume and volume of the main groups of algae were calculated. Lake Atnsjoen is a large, deep and unregulated lake with a surface area of 4.8 km2 and a maximum depth of 80.2 m. It is a nutrient-poor, oligotrophic lake with a maximum phytoplankton volume varying between 125-393 mm3/m3 in the years 1990-2000. The phytoplankton community is dominated by species of the groups Chrysophyceae and Cryptophyceae. The chrysophytes dominate the phytoplankton in the early part of the growth season (May—June) while the cryptophytes increase throughout the season and dominate in the autumn. Among the chrysophytes different species of chrysomonads were most frequent together with common species of the genus Dinobryon like D. borgei, D. cylindricum var. alpinum and D. crenulatum. A total of 22 species or taxa of chrysophytes were recorded in the samples. Common among the cryptomonads were several species of the genus Cryptomonas. Most important quantitatively, however, were Rhodomonas lacustris and Katablepharis ovalis. The succesion of the phytoplankton throughout the growth season was similar from year to year in quantitative as well as qualitative terms, but some changes were recorded after the great flood in 1995. Canonical Correspondence Analysis (CCA) shows a slight, but significant, phytoplankton community change over the succeeding years.

In this pilot study, it is outlined how presence/absence (P/A) registrations on sample plots can be used for assessing plant cover changes. With a simple Poisson assumption regarding the spatial distribution of plants, it is shown how vegetation cover can be estimated from mere registrations of whether plants occur on plots or not. The motivation for this approach is that many studies have shown that vegetation cover assessment is prone to surveyor-induced bias, while P/A sampling of vegetation is believed to be less susceptible to this. On the other hand, it is less intuitive how to interpret changes in P/A data than in vegetation cover data. Based on model relationships between P/A registrations and cover, the importance of selecting adequate plot sizes for P/A surveys was illustrated in this study. For example, if large plots are used, major changes in vegetation cover may occur for a common species before this is noted in P/A data.

In 2000, a field study in two shallow, polytrophic lakes (Langer See and Melangsee) in eastern Germany revealed an equilibrium state assemblage of Cyanoprokaryota in late summer. During 4 successive weeks in Langer See Planktothrix agardhii (Gom.) Anagn. et Kom., Aphanizomenon gracile (Lemmerm.) Lemmerm. and Pseudanabaena limnetica Lemmerm. were more than 80% of the standing biomass of phytoplankton, and their cumulative biovolume was around 33 mm3 l−1 ((±3.2 SD). In Melangsee, the very small Limnothrix species L. amphigranulata (Van Goor) Meffert was the most common species, accompanied by Pseudanabaena limnetica andPlanktothrix agardhii. For 3 weeks, their cumulative biovolume was about 23 mm3 l−1 ((±3.4 SD), which represented 75 – 82% of total biovolume. The dominant species all belong to the functional group S N defined by Reynolds (1997), except for A. gracile, which we suggest to be included in group S N . In both lakes mean light intensities ranged between 2.2 and 8.3 E m−2 d−1. Overall species spectra were very similar in both lakes, but dominance by Limnothrix and by Planktothrix in the respective lakes is observed repeatedly. The success of these species is discussed in the context of the habitat properties in August/September. Summer mixing events represented no disturbances in the sense of Connell (1978), since they do not interrupt the species dominance. More frequent mixing events and higher concentrations of dissolved nitrogen occurred in Langer See than in the more shallow, but wind protected Melangsee. In Langer See light deficient conditions were intensified by an increasing biomass of P. agardhii, and this species probably benefited from nutrient input by more frequent resuspension. The light deficiency also affected the diversity, expressed as Shannon—Wiener Index (H), which was reduced more in lake Langer See (H = 0.51) than in Melangsee (0.74) during steady state periods. Recognizing the important effects of mixing, we suggest an additional variable to describe habitat properties: the number of full mixing days as a proportion of total days of observation should help to discriminate between shallow habitats with intermittent mixing events, and those with more regularly mixing in summer period.

A new species of Pseudanabaena (Cyanoprokaryota, Oscillatoriales) from the plankton of North American large lakes is documented, with ecological and distributional data. This taxon differs from previously described Pseudanabaena species with respect to a characteristic undulating and coiling filament structure. Pseudanabaena contorta spec. nova appears to be specific to large North American Great Lakes with a drainage basin that is not totally Precambrian shield. Recently, it has been found as a consistent but minor component of the planktic cyanoprokaryote populations during the spring and summer months in Lake Superior and Lake Ontario. Comparisons are made with other common species of this genus as well as another undulating morphotype of the genus Glaucospira, that could possibly result in confusion, found in other large Alberta and northern Saskatchewan lakes.

Seasonality of phytal harpacticoids was studied in a tidal pool in the lower rocky intertidal in south-western Iceland. Samples of the red alga Chondrus crispus were taken monthly from January 1999 to January 2000. Multidimensional scaling ordination showed a clear seasonal pattern in phytal species composition and abundance of individual species. Of more than 70 species recorded, Zaus spinatus accounted for one third of the total abundance. Many species were found only sporadically and analysis of the data was confined primarily to the eleven most common species (Zaus spinatus, Ectinosoma spp., Tisbe spp., Ameira longipes, Mesochra sp. 2 and Mesochra sp. 1, Dactylopusia vulgaris, Amphiascoides debilis, Amphiascus sp. 1, Parastenhelia spinosa and Amphiascus minutus). Four showed no significant variation in total abundance through the year, while the remainder had more or less pronounced peaks in summer. Most species (on which data was sufficient) had a prolonged (≥6 months) to a continuous breeding season, as indicated by the presence of ovigerous females. This contrasts with most shallow-water temperate and subarctic invertebrates which appear to have more restricted breeding seasons. Our results extend to higher latitudes the general conclusion that many temperate phytal harpacticoids have a long, often continuous, breeding season. The reasons for this are unclear but, presumably, involve access to continuous food supply. There is strong evidence that variations in abundance of several species in the tidal pool were not due only to recruitment, but also to migration to the pool in summer and emigration in autumn.

A number of recent review articles on ectomycorrhizal (ECM) fungal community diversity have highlighted the unprecedented increase in the number of publications on this ecologically important but neglected area. The general features of these species-rich, highly dynamic and complex communities have been comprehensively covered but one aspect crucial to our assessment of diversity, namely the sampling of ECM communities has received less attention. This is a complex issue with two principal components, the physical sampling strategy employed and the life cycle traits of the ECM fungi being examined. Combined, these two components provide the image that we perceive as ECM diversity. This contribution will focus primarily on the former of these components using a recent study from a pine forest in central Sweden to highlight some sampling problems and also to discuss some features common to ECM communities. The two commonly used elements of diversity, species richness and community evenness, present rather different problems in the assessment of ECM diversity. The applicability of using current measures of abundance (number or percentage of root tips colonised) to determine community evenness is discussed in relation to our lack of knowledge on the size of individual genets of ECM fungi. The inherent structure of most ECM communities, with a few common species and a large number of rare species, severely limits our ability to accurately assess species richness. A discussion of theoretical detection limits is included that demonstrates the importance of the sampling effort (no. of samples or tips) involved in assessing species richness. Species area abundance plots are also discussed in this context. It is suggested that sampling strategy (bulk samples versus multiple collections of single tips) may have important consequences when sampling from communities where root tip densities differ. Finally, the need for studies of the spatial distribution of ECM on roots in relation to small-scale soil heterogeneity and of the temporal aspects of ECM community dynamics is raised.

Rhizoglyphus robini Claparede and R. echinopus Fumouze et Robin are the most common species of the genus. They are distinguished on the basis of the Sci setae length (short in R. robini, long in R. echinopus) and the shape of the penal base, but these diagnostic features may vary within species, and both species were reported from the same habitats. We carried out experimental hybridization of R. robini and R. echinopus in reciprocal crosses to see if they are reproductively isolated. The results showed strong genetic incompatibility in the parental generation, more pronounced in R. robini females mated to R. echinopus males (7% fecund) than in R. echinopus females mated to R. robini males (20% fecund). We recorded complete sterility in F1 hybrids, confirming the reproductive isolation of these species.

Common woody species growing on tree islands in the Water Conservation Areas of South Florida include redbay, sweetbay, coastal-plain willow, wax myrtle, dahoon holly, cocoplum, pond-apple, red maple, cypress, gumbo-limbo, strangler fig and buttonbush. Very little is known about the flooding tolerance of most of these species. In this paper, we review flooding impact studies, describe the most common species and discuss two methods that might be used to examine woody plant growth response to water level fluctuations. Although tree coring has been used effectively in many areas, the general lack of discernible rings and poor quality rings observed in these species makes this method of questionable use. Dendrometer bands, however, work well in any environment with any species and are recommended for further studies on tree islands.

Information on the density and diversity of zooplankton from drinking water reservoirs in Mexico is meagre. This is important not only from the point of view of lake management but also for providing clean drinking water for human populations. In the present work, we provide quantitative information on the seasonal variations of zooplankton and selected physico-chemical variables from Valle de Bravo, a large man-made reservoir in the State of Mexico. Based on the nutrient data, this reservoir can be regarded as mesotrophic. However, we found a high density of phytoplankton. Among Cyanophyceae, Anabaena, Microcystis, Nostoc and Oscillatoria were encountered, particularly during the warmer months. Microcystis blooms were observed from June to September. Diatoms dominated the phytoplankton during the remaining months of the year. Among zooplankton, Rotifera comprised the highest number of species. The most common species occurring throughout the year were Keratella chochlearis, Polyarthra vulgaris, Trichocerca capucina, Trichocerca similis, Asplanchna priodonta and Synchaeta pectinata. The highest abundance of K. cochlearis was observed in May at site 5 (340 ind 1−1 ). P. vulgaris occurred in high numbers throughout the year. Both Trichocerca capucina and T. similis were encountered in low numbers (mean annual average: 10 ind 1−1). Among the crustacean zooplankton, Bosmina longirostris occurred in higher numbers (up to 105 ind 1−1) regardless of the time of the year. Copepods were predominantly from the genera Mesocyclops and Megacylops; calanoids were rare. Naupliar stages were dominant during winter months (up to 670 ind 1−1). These results have been discussed from the point of view of Microcystis control in water bodies.

We compared six biochemical measures of nutritional condition: citrate synthase activity (CS), malate and lactate dehydrogenase activity (MDH and LDH), RNA:DNA ratio, and percent body protein and lipid. Adult females of five species of calanoid copepod (Calanoides acutus, Calanus propinquus, Metridia gerlachei, Rhincalanus gigas and Paraeuchaeta antarctica) were collected in the marginal ice zone of the northwestern Weddell Sea at the time of the annual phytoplankton bloom that occurs in association with the receding ice edge during austral spring. Three zones within the marginal ice zone were sampled: heavy-ice-cover pre-bloom, ice-edge bloom and low-ice-cover post-bloom. Lipid generally increased greatly from ice-covered to open water zones, and its importance in the life of polar copepods cannot be overstated. Increases in protein from ice-covered to open water were also observed, but were of less significance. Each species exhibited significant changes in at least one enzyme activity level. Citrate synthase activity in C. acutus, C. propinquus and R. gigas, all herbivores, increased between pre-and post-bloom stations. C. propinquus and M. gerlachei, which feed during winter, had large increases in LDH activity between pre- and post-bloom stations. Rhincalanus gigas and P. antarctica, the two largest species studied, showed variations in MDH activity, with peak enzyme activity occurring in post-bloom stations. RNA:DNA ratio did not change in any species. The effects of size, shipboard handling and freezer storage were easily corrected statistically, and did not alter any conclusions. The patterns observed in copepod nutrition at the Antarctic ice edge were consistent with existing models of life history for each species. The observations reported here, in conjunction with previously reported data, suggested that measurement of metabolic enzyme activity, especially in concert with lipid, enables estimation of nutritional condition in adult copepods. Additional studies comparing metabolic activity and ecology of common species should yield more information on the ecology of rarer species.

In a relatively small area of 60 km2 which corresponds to the basin of the presently drained Lake Hula and its swamps (Upper Jordan Valley), 22 species of Cyclopoida are on record, with two more species reported in the pre-drainage times. The basin of Lake Hula is the southernmost enclave of permanent fresh waters in the Levant Province of Southwest Asia. Lacustrine and swamp environments existed in the area uninterruptedly for at least 700 000 years. A partial restoration project created a new lake. The basin is situated right in the middle of a main bird migration route. The fact that no less than 15 species were recorded from a set of small artificial and isolated experimental ponds seems to indicate that migrating birds and stocks of resting eggs are to account for this high diversity. Cyclops vicinus, Mesocyclops arcanus and Eucyclops serrulatus are the most common species. The success of the restoration is discussed.

Patches of vegetation of six common species growing on Leonie Island (67°35′ S, 68°20′ W), Antarctic Peninsula region were covered with either UV-B transparent perspex screens or UV-B absorbing screens. Uncovered plots served as a control. Temperature and relative humidity were monitored during the austral summer under and outside the screens. The mean effective PSII quantum efficiency showed significant differences among the species, but not between the UV-B treatments. It was concluded that the temperature and the moisture status of the vegetation obscured any possible influence of UV-B treatment on the tteffective PSII quantum efficiency. he usefulness of various UV-B exclusion and supplementation methods used to study the influence of UV-B in the field is discussed.

During a period of 10 years, from 1988 to 1997, we monitored the species composition in dry grasslands of high species richness at experimental sites in the ‘lower montane zone’ of the southern Alps in Switzerland. We examined responses of the abundant herb species to stochastic factors, abandoning, and mowing after abandonment. Although mowing was regularly continued at one meadow site half of the common species showed clear positive or negative frequency trends which are climatically explained. Succession after abandonment resulted in dominance of Brachypodium pinnatum and reduction in the number of species at two meadow sites. This process was also affected by spatial heterogeneity and stochastic factors. Resumed mowing in a meadow after 20 years of abandonment resulted in slow shifts of the species composition. Brachypodium dominance was unchanged and the establishment success of ‘meadow species’ was poor. This was not due to unfavourable site conditions but to limited availability of seeds. Seed limitation plays an important role in the dynamics of grasslands. From a conservation perspective this implies that maintenance of still existing meadows of high species richness should be given high priority. A better understanding of regeneration processes and a better knowledge of the regenerative characteristics of grassland herbs would be essential for making better predictions about responses of plant species to altered environmental factors in grasslands.

For over 10 years, the midwater ecology group at MBARl has compiled video and accompanying physical data with the ROV Ventana operating in mesopelagic depths of Monterey Bay, CA in order to elucidate patterns in midwater ecology. Two El Nino events have occurred during this time period, in 1991–92 and in 1997–98. The oceanographic metric of spiciness combines temperature and salinity data into one sensitive measurement. Although temperature and salinity measurements alone revealed no clear patterns, clear signals of spiciness were observed that corresponded to water mass intrusions into the deep waters of the bay during the two EI Nino events. During these events, some seldom-seen species were observed in high numbers in the midwater, while historically common species became rare. During non-El Nino years, the leptomedusa Mitrocoma cellularia (A. Agassiz, 1865) was common in the surface waters (0–50 m) of Monterey Bay, but it was not abundant at depth, while the trachymedusa Colobonema sericeum Vanhoffen, 1902 was found in relatively high numbers at mesopelagic depths. During the last two El Nino events, M. cellularia was observed in higher numbers at mesopelagic depths, whereas C. sericeum was scarce. M. cellularia was found in a wider range of temperatures, salinities, and dissolved oxygen values than was C. sericeum. Transport and tolerance hypotheses are proposed to explain differences in the presence and numerical density of the medusae.

Many genera and species of plant parasitic nematodes are associated with coffee. These cause great financial losses to the coffee farmers. Among these pathogens, root-knot nematodes (Meloidogyne sp.) are the most abundant group (Table 1) and the most common species are M. exigua, M. incognita and M. coffeicola.

Spartina patens (Gramineae) is an American coastal grass which grows in a wide range of coastal habitats in its native area. After it was discovered in some Galician wetlands two years ago, we undertook a regional survey whose preliminary results reveal that this grass is actually a rather common species in Southwestern Galicia, being present in several coastal habitats also. Nevertheless, it is in saltmarshes where it seems to compete more successfully, invading rush communities that have been traditionally harvested for cattle bedding. In many estuaries, it tends to form dense monospecific stands and could become a serious threat to high marsh plant diversity. In order to evaluate the impact of S. patens as an invasive weed in saltmarshes, we have performed a transect study, which seems to indicate that S. patens establishes preferentially in the upper marsh (but reaching higher coverages in the uppermost part of its altitudinal rank), where it has a significant negative effect on species diversity as well as on total cover of other species.

A study was conducted on the overwintering of predatory mites on hazelnut at two different altitudes (500 and 1000 m a.s.1.). The most common species encountered during two successive winters were Kampimodromus aberrans, Typhlodromus intercalaris and Typhlodromus cryptus. At both altitudes, all three species overwintered predominantly as non-ovipositing female. At 500 m a.s.l., the first young stages of K. aberrans appeared in the second half of April, while no young stages were found until May at 1000 m a.s.l. A few males and young stages of T. intercalaris were found at 500 m a.s.1., no young stages were found at 1000 m a.s.l. Compared to T. intercalaris, more males and young stages of T. cryptus could be observed at 500 m a.s.l. — at 1000 m a.s.l., only a few males were collected and young stages were completely absent. The calyces of the insemination apparatus of overwintering females of the three species were usually found empty. Ten percent of the females at 500 m a.s.l. showed remnants of spermatophores and only few females had an intact spermatophore inside. At the higher altitude the situation was similar, but the number of females containing spermatophores or their remnants was smaller.

Comparative studies of the biological traits of taxonomically related rare and common species are scarce. The past couple of decades, however, have seen a growing number of attempts to rectify this situation. In the main (though not exclusively), these studies have concerned small numbers of species, in one or a few genera, and have examined at most a few features of their biologies. Nonetheless, some potentially important regularities have begun to emerge. In this chapter we will consider several of these patterns and review the evidence for them. Discussion of possible mechanisms and related theory is left to later chapters in the book (many of the studies cited here will thus make later reappearances).

The morphology of gonads and development of offspring of the scallop Mizuhopecten yessoensis sampled from six stations in Peter the Great Bay (Sea of Japan) were studied. The retardation of gametogenesis, oocytes resorption, autolysis of spermatozoa and their phagocytosis were observed in the gonads of the scallops from polluted sites. The number of hermaphrodites was about 6% against 0.3–0.4% in the scallop populations from clean areas. In the offspring development, a decrease in fertilisation success, diminution in percent of normal trochophores, D-veligers, veligers, and retardation of larval growth were recorded. The scallop populations inhabiting polluted areas of Peter the Great Bay seem to be incapable of normal reproduction. Development of offspring was a more sensitive index of disturbance of the reproductive function than morphology of scallop gonads. Analysis of the offspring development of common species of marine invertebrates is suggested to be used as a sensitive indicator of adverse environmental conditions.

Cotton is the most important natural source of fibre used in the textile industry, and is also a valuable source of oil. It belongs to the genus Gossypium (family Malvaceae) which comprises 50 species (Fryxell, 1992). The common species are the two old World diploids (2n = 2x = 26), G. arboreum L. and G. herbaceum L., and two American tetraploids (2n = 4x = 52), G. hirsutum L. and G. barbadense L. (Wendel et al., 1992); the tetraploids now dominate cotton production. Genetic improvement of cotton is necessary, both for increased yield and for upgrading the quality of lint. Cotton is propagated through seeds, and sometimes multiplied by cuttings. Extensive efforts have been made to develop plant types that can cope with various environmental hazards, insects, and diseases, and can give stable yield from year to year. However, conventional methods alone do not seem sufficient, and thus biotechnological approaches have been introduced (Bajaj & Gill, 1986, 1992).

One of the ways that rare species may qualitatively differ from common species is through extinction (exit) biases. The set of rare species may be biased by the selective elimination of species that cannot persist at low abundances (Kunin and Gaston, 1993). This chapter reviews the large paleontological literature on extinction for evidence that some rare species are more prone to extinction than others and for evidence about which traits promote such extinction-proneness. It will show that there is fossil evidence about both aspects. This evidence indicates that the set of rare species (however defined) is indeed biased in favour of those species with traits that promote species longevity by being resistant and/or resilient to disturbances. Traits that will be seen as promoting species longevity, and could operate in rare species, include widespread geographical range (for species that are locally sparse), wide niche breadth, morphological and behavioural simplicity, detritivory (and a suite of other traits in marine organisms) and small body size. The evidence for these traits is, as yet, only suggestive because of sampling problems in the fossil record, especially with rare species. But growing paleontological interest in extinction selectivity, especially at finer taxonomic scales, will provide ways to refine the evidence discussed here.

The purpose of this volume is to begin the complicated process of separating pattern from process. In a sense, it is an exercise that could be performed with any interesting pattern of species and their associated characteristics. We choose to focus our attention here on one particularly intriguing case: the differences between rare and common species. The choice is not completely arbitrary. The causes and consequences of species abundance have been a central concern of ecologists since the discipline began; indeed, some define ecology as the study of the distribution and abundance of species. The rise of conservation biology as a sub-discipline in recent years has served to focus additional attention on rarity and its implications, and has added to the importance of understanding the nature of rare—common differences.

In nearly two years of regular sampling 324 species of butterfly were recorded from the lowland rainforest within one kilometer of the Kuala Belalong Field Studies Centre (KBFSC), Batu Apoi forest reserve, Temburong, Brunei Darussalam. This represents over one third of the Bornean fauna and perhaps over half the total fauna of the area. Records are biased towards the more conspicuous Papilionidae and Pieridae with relatively smaller proportions of Nymphalidae, Lycaenidae and Hesperiidae being represented. Samples taken at approximately monthly intervals indicated relatively slight variation in species richness. However there was a steady turnover in species composition, presumably the result of changing species abundance relationships as most of the more common species experienced substantial and irregular fluctuations in numbers. Some closely related species pairs showed phenological dissociation in abundance, but many were phenologically unrelated or were positively associated. There was no evidence for seasonal trends in community composition or in the phenology of any particular species. While many species ranged freely throughout the area, some were more or less restricted to either riverbanks and open areas, the forest understorey, or the canopy, subcanopy and tops of major ridges. Certain Lycaenidae and Hesperiidae were extremely localized, being sometimes restricted to an area of a few hundred m2, presumably in the vicinity of their larval hostplants.

Kalahari Thomveld occupies an area of some 390,000 km2 in Namibia, Botswana and South Africa. It constitutes the southern portion of the arid or fine-leaved savanna on Kalahari sand codominated by grasses such as species of Eragrostis and Stipagrostis, and trees and shrubs, especially of the genus Acacia. Microclimatic and edaphic conditions in the subcanopy habitat under trees and shrubs often differ widely from those in the grassland. The subcanopy is unstable and subject to much disturbance, mainly due to its rich and varied fauna. A total of 132 plant species was recorded as typical for, or exclusive to the subcanopy habitat. These species tend to be widely to very widely distributed, and endemism was very low. Almost 50% were hemicryptophytes, 28% annuals and 9% succulents. The most common species were almost exclusively dispersed by animals, especially birds. Leguminosae, the family of most of the pioneer canopy formers, was almost absent from the subcanopy.

In The Netherlands 21 Characeae species occur. Chara vulgaris, C. globularis, and Nitella flexilis are common and widespread, occurring in at least 225 of the total of 1677 atlasblocks (5 × 5 km2). Chara aspera, C. contraria, C. major, Nitella mucronata and Tolypella prolifera, occurring in at least 30 atlasblocks, are denoted as ‘not uncommon’. Thirteen species are rare and recorded in less than 30 atlasblocks. Regarding the common species, the number of records significantly increased in recent time, presumably thanks to the recently increased flora inventory activities. The other species remained nevertheless rare, with a tendency of decrease. In the first half of this century mass occurrence of Characeae was a rather common phenomenon, especially in shallow lakes in the central western part of the country. Rich occurrence of Characeae is now restricted to localities with clear water which is low in nutrients. Important habitats are dune waters, polder ditches, shallow lakes and moorland pools. Physico-chemical factors in water and sediment, such as nutrients, salinity, CaCO3, alkalinity, and in the sediment also the redox-value and organic matter, are suggested as important parameters for species composition. In recent years, at several sites where water quality has improved by restoration measures, Characeae reappeared or increased in species and biomass.

The results of soil ciliate frequency studies of 47 field studies, from 12 ecosystem types, were combined with recent concepts and observations to assess the importance of soil ciliate biodiversity in ecosystem functioning. A few species typically furnish most of the individuals; increases in biodiversity, produced by less common species, alters soil ciliate communities. Soil ciliates were grouped according to position on the r/K continuum, with polyhymenophoran species as K, and colpodids as r organisms; and according to degree of soil affinity. Grasslands and hardwood forests were characterized by large numbers of K and intermediate species, whereas pine forests and more stressed ecosystems (e.g., arable lands, deserts) had more colpodid and fewer total species. Within these systems, certain species may become prominent, or be absent, suggesting that many soil ciliates exhibit widely overlapping niches, and that while a soil might function with a few species, high diversity allows systems to respond to changing seasons and climate.

The earthworm fauna of soils used for pasture-cereal rotations in south-eastern Australia was surveyed in 1990–91 (126 sites). Numbers were generally low (0–366 m-2, mean = 41.9 m-2 for all species combined). The fauna was dominated by introduced species. Aporrectodea rosea (Lumbricidae) was the most common species (mean = 31.4 m-2) followed by A. trapezoides (5.0 m-2). A. rosea and A. trapezoides were found at 45 and 29% of sites, respectively. There was no obvious relationship between earthworm abundance and soil pH.

Geographical and seasonal distributions of marine cladocerans in the coastal waters of southern China were studied. Penilia avirostris was the most common species, followed by Evadne tergestina and Podon schmackeri. P. avirostris and E. tergestina were most common during summer. P schmackeri, found only in a small bay northeast of Hong Kong, showed no clear seasonal pattern of occurrence. P avirostris and E. tergestina were found at temperatures ranging from 16–32 °C and salinity ranging from 7.3–37.2 %o. P schmackeri was restricted to a temperature range of 17–29 °C and a salinity range of 31.0–37.2 %o. No significant relationships between marine cladoceran abundance and chlorophyll a concentration were found in samples taken from Tolo Harbour. Parthenogenetic brood size of P. avirostris and E. tergestina ranged from 1 to 14, while P. schmackeri was found to carry up to 19 embryos per brood. No geographical trend in fecundity patterns was observed. No correlation was found between body length and brood size. The occurrence of females with resting eggs was rare.