Preliminary investigations on the distribution of scaled chrysophytes in Vermont and New Hampshire (USA) lakes and their utility to infer lake water chemistry

A total of 38 taxa of scaled chrysophytes, representing seven genera, were observed in the surface sediments of eleven lakes in Vermont and New Hampshire, USA. The number of taxa found per lake ranged from 10 to 23, with greater diversity and abundances of scales in the New Hampshire localities. The flora was similar to those described from other temperate regions of North America and Europe. The flora described from the New Hampshire waterbodies was typical of those observed in slightly acidic, dilute lakes situated in primarily forested watersheds. The flora observed in the Vermont lakes was more typical of ones previously described from regions rich in waterbodies with both high pH and concentrations of dissolved salts. The occurrences of several rarely reported species in North America, including Mallomonas alata, M. parvulu, M. retrorsu. and Synura lapponica , are documented. It was also determined that paleolimnological inference models developed in Connecticut for pH, specific conductivity and trophic score worked well using the scale remains from the study lakes.     

New records of Vaucheria species (Xanthophyceae) with associated Proales werneckii (Rotifera) from North America

The presence of galls on species of Vaucheria was investigated both seasonally and in a number of locations in North America. These galls are induced by the rotifer, Proales werneckii. In an Ohio stream, Vaucheria bursata and V. geminata were found to have galls throughout their growing season; September to January. Galls were most abundant in October and ranged in size from 90–260 μm in width and 140–790 μm in length. New records of Vaucheria with galls from locations in Alabama, California, Georgia, Louisiana, North Carolina, Ohio and Tennessee are reported. Three of the five taxa collected were not previously known to contain galls. In addition, worldwide literature on the distribution of these associated taxa was reviewed.     

THE EFFECT OF TEMPERATURE ON EGGS AND IMMATURE STAGES OF CULEX ANNULIROSTRIS SKUSE (DIPTERA: CULICIDAE)

Abstract
No immature stages of Culex annulirostris were found during field sampling in 1979–1980 when the average water temperature was < 17 °C; they reappeared when the average water temperature was 19 °C and reached the peak density (mean 107 immatures/cylinder) at 26.5 °C.
The effect of 6 temperatures (15–40°C) on egg hatching, development and survival of the immature stages of Cx annulirostris in the laboratory showed that at 15 and 40°C, eggs failed to hatch and larvae died in the first instars. The optimum temperatures for egg hatching and the survival of immature stages were 25 and 30°C. At these temperatures, 85 and 82% respectively of egg rafts hatched, the mean number of larvae per raft was 258 ± 9.8 and 260 ± 11.4 with immature survival of 83.5 and 79.0% respectively. Mean time to hatch at 20–35°C ranged from 1.2 d (35°C) to 2.9 d (20 °C). Developmental times from first instar to adult ranged from 7.1 d (35 °C) to 25.2 d (20 °C). The threshold for development of the immatures was 15.6 ± 2.5°C and the thermal constant was 142.9 ± 26.5 day—degrees (incubation temperatures 20–35°C). At less suitable temperatures of 20 and 35 °C, hatching (57.5 and 45%), number larvae per raft (mean 139.8 ± 9.8 and 102.6 ± 14.2) and survival were low.     

The distribution and ecology of Spiniferomonas (Chrysophyceae) in Connecticut (USA)

Siver, P. A. 1988. The distribution and ecology of Spiniferomonas (Chrysophyceae) in Connecticut (USA). - Nord. J. Bot. 8: 205–212. Copenhagen. ISSN 0107–055X.
The genus Spiniferomonas was found to be a common member of the phytoplankton flora in Connecticut lakes, present in over thirty-seven percent of the 113 samples collected during 1984. Thirteen of the 15 known freshwater Spiniferomonas species were found including S. crucigera , recorded for the first time from North America. Six species were new records for the United States. S. trioralis, S. bilacunosa and S. bourrellyi were the most common taxa. Ecological preferences of some species are presented. This study represents the first major survey of the genus in the United States.     

Temporal and spatial distribution of planktic cyanobacteria in Lake Kastoria, Greece, a shallow, urban lake

The temporal and spatial distribution of planktic cyanobacteria and some environmental parameters were studied in the shallow, urban Lake Kastoria, Greece from June 1996 to June 1997. Water temperature varied from 6–27 °C, pH from 7.5–8.9 and dissolved O₂ concentration from 0.7–12 mg m^-3 10^-3. The mean annual Chl a concentration was 83 mg Chl a m^-3 indicative of the eutrophic-hypertrophic state of the lake. Cyanobacterial biomass ranged from 11–238 g FW m^-3, constituting about 90% of the total phytoplankton biomass throughout the year. Cyanobacterial biomass was non-uniformly distributed both vertically and horizontally from August to November 1996 and resulted mainly from the distribution of Microcystis. Seven cyanobacterial taxa were reported for the first time in Lake Kastoria. Six taxa were dominant: Microcystis aeruginosa, M. flos-aquae, M. novacekii. Limnothrix redekei, Anabaena sp. and Cylindrospermopsis raciborskii. The dominant cyanobacterial taxa can be grouped on the basis of their distribution patterns (1) Microcystis species: maximum biomass occurring at pH > 8, temperature 12–17 °C, depth < 0.2 m; (2) Anabaena sp. and Cylindrospermopsis raciborskii : maximum biomass at temperatures 23–26 °C; (3) Limnothrix redekei : maximum biomass at temperatures 6–27 °C. Usually, non-uniform, vertical distributions of cyanobacterial biomass were associated with the formation of temperature, pH and O₂ gradients. L. redekei was considered to be a key lake organism since it contributed up to 59% of the cyanobacterial biomass. Interestingly, three of the dominant cyanobacteria Microcystis aeruginosa, Anabaena sp. and Cylindrospermopsis raciborskii belong to genera that include toxin-producing species.     

Water temperature fluctuations and territoriality in the intertidal zone: two possible explanations for the elevational distribution of body size in Graus nigra

On the central coast of Chile, distribution of body size in Graus nigra varied with tidal pool height. With the objective of determining whether environmental temperature is one of the possible causes which explains the observed distribution pattern, two behavioural responses were analysed during an experimental period of increasing water temperature: number of opercular movements (an indirect measure of energy expenditure) and activity levels. The interactions of temperature × time and body size × time had a significant effect on the number of opercular movements. At low temperatures (13–15° C), large fish reached a maximum number of opercular movements, while small fish reached a maximum only at high temperatures (23–25° C). The interaction temperature × time had a significant effect on activity levels of different body sizes. In general, large fish appeared to be less active than small fish, however, at very high temperatures (24–26° C) all individuals increased their activity levels. These data indicate that small fish are acclimatized to live in a wider range of temperatures (13–23° C), and, for fish of all body sizes, the highest temperatures (23–26° C) probably constitute a suboptimal microhabitat. Strong territoriality was observed, with large individuals displacing smaller individuals. These data suggest that temperature is an important factor in explaining why large individuals are not present in high tidal pools (high temperatures), whereas territoriality explains why small individuals are not in low tidal pools (habitat of large individuals).     

PHYLOGEOGRAPHY OF BATRACHOSPERMUM MACROSPORUM (BATRACHOSPERMALES,RHODOPHYTA) FROM NORTH AND SOUTH AMERICA1

Phylogeographic trends in Batrachospermum macrosporum Mont. were investigated using the mitochondrial intergenic spacer between the cytochrome oxidase subunit 2 and 3 genes (cox2‐3). A total of 11 stream segments were sampled with seven in the coastal plain of North America and four in tropical areas of South America. Fifteen thalli were sampled from seven streams, 14 thalli from two streams, and eight thalli from two streams. There were 16 haplotypes detected using 149 individuals. Of the eight haplotypes from locations in North America, all were 334 base pairs (bp) in length, and of those from South America, five were 344 bp, and three were 348 bp. Two individual networks were produced: one for the haplotypes from North America and another for those from South America, and these could not be joined due to the large number of base pair differences. This split between haplotypes from North and South America was confirmed with sequence data of the rbcL gene. There was very little genetic variation among the haplotypes from the North American locations, leading us to hypothesize that these are fairly recent colonization events along the coastal plain. In contrast, there was high variation among haplotypes from South America, and it would appear that the Amazon serves as a center of diversity. We detected considerable variation in haplotypes among streams, but frequently, a single haplotype in an individual stream segment, which is consistent with data from previous studies of other batrachospermalean taxa, may suggest a single colonization event per stream.     

Invaders are not a random selection of species

We assembled information on 119 species of freshwater macroinvertebrate invaders in North America and Europe, and compared them to all native freshwater species in North America and Europe. We tested whether the invaders were a random or selected group among taxa (phylum or class), water quality requirements, and feeding habit. We found that freshwater macroinvertebrate invaders are not a random selection of species, and are over-represented by molluscs and crustaceans, while taxa richness of native communities are dominated by insects. Over 35% of native species of aquatic invertebrates in North America are only able to live in areas with excellent or very good water quality, and are intolerant of organic pollution. In contrast, all invaders are tolerant of at least moderate amounts of organic pollution. There was a significant difference in the distribution of feeding habits between native species and invaders: collector-filterers (including suspension feeders) were 2.5–3 times more abundant, and predators were 3–4 times less abundant among invaders than among native invertebrates. The ongoing spread of exotic species affects the biodiversity of selected taxa, shifts communities toward greater tolerance of organic pollution and increases the numbers of suspension feeders, thereby enhancing benthic pelagic coupling in waterbodies with high densities of invaders. Because these processes are very similar in Europe and North America, we suggest that the observed patterns may have a common global effect.     

Historical biogeography of Hexabathynella , a cosmopolitan genus of groundwater Syncarida (Crustacea, Bathynellacea, Parabathynellidae)

Hexabathynella is the only cosmopolitan genus of the order Bathynellacea (Crustacea). The known species number 18, found in Europe (9), Africa (1), South America (2), North America (3) and Australia and New Zealand (3). Phylogenetic analysis suggests that the least derived species are those from South America and the most derived those from the Iberian Peninsula, North America and Australia. The five species with the most plesiomorphic characters occur in salt or brackish water, which supports a marine origin for the genus. Phylogenetic and biogeographical analyses suggest that the distribution of the genus can be explained by dispersion and a double vicariant biogeographical model based on plate tectonics and the evolution of the Tethys during the Mesozoic and Cenozoic.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 457–466.     

Phylogeography of the North American red fox: vicariance in Pleistocene forest refugia

Fossil, archaeological, and morphometric data suggest that indigenous red foxes in North America were derived from vicariance in two disjunct refugia during the last glaciation: one in Beringia and one in the contiguous USA. To test this hypothesis, we conducted a phylogeographical analysis of the North American red fox within its presettlement range. We sequenced portions of the mitochondrial cytochrome b (354 bp) gene and D-loop (342 bp) from 220 historical red fox specimens. Phylogenetic analysis of the cytochrome b gene produced two clades that diverged c . 400 000 years before present ( bp ): a Holarctic and a Nearctic clade. D-loop analyses of the Nearctic clade indicated three distinct subclades (≥ 99% Bayesian posterior probability); two that were more recently derived (rho estimate c . 20 000 bp ) and were restricted to the southwestern mountains and the eastern portion of North America, and one that was older (rho estimate c . 45 000 bp ) and more widespread in North America. Populations that migrated north from the southern refugium following deglaciation were derived from the colonization of North America during or prior to the Illinoian glaciation (300 000–130 000 bp ), whereas populations that migrated south from the northern refugium represent a more recent colonization event during the Wisconsin glaciation (100 000–10 000 bp ). Our findings indicate that Nearctic clade red foxes are phylogenetically distinct from their Holarctic counterparts, and reflect long-term isolation in two disjunct forest refugia during the Pleistocene. The montane lineage, which includes endangered populations, may be ecologically and evolutionarily distinct.     

Morphology,phylogenetic position and ecophysiology of Alexandrium ostenfeldii (Dinophyceae) from the Bohai Sea,China

Alexandrium ostenfeldii is a potentially toxic dinoflagellate that often occurs in coastal areas at high latitudes. Here we report the presence of A. ostenfeldii in the Bohai Sea, China, for the first time. The vegetative cells of A. ostenfeldii are characterized by a narrow first apical plate and a large ventral pore located on the anterior right side. Partial large subunit sequence comparison revealed that the Chinese strain differs from the Finnish strains at only three positions, and from A. peruvianum of Spain at five positions. Maximum parsimony analysis revealed that A. ostenfeldii from China and Finland and A. peruvianum from Spain grouped together. They were the nearest sister group to a clade with A. ostenfeldii from New Zealand, Europe, and North America. In culture, growth did not occur at temperatures below 9 °C and occurred at salinities between 7 and 27 psu. It took 10–20 days for newly formed cysts to mature at 20 °C. Lower temperature delayed germination, but the germination rate exceeded 90% at temperatures from 12 to 24 °C. No germination occurred below 9 °C after 1 month of incubation. The Chinese strain of A. ostenfeldii produced neither spirolides nor paralytic shellfish poisoning toxins.     

Embryonic development, larval growth and life cycle of Coenagrion puella (Odonata: Zygoptera) from an Austrian pond

SUMMARY. 1. Newly-laid eggs of Coenagrion puella (L.) from a pond near Herzogenburg (Lower Austria) were kept at constant water temperatures (range c .3.5°C to c .28°C)in the laboratory. Hatching success varied with temperature; no eggs hatched below 12°C and nearly all hatched at c .l6°C. Hatching time decreased with increasing temperature and the relationship between the two variables within the range 12–28 °C was well described by a power law. The length of the hatching period was less than 12 days. Hatching times estimated from the power-law equations and those obtained in the field experiments were similar. Therefore both the hatching time and the length of the hatching period in the field could be estimated from the laboratory data for the range 12–28°C.
2. The maximum number of instars from egg to imago was 11; the average body length increment (mm) per moult was proportionately constant at c .26% and Dyar's rule was applicable. The interval between moults decreased with increasing temperature up to the seventh instar and the relationship between the two variables within the range 12–28°C was well described by a power law. The moulting interval for instars 8–11 ranged from 23 to 48 days and was relatively independent of temperature. No moulting occurred at temperatures below 12°C.
3. Larval growth was logistic in the laboratory and variations in mean logistic growth rate (range 0–2.5% length day⁻¹) were related to mean temperature with no growth at temperatures <12°C. Larval growth rates in pond experiments were similar to those estimated from laboratory data, and therefore the regression equations obtained from the laboratory experiments are probably applicable to larval growth in the field.
4. Information on the life cycle of C. puella is briefly reviewed and it is concluded that C. puella from the pond near Herzogenburg has an univoltine life cycle.     

Population Genetics and Identity of an Introduced Terrestrial Slug: Arion subfuscus s.l. in the North-east USA (Gastropoda, Pulmonata, Arionidae)

Several European species of the terrestrial slug genus Arion have been introduced into North America. A case in point is the species complex A. subfuscus s.l. which has become one of the most abundant slug taxa in North America. In Europe this complex consists of at least two cryptic species, viz. A. fuscus and A. subfuscus s.s., the latter of which is further subdivided in five strongly divergent mtDNA lineages (A. subfuscus S1–S5). In order to determine which of these A. subfsucus s.l. taxa are present in the NE USA and in order to assess their population genetic structure, we compared mtDNA, nDNA and allozyme variation between populations from the NE USA and Europe. Our results show that (1) at least A. subfuscus S1 has become successfully established in the NE USA, (2) founder effects are the most likely explanation for the loss of a large amount of molecular genetic variation in populations from the NE USA (i.e. a loss of 96% of the 16S rDNA haplotypes, 67% of the ITS1 alleles and 46% of the alleles at polymorphic allozyme loci), and (3) part of the remaining genetic variation in NE USA populations was probably due to multiple introductions from the British Isles and the European mainland, and the hybrid structure of most of these source populations. Apparently, the extreme loss of molecular genetic variation in this introduced species has not prevented it from successfully establishing and spreading in novel environments.     

Experimental climate warming decreases photosynthetic efficiency of lichens in an arid South African ecosystem

Modest increases in global temperature have been implicated in causing population extirpations and range shifts in taxa inhabiting colder environs and in ectotherms whose thermoregulation is more closely tied to environmental conditions. Many arid-adapted endotherms already experience conditions at their physiological limits, so it is conceivable that they could be similarly affected by warming temperatures. We explored how climatic variables might influence the apparent survival of the banner-tailed kangaroo rat (Dipodomys spectabilis), a rodent endemic to the Chihuahuan Desert of North America and renowned for its behavioral and physiological adaptations to arid environments. Relative variable weight, strength of variable relationships, and other criteria indicated that summer, diurnal land surface temperature (SD_LST) was the primary environmental driver of apparent survival in these arid-adapted rodents. Higher temperatures had a negative effect on apparent survival, which ranged from 0.15 (SE = 0.04) for subadults to 0.50 (SE = 0.07) for adults. Elevated SD_LST may negatively influence survival through multiple pathways, including increased water loss and energy expenditure that could lead to chronic stress and/or hyperthermia that could cause direct mortality. Land surface temperatures are predicted to increase by as much 6.5°C by 2099, reducing apparent survival of adults to ~0.15 in some regions of the species’ range, possibly causing a shift in their distribution. The relationship between SD_LST and survival suggests a mechanism whereby physiological tolerances are exceeded resulting in a reduction to individual fitness that may ultimately cause a shift in the species’ range over time.     

Distribution of Sexual and Agamospermous Populations of Eupatorium (Compositae) in Asia

Abstract Examinations of chromosome number voucher specimens show that sexual diploid and agamospermous polyploid plants of Eupatorium in Asia can be distinguished by morphology, fertility, and stainability of pollen grains. Using these criteria, reproductive systems (sexual vs. agamospermous) were estimated for 558 herbarium specimens of Eupatorium in East Asia. Of 22 taxa examined, six included both sexual and agamospermous specimens; those of one taxon were all agamospermous; and those of 15 taxa were all sexual. This result shows that 21 taxa are not agamospermous microspecies but are differentiated at the diploid level. Sexual populations of most taxa had restricted geographical distributions. Eupatorium chinense var. chinense and var. oppositifolium consisted of both sexual and agamospermous populations. Sexual populations of these two varieties were allopatric and distinct in external morphology, suggesting differentiation at the species level. The specimens of E. heterophyllum s. str. were all agamospermous, while those of E. mairel , often treated as synonymous with E. heterophyllum , were sexual.
In comparing East Asian and North American Eupatorium for the distributional patterns of sexual and agamospermous populations, three differences can be pointed out: (1) Agamospermous plants of autopolyploid origin have evolved in eight species and are widespread in North America; while most agamospermous plants in East Asia may be of allopolyploid origin, have relatively restricted ranges, and are less frequent than the diploid plants with the exception of in E. chinense var. oppositifolium , (2) The number of sexual species with wide range is greater in North America than in East Asia. (3) The number of sexual species with restricted ranges is greater in East Asia than in North America. The results obtained suggest that speciation among the plants of Eupatorium has occurred more recently in East Asia than in North America.     

Assembly of Alaska‐Yukon boreal steppe communities: Testing biogeographic hypotheses via modern ecological distributions

Beringia (eastern Asia, Alaska, northwest Canada) has been a land‐bridge dispersal route between Asia and North America intermittently since the Mesozoic Era. The Quaternary, the most recent period of exchange, is characterized by large, geologically rapid climate fluctuations and sea‐level changes that alternately expose and inundate the land‐bridge region. Insights into how Quaternary land‐bridge geography has controlled species exchange and assembly of the North American flora comes from focusing on a restricted community with narrow ecological tolerances: species that are today restricted to isolated steppe habitats (dry grasslands) in the Subarctic. We evaluated (i) potential controls over current spatial distributions of steppe plants and their pollinators in Alaska and Yukon and (ii) their ecological distributions in relation to potential biogeographic histories. Taxa present in North America that are disjunct from Asia tended to have larger altitudinal ranges (tolerating colder temperatures) than taxa disjunct from farther south in North America, which were largely restricted to the warmest, lowest‐elevation sites. Ecological findings support the following biogeographic scenarios. Migration from Asia via the land‐bridge occurred during Quaternary glacial periods when conditions were colder and drier than today. While a corridor for migration of cold‐tolerant species of cold steppe and tundra, the land bridge acted as a filter that excluded warmth‐demanding species. Migration from North America occurred under warm, dry interglacial conditions; thermophilous North American disjuncts taking this route may have long histories in Beringia, or they may have migrated recently during the relatively warm and dry early Holocene, when forest cover was incomplete.     

What,if anything,is a ‘typical’ viper? Biological attributes of basal viperid snakes (genus Causus Wagler, 1830)

For many major phylogenetic radiations of organisms, the available ecological knowledge is disproportionately derived from a small minority of taxa, and sometimes from organisms that are highly atypical. Viperid snakes provide a good example of this situation; high-latitude cold-climate taxa in northern Europe (vipers) and North America (rattlesnakes) have been studied intensively, but more speciose radiations in tropical Africa, Asia, and Central America remain poorly known. We dissected > 500 specimens (six species) of night adders (genus Causus ), mostly from Cameroon (68%) in equatorial Africa, to quantify morphology, diets, and reproductive biology. By contrast to the 'slow' life-histories of cold-climate viperids, night adders feed frequently on frogs (rather than infrequently on mammals), and produce frequent large clutches of relatively small eggs (rather than infrequent small litters of relatively large live young). Thus, putatively 'typical' viperid attributes such as low fecundity, viviparity, and predation on mammals reflect adaptations to the invasion of cold environments by a small and perhaps atypical subset of viperid taxa. Our data on prey size suggest that one of the critical innovations of early viperids may have been an ability to subdue and ingest relatively large prey.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 575–588.     

Morphological and molecular comparisons ofCampsis grandiflora andC. radicans (Bignoniaceae), an eastern Asian and eastern North American vicariad species pair

Morphological and molecular comparisons were made forCampsis grandiflora (Thunb.)K. Schumann (Bignoniaceae) from eastern Asia andC. radicans (L.)Seemann from eastern North America. Chloroplast DNA (cpDNA) variation was surveyed with 20 restriction endonucleases. The cpDNA divergence between the two vicariad species was 2.44%, which is the highest reported among North Temperate disjunct taxa and one of the highest reported for infrageneric taxa. Detailed morphological comparisons also suggest a high level of divergence. Cluster analyses based on 22 morphological characters and 39 OTUs revealed two distinct groups corresponding with the two species. The average taxonomic distance between the two species was 1.806. Analyses of variance (ANOVA) revealed that 12 of the 18 quantitative characters differed significantly ( 0.01) betweenC. grandiflora andC. radicans. Divergence time based on cpDNA data was estimated as 24.4 million years. The Bering land bridge hypothesis was favored over the North Atlantic land bridge hypothesis based on the estimated divergence time and the geological history of the North Temperate region. The high levels of morphological and cpDNA divergence are not consistent with morphological stasis, which has been proposed as a common mode of evolution for North Temperate disjunct taxa.     

Comparison of 18S and ITS-1 rDNA sequences of selected geographic isolates of Myxobolus cerebralis.

Myxobolus cerebralis, the myxosporean parasite-causing salmonid whirling disease, was first reported among rainbow trout (Oncorhynchus mykiss) in Germany in 1903. The parasite was reported for the first time in North America in 1958 among hatchery-reared trout in the eastern USA, presumably arriving with frozen trout shipments from Europe. A comparison of 18S and ITS-1 ribosomal DNA sequences was conducted to identify potential strain differences between selected geographic isolates of this parasite from Europe and North America. Only fourteen of 1700 base pairs were different in the 18S rRNA gene from isolates obtained from California and West Virginia in the USA, and the Federal German Republic. No evidence for strain differences was obtained from ITS-1 sequences that were found to be identical among all parasite isolates. This finding is consistent with the hypothesis that the parasite was recently introduced to the USA from Europe.