Diversity and zoogeography of the fairy shrimps (Branchiopoda: Anostraca) on the Indian subcontinent

The Indian subcontinent has a specific biogeographical history, but has remained understudied with respect to invertebrates like the Anostraca. In this study, we discuss the anostracan diversity and zoogeography on the subcontinent. We collected all pertinent literature and considered nineteen bioclimatic variables along with altitude and its terrestrial ecoregions. The study area was overlaid with 10,000 km² grids, and five hundred random GIS data points per grid were extracted for analysis besides the species locality data. Species richness estimators predict at least 3–4 more species to the existing list of 19 species. The beta diversity measure βsim reveals two zoogeographic “zones,” viz., a Northern (NZ) zone and the rest of the subcontinent (RS) comprising the Central (CZ) and South (SZ) zones by Unweighted Pair-Group Method using arithmetic averages clustering and Analysis of Similarity. Complementarity index shows that no fauna is shared between NZ and RS, while CZ and SZ share 50% of the species. Principal Component analysis shows that NZ and RS differ somewhat from one another climatically. NZ and RS have different ecoregions with montane and temperate grasslands commonly observed in NZ while the latter comprising tropical forests, implying differences in soil geochemistry which is crucial for anostracan distribution.     

Supplement to " checklist="" of="" the="" anostraca""="

Our 1995 "Checklist of the Anostraca" covered all species described through 31 December 1993 along with those described in the volume from the Second International Large Branchiopod Symposium (Hydrobiologia 298). This supplement includes new species (14) described through 31 December 1996, one change in rank and one new species discussed in this symposium volume, anew synonym, and correction of errors discovered in the original. We do not update new range extensions. With these additions and changes, we number the named anostracan fauna of the world at 273 species and six subspecies organized in 23 genera. The need for more study of anostracan zoogeography is again demonstrated by the fact that seven of the 16 species added to the checklist are know only from their type localities. Until we have more complete information on the distributions of the species, it will not be possible to make an accurate evaluation of the status of anostracan biodiversity. This revised version was published online in August 2006 with corrections to the Cover Date.     

EXPERIMENTAL MESOCOSM STUDIES OF SALINITY EFFECTS ON THE BENTHIC ALGAL COMMUNITY OF A SALINE LAKE

As closed-basin systems, saline lakes are prone to fluctuate in level and salinity with climate change and hydrologic alterations. Loss of many Great Basin lakes has resulted from the diversion of tributary streams for agricultural or municipal uses. At Mono Lake, an alkaline salt lake in eastern California, salinities have risen from 50 to 100 g·L^?1 in just 50 years. Experimental mesocosms were established to simulate some of the potential ecological effects that could have accompanied this change. The influence of salinity on diatom diversity, taxonomic structure, and primary production was tested using mesocosms deployed at Mono Lake. Mesocosm tanks were 500 L in volume, 1 m square, and 0.5 m deep, with open tops covered by 1 mm mesh net. Five treatments (50, 75, 100, 125, and 150 g·L^?1) with four replicates per treatment were used over a 2-month period. The diatom-dominated benthic algae were reduced both in standing crop (from 6 to <0.1 g·m^?2) and diversity (from 30 to 12 taxa) with increased salinity, with most loss occurring in salinities ≥75 g·L^?1. Photosynthetic oxygen production also was significantly lower at salinities ≥75 g·L^?1. Diatom indicator taxa for these shifts included Denticula sp., Nitzschia frustulum, N. monoensis, N. communis, and Stephanodiscus oregonicus increasing in relative abundance in higher salinity treatments, accompanied by decreases in Achnanthes minutissima, Cymbella minuta, N. dissipata, and Rhoicosphenia abbreviata. Exhibiting dominance at moderate salinity levels (75 to 125 g·L^?1) were Nitzschia frustulum, N. communis, N. palea, and Navicula crucialis. These latter species may be limited by both physiological stress at high salinity and grazing and competition at low salinity. The filamentous chlorophyte, Ctenocladus circinnatus, and cyanobacteria (Oscillatoria spp.) occurred only in salinity treatments from 50 to 100 g·L^?1. Diversion of tributary stream flow and resulting salinity increases in this lake threaten sustained benthic primary production and algal species diversity relative to conditions prior to stream diversion. The 1994 decision of the California State Water Resources Control Board to return stream flows to Mono Lake will raise the lake level and reduce salinity to around 75 g·L^?1 and is expected to increase the diversity and productivity of the benthic algae of this ecosystem.     

New records of large branchiopods (Branchiopoda: Anostraca,Notostraca, and Spinicaudata) in Mexico

This paper reports new distribution records of large branchiopods for Mexico following a three year survey of the Baja California peninsula. The occurance of the anostracans Thamnocephalus mexicanus (Linder, 1941) and T. platyurus (Packard, 1877), the notostracan Lepidurus lemmoni (Holmes, 1894), and the spinicaudatans Eulimnadia cylindrova (Belk, 1989) and E. texana (Packard,1871), all represent the first records for the peninsula. An undescribed species of the anostracan genus Streptocephalus is recorded from the state of Baja California (Norte). The occurrence of the notostracan genus Triops and four other anostracan species on the peninsula is also confirmed. The conchostracan Cyclestheria hislopi (Baird, 1859) is recorded from the state of Quintana Roo. The collections of Lepidurus and Cyclestheria are the first records for México. These records increase the number of species of large branchiopods reported fromMéxico to 36: 20 Anostraca, 3 Notostraca, 11 Spinicaudata, and 2Laevicaudata. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of increasing salinity on anArtemia population from Mono Lake,California

Summary Salinity increased from 48 to 93 g/l total dissolved solids (TDS) in Mono Lake, California between 1941 and 1982, and is expected to fluctuate between 169 and 248 g/l at equilibrium by the middle of the next century. In order to predict the consequences of this trend on the Mono Lake ecosystem, we determined effects of salinity on survival, growth, reproduction and hatching ofArtemia monica, Mono Lake's only macrozooplankton species. Seven salainities ranging from 76 to 179 g/l were tested in a long-term experiment to determine both lethal and sublethal responses. The salt tolerance limit for subadultA. monica was between 159 and 179 g/l. Adult size, growth rates, and brood sizes decreased, and female mortality during reproduction increased, as salinity increased. Hatching of diapause eggs was delayed and total percent hatch decreased as salinity increased, and hatching failed at 159 g/l. The life-time reproductive potential of individual females decreased linearly over the seven salinities tested. Based on this study, we predict a decrease in the productivity of theA. monica population in Mono Lake and extinction of the species is probable before the lake reaches equilibrium.     

Dispersal of Artemia franciscana Kellogg (Crustacea; Anostraca) populations in the coastal saltworks of Rio Grande do Norte, northeastern Brazil

In spite of the presence of Artemia franciscana Kellogg in several saltworks in the State of Rio Grande do Norte (RN) (northeastern Brazil) that were colonized from inoculations made in Macau (RN) in April 1977 with cysts from a San Francisco Bay (California, U.S.A.) stock, there is no recent data on the degree of regional dispersal of this anostracan. For 12 months (July 1996 – June 1997), 55 saltworks located in the municipalities of Areia Branca, Grossos, Galinhos, Guamaré and Macau in RN were visited and sampled for the presence of Artemia franciscana and the occurrence of its cysts. Populations of Artemia franciscana were found in all 55 saltworks, although significant amounts of cysts were only found in six sites. The presence of Artemia franciscana in all visited sites brings further evidence to the ample dispersal of this anostracan throughout the saltwork region of RN. However, the relatively low incidence of cysts suggests that most of these populations are reproducing ovoviviparously.     

Patterns of vegetation along a spatiotemporal gradient on shoreline strands of a desert basin lake

Shoreline strands of Mono Lake, California, show clear evidence ofregular temporal change in plant communities and the soils associated with themalong a primary successional sere, contradicting the traditional notion thatsuccession sensu stricto does not occur in aridenvironments. We documented spatial patterns, and inferred temporal patternsfrom aerial photographs taken each decade from 1930, in communities ofperennialshrubs and in characteristics of the physical environment in sand-duneand shoreline ecosystems on the north shore of Mono Lake, a receding terminalQuaternary lake in the Great Basin desert of the United States that is highlysaline and alkaline. Our study plot was aligned with an extreme physicochemicalgradient, representing a primary sere beginning with the historic, acceleratedregression of Mono Lake since 1940 and ending with upland surfaces exposed bylake regression between 500 and 1000 years ago. Four shrub species composedmost of the 7–11% percent coverof perennial vegetation: populations of Sarcobatusvermiculatus extended farthest toward the lake and colonized themostrecently exposed and toxic surfaces; populations of Chrysothamnusnauseosus, Tetradymia tetrameres, andC. viscidiflorus ended at increasing distances (inthis order) from the lake shore, reflecting each species'respectivelylower tolerance of soil salinity, alkalinity, and toxic soil elements ratherthan the ability to disperse. Values of soil variables that decrease plantgrowth and establishment (EC, pH, B, S) were lower in oldersubstrates, in the upper soil horizons, and at increasing distances from thelake, reflecting leaching and other pedogenic processes with time. Individualsof S. vermiculatus appeared to promote dune building bytolerating burial, enhancing their own growth and establishment, and catchingmore sand. We hypothesize that this process also facilitates the establishmentof less stress tolerant species. Plant nutrients (N, P) decreasedwithdepth, evidence of progressive soil enrichment by litter and leaf fall. Thusboth allogenic processes (weathering of parent material) andautogenicprocesses (facilitation in particular) resulting fromplant-environment interactions occurred and contributed to ecosystemchange in this extreme primary sere, adhering to the strictest definition ofsuccession.     

On the larval development of<Emphasis Type="Italic"> Eubranchipus grubii</Emphasis> (Crustacea,Branchiopoda, Anostraca), with notes on the basal phylogeny of the Branchiopoda

Selected larval stages of Eubranchipus grubii (Anostraca) from Danish temporary waters are examined by scanning electron microscopy in a phylogenetic context. The study focuses on limb development and body segmentation. It is shown that the large, proximal endite of the trunk limbs in the adult Anostraca is actually a fusion product of two smaller endites which make their appearance in the early larval development. This gives a total of six endites along the inner margin of the trunk limbs. An unsegmented endopod follows more distally. A small additional, seventh endite makes a short appearance in late larvae, but has disappeared in the adults. The naupliar feeding apparatus is of the same type as found in other branchiopods, and has previously been suggested as an autapomorphy for the Branchiopoda. The similarities between the naupliar feeding apparatus of E. grubii and other branchiopods include the presence of a long protopod with a characteristic morphology of the coxal and basipodal masticatory spines/setae, and a three-segmented mandibular palp (basipod and two endopod segments) with a largely similar setation in all taxa. The mode of trunk limb development is also the same as seen in most other recent branchiopods. The phylogenetic significance for the basal phylogeny of the Branchiopoda of these and other morphological features is discussed in relation to the phylogenetic position of two branchiopod fossils, Lepidocaris rhyniensis and Rehbachiella kinnekullensis. While R. kinnekullensis has previously been suggested to be a stem lineage branchiopod, the position of L. rhyniensis is more uncertain. Three different possible phylogenetic positions of L. rhyniensis are discussed: (a) L. rhyniensis as a stem lineage anostracan, (b) L. rhyniensis as a stem lineage branchiopod or (c) L. rhyniensis as a stem lineage phyllopod. It seems most plausible to consider L. rhyniensis a stem lineage anostracan.     

A New Species of Streptocephalus Fairy Shrimp (Crustacea,Anostraca) with Tetrahedral Cysts from Central Thailand

A new species of fairy shrimp, Streptocephalus siamensis n. sp., is described from five temporary pools in Suphan Buri and Kanchana Buri Provinces, central Thailand. It sometimes co‐occurs with its congener, S. sirindhornae . This new species belongs to the subgenus Parastreptocephalus which is defined by bearing tetrahedral cysts. This is the third anostracan species reported from Thailand. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Anostraca of the Indian Subcontinent

There are 15 species of Anostraca belonging to 6 genera on the Indian Subcontinent. These are:Artemia sp. (reportedly a bisexual form of undetermined species);Artemia parthenogenetica Bowen & Sterling, 1978;Branchinecta orientalis Sars, 1901;Branchinella hardingi (Qadri & Baqai, 1956);Branchinella kugenumaensis (Ishikawa, 1895);Branchinella ornata Daday, 1910;Branchipodopsis acanthopenes (Malhotra & Duda, 1970);Branchipodopsis affinis Sars, 1901;Branchipus schaefferi Fischer, 1834;Chirocephalus priscus (Daday, 1910);Streptocephalus dichotomus Baird, 1860;Streptocephalus echinus Bond, 1934;Streptocephalus longimanus Bond, 1934;Streptocephalus simplex Gurney, 1906;Streptocephalus spinifer Gurney, 1906.Comparing numbers of species for southern India with other reasonably well studied areas, demonstrated that anostracan species richness is higher in the climatically more varied temperate regions than it is in the more uniform tropics. Tropical South India has six species compared to 13 in Arizona (USA), 19 in California (USA), 10 in Morocco, and 14 in Italy.     

Resilience of anostracan cysts to fire

California's Mediterranean ecosystems include shrubland and grassland vegetation types that are fire-prone. Dotted within this landscape are ephemeral wetlands called vernal pools. Since surrounding upland vegetation is adapted to survive fire, it is expected that vernal pool organisms should be able to survive as well. One group of animals common to vernal pools are anostracan crustaceans that survive the pool's dry period as encysted embryos. We hydrated anostracan cysts from the soil of a recently burned pool and from soil samples intentionally burned in a prescribed fire. We also sampled burned pools when refilled the next rainy season. We found that anostracan cysts in the soil can survive fire and that shrimp occur in pools in the first post-burn season. This information is important from a management perspective concerning fire effects, controlled or natural, on vernal pools and their rare and endangered species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molecular Analysis of the Sulfate Reducing and ArchaealCommunity in a Meromictic Soda Lake (Mono Lake, California) by Targeting 16S rRNA, mcrA, apsA, and dsrAB Genes

Sulfate reduction is the most important process involved in the mineralization of carbon in the anoxic bottom waters of Mono Lake, an alkaline, hypersaline, meromictic Lake in California. Another important biogeochemical process in Mono Lake is thought to be sulfate-dependent methane oxidation (SDMO). However little is known about what types of organisms are involved in these processes in Mono Lake. Therefore, the sulfate-reducing and archaeal microbial community in Mono Lake was analyzed by targeting 16S rRNA, methyl-coenzyme M reductase (mcrA), adenosine-5′-phosphosulfate (apsA), and dissimilatory sulfite reductase (dsrAB) genes to investigate the sulfate-reducing and archaeal community with depth. Most of the 16S rRNA gene sequences retrieved from the samples fell into the δ-subdivision of the Proteobacteria. Phylogenetic analyses suggested that the clones obtained represented sulfate-reducing bacteria, which are probably involved in the mineralization of carbon in Mono Lake, many of them belonging to a novel line of descent in the δ-Proteobacteria. Only 6% of the sequences retrieved from the samples affiliated to the domain Euryarchaeota but did not represent Archaea, which is considered to be responsible for SDMO [Orphan et al. 2001: Appl Environ Microbiol 67:1922–1934; Teske et al.: Appl Environ Microbiol 68:1994–2007]. On the basis of our results and thermodynamic arguments, we proposed that SDMO in hypersaline environments is presumably carried out by SRB alone. Polymerase chain reaction (PCR) amplifications of the mcrA-, apsA-, and dsrAB genes in Mono Lake samples were, in most cases, not successful. Only the PCR amplification of the apsA gene was partially successful. The amplification of these functional genes was not successful because there was either insufficient “target” DNA in the samples, or the microorganisms in Mono Lake have divergent functional genes.     

FACTORS DETERMINING A CLUTCH SIZE REDUCTION IN CALIFORNIA GULLS (LARUS CALIFORNICUS): A MULTI-HYPOTHESIS APPROACH

In the thirty-five years since David Lack first highlighted the importance of clutch size, a large number of hypotheses have been proposed relating clutch size variation to various environmental and demographic factors. Despite a great deal of both empirical and theoretical work on clutch size, there has been very little effort to test many of the competing hypotheses in explaining a clutch size difference between two populations of the same species. I have taken the latter approach in an effort to explain a clutch size reduction in the California Gull (Larus californicus) population at Mono Lake, California. I compared the breeding biologies of the gulls at Mono Lake and at Great Salt Lake, Utah, collecting data for three breeding seasons at Mono Lake and one breeding season at Great Salt Lake. These data included measurements of the conditions of 60 adults, growth and mortality measurements for approximately 900 chicks, 4450 nest-hours of parental care observations, and the results of egg-removal experiments on 40 females. I tested seven hypotheses to explain the clutch size reduction: age structure, egg predation, bet-hedging, effort reallocation, most productive brood size, parental mortality, and pre-egg food limitation. Each of these hypotheses is described in detail in the introduction. The pre-egg food limitation hypothesis is best able to explain the clutch size reduction at Mono Lake, although the egg-removal experiments show that the resource limitation is relative and not absolute. Clutch size variation at each site need not be viewed as the result of fine-scaled evolutionary adjustment, although the general clutch size decision machinery is presumably molded by selection. Future research must focus on the details of this clutch size decision machinery and its application to the concept of reproductive effort.     

Cis-and all-trans-canthaxanthin levels in fairy shrimps

The carotenoid composition of cysts of seven species of fairy shrimps (Anostraca) was studied using high-performance liquid chromatography. Canthaxanthin was detected as the major pigment, but an important and often predominant fraction of it occurred in the cis-configuration, which is consistent with previous findings in Artemia cysts. Cis-canthaxanthin rapidly disappeared in nauplii of Thamnocephalus platyurus through conversion to all-trans-canthaxanthin and was preferably localized in the abdominal section carrying the genital segment of females, unlike in mature male animals. In contrast, the intense orange-red colour of the thoracopods and the cercopods in both sexes was only due to all-trans-canthaxanthin.     

Morphological Characterization of Viruses in the Stratified Water Column of Alkaline, Hypersaline Mono Lake

Concentrations of viruses and prokaryotes in the alkaline, moderately hypersaline, seasonally stratified Mono Lake are among the highest reported for a natural aquatic environment. We used electron microscopy to test whether viral morphological characteristics differed among the epilimnion, metalimnion, and the anoxic hypolimnion of the lake and to determine how the properties of viruses in Mono Lake compare to other aquatic environments. Viral capsid size distributions were more similar in the metalimnion and hypolimnion of Mono Lake, while viral tail lengths were more similar in the epilimnion and metalimnion. The percentage of tailed viruses decreased with depth and the relative percentages of tailed phage families changed with depth. The presence of large (>125 nm capsid), untailed viruses in the metalimnion and hypolimnion suggests that eukaryotic viruses are produced in these suboxic and anoxic, hypersaline environments. Capsid diameters of viruses were larger on average in Mono Lake compared to other aquatic environments, and no lemon-shaped or filamentous viruses were found, in contrast to other high-salinity or high-altitude lakes and seas. Our data suggest that the physically and chemically distinct layers of Mono Lake harbor different viral assemblages, and that these assemblages are distinct from other aquatic environments that have been studied. Furthermore, we found that filtration of a sample through a 0.22-μm pore-size filter significantly altered the distribution of viral capsid diameters and tail lengths, resulting in a relative depletion of viruses having larger capsids and longer tails. This observation highlights the potential for bias in molecular surveys of viral diversity, which typically rely on filtration through 0.2- or 0.22-μm pore-size membrane filters to remove bacteria during sample preparation.     

Analysis of methane monooxygenase genes in mono lake suggests that increased methane oxidation activity may correlate with a change in methanotroph community structure

Mono Lake is an alkaline hypersaline lake that supports high methane oxidation rates. Retrieved pmoA sequences showed a broad diversity of aerobic methane oxidizers including the type I methanotrophs Methylobacter (the dominant genus), Methylomicrobium, and Methylothermus, and the type II methanotroph Methylocystis. Stratification of Mono Lake resulted in variation of aerobic methane oxidation rates with depth. Methanotroph diversity as determined by analysis of pmoA using new denaturing gradient gel electrophoresis primers suggested that variations in methane oxidation activity may correlate with changes in methanotroph community composition.     

Are Antarctic aquatic invertebrates hitchhiking on your footwear?

The increasing number of humans who travel to and within Antarctic regions each year not only increases the risk of introducing non-native species but also of translocating native species within and between Antarctic biogeoregions and poses the potential for artificial, human-mediated introduction of native freshwater invertebrate species to newly ice-free areas of Antarctica. This study was designed to test the potential for transfer of native Antarctic freshwater invertebrates and their cysts on footwear. An average of 1.86 Anostraca cysts, 29.47 Copepoda cysts, 4.29 Nematoda, 0.40 Rotifera and 0.966 Tardigrada individuals per gram of sediment were found in samples taken from footwear after contact with freshwater sediment. The invertebrate cysts isolated from the samples that underwent drying at 27 °C were able to hatch in tap water, and representatives of the other systematic groups (Nematoda, Rotifera, and Tardigrada) also remained viable.     

Aggression in closely related Malawi cichlids varies inversely with habitat complexity

Within the past 2 million years, the cichlids of Lake Malawi have diversified into well over 500 species resulting in one of the worlds largest lacustrine fish radiations. As a result, many of the habitats within the lake support a high diversity of species. In these highly species rich communities, male cichlids must acquire and defend a territory to successfully reproduce. Within the rock-dwelling cichlids of Lake Malawi (mbuna), this has resulted in the formation of polyspecific leks on the heterogeneous rocky benthos. Aggression is fairly common in these leks and has been tied not only to individual reproduction but to the larger phenomenon of community assembly and the maintenance of biological diversity. In this study, I examined the patterns of aggressive acts of four species within the mbuna genus Maylandia at two locations in the southern Lake Malawi. The number of aggressive acts of two sympatric species was examined at each location. At each site, one species defends territories over bedrock and the other over cobble. The number of aggressive acts across the four species was compared. The influence of habitat type on male aggression was examined and the targets of male aggression were identified to evaluate several hypotheses concerning the evolution of male aggression. The results show that aggression quantitatively varied among species, was largely directed towards heterospecifics, and was strongly influenced by habitat type. The aggressive behavior of one sympatric species pair, Maylandia benetos and Maylandia zebra, was observed under controlled laboratory conditions. Laboratory results support field observations: the bedrock associated species performed more aggressive acts and aggressive acts were directed equally at con- and heterospecifics. The results of this study suggest that habitat complexity plays a larger role in shaping aggressive behavior than other suggested factors such as competition for resources.     

Analysis of Methane Monooxygenase Genes in Mono Lake Suggests That Increased Methane Oxidation Activity May Correlate with a Change in Methanotroph Community Structure

Mono Lake is an alkaline hypersaline lake that supports high methane oxidation rates. Retrieved pmoA sequences showed a broad diversity of aerobic methane oxidizers including the type I methanotrophs Methylobacter (the dominant genus), Methylomicrobium, and Methylothermus, and the type II methanotroph Methylocystis. Stratification of Mono Lake resulted in variation of aerobic methane oxidation rates with depth. Methanotroph diversity as determined by analysis of pmoA using new denaturing gradient gel electrophoresis primers suggested that variations in methane oxidation activity may correlate with changes in methanotroph community composition.     

Patterns in the distribution of Arctic freshwater zooplankton related to glaciation history

We analysed circumpolar samples from 68 lakes within the 10°C-July isotherm from Arctic Canada, Nunavut, Greenland, Svalbard, Eastern Siberia, the Beringia region, and Alaska. In total, we found 3 species of Anostraca, 17 of Diplostraca, 1 species of cyclopoid and 14 species of calanoid copepods. Our study identifies a wider distribution for some copepods—e.g. Eurytemora pacifica, Leptodiaptomus sicilis, Arctodiaptomus novosibiricus, Cyclops abyssorum—than previously known. Moreover, one anostracan species, Artemiopsis bungei, was recorded in North America for the first time; and one chydoriid, Chydorus gibbus, is a new species for Greenland. We observed that species richness of crustaceans is lower in lakes that were glaciated during the Quaternary period, compared to those not glaciated (e.g. Chukotski Peninsula, Siberia; Point Barrow, Alaska; and Disko Island, Greenland). This confirms the findings of classic studies: glaciation has strongly affected the biogeography of freshwater crustaceans in circumpolar areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.