Branchipus Schaefferi Research Articles

Rediscovery of Branchipus schaefferi (Branchiopoda: Anostraca) in Belgium - notes on habitat requirements and conservation management

Fairy shrimps (Crustacea, Anostraca) are specialized inhabitants of inland water bodies that
 periodically dry or freeze over. Here we report the first observation since 1997 of a member of this basal crustacean order in Belgium and the first sighting of the species Branchipus schaefferi Fischer, 1834 since 1930. Nineteen populations were found in a restricted area located 55 km SE of Brussels in the Province of Hainaut. Based on a field survey, we discuss the habitat characteristics of these populations. We discuss also the distribution and habitat requirements of the species based on literature and formulate a number of guidelines for the conservation of this species as well as other large branchiopods in densely settled areas with intensive agriculture such as Belgium. Finally, we formulate a number of likely explanations for the lack of recent observations of these organisms in Western Europe and in Belgium.

Locomotor activity in Branchipus schaefferi (Fischer, 1834) (Branchiopoda: Anostraca) under thermal variation

The behavioral responses of Branchipus schaefferi Fisher, 1834 males and females to short-term thermal stress in six different rearing conditions are studied. The swimming performance was tested in pure tap water and water collected from both male and female culture mediums. The animal's behavior was recorded using a high-definition digital video camera mounted approximately 30 cm above the experimental containers. The swimming track and the thoracopod beating rates were recorded manually for each animal at different temperatures. The results indicate that in most cases, a significant increase in active swimming and limb beating rate occurred with increasing temperature. However, the animals tested in the different male and female culture medium were significantly less active compared to those in tap water, under similar thermal stress. Animals seem to produce substances in the culture media that influence their locomotor behavior under thermal stress.

Instances of erroneous DNA barcoding of metazoan invertebrates: Are universal cox1 gene primers too "universal"?

The cytochrome c oxidase subunit I (cox1) gene is the main mitochondrial molecular marker playing a pivotal role in phylogenetic research and is a crucial barcode sequence. Folmer’s “universal” primers designed to amplify this gene in metazoan invertebrates allowed quick and easy barcode and phylogenetic analysis. On the other hand, the increase in the number of studies on barcoding leads to more frequent publishing of incorrect sequences, due to amplification of non-target taxa, and insufficient analysis of the obtained sequences. Consequently, some sequences deposited in genetic databases are incorrectly described as obtained from invertebrates, while being in fact bacterial sequences. In our study, in which we used Folmer’s primers to amplify COI sequences of the crustacean fairy shrimp Branchipus schaefferi (Fischer 1834), we also obtained COI sequences of microbial contaminants from Aeromonas sp. However, when we searched the GenBank database for sequences closely matching these contaminations we found entries described as representatives of Gastrotricha and Mollusca. When these entries were compared with other sequences bearing the same names in the database, the genetic distance between the incorrect and correct sequences amplified from the same species was c.a. 65%. Although the responsibility for the correct molecular identification of species rests on researchers, the errors found in already published sequences data have not been re-evaluated so far. On the basis of the standard sampling technique we have estimated with 95% probability that the chances of finding incorrectly described metazoan sequences in the GenBank depend on the systematic group, and variety from less than 1% (Mollusca and Arthropoda) up to 6.9% (Gastrotricha). Consequently, the increasing popularity of DNA barcoding and metabarcoding analysis may lead to overestimation of species diversity. Finally, the study also discusses the sources of the problems with amplification of non-target sequences.

Larval identification of two syntopic species Branchipus schaefferi and Tanymastix stagnalis (Crustacea, Anostraca) sheds light on their pattern of coexistence

In the present study we applied a discriminant function analysis to distinguish two fairy shrimp species, Branchipus schaefferi and Tanymastix stagnalis (Anostraca), co-occurring in Lago dell’Orso in central Italy. Our aim was to obtain information on the pattern of coexistence of these two species to investigate their syntopy since early larval stages. To identify the larvae of the two species we used six discriminant functions, one for each larval stage considered (nauplius, four metanauplius stages and juvenis), and based on morphometric analyses and measurements of different traits (thoracic appendages, body length, length of first antenna, length of head, thorax length and length of furca). The pool was visited at weekly intervals during two time periods for a total of 4 years (1995–1996 and 2000–2001) and physical and chemical variables (water level, water and air temperature, pH and conductivity) were recorded. A total of 1067 specimens were collected, measured and morphometrically identified. B. schaefferi was more abundant and persistent than T. stagnalis. At any stage, T. stagnalis was bigger than B. schaefferi and this difference may justify niche differentiation between coexisting species. Difference in size might be linked to difference in life-span as B. schaefferi reproduced earlier and at a smaller size than T. stagnalis. When the hydroperiod is short, B. schaefferi might be the only species to produce resting eggs in time for reproduction. On the other hand, T. stagnalis may have an advantage in the longest hydroperiods. In an ephemeral seasonal pond such as Lago dell’Orso, coexistence can be fostered and competitive exclusion can be prevented as a result of seasonal environmental changes.

Risk reduction strategies in Branchipus schaefferi (Crustacea: Anostraca: Branchiopoda) as adaptation to a variable environment

Mud from a temporary pool in Morocco was sequentially inundated and dried at the laboratory to follow the life history of Branchipus schaefferi. Once adult, each female was coupled to a male in order to study their life history and reproduction. The average percentage of hatching decreased during the successive inundations, presumably as an adaptation to the unpredictability of the habitat. However, there was no indication that the offspring of the first inundation would preferentially hatch during their first inundation too, neither was there any such preference in the offspring of the delayed hatchings. Each female reduced risk by spreading hatching time of her resting eggs over consecutive inundations. Eggs did not hatch all at the same moment, reducing the chance that a female’s entire offspring would die before reaching maturity if the pool would dry out too soon. There was a significant difference between the mean value of the number of resting eggs produced by the females from a large clutch size, and those produced by females from a small clutch size. There thus appears to be a genetic base for the clutch size of females.

Relative scaling and colouration of cercopodes in Branchipus schaefferi (Crustacea: Branchiopoda)

AbstractIn the crustacean

Re-evaluation of three related species of the genus BranchipusSchaeffer, 1766 (Branchiopoda: Anostraca) by morphological and genetic analyses

The systematics of the genus Branchipus Schaeffer, 1766 (Branchiopoda: Anostraca) has been based on morphological taxonomy only and thus remains poorly resolved or, at best, questionable. Among the seven species described in the genus, a detailed comparison of Branchipus schaefferi Fischer, 1834 with both B. pasai Cottarelli, 1969 and B. visnyai Kertesz, 1956 is necessary to clarify their status. The use of morphological characters and, in particular, the appearance of second antennae and antennal appendages in males still cause taxonomic confusion among these three species. Herein, we use two molecular markers (allozymes and mtDNA sequences) and scanning electron microscopy to determine consistent differentiation patterns and test for congruence with the shape of the genus diagnostic trait, the frontal shield. We analyzed specimens belonging to 11 populations and covering a wide geographic distribution: B. pasai from Italy, B. schaefferi from Spain and Morocco, and B. visnyai from Malta and Italy. The extent of genetic divergence among populations evaluated by allozyme variation at 13 enzymatic loci and a mtDNA marker suggests the existence of different taxa and the absence of gene flow between them. The molecular results, together with morphological observations, did not provide support for the existing subdivision in the three nominal species B. pasai , B. schaefferi , and B. visnyai and places the validity of previously proposed taxonomic groups in discussion.

PERIODICKÉ TŮNĚ DOLNÍHO PODYJÍ

The qualitative composition and biology of aquatic invertebrates of the periodical pools of the lower Podyjí region is presented in the study. In the floodplains of south Moravia are many of vernal periodical pools with typical fauna e. g. Lepidurus apus, Eubranchipus grubii, Cyzicus tetracerus, Stygobromius ambulans, Hemidiaptomus amblyodon, Mixodiaptomus kupelwieseri, Diaptomus castor. Periodical vernal poools emerge after snow thawing, rains or floods. The summer periodical pools are at lower reaches of the Dyje River very rare. In this sort of pools live e. g. Triops cancriformis, Branchipus schaefferi, Leptestheria dahalacensis, larvae of mosquito Aedes vexans, Anopheles maculipennis, Culiseta annulata. The presented data may be avalaible for comparative study in the future with respect to expected global climate changes.

On some morphological abnormalities in adult fairy shrimp Branchipus schaefferi Fischer, 1834, from Serbia

Branchipus schaefferi Fischer, 1834, is a common and one of the most abundant large branchiopods widely distributed in Europe. In this work, for the first time, we describe and classify some of the most frequently observed morphological anomalies in this species. These are deformities in the head structures as well as in cercopods. Possible causes of such anomalities are discussed in detail.

Karyotypes and Sex Ratios in Populations of Eubranchipus Grubii (Dybowski, 1860) and Branchipus Schaefferi Fischer, 1834 (Branchiopoda, Anostraca) from Poland

Two populations of the fairy shrimp Eubranchipus grubii (Dybowski, 1860) and one population of Branchipus schaefferi Fischer, 1834 from Poland were studied cytogenetically. The aim was to confirm their diploid chromosome numbers and chromosome morphology, as well as to reveal the distribution of nucleolar organizer regions (NORs) and the course of meiosis. The first species exhibited 24 small chromosomes in both sexes, while the latter showed 2n = 20 in both males and females. In E. grubii, female meiosis involved a “diffuse stage” characterized by decondensation of chromatin, and positive heteropycnosis (after staining by Giemsa) of one bivalent. The morphology of the plates of the second meiotic division suggests the chromosomes in both species are monocentric (prevailingly bi-armed). Nevertheless, constitutive heterochromatin has not been visualized by C-banding. Silver staining revealed 3 pairs of nucleolar organizer regions (NOR) in B. schaefferi, while in E. grubii the detection of NORs failed. In contrast to some previous studies reporting supernumerary chromosomes (B chromosomes) as sex ratio distorters in B. schaefferi, we failed to observe any B chromosomes in the populations under study. We suggest the fluctuation of sex ratios as found in the local populations, would rather be influenced by the environment.

Assemblage structure and dynamics of large branchiopods in Mediterranean temporary wetlands: patterns and processes

Summary1. To monitor the diversity and distribution patterns of large branchiopods and the effects of local and regional processes, 30 temporary wetlands in a nature reserve in the Camargue (southern France) were sampled and characterised during three consecutive inundations (2005–08). Additional species were added to the list for each wetland by hatching animals from the resting egg bank, after determining the optimal hatching conditions.2. A total of five species were found, representing 28% of the species known in France and 56% of the known Camargue species. Tanymastix stagnalis, Branchipus schaefferi, Chirocephalus diaphanus (Anostraca), Triops cancriformis (Notostraca) and Imnadia yeyetta (Spinicaudata) were distributed over a total of 19 wetlands.3. More than one species was present in 79% of the wetlands containing large branchiopods. Individual wetlands harboured on average 2.8 species, with a maximum of five coexisting species. Large branchiopod assemblages were temporally variable, differing among the three inundations with different climatological conditions.4. The most important habitat factor influencing the distribution of large branchiopods was salinity, adversely affecting the density and survival of hatchlings. The persistence of large branchiopods in these temporary waters may be threatened by increasing salinisation driven by intensive water management and climate change.

Diaspore Dispersal of Anostraca by Flying Insects

Fairy shrimps (Anostraca) live in temporary waters. Dominant among their predators are aquatic insects, especially diving beetles (Dytiscidae). Mastication of the eggs of the fairy shrimp Branchipus schaefferi and their passage through the digestive tract of smaller beetles, like Ilybius fenestratus, has a positive effect on hatching afterwards. Dytiscidae could be important vectors for aerial dispersal of diaspores among ponds which are not directly connected to a stream channel. Such long-distance dispersal can be of critical importance for population survival and gene flow among communities living in temporary habitats.

Biochemical and biophysical aspects of the tolerance of anhydrobiotic crustacean embryos to very high temperatures

1. Heat tolerance of dry cysts of the fairy shrimp Branchipus schaefferi and the brine shrimp, Artemia franciscana was studied using rapid (∼100 °C/min) and slow (∼4 °C/min) heating. 2. Rapid heating caused much greater death than did slow, and we consider the possible causes. 3. Although these primitive crustaceans are closely related, the major stress proteins of Artemia cysts (artemin and p26) were not detected in Branchipus cysts. 4. The Arrhenius activation energy ( E a) for thermal killing of Branchipus cysts was found to be 5-fold higher than that of Artemia cysts over the range of 110–130 °C. 5. These major differences in stress proteins and E a are especially interesting because the thermal tolerance of both kinds of cysts is very similar.

Pheromones inhibit the hatching of diapausing Anostraca (Crustacea: Branchiopoda)

Abstract Hatching of resting eggs of Streptocephalus torvicornis (Waga, 1942) and Branchipus schaefferi Fischer, 1834, two sympatric fairy shrimps, was tested using medium in which these two species and Chirocephalus diaphanus (Prévost, 1803) had been raised. The medium of adults inhibited the hatching of conspecific nauplii, even when diluted by 50% using distilled water. Streptocephalus torvicornis resting eggs hatch in the medium of C. diaphanus but not in the medium of B. schaefferi. Resting eggs of B. schaefferi hatched in low numbers in S. torvicornis medium, and in high numbers in that of C. diaphanus.There appears to be one or more substances associated with the presence of adults of conspecifics and sympatrics which exceed the influences of abiotic factors, such as light, pH, conductivity and osmotic pressure in fresh media. We propose that this substance(s) functions as a pheromone to inhibit further hatching once a population of adults is present.

Life cycle and genetic differences of two Branchipus schaefferi populations from Morocco (Anostraca: Crustacea)

AbstractThe somatic growth, longevity, and reproduction of two Moroccan anostracan populations from different climatic areas were studied under standardized laboratory conditions. Both populations were subjected to allozyme analyses covering four loci, and molecular analyses of the variable regions, the Internal Transcribed Spacers (ITS1 & ITS2) intervening the nuclear ribosomal genes (18S, 5.8S, 28S rDNA). The ecological characteristics of the life cycle of each population are presented, together with their genetic differences and phylogenetic relationships.

DIFFERENT LIFE HISTORIES OF THE CO-OCCURRING FAIRY SHRIMPS BRANCHIPUS SCHAEFFERI AND STREPTOCEPHALUS TORVICORNIS (ANOSTRACA)

Abstract Branchipus schaefferi and Streptocephalus torvicornis commonly co-occur in ephemeral ponds throughout the Mediterranean Region. We compared survivorship, growth, and reproduction. Our results show statistically significant differences in all three parameters under laboratory conditions at 25°C, reflecting different life history strategies between these species. Branchipus schaefferi grows quickly to 18 mm body length, producing roughly 1700 cysts during an average lifespan of 24 days, while S. torvicornis lives an average of 120 days (length 24 mm), laying 2400 cysts. This suggests that S. torvicornis is better adapted to deep longer-lived pools, whereas B. schaefferi may survive in small, more ephemeral pools as formed from spring melt water and autumn rains. While the lifespan is equal for both sexes in B. schaefferi, the males of S. torvicornis live 2.8 times longer than females (325 days versus 114) compelled into a long postreproductive period by lack of females in their environment.

B-chromosomes and male-biased sex ratio with paternal inheritance in the fairy shrimp Branchipus schaefferi (Crustacea, Anostraca).

This study reports on male-biased sex ratios in west Mediterranean populations of the freshwater anostracan Branchipus schaefferi (Crustacea, Anostraca, Branchipodidae), in contrast to populations elsewhere. Crossing experiments over several generations indicate a clear paternal inheritance of the trait, possibly with a dosage effect. Various mechanisms which may underlie this phenomenon are discussed, the most plausible being the presence of one or more supernumerary ('B') chromosomes--as evidenced by karyological observations--interfering with sex determination and probably having an accumulation mechanism in male individuals.

Updating Anostraca (Crustacea, Branchiopoda) distribution in Italy

In this note recent records of some Anostraca species in Italy are presented. These data widen the known distribution in Italy of Branchipus schaefferi Fischer, 1834, Tanymastix stagnalis Linnaeus, 1758, Chirocephalus ruffoi Cottarelli & Mura, 1984 and Branchinella spinosa Milne-Edwards, 1840, and illustrate the problem of inadequate knowledge of our territory, at least as far as Anostraca (Branchiopoda) are concerned.

Further evidence of the synonymy between Branchipus schaefferi and B. visnyai (Crustacea, Anostraca)

In this study, the systematic position of Branchipus visnyai, recently put into discussion by previous Authors on the basis of merely morphological characters, is reconsidered. The comparison of electrophoretic allozyme patterns between two natural populations of B. visnyai and B. schaefferi from central Italy revealed a very high genetic identity. Thus, the use of allozymic analysis, only rarely applied to Anostraca, indicates that the separation of B. visnyai from B. schaefferi as a distinct species is unfounded.

Aeromonas hydrophila causes 'black disease' in fairy shrimps (Anostraca; Crustacea).

A total of 51 bacterial strains were isolated from fairy shrimps [Branchipus schaefferi (Fisher), Chirocephalus diaphanus (Prévost) and Streptocephalus torvicornis (Waga)] showing signs of 'black disease'. The fairy shrimps showed black nodules on the thoracic appendages, the cercopods, the antennae and sometimes at the back of the head. The infection sites on the thoracic appendages were restricted to the proximal parts of the endopodite, the exopodite and endite I. In order to check Koch's postulates, pure bacterial cultures were administered to healthy fairy shrimps. One bacterial pathogen was identified as Aeromonas hydrophila using BIOLOG and the genotypic fingerprinting technique AFLP.