In marine environments Ostracoda and Foraminifera have been very successful invaders. During the ... more In marine environments Ostracoda and Foraminifera have been very successful invaders. During the Phanerozoic they colonised the majority of shallow, marginal to deep water, fully marine habitats. Both groups had developed physiological adaptations which pre-adapted them to the invasion of new marine habitats. They adopted a broad range of feeding strategies and reproduction modes. The production of resting stages and brood care may also have contributed to them being efficient invaders. They are also both highly tolerant to variations in salinity. The first invasions of non-marine habitats by ostracods appear to have taken place at the turn of the Devonian and Carboniferous. It is estimated that there had been between 9 and 12 independent invasions of fresh waters by the ostracods. In contrast Foraminifera are typically marine organisms, and only a few species of agglutinated and organic-walled Foraminifera are to be found in brackish and freshwater environments. Agglutinated species build their test using ambient components but are not commonly regarded as calcifying organisms. An impact of salinity on foraminiferal calcification has been observed in several studies. It seems that Foraminifera are incapable of constructing a fully calcified test in low salinity regimes; they use sea water not only as a source of ions to construct shell, but also as a biomineralisation solution. Thus, the success of ostracods in invading freshwater habitats can be attributed to their development of a more effective mechanism of calcification in low mineralisation waters. The core question of this study is to examine possible causes for the differences in success between the two taxa.
Novel faunistic data are presented from the poorly explored area of northern Lapland and comparis... more Novel faunistic data are presented from the poorly explored area of northern Lapland and comparisons are made between the present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream, and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and the littoral zone of lakes. In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different, as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes). Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites. The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland. Possible factors influencing this shift are discussed.
In this study, we compared the ostracod species diversity in selected inland-water habitats
of La... more In this study, we compared the ostracod species diversity in selected inland-water habitats of Lapland and Poland, and assessed the relationships between ostracod occurrence and abiotic environmental variables. In total, 41 species were collected, of which only 15 species were found in Lapland, as compared with 35 in Poland. Almost all species collected from the Lapland sites were eurybiontic and no clear differences were found between ostracod assemblages inhabiting different habitat types. We hypothesize that this homogeneity might be a consequence of the raised water level during the springtime snow melt, temporarily connecting various waterbodies. The main factors limiting distribution of ostracod species in Lapland appeared to be low pH and low ionic content of water. In Poland, predominantly stenobiontic species were observed. In temporary waters and peat-bogs of this area useful indicator species were identified.
The earliest freshwater colonisation by marine ostracods probably took place in the early Carboni... more The earliest freshwater colonisation by marine ostracods probably took place in the early Carboniferous. The first low salinity habitats invaded by ostracods were likely ephemeral ponds near the shoreline, or fluvial, deltaic settings influenced by marine transgression events. The dominant factor in such environments is rapid change in salinity resulting from fluctuations in sea level, evaporation and precipitation, so the first freshwater colonisers are likely to have been tolerant euryhaline species. The most obvious adaptation to such environments is tolerance to low salinity conditions. Modern studies report that ostracods possess efficient osmoregulatory mechanisms and are characterised by wide tolerance to different salinity regimes. They also exhibit other characteristics such as mixing reproductive mode, resting and/or desiccation-resistant eggs, and brood care which may facilitate colonisation of different regimes. Ostracods possess a calcified carapace containing high concentrations of calcium carbonate but shell formation may be less effective in poorly mineralised fresh waters. However, the mineral content of early Carboniferous coastal ponds was most probably sufficient to allow the development of calcified carapaces by the first freshwater species.
Distribution of ostracods in short sediment cores from the profundal-sublittoral zones of various... more Distribution of ostracods in short sediment cores from the profundal-sublittoral zones of various basins of Wdzydze lakes (N Poland), differing in trophic conditions, indicates three major assemblage types. In slightly eutrophic basins ostracod assemblages were dominated by Candona neglecta accompanied by Cytherissa lacustris, indicative of low trophy conditions. Increasing abundance of Candona candida, other candonids and nektobenthic eurytopic species, and gradual decline of C. lacustris corresponded with eutrophic conditions prevailing in most of the deepest basins. Finally, highly eutrophic basins were characterised by increasing abundance of nektobenthic species, decrease of. C. candida and complete disappearance of typically profundal, poly-oxyphilic species.
The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are descri... more The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are described from material collected from marine ranched Korean rockfish, Sebastes schlegelii. In L. elegans, setal number on the proximal segment of the antennule increases from 3 in the copepodid to 27 in the adult. Using the number of setae as a stage marker supports the inference that the post-naupliar phase of the life cycle comprises six stages: copepodid, chalimus I, chalimus II, pre-adult I, pre-adult II, and the adult. We observed variation in body length in both of the chalimus stages which we consider represents an early expression of sexual size dimorphism. We interpret the larger specimens of chalimus I as putative females, and the smaller as putative males; similarly with chalimus II, larger specimens are putative females and the smaller are males. Two patterns of life cycle are currently recognized within the Caligidae but the evidence presented here reconciles the two. We conclude that the typical caligid life cycle comprises only eight stages: two naupliar, one copepodid, and four chalimus stages preceding the adult in Caligus, but with the four chalimus stages represented by two chalimus and two pre-adult stages in Lepeophtheirus. This is a profound change with significant implications for the aquaculture industry, given that lice monitoring protocols include counts of chalimus stages and use temperature to predict when they will moult into the more pathogenic, mobile pre-adults. Lice management strategies must be tailored to the precise life cycle of the parasite.
Annales De Limnologie-international Journal of Limnology, 2010
Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide... more Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide the first record of these crustaceans from Finland north of the Arctic Circle. From a total of 35 sites visited, 14 species were collected, out of which four appeared to be new to Finland: Fabaeformiscandona lapponica, Pseudocandona pratensis, Eucypris pigra and Paralimnocythere relicta. Two major assemblage groups were recognised by clustering classification and multi-dimensional scaling ordination, one dominated by Cyclocypris ovum, the second by Candona candida. Taxonomic diversity of the most assemblages was of expected range based on the inventory of 53 freshwater species of Finland.
The extant genera of the ostracod family Thaumatocyprididae are revised using the results of a ph... more The extant genera of the ostracod family Thaumatocyprididae are revised using the results of a phylogenetic analysis based on 54 morphological characters and 28 taxa. This revealed two main lineages within the family. There is a deep-sea lineage comprising the two species of Thaumatocypris Müller, 1906, the thirteen species of Thaumatoconcha Kornicker and Sohn, 1976 and a monotypic Danielopolina Kornicker and Sohn, 1976, comprising the type species D. carolynae Kornicker and Sohn, 1976 only. The second lineage contained cave taxa only, all formerly placed in Danielopolina but here transferred to the subgenus Danielopolina (Humphreysella) Kornicker and Danielopol, in Kornicker et al., 2006, which is raised to full genus status as Humphreysella Kornicker and Danielopol, in Kornicker et al., 2006. This accommodates H.
orghidani (Danielopol, 1972) new combination, H. bahamensis (Kornicker and Iliffe, 1989a) new combination,
H. baltanasi (Kornicker in Humphreys et al., 2009) new combination, H. elizabethae (Kornicker and Iliffe, 1992) new combination, H. exuma (Kornicker and Iliffe, 1998) new combination, H. kakuki (Kornicker and Iliffe, 2000) new combination, H. mexicana (Kornicker and Iliffe, 1989a) new combination, H. palmeri (Kornicker et al., 2007) new combination, H. phalanx (Kornicker and Iliffe, 1995) new combination, H. styx (Kornicker and Iliffe, 1989c) new combination and H. wilkensi (Hartmann, 1985) new combination.
The position of the remaining species, Danielopolina kornickeri Danielopol et al., 2000, in phylogenetic
analyses is unstable, but this species is here recognised as a distinct lineage within the family. A new genus Welesina is established to accommodate as its type species Welesina kornickeri (Danielopol et al., 2000) new combination. New diagnoses are provided for all five genera. A new species of Thaumatoconcha, T. angeli sp. nov., is described, based on material of both sexes collected from deep water in the North Atlantic, on the Iberian abyssal plain. It can be readily distinguished from its congeners by the presence
of 2 small bristles on the compound third-fourth antennulary segment of the female, and by the setation
of the third endopodal segment of the antenna of the female.
In marine environments Ostracoda and Foraminifera have been very successful invaders. During the ... more In marine environments Ostracoda and Foraminifera have been very successful invaders. During the Phanerozoic they colonised the majority of shallow, marginal to deep water, fully marine habitats. Both groups had developed physiological adaptations which pre-adapted them to the invasion of new marine habitats. They adopted a broad range of feeding strategies and reproduction modes. The production of resting stages and brood care may also have contributed to them being efficient invaders. They are also both highly tolerant to variations in salinity. The first invasions of non-marine habitats by ostracods appear to have taken place at the turn of the Devonian and Carboniferous. It is estimated that there had been between 9 and 12 independent invasions of fresh waters by the ostracods. In contrast Foraminifera are typically marine organisms, and only a few species of agglutinated and organic-walled Foraminifera are to be found in brackish and freshwater environments. Agglutinated species build their test using ambient components but are not commonly regarded as calcifying organisms. An impact of salinity on foraminiferal calcification has been observed in several studies. It seems that Foraminifera are incapable of constructing a fully calcified test in low salinity regimes; they use sea water not only as a source of ions to construct shell, but also as a biomineralisation solution. Thus, the success of ostracods in invading freshwater habitats can be attributed to their development of a more effective mechanism of calcification in low mineralisation waters. The core question of this study is to examine possible causes for the differences in success between the two taxa.
Novel faunistic data are presented from the poorly explored area of northern Lapland and comparis... more Novel faunistic data are presented from the poorly explored area of northern Lapland and comparisons are made between the present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream, and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and the littoral zone of lakes. In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different, as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes). Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites. The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland. Possible factors influencing this shift are discussed.
In this study, we compared the ostracod species diversity in selected inland-water habitats
of La... more In this study, we compared the ostracod species diversity in selected inland-water habitats of Lapland and Poland, and assessed the relationships between ostracod occurrence and abiotic environmental variables. In total, 41 species were collected, of which only 15 species were found in Lapland, as compared with 35 in Poland. Almost all species collected from the Lapland sites were eurybiontic and no clear differences were found between ostracod assemblages inhabiting different habitat types. We hypothesize that this homogeneity might be a consequence of the raised water level during the springtime snow melt, temporarily connecting various waterbodies. The main factors limiting distribution of ostracod species in Lapland appeared to be low pH and low ionic content of water. In Poland, predominantly stenobiontic species were observed. In temporary waters and peat-bogs of this area useful indicator species were identified.
The earliest freshwater colonisation by marine ostracods probably took place in the early Carboni... more The earliest freshwater colonisation by marine ostracods probably took place in the early Carboniferous. The first low salinity habitats invaded by ostracods were likely ephemeral ponds near the shoreline, or fluvial, deltaic settings influenced by marine transgression events. The dominant factor in such environments is rapid change in salinity resulting from fluctuations in sea level, evaporation and precipitation, so the first freshwater colonisers are likely to have been tolerant euryhaline species. The most obvious adaptation to such environments is tolerance to low salinity conditions. Modern studies report that ostracods possess efficient osmoregulatory mechanisms and are characterised by wide tolerance to different salinity regimes. They also exhibit other characteristics such as mixing reproductive mode, resting and/or desiccation-resistant eggs, and brood care which may facilitate colonisation of different regimes. Ostracods possess a calcified carapace containing high concentrations of calcium carbonate but shell formation may be less effective in poorly mineralised fresh waters. However, the mineral content of early Carboniferous coastal ponds was most probably sufficient to allow the development of calcified carapaces by the first freshwater species.
Distribution of ostracods in short sediment cores from the profundal-sublittoral zones of various... more Distribution of ostracods in short sediment cores from the profundal-sublittoral zones of various basins of Wdzydze lakes (N Poland), differing in trophic conditions, indicates three major assemblage types. In slightly eutrophic basins ostracod assemblages were dominated by Candona neglecta accompanied by Cytherissa lacustris, indicative of low trophy conditions. Increasing abundance of Candona candida, other candonids and nektobenthic eurytopic species, and gradual decline of C. lacustris corresponded with eutrophic conditions prevailing in most of the deepest basins. Finally, highly eutrophic basins were characterised by increasing abundance of nektobenthic species, decrease of. C. candida and complete disappearance of typically profundal, poly-oxyphilic species.
The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are descri... more The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are described from material collected from marine ranched Korean rockfish, Sebastes schlegelii. In L. elegans, setal number on the proximal segment of the antennule increases from 3 in the copepodid to 27 in the adult. Using the number of setae as a stage marker supports the inference that the post-naupliar phase of the life cycle comprises six stages: copepodid, chalimus I, chalimus II, pre-adult I, pre-adult II, and the adult. We observed variation in body length in both of the chalimus stages which we consider represents an early expression of sexual size dimorphism. We interpret the larger specimens of chalimus I as putative females, and the smaller as putative males; similarly with chalimus II, larger specimens are putative females and the smaller are males. Two patterns of life cycle are currently recognized within the Caligidae but the evidence presented here reconciles the two. We conclude that the typical caligid life cycle comprises only eight stages: two naupliar, one copepodid, and four chalimus stages preceding the adult in Caligus, but with the four chalimus stages represented by two chalimus and two pre-adult stages in Lepeophtheirus. This is a profound change with significant implications for the aquaculture industry, given that lice monitoring protocols include counts of chalimus stages and use temperature to predict when they will moult into the more pathogenic, mobile pre-adults. Lice management strategies must be tailored to the precise life cycle of the parasite.
Annales De Limnologie-international Journal of Limnology, 2010
Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide... more Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide the first record of these crustaceans from Finland north of the Arctic Circle. From a total of 35 sites visited, 14 species were collected, out of which four appeared to be new to Finland: Fabaeformiscandona lapponica, Pseudocandona pratensis, Eucypris pigra and Paralimnocythere relicta. Two major assemblage groups were recognised by clustering classification and multi-dimensional scaling ordination, one dominated by Cyclocypris ovum, the second by Candona candida. Taxonomic diversity of the most assemblages was of expected range based on the inventory of 53 freshwater species of Finland.
The extant genera of the ostracod family Thaumatocyprididae are revised using the results of a ph... more The extant genera of the ostracod family Thaumatocyprididae are revised using the results of a phylogenetic analysis based on 54 morphological characters and 28 taxa. This revealed two main lineages within the family. There is a deep-sea lineage comprising the two species of Thaumatocypris Müller, 1906, the thirteen species of Thaumatoconcha Kornicker and Sohn, 1976 and a monotypic Danielopolina Kornicker and Sohn, 1976, comprising the type species D. carolynae Kornicker and Sohn, 1976 only. The second lineage contained cave taxa only, all formerly placed in Danielopolina but here transferred to the subgenus Danielopolina (Humphreysella) Kornicker and Danielopol, in Kornicker et al., 2006, which is raised to full genus status as Humphreysella Kornicker and Danielopol, in Kornicker et al., 2006. This accommodates H.
orghidani (Danielopol, 1972) new combination, H. bahamensis (Kornicker and Iliffe, 1989a) new combination,
H. baltanasi (Kornicker in Humphreys et al., 2009) new combination, H. elizabethae (Kornicker and Iliffe, 1992) new combination, H. exuma (Kornicker and Iliffe, 1998) new combination, H. kakuki (Kornicker and Iliffe, 2000) new combination, H. mexicana (Kornicker and Iliffe, 1989a) new combination, H. palmeri (Kornicker et al., 2007) new combination, H. phalanx (Kornicker and Iliffe, 1995) new combination, H. styx (Kornicker and Iliffe, 1989c) new combination and H. wilkensi (Hartmann, 1985) new combination.
The position of the remaining species, Danielopolina kornickeri Danielopol et al., 2000, in phylogenetic
analyses is unstable, but this species is here recognised as a distinct lineage within the family. A new genus Welesina is established to accommodate as its type species Welesina kornickeri (Danielopol et al., 2000) new combination. New diagnoses are provided for all five genera. A new species of Thaumatoconcha, T. angeli sp. nov., is described, based on material of both sexes collected from deep water in the North Atlantic, on the Iberian abyssal plain. It can be readily distinguished from its congeners by the presence
of 2 small bristles on the compound third-fourth antennulary segment of the female, and by the setation
of the third endopodal segment of the antenna of the female.
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Papers by Anna Iglikowska
They adopted a broad range of feeding strategies and reproduction modes. The production of resting stages and brood care may also have contributed to them being efficient invaders. They are also both highly tolerant to variations in salinity. The first invasions of non-marine habitats by ostracods appear to have taken place at the turn of the Devonian and Carboniferous. It is estimated that there had been between 9 and 12 independent invasions of fresh waters by the ostracods. In contrast Foraminifera are typically marine organisms, and only a few species of
agglutinated and organic-walled Foraminifera are to be found in brackish and freshwater environments. Agglutinated species build their test using ambient
components but are not commonly regarded as calcifying organisms. An impact of salinity on foraminiferal calcification has been observed in several studies. It seems
that Foraminifera are incapable of constructing a fully calcified test in low salinity regimes; they use sea water not only as a source of ions to construct shell, but also
as a biomineralisation solution. Thus, the success of ostracods in invading freshwater habitats can be attributed to their development of a more effective mechanism
of calcification in low mineralisation waters. The core question of this study is to examine possible causes for the differences in success between the two taxa.
present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and
Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream,
and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were
mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and
the littoral zone of lakes.
In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris
ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least
abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different,
as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes).
Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three
characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when
grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between
the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites.
The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century
seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland.
Possible factors influencing this shift are discussed.
of Lapland and Poland, and assessed the relationships between ostracod occurrence
and abiotic environmental variables. In total, 41 species were collected, of which
only 15 species were found in Lapland, as compared with 35 in Poland. Almost all species
collected from the Lapland sites were eurybiontic and no clear differences were
found between ostracod assemblages inhabiting different habitat types. We hypothesize
that this homogeneity might be a consequence of the raised water level during the
springtime snow melt, temporarily connecting various waterbodies. The main factors
limiting distribution of ostracod species in Lapland appeared to be low pH and low
ionic content of water. In Poland, predominantly stenobiontic species were observed.
In temporary waters and peat-bogs of this area useful indicator species were identified.
orghidani (Danielopol, 1972) new combination, H. bahamensis (Kornicker and Iliffe, 1989a) new combination,
H. baltanasi (Kornicker in Humphreys et al., 2009) new combination, H. elizabethae (Kornicker and Iliffe, 1992) new combination, H. exuma (Kornicker and Iliffe, 1998) new combination, H. kakuki (Kornicker and Iliffe, 2000) new combination, H. mexicana (Kornicker and Iliffe, 1989a) new combination, H. palmeri (Kornicker et al., 2007) new combination, H. phalanx (Kornicker and Iliffe, 1995) new combination, H. styx (Kornicker and Iliffe, 1989c) new combination and H. wilkensi (Hartmann, 1985) new combination.
The position of the remaining species, Danielopolina kornickeri Danielopol et al., 2000, in phylogenetic
analyses is unstable, but this species is here recognised as a distinct lineage within the family. A new genus Welesina is established to accommodate as its type species Welesina kornickeri (Danielopol et al., 2000) new combination. New diagnoses are provided for all five genera. A new species of Thaumatoconcha, T. angeli sp. nov., is described, based on material of both sexes collected from deep water in the North Atlantic, on the Iberian abyssal plain. It can be readily distinguished from its congeners by the presence
of 2 small bristles on the compound third-fourth antennulary segment of the female, and by the setation
of the third endopodal segment of the antenna of the female.
They adopted a broad range of feeding strategies and reproduction modes. The production of resting stages and brood care may also have contributed to them being efficient invaders. They are also both highly tolerant to variations in salinity. The first invasions of non-marine habitats by ostracods appear to have taken place at the turn of the Devonian and Carboniferous. It is estimated that there had been between 9 and 12 independent invasions of fresh waters by the ostracods. In contrast Foraminifera are typically marine organisms, and only a few species of
agglutinated and organic-walled Foraminifera are to be found in brackish and freshwater environments. Agglutinated species build their test using ambient
components but are not commonly regarded as calcifying organisms. An impact of salinity on foraminiferal calcification has been observed in several studies. It seems
that Foraminifera are incapable of constructing a fully calcified test in low salinity regimes; they use sea water not only as a source of ions to construct shell, but also
as a biomineralisation solution. Thus, the success of ostracods in invading freshwater habitats can be attributed to their development of a more effective mechanism
of calcification in low mineralisation waters. The core question of this study is to examine possible causes for the differences in success between the two taxa.
present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and
Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream,
and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were
mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and
the littoral zone of lakes.
In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris
ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least
abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different,
as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes).
Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three
characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when
grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between
the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites.
The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century
seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland.
Possible factors influencing this shift are discussed.
of Lapland and Poland, and assessed the relationships between ostracod occurrence
and abiotic environmental variables. In total, 41 species were collected, of which
only 15 species were found in Lapland, as compared with 35 in Poland. Almost all species
collected from the Lapland sites were eurybiontic and no clear differences were
found between ostracod assemblages inhabiting different habitat types. We hypothesize
that this homogeneity might be a consequence of the raised water level during the
springtime snow melt, temporarily connecting various waterbodies. The main factors
limiting distribution of ostracod species in Lapland appeared to be low pH and low
ionic content of water. In Poland, predominantly stenobiontic species were observed.
In temporary waters and peat-bogs of this area useful indicator species were identified.
orghidani (Danielopol, 1972) new combination, H. bahamensis (Kornicker and Iliffe, 1989a) new combination,
H. baltanasi (Kornicker in Humphreys et al., 2009) new combination, H. elizabethae (Kornicker and Iliffe, 1992) new combination, H. exuma (Kornicker and Iliffe, 1998) new combination, H. kakuki (Kornicker and Iliffe, 2000) new combination, H. mexicana (Kornicker and Iliffe, 1989a) new combination, H. palmeri (Kornicker et al., 2007) new combination, H. phalanx (Kornicker and Iliffe, 1995) new combination, H. styx (Kornicker and Iliffe, 1989c) new combination and H. wilkensi (Hartmann, 1985) new combination.
The position of the remaining species, Danielopolina kornickeri Danielopol et al., 2000, in phylogenetic
analyses is unstable, but this species is here recognised as a distinct lineage within the family. A new genus Welesina is established to accommodate as its type species Welesina kornickeri (Danielopol et al., 2000) new combination. New diagnoses are provided for all five genera. A new species of Thaumatoconcha, T. angeli sp. nov., is described, based on material of both sexes collected from deep water in the North Atlantic, on the Iberian abyssal plain. It can be readily distinguished from its congeners by the presence
of 2 small bristles on the compound third-fourth antennulary segment of the female, and by the setation
of the third endopodal segment of the antenna of the female.