What Does “ITS” Say about Hybridization in Lineages of <i>Sarsia</i> (Corynidae, Hydrozoa) from the White Sea?

Hydrozoans are widely known for their complex life cycles. The life cycle usually includes an asexual benthic polyp, which produces a sexual zooid (gonophore). Here, we performed an extensive analysis of 183 specimens of the hydrozoan genus Sarsia from the White Sea and identified four types of gonophores. We also compared the type of gonophore with haplotypes of the molecular markers COI and ITS. Analysis of COI sequences recovered that the studied specimens related to the species S. tubulosa, S. princeps and S. lovenii, and that the S. lovenii specimens divided into two COI haplogroups. More intraspecific genetic diversity was revealed in the analysis of the ITS sequences. The Sarsia tubulosa specimens divided into two ITS haplotypes, and presumably, hybrid forms between these lineages were found. For S. lovenii, we identified 14 ITS haplotypes as a result of allele separation. Intra-individual genetic polymorphism of the ITS region was most likely associated with intraspecific crossing between the different haplotypes. The diversity of the morphotypes was associated with the genetic diversity of the specimens. Thus, we demonstrated that the morphologically variable species S. lovenii is represented in the White Sea by a network of intensively hybridizing haplotypes. Hybridization affects the morphology and maturation period of gonophores and presumably affects the processes of speciation

Tab. 1: Chupa Inlet, Kandalaksha Bay of the White Sea. Population density of the dominant boreal copepod species and daily pellet carbon flux

Data on the zooplankton community structure, gut evacuation rate and carbon content of zooplankton faecal pellets were used for assessing the contribution of zooplankton to vertical carbon fluxes in the White and Kara Seas. The results revealed strong regional and seasonal variations of pellet carbon input related to differences in structure and dynamics of the zooplankton communities in the regions studied. In the deep regions of the White Sea, maximum daily pellet carbon flux from the 0-50 m layer was observed in the spring. It reached 98 mg Corg m-2 day-1 and coincided with a strong predominance of the large arctic herbivorous copepod Calanus glacialis in the surface layers. In summer and fall, it decreased by 1 to 2 orders of magnitude due to migration of this copepod to its overwintering depths. In contrast, in the shallow coastal regions, the pellet production was low in spring, gradually increased during summer and reached its maximum of 138 mg Corg m-2 day-1 by late summer to beginning of autumn. Such a seasonal pattern was in accordance with the seasonal variation of abundance of major pellet producers, the small boreal copepods Acartia bifilosa, Centropages hamatus, and Temora longicornis. In the estuarine zone of the Kara Sea, the pellet flux was mostly formed by pellets of brackish-water omnivorous copepods. It varied from 35 mg Corg m-2 day-1 in 1997 to 96 mg Corg m-2 day-1 in 1999. In the central Kara Sea with its typical marine community, the daily flux reached 125 mg Corg m-2 day-1 in summer. The results of our calculations indicate that both in the White and Kara seas zooplankton pellet carbon contributes up to 30 % to the total carbon flux during particular seasons

Dominant zooplankton species and microelements in plankton obtained from White Sea surface waters

Despite the fact that plankton plays an important role in biogeochemical processes in oceans, data on its elemental composition, particularly in shelf seas of the Arctic Ocean, have thus far been insufficient. This communication, which is devoted to a comparative analysis of the elemental composition of plankton and bottom sediments in the White Sea, is part of the comprehensive investigation of the region that is occurring in line with the International Project ''Land-Ocean Interaction in the Russian Arctic'' (LOIRA)

Green Fluorescence of <i>Cytaeis</i> Hydroids Living in Association with <i>Nassarius</i> Gastropods in the Red Sea

<div><p>Green Fluorescent Proteins (GFPs) have been reported from a wide diversity of medusae, but only a few observations of green fluorescence have been reported for hydroid colonies. In this study, we report on fluorescence displayed by hydroid polyps of the genus <i>Cytaeis</i> Eschscholtz, 1829 (Hydrozoa: Anthoathecata: Filifera) found at night time in the southern Red Sea (Saudi Arabia) living on shells of the gastropod <i>Nassarius margaritifer</i> (Dunker, 1847) (Neogastropoda: Buccinoidea: Nassariidae). We examined the fluorescence of these polyps and compare with previously reported data. Intensive green fluorescence with a spectral peak at 518 nm was detected in the hypostome of the <i>Cytaeis</i> polyps, unlike in previous reports that reported fluorescence either in the basal parts of polyps or in other locations on hydroid colonies. These results suggest that fluorescence may be widespread not only in medusae, but also in polyps, and also suggests that the patterns of fluorescence localization can vary in closely related species. The fluorescence of polyps may be potentially useful for field identification of cryptic species and study of geographical distributions of such hydroids and their hosts.</p></div

Maximum likelihood tree of 16S mitochondrial rRNA gene sequences from <i>Cytaeis</i>, <i>Podocorynoides</i>, and their closest relatives (BLAST similarity >90%).

<p><i>P</i>. <i>minima</i> from Mediterranean and New Zealand clusters within other representatives of the family Rathkeidae (<i>Rathkea</i> and <i>Lizzia</i>). The Red Sea <i>Cytaeis</i> sp clusters with the sequence of <i>Cytaeis</i> sp. (EU883541) from Japan and <i>Cytaeis capitata</i> from Indonesia. Schematic images of the polyps of <i>Cytaeis</i> sp. from Japan and the Red Sea indicate location of the fluorescence.</p

Microscopy imagery of fluorescence of hydroids (<i>Cytaeis</i> sp.) collected in the Saudi Arabian Red Sea.

<p>(A) green fluorescence of the polyps, scale bar 0.3 mm; (B) emission spectrum measured directly from fluorescent part of the polyp (red circle in the inset).</p

The sampling locality and study area in the Farasan Islands (Saudi Arabia), a complex of islands (indicated in green) in the southern Red Sea (inset).

<p>The red star indicates sampling locality within the Farasan Islands group. (The base geographic layer was downloaded from the Landsat 8 satellite database (<a href="http://libra.developmentseed.org/" target="_blank">http://libra.developmentseed.org</a>, Accessed 13 October 2015), via CC by 3.0 (<a href="https://creativecommons.org/licenses/by/3.0/" target="_blank">https://creativecommons.org/licenses/by/3.0/</a>)).</p