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![A C. connivens specimen from the Vistula Lagoon. 1 – an internode of the main axis (stem), usually longer than branchlets; 2 – an incurved sterile branchlet. The specimen’s thalli are delicately green and lustrous as described by Dąmbska [4].](profile/Adam-Wozniczka-2/publication/274641825/figure/fig2/AS:294721294487565@1447278440307/A-C-connivens-specimen-from-the-Vistula-Lagoon-1-an-internode-of-the-main-axis.png)
A C. connivens specimen from the Vistula Lagoon. 1 – an internode of the main axis (stem), usually longer than branchlets; 2 – an incurved sterile branchlet. The specimen’s thalli are delicately green and lustrous as described by Dąmbska [4].
Source publication
The stonewort Chara connivens was rediscovered in the Vistula Lagoon in 2011, almost 35 years after its last record. In 2012, the species was recorded for the first time in the Szczecin Lagoon. Chara connivens occurred at shallow (0.5–1.2 m) sandy-muddy and muddy bottoms of small embayments. In the Vistula Lagoon, the stonewort was represented by s...
Contexts in source publication
Context 1
... are a group of macroscopic green algae represented by 314 species [1] assigned to the family Chara- ceae within the phylum Chlorophyta; alternatively, they are treated as a separate phylum, the Charophyta [2]. The occurrence of most of the Characeae species in Europe is limited to clear, freshwater lakes of low fertility [3–8]. In response to increasing trophic status and the associated light limitation, many charophytes have therefore become rare, and are treated as sensitive bioindicators of water quality [6,9]. Although the number of sites with abundant charophyte vegetation has decreased, these macroalgae are widely distributed in different types of aquatic environments throughout the world. Due to their ability for ion regula- tion and osmotic adjustment, a set of charophyte species, commonly known from freshwaters, can occur in brackish coastal lagoons, as shown for the Baltic Sea [10]. In brackish waters, charophytes experience changes in osmotic pressure and mineral composition [7]. A brackish environment unique on a global scale is the Baltic Sea, the world’s largest brackish water body [11]. The variety of the Baltic coast types gives rise to diverse and specific biocoe- noses. Among submerged algae, a number of freshwater and brackish charophyte species were identified to represent five out of six genera within the family of Characeae [10]. Among the rarest brackish charophytes, Chara connivens P. Salzmann ex A. Braun 1835 exemplifies those species whose distribu- tion has been reported to have greatly declined [12,13]. Chara connivens is widely distributed, with records known from Europe, Africa and Northern Asia [6,12,14–16]. Within Europe, C. connivens was recorded in the western European maritime regions, along the coasts of the Mediterranean and the Baltic Sea, and in inland saline waters of central and southern Europe [4,6,12]. In Poland, historical records of the species are available for the Gulf of Gdańsk [4] and for the Vistula Lagoon [17]. Currently, C. connivens has a status of a strictly protected species. In the “Red list of plants and fungi in Poland”, published in 2006 [18], the species was assigned to the category Ex, i.e., extinct or probably extinct species. The present paper reports new records of C. connivens from the Vistula and the Szczecin Lagoons. The Vistula Lagoon observation is a rediscovery of C. connivens after almost 35 years of the previous record, while in the Szczecin Lagoon this species has never been noted so far. The occurrence of C. connivens was evidenced in the Pol- ish parts of the Vistula and Szczecin Lagoons (Fig. 1) during the vegetation studies performed on 6 July 2011 in the Vistula Lagoon and on 31 July and 14 August 2012 in the Szczecin Lagoon. The distribution and species composition of aquatic vegetation was determined by direct observations and from samples collected with an anchor. Additionally, in the Vistula Lagoon the floristic data collection was supplemented with measurements of water conductivity and temperature taken with a portable CTD probe. Chara connivens [syn. Chara globularis f. connivens (P. Salzmann ex A. Braun) R.D. Wood 1962] is a small alga, usually up to 15 cm long, rarely longer (25–50 cm) [4,12,13,15,19]. The slightly encrusted and slender thalli are delicate green and lustrous [4]. Sterile specimens of C. connivens are very similar to those of C. globularis Thuill. [15] due to presence of triplostichous stem cortex (usually isostichous or prime cells slightly larger than the secondaries) with lacking or rudimentary spine cells [4] and two rows of rudimentary stipulodes (uppers slightly larger than lowers or all imperceptible). The features important in distinguishing the two species include the branchlets (6–10 in a whorl composed of 6–13 segments each, out of which the terminal 1–2 celled segment is ecorticate) which in C. connivens are strongly incurved in fertile male specimens, often also in fertile female individuals [4,6,12,15]. This feature is marked on the photographs of individuals from the Szczecin (Fig. 2) and Vistula (Fig. 3) Lagoons. Additionally, the axial internodes are very long, up to 6 times as long as the branchlets [12]; this was observed in our collections (Fig. 3). The most important distinguishing trait is that C. connivens is dioecious, while C. globularis is monoecious. In C. connivens , antheridia and oogonia develop at the lowermost 1–4 and 1–3 branchlet nodes, respectively [4]. The red solitary antheridia of up to 1 mm in diameter in C. connivens are larger than those in C. globularis [12,16]. The oogonia are up to 1.1 mm long and the oospores are dark. The specimens collected in the two lagoons showed the characters described above, typical of the vegetative thallus parts of C. connivens . In addition, besides sterile specimens, both lagoons yielded fertile male specimens which were more abundant in the Szczecin Lagoon (Fig. 2), where fertile female individuals were found as well. On 6 July 2011, C. connivens was found in the western part of the Vistula Lagoon (Fig. 1), on sandy mud at a depth of 1.1 m. The area was partially isolated by abundant mono- specific assemblages of emergent vegetation, particularly Phragmites australis (Cav.) Steud. and Schoenoplectus lacustris (L.) Palla. As the site is shallow and the water dynamics is low, the water column temperature was high (19.5°C). The site is located 2 km away from the nearest river mouth; the riverine inflow resulted in low salinity (0.8 psu). The water was transparent down to the bottom; however, it was not possible to examine the submerged vegetation distribution from the shipboard as the bottom was densely covered by the filamentous green algae Cladophora sp., Oedogonium sp. and Rhizoclonium riparium (Roth) Harvey (those accounted for 90% of the biological material collected). The site sup- ported a high diversity of macrophyte species occurring as single and small-sized specimens. They were dominated ...
Context 2
... are a group of macroscopic green algae represented by 314 species [1] assigned to the family Chara- ceae within the phylum Chlorophyta; alternatively, they are treated as a separate phylum, the Charophyta [2]. The occurrence of most of the Characeae species in Europe is limited to clear, freshwater lakes of low fertility [3–8]. In response to increasing trophic status and the associated light limitation, many charophytes have therefore become rare, and are treated as sensitive bioindicators of water quality [6,9]. Although the number of sites with abundant charophyte vegetation has decreased, these macroalgae are widely distributed in different types of aquatic environments throughout the world. Due to their ability for ion regula- tion and osmotic adjustment, a set of charophyte species, commonly known from freshwaters, can occur in brackish coastal lagoons, as shown for the Baltic Sea [10]. In brackish waters, charophytes experience changes in osmotic pressure and mineral composition [7]. A brackish environment unique on a global scale is the Baltic Sea, the world’s largest brackish water body [11]. The variety of the Baltic coast types gives rise to diverse and specific biocoe- noses. Among submerged algae, a number of freshwater and brackish charophyte species were identified to represent five out of six genera within the family of Characeae [10]. Among the rarest brackish charophytes, Chara connivens P. Salzmann ex A. Braun 1835 exemplifies those species whose distribu- tion has been reported to have greatly declined [12,13]. Chara connivens is widely distributed, with records known from Europe, Africa and Northern Asia [6,12,14–16]. Within Europe, C. connivens was recorded in the western European maritime regions, along the coasts of the Mediterranean and the Baltic Sea, and in inland saline waters of central and southern Europe [4,6,12]. In Poland, historical records of the species are available for the Gulf of Gdańsk [4] and for the Vistula Lagoon [17]. Currently, C. connivens has a status of a strictly protected species. In the “Red list of plants and fungi in Poland”, published in 2006 [18], the species was assigned to the category Ex, i.e., extinct or probably extinct species. The present paper reports new records of C. connivens from the Vistula and the Szczecin Lagoons. The Vistula Lagoon observation is a rediscovery of C. connivens after almost 35 years of the previous record, while in the Szczecin Lagoon this species has never been noted so far. The occurrence of C. connivens was evidenced in the Pol- ish parts of the Vistula and Szczecin Lagoons (Fig. 1) during the vegetation studies performed on 6 July 2011 in the Vistula Lagoon and on 31 July and 14 August 2012 in the Szczecin Lagoon. The distribution and species composition of aquatic vegetation was determined by direct observations and from samples collected with an anchor. Additionally, in the Vistula Lagoon the floristic data collection was supplemented with measurements of water conductivity and temperature taken with a portable CTD probe. Chara connivens [syn. Chara globularis f. connivens (P. Salzmann ex A. Braun) R.D. Wood 1962] is a small alga, usually up to 15 cm long, rarely longer (25–50 cm) [4,12,13,15,19]. The slightly encrusted and slender thalli are delicate green and lustrous [4]. Sterile specimens of C. connivens are very similar to those of C. globularis Thuill. [15] due to presence of triplostichous stem cortex (usually isostichous or prime cells slightly larger than the secondaries) with lacking or rudimentary spine cells [4] and two rows of rudimentary stipulodes (uppers slightly larger than lowers or all imperceptible). The features important in distinguishing the two species include the branchlets (6–10 in a whorl composed of 6–13 segments each, out of which the terminal 1–2 celled segment is ecorticate) which in C. connivens are strongly incurved in fertile male specimens, often also in fertile female individuals [4,6,12,15]. This feature is marked on the photographs of individuals from the Szczecin (Fig. 2) and Vistula (Fig. 3) Lagoons. Additionally, the axial internodes are very long, up to 6 times as long as the branchlets [12]; this was observed in our collections (Fig. 3). The most important distinguishing trait is that C. connivens is dioecious, while C. globularis is monoecious. In C. connivens , antheridia and oogonia develop at the lowermost 1–4 and 1–3 branchlet nodes, respectively [4]. The red solitary antheridia of up to 1 mm in diameter in C. connivens are larger than those in C. globularis [12,16]. The oogonia are up to 1.1 mm long and the oospores are dark. The specimens collected in the two lagoons showed the characters described above, typical of the vegetative thallus parts of C. connivens . In addition, besides sterile specimens, both lagoons yielded fertile male specimens which were more abundant in the Szczecin Lagoon (Fig. 2), where fertile female individuals were found as well. On 6 July 2011, C. connivens was found in the western part of the Vistula Lagoon (Fig. 1), on sandy mud at a depth of 1.1 m. The area was partially isolated by abundant mono- specific assemblages of emergent vegetation, particularly Phragmites australis (Cav.) Steud. and Schoenoplectus lacustris (L.) Palla. As the site is shallow and the water dynamics is low, the water column temperature was high (19.5°C). The site is located 2 km away from the nearest river mouth; the riverine inflow resulted in low salinity (0.8 psu). The water was transparent down to the bottom; however, it was not possible to examine the submerged vegetation distribution from the shipboard as the bottom was densely covered by the filamentous green algae Cladophora sp., Oedogonium sp. and Rhizoclonium riparium (Roth) Harvey (those accounted for 90% of the biological material collected). The site sup- ported a high diversity of macrophyte species occurring as single and small-sized specimens. They were dominated ...
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Citations
... Recent field data of the Wielki Zalew already indicated Potamogeton perfoliatus and Myriophyllum spicatum at a depth of 2-2.2 m (Wozniczka, pers. com.) and the re-occurance of charophytes is reported by Brzeska et al. (2015). Charophytes were recently observed in the Kleines Haff, as well. ...
We combine historical and recent monitoring data with modeling to get a better insight into water quality development of the large Oder/Szczecin Lagoon at the German/Polish border in the southern Baltic Sea region and especially of the role of macrophytes. Data indicates that the system is eutrophic for centuries and a naturally eutrophic system. During the last decades, external nutrient loads decreased but still keep the system in a eutrophic state. The systems primary production is limited by light and nitrogen and cannot be sufficiently managed by external nutrient load reductions. We consider 36% macrophyte coverage of the lagoon area as potential historical maximum. Despite its shallowness the lagoon was never a macrophyte dominated, clear water system. About 31% of the lagoon area would be covered by macrophytes in a good ecological status according to the European Water Framework Directive. However, the existing water transparency targets seem too ambitious and not realistic. Changes in macrophyte coverage on water quality are restricted to near shore areas and hardly affect the open lagoon. Existing models require an improved representation of water transparency and effects on macrophyte colonization depth. Presently the patchy macrophyte coverage is only about 12% of the lagoon area. This low coverage and a relatively poor species composition results in a non-satisfactory state classification. However, ecologically valuable angiosperms and charophytes seem to recover. A strict avoidance of mechanical disturbances could be a measure to support macrophyte re-colonization. A systematic improvement of piscivorous fish stocks may be a supporting measure to reduce eutrophication. Restoration perspectives and consequences for environmental policies are discussed.
... Out of the three above mentioned estuarine regions from which C. connivens was recorded by the end of 19th, two still support populations of this species: the Vistula and the Oder estuaries, both with major lagoons there constituting refugia for the charophytes identified in more recent times (Brzeska et al., 2015;Garbacik-Wesołowska, 1969;Pliński et al., 1978;Szarejko, 1955;Urbaniak & Gąbka, 2014;Volodina & Gerb, 2018, this study). ...
... This situation implies the need to verify the status of C. connivens also on the HELCOM level, which has been already indicated by Rychter et al. (2018). These authors also drew attention to the 'rediscovery' of the species in the Vistula Lagoon by Brzeska et al. (2015), having noted the legal protection of this species in Poland. Blindow et al. (2003) suggested that legal protection of charophyte species is of minor importance as they are not threatened by collection activities. ...
... The rediscovered and newly discovered populations of C. connivens in the Vistula and Szczecin Lagoons presented in this article confirm the predictions of Torn et al. (2020), at least in case of Lake Wicko Wielkie (northernmost part of the Szczecin Lagoon). Previously, no charophytes were recorded from this area (Garbacik-Wesołowska, 1969), but in 2012 this species turned out to be abundant locally, forming a dense assemblage without any other chrophytes (Brzeska et al., 2015). Along in the Vistula Spit, the species was found to be still frequent, but in scarcity or rarely in small and not dense patches, co-occurring with C. aspera, C. contraria, C. globularis, C. tomentosa and N. obtusa (Krajewski et al., 2015;Brzeska-Roszczyk, 2020;this study). ...
The occurrence of Chara connivens (Charophyta, Characeae) and its status in the Baltic Sea may raise controversies regarding its origin and historical dispersal pathways in the area. This study critically revises the protection status of C. connivens in the countries around the Baltic Sea, as well as its status on the red lists of endangered plant species (including the HELCOM Red List). The first reports on the presence of C. connivens in the Baltic Sea area were published in the aftermath of Carl Baenitz’s talks given in the early 1870s. Already then, the scientific community was well aware of the fact that C. connivens had been introduced as a ballast plant to the known Baltic areas of occurrence – the first known record of the species is of 1829. Since Poland is the only country where C. connivens is protected, the historical and contemporary distribution of this charophyte in the Polish coastal waters is presented against the background of the available historical and recent records of the species in the Baltic Sea. Recent reports from the second half of the 20th century and the beginning of the 21st century have confirmed a fairly common occurrence of C. connivens in Estonia, Sweden and Poland. This species still occurs on the German coast and has also been reported from Finland (the Åland archipelago). In recent
decades, however, the species was considered rare in the Baltic Sea area. In Poland, C. connivens was even classified as extinct, despite earlier data on its occurrence in the Vistula Lagoon in the 1970s, where it was rediscovered in 2011. It was also found in the Szczecin Lagoon a year later. Both localities well suit Luther’s pattern of C. connivens occurrence in areas with intensive shipping and ballast discharge operations in historical times. Based on this in-depth revision of historical and current distribution, it is postulated that C. connivens, as non-indigenous, should not be red-listed in the Baltic Sea area, following the example of Finland. Moreover, its legal status in Poland of a strictly protected species should be reconsidered.
... Modeltest3.7 [34] was used to determine the parameters and the best surrogate model for each marker (Table 3). Diagnosis: This species is similar to Chara connivens, but the cortex of the latter is triplotichous and obviously different from this species [35][36][37][38]. It is also related to Chara virgata (=C. ...
... In addition, the based nodes of branchlets of the new species sometimes were ecorticate, and multiple structures were also shorter or smaller than those of C. connivens. According to some references [35][36][37][38], C. connivens habitats in mesotrophic to eutrophic freshwater or brackish water, but the new species was found only in one type of locality, oligotrophic freshwater. ...
... This also means that the importance of the arrangement of the cortex and monoecious/dioecious in taxonomy need further discussion. In addition, C. virgata habitats in oligotrophic freshwater or occasionally brackish water and differs from the new species [35,39,40]. ...
A new species of freshwater alga, Chara zhengzhouensis, is described and illustrated based on material collected in a lake at Zhengzhou, in Henan Province, China. Phylogenetic analysis of sequence data from the 18s rDNA, rbcL, and atpB indicated the separation between C. zhengzhouensis and other species of the genus Chara. Additionally, from a morphological point of view, C. zhengzhouensis differs from another closely related species, C. connivens, in its diplostichous cortex and corticate or ecorticate in based segments of branchlets. Therefore, the results based on both morphological observation and molecular evidence facilitated the proposal of this new species—C. zhengzhouensis. It represents another species in the charophyte diversity in China and the description of this new species provides more molecular data for phylogenetic analysis of the genus Chara.
... Recent eld data of the Wielki Zalew already indicated Potamogeton perfoliatus and Myriophyllum spicatum at a depth of 2-2.2 m (Wozniczka, pers. com.) and the re-occurance of charophytes is reported by Brzeska et al. (2015). Charophytes were recently observed in the Kleines Haff, as well. ...
We combine historical and recent monitoring data with modeling to get a better insight into water quality development of the large Oder/Szczecin Lagoon and especially the role of macrophytes. Data indicates that the system is eutrophic for centuries and a naturally eutrophic system. During the last decades, external nutrient loads decreased but keep the system in a eutrophic state. The systems primary production is limited by light and nitrogen and cannot be sufficiently managed by external nutrient load reductions. We consider 36% macrophyte coverage of the lagoon area as potential historical maximum. Despite its shallowness the lagoon was never a macrophyte dominated, clear water system. About 31% of the lagoon area would be covered by macrophytes in a good ecological status according to the Water Framework Directive. However, the existing water transparency targets seem too ambitious and not realistic. Changes in macrophyte coverage on water quality are restricted to near shore areas and hardly affect the open lagoon. Existing models require an improved representation of water transparency and effects on macrophyte colonization depth. Presently the patchy macrophyte coverage is only about 12% of the lagoon area. This low coverage and a relatively poor species composition results in a non-satisfactory state classification. However, ecologically valuable angiosperms and charophytes seem to recover. A strict avoidance of mechanical disturbances could be a measure to support macrophyte re-colonization. A systematic improvement of piscivorous fish stocks may be a supporting measure to reduce eutrophication.
... In the Baltic Sea, the studies on oospore bank have been conducted only along the German coastline [3][4][5], where in contrast to the recent vegetation (angiosperm dominated), more oospores than seeds of angiosperms have been found in the sediment samples. Extensive studies on the distribution of charophytes have been performed in Swedish, Polish, and Estonian coastal waters [6][7][8][9], but obtained results have not been related to an oospore bank. ...
Lack of knowledge about distribution of charophyte fructifications and importance of environmental conditions in the Baltic Sea coastal waters fostered us to assess the spatial-temporal patterns of oospore bank in relationship with environmental factors in the Curonian Lagoon (Lithuanian part). We mapped the distribution of oospores in 2017–2019. The importance of environmental factors was determined by the cluster analysis and boosted regression trees. Four oospores species were recorded up to 4 m depth. The highest mean densities (58,000 ind·m⁻²) of viable fructifications were found along the eastern shore, where the densest charophyte stands were recorded. Viable fructifications showed a clear pattern of filling the oospore bank after the vegetation season and a depletion during the summer as they germinated. The distance from charophyte stands, salinity, bottom slope aspect, and wave exposure were the most important environmental variables. Full fructifications mostly occurred within <0.5 km distance from the charophyte stands restricted to flat and sheltered areas exposed to the northern and eastern slopes. Empty fructifications were mostly found within <2 km distance from the charophyte stands but their high density was limited to <1 km distance from the charophyte stands and on the northeastern bottom slopes and >1.5 salinity.
... Although the species is believed to be introduced to Baltic Sea from western Europa by ballast water of ships [20], the proven origin of the species is remained unclear and species is categorised as cryptic [18]. Chara connivens has been recorded in single locations in the 1960s in the Estonian coastal sea, following the continuous enlargement of distribution area since 2005 [18], [21]. The alien species G. tigrinus occurs naturally in North America. ...
... Among the recent benthic invaders, G. tigrinus have proven to be the most aggressive in the Baltic Sea [39]. Already two years after the first finding, the species accounted for about 50% of the total occurrence of gammarids in the south coast of Saaremaa Island [21]. G. tigrinus is more selective about environmental conditions in Estonian waters compared to its native range. ...
The ongoing climate change is expected to affect the distribution and vitality of marine aquatic species through various links and changes in environmental conditions. The aim of the study was to analyse and compare climate change related effects on native and non-native benthic species groups in the Baltic Sea. We analysed the impact of changes on the charophytes (native Chara aspera and non-native Chara connivens) and gammarid amphipods (native Gammarus salinus and non-native Gammarus tigrinus). Currently, C. aspera and G. salinus are the most widespread and frequent species among charophytes and gammarids in NE Baltic Sea. C. connivens has been recorded in single locations in the 1960s, following the continuous enlargement of the distribution area since 2005. G. tigrinus has showed significant occupation success in the region since their first finding in 2003. The random forest modelling method was used to produce current species distribution models and to predict the potential changes of distribution based on future climate scenarios. In the brackish Baltic Sea, species are often living close to their salinity tolerance limits and the decrease in salinity will probably cause profound changes in distribution of both marine and freshwater species. Moreover, the model predictions showed that, probably due to wider salinity and temperature tolerance, the non-native species will gain advantages over native species. Due to climate change, a significant increase of the distribution areas of non-native species is expected to occur on account of the native species. The distribution area of C. connivens is predicted to double and G. tigrinus to increase by 15%. Changes in environmental conditions also favour the distribution of native charophyte C. aspera due to the freshwater origin of the species. However, the marine species G. salinus is predicted to lose 65% of its distribution area.
... ex Steud. and Scripus lacustris L., rarely Typha angustifolia L., which on the open water side border on a belt of elodeids dominated by species of the Potamogeton L. genus, accompanied by Myriophyllum spicatum L. Shallow muddy bays are found along the western coast of the lagoon, usually densely covered by Potamogeton spp., Ceratophyllum spp., Zannichellia palustris L., Chara species and nymphaeids Nuphar lutea L., Nymphaea alba L., Hydrocharis morsus-ranae L. The submerged vegetation is often covered with thick "algal mats" of filamentous green algae Cladophora sp., Oedogonium sp. and Rhizoclonium riparium (Roth) Harvey (Pliński et al 1978;Brzeska et al. 2015). Since the 1970s, there has been a significant reduction in the area covered by elodeids and nymphaeids, presumably due to increasing trophic status (Pliński et al 1978;Pliński 1995). ...
The paper presents the first data on the concentrations of heavy metals (Cd, Pb, Zn, Cu, Ni, Cr, Mn) and ¹³⁷ Cs and their contamination ratios (CR) in the most abundant species of macrophytes in the Vistula Lagoon. No significant differences in the concentrations of heavy metals and ¹³⁷ Cs between macrophyte taxa or the influence of rivers flowing into the Vistula Lagoon on heavy metal concentrations in the area were found. The concentrations of heavy metals in macrophyte taxa varied in the following ranges: Cd – 0.1–0.7 mg kg ⁻¹ d.w.; Pb – 0.5–5.0 mg kg ⁻¹ d.w.; Zn – 29–390 mg kg ⁻¹ d.w.; Cu – 2.5–8.3 mg kg ⁻¹ d.w.; Ni – 0.4–6.8 mg kg ⁻¹ d.w.; Cr – 0.5–2.8 mg kg ⁻¹ d.w.; Mn – 380–8500 mg kg ⁻¹ d.w. Since the 1990s, a decline or stable state of heavy metal concentrations in bottom sediments has been observed, reflecting changes in the environment of the Vistula Lagoon. The linear sedimentation rate in the Vistula Lagoon was 3.3 mm y ⁻¹ . The results presented in the paper can serve as a baseline for assessing changes in the environmental status of the Vistula Lagoon, which may occur as a result of future investments, including building a new navigable canal through the Vistula Spit.
... They are widely distributed in freshwater as well as brackish and marine habitats, from tropical to polar regions (Wood 1965). The occurrence of Characeae taxa is mostly limited to clear, freshwater lakes with low fertility (Dąmbska 1964;Krause 1969;1981;1997;Martin et al. 2003;Brzeska et al. 2015). Many stonewort species are characteristic of hard, oligo-mesotrophic water ecosystems (Krause 1981;1997). ...
... Chara connivens P. Salzmann ex A. Braun, known as a convergent stonewort, belongs to the group of brackish charophytes. To date, C. connivens has been reported mainly from Western Europe, the Mediterranean Sea basin region and the Baltic Sea (Krause 1981;1997;Torn et al. 2004;Urbaniak & Gąbka 2014;Brzeska et al. 2015). Several stands of C. connivens were also located in the inland saline waters of Central and Southern Europe (Dąmbska 1964;Krause 1997;. ...
... Communities with C. connivens are mostly pioneer in ephemeral shallow waterbodies (Felzines & Lambert 2012). In Europe, C. connivens stands were recorded in Albania (Zeneli & Kashta 2016), Bulgaria (Temniskova et al. 2008), Estonia Kotta et al. 2004;Torn et al. 2015), Finland (Appelgren et al. 2004), France (Hy 1913;Corillion 1957), Georgia (Barinova & Kukhaleishvili 2014), Germany (Wood 1965;Luther 1979;Ludwig & Schnittler 1996), Great Britain (Stewart & Church 1992;Bryant & Stewart 2002;John et al. 2011), Greece (Langangen 2010;, Ireland (Stewart & Church 1992), Latvia (Skuja 1928;Kostkevičienė & Sinkevičiene 2008), the Netherlands Bruinsma 2000;Bruinsma et al. 2018), Poland (Urbaniak & Blaženčić 2012;Urbaniak & Gąbka 2014;Brzeska et al. 2015;Krajewski et al. 2015), Portugal (Corillion 1957;Cambra Sánchez et al. 1998), Romania (Caraus 2002;2017), Russia (Kaliningrad Oblast) (Romanov et al. 2018a,b), Spain (Reyes Prósper 1910;Aboal 1985;Cambra Sánchez et al. 1998;Cirujano et al. 2008;del Pozo et al. 2011), and Sweden (Luther 1979;Blindow 1988;Wallström & Persson 1999;Tolstoy & Österlund 2003;Torn et al. 2004;Langangen 2007). In Africa, populations of C. connivens were found in Algeria (Wood 1965;Muller et al. 2017), Egypt (Corillion 1957), Morocco (Wood 1965;Muller et al. 2017), and Tunisia (Corillion 1957;Wood 1965;Muller et al. 2017). ...
The paper presents the first record of a Chara connivens (Characeae) stand from Fuerteventura (Canary Islands, Spain). The species was previously recorded only on Tenerife and Lanzarote, mostly in marine and artificial habitats. Physicochemical parameters of water and morphological features of the thalli and plant community were analyzed. General habitat requirements of C. connivens populations located in Europe, North Africa, and South-West Asia were reviewed. The newly described stand was located in a natural rock crevice that was part of a riverbed in El Barranco de las Peñitas (Penitas Canyon). This habitat was unshaded and filled with brackish water. C. connivens co-occurred with Cladophora glomerata and Ruppia maritima . Our report on the presence of C. connivens in the Spanish territory of the Atlantic Ocean is the first in almost 40 years. The distribution of C. connivens and its plant associations on the Canary Archipelago are poorly explored, which is why this topic requires further research.
... Our field surveys and a literature study proves that different submerse macrophyte species are still present in the western lagoon and single macrophyte stands were found in a water depth of up to 1.8 m. This is true for the eastern, Polish part as well (Brzeska et al. 2015). Recent studies by Nowak et al. (2008) and Blindow et al. (2016) documented that germinable diaspores of several species are present in the sediments of all observed German Baltic coastal water. ...
The Systems Approach Framework with an integrated Ecological-Social-Economic assessment was applied to address the issue of zebra mussel (Dreissena polymorpha) farming in the large Oder (Szczecin) Lagoon, southern Baltic Sea. Heavy eutrophication hampers the use of the lagoon and zebra mussel farming is considered as new use and potential measure to improve water quality. Three alternative scenarios were developed in interaction with local stakeholders: 1) the production of mussels as fresh feed and meal on a commercial basis seemed not profitable, because of a limited market for fresh mussels (zoos, aquaculture) and low prices for organic feed. 2) Mussel cultivation to improve transparency and attractiveness of bathing waters near beaches had only a limited potential (0.2 m improvement of Secchi depth). A higher mussel biomass would increase the risk of temporary hypoxia. 3) Mussels farms for improving the environmental status (according to EU Water Framework Directive) by supporting macrophyte restoration were considered as the most promising scenario. Our model simulations suggested that as soon as a compensation for nutrient removal is considered, all mussel farm scenarios could cover the costs. Experiments and literature confirm that the conditions for an environmental friendly farming approach in the lagoon are suitable. Steps towards and problems associated with an implementation, e.g. invasion of Dreissena bugensis (quagga mussel), are discussed. Each step of the Ecological-Social-Economic assessment and major lessons learnt are documented in detail. Altogether, the approach turned out to be very suitable for this issue.
... Despite the narrowest breadth of environmental niche space compared to other studied species , Chara connivens will benefit the most from climate change. During the last 20 years the distribution of C. connivens has been increasing in the Estonian coastal waters (Torn et al. 2004(Torn et al. , 2015 as well as in the Baltic Sea (Appelgren et al. 2004;HELCOM 2013b;Brzeska et al. 2015). The predicted occurrence of the marine species Zostera marina decreased under lower salinity conditions. ...
The potential response of occurrence of charophyte and angiosperm communities to climate change in the brackish environment of the Baltic Sea was investigated using the boosted regression trees (BRT) modelling method. The aim of the study was to analyse sensitivity of various species to climate change and to predict the changes in species’ distribution under projected changes of environmental variables. The results showed that depth was the most influential environmental variable in predicting the spatial distribution of charophytes and angiosperms. Other environmental variables had notably lower importance in determining community structure and the order of importance was species specific. The exceptions were the charophytes Chara horrida and C. tomentosa, for which the influence of wave exposure was stronger than the influence of depth. The studied species could be divided into three groups based on the predicted effect of climate change: (1) species that benefit from change (Chara connivens, Potamogeton perfoliatus, Myriophyllum spicatum, C. aspera, C. baltica, C. canescens, Ruppia maritima), (2) species with no notable change (Chara tomentosa, C. horrida, Stuckenia pectinata), and (3) species that decline (Zostera marina, Zannichellia palustris, Tolypella nidifica). Currently, the shallow and sheltered West Estonian Archipelago Sea hosts favourable habitat conditions for most of the charophyte and angiosperm species. The most significant predicted change was the decline or disappearance of brackish and marine species and the increase of freshwater species due to the expected decrease of salinity in the Baltic Sea.
