Marenzelleria cf. viridis (Polychaeta: Spionidae) – ecophysiological adaptations to a life in the coastal waters of the Baltic Sea

Since its introduction into the Baltic Sea about ten years ago, the polychaete species Marenzelleria cf. viridis has spread rapidly. Meanwhile, this spionid settled in remarkable numbers predominantly in the coastal waters which provide some of the more variable and unstable habitats in terms of abiotic conditions. In the present paper, some of the underlying biochemical and physiological processes were experimentally examined which enables this polychaete to deal with several kinds of environmental stress such as variations in salinities, low oxygen concentrations and occurrence of hydrogen sulphide. The results obtained reveal that in the process of acclimation to different salinities free amino acids are involved, mainly alanine and glycine. The content of these amino acids were increased in worms acclimated to a higher salinity. When exposed to low ambient oxygen concentrations (severe hypoxia) M. cf. viridis started to produce energy anaerobically via pathways known from several other marine organisms. The presence of hydrogen sulphide in higher concentrations (1 mmol l^-1) results in a more rapid production of succinate (indicator for anaerobic energy production via the succinate-propionate pathway) as compared to hypoxia alone, indicating a higher energy demand. Nevertheless, when exposed to enhanced ambient hydrogen sulphide concentrations (3 mmol l^-1), M. cf. viridis is less affected by this toxic compound than other marine species, such as the related species Marenzelleria cf. wireni (North Sea). The field data indicate that the metabolic response obtained under experimental conditions is also important in the worm's natural habitat. Although the extent of anaerobic metabolites produced as well as the amount of thiosulphate (main sulphide detoxification product) was lower in the field as compared to the experiments, M. cf. viridis very likely has to face hypoxia and hydrogen sulphide in higher concentrations in its natural habitat.     

Factors controlling the distribution of Marenzelleria cf. viridis, Pygospio elegans and Streblospio shrubsoli (Polychaeta: Spionidae) in the southern Baltic Sea, with special attention for the response to an event of hypoxia

The large-scale distribution patterns of the estuarine spionid polychaetes Marenzelleria cf. viridis, Pygospio elegans, and Streblospio shrubsoli were studied in the Pomeranian Bay (southern Baltic Sea) at 20 stations in April 1993 and their relationship with hydrographic factors and sediment composition investigated. The densities of M. cf. viridis and S. shrubsoli decreased rapidly with increasing distance offshore. A corresponding decrease in phytoplankton concentration offshore is suggested as the main cause for the observed spatial patterns. P. elegans was more evenly distributed. At 10 selected stations further samples were collected between April 1993 and July 1996 to study the response of abundance and biomass of the three polychaetes to changes in environmental conditions and to investigate interspecific interactions within the macrofauna. Salinity, pelagic food supply, and sediment parameters did not change. At three of these stations redox potential of the sediment and macrofauna composition were affected by an unusual hypoxic/anoxic event in July/August 1994. All three spionid species were able to survive moderate seasonal hypoxic conditions, but died after exposure to severe anoxia. Special attention was focused on the re-establishment of the spionids. The rate with which M. cf. viridis and P. elegans re-colonised defaunated stations varied between a few weeks and two years. These differences in rate of re-establishment were attributed to the distance from undisturbed recruitment areas, and to the severity of the oxygen deficiency. Increasing densities of P. elegans and S. shrubsoli after the hypoxic event coincided with a reduced abundance of the bivalve Mya arenaria, suggesting a negative interspecific interaction.     

Marenzelleria cf. viridis and the sulphide regime

To find out how the polychaete Marenzelleria cf. viridis could spread successfully into the habitat of the Darss-Zingst Bodden Chain, one important environmental factor for sediment dwelling animals was examined: hydrogen sulphide. To investigate the stress of this environmental factor, hydrogen sulphide was continuously examined in the pore water of the sediment and burrows of M. cf. viridis. Metabolic activity was recorded by direct and indirect calorimetry. Depending on water temperature, organic matter content of the sediment and salinity, the sulphide concentration in the pore water varied between 1.5 and 4.2 mmol l^-1 being high during summer and in winter when the sediment and overlying water was ice covered. In microcosm experiments water of M. cf. viridis-burrows showed variations in sulphide between 145 and 210 µmol l^-1 but pore water concentration was much higher (6.5 mmol l^-1). In the presence of oxygen animals exhibited an accelerated metabolic rate which was met by a fully aerobic metabolism at Po₂ of 20 to 7.5 kPa and sulphide concentration of 215–245 µmol l^-1. When oxygen is absent the heat production was only slightly elevated (103%) when compared to the anoxic control. The elevated heat production of the animals during sulphide exposure and oxygen may be due to detoxification processes. In this case thiosulphate is formed probably via mitochondrial oxidation and therefore may account for additional ATP-gain.     

Marenzelleria cf. wireni (Polychaeta: Spionidae) from the Tay estuary. Metabolic response to severe hypoxia and hydrogen sulphide

The appearance of the spionid polychaete Marenzelleria spp. in the Tay estuary (Scotland) was first reported in 1984. Since estuaries are known as environments where abiotic conditions fluctuate widely, a laboratory study was conducted aimed to elucidate how this introduced species deals with low oxygen concentrations and exposure to hydrogen sulphide. Experimental evidence reveals that during severe hypoxia Marenzelleria cf. wireni switched to anaerobic pathways known from other marine invertebrates. Under the influence of sulphide (1 mmol l^-1) accumulation of anaerobic end products is more pronounced. It is assumed that in the presence of sulphide, due to its inhibition of aerobic respiration, the worms have to switch to anaerobic energy production directly after the onset of hypoxia. Seasonal differences in the metabolic reaction were found. It was shown that in specimens that were filled with gametes (winter), accumulation of end products of anaerobic metabolism was more pronounced than in immature worms (summer). The amount of succinate, an indicator for anaerobic energy production for instance, was nearly twice as high in the winter specimens. Since the amount of thiosulphate (a typical sulphide detoxification product) in the tissues is relatively low, it is suggested that Marenzelleria cf. wireni also accumulates other detoxification products. Sulphite, however, also known as a detoxification product, was found only in traces. Field measurements provide evidence that the potential of Marenzelleria cf. wireni to survive low oxygen and high sulphide concentrations is clearly higher than that normally needed in the Tay estuary.     

Population dynamics, growth and production of the neozoon Marenzelleria cf. viridis (Verrill, 1873) (Polychaeta: Spionidae) in a coastal water of the southern Baltic Sea

The propagation of an immigrant from North America, viz. the spionid Marenzelleria cf. viridis in the Darss-Zingst Bodden (DZB) (southern Baltic Sea), was studied at three stations from March 1992 to December 1995. Highest mean abundances (over 28 000 ind. m^-2) and wet weights (400 g m^-2) were recorded at station 2 in 1994. The spionid also reached its highest dominances in terms of biomass (40 to 90%) at this station, which was selected for the population dynamics, growth and secondary production studies. The spionid has a life span of about 3 years, and many individuals achieved sexual maturity after one year. Their growth curve is steepest during the first year of life, during which the animals grow to a length of about 180 segments. However, growth depression was observed during the ripening of the gametes in April, May and June. Secondary production was in the region of 55 to 85 g AFDW m^-2 y^-1. Productivity (P/B) varied considerably from generation to generation, ranging between 0 and 4.8 with an average between 1.2 and 1.6.     

Marenzelleria viridis (Polychaeta: Spionidae): a review of its reproduction

The features of the reproductive biology such as morphology of gametes, larval morphology, larval development and development of gametes of Marenzelleria viridis Type II from the Baltic were summarized. Further reproductive features of Baltic Sea populations are given and the purpose of the review is to account for the successful immigration of M. viridis into the oligohaline areas of the Baltic considered against a background of such variables as population density and structure, salinity, temperature, food availability, oxygen and sulphide levels. Gametogenesis started in spring. Fecundity of animals depended on salinity, temperature, age and size of worms. Mature oocytes contained large cortical alveoli not yet known for polychaetes. Animals spawned in autumn in all years of investigation. The pelagic larvae of M. viridis Type II were found mainly from September to November. Larval development depended on water temperature and lasted about 4 to 12 weeks. Successful larval development from egg to juvenile was not possible below salinities of 5, but colonization of oligohaline regions took place by larvae with more than 4 setigers or by swimming juveniles. Reproductive features of M. viridis Type II from the Baltic were compared and discussed with the results of M. viridis Type I populations from the North Sea and North America. The two M. viridis types reproduced at different time, M. viridis Type I reproduced in spring and M. viridis Type II in autumn. Both types showed also differences in larval development, gametal development and sex ratio of mature worms.     

A new Spionidae (Polychaeta) from North Carolina, and a redescription of Marenzelleria wireni Augener, 1913, from Spitsbergen, with a key for all species of Marenzelleria

Marenzelleria bastropi, a new species of Spionidae (Polychaeta) from the brackish water Currituck Sound, North Carolina, is described. The new species is characterized by the great number of chaetigers between the first neuro- and notopodial hooded hooks, the extension of the nuchal organ up to the end of chaetiger 2/middle of chaetiger 3 and the presence of about 60–90 branchiate chaetigers. Marenzelleria bastropi sp. nov. is closely related to M. neglecta (Sikorski and Bick, 2004) and Marenzelleria viridis (Verrill, 1873). Marenzelleria wireni Augener, 1913 is described here for the first time from western Spitsbergen. Adult specimens are investigated and compared with specimens from other areas of distribution. A key for subadult and adult specimens of all Marenzelleria species is provided.     

Temperature-induced changes in the locomotor capacity of juveniles of Marenzelleria viridis (Polychaeta, Spionidae)

Abstract. Populations of Marenzelleria viridis in the Chester River (Kent County, Maryland) experience temperatures ranging from over 30°C in summer to near freezing in winter. Interestingly, M. viridis swims actively in winter. This observation led us to examine the relationship between locomotor capacity and temperature in individuals of M. viridis . Juvenile specimens were collected in February ("cold animals") and June ("warm animals"). Video analysis revealed that swimming is achieved by flexing the body in cyclic, helical waves. Wave frequencies were measured as an index of locomotor capacity at 5°C, 15°C, and 25°C. The mean wave frequencies of cold animals were 5.4 Hz at 5°C and 7.1 Hz at 15°C (Q₁₀= 1.3); the mean wave frequencies of warm animals were 6.1 Hz at 15°C and 7.8 Hz at 25°C (Q₁₀= 1.3). The effects of changes in water viscosity on wave frequency between 5–25°C were not significant. These results demonstrate that the temperature sensitivity of locomotor capacity in juvenile M. viridis is quite low. We conclude that low temperature sensitivity enables M. viridis to be active throughout the year.     

Influence of salinity and temperature on growth and survival of the planktonic larvae of Marenzelleria viridis (Polychaeta, Spionidae)

In a series of experiments, the planktonic larvae of Marenzelleriaviridis (Verrill, 1873) were exposed to various combinationsof salinity (S = 0.6, 2.5, 5.0, 10 and 20) and temperature (T= 5, 10 and 20C) from the 1-setiger stage to the onset of metamorphosis(16- to 17-setiger stage). One-setiger larvae were unable tocomplete their development to metamorphosis at salinities below5. Metamorphosis was successful at salinities of 10 and 20,when the animals adopted a benthic life mode. Larval developmentwas more rapid at 10 than at 20, and was positively affectedby higher temperatures. Larvae exposed to a salinity of 3.5at the 4- to 5-setiger stage developed and completed metamorphosisto benthic juveniles despite the low salinity. These larvaedeveloped most rapidly at a temperature of 10C. The salinitytolerances (LC₅₀) of M. viridis larvae (t = 48 h), juvenilesand adults (t = 72 h in each case) were determined at 10C.The results showed that all development stages can toleratesalmities <1 The importance of constraints on developmentand tolerance to low salinities for the successful colonizationof oligohaline regions is shown and discussed in connectionwith other brackish-water organisms.     

Inhibition of larval recruitment of ARmandia sp. (Polychaeta: Opheliidae) by established adults of Pseudopolydora paucibranchiata (Okuda) (Polychaeta : Spionidae) on an intertidal sand flat

Inhibition of larval settlement by a dense assemblage of established adults was examined by observing natural and experimental abundance patterns of two polychaete species on an intertidal sand flat in west Kyushu, Japan. A cage left for 43 days in the field in spring-summer brought about a remarkable increase in the within-cage density of adults of the tube-building spionid polychaete Pseudopolydorapaucibranchiata (Okuda) as compared with the density in an uncaged plot (× 52). In contrast, the densities of juveniles of the burrowing opheliid polychaete Armandia sp. showed an inverse trend (× $\text{1}\text{22}$). The attractiveness of the within-cage sediment for settling larvae of Armandia (cage-induced artifact) was assessed in a laboratory experiment: given an alternative choice between the sediments from the cage and the uncaged plot, Armandia larvae produced by artificial fertilization showed no substratum-preference. In another laboratory experiment, it was confirmed that Pseudopolydora paucibranchiata adults at a density of only $\text{1}\text{30}$ of that in the cage exerted a great lethal effect (probably ingestion) on Armandia larvae. These two results strongly support the hypothesis that the low density of Armandia juveniles in the cage was induced not through avoidance of the cage sediment by the larvae themselves but through inhibition of recruitment by the dense assemblage of established Pseudopolydora paucibranchiata adults in the cage. Moreover, the natural abundance pattern of Armandia juveniles in summer could partly be explained in relation to spatial and temporal changes in the density of Pseudopolydora paucibranchiata adults.     

Palp morphology in two species of Prionospio (Polychaeta: Spionidae)

The palp morphology of Prionospio fallax Söderström, 1920 from Sweden and Prionospio cf. saldanha Day, 1961 from Thailand was examined with a scanning electron microscope. Prionospio fallax was also studied in vivo using light-microscopy. Both species have grooved feeding palps, adorned with up to five ciliary characters: frontal cilia, transverse ciliary bands (or bandlets), latero-frontal cirri, lateral cilia and randomly distributed non-motile cirri. All, except the frontal cilia and non-motile cirri, are asymmetrically arranged relative to the long axis of the palps. Prionospio fallax possesses transverse bandlets and the other four groups, while P. cf. saldanha has transverse bands (consisting of several contiguous bandlets), frontal cilia and some randomly scattered cirri. Asymmetrical palp ciliation was previously only known in Marenzelleria viridis (Verril, 1873) and the genus Scolelepis Blainville, 1828. The newly recognised transverse ciliary bands and bandlets are considered to be homologous with the transverse ciliary rows found basally on the palps of Paraprionospio pinnata (Ehlers, 1901). This multistate character (named transverse cilia) may prove useful in elucidating the phylogeny of the Prionospio-complex of genera.     

The analysis of small-and mesoscale dispersion patterns ofMarenzelleria viridis (Polychaeta: Spionidae) in a coastal water area of the southern Baltic

The horizontal mesoscale distribution ofMarenzelleria viridis (Verrill, 1873), a spionid polychaete introduced from North American coastal waters during the 1980s, was studied in shallow water in the southern Baltic (German coast). The polychaete achieved an individual dominance of 80% and abundances up to around 8500 ind./m². Samples taken from a small (1.2 m×1.2 m, 6×6 samples, depth 0–35 cm) and a large station grid (5.5 m×5.5 m, 11×11 samples, depth 0–35 cm) were used to calculate dispersion indices for subpopulations of adult and juvenileM. viridis and subdominant chironimids (theChironomus plumosus andCh. halophilus complexes). The distribution patterns were significantly patchy. The patch sizes were estimated with the help of the dispersion indices and by analysing the correlograms in which spatial autocorrelations such as Moran's I and Geary's c values were plotted versus the field distance k. The patch sizes were heterogenous. The smallest patches found were 0.04 m². The largest sizes observed were 9 m². It is conceivable that smaller patches merge to form larger aggregations. Calculation of the abundance and rank correlations between subpopulations revealed significant positive relationships. These indicate principal suspension feeding. Sediment structure, substrate preference, feeding mode and biotic or abiotic attraction centres are considered to be the main causes of aggregation and the positive correlations.     

Effects of temperature,salinity and their interaction on growth of the benthic dinoflagellate Ostreopsis cf. ovata (Dinophyceae) from Japanese coastal waters

Benthic dinoflagellates of the genus Ostreopsis produce palytoxin (PTX)‐like compounds. The worldwide distributed Ostreopsis ovata/O. cf. ovata is potentially responsible for outbreaks of human health problems around the coasts of tropical, subtropical, and temperate regions. The present study examined growth responses of an O. cf. ovata strain s0662 collected from coastal waters of Japan with 35 different combinations of temperature (15–35°C) and salinity (20–40) and discusses the bloom dynamics of the organism in Japanese coastal environments. The O. cf. ovata strain s0662 tolerated a wide range of temperature (17.5–35°C) and salinity (25–40). Results of a two‐way ANOVA showed significant effects of temperature‐salinity interaction on growth rates and biomass yields of the O. cf. ovata strain (F(24,70) > 127, P < 0.001). The strain showed a maximal growth rate (1.03 divisions day^?1) and biomass yield (240 relative fluorescence) at temperature 25°C and salinity 30. The high growth rates of over 1.0 division day^?1 were obtained in conditions of temperature 25–30°C and salinity 30–35, which indicates that strain s0662 prefers high temperature and salinity conditions. The growth rates of O. cf. ovata under the optimal conditions were higher than those of other benthic toxic‐dinoflagellates, Coolia monotis, Gambierdiscus toxicus, and Prorocentrum lima (Dinophyceae) previously reported. Taken together, we suggest that O. cf. ovata is able to grow faster than the other benthic dinoflagellates in waters of high temperature and salinity. The physiological feature probably confers an ecological advantage on O. cf. ovata in the bloom development during warmer seasons in Japan and may be responsible for outbreaks of PTX‐like poisoning in the region especially during the warmer seasons.     

Cyclocarya cf. paliurus （Batal.） Iljinskaja （Juglandaceae） from the Hunchun Formation （Eocene）, Jilin Province, China

The leaflet architecture of Cyclocarya cf. paliurus （Batal.） Iljinskaja from the Hunchun Formation （Middle Eocene） shows similarity to that of modem C. paliurus （Batal.） Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records, such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the Eocene period.     

Cyclocarya cf. paliurus (Batal.) Iljinskaja (Juglandaceae) from the Hunchun Formation (Eocene), Jilin Province, China

The leaflet architecture of Cyclocarya cf. paliurus (Batal.) Iljinskaja from the Hunchun Formation (Middle Eocene) shows similarity to that of modern C. paliurus (Batal.) Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records,such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the Eocene period.     

The morphology and ecology of Dipolydora armata (Polychaeta, Spionidae) from the western Mediterranean Sea

Bick. A. 2001. The morphology and ecology of Dipolydora armata (Polychaeta, Spionidae) from the western Mediterranean Sea. — Acta Zoologica (Stockholm) 82 : 177–187
The cosmopolitan spionid Dipolydora armata is a dominant species of epifauna on Thais haemastoma shells in the western Mediterranean Sea. Some characters, particularly number, thickness and arrangement of notopodial spines, were extremely variable among specimens. Three morphological forms were distinguished based on the general appearance of the bundles of spines; one form possesses at least one bundle of stout spines, whereas bundles of medium spines or thinner acicular spines characterise the other forms. Differences in prostomial shape, as well as in the extension and form of the caruncle, were artefacts (preservation or angle of observation). The present study supports D. rogeri as a junior synonym of D. armata. D. armata was regularly found on shells inhabited by hermit crabs ( Calcinus tubularis , Clibanarius erythropus ) and on damaged, empty shells. Abundance, dominance, size frequency, occurrence of larvae and occurrence of regenerated specimens varied, possibly as a result of fouling strategy and recurrent settlements.     

Simplicissin,a New Pollen Growth Inhibitor Produced by the Fungus,Penicillium cf. simplidssimum (Oudemans) Thorn No. 410

A new pollen growth inhibitor, named simplicissin, was isolated from Penicillium cf. simplicissimum (Oudemans) Thorn No. 410, and its structure was established by spectroscopic methods including 2D NMR. The biological activities of the compound were examined by the bioassay methods involving tea pollen together with lettuce seedlings. The compound inhibited the growth of the tea pollen tube by 45% at a concentration of 3 mg/liter and showed complete inhibition at 10mg/liter.     

Lepidocoleus cf.ulrichi (Machaeridia) from the Trenton Group (Ordovician) of Ontario (Canada)

A specimen of the machaeridianLepidocoleus cf.ulrichi described herein focuses attention on taxonomical difficulties with extremely dorso-ventrally elongated sclerites found in some lepidocoleid taxa.Lepidocoleus ulrichi Withers, 1926 andLepidocoleus sigmoideus Withers, 1926 exhibit very similar appearances and prove indistinguishable based onWithers 1926 criteria. The key to separating taxa as similar as these may instead lie in the most juvenile stages of growth.