Regular and irregular events in fouling communities in the White Sea

Patterns of long-term changes in fouling communities developing on artificial substrates in the White Sea are reviewed. The most significant shifts occurring in these communities are caused by biological successions that can last for several decades. Terminal stages of succession are the communities of a mussel Mytilus edulis or a solitary ascidian Styela rustica which can periodically replace one another within a narrow range of depths: from 1–1.5 to 5 m. Sporadic local invasion of a sponge Halichondria panicea can transiently modify the composition and performance of fouling communities. Sudden invasion of species that are not a typical component of fouling communities (infaunal polychaetes and molluscs, crabs) is not rare phenomenon but these organisms do not play a significant role there. Representatives of the associated polychaete fauna in fouling communities show long-term cyclic fluctuations in their abundances. Duration of these cycles is 7–8, 11–14, or 20 years.     

Long-term dynamics of the abundance of several intertidal polychaetes in two inlets of Kandalaksha Bay (White Sea)

Based on eigenvector filtering and phase surface methods, the correlation between abundance dynamics and water temperature was studied in seven species of White Sea littoral polychaetes. Cyclic fluctuations in abundance with periods of approximately 5 and 12 years were revealed. Some instances of the 5-year cycles of abundance can be explained by climatic changes in the Arctic.     

Long-term dynamics of main mesozooplankton species in the central Baltic Sea

Long-term dynamics (1959–1997) of the copepod speciesPseudocalanus elongatus, Temora longicornis, Acartia spp. andCentropages hamatus, as well as the taxonomic group of cladocerans,are described for the open sea areas of the central Baltic Sea.Differences between areas, i.e. Bornholm Basin, Gdansk Deepand Gotland Basin, as well as between 5 year periods, were investigatedby means of Analysis of Variance (ANOVA). No significant differencesin mesozooplankton biomass between areas were found. On theother hand, clear time-trends could be demonstrated and relatedto salinity and temperature, with P.elongatus biomass mainlydependent on salinity and T.longicornis, Acartia spp. and cladoceransbiomasses dependent, to a large extent, on thermal conditions.Decreasing salinities since the early 1980s due to a lack ofmajor inflows of highly saline water from the North Sea andincreased river run-off, both triggered by meteorological conditions,obviously caused a decrease in biomass of P.elongatus. Contrarily,the standing stocks of the other abundant copepod species andcladocerans followed, to a large degree, the temperature developmentand showed, in general, an increase. The shift in species compositionduring this period is considered to be a reason for decreasinggrowth rates of Baltic herring (Clupea harengus) since the early1980s, and for sprat (Sprattus sprattus) since the early 1990s.Generally, it is suggested that low mesozooplankton biomassesin the 1990s were caused, at least partially, by amplified predationby clupeid fish stocks.     

污损性管栖多毛类生态特点及研究展望

污损性管栖多毛类属环节动物门,主要由龙介虫科(Serpulidae)、螺旋虫科(Spirorbidae)、缨鳃虫科(Sabellidae)和蛰龙介科(Terebllidae)4科55种组成,以华美盘管虫(Hydroides elegans)、内刺盘管虫(H.ezoensis)、龙介虫(Serpula vermicularis)和克氏无襟毛虫(Pomatoleios kraussii)等种类为优势种,通常成批的附着在物体表面,严重影响人工设施的安全和性能。污损性管栖多毛类的分布具有明显的地域性和季节性,并与深度有关。今后工作应进一步开展管栖多毛类基础生物学研究,探讨外来种的入侵及影响,丰富和发展生态和分类等方面的研究内容。     

Long-term population dynamics of breeding bird species in the German Wadden Sea area

For no other group of organisms in coastal areas are there so exact and long-term data available as there are for seabirds. Since the beginning of the 20th century, documentation of population size, especially for species breeding in colonies from the groups gulls, terns and auks, is almost complete. These species act as bio-indicators, and data on fluctuations in their population size are useful as they reflect changes in the state of the marine ecosystem. The population development of some of these seabird species (Herring Gull, Guillemot, Common, Arctic and Sandwich Tern) from the German North Sea coast, which primarily feed on fish, is given. Common to all these species is an exponential increase in numbers in recent years (1970–1985). Possible causes for this development, e.g. pressure from enemies or competitors, availability of breeding places, anthropogenic stress and mortality factors, as well as the direct and indirect anthropogenic-influenced changes in the trophic system due to the increasing eutrophication of coastal waters, are evaluated. Signs of a collapse in the stocks of seabrids resulting from environmental pollution are discussed. Consequences resulting from the ecosystem changes, such as reduction of nutrient discharge into the North Sea and the expansion of biological monitoring, are described. Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland, Wattenmeerstation Sylt, D-2282 List, FRG, 1–4 November 1988)     

Seasonal dynamics of the numbers of larvae of common fouling organisms in Balaklava Bay (Black Sea)

The seasonal dynamics of the numbers of larvae of common fouling organisms—the barnacle Balanus improvisus and the bivalves Mytilaster lineatus and Mytilus galloprovincialis in Balaklava Bay (Black Sea)—were investigated during 2000 and 2001 within the framework of an ecological research project. Under the conditions of an increased anthropogenic load, seasonal fluctuations of the numbers and the distribution of larvae depend on rhythms of the breeding cycles of fouling invertebrates and on the hydrodynamic features of the region (water setup). The differences in the optimum temperatures, hatching intensity, and time of occurrence of larvae in the plankton, as well as the irregular distribution of larvae, allow the three major fouling organisms to reduce interspecific competition for food and the substrate.Original Russian Text Copyright © 2004 by Biologiya Morya, Shalaeva, Lisitskaya.     

Resistance of larvae of common species of White Sea invertebrates to extreme changes in salinity

This study examines the effect of sharp changes in salinity on pelagic larvae of ten common species of invertebrates from the brackish White Sea (Mollusca, Polychaeta, Echinodermata, Cnidaria, Ascidia). For five species, the low salinity resistance limit was in the range of 8–12‰: for the gastropod Littorina littorea, it was below 8‰; for Dyaphana sp. and the bivalves Hiatella arctica and Heteranomia ovata, it was more than 12‰; and for the ascidian Styela rustica, it was 16‰. About 50% of larvae of four investigated species were able to withstand high salinity and survived at 36–40 and even 50‰ (Littorina). Larvae of littoral-sublittoral species proved to be more euryhaline than larvae of sublittoral species.     

Long-term dynamics of zooplankton in the southeastern Baltic Sea

Long-term research in the Baltic Sea revealed the basic trends of zooplankton community variations depending on oceanographic processes. Alternation of the periods of increase and decrease in salinity of the Baltic Sea against the background of climate changes (temperature increase) and eutrophication affect the state of the entire Baltic ecosystem, including zooplankton. For these periods, the dynamics of zooplankton in the Baltic Sea were analyzed based on literature data and results of regular research in the southeastern Baltic Sea during 1998–2007. The changes in the hydrological situation were accompanied by significant changes in the zooplankton community. In the 1990s–2000s, the abundance and biomass of brackish-water and thermophilous species primarily of Cladocera and Copepoda increased markedly. The role of the previously dominant marine copepod Pseudocalanus elongatus decreased due to salinity reduction in the deep-water part of the Baltic Sea. Maximum development of zooplankton occurred in years of the greatest warming-up of the water (2001, 2005–2007) against the background of a general positive trend of zooplankton abundance in the last decade.     

The structure and long-term dynamics of the communities of Arctica islandica (Bivalavia) in Rugozerskaya Guba of the White Sea

The age structure of a dense settlement of Arctica islandica (Bivalvia) near Vysokii Island (Rugozerskaya Guba (bay)) of the White Sea is described. The data collected by trawling in 2003, 2006–2007 and grab sampling in 2009–2011 are summarized. The A. islandica community in the Rugozerskaya Guba was first described in 1953–1959, but to date, no reliable quantitative estimates have been obtained and the community’s size structure was not studied. The size structure of this community was stable over the last eight years; the main part of the community was represented by individuals with a body weight of 3–10 g. It was revealed that the distribution of different A. islandica classes depends on the depth. The majority of the largest individuals were found in the shallowest parts of the study area (9–11 m); middle-size individuals were registered at depths of 9–14 m; and the smallest ones, at depths of 12–17 m.     

A comparative study of the pumping activity of some fouling animals from the White Sea

The pumping activity of the bivalve Mytulus edulus, Hiatella arctica, and solitary ascidian Styela rustica from the White Sea has been studied. The dependence of the pumping activity on the mass and size of animals has been analyzed. It was shown that the mussel is the most active filter-feeder, that the least value of the pumping activity has been registered for H. arctica, and that S. rustica occupies an intermediate position according this index. The results obtained are examined in connection with the competitive relationship of the animals in the fouling community.     

Estuarine fouling communities are dominated by nonindigenous species in the presence of an invasive crab

Interactions between anthropogenic disturbances and introduced and native species can shift ecological communities, potentially leading to the successful establishment of additional invaders. Since its discovery in New Jersey in 1988, the Asian shore crab (Hemigrapsus sanguineus) has continued to expand its range, invading estuarine and coastal habitats in eastern North America. In estuarine environments, H. sanguineus occupies similar habitats to native, panopeid mud crabs. These crabs, and a variety of fouling organisms (both NIS and native), often inhabit man-made substrates (like piers and riprap) and anthropogenic debris. In a series of in situ experiments at a closed dock in southwestern Long Island (New York, USA), we documented the impacts of these native and introduced crabs on hard-substrate fouling communities. We found that while the presence of native mud crabs did not significantly influence the succession of fouling communities compared to caged and uncaged controls, the presence of introduced H. sanguineus reduced the biomass of native tunicates (particularly Molgula manhattensis), relative to caged controls. Moreover, the presence of H. sanguineus favored fouling communities dominated by introduced tunicates (especially Botrylloides violaceous and Diplosoma listerianum). Altogether, our results suggest that H. sanguineus could help facilitate introduced fouling tunicates in the region, particularly in locations where additional solid substrates have created novel habitats.     

Spatio-temporal dynamics of species richness in coastal fish communities

Determining patterns of change in species richness and the processes underlying the dynamics of biodiversity are of key interest within the field of ecology, but few studies have investigated the dynamics of vertebrate communities at a decadal temporal scale. Here, we report findings on the spatio-temporal variability in the richness and composition of fish communities along the Norwegian Skagerrak coast having been surveyed for more than half a century. Using statistical models incorporating non-detection and associated sampling variance, we estimate local species richness and changes in species composition allowing us to compute temporal variability in species richness. We tested whether temporal variation could be related to distance to the open sea and to local levels of pollution. Clear differences in mean species richness and temporal variability are observed between fjords that were and were not exposed to the effects of pollution. Altogether this indicates that the fjord is an appropriate scale for studying changes in coastal fish communities in space and time. The year-to-year rates of local extinction and turnover were found to be smaller than spatial differences in community composition. At the regional level, exposure to the open sea plays a homogenizing role, possibly due to coastal currents and advection.     

Long-term dynamics of species composition and abundance of flatfish in waters off Primorye (the Sea of Japan)

Based on the data of trawl surveys, changes in the structure of species composition and flatfish abundance (Pleuronectidae) in waters off Primorye are shown in the period embracing over 20 years (1983 to 2004). In waters off Primorye, 14 flatfish species were recorded in catches. At the present time, the structure of the flatfish part of the fish community in waters off Primorye has undergone considerable changes in comparison with the 1980s: the proportion of deepwater flatfish has considerably increased against the background of a decrease in the abundance of coastal species. A general decrease in the numbers and biomass of flatfish in waters off Primorye is recorded, which is caused by natural reasons against the background of an inconsiderable fishery intensity.     

Temperature,space availability,and species assemblages impact competition in global fouling communities

Competition drives community composition in many ecosystems and can influence the spread of invasive species. Marine fouling communities are excellent study systems for competition because of space limitation and the abundance of invasive species. While many studies have examined individual or site-specific responses to changes in temperature or presence of invasive species, it is difficult to predict ecological impacts without assessing interspecific interactions over a wide geographic range. This study compared interactions between several globally distributed invasive fouling species over a broad geographic range. Weekly examination of photographs of settlement panels in marinas at 18 sites around the world allowed for the quantification of competitive outcomes. In the north Atlantic, experimental panels became covered with fouling organisms exponentially faster at warmer temperatures, while northeast and south Pacific sites did not. An invasive ascidian (Diplosoma listerianum) and bryozoan (Bugula neritina) were strong competitors, but most species displayed a negative response in high competition settings where there was little available space. Two species (Botryllus schlosseri and Botrylloides violaceus) had better competitive outcomes at cooler temperatures, possibly due to fewer strong competitors at these sites. Thus, warmer sites with little open space and multiple strong competitors are likely most resistant to future invasions, while colder sites with more open space and weaker competitors would be more susceptible to invasive species. These results suggest that the establishment and spread of invasive fouling species is likely to be influence by seawater temperature, available space, and the competitive abilities of community members.     

Bioerosion features of boring polydorid polychaetes in the North Adriatic Sea

Hydrobiologia - Considering the pivotal role played by erosive organisms in the marine habitat and the scanty knowledge of this phenomenon in the Mediterranean Sea, the present study aimed to...     

Long-term changes in the benthic communities of the Pomeranian Bay (Southern Baltic Sea)

Long-term changes in the macrofauna of the Pomeranian Bay were studied by comparing survey data from the 1950s, 1980s, and 1990s. The study area has undergone significant eutrophication during the period of investigation. Biomass of filter-feeding bivalves increased significantly. Spatial distribution patterns of several species have changed. Strong decreases in species richness were caused by oxygen depletion at stations deeper than 15 m.Saduria entomon, Monoporeia affinis, andPontoporeia femorata vanished entirely between 1981 and 1993. Although a causal relationship between simultaneous increases of nutrient levels and macrobenthic biomass cannot be verified, eutrophication is proposed to be the major process affecing changes in macrofauna assemblages. In addition, changes in hydrography and climate increased frequency and severity of oxygen depletion events in the Pomeranian Bay since the mid 1980s.     

Long-term recruitment dynamics of arctic dwarf shrub communities in coastal east Greenland

Warming-induced biological and ecological responses have been reported from high-northern latitude sites, where changes in dwarf shrub communities translate into complex vegetation-climate feedbacks. Most of the available Arctic tree-ring evidence is, however, restricted to a limited number of species and locations. A combination of wood anatomical and ‘dendro’-ecological techniques provides insights into past growth rates, recruitment dynamics and even community assemblages of Arctic vegetation. Here, we use thin sectioning and ring counting of 1432 dwarf shrub samples from eight species and two tundra regions in coastal east Greenland to assess community recruitment history and its relation to climate. Site and species-specific annual stem increments, as well as estimated plant ages, range from 0.013-0.720 mm and from 4 to 204 years, respectively. The mean ring width is 0.086 mm, with a mean age of 50 years. Decadal-scale recruitment dynamics of the studied vegetation cover respond to Greenlandic summer temperature variations back to the late 19th century (r = 0.7; 1881–2000).