Status of Biodiversity in the Baltic Sea

The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system''s diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity.     

Variation in the sublittoral macrozoobenthos of the Baltic Sea along environmental gradients: A functional-group approach

The enclosed Baltic Sea, one of the world’s largest brackish water basins, resembles a large estuary with steep horizontal and vertical environmental gradients. Thus, salinities range from 25 to 30 ppt in the Danish Sound area in the south to 1–3 ppt in the inner reaches of the Gulfs of Bothnia and Finland, and a persistent pycnocline in the Baltic basin causes stagnation of bottom waters for long periods, with periodic hypoxia/anoxia as a consequence, over an area covering up to 100 000 km². Further, climatic variation from boreal to subarctic causes additional stress on the ecosystem. In recent decades, eutrophication and pollution have also significantly affected the biota of the Baltic Sea. The soft bottom infauna is poor in terms of species composition, and functional complexity is considered to be low. This paper examines the estuarine soft bottom infauna of the Baltic Sea along some principal environmental gradients using a functional-group perspective. We have used the functional-group concept (primarily feeding type, mobility and microhabitat), designed for polychaetes by 22 , to analyze and illustrate if and how the environmental gradients are reflected in the zoobenthos. A total of 25 functional groups were identified, forming clines from complex functional communities in the south and west, towards functionally poor assemblages in the north and east. The shift in functional groups indicates a loss of carnivores, tentaculate sessile organisms, and burrowers from areas beyond the Baltic and its marine approaches towards the inner bays. On the other hand, suspension feeders and surface deposit feeders increase in importance. In the northernmost areas of the Baltic only 1–3 functional groups are found, compared to 8–20 in the south.     

Phytobenthos and macrozoobenthos of the Slupsk Bank stony reefs,Baltic Sea

The stony reefs of the Slupsk Bank were studied in July 1999 using hydroacoustic methods, underwater photography and video. Samples of macroalgae and associated fauna were collected by divers using a specially designed sampler. The results of the research indicate that this area is a unique site in the southern Baltic Sea. The high diversity of macroalgae and associated fauna, including the occurrence of three algal species endangered in the Polish coastal zone, is particularly of interest. The Slupsk Bank is also a feeding ground for many wintering birds. For these reasons, it is proposed that the site is designated as an open sea Helsinki Commission Baltic Sea Protected Area (HELCOM BSPA). It is also proposed that it is used as a reference area for ecosystem structure and ecotoxicological studies.     

Changes of the macrozoobenthos at 3 monitoring stations in the western Baltic Sea and the Sound

The soft bottom fauna of the western Baltic Sea and the Sound has been sampled and analysed every year since 1979 under the Baltic Monitoring Programme. Furthermore, benthos studies have been carried out in the area at intervals from as far back as 1871. In the area a distinct halocline exists between the overlying low saline Baltic water and the high saline North Sea water.The variation in the species richness, abundance and biomass of the soft bottom fauna is mainly related to 3 abiotic factors.First, many species live at the limit of their distribution. The low salinity of the Baltic Sea prevents their penetration into the Baltic proper. However, the marine species may be able to survive and grow but not to reproduce. Consequently, the population will depend on an influx of larvae for it's survival.Second, the distinct halocline prevents the transport of oxygen to the deeper parts of the Baltic Sea. Oxygen will be supplied under special weather conditions where inflow of high-saline oxygen rich North Sea water occur. The incidences of salt water inflow have increases in the last four decades.Third, an increasing load of the Baltic Sea with nutrients and organic matter has influenced the fauna. The result have been an increased biomass of the benthos above the halocline. Below the halocline the result has been a decrease in the biomass and a change in the species composition.     

Annual dynamics and production of rotifers in an eutrophication gradient in the Baltic Sea

Spatial and temporal fluctuations in rotifer abundance have been monitored along a trophic gradient in the northern Baltic. The most common rotifer was Synchaeta spp., which had one abundance peak in June and one in September–October. Only during the latter period was the abundance significantly higher in the eutrophic basin compared to the reference area. The annual production of Synchaeta spp. was about double in the eutrophic basin. A positive correlation between Synchaeta spp. biomass and phytoplankton biomass was obtained during the autumn, but not during the early summer peak, although the phytoplankton community was dominated by the same species. Keratella quadrata, K. cochlearis and K. cruciformis were most abundant in August–September, and all three species had increased abundance in the eutrophic basin.     

Uptake of dissolved organic nitrogen by size-fractionated plankton along a salinity gradient from the North Sea to the Baltic Sea

The Baltic Sea is known for its ecological problems due to eutrophication caused by high nutrient input via nitrogen fixation and rivers, which deliver up to 70% of nitrogen in the form of dissolved organic nitrogen (DON) compounds. We therefore measured organic nitrogen uptake rates using self produced ¹⁵N labeled allochthonous (derived from Brassica napus and Phragmites sp.) and autochthonous (derived from Skeletonema costatum) DON at twelve stations along a salinity gradient (34 to 2) from the North Sea to the Baltic Sea in August/September 2009. Both labeled DON sources were exploited by the size fractions 0.2–1.6 μm (bacteria size fraction) and >1.6 μm (phytoplankton size fraction). Higher DON uptake rates were measured in the Baltic Sea compared to the North Sea, with rates of up to 1213 nmol N l^?1 h^?1. The autochthonous DON was the dominant nitrogen form used by the phytoplankton size fraction, whereas the heterotrophic bacteria size fraction preferred the allochthonous DON. We detected a moderate shift from >1.6 μm plankton dominated DON uptake in the North Sea and central Baltic Sea towards a 0.2–1.6 μm dominated DON uptake in the Bothnian Bay and a weak positive relationship between DON concentrations and uptake. These findings indicate that DON is an important component of plankton nutrition and can fuel primary production. It may therefore also contribute substantially to eutrophication in the Baltic Sea especially when inorganic nitrogen sources are depleted.     

Diversity of Aphanizomenon flos-aquae (cyanobacterium) populations along a Baltic Sea salinity gradient

Colony-forming cyanobacteria of the genus Aphanizomenon form massive blooms in the brackish water of the Baltic Sea during the warmest summer months. There have been recent suggestions claiming that the Baltic Sea Aphanizomenon species may be different from Aphanizomenon flos-aquae found in lakes. In this study, we examined variability in the morphology and 16S-23S rRNA internal transcribed spacer (ITS) sequences of A. flos-aquae populations along a salinity gradient from a string of lakes to a fjord-like extension of the Baltic Sea to the open Baltic Sea. Morphological differences among the populations were negligible. We found that the Baltic Sea was dominated (25 out of 27 sequences) by one ITS1-S (shorter band of ITS 1 [ITS1]) genotype, which also was found in the lakes. The lake populations of A. flos-aquae tended to be genetically more diverse than the Baltic Sea populations. Since the lake ITS1-S genotypes of A. flos-aquae are continuously introduced to the Baltic Sea via inflowing waters, it seems that only one ITS1 genotype is able to persist in the Baltic Sea populations. The results suggest that one of the ITS1-S genotypes found in the lakes is better adapted to the conditions of the Baltic Sea and that natural selection removes most of the lake genotypes from the Baltic Sea A. flos-aquae populations.     

广东车八岭国家级自然保护区大型底栖动物多样性

大型底栖动物在当地生物多样性、食物链构成、水质指示和物质循环中有重要的作用, 但目前国内对森林内陆水体(湖泊、水库、溪流)中的大型底栖动物综合调查较少。作者于2019、2020年对广东车八岭国家级自然保护区的9个采样点开展了大型底栖动物的定性调查, 采样点涵盖保护区不同功能区、海拔、水体环境和水体底质。共鉴定出大型底栖动物4门6纲18目38科57种, 水生昆虫稚虫占大多数, 且多喜好清洁流动水体。在低海拔实验区即可采集到种类与数量可观的清洁水体指示物种。当地的大型底栖动物以亚热带森林典型物种为主, 多偏好栖息于流动水体, 反映了保护区的物种区系及其水体环境。本研究可为保护区的物种编目、环境评估和长期监测提供基础资料。     

Eutrophication in the Baltic Sea

Fish consumption is increasing globally. Overfishing puts pressure on fisheries, but aquaculture provides an alternative to satisfy the growing need for seafood. However, nutrient emissions from aquaculture contribute to eutrophication, and raising fish from the top of the food chain is inefficient. Here we use the approach of industrial ecology and report ImPACT decomposition analysis of the drivers of nutrient emissions to the Baltic Sea from rainbow trout aquaculture in Finland during 1980?2007. During this period, the nitrogen load studied increased markedly and was 522 tonnes in 2007. The phosphorus load quadrupled and then returned to its original level of about 65 tonnes. The Finnish population increased slightly, while the average affluence level increased significantly. Total salmonid consumption increased substantially during the period. The increasing percentage of imported salmonids and improvements in domestic aquaculture technology ended the period of strong growth of emissions in the 1980s. Decreasing the nutrient load through reductions in salmonid consumption in the future is unlikely, due to health benefits and consumer preferences. Replacing domestic production with import of salmonids raises questions regarding outsourcing of the environmental impact, and regarding rural development in Finland. Major improvements in production technology are not in sight. New perspectives on rainbow trout aquaculture may be needed, including using feed from the Baltic Sea, thus closing the nutrient cycle or changing consumption and production to herbivorous fish species.     

Species-specific phytoplankton sedimentation in relation to primary production along an inshore--offshore gradient in the Baltic Sea

The temporal and spatial variability in the quality and quantityof settling phytoplankton material in relation to concurrentprimary production was studied using sediment traps at threecoastal stations from a semi-enclosed bay (Pojo Bay) throughthe outer archipelago to the open Gulf of Finland. The fluxof settling phytoplankton was high (9.3 g C m^–2period^–1)in Pojo Bay, especially in spring, and lower in the archipelago(8.1 g C m^–2 period^–1) and open-sea area (5.2 gC m"2 period"1), although the primary production followed theopposite pattern. A large influx of allochthonous material intoPojo Bay in spring brought allochthonous phytoplankton cellsinto the traps, but limited primary production. Diatoms werethe most abundant settled phytoplankton at all stations, butthe species composition varied between Pojo Bay (Aulacoseiraspp., Rhizosolenia minima) and the outer stations (Skeletonemacostatum, Chaetoceros spp.)At the outer stations, migratingdinoflagellates (Peridiniella catenate) comprised part of thesettling material in spring. The high settling flux of the cyanophyteAphanizomenon flos-aquae is discussed. The species compositionof the phytoplankton assemblage influenced the proportion ofthe total organic carbon sedimentation that consisted of phytoplanktoncarbon.     

Biodiversity inventory and informatics in Southeast Asia

Rapidly changing land use in Southeast Asia threatens plant diversity, and reduces the time we have left to document it. Despite over 200 years of scientific plant exploration, many plant species have yet to be discovered. Moreover, we still have a very poor understanding of the distribution of known taxa in this biogeographically complex region. We review the current state of biodiversity exploration, using plants in Indonesia as an example. Traditional methods of collecting and describing species have provided a solid foundation for our understanding of plant biodiversity, but are insufficient for the pragmatic task of rapidly discovering and documenting today’s biodiversity before it is gone, because general collecting expeditions tend to be infrequent, and documentation of most new species must await taxonomic revisions many years in the future. Solutions to this exploration and documentation crisis (i) could use the abundant resource of enthusiastic, networked, national biology students, (ii) should employ biodiversity informatics tools to efficiently engage both specialists and parataxonomists, and (iii) might require adoption of new types of α-taxonomy, utilizing increasingly low-cost molecular methods and high resolution photographs. We describe emerging technologies that will facilitate this taxonomic development. We believe that a new golden age of biodiversity exploration may be dawning, just as biodiversity itself is most threatened, and are hopeful that increasing knowledge of biodiversity will be a positive force to slow its loss.     

An assessment of the biomass production theory in the Baltic Sea using fish landings data

Fish landings in the Baltic Sea from 1970 to 2000 were used as a proxy for fish biomass to explore variability of total fish biomass. Total demersal (total D) and total pelagic (total P) landings proved relatively invariant over time compared with most of their component species. This was explained in terms of the energy limitation imposed on the ecosystem by its carrying capacity, forcing species interactions (predation, competition, etc.) with compensations that allowed the total biomasses to remain relatively stable. Extensive interactions were demonstrated among the Baltic fish species by linear correlation with appropriate negative signs, indicating compensatory interactions consistent with the energy limitation theory. The variances of the landings of cod, herring, sprat and total landings reflected the magnitudes of variation of their biomasses as estimated from the Virtual Population Analysis (VPA), thus justifying the use of landings data in this analysis as a proxy for biomass. Significant demersal–pelagic coupling was indicated from the landings data, which could be explained by trophic interactions. Species interactions generally explained between 17 and 66% of the variations in landings. Thus, substantial portions of the variations in the landings must be attributed to other factors: biological, fishery and environmental.     

Biodiversity,conservation and inventory: why insects matter

Western culture views insects and arachnids as pests and vermin that need to be controlled. They usually are not considered as something to be preserved. Accordingly, arthropods and other small organisms have not been taken seriously for conservation by policy makers and the conservation community at large. Having existed for more than 400 million years and after surviving the Permian and Cretaceous mass extinctions, arthropods have been the most successful of all living things and along with other invertebrates constitute more than three-quarters of today's global biodiversity. Arthropods are major components of diverse ecosystems and are the major players in functioning of ecosystem processes. Nevertheless, arthropods, which are the least known and, along with other plants and animals, are relentlessly vanishing before our eyes. Thus, aside from anthropocentric perception and societal prejudice, arthropods certainly are not pests in an ecological or evolutionary context and have an inherent biological right to exist in an evolutionary context, with ecological and instrumental values. They must be preserved because of their inherent values but also because we need them for human survival. Thus, arthropods must become an important and necessary part of the conservation strategy at all levels of environmental organization, from populations and species to ecosystems and landscapes.Insect conservation aims at saving both endangered species and ecosystem processes with a multitude of approaches targeted at different scales. Conservation efforts for arthropods are daunting because all the odds are against them: whereas species diversity, population size and biomass are so large, taxonomy and faunal information are inadequate; whereas the need for taxonomic and biodiversity information increases greatly, the shortage of taxonomic expertise worsens.Basic issues of biodiversity and the loss of species are reviewed. The goals and strategies for insect conservation are discussed with a focus on inventory and monitoring. Taxonomic and environmental surveys are compared, and the needs for biodiversity monitoring are discussed as ecological monitoring process based on inventory data. This monitoring focuses on the health of nested biodiversity (composition, structure and process) and the state of species, differing from other contemporary monitoring efforts.     

Rhizopusmycosis in a harbor porpoise from the Baltic Sea.

A case of systemic mycosis due to a Rhizopus sp. infection is described in a dead-stranded, 10-yr-old, male harbor porpoise (Phocoena phocoena) found on the beach of Neustadt, Schleswig-Holstein on the Baltic Sea (Germany). At necropsy, granulomatous mycotic lesions in brain, lung, kidneys, testis, and draining lymph nodes were found. In addition, a focal ulcerative gastritis of the first stomach, due to a nematode infection, was present and is suspected to be the portal of entry for the fungus.     

From Sea to Sea: Canada's Three Oceans of Biodiversity

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada''s three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada''s three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada''s natural heritage.