Tarmo Timm

New Species in the Old World: Europe as a Frontier in Biodiversity Exploration, a Test Bed for 21st Century Taxonomy

The number of described species on the planet is about 1.9 million, with ca. 17,000 new species described annually, mostly from the tropics. However, taxonomy is usually described as a science in crisis, lacking manpower and funding, a politically acknowledged problem known as the Taxonomic Impediment. Using data from the Fauna Europaea database and the Zoological Record, we show that contrary to general belief, developed and heavily-studied parts of the world are important reservoirs of unknown species. In Europe, new species of multicellular terrestrial and freshwater animals are being discovered and named at an unprecedented rate: since the 1950s, more than 770 new species are on average described each year from Europe, which add to the 125,000 terrestrial and freshwater multicellular species already known in this region. There is no sign of having reached a plateau that would allow for the assessment of the magnitude of European biodiversity. More remarkably, over 60% of these new species are described by non-professional taxonomists. Amateurs are recognized as an essential part of the workforce in ecology and astronomy, but the magnitude of non-professional taxonomist contributions to alpha-taxonomy has not been fully realized until now. Our results stress the importance of developing a system that better supports and guides this formidable workforce, as we seek to overcome the Taxonomic Impediment and speed up the process of describing the planetary biodiversity before it is too late.

Global diversity of polychaetes (Polychaeta; Annelida) in freshwater

A literature review of Polychaeta (Annelida) including Aphanoneura (the oligochaete-like Aeolosomatidae and Potamodrilidae), living in freshwater yielded 168 species, 70 genera and 24 families representing all of the major polychaete clades, but less than 2% of all species. The best-represented families were, in order, Nereididae, Aeolosomatidae, Sabellidae, Spionidae and Histriobdellidae. Fourteen families were represented by a single species and genus. Regions supporting the highest diversity of freshwater polychaetes were in order, Palaearctic, Neotropical, Oriental, Nearctic, Australasian, and Afrotropical. More than half of all species and genera inhabitat lakes and rivers, followed by lagoons/estuaries, which have a high proportion of euryhaline species, and inland seas. Less common, atypical polychaete habitats include subterranean waters, the hyporheic zone of rivers and plant container habitats (phytotelmata). At least three distinct ecological/historical processes appear to account for the colonisation of continental waters: invasion of a clade prior to the break-up of Gondwana, as in Aphanoneura, Namanereis, Stratiodrilus, and Caobangia; relatively recent stranding of individual species (relicts); and the temporary visitation of euryhaline species.

Indicative profundal oligochaete assemblages in selected small Swedish lakes

Fifty-seven small- to middle-size lakes of Sweden (size-range from <0.1 to about 200 km2) representing different regions and lake-types were selected for the purpose of demonstrating the indicative value of profundal oligochaete communities also of relatively small lakes. It is well known since previously that profundal oligochaete assemblages of large lakes in Europe may be particularly indicative of the current trophic situation, but little has been known about smaller lakes in this respect. Characterizations based on oligochaete community structure in these lakes could be summarized in eight different groups: Characteristic oligochaete communities in oligotrophic lakes of relatively small size are Spirosperma ferox, Stylodrilus heringianus and Tubifex tubifex. Oligochaete species richness is low (1–3 species) and so is species abundance (<300 specimens ċ m−2). Very eutrophic lakes of the same size-range are largely dominated by the tubificids Limnodrilus hoffmeisteri and/or Potamothrix hammoniensis. Substitute or complementary species may be T. tubifex. Species richness is usually low (1–3 species), but abundance is high to very high (>5000 specimens ċ m−2). Mesotrophic to moderately eutrophic lakes of the same size categories contain more species than the above extremes, most of them being fairly tolerant to oxygene deficiency such as Tubifex ignotus, a number of species of the genera Aulodrilus and Limnodrilus and a variety of so-called Ponto-Caspian Potamothrix species, most of them having recently invaded south-eastern Sweden. Species richness is moderate to high (4–8 species), while abundance may vary considerably (range from about 300 to about 5000 specimens ċ m−2). In this respect, small- to middle-size lakes do not differ much from larger lakes. For the trophic characterization of lake water the mean concentrations of total-phosphorus (in μg ċ l−1) is generally regarded to be the most appropriate measure. The match between characterizations based upon oligochaete community structure and total-phosphorus concentrations is generally very good for large lakes. The present study shows that this applies fairly well also to the majority of the small- to middle-size lakes selected for this study. This has not been shown before. Obvious deviations from this rule could be caused by a scarcity of reliable chemical data, or considerable seasonal shifts in the chemical composition ot the water, which in its turn may be caused by short water residence time. Littoral elements in the fauna, which are generally less indicative, or effects of local inflows may also be more frequent here than in lakes of larger size.

Distribution and dispersal capacity of the Ponto-Caspian tubificid oligochaete Potamothrix moldaviensis Vejdovský et Mrázek, 1903 in the Baltic Sea Region

Over the last few centuries, several Ponto-Caspian tubificid oligochaetes have gradually dispersed from the Black Sea – Caspian Sea region to the north-west and west over Europe. The present world distribution comprising also the Great Lakes of North America clearly demonstrates that anthropochorous vectors of dispersal are involved. Passive transportation in the ballast water of ships has radically changed the possibilities of dispersal for many invertebrate species and has even made dispersal between continents possible. The construction of navigable canals has furthermore facilitated the crossing of watersheds and continents. Other likely vectors of longway dispersal for oligochaetes, as well as for other small-size aquatic invertebrates, are birds and mammals. The dispersal of the Potamothrixspecies is likely to have taken place in successive waves (three) with front-lines still on the move from the east to the west over the Baltic States and Scandinavia. The rheophilous species Potamothrix moldaviensishas presently reached – apart from the large rivers of Russia and many Central-European water bodies – also the Baltic States and south-eastern Sweden. Trajectories of dispersal demonstrate routes across the Baltic Sea – via the ballast water of ships. In the largest rivers of the Eastern Baltic Region (Neva, Daugava, Nemunas), downstream dispersal is the most likely way of transportation. P. moldaviensis together with P. heuscheri(second wave) and P. vejdovskyi(third wave) are presently forming front-lines running obliquely from the north-east to the south-west over south Sweden. In mesotrophic-eutrophic basins of eastern Lake Mälaren, the abundance as well as the species diversity of oligochaetes is particularly high wherever Ponto-Caspian Potamothrixspecies – often several species together – are involved.

Potential age of aquatic Oligochaeta

The maximum lifetime of species with exclusively sexual reproduction covers 5–15 years or even more in aquaria, although most specimens die consecutively earlier. The zooids of paratomic species live some weeks or months, their clones usually less than a year, rarely for some years. In the species with facultative architomy (fragmentation) the clonal age also exceeds that of the individual, both lasting for several years. The actual lifetime of worms in nature may be shorter than in cultures.

Differential response of aquatic oligochaete species to increased nutrient availability - a comparative study between Estonian and Dutch raised bogs

To assess the effects of increased nutrient availability on aquatic oligochaetes in raised bogs, species assemblages were compared within and between fairly pristine raised bogs in Estonia and raised bog remnants in The Netherlands. Within the pristine bog landscape a distinct pattern in the species assemblage is present. In the most nutrient-poor water bodies, in the ombrotrophic raised bog, only the fragmenting, almost never mature, acid-tolerant species Cognettia sphagnetorum is present. In pristine Estonian raised bogs Nais variabilis, Lumbriculus variegatus and sexually reproducing species are limited to more minerotrophic water bodies, which have a higher decomposition rate of dead organic matter and, consequently, higher nutrient availability. With ten species the lagg zone is the most species-rich part of a pristine raised bog landscape. Most of these lagg zone species are not present in Dutch bog remnants as this part of the bog landscape has long been cultivated. Nais variabilis occurs in the Dutch bog remnants much more frequently than in Estonian bogs, whereas the frequency of C. sphagnetorum and L. variegatus is similar between both countries. These three species respond differently to the increased nutrient availability in The Netherlands, which could be linked to differences in their diets. In contrast to pristine bog pools, N. variabilis in Dutch raised bog remnants is present in water bodies not influenced by minerotrophic water. In Dutch raised bog remnants the occurrence of oligochaetes is not limited anymore by nutrient availability, due to the higher atmospheric nitrogen and sulphur loads in The Netherlands. Overall, it can be concluded that the degradation of Dutch raised bogs has resulted in the loss of both the nutrient-poor parts of the landscape and the special lagg conditions.

Clitellate diversity in Nationalstadsparken, an urban national park in Stockholm, Sweden

To increase the overall faunistic knowledge of Swedish Clitellata, a survey was performed in Nationalstadsparken, a mosaic of fresh and brackish waters, parklands alternating with remnants of natural biota, and areas of urban development, within the cities of Stockholm and Solna on the Baltic coast of Sweden (59° N, 18° E). One hundred and twenty-one species (113 Oligochaeta, 8 Hirudinea) were collected at 31 aquatic and 27 terrestrial or littoral localities; 49 species of Oligochaeta were found at the aquatic localities, 70 species at the terrestrial/littoral sites. Twenty-four species are new records for Sweden, and this urban national park thus features 64% of all non-marine clitellates known from the country. The result is consistent with a view that diversity is enhanced when human activities increase habitat complexity, even in areas in direct contact with a large city.

Distribution of freshwater oligochaetes in the west and east coastal regions of the North Pacific Ocean

Faunistic data available from 10 different regions were reviewed: Middle and South China (55 species of freshwater oligochaetes recorded); Amur Basin, Manchuria and Primor’e (86); Korean Peninsula (20); Japan, Sakhalin and Kuril Islands (77); Kamcatka Peninsula (42); Cukci Peninsula including the Anadyr Basin and Korjak Mountains (41); Alaska Peninsula (31); Southern Alaska and British Columbia (62); Washington, Oregon and California (119); Mexico (25). A total of 306 valid species of freshwater oligochaetes includes the branchiobdellidans, freshwater and amphibiotic enchytraeids and lumbricids, as well as some brackish-water representatives of freshwater genera. Among them, 61 species of Naididae (56 on the Asian, 35 on the American side; 30 species common for both coasts); 68 of Tubificidae (40, 45; 17); 2 of Propappidae (2, 0; 0); 43 of Enchytraeidae (16, 27; 0); 43 of Lumbriculidae (29, 17; 3); 4 of Haplotaxidae (3, 2; 1); 1 of Biwadrilidae (1, 0; 0); 5 of Lumbricidae (4, 1; 0); 79 of the five branchiobdellidan families (36, 43; 0). Endemicity at the species or even generic level on either side of the Pacific appears to occur in over 2/3 of the total number of species, being prevalent in Lumbriculidae, Enchytraeidae, Haplotaxidae, Biwadrilidae and Branchiobdellida, less expressed in Tubificidae and rare in Naididae. Most of the species common to both coasts of the North Pacific are widely distributed in the Holarctic, or appear cosmopolitan. A weak faunal exchange appears to have happened in the Bering Strait region (Alexandrovia ringulata, Tasserkidrilus americanus, Styloscolex opisthothecus, Lumbriculus olgae).

Half a century of oligochaete research in Estonian running waters

About 51 500 specimens from 1542 samples, collected over the years 1954–1975 and 1986–1999 in different running water bodies throughout Estonia, were identified. Tubificidae prevailed in the material, with Limnodrilus hoffmeisteri forming about 40%. This species was followed by the tubificids Tubifex tubifex, Potamothrix hammoniensis, Psammoryctides barbatus, L. udekemianus and Spirosperma ferox, the naidid Stylaria lacustris, and the lumbriculid Stylodrilus heringianus. Two main ecological assemblages were distinguished: the pelophilous assemblage, dominated by L. hoffmeisteri, and the psammophilous one, where usually P. barbatus was dominant. The relationships between different species and the chemical parameters of water were usually weak but in contrast, correlated well with sediment preferences. In organically enriched reaches, L. hoffmeisteri usually dominated. The fauna of the streams of the islands was poorer in species due to their small size rather than geographical isolation. Some recent antropochorous Ponto-Caspian invaders have only reached the lowermost reaches of the two largest rivers. Some brackish water species were found in the mouth of the Parnu River. No essential differences were found between the comparable sets of oligochaete samples collected in 1954–1975 and 1987–1997 in the Estonian running waters.

Chapter 21 – Clitellata: Oligochaeta

This chapter introduces the Oligochaeta annelids, here treated as a paraphyletic stem group of the class Clitellata separated from the Hirudinea, Acanthobdellida, and Branchiobdellida. It starts by considering the group in a phylogenetic and taxonomic framework, as well as in terms of geographical distribution and diversity. It then deals with the general biology of these worms in describing their anatomy, physiology, reproduction and life history. Ecological and behavioral aspects of Oligochaeta are next addressed through topics related to habitat distribution and limitations due to physiological constraints, feeding behavior, predators and parasites, competition, impact on the environment, and their use as organic pollution indicators. By the end of the chapter, the scientific study of the Oligochaeta is addressed via practical aspects such as collecting, culturing, and specimen preparation for identification.