Ralf Thiel

• Prof. Dr.
• former Curator of Fishes at Leibniz Institute for the Analysis of Biodiversity Change

Food webs in estuarine ecosystems serve as important biological indicators. The feeding ecology of four keystone fish species, pikeperch (Sander lucioperca L.), smelt (Osmerus eperlanus L.), ruffe (Gymnocephalus cernua L.) and flounder (Platichthys flesus L.), in the Elbe and Odra estuaries was analyzed using stomach content analyses. Important pre...

A new species of liparid fish from the genus Osteodiscus Stein, 1978 is described. The genus is primarily distinguished from Careproctus Krøyer, 1862 in the reduction of soft tissues of the pelvic disk. Three specimens of Osteodiscus lindbergi sp. nov. were caught during the international expedition SokhoBio (“Sea of Okhotsk Biodiversity Studies”,...

Species of the genus Zenarchopterus are marine, brackish, and freshwater fishes that have modified dorsal-fin and anal-fin rays in adult males. There are 19 valid species worldwide. Three species have been recorded from Taiwan, namely Zenarchopterus buffonis (Valenciennes, in Cuvier & Valenciennes, 1847), Z. dispar (Valenciennes, in Cuvier & Valenc...

Coastal marine and estuarine systems are subject to enormous endogenous and exogenous pressures, particularly climate change, while at the same time being highly productive sources and nurseries for fish populations. Interactions between host and microbiome are increasingly recognized for their importance for fish health, with growing evidence indi...

The deep-sea snailfish Careproctus bathycoetus Gilbert et Burke, 1912 was described a century ago from a single specimen caught at a depth of 3292 m in the Kuril Basin (southern Sea of Okhotsk, western North Pacific). Until now, it was known from the holotype only. Therefore, the capture of another specimen is of great interest and provides new dat...

Coastal marine and estuarine systems are subject to enormous endogenous and exogenous pressures, particularly climate change, while at the same time being highly productive sources and nurseries for sh populations. Interactions between host and microbiome are increasingly recognized for their importance for sh health, with growing evidence indicati...

Coastal and estuarine environments are under endogenic and exogenic pressures jeopardizing survival and diversity of inhabiting biota. Information of possible synergistic effects of multiple (a)biotic stressors and holobiont interaction are largely missing in the Elbe estuary but are of importance to estimate unforeseen effects on animals’ physiolo...

Although Ipnops specimens are relatively common in the Clarion-Clipperton Fracture Zone (CCZ), an area targeted for potential future deep-sea mining, a reliable species identification has not yet been possible due to the lack of a captured specimen. In April 2012, an Ipnops specimen was caught for the first time from the eastern CCZ during an explo...

Feeding ecology and growth of juvenile zander in the Elbe and Odra estuaries

Concerns about Anguillid herpesvirus 1 (AngHV‐1) in European eels, especially due to stocking measures, is increasingly coming into focus and raises questions regarding disease monitoring and prevention. In the past, stocking of AngHV‐1‐positive eels into waters assumed AngHV‐1‐free has led to a rapid increase of infected eels in the wild. For this...

This report describe the first application of environmental DNA‐metabarcoding approach for the assessment of fish species diversity in two marine protected areas of the North Sea: the Doggerbank and the Sylt Outer Reef. We collected 64 water samples and detected 24 fish species. We discuss qualitative differences between MPAs and compare the result...

Etmopteridae (lantern sharks) is the most species-rich family of sharks, comprising more than 50 species. Many species are described from few individuals, and re-collection of specimens is often hindered by the remoteness of their sampling sites. For taxonomic studies, comparative morphological analysis of type specimens housed in natural history c...

The Nordic Seas have one of the highest water-mass diversities in the world, yet large knowledge gaps exist in biodiversity structure and biogeographical distribution patterns of the deep macrobenthic fauna. This study focuses on the marine bottom-dwelling peracarid crustacean taxon Cumacea from northern waters, using a combined approach of morphol...

Harmonizing biodiversity assessments under the Marine Strategy Framework Directive (MSFD) at the pan-European level is a crucial task for the Regional Sea Conventions and EU Member States in the coming years, particularly for fish assessment in Descriptor 1 (biodiversity). Precondition for coherent fish assessments is the establishment of a regiona...

This study focuses on the marine bottom-dwelling peracarid crustacean taxon Cumacea from northern waters, using a combined approach of morphological and molecular techniques to present a first insight into genetic variability of this taxon. In total, 947 specimens were assigned to 77 morphologically differing species, representing all seven known f...

A new species of eelpout genus Pachycara Zugmayer, 1911 is described based on five specimens caught at a depth of 2419–3275 m along the Central and Southeast Indian Ridges in the Indian Ocean. The specimens were collected during the INDEX cruises in 2016, 2018 and 2019, respectively. The new species is distinguished from its congeners by the follow...

The Elbe is one of the longest European rivers and features a large, turbid and well-mixed estuary, which runs through the inner city of Hamburg. The Elbe has been closely monitored using classical catch techniques in the past. Here we tested a COI-based eDNA approach for assessing the biodiversity within the Elbe. We sampled three stations in the...

The maraena whitefish Coregonus maraena is a threatened anadromous species in the North Sea, which in the past was decimated to near extinction. Since the late 1980s, several re-establishment programs have been implemented in rivers draining into the North Sea, but the scientific basis for sustainable conservation measures is often lacking, since l...

Urotrygon chilensis (Günther, 1872) was described based on a single specimen acquired by the British Museum of Natural History, London, from the Johan Cesar Godeffroy Museum in Hamburg. This medium-sized, benthic stingray is found along the eastern Pacific shelf (distance ranging almost 7000 km). During the last century, it has been frequently ment...

Four new species of Careproctus (Cottoidei: Liparidae) are described from the Bussol Strait (the deepest channel of the Kuril archipelago) and two neighboring abyssal basins of the Western North Pacific. Careproctus laperousei sp. nov. from the northern slope of the Kuril-Kamchatka Trench (depths of 4796–4803 m) has the following characters: verteb...

The topic of the poster deals with the bioaccumulation potential of the chemically marker Alizarin red S (ARS) in eel muscle tissue. In this study, on the one hand, a detection method was developed to determine ARS in fish tissues and, on the other hand, the ARS concentration in 250 eels was analyzed.

For fish stock management and large-scale stocking programs, the chemical substance alizarin red S (ARS) is an important tool to mark fish permanently. Equally, for the IUCN red list species European eel (Anguilla anguilla), ARS is proven to be the most promising option for mass marking. ARS binds to calcified structures (i.e., bones and otoliths)...

The anadromous smelt Osmerus eperlanus (Linnaeus, 1758) is considered as a key species in the Elbe estuary. Here, the smelt plays an important role in the food web due to its high abundance and biomass (THIEL 2001). Over the last five years, a decrease of the smelt stock was observed in the tidal Elbe River. The estuary of the Elbe is considered to...

A new deep-water catshark, Bythaelurus stewarti, is described based on 121 examined specimens caught on the Error Seamount (Mount Error Guyot) in the northwestern Indian Ocean. The new species differs from all congeners in the restricted distribution, a higher spiral valve turn count and in the morphology of the dermal denticles. It is distinguishe...

Stocking of farmed eels is a commonly used management measure across Europe, and partly Asia, to supplement local stocks that chronically suffer from poor recruitment. During the farming process, increased growth and stress-related annulus-like rings are formed, which have been hypothesised to bias ageing and growth estimation. Alizarin red S (ARS)...

The recruitment of the European eel stock has collapsed and the stock is in a perilous state compared to the reference period between 1960 and 1979. Despite extensive European Union wide stocking efforts towards a stock recovery and a self-reproducing stock, recruitment stagnates at historical low levels. The aim of this study was to compare the mo...

Langzeitbeobachtungen von aquatischen Ökosystemen zeigen nicht nur eine hohe Variabilität, sondern auch graduelle Änderungen und sog. Regimeshifts: sprunghafte Änderungen im Funktionieren des gesamten Ökosystems. Sowohl die natürliche Variabilität hydrodynamischer und atmosphärischer Prozesse auf verschiedenen Zeitskalen als auch menschliche Einflu...

We studied diet, growth and reproductive biology of round goby Neogobius melanostomus from the Kiel Canal, northern Germany, to give an insight into the life cycle of this species in a brackish water canal. Crustaceans had the highest importance in the diet of all examined size classes of round goby. Other major food taxa were annelids and chironom...

A new species of eelpout genus Lycenchelys Gill, 1884 is described based on seven specimens caught at a depth of about 2350 m in the Bussol Strait, southwest of the Kuril Island Simushir. The species differs from its congeners in the following combination of characters: vertebrae 26–28 + 100–102 = 126–130; interorbital and occipital pores absent; p...

This study presents a new chemical double-marking technique for European glass eels Anguilla anguilla by combing alizarin red S (ARS) and strontium chloride hexahydrate (Sr). Marked eels (double marked with ARS and Sr, but also single marked with ARS) were exposed in situ to brackish water (15 g l−1 artificial sea salt) for 14 days and did not exhi...

The Schlei fjord in northern Germany is the recipient water of a comprehensive eel, Anguilla anguilla (L.), stocking programme. Since 2015, stocked eels become alizarin red S marked, but to date no control mechanism is implemented in this stock enhancement measure to prevent anthropogenic spreading of diseases. Consequentially, it was possible that...

The Working Group on Eel of the International Council for the Exploration of the Sea (ICES) regularly reports that a significant amount of stocked eels in Europe was pregrown in aquaculture farms prior to stocking—so called “farmed eels.” The ICES advices chemical marking of stocked recruits to ensure their traceability throughout all life stages....

Im Zeitraum von Juli 2013 bis Februar 2016 wurden im Rahmen dieses Vorhabens historische und aktuelle Daten zum Vorkommen von Knorpelfischarten in Nord-und Ostsee zusammengetragen und ausgewertet. Der Schwerpunkt der Analysen lag dabei auf den in deutschen Meeresgebieten von Nord-und Ostsee nachgewiesenen Arten. Für diese Knorpelfischarten wurden E...

We report the most northerly occurrence of the bighead goby Ponticola kessleri (Günther, 1861) in the Elbe River in Germany, where the fish was first observed in August 2015. Previously, the northernmost record of this Ponto-Caspian gobiid species originated from the lower Rhine River. Twelve specimens of P. kessleri were recorded in the Elbe River...

Accurate stock assessments for each of the dominant species of sand lances in the northeast Atlantic Ocean and adjacent areas are not available due to the lack of a reliable identification procedure; therefore, appropriate measures of fisheries management or conservation of sand lances cannot be implemented. In this study, detailed morphological an...

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The Roughskin Dogfish Centroscymnus owstonii is one of the most widespread deepwater shark species, but its global distribution is mostly based on patchy records. In this study, C. owstonii was reinvestigated with focus on its poorly known distribution in the western and eastern Indian Ocean. Previous records of the species from the Seychelles, whi...

We inspected diet and growth of zander Sander lucioperca, a main predator in North European brackish waters, from the Kiel Canal, northern Germany, to analyse effects of the introduced round goby Neogobius melanostomus as possible prey. Round goby represented the most important fish prey taxon in the zander diet in 2011–2013 with 21.8% of relative...

A new dwarf deep-water catshark, Bythaelurus tenuicephalus, is described based on one adult and one juvenile male specimen from off Tanzania and Mozambique in the western Indian Ocean. The new species differs from its congeners by its slender head and snout, which is only slightly bell-shaped in dorsoventral view without distinct lateral indention....

Hypoxia has gained ecological importance during the last decades, and it is the most dramatically increasing environmental factor in coastal areas and estuaries. The gills of fish are the prime target of hypoxia and other stresses. Here we have studied the impact of the exposure to hypoxia (1.5 mg O2/l for 48 h) on the protein expression of the gil...

Prey choice of opportunistic piscivorous birds, such as Phalacrocoracidae, may primarily depend on prey abundance in rivers. Estuaries, the most downstream river stretches, often represent important feeding sites for piscivorous birds, but are usually characterised by highly dynamic fish assemblages. Thus, studies of the composition of diets of est...

A new species of the Indo-Pacific skate genus Okamejei is described based on 10 specimens caught around the Socotra Islands (northwestern Indian Ocean). The type series of Okamejei ornata n. sp. was sampled during cruise 17 of RV ‘Vityaz’ along the deep western Indian Ocean in 1988/89. The new species represents the fifth species of Okamejei in the...

The growth response of juvenile round gobies was tested in various salinities to assess the potential performance of the species in widely differing salinities in the Baltic Sea and adjacent waters. An experimental approach analysed the survival, daily food intake and growth of juvenile Neogobius melanostomus from the brackish water region of the K...

Chelidoperca investigatoris (Alcock, 1890) was described based on two specimens collected off the Madras coast (Tamil Nadu), Bay of Bengal and Chelidoperca occipitalis Kotthaus, 1973 was described from a single specimen collected off the Socotra Islands, Arabian Sea. In 2009-2010, many additional specimens of these two species were collected from o...

Gobies are difficult to identify, as they are very similar in appearance. Here, we identified (sub)adult specimens of 12 goby species from the North Sea and the Baltic Sea by carefully analysing meristic characters, coloration patterns, papillae row patterns and morphometric measurements. The results of the morphological identifications were congru...

Preliminary results of elasmobranchs recorded in German waters of the North and Baltic Seas are presented. Catch records were obtained by analysis of historical to current literature as well as original data gathered from relevant German museum collections. In addition to German institutions, data from northern European museums have also been integ...

A new species of the widely in temperate and tropical latitudes distributed skate genus Rajella is described based on an almost adult male specimen from the western Indian Ocean off South Mozambique. The holotype of R. paucispinosa n. sp. was caught during cruise 17 of RV ‘Vityaz’ along the deep western Indian Ocean in 1988/89. It is the northernmo...

a) In this paper table assignments are erroneous. The correct table assignments are given below: Table 5 Table 4 b) Assignment to Table 5 is missing. Table 5 assignment should be inserted in section "Influence of environmental variables", second paragraph, second sentence that should read as "Here, we evaluated data from official site (FGG Elbe 201...

The African dwarf sawshark Pristiophorus nancyae is one of the least known species of the genus. The species was described in 2011 based on type specimens in rather poor condition and with a very restricted distribution off southern Mozambique. Since nine further specimens in mostly excellent condition became available, the authors reinvestigated t...

There is still a great lack of information regarding spatial and temporal gradients of quantitative guild composi-tion of the fish fauna and their relation to environmental variables in European estuaries. To fill parts of this gap in knowledge, fish species densities in the Elbe estuary were estimated with high resolution using samples taken by a...

Anacanthobatis ori is one of the least known species of the family Anacanthobatidae with only four juvenile specimens reported. The species remained assigned to the genus Anacanthobatis sensu lato due to the lack of an adult male as external and skeletal clasper characters are the essential diagnostic features for the differentiation of genera and...

On a global scale, the frequencies and magnitudes of hypoxic events in coastal and estuarine waters have increased dramatically over the past 20 years. Fish populations are suitable indicators for the assessment of the quality of aquatic ecosystems, as they are omnipresent and often comprise a variety of different lifestyles and adaption strategies...

The round goby Neogobius melanostomus (Pallas, 1814), a Ponto-Caspian gobiid species, was recorded for the first time in the Elbe River, Germany in May 2008. Between then and June 2013, 22 records comprising 36 specimens of N. melanostomus have been collected from the Elbe River, mainly in the tidal river section of the city of Hamburg.

Knowledge about distribution and habitat requirements of species is important for analyzing their role in marine ecosystems or establishing sanctuaries. However, knowledge is scarce especially in many chondrichthyan species. In this study, the spatial distribution of the stingray Neotrygon kuhlii on the Australian North and Northwest Shelf was pred...

Individual migration behaviour during the juvenile and adult life phase of the anadromous twaite shad Alosa fallax in the Elbe estuary was examined using otolith Sr:Ca and Ba:Ca profiles. Between hatching and the end of the first year of life, juveniles showed two migration patterns. Pattern one exhibited a single downstream migration from fresh wa...

After a serious decline in the past, some twaite shad Alosa fallax populations have significantly recovered during the last decade. Although increasing numbers of the species occur in areas of the southern North Sea, detailed quantitative analyses have not been published on spawning stocks of specific North Sea estuaries. In this study, the develop...

A new deep-sea fish is reported for the tropical eastern Atlantic. The rare chiasmodontid Kali macrodon was caught for the first time in Cape Verdean waters during an oceanographic survey in September 2009. This record provides the fifth occur- rence for the species in the north-eastern Atlantic and represents the third specimen ever caught in trop...

A new genus and species of the carcharhiniform family Pseudotriakidae is described based on three specimens caught near the Socotra Islands in the northwestern Indian Ocean. The first specimen and holotype of Planonasus parini g. n. and sp. n. was caught during cruise 17 of RV 'Vityaz' in 1988/89 along the deep western Indian Ocean. Two further spe...

The naked goby Gobiosoma bosc (Lacepède, 1800), a western Atlantic gobiid species, has been recorded for the first time in European waters in October 2009. Seven specimens were caught by a stow net vessel at river km 45 in the Weser estuary (Germany) close to Sandstedt.

We analysed ~310 records of river lampreys Lampetra fluviatilis (Linnaeus, 1758) (~19977663 specimens) and 54 records of sea lampreys Petromyzon marinus Linnaeus, 1758 (~86 specimens) for the southern parts of ICES Subdivisions 22 and 24 to 26 in the Baltic Sea covering the period 1649 to 2005. Most sea lamprey records came from Subdivisions 22 and...