Franz Uiblein

Complex patterns of colonization and refugia revealed for European grayling Thymallus thymallus , based on complete sequencing of the mitochondrial DNA control region

The complete mitochondrial DNA (mtDNA) control region (1043 base pairs) and 162‐bp of flanking transfer RNA genes were sequenced in 316 European grayling, Thymallus thymallus, from 44 populations throughout the Western European range of the species. A total of 58 haplotypes were revealed with pairwise divergence ranging from 0.001 to 0.038. An inferred intraspecific phylogenetic tree revealed two well‐supported clades within the Danube basin, one highly divergent clade in the Adriatic basin, and one large, diverse group representing most other populations. A deeply divergent haplotype fixed in the Loire basin in central France, more groups of haplotypes from distinct Danubian tributaries, and a relatively ancestral haplotype fixed in former tributaries of the Elbe in Denmark all suggest a complex pattern of interglacial and postglacial expansions originating from disjunct refugia throughout central Europe. Despite some evidence of human‐mediated stock transfers, parsimony‐network‐based nested‐clade analysis (NCA) supported specific inferences relating to corridors of postglacial expansion such as the lower Rhine (Moselle) and Elbe systems (Danish populations) serving as sources for expansion into the Baltic to the north as well as the upper Rhine and Danube to the south; and specific Rhine populations (Doller, Orbe and Reuss) serving as sources for colonization of the Rhone. The multiple divergent clades representing populations in the upper Danube, as well as the deeply divergent haplotypes found in the Adriatic and Loire basins (> 5% divergence from Asian outgroups) support the theory that European grayling have had a long history in Western Europe, pre‐dating Pleistocene glacial cycles. The patterns of mtDNA divergence shown here support a perspective of rich inter‐ and intrabasin genetic diversity that should be protected from current trends to translocate brood stocks for rearing and release in response to declining populations, especially in southern European basins.

Goatfishes (Mullidae) as indicators in tropical and temperate coastal habitat monitoring and management

Abstract This review investigates if goatfishes qualify as habitat indicators and play a role as key species for use in coastal ecosystem monitoring and management, emphasizing major gaps of knowledge in goatfish ecology and systematics. Currently, 66 species of goatfishes are known, the family occurring widely in tropical, subtropical and temperate habitats from the upper littoral down to the upper slope. Studies of goatfish occurrence and abundance in natural habitats have documented general preferences for sand-associated bottoms after post-larval settlement that goes hand in hand with the development of the characteristic barbels. Species, populations and later life-history stages may, however, differ significantly from each other in habitat use. Some species are more restricted to hard bottoms, others separate mainly by depth. Goatfishes respond to human-induced factors such as fisheries and habitat modification, as reflected by abundance, size, or weight changes, or changes in their distributional ranges. Temperature increase may lead to increased reproductive or growth rates and longer warming periods may induce goatfishes to migrate to higher latitudes, as exemplified by striped red mullet (Mullus surmuletus) in the North Sea. Isolated occurrences of this species in the Norwegian Sea at 60°N have been documented. Goatfishes may act as allochthonous ecosystem engineers through their vigorous foraging behaviour with barbels and mouth, which leads to the stirring-up of sediments and associated detritus particles high into the water column. Goatfishes play a key role in the formation of multi-species foraging associations as nuclear species that are followed by many other species. The role of goatfishes in food webs has been rarely evaluated and the many interactions goatfishes may be involved in have not yet been sufficiently considered. There is also a considerable lack of basic systematic and taxonomic knowledge, new species still being described and intraspecific morphological variation and genetic differentiation requiring more detailed studies. Goatfishes clearly deserve more attention in future coastal habitat exploration, monitoring and management efforts.

Adaptive responses in Cypridopsis vidua (Crustacea:Ostracoda) to food and shelter offered by a macrophyte (Chara fragilis)

The ostracod Cypridopsis vidua prefers periphyton growing on Chara fragilis to other feeding substrates. This species actively searches for periphyton, scrapes it off from Chara stems and handles it with a well organized feeding technique. When exposed to different quantities of periphyton on Chara stems, C. vidua selects foraging sites according to their nutritional value. When exposed to low quantities of water from tanks containing fish, C. vidua responds to these weak chemical cues moving from uncovered areas into Chara plants. Experiments with juvenile cyprinids (Abramis brama) as predators and C. vidua as prey clearly showed that the presence of Chara reduces fish foraging success and that C. vidua survival rate increases with increasing density of Chara.

Effects of interactions between fish populations on ecosystem dynamics in the Norwegian Sea – results of the INFERNO project

The Norwegian Sea (NS) is the feeding ground for some of the largest fish stocks in the world, including Norwegian spring spawning (NSS) herring (Clupea harengus Linnaeus, 1758; Figure 1), blue whiting (Micromesistius poutassou Risso, 1827) and the Northeast Atlantic (NA) mackerel (Scomber scombrus Linnaeus, 1758). These planktivorous stocks have substantial spatial and dietary overlap (e.g. Nøttestad et al. 1997; Dalpadado et al. 2000; Kaartvedt 2000), and are often collectively referred to as the ‘pelagic complex’ in the Norwegian Sea. Due to their high abundances, they can potentially have a strong ecological impact on the ecosystem and each other (Skjoldal et al. 2004a). The NSS herring collapsed in the late 1960’s and rebuilt during the 1980’s (Dragesund et al. 1997). Following the herring collapse, high abundances of blue whiting were discovered in the Norwegian Sea (Misund et al. 1998), and it has been speculated that the blue whiting population increased concurrently with the collapse of the NSS herring (Skjoldal et al. 1993), but the evidence remains inconclusive (Daan 1980). Since the late 1980s the abundance of fish in the NS has increased steadily and this has increased the potential for interactions between the planktivorous stocks (Figure 2). This was the background for seeking funding for the INFERNO project ‘Effects of interactions between fish populations on ecosystem dynamics and fish recruitment in the Norwegian Sea’ submitted to the Research Council of Norway (RCN) in 2005. The main hypothesis to be addressed in the INFERNO project was that the planktivorous fish populations feeding in the NS have interactions that negatively affect individual growth, mediated through depletion of their common zooplankton resource. The project was funded and lasted for the period 2006 2009 and nine papers from the INFERNO project and associated research are presented in this thematic issue of Marine Biology Research. Many of the principal investigators of the project worked at the Institute of Marine Research (IMR), but the project also benefitted strongly from interactions and exchange of data and ideas with scientists from Russia (Alexander Krysov and Vladimir Zabavnikov), the Faeroe Islands (Jan Arge Jacobsen) and Iceland (Torstein Sigurdsson and Gudmundur Óskarsson). The international partners have participated actively in the project through project meetings and as co-authors of papers. During the project period the trend of a decreasing zooplankton biomass in the NS continued and the biomass now remains low (Figure 2). The fish biomass peaked in 2004 and has since decreased somewhat, but remains fairly high. The abundance of blue whiting increased until 2004, and the range of the horizontal distribution expanded in a northwesterly direction during this period. Strong year classes of mackerel from 2001 and 2002, together with increasing temperatures, resulted in an increased number of mackerel in the Norwegian Sea (Payne et al. 2012; Utne et al. 2012a). Furthermore, there were rather substantial changes in the migration pattern of herring during the study period and thus high interannual variability in horizontal overlap between the species. There was a relatively high spatial overlap between the species during the 1990s, with a southern centre of gravity (for all three species), but due to the northern displacement of Figure 1. Herring (Clupea harengus) represents an important component of the pelagic complex of the Norwegian Sea. Photographer: David Shale (www.deepseaimages.co.uk). Marine Biology Research, 2012; 8: 415 419

Variation in locomotion behaviour in northern cutthroat eel (Synaphobranchus kaupi) on the Bay of Biscay continental slope

Based on the analysis of video sequences recorded during four dives with a manned submersible in the Bay of Biscay, NE Atlantic, evidence is provided that the northern cutthroat eel Synaphobranchus kaupi shows marked variations in abundance and in the adoption of three locomotion behaviours—forward movement, station holding, and drifting—among six ecologically different habitats. Furthermore, significant variations in association with the bottom and disturbance responses to the submersible were found. Two swimming velocity measures taken from eels during forward movement were significantly correlated with both depth and temperature. The behavioural variations observed partly occurred also between adjacent habitats that were crossed during the same dive. These results and additional observations of instantaneous fluctuations in hydrological conditions suggest that these deep-sea eels are able to adjust to ecological variability at small spatial and temporal scales in a flexible and adaptive way.

Microhabitat selection of ostracods in relation to predation and food

Experiments with the cyprinid fishVimba vimba as predator and the ostracodsCypridopsis vidua, Darwinula stevensoni andCytherissa lacustris as prey show that conspicuous coloration enhances predation risk for the ostracods. When the ostracods are allowed to retreat into sediment, risk is markedly reduced. ostracods show clear microhabitat preferences which are influenced by habitat structure and food supply. Exposed plant surfaces are visited only if they bear food and if the ostracods are not satiated.

Predation in caves: the effects of prey immobility and darkness on the foraging behaviour of two salamanders, Euproctus asper and Proteus anguinus

The behavioural responses of the blind cave salamander Proteus anguinus and the Pyrenean salamander Euproctus asper (a facultative cave dweller) to living and dead chironomids offered in light or in darkness were studied experimentally. Both species were able to detect and locate single prey items positioned at distances of 30 cm. Proteus responded to dead prey in light faster and captured live prey in darkness earlier than E. asper. E. asper captured live prey in light earlier than in darkness. Proteus is well equipped to search for non-visual information and used an active, mechanically and chemically guided approach in all experiments. E. asper showed a more directed, visually dominated approach behaviour with live chironomids in light, but used an active, widely foraging mode with live prey in darkness and dead prey in light. E. asper may forage successfully both in epigean and hypogean habitats.

Habitat, behaviour and colour patterns of orange roughy Hoplostethus atlanticus (Pisces: Trachichthyidae) in the Bay of Biscay

Analyses of 13 submersible dives on the continental slope of the Bay of Biscay (north-east Atlantic) showed that: (i) orange roughy formed dense aggregation of more than 4000 individuals per ha close to the bottom of a small underwater canyon. In all other study areas only a few individuals were observed. Orange roughy aggregations are probably associated with areas of high water mass movements and mixing; (ii) most individuals observed within this aggregation or in its peripheral areas were behaviourally inactive and could be approached with the submersible at close distance; (iii) a large number of these orange roughy showed a completely pigmentless white, or weak red coloration, never observed from specimens caught in trawls. Two individuals which were disturbed by the submarine changed from white to the ‘typical’ red coloration. These observations suggest fine tuning of the foraging strategy and life cycle of the species. It is speculated that, as an active predator of a sparse food resource, orange roughy has developed adaptations to exploit areas with specific hydrological conditions which offer high prey encounter rates and shelter during metabolic relaxation phases between foraging trips.

A new goatfish species of the genus Upeneus (Mullidae) based on molecular and morphological screening and subsequent taxonomic analysis

Abstract A new goatfish, Upeneus heemstra sp. nov. (Mullidae), from the Western Indian Ocean and SE India is described from initial DNA barcoding and quantitative morphological screening, followed by a taxonomic analysis featuring the comparison of 56 meristic, morphometric and colour characters compiled from 340 specimens of 10 phenotypically similar species. The new species differs clearly from U. oligospilus (Persian Gulf), U. tragula (Eastern Indian Ocean and West Pacific) and U. niebuhri – resurrected here – from the Gulf of Suez (Red Sea) in the combination of the following characters: caudal peduncle, head, snout, postorbital, barbel and caudal-fin length, anal-fin and second dorsal-fin height, and the number of oblique bars on the caudal fin. These four species can be distinguished from the six other species of the so-called tragula group primarily by colour pattern and appear to represent a distinct ‘dark-freckled’ species complex. An updated identification key for the tragula species group is provided and remarks on size-related and population differences are made.

Composition, distribution, and diversity of pelagic fishes around the Canary Islands, Eastern Central Atlantic

Abstract Oceanic islands of volcanic origin have a narrow shelf and a steep slope that should lead to considerable spatial overlap among coastal and oceanic fauna. During six pelagic surveys in the Canarian archipelago, Eastern Central Atlantic, over 65,000 fishes belonging to 211 species were collected at depths between 8 and 1035 m. The mesopelagic families of the lanternfishes (Myctophidae) and the bristlemouths (Gonostomatidae) accounted for about 50% of all specimens. By multivariate classification and ordination methods four different assemblages associated with mesopelagic, epipelagic–oceanic or coastal habitats could be identified. Two of these assemblages were coastal, differing in the proportion of meso- and epipelagic species. These data indicate intense horizontal migrations of mesopelagic fishes (mainly Myctophidae) into the neritic realm and increased interactions between coastal and oceanic habitats. Alpha diversity indices were higher and dominance was lower in oceanic habitats compared to the coastal realm. No marked differences among oceanographically similar areas of the entire archipelago were found. Beta diversity as a measure of similarity among sites or samples revealed variabilities between areas south of Gran Canaria and Fuerteventura islands. A considerable heterogeneity in species distribution was found off SE Fuerteventura in an area with high hydrographic variability. Therefore, both topography and hydrography are important factors influencing the distribution and abundance of pelagic fishes in this oceanic archipelago.