Vertical zonation and functional diversity of fish assemblages revealed by ROV videos at oil platforms in The Gulf.

An assessment of vertical distribution, diel migration, taxonomic and functional diversity of fishes was carried out at offshore platforms in The (Arabian-Iranian-Persian) Gulf. Video footage was recorded at the Al Shaheen oil field between 2007 and 2014 using a remotely operated vehicle (ROV). A total of 12 822 individual fishes, from 83 taxonomic groups were recorded around the platforms. All the species identified are considered native to The Gulf, although Cyclichthys orbicularis and Lutjanus indicus were recorded for the first time in Qatari waters. Several trends were uncovered in the vertical distribution of the fish community; most species were observed between 20 and 50 m depth and fish abundance decreased towards the bottom, with the highest abundances recorded in the upper layers, i.e. down to 40 m depth. Vertical variation in fish diversity, however, was generally not accompanied by differences in vertical movements. Carnivores and invertivores were the dominant trophic groups, being found at each depth range from surface to seabed. The functional indices showed no significant differences between water depths or diel cycles. The study demonstrates that oil platforms represent a hotspot of fish diversity and interesting sites for studying fish communities, abundance and behaviour.

Exploring the diversity of Arctic eelpouts: first cytogenetic data on species of the genus Lycodes (Teleostei, Zoarcidae).

Zoarcidae (eelpouts), including 298 recognized valid species, is the most diverse family in the suborder Zoarcoidei (order Perciformes). Many of the species exhibit a great degree of phenotypic plasticity. In the present work, we analyze the genome of six Arctic species from the most diversified zoarcid genus Lycodes (L. eudipleurostictus, L. paamiuti, L. pallidus, L. seminudus, L. squamiventer, and L. reticulatus) providing the first information on the species-specific karyotype and pattern of major ribosomal genes chromosomal localization. The study revealed an unexpected consistency of the chromosomal features across species that apparently contrasts with the high level of inter-specific and intra-specific plasticity of morphological characters. The comparison between the chromosomal features of these Arctic eelpouts with those of the Antarctic species Lycodichthys dearborni (same subfamily, Lycodinae), suggests a conservative organization of the genome, at the level of gross architecture of chromosomes and karyotypes, within the family Zoarcidae.

Revision of the bathyal cusk-eels of the genus Bassogigas (Ophidiidae) with description of a new species from off Guam, west Pacific Ocean.

The bathyal genus Bassogigas (Teleostei: Ophidiidae) is revised based on 25 specimens, 18 from the west Atlantic Ocean and seven from the Indo-west Pacific Ocean. One specimen, from off Guam, west Pacific Ocean, represents a new species, Walker's cusk eel Bassogigas walkeri. The other 24 specimens all belong to the type species, Gills cusk eel Bassogigas gillii. A comparison between the Atlantic and the Indo-west Pacific Ocean specimens of B. gillii showed no differences in meristic and morphometric characters, but in two of the Indo-west Pacific Ocean specimens the sagittal otolith varied somewhat from the remaining specimens. The two Bassogigas species differ in the length of the lateral line, the number of scales in the midline of the body, the form of the median basibranchial tooth patches and in the thickness of the otolith.

Phylogeny of the snailfishes (Teleostei: Liparidae) based on molecular and morphological data.

Liparidae (snailfishes) is one of the most diverse and abundant fish families in polar and deep-sea habitats. However, the evolution of this family is poorly known because of the rarity of many species and difficulties in scoring morphological characters. We perform phylogenetic analyses of Liparidae using sequences from two mtDNA genes, 16S (585 bp) and cytochrome b (426 bp), and 84 morphological characters from 24 species of Liparidae and 4 species of Cyclopteridae (outgroup). The present study confirms earlier hypotheses that the shallow-water genera, such as Liparis and Crystallichthys, occupy basal positions and that deep-water genera, such as Careproctus, Elassodiscus, Rhinoliparis, Paraliparis, Rhodichthys and Psednos, are increasingly derived. The later two genera form a terminal clade which does not include Paraliparis. The topology shows that the family has undergone a reductive type of evolution, with a gradual loss of characters (e.g. sucking disc/pelvic fins, pseudobranchial filaments, skin spinules). Nectoliparis, which had previously been placed either as the basal most genus or among the most derived genera, are found to occupy the most basal position among the taxa analyzed. This result indicates that the sucking disc has been lost at least twice during the evolution of the Liparidae. The basal position of Nectoliparis is supported by its plesiomorphic otolith morphology, whereas an advanced overgrown otolith ostium, unique among teleosts, is found to be apomorphic for a clade containing the derived genera: Paraliparis, Psednos, Rhinoliparis and Rhodichthys. We also identify the presence of probable nuclear inserts of mitochondrial DNA (Numts) in three species of Careproctus and in Elassodiscus caudatus.