Search

Pelagic egg surveys are commonly used to map Atlantic cod spawning areas in the northeastern Atlantic. However, a sampling location may not necessarily indicate a spawning location, because more developed eggs may have drifted long distances in coastal currents. Newly spawned eggs have only a few embryonic cells, whereas eggs in later developmental stages have progressively larger numbers of cells and hence greater amounts of DNA. The progression through developmental stages largely depends on temperature, which influences cell division and growth. Preservation of the eggs for later analysis presents logistical dilemmas. Preservation in ethanol is suitable for DNA extraction but obscures developmental stage, as the eggs shrink and turn opaque. On the other hand, preservation in formaldehyde retains visual characteristics, but this method limits the ability to extract intact DNA. Here we report a method to estimate developmental stages in Atlantic cod eggs by assaying the amount of DNA from eggs preserved in ethanol. We used a correlation between the amount of DNA in an egg and its embryonic developmental stage in samples from western Norway and used this correlation to estimate developmental stages of eggs sampled in northern Norway.

Population structuring in the northern shrimp (Pandalus borealis) in the North Sea area (including Fladen and Skagerrak) was studied by microsatellite DNA analyses. Screening 20 sample locations in the open ocean and Skagerrak fjords for nine loci revealed low, but significant genetic heterogeneity. The spatial genetic structure among oceanic samples of Skagerrak and the eastern North Sea was weak and non-significant, consistent with the current management regime of one single stock. However, Skagerrak fjord samples generally displayed elevated levels of genetic differentiation, and significantly so in several pairwise comparisons with other fjords and oceanic samples. Although the Skagerrak fjord populations are of less economic value, some of them are regulated separately (e.g. the Gullmarsfjord) and local stocks may prove important to uphold genetic variability and biocomplexity in a changing environment.

Catarino, Diana ... et. al.-- 19 pages, 5 figures, 4 tables, data accessibility http://dx.doi.org/10.5061/dryad.ss368, supporting information http://dx.doi.org/10.1111/mec.13453, Knowledge of the mechanisms limiting connectivity and gene flow in deep-sea ecosystems is scarce, especially for deep-sea sharks. The Portuguese dogfish (Centroscymnus coelolepis) is a globally distributed and near threatened deep-sea shark. C. coelolepis population structure was studied using 11 nuclear microsatellite markers and a 497-bp fragment from the mtDNA control region. High levels of genetic homogeneity across the Atlantic (Φ = -0.0091, F = 0.0024, P > 0.05) were found suggesting one large population unit at this basin. The low levels of genetic divergence between Atlantic and Australia (Φ = 0.0744, P < 0.01; F = 0.0015, P > 0.05) further suggested that this species may be able to maintain some degree of genetic connectivity even across ocean basins. In contrast, sharks from the Mediterranean Sea exhibited marked genetic differentiation from all other localities studied (Φ = 0.3808, F = 0.1149, P < 0.001). This finding suggests that the shallow depth of the Strait of Gibraltar acts as a barrier to dispersal and that isolation and genetic drift may have had an important role shaping the Mediterranean shark population over time. Analyses of life history traits allowed the direct comparison among regions providing a complete characterization of this shark's populations. Sharks from the Mediterranean had markedly smaller adult body size and size at maturity compared to Atlantic and Pacific individuals. Together, these results suggest the existence of an isolated and unique population of C. coelolepis inhabiting the Mediterranean that most likely became separated from the Atlantic in the late Pleistocene, This study was performed under the framework of ReDEco (FP6 ERA-NET, MARIN-ERA/MAR/0003/2008) and Hermione (FP7-ENV-2008-1, nr 226354) projects. Samples were collected under other scientific projects: DEECON (ESF, 06-EuroDEEP-FP-008 & SFRH-EuroDEEP/0002/2007); CONDOR (EEA Grants, PT0040/2008); SMaRT (M.2.1.2/029/2011) and DEMERSAIS (Azorean Government); OASIS (FP5, EVK3-CT-2002-00073-OASIS); PescProf I (INTERREG III B, MAC/4.2/M12); BIOFUN (ESF, CTM2007-28739-E); DOS MARES (CTM2010-21810-C03-03); ADIOS (EVK3-CT-2000-00035). DC is a PhD student funded by FCT (SFRH/BD/65730/2009); HK is cofunded by the University of Agder and the University of Oslo (CEES); AV is a postdoctoral fellow funded by FCT (POPH/FSE; SFRH/BPD/77487/2011); DS is a postdoctoral fellow funded by the DIANET programme (FP1527385002); and SS is a research fellow supported by the Marie Curie grant cofunded by the EU under the FP7-People-2012-COFUND; Cofunding of Regional, National and International Programmes, GA n.600407 and the Bandiera Project RITMARE. MARE is funded by FCT through the strategic project UID/MAR/04292/2013

Microsatellites represent an important tool for characterising population structure, for attributing individuals to stocks, and for revealing ecological processes taking place on population and meta-population levels. A sound knowledge of population structure is essential for sustainable management of exploited fish stocks, and helps to understand population connectivity and speciation. We developed for the first time primers for microsatellite loci in the carapine grenadier, Coryphaenoides carapinus, inhabiting the abyssal Atlantic. Eleven microsatellites were obtained from partial genomic DNA libraries enriched for tetranucleotide repeats. The loci were characterised in three unrelated individuals and nine loci were found to be polymorphic. Cross-amplification in two commercially exploited deep-sea macrourid species (Coryphaenoides rupestris and Macrourus berglax) resolved two polymorphic loci in each species.

We developed polymerase chain reaction primers for nine dinucleotide microsatellite loci in the marine deep-sea fish, the tusk (Brosme brosme). All markers were obtained from a partial genomic DNA library, and characterized in 100 unrelated individuals from one putative population. The number of alleles ranged from two to 60 with an average of 15/locus. The observed heterozygosity ranged from 0.020 to 0.826 (average 0.438). Several of the markers amplified multiple alleles from the two other gadoid species tested.

Journal homepage: http://www.springerlink.com/content/1877-7252/ We developed 12 microsatellite loci primers in 8 the corkwing wrasse (Symphodus melops). All markers 9 were obtained from partial genomic DNA libraries enri-10 ched for tetranucleotide repeats and characterized in 32 11 unrelated individuals from one putative population. The 12 number of alleles ranged from 5 to 18, with an average of 13 8.6 per locus, and the observed heterozygosity ranged from 14 0.464 to 0.969 (average 0.697). Cross-amplification in two 15 closely related commercially exploited species, the ballian 16 wrasse (Labrus bergylta) and the goldsinny wrasse (Cten- 17 olabrus rupestris), successfully resolved four loci of which 18 two were polymorphic and two where monomorphic.

Population structuring in the North Atlantic deepwater demersal fish tusk (Brosme brosme) was studied with microsatellite DNA analyses. Screening eight samples from across the range of the species for seven loci revealed low but significant genetic heterogeneity (F(ST) = 0.0014). Spatial genetic variability was only weakly related to geographical (Euclidean) distance between study sites or separation of study sites along the path of major ocean currents. Instead, we found a significant effect of habitat, indicated by significant differentiation between relatively closely spaced sites: Rockall, which is surrounded by very deep water (1000 m), and the Mid-Atlantic Ridge, which is separated from the European slope by a deep ocean basin, were differentiated from relatively homogeneous sites across the Nordic Seas. Limited adult migration across bathymetric barriers in combination with limited intersite exchange of pelagic eggs and larvae due to site-specific circulatory retention or poor survival during drift phases across deep basins may be reducing gene flow. We regard these limitations to gene flow as the most likely mechanisms for the observed population structure in this demersal species. The results underscore the importance of habitat boundaries in marine species.

We developed 11 microsatellite loci primers in the bathypelagic black scabbardfish (Aphanopus carbo), a novelty for deep-sea fishes. All markers were obtained from partial genomic DNA libraries enriched for tetranucleotide repeats and characterized in 50 unrelated individuals from one putative population. The number of alleles ranged from 5 to 40, with an average of 19.3 per locus, and the observed heterozygosity ranged from 0.387 to 0.961 (average 0.749). Cross-amplification in another closely related commercially exploited deep-sea species intermediate scabbardfish (Aphanopus intermedius) resolved 11 polymorphic loci.