Larval Trophodynamics, Turbulence, and Drift on Georges Bank : A Sensitivity Analysis of Cod and Haddock

Using an individual-based model approach we consider trophodynamic effects on the growth and survival of larval cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) on Georges Bank during late winter/early spring. These studies represent an extension of results described in Werner et al. (1996; Deep-Sea Res. II), wherein the effect of turbulence-enhanced larval-prey contact rates increased the effective prey concentration resulting in growth of cod larvae consistent with observed rates in the field. We reformulated the feeding of the larvae to include existing relationships between maximum prey-length and larval-length and we examined: (i) larval search behaviour and its effect on encounter with prey, (ii) the ability of larvae to pursue and capture prey in a turbulent environment, and (iii) the effect of turbulence on the dispersion of larvae in the vertical. We find that search behaviour, the effect of turbulence on pursuit and capture, and vertical dispersion decrease the predicted larval growth rates compared to those observed in the earlier study. These results suggest that larval feeding behaviour, and especially the ability of larvae to pursue encountered prey, could be an important input to larval growth and survival models. The inclusion of turbulence in determining the position of passive larvae in the water column allows the larvae to sample the entire water column, contributing to a decrease in the variance of the size of the larvae over time. The ability of larvae to swim and aggregate in the vertical will be necessary to reproduce distributions observed in the field

The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny.

The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra), two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa). In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha, Caenogastropoda, and Heterobranchia) were all monophyletic, and thus appear to be better classifications for this diverse group

EFFECT OF OPEN BOUNDARY CONDITIONS ON THE TIDAL MODELING AROUND THE WEST COAST OF KOREA

The aim of this study is to investigate the effect of open boundary conditions on the tidal elevation from major tidal constituents around the West Coast of Korea (WCK). To obtain a detailed tidal forcing at open boundaries, three well-known assimilated tidal models; NAO.99b, FES2014 and NAO.99Jb, have been applied to interpolate the offshore tidal boundary conditions. Before applying the results obtained from these tidal models, they have been validated against the observation data. The numerical simulations are based on two different open source numerical models; the Finite Volume Coastal Ocean Model (FVCOM) and TELEMAC. In order to find out the dependence of the tidal elevation around the WCK on the variations of open boundary forcing, a sensitivity analysis of coastal tide elevation was carried out. Consequently, it shows that the tidal elevation around the WCK has different local responses to the offshore tides at the open boundaries; and the numerical results can provide better tidal information around the WCK than the assimilated tidal models.N

Cytochrome oxidase 1 sequence differences in <i>Melibe</i> genus.

<p>Nucleotide (A) and amino acid (B) alignments of a portion of the cytochrome oxidase 1 gene for <i>M</i>. <i>leonina</i> and other members of the <i>Melibe</i> genus indicate that <i>M</i>. <i>leonina</i> lacks the twelve nucleotide deletion present in other species.</p

Gastropod mitochondrial genomes used in this study.

<p>(*) indicates a classification that was not supported by this study.</p><p>Gastropod mitochondrial genomes used in this study.</p

Maximum likelihood analysis of gastropod phylogeny, based on amino acid alignment of 72 gastropods.

<p>Bootstrap support values indicate the confidence of each node. The bivalve, <i>Venustaconcha ellipsiformis</i>, was used an outgroup. Colors as in Fig 6. While there are minor differences compared to the Bayesian analysis (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127519#pone.0127519.g005" target="_blank">Fig 5</a>), the topology of major groups is the same (see consensus in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127519#pone.0127519.g007" target="_blank">Fig 7</a>).</p

Opisthobranch phylogeny based on nucleotide sequences of the thirteen protein-coding genes of the mitochondrial genome.

<p>Both Bayesian and maximum likelihood analyses resulted in identical topologies, shown here as a consensus tree with branch lengths depicted from the maximum likelihood analysis. All sampled orders were found to be monophyletic groups. Numbers at nodes indicate posterior probabilities (Bayesian) followed by bootstrap values (maximum likelihood), indicating statistical confidence in that particular node.</p

Bayesian analysis of gastropod phylogeny, based on amino acid alignment of 72 gastropods.

<p>Posterior probability values indicate the confidence of each node. The bivalve, <i>Venustaconcha ellipsiformis</i>, was used an outgroup. The traditional subclasses are highlighted (pulmonates in red, opisthobranchs in green, and prosobranchs in blue). Two of the three traditional subclasses (pulmonates and opisthobranchs) were not monophyletic. In contrast, the four more recently distinguished gastropod groups (Heterobranchia, Caenogastropoda, Vetigastropoda, and Neritimorpha) were all monophyletic.</p

The complete mitochondrial genomes of <i>Melibe leonina</i> (A) and <i>Tritonia diomedea</i> (B).

<p>Both mitochondrial genomes were found to code for the expected 22 transfer RNA, 13 protein-coding genes, and a short and large ribosomal subunit. The 13 protein-coding gene order was found to be identical to all other opisthobranchs.</p