Establishing species–habitat associations for 4 eteline snappers with the use of a baited stereo-video camera system

With the use of a baited stereo-video camera system, this study semiquantitatively defined the habitat associations of 4 species of Lutjanidae: Opakapaka (Pristipomoides filamentosus), Kalekale (P. sieboldii), Onaga (Etelis coruscans), and Ehu (E. carbunculus). Fish abundance and length data from 6 locations in the main Hawaiian Islands were evaluated for species-specific and size-specific differences between regions and habitat types. Multibeam bathymetry and backscatter were used to classify habitats into 4 types on the basis of substrate (hard or soft) and slope (high or low). Depth was a major influence on bottomfish distributions. Opakapaka occurred at depths shallower than the depths at which other species were observed, and this species showed an ontogenetic shift to deeper water with increasing size. Opakapaka and Ehu had an overall preference for hard substrate with low slope (hard-low), and Onaga was found over both hard-low and hard-high habitats. No significant habitat preferences were recorded for Kalekale. Opakapaka, Kalekale, and Onaga exhibited size-related shifts with habitat type. A move into hard-high environments with increasing size was evident for Opakapaka and Kalekale. Onaga was seen predominantly in hard-low habitats at smaller sizes and in either hard-low or hard-high at larger sizes. These ontogenetic habitat shifts could be driven by reproductive triggers because they roughly coincided with the length at sexual maturity of each species. However, further studies are required to determine causality. No ontogenetic shifts were seen for Ehu, but only a limited number of juveniles were observed. Regional variations in abundance and length were also found and could be related to fishing pressure or large-scale habitat features

Phylogeographic Analyses of Submesophotic Snappers Etelis coruscans and Etelis “marshi” (Family Lutjanidae) Reveal Concordant Genetic Structure across the Hawaiian Archipelago

The Hawaiian Archipelago has become a natural laboratory for understanding genetic connectivity in marine organisms as a result of the large number of population genetics studies that have been conducted across this island chain for a wide taxonomic range of organisms. However, population genetic studies have been conducted for only two species occurring in the mesophotic or submesophotic zones (30+m) in this archipelago. To gain a greater understanding of genetic connectivity in these deepwater habitats, we investigated the genetic structure of two submesophotic fish species (occurring ∼200–360 m) in this archipelago. We surveyed 16 locations across the archipelago for submesophotic snappers Etelis coruscans (N = 787) and E. “marshi” (formerly E. carbunculus; N = 770) with 436–490 bp of mtDNA cytochrome b and 10–11 microsatellite loci. Phylogeographic analyses reveal no geographic structuring of mtDNA lineages and recent coalescence times that are typical of shallow reef fauna. Population genetic analyses reveal no overall structure across most of the archipelago, a pattern also typical of dispersive shallow fishes. However some sites in the mid-archipelago (Raita Bank to French Frigate Shoals) had significant population differentiation. This pattern of no structure between ends of the Hawaiian range, and significant structure in the middle, was previously observed in a submesophotic snapper (Pristipomoides filamentosus) and a submesophotic grouper (Hyporthodus quernus). Three of these four species also have elevated genetic diversity in the mid-archipelago. Biophysical larval dispersal models from previous studies indicate that this elevated diversity may result from larval supplement from Johnston Atoll, ∼800 km southwest of Hawaii. In this case the boundaries of stocks for fishery management cannot be defined simply in terms of geography, and fishery management in Hawaii may need to incorporate external larval supply into management plans

Bayesian clustering analysis results obtained with the program STRUCTURE 2.3.3 (Pritchard 2000) using sample location as a prior for (a) <i>Etelis coruscans</i>, <i>K</i> = 2 and (b) <i>Etelis marshi</i>, <i>K</i> = 3.

<p>Bayesian clustering analysis results obtained with the program STRUCTURE 2.3.3 (Pritchard 2000) using sample location as a prior for (a) <i>Etelis coruscans</i>, <i>K</i> = 2 and (b) <i>Etelis marshi</i>, <i>K</i> = 3.</p

Characteristics of 16 microsatellite loci developed for <i>Etelis coruscans</i> and <i>Etelis marshi</i>, including number of alleles (<i>k</i>), observed heterozygosity (<i>H_o</i>), and expected heterozygosity (<i>H_e</i>) across the Hawaiian Archipelago for each locus.

<p>Characteristics of 16 microsatellite loci developed for <i>Etelis coruscans</i> and <i>Etelis marshi</i>, including number of alleles (<i>k</i>), observed heterozygosity (<i>H_o</i>), and expected heterozygosity (<i>H_e</i>) across the Hawaiian Archipelago for each locus.</p

Correlation between genetic distance (pairwise <i>Φ</i>_ST or <i>F</i>_ST) and geographic distance between sample sites for (a) mtDNA cytochrome <i>b</i> (<i>P</i> = 0.044, <i>r</i> = 0.126) and (b) microsatellites (<i>P</i> = 0.042, <i>r</i> = 0.171) for <i>Etelis coruscans</i>.

<p>Correlations between genetic and geographic distance were non-significant for both marker types for <i>Etelis marshi</i>.</p

Map of the Hawaiian Archipelago and Johnston Atoll showing sampling locations and geographic division between the Northwestern Hawaiian Islands and the Main Hawaiian Islands.

<p>Map of the Hawaiian Archipelago and Johnston Atoll showing sampling locations and geographic division between the Northwestern Hawaiian Islands and the Main Hawaiian Islands.</p

Tajima's <i>D</i> values, Fu's <i>F</i>_S values, and mismatch distribution parameter estimates calculated using mtDNA cyt<i>b</i> sequences for <i>Etelis marshi</i>. <i>t</i>: coalescent time; ⊖₀ (<i>N</i>_{f<i>t = 0</i>}): initial female effective population size; ⊖₁(<i>N</i>_{f<i>t = 1</i>}): post-expansion female effective population size.

<p>Some estimates of ⊖₁ yielded the maximum allowable value (99,999, here indicated by ∞), so that the calculation of <i>N_ft = 1</i> was not possible (NA).</p><p>*<i>P</i><0.05.</p

Sample sizes, diversity indices, and sampling years for mtDNA cytochrome b (cyt<i>b</i>) and microsatellite loci across sample sites in the Hawaiian Archipelago for <i>Etelis marshi</i>. <i>h</i>, haplotype diversity; π, nucleotide diversity; <i>A</i>_R allele richness; <i>H_o</i>, observed heterozygosity; <i>H_e</i>, expected heterozygosity.

<p>For geographic locations with sampling intervals >1 year apart, the number of specimens sampled per interval is given in parentheses.</p

Median-joining network of cytochrome <i>b</i> haplotypes for (a) <i>Etelis coruscans</i> and (b) <i>Etelis marshi</i> obtained from the program NETWORK 4.6.1.0 (Bandelt <i>et al.</i> 1999).

<p>Each circle represents a haplotype; circle sizes are proportional to the frequency of haplotypes; and line lengths are proportional to the number of mutational steps between haplotype sequences.</p