Utilizing individual fish biomass and relative abundance models to map environmental niche associations of adult and juvenile targeted fishes

Many fishes undergo ontogenetic habitat shifts to meet their energy and resource needs as they grow. Habitat resource partitioning and patterns of habitat connectivity between conspecific fishes at different life-history stages is a significant knowledge gap. Species distribution models were used to examine patterns in the relative abundance, individual biomass estimates and environmental niche associations of different life stages of three iconic West Australian fishes. Continuous predictive maps describing the spatial distribution of abundance and individual biomass of the study species were created as well predictive hotspot maps that identify possible areas for aggregation of individuals of similar life stages of multiple species (i.e. spawning grounds, fisheries refugia or nursery areas). The models and maps indicate that processes driving the abundance patterns could be different from the body size associated demographic processes throughout an individual's life cycle. Incorporating life-history in the spatially explicit management plans can ensure that critical habitat of the vulnerable stages (e.g. juvenile fish, spawning stock) is included within proposed protected areas and can enhance connectivity between various functional areas (e.g. nursery areas and adult populations) which, in turn, can improve the abundance of targeted species as well as other fish species relying on healthy ecosystem functioning

Supporting Online Material (SOM) for: Impact of contrasting conditions at the North-Western Azores Current on carbon-and N 2fixation rates and the abundance of diazotrophic unicellular cyanobacteria

Supplementary data for Riou et al. 2016 PLos On

Importance of N2-Fixation on the Productivity at the North-Western Azores Current/Front System, and the Abundance of Diazotrophic Unicellular Cyanobacteria

International audienceTo understand the impact of the northwestern Azores Current Front (NW-AzC/AzF) system on HCO 3 −-and N 2-fixation activities and unicellular diazotrophic cyanobacteria (UCYN) distribution , we combined geochemical and biological approaches from the oligotrophic surface to upper mesopelagic waters. N 2-fixation was observed to sustain 45-85% of the HCO 3 −-fix-ation in the picoplanktonic fraction performing 47% of the total C-fixation at the deep chlorophyll maximum north and south of the AzF. N 2-fixation rates as high as 10.9 μmol N m-3 d-1 and surface nitrate δ 15 N as low as 2.7‰ were found in the warm (18-24°C), most saline (36.5-37.0) and least productive waters south of the AzF, where UCYN were the least abundant. However, picoplanktonic UCYN abundances up to 55 cells mL-1 were found at 45-200m depths in the coolest nutrient-rich waters north of the AzF. In this area, N 2-fixation rates up to 4.5 μmol N m-3 d-1 were detected, associated with depth-integrated H 13 CO 3 −-fixa-tion rates at least 50% higher than observed south of the AzF. The numerous eddies generated at the NW-AzC/AzF seem to enhance exchanges of plankton between water masses, as well as vertical and horizontal diapycnal diffusion of nutrients, whose increase probably enhances the growth of diazotrophs and the productivity of C-fixers

Sea Surface Height and geostrophic currents during the DIAPICNA cruise.

<p>Station locations (open circles) overlaid on AVISO altimetry-derived geostrophic currents centered between 26/07/2011 and 01/08/2011, with color scale indicating the Sea Surface Height (SSH) in m.</p

Physical parameters monitored along the DIAPICNA cruise track.

<p>(A) Temperature (°C) longitudinal cross-section, with the position of the Azores Front deduced from the 16°C isotherm at 200m depth (dotted lines); (B) TS diagrams for stations A-E, with overlaid σ_θ density isolines. NACW: North Atlantic Central Water; 15MW: 15°C Mode Water; 18MW: 18°C Mode Water; SAIW: SubArctic Intermediate Water; MedW: Mediterranean Water; LSW: Labrador Sea Water. The black box indicates possible increased influence of Mediterranean Waters at 800–1000m in stations D and E.</p

Distribution of Carbon fixation and Organic Carbon in <3 μm and >3 μm large particles.

<p>(A) C-fixation rates (μmol m^-3 d^-1), and (B) longitudinal cross-sections of POC (μmol L^-1) depending on the particle size fraction (left: <3 μm; right: >3 μm). The Azores Front position is marked by a bold line.</p

Significant correlations between C-, N₂-fixations, UCYN abundance and physical-chemical conditions.

<p>Significant correlations between C-, N₂-fixations, UCYN abundance and physical-chemical conditions.</p

Geochemical tracers of N₂-fixation along the DIAPICNA cruise transect.

<p>Longitudinal cross-sections of (A) nitrate concentration, (B) δ¹⁵N_NO3 signal, (C) PN isotopic signature and (D) Δ(15,18)—see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150827#pone.0150827.e002" target="_blank">eq (2)</a>. The position of the Azores Front is indicated by a dashed line, and station i.d. is given on top.</p