Autumn movements of fin whales (Balaenoptera physalus) from Svalbard, Norway, revealed by satellite tracking

Insight into animal movements is essential for understanding habitat use by individuals as well as population processes and species life-history strategies. In this study, we instrumented 25 fin whales with ARGOS satellite-transmitters in Svalbard, Norway, to study their movement patterns and behaviour (Area Restricted Search (ARS), transiting or unknown) during boreal autumn/early winter. Ten of the whales stayed in the tagging area (most northerly location: 81.68°N) for their entire tracking periods (max 45 days). The other 15 whales moved in a south-westerly direction; the longest track ended off the coast of northern Africa (> 5000 km from the tagging location) after 96 days. The whales engaged in ARS behaviour intermittently throughout their southward migrations. During transit phases the whales moved quickly; one individual maintained an average horizontal speed of 9.3 km/h (travelling 223 km per day) for a period of a week. This study documents that: (1) some fin whales might remain at high latitudes during winter; (2) the whales that do migrate probably feed along the way; (3) they can maintain high transiting speed for long periods and; (4) one breeding area for this species is likely located in deep, warm water some 100 km west of Morocco.publishedVersio

Spisateljica pomno građena kontinuiteta (Tena Štivičić, Nevidljivi (drame), Hena com, Zagreb 2015.)

<p><b>Hooded seal foraging trips during A) the post-breeding season and B) the post-molting season</b>. Blue lines represent adult males, red lines represent adult females and purple lines represent the pups. The green dot represents the mean deployment point.</p

Distribution of surface Apparent Oxygen Utilization in the biological context of the Southern Ocean in 2011.

<p>The AOU values indicate that the most oxygenated surface waters (i.e. the lowest AOU) within the PFZ and north to the SAF were related to the higher chlorophyll-a concentrations. No relation was observed in 2010.</p

Distribution of surface oxygen in the physical context of the Southern Ocean.

<p>a) In 2010, the more oxygenated waters were mainly located south to the Fawn Through Current (FTC), also called the surface expression of the Polar Front and here symbolized by the 0.5°C isotherm. b) In 2011, the surface waters North to the Subantarctic Front (SAF) were low oxygenated compared to surface waters located South to the Polar Front. Within the Polar Frontal Zone (PFZ), no clear pattern appears in the distribution of dissolved oxygen regarding to the main physical structures.</p

Relationship between Chlorophyll a Concentration, Light Attenuation and Diving Depth of the Southern Elephant Seal Mirounga leonina

Recently, a number of Antarctic marine environmental studies have used oceanographic parameters collected from instrumented top predators for ecological and physical information. Phytoplankton concentration is generally quantified through active measurement of chlorophyll fluorescence. In this study, light absorption coefficient (K-0.75) was used as an indicator of phytoplankton concentration. This measurement, easy to obtain and requiring low electric power, allows for assessing of the fine scale horizontal structuring of phytoplankton. As part of this study, Southern elephant seals (SES) were simultaneously equipped with a fluorometer and a light logger. Along the SES tracks, variations in K-0.75 were strongly correlated with chlorophyll, a concentration measured by the fluorometer within the euphotic layer. With regards to SES foraging behaviour, bottom depth of the seal's dive was highly dependent on light intensity at 150 m, indicating that the vertical distribution of SES's prey such as myctophids is tightly related to light level. Therefore, change in phytoplankton concentration may not only have a direct effect on SES's prey abundance but may also determine their vertical accessibility with likely consequences on SES foraging efficiency

Difference in dissolved oxygen concentration along the seal tracks regarding the position of the main oceanic fronts a) in 2010 b) in 2011.

<p>The fronts were defined by the sea surface temperature and the literature.</p

Relationship between the AOU values along the seal tracks and the mean concentration of Chl-a extracted under each location recorded in 2011.

<p>The higher the concentration in Chl-a, the lower the values of AOU. The black line represents the significant linear regression: <i>y</i> = −6.4<i>x</i> + 23.7, p < 0.001.</p