Predicting early life connectivity of Antarctic silverfish, an important forage species along the Antarctic Peninsula

Abstract

The early life stages of the Antarctic silverfish (Pleuragramma antarctica), an important prey species for higher predators in the Southern Ocean ecosystem, dominate the larval fish assemblages of the Bransfield Strait, one of the most important areas for larval retention off the Antarctic Peninsula. Nevertheless, the spatial location of areas where they were spawned and the timing of larval hatching remain unknown. By linking Lagrangian particle tracking simulations with age data obtained using otolith microincrements from fish caught north of Joinville Island in a pelagic survey, we estimated the distribution of hatch dates and subsequent growth rates of silverfish reaching the Bransfield Strait, and predicted the areas where they were spawned. Larval hatching peaked during the last week of December, and the inner shelf and shelf break, east of the Larsen Ice shelf, were the dominant areas predicted to contribute to larval assemblages in the Bransfield Strait. Over simulated periods of 600–630 days, 35–40% of particles remained within the Bransfield Strait, suggesting an important source of supply to higher predators feeding off the northern Antarctic Peninsula. The daily growth rate at the mean size of 22.3 mm was 0.18 mm, corresponding to a daily change in size of approximately 0.82% standard length (SL), and large variability in growth rate suggested a wide range of environmental conditions experienced during the period of advection from the spawning areas. These results provide spatial predictions that can be tested empirically in future studies, using the simulated trajectories to inform sampling design and spatial coverage.

Assemblages of micronektonic fishes and invertebrates in a gradient of regional warming along the Western Antarctic Peninsula

“…Year-class strengths have been variable (Kellermann, 1996), but a steady larval supply has been present whenever sampling has taken place. Recent modeling of larval transport for Pleuragramma originating in the Weddell Sea strongly corroborates the dispersal path described above, both in terms of trajectory and timing relative to hatch-date (La Mesa et al, 2015). Once in the Bransfield Strait, larvae could be transported south via the Antarctic Peninsula Coastal Current (APCC), potentially to the Palmer Archipelago, the Biscoe Islands, and Marguerite Bay (Moffat et al, 2008;Niiler et al, 1991).…”

“…Kellermann, 1996;La Mesa and Eastman, 2012;La Mesa et al, 2015) is that recruitment of Pleuragramma to the waters of the WAP shelf is by larval dispersal, a "larval pump", from spawning centers located in the western Weddell Sea (e.g. Larsen Bay) and the continental Bellingshausen Sea southwest of the Peninsula (Kellermann and Schadwinkel, 1991).…”

“…Larvae are assumed to be transported from the Weddell Sea via the Weddell Gyre/Antarctic Coastal Current as it flows through the Antarctic Sound and bends around Joinville Island ( Fig. 1; Stein, 1983;Hofmann et al, 1996;La Mesa et al, 2015) and into the eastern Bransfield Strait. Larvae originating in the other hypothetical spawning site, the continental Bellingshausen Sea south of the peninsula, would be transported northeast in the upper 100 m of the Antarctic Circumpolar Current (ACC), merging with the general northeasterly flow at the shelf break along the peninsula, and making their way further inshore via the cross-shelf gyral flows in the vicinity of Alexander Island, Renaud Island, and the southern Bransfield Strait ( Fig.…”

“…The "larval pump" hypothesis is supported by a consistent presence of larval Pleuragramma antarctica in the Bransfield Strait from the 1970's through the 1990's (Kellermann, 1986(Kellermann, , 1996Loeb, 1991;Morales-Nin et al, 1998) up through at least 2011 (La Mesa et al, 2015). Year-class strengths have been variable (Kellermann, 1996), but a steady larval supply has been present whenever sampling has taken place.…”

Impact of hatch date on early life growth and survival of Mueller’s pearlside (Maurolicus muelleri) larvae and life-history consequences

“…The coupling of larval drift simulations and otolith-based individual larval growth trajectories has successfully been employed in a wide range of species and ecosystems, increasing our understanding of seasonal larval growth and survival dynamics (e.g., Itoh et al 2011;La Mesa et al 2015;Mountain et al 2008). However, this study represents one of the few studies in northeastern Atlantic waters where larval growth trajectories are coupled with high-resolution simulated drift patterns to partition major sources of mortality (but see Gallego et al 1996;Allain et al 2003;Hinrichsen et al 2010).…”