Long-term (1993–2013) changes in macrozooplankton off the Western Antarctic Peninsula

Steinberg, Deborah K.; Ruck, Kate E.; Gleiber, Miram R.; Garzio, Lori; Cope, Joseph S.; Bernard, Kim S.; Stammerjohn, Sharon; Schofield, Oscar; Quetin, Langdon B.; Ross, Robin M.

doi:10.1016/j.dsr.2015.02.009

Cited by 153 publications

(199 citation statements)

References 76 publications

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“…The Western Antarctic Peninsula (WAP) is one of the most rapidly warming areas on Earth41, and krill is the most abundant species in the coastal areas of this region23; predators such as fish, seabirds, penguins, seals and whales rely on this single resource. The presence of numerous krill-feeding whales in fjords, such as Potter Cove and others along the WAP, as well as the presence of the dominant benthic fish species Notothenia coriiceps , which feeds primarily on krill20, underscore the importance of krill for these regions.…”

Section: Discussionmentioning

confidence: 99%

Glacial melting: an overlooked threat to Antarctic krill

Fuentes

Alurralde

Meyer

et al. 2016

Sci Rep

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Strandings of marine animals are relatively common in marine systems. However, the underlying mechanisms are poorly understood. We observed mass strandings of krill in Antarctica that appeared to be linked to the presence of glacial meltwater. Climate-induced glacial meltwater leads to an increased occurrence of suspended particles in the sea, which is known to affect the physiology of aquatic organisms. Here, we study the effect of suspended inorganic particles on krill in relation to krill mortality events observed in Potter Cove, Antarctica, between 2003 and 2012. The experimental results showed that large quantities of lithogenic particles affected krill feeding, absorption capacity and performance after only 24 h of exposure. Negative effects were related to both the threshold concentrations and the size of the suspended particles. Analysis of the stomach contents of stranded krill showed large quantities of large particles ( > 106 μm3), which were most likely mobilized by glacial meltwater. Ongoing climate-induced glacial melting may impact the coastal ecosystems of Antarctica that rely on krill.

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Section: Discussionmentioning

confidence: 99%

Glacial melting: an overlooked threat to Antarctic krill

Fuentes

Alurralde

Meyer

et al. 2016

Sci Rep

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“…Larger krill may find maintaining position against a current to be less of a metabolic burden than age 1+ krill, and may choose to stay in an area with fewer predators than the coastal fjords. The observed abundance of age 1+ krill could also be related to multiyear patterns in krill recruitment, as 2013 was a particularly high recruitment year for krill in the WAP region (Steinberg et al 2015), although the lack of a strong age 2+ year class within the fjords suggests recruitment variability is not the full explanation for the observed length distributions as 2012 was also a strong krill recruitment year (Steinberg et al 2015).…”

Section: Minimizing Advective Lossesmentioning

confidence: 99%

Winter distribution and size structure of Antarctic krill Euphausia superba populations in-shore along the West Antarctic Peninsula

Cleary¹,

Durbin²,

Casas³

et al. 2016

Mar. Ecol. Prog. Ser.

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Antarctic krill Euphausia superba are a key component of food webs in the maritime West Antarctic Peninsula, and their life history is tied to the seasonal cycles of sea ice and primary production in the region. Previous work has shown a general in-shore migration of krill in winter in this region; however, the very near-shore has not often been sampled as part of these surveys. We investigated distribution, abundance, and size structure of krill in 3 fjordic bays along the peninsula, and in the adjacent Gerlache Strait area using vertically stratified MOCNESS net tows and ADCP acoustic biomass estimates. Krill abundance was high within bays, with net estimated densities exceeding 60 krill m −3 , while acoustic estimates were an order of magnitude higher. Krill within bays were larger than krill in the Gerlache Strait. Within bays, krill aggregations were observed near the seafloor during the day with aggregations extending to the sediment interface, and exhibited diel vertical migration higher into the water column at night. We suggest these high winter krill abundances within fjords are indicative of an active seasonal migration by krill in the peninsula region. Potential drivers for such a migration include reduced advective losses and costs, and availability of sediment food resources within fjords. Seasonally near-shore krill may also affect stock and recruitment assessments and may have implications for managing the krill fishery in this area.

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“…Even though macronutrient concentrations in the water column during this period were low and uptake by phytoplankton was likely hampered, nutrients could still have been available through high bacterial remineralization, sloppy grazing, and/or viral lysis which peaks after the end of the bloom (Ducklow et al, 2012b;Brum et al, 2015). Additionally, the build-up of phytoplankton biomass could also have been ended by strong grazing, as is often observed at the sea ice edge, an attribute not covered in the RaTS program (Ross et al, 2008;Saba et al, 2014;Steinberg et al, 2015).…”

Section: Influence Of Presence/absence Of Sea Ice On Phytoplankton Dymentioning

confidence: 99%

Assessing Drivers of Coastal Primary Production in Northern Marguerite Bay, Antarctica

Rozema

Kulk

Veldhuis³

et al. 2017

Front. Mar. Sci.

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The coastal ocean of the climatically-sensitive west Antarctic Peninsula is experiencing changes in the physical and (photo)chemical properties that strongly affect the phytoplankton. Consequently, a shift from diatoms, pivotal in the Antarctic food web, to more mobile and smaller flagellates has been observed. We seek to identify the main drivers behind primary production (PP) without any assumptions beforehand to obtain the best possible model of PP. We employed a combination of field measurements and modeling to discern and quantify the influences of variability in physical, (photo)chemical, and biological parameters on PP in northern Marguerite Bay. Field data of high-temporal resolution (November 2013-March 2014) collected at a long-term monitoring site here were combined with estimates of PP derived from photosynthesis-irradiance incubations and modeled using mechanistic and statistical models. Daily PP varied greatly and averaged 1,764 mg C m −2 d −1 with a maximum of 6,908 mg C m −2 d −1 after the melting of sea ice and the likely release of diatoms concentrated therein. A non-assumptive random forest model (RF) with all possibly relevant parameters (M RFmax ) showed that variability in PP was best explained by light availability and chlorophyll a followed by physical (temperature, mixed layer depth, and salinity) and chemical (phosphate, total nitrogen, and silicate) water column properties. The predictive power from the relative abundances of diatoms, cryptophytes, and haptophytes (as determined by pigment fingerprinting) to PP was minimal. However, the variability in PP due to changes in species composition was most likely underestimated due to the contrasting strategies of these phytoplankton groups as we observed significant negative relations between PP and the relative abundance of flagellates groups. Our reduced model (M RFmin ) showed how light availability, chlorophyll a, and total nitrogen concentrations can be used to obtain the best estimate of PP (R 2 = 0.93). The resulting estimates from our models suggest summer PP to have been between 214.4 and 176.1 g C m −2 . Through the employment of a modeling technique without any assumptions apart from a representative sampling strategy, we showed and estimated how PP in this climatically sensitive and changing region can best be predicted and described.

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Long-term (1993–2013) changes in macrozooplankton off the Western Antarctic Peninsula

Cited by 153 publications

References 76 publications

Glacial melting: an overlooked threat to Antarctic krill

Glacial melting: an overlooked threat to Antarctic krill

Winter distribution and size structure of Antarctic krill Euphausia superba populations in-shore along the West Antarctic Peninsula

Assessing Drivers of Coastal Primary Production in Northern Marguerite Bay, Antarctica

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