Large scale patches of Calanus finmarchicus and associated hydrographic conditions off the Lofoten archipelago

Weidberg, Nicolás; Hernández, Néstor Santana; Renner, Angelika; Falk‐Petersen, Stig; Basedow, Sünnje Linnéa

doi:10.1016/j.jmarsys.2021.103697

Cited by 4 publications

(3 citation statements)

References 81 publications

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“…We consider the assumption of no extra horizontal diffusion acceptable for our purpose as the spatial resolution of the ocean model is relatively high. The sizes of detected patches were in the mesoscale range (10-100 km; Vogedes et al, 2014) and were within the sizes of observed zooplankton patches along the Norwegian coast and in the Barents Sea (Trudnowska et al, 2016;Basedow et al, 2019;Weidberg et al, 2022). Study of patchiness in zooplankton suggested an increasing number of patches associated with a decreasing patch size (Piontkovski et al, 1997).…”

Section: Discussionsupporting

confidence: 69%

Assessing the patchiness of early life stage of a fish stock (Gadus morhua) and its contribution to the stock recruitment

2022

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Patchiness, defined as spatial heterogeneity in distribution of organisms, is a common phenomenon in zooplankton including ichtyoplankton. In heterogeneous landscapes, depending on the scale of prey and predatory distributions, individuals in patches may experience distinct differences in the survival rate compared to individuals distributed more homogeneously outside patches. In this study, we focused on drifting eggs and larvae of Northeast Arctic (NEA) cod, one of the largest exploited fish stock in the world. The eggs and larvae are largely distributed along the north-western coast of Norway and northern Russia. We ask to what degree individuals are located in patches contribute to the species recruitment. For this purpose, we developed a patch recognition method to detect the existence of patches in particle tracking simulations using a connected-component labeling algorithm. We then assessed the contribution of individuals in detected patches to the total recruitment. Our results showed that depending on year, day of year, and resolution scale for detection of patches, recruits present in patches can vary between 0.6% and 38.7% with an average of 20.4% of total recruitment. The percentage decreased with increasing day of year in the drifting season but increased with decreasing patch resolution scale, down to the finest investigated scale of 8 km. On the basis of these results, we advise field recruitment studies of NEA cod to at least resolve an 8-km spatial scale to capture effects of spatial heterogeneity in the survival rate on the species recruitment.

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Section: Discussionsupporting

confidence: 69%

Assessing the patchiness of early life stage of a fish stock (Gadus morhua) and its contribution to the stock recruitment

2022

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“…The eastward expansion of less dense surface waters of the NCW might also aggregate ascending copepods on the shelf when they migrate into these NCW surface waters after overwintering (Weidberg et al., 2022). In this process, the vertical migration of copepods is essential; therefore, the intrusion onto the shelf in spring is likely a combination of physical processes (aggregation at shelf break, eastward expansion of NCW, eddies) and biological drivers (surface migration of copepods).…”

Section: Discussionmentioning

confidence: 99%

Dynamical Controls of the Eastward Transport of Overwintering Calanus finmarchicus From the Lofoten Basin to the Continental Slope

et al. 2022

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Diapausing populations of Calanus finmarchicus at depth in the Lofoten Basin (LB) return to the continental shelf and slope off the Lofoten‐Vesterålen Islands during the phytoplankton spring bloom to feed and spawn, forming surface swarms with a great abundance. To study how overwintering populations of C. finmarchicus move with the deep currents and return to the shelf, Lagrangian transport characteristics of particles in deep water between 2008 and 2019 were analyzed using Global Ocean Reanalysis and Simulation re‐analysis data and Lagrangian Coherent Structures (LCSs). Our analyses revealed that persistent eastward transport of diapausing C. finmarchicus between LB and continental slope occurred mainly between 600 and 1,100 m in the Arctic Intermediate Water. The consistency of the vertical distributions of C. finmarchicus abundance and salinity further suggests that physical factors control the horizontal distribution of the species. Hovmöller diagrams of kinetic energy indicate that there is an eastward advection of mean current at depth. The co‐occurrence between the eastward transport of LCSs and the eastward advection of the mean current provides direct evidence that the life history of C. finmarchicus is subjected to physical control in the Norwegian Sea.

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“…The wide range in salinity (31.5-34°C), temperature (6-9°C) and CDOM (1-2.5 ppb) reveals that the USV AutoNaut traveled through many distinct water masses, some with more or less influence from Trondheim's fjord. Strong mesoscale patchiness with contrasting distributions of phytoplankton (the dinoflagellate Tripos) and zooplankton, including copepods swarms, has been observed in other coastal region of Norway (Basedow et al, 2019;Fragoso et al, 2022;Weidberg et al, 2022), revealing the importance of spatial observation for understanding plankton dynamics. In our study, satellite images revealed that phytoplankton spatial distribution in a large area of Frohavet is highly patchy, yet widespread across Frohavet over the bloom period.…”

Section: Phytoplankton Dynamics From Usv Buoy and Satellite Observationsmentioning

confidence: 98%

The Role of Rapid Changes in Weather on Phytoplankton Spring Bloom Dynamics From Mid‐Norway Using Multiple Observational Platforms

Fragoso,

Dallolio,

Grant

et al. 2024

JGR Oceans

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The spring phytoplankton bloom plays a major role in pelagic ecosystems; however, its dynamics are not well understood due to insufficient, highly resolved observational data. Here we investigate the start, peak, and decline of a 2‐week phytoplankton spring bloom in Frohavet located in a biological hotspot of the coast of mid‐Norway. We used observations from an uncrewed surface vehicle (USV) combined with buoy measurements, satellite images, discrete water sampling and modeling approaches. The spring bloom (March–June 2022) consisted of multiple peaks (up to 5 mg Chla m−3), with a long peak in April dominated by the diatom Skeletonema, coincident with the period when the USV captured the temporal and spatial dynamics of the bloom. Short‐term episode of calm weather in spring, such as clear skies and consistent low wind speed (<7 m s−1) shoaled the mixed layer depth (<15 m) and promoted the rapid development of the spring bloom ‐ from 1 to 5 mg Chla m−3 in 5 days. Likewise, the collapse of the bloom was rather quick, 1–2 days and coincides with low nitrate values and rapid increase in wind speed (>10 m s−1), suggesting strong influence of the environment on phytoplankton dynamics. Understanding the dynamics of the spring bloom is crucial for predicting its impact on marine trophic web and biogeochemical cycles. Integration of distinct observational platforms has the potential to unveil the environmental factors underlying phytoplankton bloom dynamics.

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Large scale patches of Calanus finmarchicus and associated hydrographic conditions off the Lofoten archipelago

Cited by 4 publications

References 81 publications

Assessing the patchiness of early life stage of a fish stock (Gadus morhua) and its contribution to the stock recruitment

Assessing the patchiness of early life stage of a fish stock (Gadus morhua) and its contribution to the stock recruitment

Dynamical Controls of the Eastward Transport of Overwintering Calanus finmarchicus From the Lofoten Basin to the Continental Slope

The Role of Rapid Changes in Weather on Phytoplankton Spring Bloom Dynamics From Mid‐Norway Using Multiple Observational Platforms

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