Marine Heatwaves Characteristics in the Barents Sea Based on High Resolution Satellite Data (1982–2020)

Abstract

Marine heatwaves (MHWs) can potentially alter ocean ecosystems with far-reaching ecological and socio-economic consequences. This study investigates the spatiotemporal evolution of the main MHW characteristics in the Barents Sea using high-resolution (0.25° × 0.25°) daily Sea Surface Temperature (SST) data from 1982 to 2020. The results reveal that the Barents Sea has experienced accelerated warming and several more MHWs in recent decades. Since 2004, an amplified increasing SST trend was observed across the entire Barents Sea, with a spatially averaged SST trend of 0.25 ± 0.18°C/decade and 0.58 ± 0.21°C/decade for the northern and southern Barents Sea, respectively. The annual mean MHW frequency, days, and duration over the entire Barents Sea increased by, respectively, 62, 73, and 31% from the pre- to the post-2004 period. More than half of all MHW days occurred in the last decade (2011–2020). The most intense MHW event occurred in summer 2016, which was also the warmest year during the study period. In general, the annual mean MHW frequency was relatively high in the northern Barents Sea, while the intensity and duration were higher in the southern Barents Sea. The highest annual MHW intensity and duration were observed in 2016, 2013, and 2020, respectively, while the highest annual MHW frequency was found in 2016. For the entire Barents Sea, the annual MHW frequency and duration increased significantly (p < 0.05) over the whole study period, with a trend of, respectively, 1.0 ± 0.4 events/decade, which is a doubling of the global average, and 2.4 ± 1.3 days/decade. In terms of the influence of climate variability on MHW characteristics, our findings revealed that the Eastern Atlantic Pattern (EAP) plays a significant role in controlling MHW characteristics, whereas the North Atlantic Oscillation (NAO) has no significant relationship. Sea ice concentrations were found to have a significant negative correlation with MHW characteristics. Strong positive correlations were observed between SST, surface air temperature, and MHW frequency, implying that as global warming continues, we can expect continued rising in MHW frequencies and days in the Barents Sea with huge implications for the ocean ecosystem.

Successive extreme climatic events lead to immediate, large‐scale, and diverse responses from fish in the Arctic

“…We detected multiple ECEs in recent years in the heat content of the upper water column in 2006, 2013, and 2016 as well as in June SIE in 2012. These results are confirmed by a recent study focusing specifically on marine heatwaves and using daily data of sea surface temperatures (SST) from 1982 to 2020 identified the same heatwaves in the Barents Sea in 2013 and 2016, negatively correlated with sea ice concentrations (Mohamed et al, 2022). Marine heatwaves in 2006 and 2012 were frequent in the north, but with a much lower cumulative intensity than 2013 and 2016.…”

“…Mohamed et al (2022) showed that marine heatwaves tended to be more frequent in the North of Barents Sea, and more intense and longer in the South. The 2006, 2012, and 2016 heatwaves were more frequent but less intense in the Northern Barents Sea than in the South (Mohamed et al, 2022). In our study, the relative change in environmental conditions in those years was also less extreme in the Atlantic than in the Arctic (Figure S9).…”

“…Our results may seem counterintuitive as one would expect arctic species to retract during warm years, while they rather seem to expand and increase in abundance. Our two main hypotheses are (i) that the potentially early and extended productive period might have benefitted also arctic species, allowing for a better survival, especially during the two first milder heatwaves of 2006 and 2012 (Mohamed et al, 2022), (ii) that the observed increases in density and geographical extent could be linked to arctic species expanding and aggregating in cooler, more suitable habitats, while still being present in lesser abundances at the trailing edge of their distribution, thus artificially inflating their density in the hauls. and spatial scales (Boyd et al, 2016;Smale et al, 2017), with different impacts on their life stages depending on sensitivity bottlenecks (Dahlke et al, 2020;Madeira et al, 2020), as well as indirect responses through species interactions.…”

“…Dotted lines indicate minimum and maximum values of each time seriesSecond, differences in timing and intensity of response from the various functional groups could be linked to the various nature and strength of the ECEs in the different oceanographic domains Mohamed et al (2022). showed that marine heatwaves tended to be more frequent in the North of Barents Sea, and more intense and longer in the South.The 2006, and 2016 heatwaves were more frequent but less intense in the Northern Barents Sea than in the South(Mohamed et al, 2022). In our study, the relative change in environmental conditions in those years was also less extreme in the Atlantic than in the Arctic (FigureS9).…”

“…They could also be linked to the different ecological context in which each event occurs, caused for example by other conditions not included in the analysis, such as interspecific interactions. Future studies could update the data used here to include more data points and ECEs (e.g., the 2020 heatwave,Mohamed et al, 2022)), to statistically link the observed temporal and spatial patterns across fish communities with the environmental conditions. This was unfortunately not possible in our study, owing to the low number of data points in the time series.4.2 | The spatial imprint of ECEs and functional group tolerances modulate specific responsesConsistent ecological signatures of the ECEs were observed at the community level, yet there were divergences in functional group responses to the different ECEs.…”