Medieval versus recent environmental conditions in the Baltic Proper, what was different a thousand years ago?

Andrén, Elinor; Wirdum, Falkje van; Ivarsson, Lena Norbäck; Lönn, Mikael; Moros, Matthias; Andrén, Thomas

doi:10.1016/j.palaeo.2020.109878

Cited by 9 publications

(14 citation statements)

References 90 publications

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“…Our study has shown that the resting spore concentrations of the marine diatom Chaetoceros are very high during three ages (last century, MCA, and HTM) which correspond to times with high primary production, high sea surface temperatures (HTM, MCA), eutrophication (last century), and result in hypoxia (Zillén et al, 2008; Funkey et al, 2014). Recent studies have shown that increased salinity in the Baltic Proper caused increased hypoxic conditions and higher productivity of diatoms during the warm HTM conditions (van Wirdum et al, 2019) that also prevailed during MCA (E. Andrén et al, 2020). Warm climate creates a stronger stratification in the water mass resulting in hypoxic bottoms, but also enhances phosphorus recycling and sustaining cyanobacterial blooms which contribute to increase overall available nutrient concentrations (Funkey et al, 2014; Karlson et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

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Not dead yet: Diatom resting spores can survive in nature for several millennia

Sanyal

Larsson

Wirdum

et al. 2022

American J of Botany

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Premise Understanding the adaptive capacities of species over long timescales lies in examining the revived recent and millennia‐old resting spores buried in sediments. We show for the first time the revival, viability, and germination rate of resting spores of the diatom Chaetoceros deposited in sub‐seafloor sediments from three ages (recent: 0 to 80 years; ancient: ~1250 (Medieval Climate Anomaly) and ~6600 (Holocene Thermal Maximum) calendar year before present. Methods Recent and ancient Chaetoceros spores were revived to examine their viability and germination rate. Light and scanning electron microscopy and Sanger sequencing was done to identify the species. Results We show that ~6600 cal. year BP old Chaetoceros resting spores are still viable and that the vegetative reproduction in recent and ancient resting spores varies. The time taken to germinate is three hours to 2 to 3 days in both recent and ancient spores, but the germination rate of the spores decreased with increasing age. The germination rate of the recent spores was ~41% while that of the ancient spores were ~31% and ~12% for the ~1250 and ~6600 cal. year BP old resting spores, respectively. Based on the morphology of the germinated vegetative cells we identified the species as Chaetoceros muelleri var. subsalsum. Sanger sequences of nuclear and chloroplast markers identified the species as Chaetoceros muelleri. Conclusions We identify a unique model system, Chaetoceros muelleri var. subsalsum and show that recent and ancient resting spores of the species buried in sediments in the Baltic Sea can be revived and used for long‐term evolutionary studies.

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Section: Discussionmentioning

confidence: 99%

“…yr BP; Mann et al, 2009); and (3) the HTM (E. Andrén et al, 2000). The abundances of resting spores in sediments from the Baltic Basin are attributed to high primary production and eutrophication (E. Andrén et al, 1999, 2000) and also coincides with high temperatures and higher surface water salinities (Zillén et al, 2008; E. Andrén et al, 2020).…”

mentioning

confidence: 99%

Not dead yet: Diatom resting spores can survive in nature for several millennia

Sanyal

Larsson

Wirdum

et al. 2022

American J of Botany

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“…The higher salinity–adapted individuals appear in multiple sites in Poland, which would not have had high salinity–adapted communities spawning near the coast. While salinity conditions in the Baltic have changed slightly in the last 1,000 y ( 58 ), the changes were not significant enough that ocean-level salinity conditions would be present in the central Baltic. Strikingly, our samples from Truso, which date between 800 and 850 CE ( 21 ), show the presence of high salinity–adapted herring with Baltic-type inversions on chromosome 12 which could only stem from fishing operations in the Kattegat or western Baltic ( 37 ).…”

Section: Discussionmentioning

confidence: 99%

Population dynamics of Baltic herring since the Viking Age revealed by ancient DNA and genomics

Atmore

Martínez-García

Makowiecki

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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The world’s oceans are currently facing major stressors in the form of overexploitation and anthropogenic climate change. The Baltic Sea was home to the first “industrial” fishery ∼800 y ago targeting the Baltic herring, a species that is still economically and culturally important today. Yet, the early origins of marine industries and the long-term ecological consequences of historical and contemporary fisheries remain debated. Here, we study long-term population dynamics of Baltic herring to evaluate the past impacts of humans on the marine environment. We combine modern whole-genome data with ancient DNA (aDNA) to identify the earliest-known long-distance herring trade in the region, illustrating that extensive fish trade began during the Viking Age. We further resolve population structure within the Baltic and observe demographic independence for four local herring stocks over at least 200 generations. It has been suggested that overfishing at Øresund in the 16th century resulted in a demographic shift from autumn-spawning to spring-spawning herring dominance in the Baltic. We show that while the Øresund fishery had a negative impact on the western Baltic herring stock, the demographic shift to spring-spawning dominance did not occur until the 20th century. Instead, demographic reconstructions reveal population trajectories consistent with expected impacts of environmental change and historical reports on shifting fishing targets over time. This study illustrates the joint impact of climate change and human exploitation on marine species as well as the role historical ecology can play in conservation and management policies.

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“…The higher-salinity adapted individuals appear in multiple sites in Poland, which would not have had high-salinity adapted communities spawning near the coast. Salinity conditions in the Baltic have changed slightly in the last 1000 years 57 , but not significantly enough that ocean-level salinity conditions would be present in the central Baltic. Strikingly, our samples from Truso, which date between 800-850 CE 19 , show the presence of high-salinity adapted herring with Baltic-type inversions on chromosome 12 which could only stem from fishing operations in the Kattegat or western Baltic 36 .…”

Section: Population Assignmentmentioning

confidence: 99%

“…CBAS exhibit extremely low effective population size until the onset of the LIA (~700 YBP), at which point they increase dramatically until ~100 YBP. Sediment cores have shown that temperatures in the central Baltic during the MCA were warm enough to produce algal blooms and anoxic conditions 31,57,59 . Autumn spawning herring are more vulnerable to anoxic conditions than spring spawners as they spawn in deeper waters 60 .…”

Section: Central Baltic Autumn Spawnersmentioning

confidence: 99%

Serial depletion of Baltic herring since the Viking Age revealed by ancient DNA and population genomics

Atmore

Martínez-García

Makowiecki

et al. 2022

Preprint

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Marine resource consumption has been a key component in European diet and culture since the Middle Ages, when fish consumption increased dramatically. Yet, the early origins of marine industries and the long-term ecological consequences of historical and contemporary fisheries remain debated. The Baltic Sea was home to the first “industrial” fishery ∼800 years ago targeting the Baltic herring, a species that is still economically and culturally important today. We combine modern whole genome data with ancient DNA (aDNA) to identify the first known long-distance herring trade in the region, illustrating that large-scale fish trade began during the Viking Age. We resolve population structure within the Baltic and observe demographic independence for four local herring stocks over at least 200 generations. It has been suggested that overfishing at Øresund in the 16th century resulted in a demographic shift from autumn-spawning to spring-spawning herring dominance in the Baltic. We show that while the Øresund fishery had a negative impact on the western Baltic herring stock, the existence of autumn-spawning refugia in other regions of the Baltic delayed the demographic shift to spring spawning dominance until the 20th century. Importantly, modelling demographic trajectories over time, we identify a consistent pattern of serial depletion within the Baltic that is associated with changes in fishing pressure and climate, and conclude that herring exploitation at both historical and recent intensities is not sustainable. Our results highlight the complex and enduring impacts humans have had on the marine environment well before the industrial era.

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Medieval versus recent environmental conditions in the Baltic Proper, what was different a thousand years ago?

Cited by 9 publications

References 90 publications

Not dead yet: Diatom resting spores can survive in nature for several millennia

Not dead yet: Diatom resting spores can survive in nature for several millennia

Population dynamics of Baltic herring since the Viking Age revealed by ancient DNA and genomics

Serial depletion of Baltic herring since the Viking Age revealed by ancient DNA and population genomics

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