The rise of novelty in marine ecosystems: The Baltic Sea case

Ammar, Yosr; Niiranen, Susa; Otto, Saskia A.; Möllmann, Christian; Finsinger, Walter; Blenckner, Thorsten

doi:10.1111/gcb.15503

Cited by 16 publications

(18 citation statements)

References 117 publications

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“…1971-2013 (Törnroos et al, 2019). First-time observations of known fish species in sub-basins where they were not previously caught have been related to increasing spring temperatures (+3-6 °C during 1980-2015; (Ammar et al, 2021). Such potential temporal patterns were not analyzed here, where we merged the fish incidence data across years to narrow down likely SR estimates for different sub-basins and focused on large-scale spatial patterns.…”

Section: Discussionmentioning

confidence: 99%

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

Koehler

Erlandsson

Karlsson

et al. 2021

Preprint

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Abstract. Coastal ecosystems are biologically productive and their diversity underlies various ecosystem services to humans. However, large-scale species richness (SR) and its regulating factors remain uncertain for many organism groups, owing not least to the fact that observed SR (SRobs) is strongly dependent on sample size and inventory completeness (IC). We estimated changes in SR across a natural geographical gradient using statistical rarefaction and extrapolation methods, based on a large fish species incidence dataset compiled from Swedish fish survey databases. The data covered nearly five decades (1975–2020), a 1,300 km north-south distance and a 10-fold salinity gradient along sub-basins of the Baltic Sea plus Skagerrak. Focusing on shallow coastal and offshore areas (< 30 m depth), we calculated standardized SR (SRstd) and estimated SR (SRest), and related these to sub-basin annual mean salinity and water temperature. IC was high, 98.5 %–99.9 %, in the 10 sub-basins with sufficient data for analysis. The recorded fish species were of 75 % marine and 25 % freshwater origin. Total fish SRobs was 144 for shallow coastal areas, and 110 for shallow offshore areas. Sub-basin specific SRest for coastal areas varied between 35 ± 7 (SE) and 109 ± 6 fish species, and was ca. three times higher in the most saline (salinity 29-32) compared to the least saline sub-basins (salinity 2.7). Completing information on functional attributes showed that differences along the salinity gradient reflected an increased share of coastal resident fish species in lower salinities, and a higher share of migratory fish at higher salinities. The proportion of benthic and demersal fish species was also lower in the least saline sub-basins, and increased with increasing salinity. If climate change lowers the salinity regime of the Baltic Sea in the future this may hence influence the SR and community composition of fish.

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Section: Discussionmentioning

confidence: 99%

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

Koehler

Erlandsson

Karlsson

et al. 2021

Preprint

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“…The marine food webs of the Baltic Sea have been, and are projected to be, impacted by climate change-related variables by altering the physical environment for several species, by impacting microevolution of species in the Baltic Sea, and by synergistic effects of climate change and other environmental drivers such as eutrophication and hypoxia (Niiranen et al, 2013;Wikner and Andersson, 2012;Schmidt et al, 2020;Pecuchet et al, 2020;Ehrnsten et al, 2020). It has even been shown that the entire ecosystem may fulfil criteria for becoming a novel system with profoundly altered energy-pathways (Ammar et al, 2021). Below, recent findings regarding specifically climate impacts on trophic structure and functioning on the Baltic Sea ecosystem are summarized.…”

Section: Climate Change and Ecosystem Structure And Functionmentioning

confidence: 99%

Global climate change and the Baltic Sea ecosystem: direct and indirect effects on species, communities and ecosystem functioning

Viitasalo

Bonsdorff

2021

Preprint

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Abstract. Climate change has multiple direct and indirect potentially synergistic effects on Baltic Sea species, organism communities, and on ecosystem functioning, through physical and biogeochemical environmental characteristics of the sea. Associated indirect and secondary effects on species interactions, trophic dynamics and ecosystem function are expected to be significant. Evidence on effects of climate are compiled from and reviewed for field studies, experimental work, as well as modelling studies primarily from published literature after 2010. The responses vary within and between species groups, even between sibling species. Such subtle differences, as well as secondary feedbacks and altered trophic pathways, make projections difficult. Some common patterns arise from the wealth of recent studies, however. It is likely that the combined effects of increased external nutrient loads, stratification and internal loading will improve the conditions for cyanobacterial blooms in large parts of the Baltic. In the northernmost areas the increasing allochtonous DOM may further complicate the picture by increasing heterotrophy and by decreasing food web efficiency. This effect may, however, be counteracted by the intensification of the bacteria-flagellate-microzooplankton-mesozooplankton link, which may change the system from a bottom-up controlled one to a top-down controlled one. In deep benthic communities, continued eutrophication may promote higher sedimentation of organic matter and increase zoobenthic biomasses, but eventually increasing stratification and hypoxia/anoxia will disrupt benthic-pelagic coupling, leading to reduced benthic biomass. In the photic benthic systems warmer winters with less ice and nutrient increase enhances eutrophication. The projected salinity decline suppresses marine species, and temperature increase overgrowth of perennial macroalgae by annual filamentous alga throughout the growing-season, and major changes in the marine entire ecosystem are expected. The changes in environmental conditions probably also lead to increased establishment of non-indigenous species, potentially affecting food web dynamics in large areas of the Baltic Sea. However, several modelling studies have concluded that nutrient reductions according to the Baltic Sea Action Plan of Helsinki Commission may be a stronger driver for ecosystem functions in the Baltic Sea than climate change. Such studies highlight the importance of studying the Baltic Sea as an interlinked socio-ecological system. Knowledge gaps include uncertainties in projecting the future salinity level as well as stratification under different climate forcings. This weakens our ability to project how overall biodiversity, pelagic productivity, fish populations, and macroalgal communities may change in the future. Experimental work must be better integrated into studies of food web dynamics, to get a more comprehensive view of the responses of the pelagic and benthic systems to climate change, from bacteria to fish. Few studies have holistically investigated the shallow water ecosystems holistically. There are complex climate-induced interactions and multiple feedbacks between algae, grazers and their predators, that are poorly known, as are the effects of non-native invasive species. Finally, both 2D species distribution models and 3D ecosystem models could benefit from better integration of approaches including physical, chemical and biological parameters.

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“…Earlier studies indicate that climate change, eutrophication, and overfishing, have resulted in structural and functional changes of food webs (Pecuchet et al, 2019;Törnroos et al, 2019), and ecosystem regime shifts in different parts of the Baltic Sea (e.g., Möllmann et al, 2009;Lindegren et al, 2012;Olsson et al, 2015;Eklöf et al, 2020). Recently, it has been found that novel biotic and abiotic conditions have increasingly appeared in the Baltic Sea in the past decades (Ammar et al, 2021). Future Baltic Sea projections indicate large increases in seawater temperature, decreases in salinity (Meier et al, 2012;Andersson et al, 2015;Saraiva et al, 2019) with severe changes in species and food-webs (Niiranen et al, 2013;Bauer et al, 2018Bauer et al, , 2019.…”

Section: Introductionmentioning

confidence: 99%

The Risk for Novel and Disappearing Environmental Conditions in the Baltic Sea

et al. 2021

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Future climate biogeochemical projections indicate large changes in the ocean with environmental conditions not experienced at present referred to as novel, or may even disappear. These climate-induced changes will most likely affect species distribution via changes in growth, behavior, evolution, dispersal, and species interactions. However, the future risk of novel and disappearing environmental conditions in the ocean is poorly understood, in particular for compound effects of climate and nutrient management changes. We map the compound risk of the occurrence of future novel and disappearing environmental conditions, analyze the outcome of climate and nutrient management scenarios for the world’s largest estuary, the Baltic Sea, and the potential consequences for three charismatic species. Overall, the future projections show, as expected, an increase in environmental novelty over time. The future nutrient reduction management that improves the eutrophication status of the Baltic Sea contributes to large novel and disappearing conditions. We show the consequences of novel and disappearing environmental conditions for fundamental niches of three charismatic species under different scenarios. This first step toward comprehensively analyzing environmental novelty and disappearing conditions for a marine system illustrates the urgent need to include novelty and disappearing projection outputs in Earth System Models. Our results further illustrate that adaptive management is needed to account for the emergence of novelty related to the interplay of multiple drivers. Overall, our analysis provides strong support for the expectation of novel ecological communities in marine systems, which may affect ecosystem services, and needs to be accounted for in sustainable future management plans of our oceans.

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The rise of novelty in marine ecosystems: The Baltic Sea case

Cited by 16 publications

References 117 publications

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

Global climate change and the Baltic Sea ecosystem: direct and indirect effects on species, communities and ecosystem functioning

The Risk for Novel and Disappearing Environmental Conditions in the Baltic Sea

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