Irreversibility of regime shifts in the North Sea

Sguotti, Camilla; Blöcker, Alexandra M.; Färber, Leonie; Blanz, Benjamin; Cormier, Roland; Diekmann, Rabea; Letschert, Jonas; Rambo, Henrike; Stollberg, Nicole; Stelzenmüller, Vanessa; Stier, Adrian C.; Möllmann, Christian

doi:10.3389/fmars.2022.945204

Cited by 12 publications

(22 citation statements)

References 53 publications

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“…An asymmetry factor α controls the state of the system, thus inducing system changes, for instance from a regime A to a regime B. This factor is usually a linear model of an external driver that can be managed such as fishing effort in harvested ecosystem systems, or a combination of external drivers 45,49,50 (Fig.1). A second bifurcation factor β modifies the relationship between the asymmetry factor and the system state from linear continuous to non-linear and discontinuous, and thus shapes the functional form of system dynamics, i.e.…”

Section: Resultsmentioning

confidence: 99%

“…CUSPRA, similarly to both IRA and the stochastic cusp model, needs to fit a single vector (a time series) representing the system state to the model. The North Sea community index was built performing a PCA to a matrix of data coming from the Continuous Plankton Recorder (CPR) and International Bottom Trawl Survey (IBTS) 49 . SST derived from NOAA ErSST v5 and fishing effort from Couce at al.…”

Section: Methodsmentioning

confidence: 99%

“…2019, were used as drivers to test resilience 68,69 . The data ranged from 1985 to 2019 (for more info Sguotti et al, 2022a) (SI Fig.3) 49 . In the Mediterranean case example, a community dataset was built using landings data extracted from the database of the Food and Agriculture Organization (FAO) of the United Nations and then reduced using a PCA 35 .…”

Section: Methodsmentioning

confidence: 99%

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Resilience assessment in complex natural systems

Sguotti,

Vasilakopoulos,

Tzanatos

et al. 2023

Preprint

Self Cite

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Ecological resilience is the capability of an ecosystem to maintain the same structure and function and to avoid crossing catastrophic tipping points. While fundamental for management, concrete ways to estimate and interpret resilience in real ecosystems are still lacking. Here, we develop an empirical approach to estimate resilience based on the stochastic cusp model derived from catastrophe theory. Our Cusp Resilience Assessment (CUSPRA) has three characteristics: i) it provides estimates on how likely a system is to cross a tipping point characterized by hysteresis, ii) it assesses resilience in relation to multiple external drivers, and iii) it produces straightforward results for ecosystem-based management. We validated our approach using simulated data and demonstrated its application using empirical time-series of an Atlantic cod population and of marine ecosystems in the North and the Mediterranean Sea. We show that CUSPRA provides a powerful method to empirically estimate resilience in support of a sustainable management of our constantly adapting ecosystems under global climate change.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Resilience assessment in complex natural systems

Sguotti,

Vasilakopoulos,

Tzanatos

et al. 2023

Preprint

Self Cite

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show abstract

“…With the development of new metrics describing ecological communities, such as functional composition, ecologists are likely to be confronted increasingly with this question of integration of different metrics. Answering this question is outside the scope of the present paper, but it is one of the many problems with the concept of regime shifts [other problems include detectability (Hillebrand et al, 2020) and the presence or absence of hysteresis (Sguotti et al, 2022)]. We suggest that achieving a better, more formal agreement on what is a regime shift is an important research agenda.…”

Section: Conclusion: Plankton Functional Traits and North Sea Regime ...mentioning

confidence: 93%

“…Although these events undoubtedly represent important changes in the plankton communities of the North Sea, their characterization as “regime shifts” is a subject of debate (Sguotti et al, 2022). In the case of the North Sea, a regime shift is generally described as a large‐scale, sudden and durable change in the abundance and/or composition of the community of interest (see e.g., Beaugrand, 2004).…”

Section: Introductionmentioning

confidence: 99%

Reinterpreting two regime shifts in North Sea plankton communities through the lens of functional traits

Djeghri

Boyé

Ostle

et al. 2023

Global Ecol Biogeogr

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Aim The so‐called regime shifts in North Sea plankton communities provide an important historical case study to understand marine regime shifts. Previous studies characterized regime shifts using a variety of community metrics (e.g., indicator species abundances, taxonomic composition and chlorophyll biomass) but left the functional traits of plankton unassessed. Here, we explicitly re‐assess the historically recognized North Sea regime shifts through the lens of plankton functional traits to gain a better understanding of these events. Location The North Sea (NW European shelf). Time period 1958–2018, focusing on the 1980s and 1996–2003 regime shifts. Major taxa studied Marine phyto‐ and zooplankton. Methods We compute trait spaces for both phyto‐ and zooplankton of the North Sea using traits from the literature and a Gower's distance‐based method. Using abundance data from the Continuous Plankton Recorder Survey, we then compute monthly time series of the centroids of the communities, an indicator of functional composition. We then use principal component analysis on the centroids to assess the main temporal changes in plankton functional composition associated with the 1980s and 1996–2003 regime shifts. Results Little change in plankton functional composition was associated with the 1980s regime shift. In contrast, the functional composition of plankton communities changed markedly after the 1996–2003 regime shift, with an increase in the summer relative abundance of non‐motile autotrophs (i.e., diatoms) and the spring relative abundance of meroplankton. Main conclusions The North Sea regime shifts were not associated systematically with changes in functional composition, calling into question the definition of regime shifts and illustrating the importance of taking different metrics into account to interpret ecological events accurately. Taking into account functional composition, we interpret the 1980s so‐called regime shift as a latitudinal shift in communities that was insufficient to impact functional composition and the 1996–2003 so‐called regime shift as a period of change in bentho‐pelagic coupling.

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Modeling the effects of selectively fishing key functional groups of herbivores on coral resilience

Cook,

Schmitt,

Holbrook

et al. 2024

Ecosphere

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Mounting evidence suggests that fishing can be a major driver of coral‐to‐macroalgae regime shifts on tropical reefs. In many small‐scale coral reef fisheries, fishers target herbivorous fishes, which can weaken coral resilience via reduced herbivory on macroalgae that then outcompete corals. Previous models that explored the effects of harvesting herbivores revealed hysteresis in the herbivory–benthic state relationship that results in bistability of coral‐ and macroalgae‐dominated states over some levels of fishing pressure, which has been supported by empirical evidence. However, past models have not accounted for the functional differences among herbivores or how fisher selectivity for different herbivore functional groups may alter the benthic dynamics and resilience. Here, we use a dynamic model that links differential fishing on two key herbivore functional groups to the outcome of competitive dynamics between coral and macroalgae. We show that reef state depends not only on the level of fishing but also on the types of herbivores targeted by fishers. Selectively fishing browsing herbivores that are capable of consuming mature macroalgae (e.g., unicornfish) increases precariousness of the coral state by moving the system close to the coral‐to‐macroalgae tipping point. By contrast, selectively harvesting grazing herbivores that are only capable of preventing macroalgae from becoming established (e.g., parrotfishes) can increase catch yields substantially more before the tipping point is reached. However, this lower precariousness with increasing fishing effort comes at the cost of increasing the range of fishing effort over which coral and macroalgae are bistable; increasing hysteresis makes a regime shift triggered by a disturbance more difficult or impractical to reverse. Our results suggest that management strategies for small‐scale coral reef fisheries should consider how functional differences among harvested herbivores coupled with fisher selectivity influence benthic dynamics in light of the trade‐off between tipping point precariousness and coral recovery dynamics following large disturbances.

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Irreversibility of regime shifts in the North Sea

Cited by 12 publications

References 53 publications

Resilience assessment in complex natural systems

Resilience assessment in complex natural systems

Reinterpreting two regime shifts in North Sea plankton communities through the lens of functional traits

Modeling the effects of selectively fishing key functional groups of herbivores on coral resilience

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