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Durant JM, Holt RE, Langangen Ø. Large biomass reduction effect on the relative role of climate, fishing, and recruitment on fish population dynamics. Sci Rep 2024; 14:8995. [PMID: 38637592 PMCID: PMC11026439 DOI: 10.1038/s41598-024-59569-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 04/12/2024] [Indexed: 04/20/2024] Open
Abstract
Many species around the world have collapsed, yet only some have recovered. A key question is what happens to populations post collapse. Traditionally, marine fish collapses are linked to overfishing, poor climate, and recruitment. We test whether the effect on biomass change from these drivers remains the same after a collapse. We used a regression model to analyse the effect of harvesting, recruitment, and climate variability on biomass change before and after a collapse across 54 marine fish populations around the world. The most salient result was the change in fishing effect that became weaker after a collapse. The change in sea temperature and recruitment effects were more variable across systems. The strongest changes were in the pelagic habitats. The resultant change in the sensitivity to external drivers indicates that whilst biomass may be rebuilt, the responses to variables known to affect stocks may have changed after a collapse. Our results show that a general model applied to many stocks provides useful insights, but that not all stocks respond similarly to a collapse calling for stock-specific models. Stocks respond to environmental drivers differently after a collapse, so caution is needed when using pre-collapse knowledge to advise on population dynamics and management.
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Affiliation(s)
- Joël M Durant
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, NO-0316, Oslo, Norway.
| | - Rebecca E Holt
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, NO-0316, Oslo, Norway
- Centre for Environment, Fisheries, and Aquaculture Science (Cefas), Weymouth, DT4 8UB, UK
| | - Øystein Langangen
- Section for Aquatic Biology and Toxicology (AQUA), Department of Biosciences, University of Oslo, NO-0316, Oslo, Norway
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2
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Durant JM, Ono K, Langangen Ø. Empirical evidence of nonlinearity in bottom up effect in a marine predator-prey system. Biol Lett 2022; 18:20220309. [PMID: 36321432 PMCID: PMC9627449 DOI: 10.1098/rsbl.2022.0309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The strength of species interactions may have profound effects on population dynamics. Empirical estimates of interaction strength are often based on the assumption that the interaction strengths are constant. Barents Sea (BS) cod and capelin are two fish populations for which such an interaction has been acknowledged and used, under the assumption of constant interaction strength, when studying their population dynamics. However, species interactions can often be nonlinear in marine ecosystems and might profoundly change our understanding of food chains. Analysing long-term time series data comprising a survey over 37 years in the Arcto-boreal BS, using a state-space modelling framework, we demonstrate that the effect of capelin on cod is not linear but shifts depending on capelin abundance: while capelin is beneficial for cod populations at high abundance; below the threshold, it becomes less important for cod. Our analysis therefore shows the importance of investigating nonlinearity in species interactions and may contribute to an improved understanding on species assemblages.
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Affiliation(s)
- Joël M. Durant
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, NO-0316 Oslo, Norway
| | - Kotaro Ono
- Institute for Marine Research (IMR), PO Box 1870 Nordnes, Bergen 5817, Norway
| | - Øystein Langangen
- Section for Aquatic Biology and Toxicology (AQUA), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, NO-0316 Oslo, Norway
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3
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Durant JM, Aarvold L, Langangen Ø. Stock collapse and its effect on species interactions: Cod and herring in the Norwegian-Barents Seas system as an example. Ecol Evol 2021; 11:16993-17004. [PMID: 34938487 PMCID: PMC8668721 DOI: 10.1002/ece3.8336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 10/19/2021] [Accepted: 10/22/2021] [Indexed: 11/25/2022] Open
Abstract
Both the Norwegian Spring Spawning herring (Clupea harengus) and the Northeast Arctic (NEA) cod (Gadus morhua) are examples of strong stock reduction and decline of the associated fisheries due to overfishing followed by a recovery. Cod and herring are both part of the Barents Sea ecosystem, which has experienced major warming events in the early (1920-1940) and late 20th century. While the collapse or near collapse of these stocks seems to be linked to an instability created by overfishing and climate, the difference of population dynamics before and after is not fully understood. In particular, it is unclear how the changes in population dynamics before and after the collapses are associated with biotic interactions. The combination of the availability of unique long-term time series for herring and cod makes it a well-suited study system to investigate the effects of collapse. We examine how species interactions may differently affect the herring and cod population dynamic before and after a collapse. Particularly we explore, using a GAM modeling approach, how herring could affect cod and vice versa. We found that the effect of cod biomass on herring that was generally positive (i.e., covariation) but the effect became negative after the collapse (i.e., predation or competition). Likewise a change occurred for the cod, the juvenile herring biomass that had no effect before the collapse had a negative effect after. Our results indicate that the population collapses may alter the inter-specific interactions and response to abiotic environmental changes. While the stocks are at similar abundance levels before and after the collapses, the system is potentially different in its functioning and may require different management action.
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Affiliation(s)
- Joël M. Durant
- Centre for Ecological and Evolutionary Synthesis (CEES)Department of BiosciencesUniversity of OsloOsloNorway
| | - Leana Aarvold
- Centre for Ecological and Evolutionary Synthesis (CEES)Department of BiosciencesUniversity of OsloOsloNorway
| | - Øystein Langangen
- Section for Aquatic biology and toxicology (AQUA)Department of BiosciencesUniversity of OsloOsloNorway
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4
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Harvesting forage fish can prevent fishing-induced population collapses of large piscivorous fish. Proc Natl Acad Sci U S A 2021; 118:1917079118. [PMID: 33531361 DOI: 10.1073/pnas.1917079118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fisheries have reduced the abundances of large piscivores-such as gadids (cod, pollock, etc.) and tunas-in ecosystems around the world. Fisheries also target smaller species-such as herring, capelin, and sprat-that are important parts of the piscivores' diets. It has been suggested that harvesting of these so-called forage fish will harm piscivores. Multispecies models used for fisheries assessments typically ignore important facets of fish community dynamics, such as individual-level bioenergetics and/or size structure. We test the effects of fishing for both forage fish and piscivores using a dynamic, multitrophic, size-structured, bioenergetics model of the Baltic Sea. In addition, we analyze historical patterns in piscivore-biomass declines and fishing mortalities of piscivores and forage fish using global fish-stock assessment data. Our community-dynamics model shows that piscivores benefit from harvesting of their forage fish when piscivore fishing mortality is high. With substantial harvesting of forage fish, the piscivores can withstand higher fishing mortality. On the other hand, when piscivore fishing mortality is low, piscivore biomass decreases with more fishing of the forage fish. In accordance with these predictions, our statistical analysis of global fisheries data shows a positive interaction between the fishing mortalities of forage-fish stocks and piscivore stocks on the strength of piscivore-biomass declines. While overfishing of forage fish must be prevented, our study shows that reducing fishing pressures on forage fish may have unwanted negative side effects on piscivores. In some cases, decreasing forage-fish exploitation could cause declines, or even collapses, of piscivore stocks.
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5
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Lehtinen SO. Ecological and evolutionary consequences of predator-prey role reversal: Allee effect and catastrophic predator extinction. J Theor Biol 2020; 510:110542. [PMID: 33242490 DOI: 10.1016/j.jtbi.2020.110542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 11/25/2022]
Abstract
In many terrestrial, marine, and freshwater predator-prey communities, young predators can be vulnerable to attacks by large prey. Frequent prey counter-attacks may hinder the persistence of predators. Despite the commonness of such role reversals in nature, they have rarely been addressed in evolutionary modelling. To understand how role reversals affect ecological and evolutionary dynamics of a predator-prey community, we derived an ecological model from individual-level processes using ordinary differential equations. The model reveals complex ecological dynamics, with possible bistability between alternative coexistence states and an Allee effect for the predators. We find that when prey counter-attacks are frequent, cannibalism is necessary for predator persistence. Using numerical analysis, we also find that a sudden ecological shift from coexistence to predator extinction can occur through several catastrophic bifurcations, including 'saddle-node', 'homoclinic', and 'subcritical Hopf'. The analysis of single-species evolution reveals that predator selection towards increasing or decreasing cannibalism triggers a catastrophic shift towards an extinction state of the predators. Such an evolutionary extinction of the predators may also be caused by prey selection towards increasing foraging activity because it facilitates encounters with vulnerable, young predators. The analysis of predator-prey coevolution further demonstrates that predator's catastrophic extinction becomes an even more likely outcome than in single-species evolution. Our results suggest that when young predators are vulnerable to prey attacks, a sudden extinction of the predators may be more common than currently understood.
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Affiliation(s)
- Sami O Lehtinen
- Department of Mathematics and Statistics, University of Helsinki, FIN-00014, Finland.
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6
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Durant JM, Ono K, Stenseth NC, Langangen Ø. Nonlinearity in interspecific interactions in response to climate change: Cod and haddock as an example. GLOBAL CHANGE BIOLOGY 2020; 26:5554-5563. [PMID: 32623765 DOI: 10.1111/gcb.15264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/14/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Climate change has profound ecological effects, yet our understanding of how trophic interactions among species are affected by climate change is still patchy. The sympatric Atlantic haddock and cod are co-occurring across the North Atlantic. They compete for food at younger stages and thereafter the former is preyed by the latter. Climate change might affect the interaction and coexistence of these two species. Particularly, the increase in sea temperature (ST) has been shown to affect distribution, population growth and trophic interactions in marine systems. We used 33-year long time series of haddock and cod abundances estimates from two data sources (acoustic and trawl survey) to analyse the dynamic effect of climate on the coexistence of these two sympatric species in the Arcto-Boreal Barents Sea. Using a Bayesian state-space threshold model, we demonstrated that long-term climate variation, as expressed by changes of ST, affected species demography through different influences on density-independent processes. The interaction between cod and haddock has shifted in the last two decades due to an increase in ST, altering the equilibrium abundances and the dynamics of the system. During warm years (ST over ca. 4°C), the increase in the cod abundance negatively affected haddock abundance while it did not during cold years. This change in interactions therefore changed the equilibrium population size with a higher population size during warm years. Our analyses show that long-term climate change in the Arcto-Boreal system can generate differences in the equilibrium conditions of species assemblages.
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Affiliation(s)
- Joël M Durant
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Kotaro Ono
- Institute for Marine Research (IMR), Bergen, Norway
| | - Nils Chr Stenseth
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Coastal Research (CCR), Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - Øystein Langangen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
- Section for Aquatic Biology and Toxicology (AQUA), Department of Biosciences, University of Oslo, Oslo, Norway
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7
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A spatial regime shift from predator to prey dominance in a large coastal ecosystem. Commun Biol 2020; 3:459. [PMID: 32855431 PMCID: PMC7452892 DOI: 10.1038/s42003-020-01180-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 07/23/2020] [Indexed: 11/24/2022] Open
Abstract
Regime shifts in ecosystem structure and processes are typically studied from a temporal perspective. Yet, theory predicts that in large ecosystems with environmental gradients, shifts should start locally and gradually spread through space. Here we empirically document a spatially propagating shift in the trophic structure of a large aquatic ecosystem, from dominance of large predatory fish (perch, pike) to the small prey fish, the three-spined stickleback. Fish surveys in 486 shallow bays along the 1200 km western Baltic Sea coast during 1979–2017 show that the shift started in wave-exposed archipelago areas near the open sea, but gradually spread towards the wave-sheltered mainland coast. Ecosystem surveys in 32 bays in 2014 show that stickleback predation on juvenile predators (predator–prey reversal) generates a feedback mechanism that appears to reinforce the shift. In summary, managers must account for spatial heterogeneity and dispersal to better predict, detect and confront regime shifts within large ecosystems. Eklöf et al. report a spatially propagating shift in the trophic structure along the western Baltic Sea coast. The authors use fish surveys from 1979–2017 to show a shift from dominance of large predatory fish to the small prey fish, the three-spined stickleback, starting in wave-exposed areas and gradually moving to the wave-sheltered coast.
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8
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Sguotti C, Otto SA, Frelat R, Langbehn TJ, Ryberg MP, Lindegren M, Durant JM, Chr Stenseth N, Möllmann C. Catastrophic dynamics limit Atlantic cod recovery. Proc Biol Sci 2020; 286:20182877. [PMID: 30862289 PMCID: PMC6458326 DOI: 10.1098/rspb.2018.2877] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Collapses and regime changes are pervasive in complex systems (such as marine ecosystems) governed by multiple stressors. The demise of Atlantic cod (Gadus morhua) stocks constitutes a text book example of the consequences of overexploiting marine living resources, yet the drivers of these nearly synchronous collapses are still debated. Moreover, it is still unclear why rebuilding of collapsed fish stocks such as cod is often slow or absent. Here, we apply the stochastic cusp model, based on catastrophe theory, and show that collapse and recovery of cod stocks are potentially driven by the specific interaction between exploitation pressure and environmental drivers. Our statistical modelling study demonstrates that for most of the cod stocks, ocean warming could induce a nonlinear discontinuous relationship between fishing pressure and stock size, which would explain hysteresis in their response to reduced exploitation pressure. Our study suggests further that a continuing increase in ocean temperatures will probably limit productivity and hence future fishing opportunities for most cod stocks of the Atlantic Ocean. Moreover, our study contributes to the ongoing discussion on the importance of climate and fishing effects on commercially exploited fish stocks, highlighting the importance of considering discontinuous dynamics in holistic ecosystem-based management approaches, particularly under climate change.
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Affiliation(s)
- Camilla Sguotti
- 1 Institute for Marine Ecosystem and Fisheries Science (IMF), Center for Earth System Research and Sustainability (CEN), University of Hamburg , 22767 Hamburg , Germany
| | - Saskia A Otto
- 1 Institute for Marine Ecosystem and Fisheries Science (IMF), Center for Earth System Research and Sustainability (CEN), University of Hamburg , 22767 Hamburg , Germany
| | - Romain Frelat
- 1 Institute for Marine Ecosystem and Fisheries Science (IMF), Center for Earth System Research and Sustainability (CEN), University of Hamburg , 22767 Hamburg , Germany
| | - Tom J Langbehn
- 2 Department of Biological Sciences, University of Bergen , 5006 Bergen , Norway
| | - Marie Plambech Ryberg
- 3 National Institute of Aquatic Resources, Technical University of Denmark (DTU Aqua) , 2800 Kgs Lyngby , Denmark
| | - Martin Lindegren
- 3 National Institute of Aquatic Resources, Technical University of Denmark (DTU Aqua) , 2800 Kgs Lyngby , Denmark
| | - Joël M Durant
- 4 Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo , 0316 Oslo , Norway
| | - Nils Chr Stenseth
- 4 Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo , 0316 Oslo , Norway
| | - Christian Möllmann
- 1 Institute for Marine Ecosystem and Fisheries Science (IMF), Center for Earth System Research and Sustainability (CEN), University of Hamburg , 22767 Hamburg , Germany
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9
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Nilsson J, Flink H, Tibblin P. Predator-prey role reversal may impair the recovery of declining pike populations. J Anim Ecol 2019; 88:927-939. [PMID: 30895606 DOI: 10.1111/1365-2656.12981] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/02/2019] [Indexed: 11/26/2022]
Abstract
Many fish populations have experienced declines in recent decades due to anthropogenic disturbances, such as overfishing and habitat exploitation. Despite management actions, many populations show a limited capacity to recover. This may be attributed to reversal of predator-prey roles, yet empirical evidence to that effect remains scarce. Here, we combine field and laboratory studies to investigate the interaction between pike (Esox lucius), a large keystone top predatory fish, and the small-bodied mesopredatory threespine stickleback (Gasterosteus aculeatus) in the Baltic Sea where pike populations have declined. Our data suggest that stickleback predation on pike larvae depletes a large proportion of the recruitment and influences the size distribution through size-selective predation, which is corroborated by a gape-limitation experiment and diet analysis of wild-captured sticklebacks. The effects of stickleback predation are present across several populations and years, and our data suggest that early arrival of sticklebacks has stronger effects on juvenile pike survival. Finally, we use data on pike gape-limitation and the size distribution of sticklebacks to illustrate the process of role reversal. These findings suggest that mesopredator behaviour can reduce recruitment of a top predator species and impair the capacity of populations to recover. This emphasizes predator-prey role reversal as an important ecological and evolutionary driver that influences the outcome of restoration and management actions.
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Affiliation(s)
- Jonas Nilsson
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Henrik Flink
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Petter Tibblin
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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Ratajczak Z, D'Odorico P, Collins SL, Bestelmeyer BT, Isbell FI, Nippert JB. The interactive effects of press/pulse intensity and duration on regime shifts at multiple scales. ECOL MONOGR 2017. [DOI: 10.1002/ecm.1249] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Zak Ratajczak
- Environmental Science University of Virginia Clark Hall Charlottesville Virginia 29903 USA
| | - Paolo D'Odorico
- Environmental Science University of Virginia Clark Hall Charlottesville Virginia 29903 USA
- National Socio‐Environmental Synthesis Center University of Maryland Annapolis Maryland 21401 USA
- Department of Environmental Science Policy and Management University of California Berkeley Berkeley California 94720 USA
| | - Scott L. Collins
- Department of Biology University of New Mexico Albuquerque New Mexico 87131 USA
| | - Brandon T. Bestelmeyer
- USDA‐ARS Jornada Experimental Range and Jornada Basin LTER New Mexico State University Las Cruces New Mexico 88003 USA
| | - Forest I. Isbell
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul Minnesota 55108 USA
| | - Jesse B. Nippert
- Division of Biology Kansas State University Manhattan Kansas 66506 USA
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12
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Kriegisch N, Reeves S, Johnson CR, Ling SD. Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs. PLoS One 2016; 11:e0168333. [PMID: 28030596 PMCID: PMC5193397 DOI: 10.1371/journal.pone.0168333] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/09/2016] [Indexed: 12/05/2022] Open
Abstract
Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) was manipulated over 12 months to estimate (1) the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2) the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia. In parallel, the role of one of the 'bottom-up' drivers of ecosystem structure was examined by (3) manipulating local nutrient levels and thus attempting to alter primary production on the experimental reefs. It was found that densities of 8 or more urchins m-2 (≥ 427 g m-2 biomass) lead to complete overgrazing of kelp beds while kelp bed recovery occurred when densities were reduced to ≤ 4 urchins m-2 (≤ 213 g m-2 biomass). This experiment provided further insight into the dynamics of transition between urchin barrens and kelp beds by exploring possible tipping-points which in this system can be found between 4 and 8 urchins m-2 (213 and 427 g m-2 respectively). Local enhancement of nutrient loading did not change the urchin density required for overgrazing or kelp bed recovery, as algal growth was not affected by nutrient enhancement.
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Affiliation(s)
- Nina Kriegisch
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
| | - Simon Reeves
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
| | - Craig R. Johnson
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
| | - Scott D. Ling
- Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Tasmania, Australia
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Papworth DJ, Marini S, Conversi A. A Novel, Unbiased Analysis Approach for Investigating Population Dynamics: A Case Study on Calanus finmarchicus and Its Decline in the North Sea. PLoS One 2016; 11:e0158230. [PMID: 27366910 PMCID: PMC4930201 DOI: 10.1371/journal.pone.0158230] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/13/2016] [Indexed: 11/25/2022] Open
Abstract
Marine populations are controlled by a series of drivers, pertaining to both the physical environment and the biological environment (trophic predator-prey interactions). There is heated debate over drivers, especially when trying to understand the causes of major ecosystem events termed regime shifts. In this work, we have researched and developed a novel methodology based on Genetic Programming (GP) for distinguishing which drivers can influence species abundance. This methodology benefits of having no a priori assumptions either on the ecological parameters used or on the underlying mathematical relationships among them. We have validated this methodology applying it to the North Sea pelagic ecosystem. We use the target species Calanus finmarchicus, a key copepod in temperate and subarctic ecosystems, along with 86 biological, hydrographical and climatic time series, ranging from local water nutrients and fish predation, to large scale climate pressure patterns. The chosen study area is the central North Sea, from 1972 to 2011, during which period there was an ecological regime shift. The GP based analysis identified 3 likely drivers of C. finmarchicus abundance, which highlights the importance of considering both physical and trophic drivers: temperature, North Sea circulation (net flow into the North Atlantic), and predation (herring). No large scale climate patterns were selected, suggesting that when there is availability of both data types, local drivers are more important. The results produced by the GP based procedure are consistent with the literature published to date, and validate the use of GP for interpreting species dynamics. We propose that this methodology holds promises for the highly non-linear field of ecology.
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Affiliation(s)
- Danny J. Papworth
- Faculty of Science and Technology, School of Marine Science and Engineering, Plymouth University, Plymouth, Devon, PL4 8AA, United Kingdom
| | - Simone Marini
- ISMAR–Marine Sciences Institute in La Spezia, CNR–National Research Council of Italy, Forte Santa Teresa, Loc. Pozzuolo, 19032, Lerici, SP, Italy
| | - Alessandra Conversi
- ISMAR–Marine Sciences Institute in La Spezia, CNR–National Research Council of Italy, Forte Santa Teresa, Loc. Pozzuolo, 19032, Lerici, SP, Italy
- Marine Institute, Plymouth University, Plymouth, Devon, PL4 8AA, United Kingdom
- * E-mail:
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Renneville C, Rouzic AL, Baylac M, Millot A, Loisel S, Edeline E. Morphological drivers of trophic cascades. OIKOS 2015. [DOI: 10.1111/oik.02877] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Clémentine Renneville
- CNRS/Sorbonne Universités/UPMC Univ Paris 06/INRA/IRD/Paris Diderot Univ. Paris 07/UPEC/Inst. d'Ecologie et des Sciences de l'Environnement- Paris (iEES-Paris); 7 quai St Bernard FR-75252 Paris France
| | - Arnaud Le Rouzic
- CNRS/Univ. Paris-Sud/IRD/Univ. Paris-Saclay/Evolution, Génomes, Comportement, Ecologie (EGCE); Avenue de la Terrasse FR-91198 Gif-sur-Yvette France
| | - Michel Baylac
- MNHN/CNRS/UPMC Univ. Paris 06/EPHE/Inst. de Systématique, Evolution, Biodiversité (ISYEB); 45 rue Buffon FR-75005 Paris France
- MNHN/CNRS/Outils et Méthodes de la Systématique Integrative (OMSI); 45 rue Buffon FR-75005 Paris France
| | - Alexis Millot
- ENS/CNRS/CEREEP Ecotron Île-de-France; 78 rue du Château FR-77140 Saint Pierre-lès-Nemours France
| | - Stéphane Loisel
- Sorbonne Universités/UPMC Univ Paris 06/CNRS/INRA/IRD/Paris Diderot Univ Paris 07/UPEC/Inst. d'Ecologie et des Sciences de l'Environnement - Paris (iEES-Paris); 7 quai St Bernard FR-75252 Paris France
| | - Eric Edeline
- CNRS/Sorbonne Universités/UPMC Univ Paris 06/INRA/IRD/Paris Diderot Univ. Paris 07/UPEC/Inst. d'Ecologie et des Sciences de l'Environnement- Paris (iEES-Paris); 7 quai St Bernard FR-75252 Paris France
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15
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Fuiman LA, Connelly TL, Lowerre-Barbieri SK, McClelland JW. Egg boons: central components of marine fatty acid food webs. Ecology 2015; 96:362-72. [PMID: 26240858 DOI: 10.1890/14-0571.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Food web relationships are traditionally defined in terms of the flow of key elements, such as carbon, nitrogen, and phosphorus, and their role in limiting production. There is growing recognition that availability of important biomolecules, such as fatty acids, may exert controls on secondary production that are not easily explained by traditional element-oriented models. Essential fatty acids (EFAs) are required by most organisms for proper physiological function but are manufactured almost entirely by primary producers. Therefore, the flow of EFAs, especially docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA), through aquatic food webs is critical for ecosystem functioning. A meta-analysis of data on the EFA content of marine organisms reveals that individual eggs of marine animals have exceptionally high concentrations of EFAs, and that superabundances of eggs released in temporally and spatially discrete patches create rich, but temporary, nutritional resources for egg predators, called "egg boons." Mortality rates of fish eggs are disproportionately higher than animals of similar size, and those eggs are consumed by predators, both larger and smaller than the adults that produce the eggs. Thus, egg boons are a major trophic pathway through which EFAs are repackaged and redistributed, and they are among the few pathways that run counter to the main direction of trophic flow. Egg boons can transport EFAs across ecosystems through advection of patches of eggs and spawning migrations of adults. Recognizing the significance of egg boons to aquatic food webs reveals linkages and feedbacks between organisms and environments that have important implications for understanding how food webs vary in time and space. Examples are given of top-down, bottom-up, and lateral control mechanisms that could significantly alter food webs through their effects on eggs. Our results suggest that trophodynamic food web models should include EFAs generally, and egg production and egg EFA content in particular.
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Byström P, Bergström U, Hjälten A, Ståhl S, Jonsson D, Olsson J. Declining coastal piscivore populations in the Baltic Sea: Where and when do sticklebacks matter? AMBIO 2015; 44 Suppl 3:462-471. [PMID: 26022328 PMCID: PMC4447698 DOI: 10.1007/s13280-015-0665-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Intraguild predation interactions make fish communities prone to exhibit alternative stable states with either piscivore or prey fish dominance. In the Baltic Sea, local declines of coastal piscivores like perch (Perca fluviatilis) have been observed to coincide with high densities of sticklebacks (Gasterosteus aculeatus). Mechanisms behind this shift between piscivore and stickleback dominance were studied both experimentally and in field. Results showed that predation by sticklebacks has a strong negative effect on perch larvae survival, but this effect rapidly decreases with increasing perch size, likely due to gape limitations and digestion constraints in sticklebacks. Large spatial and temporal variations in patterns of stickleback migration into perch spawning sites were observed. Whether or not high density of sticklebacks will cause declines in coastal piscivore populations is suggested to depend on the availability of spawning sites in which sticklebacks do not migrate into or arrive late in the reproduction season of coastal piscivores.
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Affiliation(s)
- Pär Byström
- />Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden
| | - Ulf Bergström
- />Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Skolgatan 6, 742 42 Öregrund, Sweden
| | - Alexander Hjälten
- />Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden
| | - Sofie Ståhl
- />Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden
| | - David Jonsson
- />County Administrative Board of Västernorrland, 871 86 Härnösand, Sweden
| | - Jens Olsson
- />Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Skolgatan 6, 742 42 Öregrund, Sweden
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Gårdmark A, Casini M, Huss M, van Leeuwen A, Hjelm J, Persson L, de Roos AM. Regime shifts in exploited marine food webs: detecting mechanisms underlying alternative stable states using size-structured community dynamics theory. Philos Trans R Soc Lond B Biol Sci 2015; 370:20130262. [PMCID: PMC4247399 DOI: 10.1098/rstb.2013.0262] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
Many marine ecosystems have undergone ‘regime shifts’, i.e. abrupt reorganizations across trophic levels. Establishing whether these constitute shifts between alternative stable states is of key importance for the prospects of ecosystem recovery and for management. We show how mechanisms underlying alternative stable states caused by predator–prey interactions can be revealed in field data, using analyses guided by theory on size-structured community dynamics. This is done by combining data on individual performance (such as growth and fecundity) with information on population size and prey availability. We use Atlantic cod (Gadus morhua) and their prey in the Baltic Sea as an example to discuss and distinguish two types of mechanisms, ‘cultivation-depensation’ and ‘overcompensation’, that can cause alternative stable states preventing the recovery of overexploited piscivorous fish populations. Importantly, the type of mechanism can be inferred already from changes in the predators' body growth in different life stages. Our approach can thus be readily applied to monitored stocks of piscivorous fish species, for which this information often can be assembled. Using this tool can help resolve the causes of catastrophic collapses in marine predatory–prey systems and guide fisheries managers on how to successfully restore collapsed piscivorous fish stocks.
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Affiliation(s)
- Anna Gårdmark
- Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Skolgatan 6, Öregrund 742 42, Sweden
| | - Michele Casini
- Department of Aquatic Resources, Institute of Marine Research, Swedish University of Agricultural Sciences, Turistgatan 5, Lysekil 453 30, Sweden
| | - Magnus Huss
- Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Skolgatan 6, Öregrund 742 42, Sweden
| | - Anieke van Leeuwen
- Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Hall, Princeton, NJ 8544–2016, USA
| | - Joakim Hjelm
- Department of Aquatic Resources, Institute of Marine Research, Swedish University of Agricultural Sciences, Turistgatan 5, Lysekil 453 30, Sweden
| | - Lennart Persson
- Department of Ecology and Environmental Sciences, Umeå University, Umeå 901 87, Sweden
| | - André M. de Roos
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, Amsterdam 1090 GE, The Netherlands
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Conversi A, Dakos V, Gårdmark A, Ling S, Folke C, Mumby PJ, Greene C, Edwards M, Blenckner T, Casini M, Pershing A, Möllmann C. A holistic view of marine regime shifts. Philos Trans R Soc Lond B Biol Sci 2015; 370:20130279. [PMCID: PMC4247413 DOI: 10.1098/rstb.2013.0279] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
Understanding marine regime shifts is important not only for ecology but also for developing marine management that assures the provision of ecosystem services to humanity. While regime shift theory is well developed, there is still no common understanding on drivers, mechanisms and characteristic of abrupt changes in real marine ecosystems. Based on contributions to the present theme issue, we highlight some general issues that need to be overcome for developing a more comprehensive understanding of marine ecosystem regime shifts. We find a great divide between benthic reef and pelagic ocean systems in how regime shift theory is linked to observed abrupt changes. Furthermore, we suggest that the long-lasting discussion on the prevalence of top-down trophic or bottom-up physical drivers in inducing regime shifts may be overcome by taking into consideration the synergistic interactions of multiple stressors, and the special characteristics of different ecosystem types. We present a framework for the holistic investigation of marine regime shifts that considers multiple exogenous drivers that interact with endogenous mechanisms to cause abrupt, catastrophic change. This framework takes into account the time-delayed synergies of these stressors, which erode the resilience of the ecosystem and eventually enable the crossing of ecological thresholds. Finally, considering that increased pressures in the marine environment are predicted by the current climate change assessments, in order to avoid major losses of ecosystem services, we suggest that marine management approaches should incorporate knowledge on environmental thresholds and develop tools that consider regime shift dynamics and characteristics. This grand challenge can only be achieved through a holistic view of marine ecosystem dynamics as evidenced by this theme issue.
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Affiliation(s)
- Alessandra Conversi
- Institute of Marine Sciences, National Research Council of Italy, Forte Santa Teresa, Loc Pozzuolo, Lerici, La Spezia 19032, Italy
- Centre for Marine and Coastal Policy, Marine Institute, Plymouth University, Plymouth PL4 8AA, UK
- SAHFOS, The Laboratory, Citadel Hill, The Hoe, Plymouth PL1 2PB, UK
| | - Vasilis Dakos
- Integrative Ecology Group, Estación Biológica de Doñana (CSIC), Américo Vespucio s/n, Sevilla 41092, Spain
| | - Anna Gårdmark
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Institute of Coastal Research, Skolgatan 6, Öregrund 742 42, Sweden
| | - Scott Ling
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, HOBART TAS 7001, Tasmania
| | - Carl Folke
- Beijer Institute, Royal Swedish Academy of Sciences, PO Box 50005, Stockholm 104 05, Sweden
- Stockholm Resilience Centre, Stockholm University, Kräftriket 2B, Stockholm 106 91, Sweden
| | - Peter J. Mumby
- Marine Spatial Ecology Lab, School of Biological Sciences and ARC Centre of Excellence for Coral Reef Studies, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Charles Greene
- Ocean Resources and Ecosystems Program, Cornell University, Ithaca, New York, NY, USA
| | - Martin Edwards
- SAHFOS, The Laboratory, Citadel Hill, The Hoe, Plymouth PL1 2PB, UK
| | - Thorsten Blenckner
- Stockholm Resilience Centre, Stockholm University, Kräftriket 2B, Stockholm 106 91, Sweden
| | - Michele Casini
- Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Turistgatan 5, Lysekil 45330, Sweden
| | - Andrew Pershing
- Gulf of Maine Research Institute, 350 Commercial Street, Portland, ME 04101, USA
| | - Christian Möllmann
- Institute for Hydrobiology and Fisheries Science, University of Hamburg, Grosse Elbstrasse 133, Hamburg 22767, Germany
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Fisher JAD, Casini M, Frank KT, Möllmann C, Leggett WC, Daskalov G. The importance of within-system spatial variation in drivers of marine ecosystem regime shifts. Philos Trans R Soc Lond B Biol Sci 2015; 370:20130271. [PMCID: PMC4247406 DOI: 10.1098/rstb.2013.0271] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
Comparative analyses of the dynamics of exploited marine ecosystems have led to differing hypotheses regarding the primary causes of observed regime shifts, while many ecosystems have apparently not undergone regime shifts. These varied responses may be partly explained by the decade-old recognition that within-system spatial heterogeneity in key climate and anthropogenic drivers may be important, as recent theoretical examinations have concluded that spatial heterogeneity in environmental characteristics may diminish the tendency for regime shifts. Here, we synthesize recent, empirical within-system spatio-temporal analyses of some temperate and subarctic large marine ecosystems in which regime shifts have (and have not) occurred. Examples from the Baltic Sea, Black Sea, Bengula Current, North Sea, Barents Sea and Eastern Scotian Shelf reveal the largely neglected importance of considering spatial variability in key biotic and abiotic influences and species movements in the context of evaluating and predicting regime shifts. We highlight both the importance of understanding the scale-dependent spatial dynamics of climate influences and key predator–prey interactions to unravel the dynamics of regime shifts, and the utility of spatial downscaling of proposed mechanisms (as evident in the North Sea and Barents Sea) as a means of evaluating hypotheses originally derived from among-system comparisons.
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Affiliation(s)
- J. A. D. Fisher
- Centre for Fisheries Ecosystems Research, Fisheries and Marine Institute of Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, CanadaA1C 5R3
| | - M. Casini
- Department of Aquatic Resources, Institute of Marine Research, Swedish University of Agricultural Sciences, Lysekil 54330, Sweden
| | - K. T. Frank
- Ocean Sciences Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, CanadaB2Y 4A2
| | - C. Möllmann
- Institute of Hydrobiology and Fisheries Sciences, University of Hamburg, Hamburg 22767, Germany
| | - W. C. Leggett
- Department of Biology, Queen's University, Kingston, Ontario, CanadaK7L 3N6
| | - G. Daskalov
- Department of Aquatic Ecosystems, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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Sánchez-Garduño F, Miramontes P, Marquez-Lago TT. Role reversal in a predator-prey interaction. ROYAL SOCIETY OPEN SCIENCE 2014; 1:140186. [PMID: 26064541 PMCID: PMC4448886 DOI: 10.1098/rsos.140186] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/27/2014] [Indexed: 06/04/2023]
Abstract
Predator-prey relationships are one of the most studied interactions in population ecology. However, little attention has been paid to the possibility of role exchange between species, despite firm field evidence of such phenomena in nature. In this paper, we build a mathematical model capable of reproducing the main phenomenological features of role reversal in a classical system and present results for both the temporal and spatio-temporal cases. We show that, depending on the choice of parameters, our role-reversal dynamical system exhibits excitable-like behaviour, generating waves of species' concentrations that propagate through space. Our findings fill a long-standing gap in modelling ecological interactions and can be applicable to better understanding ecological niche shifts and planning of sustainable ecosystems.
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Affiliation(s)
| | - Pedro Miramontes
- Facultad de Ciencias, Universidad Nacional Autónoma de México, México DF., 04510, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México DF., 04510, Mexico
| | - Tatiana T Marquez-Lago
- Integrative Systems Biology Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0412, Japan
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Fraschetti S, Guarnieri G, Bevilacqua S, Terlizzi A, Boero F. Protection enhances community and habitat stability: evidence from a mediterranean marine protected area. PLoS One 2013; 8:e81838. [PMID: 24349135 PMCID: PMC3859515 DOI: 10.1371/journal.pone.0081838] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 10/27/2013] [Indexed: 12/02/2022] Open
Abstract
Rare evidences support that Marine Protected Areas (MPAs) enhance the stability of marine habitats and assemblages. Based on nine years of observation (2001–2009) inside and outside a well managed MPA, we assessed the potential of conservation and management actions to modify patterns of spatial and/or temporal variability of Posidonia oceanica meadows, the lower midlittoral and the shallow infralittoral rock assemblages. Significant differences in both temporal variations and spatial patterns were observed between protected and unprotected locations. A lower temporal variability in the protected vs. unprotected assemblages was found in the shallow infralittoral, demonstrating that, at least at local scale, protection can enhance community stability. Macrobenthos with long-lived and relatively slow-growing invertebrates and structurally complex algal forms were homogeneously distributed in space and went through little fluctuations in time. In contrast, a mosaic of disturbed patches featured unprotected locations, with small-scale shifts from macroalgal stands to barrens, and harsh temporal variations between the two states. Opposite patterns of spatial and temporal variability were found for the midlittoral assemblages. Despite an overall clear pattern of seagrass regression through time, protected meadows showed a significantly higher shoot density than unprotected ones, suggesting a higher resistance to local human activities. Our results support the assumption that the exclusion/management of human activities within MPAs enhance the stability of the structural components of protected marine systems, reverting or arresting threat-induced trajectories of change.
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Affiliation(s)
- Simonetta Fraschetti
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Consorzio Nazionale Interuniversitario per le Scienze del Mare, Lecce, Italy
- * E-mail:
| | - Giuseppe Guarnieri
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Consorzio Nazionale Interuniversitario per le Scienze del Mare, Lecce, Italy
| | - Stanislao Bevilacqua
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Consorzio Nazionale Interuniversitario per le Scienze del Mare, Lecce, Italy
| | - Antonio Terlizzi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Consorzio Nazionale Interuniversitario per le Scienze del Mare, Lecce, Italy
| | - Ferdinando Boero
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Consorzio Nazionale Interuniversitario per le Scienze del Mare, Lecce, Italy
- Institute of Marine Sciences of National Research Council, Genova, Italy
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Houle JE, Andersen KH, Farnsworth KD, Reid DG. Emerging asymmetric interactions between forage and predator fisheries impose management trade-offs. JOURNAL OF FISH BIOLOGY 2013; 83:890-904. [PMID: 24090553 DOI: 10.1111/jfb.12163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 04/29/2013] [Indexed: 06/02/2023]
Abstract
A size and trait-based marine community model was used to investigate interactions, with potential implications for yields, when a fishery targeting forage fish species (whose main adult diet is zooplankton) co-occurs with a fishery targeting larger-sized predator species. Predicted effects on the size structure of the fish community, growth and recruitment of fishes, and yield from the fisheries were used to identify management trade-offs among the different fisheries. Results showed that moderate fishing on forage fishes imposed only small effects on predator fisheries, whereas predator fisheries could enhance yield from forage fisheries under some circumstances.
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Affiliation(s)
- J E Houle
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, U.K
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van Denderen PD, van Kooten T. Size-based species interactions shape herring and cod population dynamics in the face of exploitation. Ecosphere 2013. [DOI: 10.1890/es13-00164.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Fraser DF, Lamphere BA. Experimental evaluation of predation as a facilitator of invasion success in a stream fish. Ecology 2013; 94:640-9. [DOI: 10.1890/12-0803.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Nyström M, Norström AV, Blenckner T, de la Torre-Castro M, Eklöf JS, Folke C, Österblom H, Steneck RS, Thyresson M, Troell M. Confronting Feedbacks of Degraded Marine Ecosystems. Ecosystems 2012. [DOI: 10.1007/s10021-012-9530-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Role of egg predation by haddock in the decline of an Atlantic herring population. Proc Natl Acad Sci U S A 2011; 108:13606-11. [PMID: 21825166 DOI: 10.1073/pnas.1015400108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Theoretical studies suggest that the abrupt and substantial changes in the productivity of some fisheries species may be explained by predation-driven alternate stable states in their population levels. With this hypothesis, an increase in fishing or a natural perturbation can drive a population from an upper to a lower stable-equilibrium population level. After fishing is reduced or the perturbation ended, this low population level can persist due to the regulatory effect of the predator. Although established in theoretical studies, there is limited empirical support for predation-driven alternate stable states in exploited marine fish populations. We present evidence that egg predation by haddock (Melanogrammus aeglefinus) can cause alternate stable population levels in Georges Bank Atlantic herring (Clupea harengus). Egg predation by haddock explains a substantial decoupling of herring spawning stock biomass (an index of egg production) from observed larval herring abundance (an index of egg hatching). Estimated egg survival rates ranged from <2-70% from 1971 to 2005. A population model incorporating egg predation and herring fishing explains the major population trends of Georges Bank herring over four decades and predicts that, when the haddock population is high, seemingly conservative levels of fishing can still precipitate a severe decline in the herring population. These findings illustrate how efforts to rebuild fisheries can be undermined by not incorporating ecological interactions into fisheries models and management plans.
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Fauchald P, Skov H, Skern-Mauritzen M, Johns D, Tveraa T. Wasp-waist interactions in the North Sea ecosystem. PLoS One 2011; 6:e22729. [PMID: 21829494 PMCID: PMC3145753 DOI: 10.1371/journal.pone.0022729] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 06/29/2011] [Indexed: 11/28/2022] Open
Abstract
Background In a “wasp-waist” ecosystem, an intermediate trophic level is expected to control the abundance of predators through a bottom-up interaction and the abundance of prey through a top-down interaction. Previous studies suggest that the North Sea is mainly governed by bottom-up interactions driven by climate perturbations. However, few studies have investigated the importance of the intermediate trophic level occupied by small pelagic fishes. Methodology/Principal Findings We investigated the numeric interactions among 10 species of seabirds, two species of pelagic fish and four groups of zooplankton in the North Sea using decadal-scale databases. Linear models were used to relate the time series of zooplankton and seabirds to the time series of pelagic fish. Seabirds were positively related to herring (Clupea harengus), suggesting a bottom-up interaction. Two groups of zooplankton; Calanus helgolandicus and krill were negatively related to sprat (Sprattus sprattus) and herring respectively, suggesting top-down interactions. In addition, we found positive relationships among the zooplankton groups. Para/pseudocalanus was positively related to C. helgolandicus and C. finmarchicus was positively related to krill. Conclusion/Significance Our results indicate that herring was important in regulating the abundance of seabirds through a bottom-up interaction and that herring and sprat were important in regulating zooplankton through top-down interactions. We suggest that the positive relationships among zooplankton groups were due to selective foraging and switching in the two clupeid fishes. Our results suggest that “wasp-waist” interactions might be more important in the North Sea than previously anticipated. Fluctuations in the populations of pelagic fish due to harvesting and depletion of their predators might accordingly have profound consequences for ecosystem dynamics through trophic cascades.
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Affiliation(s)
- Per Fauchald
- Department of Arctic Ecology, Norwegian Institute for Nature Research (NINA), Fram Centre, Tromsø, Norway.
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31
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Frank KT, Petrie B, Fisher JAD, Leggett WC. Transient dynamics of an altered large marine ecosystem. Nature 2011; 477:86-9. [DOI: 10.1038/nature10285] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 06/13/2011] [Indexed: 11/09/2022]
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