8 Resource and ecosystem variability, including regime shifts, in the Benguela Current System

Lingen, Carl D. van der; Shannon, Lynne J.; Cury, Philippe; Kreiner, Anja; Moloney, Coleen L.; Roux, Jean‐Paul; Vaz-Velho, Filomena

doi:10.1016/s1570-0461(06)80013-3

Cited by 108 publications

(72 citation statements)

References 85 publications

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“…Future research should aim to identify and quantify which combination of factors is most crucial for the recovery of depleted populations and degraded ecosystems to make conservation and management strategies most cost effective. Future studies should also address how regime shifts and alternative stable states affect recovery prospects [18,86]. Moreover, identifying historical reference points and carrying capacity for individual populations and ecosystems is key for setting conservation and management targets.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, a deep seagrass meadow showed only a few signs of recovery 100 years after trawling [75], and a megabenthic seamount assemblage failed to recover 5-10 years after trawling [76]. Population or ecosystem recovery might take even longer if there has been a regime shift, as in the Benguela ecosystem [18].…”

Section: Magnitude Of Recoverymentioning

confidence: 99%

“…Similarly, many coastal habitats, including wetlands, seagrass beds, mangrove and kelp forests, and oyster and coral reefs, have been severely reduced or degraded [2][3][4]6], yet partial recovery has been achieved in some regions in response to protection and pollution controls [3,13]. Restoration attempts at an ecosystem level have often been followed by the return and recovery of former species assemblages and ecosystem functions [13][14][15][16][17], but some ecosystems have remained in an altered state [18]. Such successes could serve as important guides for efforts to prevent further biodiversity loss and enhance future recoveries.…”

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confidence: 99%

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Recovery of marine animal populations and ecosystems

Lotze¹,

Coll²,

Magera³

et al. 2011

Trends in Ecology & Evolution

358

316

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Many marine populations and ecosystems have experienced strong historical depletions, yet reports of recoveries are increasing. Here, we review the growing research on marine recoveries to reveal how common recovery is, its magnitude, timescale and major drivers. Overall, 10-50% of depleted populations and ecosystems show some recovery, but rarely to former levels of abundance. In addition, recovery can take many decades for long-lived species and complex ecosystems. Major drivers of recovery include the reduction of human impacts, especially exploitation, habitat loss and pollution, combined with favorable life-history and environmental conditions. Awareness, legal protection and enforcement of management plans are also crucial. Learning from historical recovery successes and failures is essential for implementing realistic conservation goals and promising management strategies.A new focus on recovery An increasing number of studies have reported strong declines in marine animal populations and the degradation of ocean ecosystems over past decades and centuries around the world [1][2][3][4][5][6][7], leading to a widespread perception of empty oceans and polluted waters. Yet, throughout history, humans have responded to declining resource abundance and ecosystem degradation by implementing management and conservation measures. Some of these have been successful and resulted in recovery, whereas others have failed [3,8,9].Therefore, an important question to science and management is: how common is recovery among depleted populations and degraded ecosystems in the ocean? Today, many marine mammal, bird, reptile and fish populations are at low abundance, and several species are endangered or extinct on regional or global scales [5,[10][11][12]. However, despite long periods of intense human impacts, most marine species persist and some populations do show signs of recovery [3,8,9]. Similarly, many coastal habitats, including wetlands, seagrass beds, mangrove and kelp forests, and oyster and coral reefs, have been severely reduced or degraded [2][3][4]6], yet partial recovery has been achieved in some regions in response to protection and pollution controls [3,13]. Restoration attempts at an ecosystem level have often been followed by the return and recovery of former species assemblages and ecosystem functions [13][14][15][16][17], but some ecosystems have remained in an altered state [18]. Such successes could serve as important guides for efforts to prevent further biodiversity loss and enhance future recoveries.Despite a growing number of case studies on the recovery of specific populations or ecosystems, an overview of the general patterns and drivers of marine recoveries over historical timescales is lacking. A recent review on the recovery of damaged ecosystems found that many terrestrial and marine ecosystems can recover on timescales of a few years to a few decades after major perturbations [19]. However, most case studies in the review, especially among marine and brackish examples, included small, short-...

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Section: Discussionmentioning

confidence: 99%

Section: Magnitude Of Recoverymentioning

confidence: 99%

mentioning

confidence: 99%

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Recovery of marine animal populations and ecosystems

Lotze¹,

Coll²,

Magera³

et al. 2011

Trends in Ecology & Evolution

358

316

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“…Whereas the SB (at least the west-coast portion thereof) continues to function as a "classic" upwelling ecosystem, the NB has undergone profound structural changes since the collapse of the sardine population there (Cury and Shannon 2004, Bakun and Weeks 2006, van der Lingen et al 2006) and now stands out as the only eastern boundary upwelling ecosystem with few small pelagic fishes and with a very high jellyfish biomass (see e.g., Moloney et al 2005).…”

Section: The Role Of Small Pelagic Fishes and What Canmentioning

confidence: 99%

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Roux¹,

Lingen²,

Gibbons³

et al. 2013

BMS

128

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Changes in two contrasting ecosystems of the Benguela upwelling region, one dominated at mid-trophic level by jellyfishes (Namibia, northern Benguela ecosystem, where small pelagic fish abundance has been severely depleted) and one still dominated by small pelagic fishes (South Africa, southern Benguela) were compared in an effort to determine ecosystem trajectories under different exploitation regimes. The role of small pelagic fishes (clupeoids) was highlighted in the context of their importance in maintaining interactions in marine ecosystems. In particular, we examined trophic cascades and possible irreversible changes that promote the proliferation of jellyfishes in marine systems. We found that the presence of large populations of small pelagic fishes has a fundamental role in preserving beneficial trophic interactions in these marine ecosystems. The implications of trophic cascades, such as those observed in the northern Benguela, for ecosystem-based management were apparent. In addition, this comparison provides contrasting case studies to inform the development of management scenarios that avoid ecosystem shifts that affect predators and reduce the value of fisheries production.

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“…Wallace et al 1984, Japp et al 1994, Yemane et al 2005, predator-prey interactions (e.g. Dyer 1995, Punt and and environmental effects (van der Lingen et al 2006a, Watermeyer et al 2008. Near Tsitsikamma, fishing on a temperate reef community was found to affect the size and abundance of roman Chrysoblephus laticeps (Götz et al 2009a), the dominant fish species in catches, allowing their competitors to increase and also affecting benthic communities (Götz et al 2009b).…”

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confidence: 99%

Reviewing evidence of marine ecosystem change off South Africa

Moloney

Fennessy

Gibbons

et al. 2013

African Journal of Marine Science

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Recent changes have been observed in South African marine ecosystems. The main pressures on these ecosystems are fishing, climate change, pollution, ocean acidification and mining. The best long-term datasets are for trends in fishing pressures but there are many gaps, especially for non-commercial species. Fishing pressures have varied over time, depending on the species being caught. Little information exists for trends in other anthropogenic pressures. Field observations of environmental variables are limited in time and space. Remotely sensed satellite data have improved spatial and temporal coverage but the time-series are still too short to distinguish long-term trends from interannual and decadal variability. There are indications of recent cooling on the West and South coasts and warming on the East Coast over a period of 20-30 years. Oxygen concentrations on the West Coast have decreased over this period. Observed changes in offshore marine communities include southward and eastward changes in species distributions, changes in abundance of species, and probable alterations in foodweb dynamics. Causes of observed changes are difficult to attribute. Full understanding of marine ecosystem change requires ongoing and effective data collection, management and archiving, and coordination in carrying out ecosystem research.

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8 Resource and ecosystem variability, including regime shifts, in the Benguela Current System

Cited by 108 publications

References 85 publications

Recovery of marine animal populations and ecosystems

Recovery of marine animal populations and ecosystems

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Reviewing evidence of marine ecosystem change off South Africa

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