Large-scale associations between macroalgal cover and grazer biomass on mid-depth reefs in the Caribbean

Williams, Ivor D.; Polunin, Nicholas

doi:10.1007/s003380000121

Cited by 236 publications

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“…In the Caribbean, parrotfish (Labridae, Scarinae) are the dominant herbivores on middepth (5-15 m) forereefs (9)(10)(11), helping keep large seaweeds in check and facilitating the recovery and growth of corals (12)(13)(14). However, parrotfish are an important fishery species (15), and their depletion can lead to a flip in coral population dynamics that locks reefs into a persistent degraded state (16).…”

mentioning

confidence: 99%

Tradeoffs between fisheries harvest and the resilience of coral reefs

Bozec

O’Farrell

Bruggemann

et al. 2016

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

126

114

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Many countries are legally obliged to embrace ecosystem-based approaches to fisheries management. Reductions in bycatch and physical habitat damage are now commonplace, but mitigating more sophisticated impacts associated with the ecological functions of target fisheries species are in their infancy. Here we model the impacts of a parrotfish fishery on the future state and resilience of Caribbean coral reefs, enabling us to view the tradeoff between harvest and ecosystem health. We find that the implementation of a simple and enforceable size restriction of >30 cm provides a win:win outcome in the short term, delivering both ecological and fisheries benefits and leading to increased yield and greater coral recovery rate for a given harvest rate. However, maintaining resilient coral reefs even until 2030 requires the addition of harvest limitations (<10% of virgin fishable biomass) to cope with a changing climate and induced coral disturbances, even in reefs that are relatively healthy today. Managing parrotfish is not a panacea for protecting coral reefs but can play a role in sustaining the health of reefs and highquality habitat for reef fisheries. M uch effort in ecosystem-based fishery management has been directed to reducing the detrimental impacts of fishing gear on the ecosystem, including bycatch and habitat damage (1, 2). A more complex consideration is maintaining the ecosystem function of the target species. A well-known example is the importance of forage fish and krill to the diet of large fish, sea birds, and marine mammals (3-5), which generates a tradeoff between human and nonhuman (natural) consumption of the stock. Measuring such direct trophic tradeoffs is challenging enough (6), but some ecosystem functions act through complex ecological interactions that might involve multiple trophic levels and result in nonlinear impacts on the ecosystem (7). Perhaps not surprisingly, there has been little progress in modifying fishing activity to take account of these compound ecological processes (8).The impacts of fishing are particularly severe in the most complex of marine ecosystems, coral reefs. In the Caribbean, parrotfish (Labridae, Scarinae) are the dominant herbivores on middepth (5-15 m) forereefs (9-11), helping keep large seaweeds in check and facilitating the recovery and growth of corals (12-14). However, parrotfish are an important fishery species (15), and their depletion can lead to a flip in coral population dynamics that locks reefs into a persistent degraded state (16). A shift to macroalgal dominance offers relatively little value to fisheries, because much of the primary production is lost to detrital pathways rather than fish-based consumption (17). Macroalgal dominance usually is associated with less complex coral habitats, which in turn are associated with lower biodiversity and fewer ecosystem functions (18). Although several countries [e.g., Belize, Bonaire, and Bermuda (19)] have implemented a ban on parrotfish harvest, most jurisdictions either have no fisheries restrictions ...

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mentioning

confidence: 99%

Tradeoffs between fisheries harvest and the resilience of coral reefs

Bozec

O’Farrell

Bruggemann

et al. 2016

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

126

114

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“…2004, Stockwell et al 2009). These fishes are known herbivores (Choat 1991) and play a major role in the integrity of the reef by reducing the algal growth (Mc Clanahan et al 2001;Williams and Polunin 2001;Russ 2003;Mumby et al 2006;Stockwell et al 2009) in effect promotes growth and possibly recruitment of corals (Mumby et al 2007). …”

Section: Aundanao Mpamentioning

confidence: 99%

Ecological and economic assessment of two marine protected areas in the island garden city of Samal, Davao Gulf, Philippines

Naola

Plasabas

Ballesteros

et al. 2013

Galaxea, Journal of Coral Reef Studies

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The performance of two marine protected areas (MPAs) in Samal Island, Coral Garden and Aundanao MPAs were evaluated after more than 10 years of exis tence. The evaluation tools used were fishery dependent (i.e. focus group discussion) and independent (i.e. fish census, benthic assessment and crown of thorns density) samplings. All sampling was conducted at least twice for one year. In all sites, COTs densities were just above the alarming stage (~1 individual.250 m −2 ). Aundanao MPA showed a positive feedback system by supporting the spillover effect. There is high density of sexually mature fish (＜30 cm Total length and significantly higher fish biomass estimates of target species (16 mt km −2 ) inside than outside the MPA. The relatively small catch (20 mt year −1 ) from fishing adjacent to the MPA is attributed to the limited capacity of the core zone (only 3 ha) to support the fishery. It also serves as a refuge site for small pelagic fishes (i.e. ox-eye scad, Selar boops) that aggregate along the slope. In contrast, the Coral Garden MPA had very low fish biomass (4.0 mt km −2 ) and only a couple of sexually mature individuals both inside and outside the sites.Intermittent guarding which have resulted to occasional poaching in the no take area was one of the reasons.

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“…One mechanism that can theoretically drive alternative stable states is a positive association between coral cover and grazing rates on macroalgae that would otherwise overgrow corals (Mumby et al 2007). Empirical evidence supports the potential for corals to attract grazers that would otherwise avoid macroalgal-dominated patches (Williams and Polunin 2001;Hoey and Bellwood 2011), macroalgal overgrowth of corals in the absence of grazers (Hughes et al 2007), and macroalgae prevention of coral recruitment (McCook et al 2001); corals also compete directly with one another via injuries to soft tissue and overtopping (Lang and Chornesky 1990). Under this mechanism, competing corals experience indirect facilitation through negative effects on a shared noncoral competitor.…”

Section: Introductionmentioning

confidence: 99%

Response Diversity Can Increase Ecological Resilience to Disturbance in Coral Reefs

Baskett

Fabina

Gross

2014

The American Naturalist

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Community-level resilience depends on the interaction between multiple populations that vary in individual responses to disturbance. For example, in tropical reefs, some corals can survive higher stress (resistance) while others exhibit faster recovery (engineering resilience) following disturbances such as thermal stress. While each type will negatively affect the other through competition, each might also benefit the other by reducing the potential for an additional competitor such as macroalgae to invade after a disturbance. To determine how community composition affects ecological resilience, we modeled coral-macroalgae interactions given either a resistant coral, a resilient coral, or both together. Having both coral types (i.e., response diversity) can lead to observable enhanced ecological resilience if (1) the resilient coral is not a superior competitor and (2) disturbance levels are high enough such that the resilient coral would collapse when considered alone. This enhanced resilience occurs through competitor-enabled rescue where each coral increases the potential for the other to recover from disturbance through external recruitment, such that both corals benefit from the presence of each other in terms of total cover and resilience. Therefore, conservation management aimed at protecting resilience under global change requires consideration of both diversity and connectivity between sites experiencing differential disturbance.

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Large-scale associations between macroalgal cover and grazer biomass on mid-depth reefs in the Caribbean

Cited by 236 publications

References 0 publications

Tradeoffs between fisheries harvest and the resilience of coral reefs

Tradeoffs between fisheries harvest and the resilience of coral reefs

Ecological and economic assessment of two marine protected areas in the island garden city of Samal, Davao Gulf, Philippines

Response Diversity Can Increase Ecological Resilience to Disturbance in Coral Reefs

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