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Russell C Babcock - One of the best experts on this subject based on the ideXlab platform.
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rapid recolonisation of snapper pagrus auratus sparidae within an offshore island Marine Reserve after implementation of no take status
Marine Ecology Progress Series, 2004Co-Authors: Christopher M Denny, Trevor J Willis, Russell C BabcockAbstract:This study reports the response of snapper Pagrus auratus to the establishment of no- take status in a Marine Reserve around the Poor Knights Islands in northeastern New Zealand. The Poor Knights and 2 reference locations, Cape Brett and the Mokohinau Islands, were sampled bi- annually for 4 yr using baited underwater video (BUV). Following the implementation of full Marine Reserve status at the Poor Knights in October 1998, snapper showed significant increases in abun- dance and biomass relative to fished control locations. This was particularly apparent for large snap- per (>270 mm), whose numbers increased rapidly to levels 7.4 times higher in the final survey com- pared to the initial pre-Reserve survey, and total snapper biomass increased by 818%. There was no significant increase in the abundance, biomass or size of snapper at the reference locations over this time. There was a strong seasonal trend in snapper abundance, with higher numbers in autumn (March/April) compared to spring (September/October). The daily batch fecundity was 11 to 18 times higher at the Poor Knights compared to the reference locations. Once fishing ceased in previously partially protected areas, a rapid recovery of snapper ensued, suggesting that partial fishing regula- tions are ineffective for protecting targeted species. The speed of increase in snapper density resulted from the immigration of adult fish into the Reserve, rather than from within-Reserve recruitment.
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ultrasonic tracking reveals multiple behavioural modes of snapper pagrus auratus in a temperate no take Marine Reserve
Ices Journal of Marine Science, 2004Co-Authors: Daniel Egli, Russell C BabcockAbstract:Interactions between Marine Reserve populations and non-Reserve populations of exploited fishes have generally been modelled using simplistic assumptions about behaviour. Consequently, there is a recognized need for better information on fish movement behaviour at the appropriate spatial scales to generate more realistic interaction models. Automated ultrasonic tracking of Marine fish, applied in this study, offers the potential to continuously track individuals for periods of up to several years within the study area. Snapper (Pagrus auratus) (FL: 33-68 cm) were surgically implanted with individually coded ultrasonic transmitters to monitor their movement within the Cape Rodney to Okakari Point Marine Reserve in northeast New Zealand from October 2001 to September 2002. The range of movement patterns observed includes some fish resident for the entire tracking period, while others were more mobile. Of the latter group, some fish left the array permanently while others returned after up to 83 days of continuous absence. Nearly all fish showed some level of site fidelity for varying periods of the time they were tracked. Fish activity peaked in the summer, when highest densities are known to occur. Results suggest that snapper behaviour is variable, and that patterns of habitat utilization vary between fish and also seasonally. Such a complex range of behaviours may be a key component for achieving desirable outcomes for both conservation and fisheries in Marine Reserves.
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continuing trophic cascade effects after 25 years of no take Marine Reserve protection
Marine Ecology Progress Series, 2003Co-Authors: Nick T Shears, Russell C BabcockAbstract:Between 1978 and 1996 benthic communities in the Leigh Marine Reserve shifted from being dominated by sea urchins to being dominated by macroalgae. This was a result of a trophic cas- cade thought to be an indirect effect of increased predator abundance. We assessed further changes in communities from 1996 to 2000, differences in benthic communities between Reserve and adjacent unprotected sites, and the stability of these patterns from 1999 to 2001. Since 1996, densities of sea urchins Evechinus chloroticus have continued to decline in shallow areas of the Reserve (<8 m), and all sites classified as urchin barrens in 1978 are now dominated by large brown algae. Comparisons between Reserve and non-Reserve sites revealed differences consistent with a trophic cascade at Reserve sites. The greatest differences in algal communities between Reserve and non-Reserve sites occurred at depths where E. chloroticus was most abundant (4 to 6 m). Reserve sites had lower urchin densities and reduced extent of urchin barrens habitat with higher biomass of the 2 dominant algal species (Ecklonia radiata and Carpophyllum maschalocarpum). At Reserve sites densities of exposed E. chloroticus (openly grazing the substratum) declined so that urchin barrens were completely ab- sent by 2001. Lower density of the limpet Cellana stellifera and higher densities of the turbinid gas- tropod Cookia sulcata at Reserve sites are thought to be responses to changes in habitat structure, representing additional indirect effects of increased predators. The overall difference in community types between Reserve and non-Reserve sites remained stable between 1999 and 2001. Localised urchin mortality events due to an unknown agent were recorded at some sites adjacent to the Marine Reserve. Only at 1 of these sites did exposed urchins decline below the critical density of 1 m -2 , which resulted in the total replacement of urchin barrens with macroalgae-dominated habitats. At other sites urchin barrens have remained stable. Declines in the limpet C. stellifera occurred across all sites between 1999 and 2001 and may be indirectly associated with urchin declines. Long-term changes in benthic communities in the Leigh Reserve and the stability of differences between Reserve and non- Reserve sites over time are consistent with gradual declines in urchin densities due to increased pre- dation on urchins, thus providing further evidence for a trophic cascade in this system. The rapid de- clines in urchin numbers at some unprotected sites, however, demonstrate how short-term disturbances, such as disease, may result in shifts in community types over much shorter time frames.
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evidence for long term site fidelity of snapper pagrus auratus within a Marine Reserve
New Zealand Journal of Marine and Freshwater Research, 2001Co-Authors: Trevor J Willis, Darren M Parsons, Russell C BabcockAbstract:Abstract Increases in the density of exploited species on unfished reefs logically implies that some individuals are at least temporarily resident, or show fidelity to a particular area. We tagged snapper (Pagrus auratus (Bloch & Schneider 1801)) in the Leigh Marine Reserve, New Zealand using visible implant fluorescent elastomer tags, recoverable by diver visual sightings without the need to recapture the fish. Batch tagging of snapper (n = 907) was done during an angling survey in June and December 1996, and individually coded tags were implanted by divers (n = 117) in January 1999. Snapper tagged during both programmes were recovered on irregular intervals from 1997 to 2000. There were 71 recoveries of batch tags within 500 m of their tagging sites, and these recoveries were still being made >3 years after tagging: Of individually coded fish, 49 (42%) were seen, sometimes repeatedly over several months, close to their respective tagging sites. These observations included snapper as small as 23 cm fork ...
Peter J Mumby - One of the best experts on this subject based on the ideXlab platform.
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Marine Reserve targets to sustain and rebuild unregulated fisheries
PLOS Biology, 2017Co-Authors: Nils C Krueck, Hugh P Possingham, Gabby N Ahmadia, Cynthia Riginos, Eric A Treml, Peter J MumbyAbstract:Overfishing threatens the sustainability of coastal Marine biodiversity, especially in tropical developing countries. To counter this problem, about 200 governments worldwide have committed to protecting 10%–20% of national coastal Marine areas. However, associated impacts on fisheries productivity are unclear and could weaken the food security of hundreds of millions of people who depend on diverse and largely unregulated fishing activities. Here, we present a systematic theoretic analysis of the ability of Reserves to rebuild fisheries under such complex conditions, and we identify maximum Reserve coverages for biodiversity conservation that do not impair long-term fisheries productivity. Our analysis assumes that fishers have no viable alternative to fishing, such that total fishing effort remains constant (at best). We find that realistic Reserve networks, which protect 10%–30% of fished habitats in 1–20 km wide Reserves, should benefit the long-term productivity of almost any complex fishery. We discover a “rule of thumb” to safeguard against the long-term catch depletion of particular species: individual Reserves should export 30% or more of locally produced larvae to adjacent fishing grounds. Specifically on coral reefs, where fishers tend to overexploit species whose dispersal distances as larvae exceed the home ranges of adults, decisions on the size of Reserves needed to meet the 30% larval export rule are unlikely to compromise the protection of resident adults. Even achieving the modest Aichi Target 11 of 10% “effective protection” can then help rebuild depleted catch. However, strictly protecting 20%–30% of fished habitats is unlikely to diminish catch even if overfishing is not yet a problem while providing greater potential for biodiversity conservation and fishery rebuilding if overfishing is substantial. These findings are important because they suggest that doubling or tripling the only globally enforced Marine Reserve target will benefit biodiversity conservation and higher fisheries productivity where both are most urgently needed.
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larval dispersal and movement patterns of coral reef fishes and implications for Marine Reserve network design
Biological Reviews, 2015Co-Authors: Aileen P. Maypa, Rebecca Weeks, Rene A Abesamis, Glenn R. Almany, Alison Green, K Rhodes, Mary Gleason, Peter J MumbyAbstract:Well-designed and effectively managed networks of Marine Reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in Marine Reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For Marine Reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual Reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical Marine species have been unavailable or inaccessible to practitioners responsible for Marine Reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self-recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of Marine Reserves in tropical Marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) Marine Reserves should be more than twice the size of the home range of focal species (in all directions), thus Marine Reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside Reserves; (ii) Reserve spacing should be <15 km, with smaller Reserves spaced more closely; and (iii) Marine Reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of Marine Reserve networks within broader ecological, socioeconomic and management contexts.
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Larval dispersal and movement patterns of coral reef fishes, and implications for Marine Reserve network design
Biological Reviews, 2015Co-Authors: Alison L. Green, Kevin L. Rhodes, Mary G. Gleason, Aileen P. Maypa, Rebecca Weeks, Rene A Abesamis, Glenn R. Almany, Peter J Mumby, Alan T. WhiteAbstract:Well-designed and effectively managed networks of Marine Reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in Marine Reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For Marine Reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual Reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical Marine species have been unavailable or inaccessible to practitioners responsible for Marine Reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move
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disentangling trophic interactions inside a caribbean Marine Reserve
Ecological Applications, 2010Co-Authors: Julie B. Kellner, Steven Y. Litvin, Fiorenza Micheli, Alan Hastings, Peter J MumbyAbstract:Recent empirical studies have demonstrated that human activities such as fishing can strongly affect the natural capital and services provided by tropical seascapes. However, policies to mitigate anthropogenic impacts can also alter food web structure and interactions, regardless of whether the regulations are aimed at single or multiple species, with possible unexpected consequences for the ecosystems and their associated services. Complex community response to management interventions have been highlighted in the Caribbean, where, contrary to predictions from linear food chain models, a reduction in fishing intensity through the establishment of a Marine Reserve has led to greater biomass of herbivorous fish inside the Reserve, despite an increased abundance of large predatory piscivores. This positive multi-trophic response, where both predators and prey benefit from protection, highlights the need to take an integrated approach that considers how numerous factors control species coexistence in both fished and unfished systems. In order to understand these complex relationships, we developed a general model to examine the trade-offs between fishing pressure and trophic control on reef fish communities, including an exploration of top-down and bottom-up effects. We then validated the general model predictions by parameterizing the model for a reef system in the Bahamas in order to tease apart the wide range of species responses to Reserves in the Caribbean. Combining the development of general theory and site-specific models parameterized with field data reveals the underlying driving forces in these communities and enables us to make better predictions about possible population and community responses to different management schemes. © 2010 by the Ecological Society of America.
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Disentangling trophic interactions inside a Caribbean Marine Reserve
Ecological Applications, 2010Co-Authors: Julie B. Kellner, Steven Y. Litvin, Fiorenza Micheli, Alan Hastings, Peter J MumbyAbstract:Recent empirical studies have demonstrated that human activities such as fishing can strongly affect the natural capital and services provided by tropical seascapes. However, policies to mitigate anthropogenic impacts can also alter food web structure and interactions, regardless of whether the regulations are aimed at single or multiple species, with possible unexpected consequences for the ecosystems and their associated services. Complex community response to management interventions have been highlighted in the Caribbean, where, contrary to predictions from linear food chain models, a reduction in fishing intensity through the establishment of a Marine Reserve has led to greater biomass of herbivorous fish inside the Reserve, despite an increased abundance of large predatory piscivores. This positive multi-trophic response, where both predators and prey benefit from protection, highlights the need to take an integrated approach that considers how numerous factors control species coexistence in both fished and unfished systems. In order to understand these complex relationships, we developed a general model to examine the trade-offs between fishing pressure and trophic control on reef fish communities, including an exploration of top-down and bottom-up effects. We then validated the general model predictions by parameterizing the model for a reef system in the Bahamas in order to tease apart the wide range of species responses to Reserves in the Caribbean. Combining the development of general theory and site-specific models parameterized with field data reveals the underlying driving forces in these communities and enables us to make better predictions about possible population and community responses to different management schemes.
Hugh P Possingham - One of the best experts on this subject based on the ideXlab platform.
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Marine Reserve targets to sustain and rebuild unregulated fisheries
PLOS Biology, 2017Co-Authors: Nils C Krueck, Hugh P Possingham, Gabby N Ahmadia, Cynthia Riginos, Eric A Treml, Peter J MumbyAbstract:Overfishing threatens the sustainability of coastal Marine biodiversity, especially in tropical developing countries. To counter this problem, about 200 governments worldwide have committed to protecting 10%–20% of national coastal Marine areas. However, associated impacts on fisheries productivity are unclear and could weaken the food security of hundreds of millions of people who depend on diverse and largely unregulated fishing activities. Here, we present a systematic theoretic analysis of the ability of Reserves to rebuild fisheries under such complex conditions, and we identify maximum Reserve coverages for biodiversity conservation that do not impair long-term fisheries productivity. Our analysis assumes that fishers have no viable alternative to fishing, such that total fishing effort remains constant (at best). We find that realistic Reserve networks, which protect 10%–30% of fished habitats in 1–20 km wide Reserves, should benefit the long-term productivity of almost any complex fishery. We discover a “rule of thumb” to safeguard against the long-term catch depletion of particular species: individual Reserves should export 30% or more of locally produced larvae to adjacent fishing grounds. Specifically on coral reefs, where fishers tend to overexploit species whose dispersal distances as larvae exceed the home ranges of adults, decisions on the size of Reserves needed to meet the 30% larval export rule are unlikely to compromise the protection of resident adults. Even achieving the modest Aichi Target 11 of 10% “effective protection” can then help rebuild depleted catch. However, strictly protecting 20%–30% of fished habitats is unlikely to diminish catch even if overfishing is not yet a problem while providing greater potential for biodiversity conservation and fishery rebuilding if overfishing is substantial. These findings are important because they suggest that doubling or tripling the only globally enforced Marine Reserve target will benefit biodiversity conservation and higher fisheries productivity where both are most urgently needed.
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incorporating uncertainty associated with habitat data in Marine Reserve design
Biological Conservation, 2013Co-Authors: Vivitskaia J D Tulloch, Hugh P Possingham, Stacy D Jupiter, Chris Roelfsema, Ayesha I T Tulloch, Carissa J KleinAbstract:Abstract One of the most pervasive forms of uncertainty in data used to make conservation decisions is error associated with mapping of conservation features. Whilst conservation planners should consider uncertainty associated with ecological data to make informed decisions, mapping error is rarely, if ever, accommodated in the planning process. Here, we develop a spatial conservation prioritization approach that accounts for the uncertainty inherent in coral reef habitat maps and apply it in the Kubulau District fisheries management area, Fiji. We use accuracy information describing the probability of occurrence of each habitat type, derived from remote sensing data validated by field surveys, to design a Marine Reserve network that has a high probability of protecting a fixed percentage (10–90%) of every habitat type. We compare the outcomes of our approach to those of standard Reserve design approaches, where habitat-mapping errors are not known or ignored. We show that the locations of priority areas change between the standard and probabilistic approaches, with errors of omission and commission likely to occur if Reserve design does not accommodate mapping accuracy. Although consideration of habitat mapping accuracy leads to bigger Reserve networks, they are unlikely to miss habitat conservation targets. We explore the trade-off between conservation feature representation and Reserve network area, with smaller Reserve networks possible if we give up on trying to meet targets for habitats mapped with a low accuracy. The approach can be used with any habitat type at any scale to inform more robust and defensible conservation decisions in Marine or terrestrial environments.
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effectiveness of Marine Reserve networks in representing biodiversity and minimizing impact to fishermen a comparison of two approaches used in california
Conservation Letters, 2008Co-Authors: Carissa J Klein, Charles Steinback, Astrid Scholz, Hugh P PossinghamAbstract:We compared the effectiveness of Marine Reserve networks designed using a numerical optimization tool with networks designed by stakeholders during the course of California's Marine Life Protection Act Initiative at representing biodiversity and minimizing estimated negative impacts to fishermen. We used the same spatial data representing biodiversity and recreational fishing effort that were used by the stakeholders to design Marine Reserves. In addition, we used commercial fishing data not explicitly available to the stakeholders. Networks of Marine Reserves designed with numerical optimization tools represented the same amount of each habitat, or more, and had less of an estimated impact on commercial and recreational fisheries than networks designed by the stakeholders. The networks designed by the stakeholders could have represented 2.0–9.5% more of each habitat with no additional impact on the fisheries. Of four different Marine Reserve proposals considered in the initiative, the proposal designed by fishermen was more efficient than the proposals designed by other stakeholder groups at representing biodiversity and minimizing impact to the fishing industry. These results highlight the necessity of using comprehensive information on fishing effort to design a Reserve network that efficiently minimizes negative socioeconomic impacts. We recommend that numerical optimization tools support, not replace, the stakeholder-driven Reserve design process along California's northern and southern coasts to help accomplish two of the initiative's core objectives: (1) Protect representative and unique Marine habitats, and (2) Minimize negative socioeconomic impacts. The involvement of stakeholders is necessary as additional factors important to Reserve design can not be considered using a numerical optimization tool.
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efficiency costs and trade offs in Marine Reserve system design
Environmental Modeling & Assessment, 2005Co-Authors: Romola R Stewart, Hugh P PossinghamAbstract:With Marine biodiversity conservation the primary goal for Reserve planning initiatives, a site's conservation potential is typically evaluated on the basis of the biological and physical features it contains. By comparison, socio-economic information is seldom a formal consideration of the Reserve system design problem and generally limited to an assessment of threats, vulnerability or compatibility with surrounding uses. This is perhaps surprising given broad recognition that the success of Reserve establishment is highly dependent on widespread stakeholder and community support. Using information on the spatial distribution and intensity of commercial rock lobster catch in South Australia, we demonstrate the capacity of mathematical Reserve selection procedures to integrate socio-economic and biophysical information for Marine Reserve system design. Analyses of trade-offs highlight the opportunities to design representative, efficient and practical Marine Reserve systems that minimise potential loss to commercial users. We found that the objective of minimising the areal extent of the Reserve system was barely compromised by incorporating economic design constraints. With a small increase in area (<3%) and boundary length (<10%), the economic impact of Marine Reserves on the commercial rock lobster fishery was reduced by more than a third. We considered also how a Reserve planner might prioritise conservation areas using information on a planning units selection frequency. We found that selection frequencies alone were not a reliable guide for the selection of Marine Reserve systems, but could be used with approaches such as summed irreplaceability to direct conservation effort for efficient Marine Reserve design.
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Efficiency, costs and trade-offs in Marine Reserve system design
Environmental Modeling & Assessment, 2005Co-Authors: Romola R Stewart, Hugh P PossinghamAbstract:With Marine biodiversity conservation the primary goal for Reserve planning initiatives, a site's conservation potential is typically evaluated on the basis of the biological and physical features it contains. By comparison, socio-economic information is seldom a formal consideration of the Reserve system design problem and generally limited to an assessment of threats, vulnerability or compatibility with surrounding uses. This is perhaps surprising given broad recognition that the success of Reserve establishment is highly dependent on widespread stakeholder and community support. Using information on the spatial distribution and intensity of commercial rock lobster catch in South Australia, we demonstrate the capacity of mathematical Reserve selection procedures to integrate socio-economic and biophysical information for Marine Reserve system design. Analyses of trade-offs highlight the opportunities to design representative, efficient and practical Marine Reserve systems that minimise potential loss to commercial users. We found that the objective of minimising the areal extent of the Reserve system was barely compromised by incorporating economic design constraints. With a small increase in area (
Garry R. Russ - One of the best experts on this subject based on the ideXlab platform.
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Responses of coral reef wrasse assemblages to disturbance and Marine Reserve protection on the Great Barrier Reef
Marine Biology, 2019Co-Authors: J. R. Lowe, Daniela M. Ceccarelli, D H Williamson, R D Evans, Garry R. RussAbstract:Coral reefs are periodically impacted by disturbance events that reduce live coral cover and habitat complexity, with concomitant effects on fish assemblage structure. While the density of some fish species may increase following coral loss, most species decline. Determining which species are ‘winners’ and ‘losers’ following disturbances is fundamental to inform projections of future reef community structure, biodiversity, and productivity. Here, we analyse a long-term (2006–2018), spatially extensive (≈ 700 km) ‘natural experiment’ in which the responses of 11 wrasse taxa to acute disturbance events and no-take Marine Reserve (NTMR) protection were quantified on fringing coral reefs in the Palm (18°34′ S, 146°29′ E), Whitsunday (20°08′ S, 148°56′ E), and Keppel Island (23°10′ S, 150°57′ E) groups, Great Barrier Reef, Australia. The responses of wrasse densities to benthic habitat change were taxa specific and temporally consistent. Disturbance-mediated reductions in live hard coral cover and/or habitat complexity resulted in density declines for Hemigymnus melapterus, Hemigymnus fasciatus, Cheilinus fasciatus, Labroides spp., Oxycheilinus digramma, and Thalassoma spp. Conversely, Halichoeres spp. densities correlated positively with increased relative cover of sand and rubble, while Stethojulis spp., Anampses spp., Epibulus insidiator, and Bodianus spp. displayed variable responses to habitat changes. No wrasses exhibited an NTMR effect and predator density, irrespective of NTMR status, only influenced five taxa across all island groups. The lack of NTMR effects and variable top-down predator effects suggest that taxa-specific benthic habitat associations were the predominant drivers of wrasse densities on inshore GBR reefs.
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off reef planktivorous reef fishes respond positively to decadal scale no take Marine Reserve protection and negatively to benthic habitat change
Marine Ecology, 2017Co-Authors: Garry R. Russ, Oscar D Allerrojas, Justin R Rizzari, Angel C AlcalaAbstract:The effects of no-take Marine Reserve (NTMR) protection and changes in benthic habitat on fusiliers (family Caesionidae) were investigated at four small Philippine offshore islands on time scales of 10–31 years. Fusiliers are highly mobile, schooling, medium-sized planktivorous fish that generally feed “off-reef.” For these reasons, and given the small size of the NTMRs (3.6–37.5 ha) in this study, it was predicted that fusilier density would be unlikely to show clear effects of NTMR protection, or to respond to changes in benthic habitat. In contrast to predictions, clear NTMR effects were observed on fusilier density at three of the four NTMRs, with durations of protection from 14 to 31 years. Furthermore, the study provided strong evidence that benthic variables, specifically cover of live hard coral and dead substratum, affect the density of fusiliers. This effect of benthic habitat on density was highlighted by several major environmental disturbances that caused shifts in the benthic habitat from live hard coral to dead substratum. For two of the three most abundant species of fusiliers individually, and for all three of them combined (Pterocaesio pisang + Caesio caerulaurea + Pterocaesio digramma/tessellata), as live hard coral cover decreased, fish density decreased. It is hypothesized that these “off-reef” daytime feeders may have such a strong association with live hard coral cover because they use this habitat as nocturnal sleeping sites. Multivariate analyses indicated that, across all sites and times sampled, cover of live hard coral and dead substratum accounted for 38% of the variation in fish assemblage structure. These results are important as there are very few reports in the published literature of strong effects of NTMR protection or changes in benthic habitat on the density and assemblage structure of fusiliers.
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how much does the fishery at apo island benefit from spillover of adult fish from the adjacent Marine Reserve
2006Co-Authors: Rene Abesamis, Angel C Alcala, Garry R. RussAbstract:The contribution of the no-take Marine Reserve at Apo Island, Philippines, to local fishery yield through "spillover" (net export of adult fish) was estimated. Spatial patterns of fishing effort, yield, and catch rates around Apo Island were documented daily in 2003-2004. Catch rates were higher near the Reserve (by a factor of 1.1 to 2.0), but fishing effort was often lowest there. Higher catch rates near the Reserve were more likely due to spillover than to low fishing intensity. Lower fishing effort near the Reserve may have been due to 1) weather patterns, 2) traditional importance of other fishing grounds, 3) high variability in catch rates, 4) lower market value of target species, and 5) social pressures. The yield taken near the Reserve was only 10% of the total yield, but the actual spillover contribution was probably much less than this. This study is one of the few to estimate the spillover contribution to overall yield and to document the responses of fishermen to spillover.
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gradients of abundance of fish across no take Marine Reserve boundaries evidence from philippine coral reefs
Aquatic Conservation-marine and Freshwater Ecosystems, 2006Co-Authors: Rene Abesamis, Garry R. Russ, Angel C AlcalaAbstract:1. An abundance gradient from high inside to low outside a no-take Marine Reserve may indicate net emigration of adult fish from the Reserve (spillover). 2. We examined spatial patterns of abundance of fish across two 900 m long sections of coral reef slope at each of two small Philippine islands (Apo and Balicasag). One section sampled the entire length of a no-take Reserve and extended 200-400 m outside the two lateral Reserve boundaries. The other section, without a Reserve, was a control. The Reserves had had 20 (Apo) and 15 (Balicasag) years of protection when sampled in 2002. 3. Significant spatial gradients of decreasing abundance of target fish occurred across only one (Apo Reserve northern boundary = ARNB) of four real Reserve boundaries, and across none of the control boundaries. Abundance of non-target fish did not decline significantly across Reserve boundaries. 4. Abundance of target fish declined sharply 50 m outside the ARNB, but enhanced abundance extended 100-350 m beyond this boundary, depending on fish mobility. 5. Density of sedentary target fish declined 2-6 times faster than density of highly vagile and vagile target fish across the ARNB. 6. Habitat factors could not account for these ARNB results for target fish, but did influence abundance patterns of non-target fish. 7. The lack of abundance gradients of target fish at Balicasag may reflect reduced fishing outside the Reserve since it was established. 8. Apo Reserve had a gradient of abundance of target fish across at least one boundary, a result consistent with spillover.
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Marine Reserve benefits local fisheries
Ecological Applications, 2004Co-Authors: Garry R. Russ, Aileen P. Maypa, Angel C Alcala, Hilconida P Calumpong, Alan T. WhiteAbstract:The utility of no-take Marine Reserves as fisheries-management tools is controversial. It is hypothesized that Marine Reserves will help to sustain fisheries external to them by becoming net exporters of adults (the “spillover effect”) and net exporters of propagules (the “recruitment effect”). Local fishery benefits from spillover will likely generate support from fishing communities for Marine Reserves. We used underwater visual census to show that biomass of Acanthuridae (surgeonfish) and Carangidae (jacks), two families of reef fish that account for 40–75% of the fishery yield from Apo Island, Philippines, tripled in a well-protected no-take Reserve over 18 years (1983–2001). Biomass of these families did not change significantly over the same period at a site open to fishing. The Reserve protected 10% of the total reef fishing area at the island. Outside the Reserve, biomass of these families increased significantly closer to (200–250 m) than farther away from (250–500 m) the Reserve boundary over time. We used published estimates of fishery catch and effort, and fisher interviews (creel surveys) to show that the total catch of Carangidae and Acanthuridae combined at Apo Island was significantly higher after (1985–2001) than before (1981) Reserve establishment. Hook-and-line catch per unit effort (CPUE) at the island was 50% higher during 1998–2001 (Reserve protected 16–19 years) than during 1981–1986 (pre-Reserve and early phases of Reserve protection). Total hook-and-line effort declined by 46% between 1986 and 1998–2001. Hook-and-line CPUE of Acanthuridae was significantly higher close to (within 200 m) than far from the Reserve. CPUE of Carangidae was significantly higher away from the Reserve, possibly reflecting a local oceanographic effect. The benefits of the Reserve to local fisheries at the island were higher catch, increased catch rate, and a reduction in fishing effort. The fishery and tourism benefits generated by the Reserve have enhanced the living standard of the fishing community.
Kevin Leleu - One of the best experts on this subject based on the ideXlab platform.
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mapping habitats in a Marine Reserve showed how a 30 year trophic cascade altered ecosystem structure
Biological Conservation, 2012Co-Authors: Kevin Leleu, Brice Remyzephir, Roger Grace, Mark J CostelloAbstract:Abstract Time-series studies have reported trophic cascades in land, freshwater and Marine environments in many geographic areas. However, the spatial extent of habitats, a key metric of ecosystem structure, has not been mapped in these studies. Marine Reserves can provide experimental, before–after and inside–outside (control-impacted), situations for assessing the impact of fishing on ecosystems. We mapped seabed habitats and their associated communities (biotopes) in New Zealand’s oldest Marine Reserve for comparison with pre-Reserve maps created about 30 years previously. Areas grazed bare by sea urchins were entirely replaced in the centre of the Reserve by kelp, or alga turf, an intermediate biotope between heavily grazed encrusting algae and lightly grazed kelp. Urchins declined following increased abundance and body size of spiny (rock) lobsters and fish (especially snapper) in the Reserve but maintained bare rock outside. While this gradient in habitat change matched the gradient of predator abundance, it also matched the extent of reef habitat area. Thus the trophic cascade may be influenced by the effect of habitat on the abundance and behavioural interactions of urchins and their predators. Further ecosystem changes may arise should the abundance of mega-predators, such as seals, cetaceans and large sharks, increase in the region; if parasites become pathogenic; and/or when invasive species reach the Reserve. No-take Marine Reserves provide real-world experiments that show the importance of species in food webs, and the consequences of fishing for ecosystems. Because these changes in ecosystem structure may continue, and will vary with environment, climate and species distributions, Reserves need to be permanent and replicated geographically. Habitat maps should be produced for all Reserves to enable ecological changes in the ecosystem to be spatially quantified.