A General Business Model for Marine Reserves

Marine reserves are an effective tool for protecting biodiversity locally, with potential economic benefits including enhancement of local fisheries, increased tourism, and maintenance of ecosystem services. However, fishing communities often fear short-term income losses associated with closures, and thus may oppose marine reserves. Here we review empirical data and develop bioeconomic models to show that the value of marine reserves (enhanced adjacent fishing + tourism) may often exceed the pre-reserve value, and that economic benefits can offset the costs in as little as five years. These results suggest the need for a new business model for creating and managing reserves, which could pay for themselves and turn a profit for stakeholder groups. Our model could be expanded to include ecosystem services and other benefits, and it provides a general framework to estimate costs and benefits of reserves and to develop such business models.     

Rapid Effects of Marine Reserves via Larval Dispersal

Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest.     

Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs

The fisheries and biodiversity benefits of marine reserves are widely recognised but there is mounting interest in exploiting the importance of herbivorous fishes as a tool to help ecosystems recover from climate change impacts. This approach might be particularly suitable for coral reefs, which are acutely threatened by climate change, yet the trophic cascades generated by reserves are strong enough that they might theoretically enhance the rate of coral recovery after disturbance. However, evidence for reserves facilitating coral recovery has been lacking. Here we investigate whether reductions in macroalgal cover, caused by recovery of herbivorous parrotfishes within a reserve, have resulted in a faster rate of coral recovery than in areas subject to fishing. Surveys of ten sites inside and outside a Bahamian marine reserve over a 2.5-year period demonstrated that increases in coral cover, including adjustments for the initial size-distribution of corals, were significantly higher at reserve sites than those in non-reserve sites. Furthermore, macroalgal cover was significantly negatively correlated with the change in total coral cover over time. Recovery rates of individual species were generally consistent with small-scale manipulations on coral-macroalgal interactions, but also revealed differences that demonstrate the difficulties of translating experiments across spatial scales. Size-frequency data indicated that species which were particularly affected by high abundances of macroalgae outside the reserve had a population bottleneck restricting the supply of smaller corals to larger size classes. Importantly, because coral cover increased from a heavily degraded state, and recovery from such states has not previously been described, similar or better outcomes should be expected for many reefs in the region. Reducing herbivore exploitation as part of an ecosystem-based management strategy for coral reefs appears to be justified.     

Optimal Egg Size in Marine Invertebrates: Theory and Phylogenetic Analysis of the Critical Relationship between Egg Size and Development Time in Echinoids

Life-history models for marine invertebrate larvae generally predict a dichotomy in egg size in different species: eggs should be either minimal in size or large enough to support development fully without larval feeding. This prediction is contradicted, however, by the empirical observation of wide, continuous variation in egg size between these extremes. The prediction of dichotomy rests on the assumption of a negative linear relationship between egg size and development time. Here, I present a simple model in which development time is inversely proportional to egg size. Incorporating this relationship into an optimality model produces predictions of intermediate rather than extreme egg size. Modeled variations in mortality, food availability, fertilization rates, and temperature all produce continuous shifts in the value of the intermediate optimal size, in direct contrast to those produced by previous models, which predict shifts between two extreme optima. Empirical data on echinoid egg size and development time strongly support the model's assumption of an inverse proportional relationship between egg size and development time. A composite phylogeny is constructed of the 37 species for which egg size, development time, water temperature, and phylogenetic relatedness are known. Independent contrasts are made of the evolutionary changes in egg size and development time. This analysis indicates that evolutionary shifts in development time are correlated with the inversely proportional shifts in egg size assumed in the model. The assumption of a negative linear relationship used in previous models is rejected. This model provides a potential explanation for intraspecific variation in egg size along environmental gradients, sympatric differences in egg size among species, and biogeographic trends in egg size and development mode across taxa.     

Marine Reserves: from Beverton and Holt to the Present

The idea of using marine reserves, where all fishing is banned is not new to fisheries management. It was first formally considered by Beverton and Holt but rejected in favour of approaches such as fleet and gear control. Since that analysis, many fisheries have collapsed worldwide, illustrating the vulnerability of fishery resources and the ineffectiveness of these approaches. Empirical data and modelling suggest that marine reserves would generally increase yields, especially at the high fishing mortality that occurs in most fisheries. However, the most interesting feature of reserves is their ability to provide resilience to overexploitation, thereby reducing the risk of stock collapse. Benefits from reserves come from the increase in biomass and individual size within them, resulting in adult migration and/or larval dispersal that would replenish fishing grounds. The use of marine reserves in managing fisheries necessitates a thorough understanding of critical habitat requirements, fish movement, fish behaviour, the relations between subpopulations and the critical density effect for larval dispersal. When properly designed, and coupled with other management practices, reserves may provide a better insurance against uncertainties in stock assessment, fishing control and management by protecting a part of the population from exploitation. This strategy can be used for both sedentary and migratory species.     

Increased Disease Calls for a Cost-Benefits Review of Marine Reserves

Marine reserves (or No-Take Zones) are implemented to protect species and habitats, with the aim of restoring a balanced ecosystem. Although the benefits of marine reserves are commonly monitored, there is a lack of insight into the potential detriments of such highly protected waters. High population densities attained within reserves may induce negative impacts such as unfavourable trophic cascades and disease outbreaks. Hence, we investigated the health of lobster populations in the UK’s Marine Conservation Zone (MCZ) at Lundy Island. Comparisons were made between the fished, Refuge Zone (RZ) and the un-fished, No-Take Zone (NTZ; marine reserve). We show ostensibly positive effects such as increased lobster abundance and size within the NTZ; however, we also demonstrate apparent negative effects such as increased injury and shell disease. Our findings suggest that robust cost-benefit analyses of marine reserves could improve marine reserve efficacy and subsequent management strategies.     

A Test of the Higher-Taxon Approach in the Identification of Candidate Sites for Marine Reserves

Alternatives to species-level identification have been advocated as one solution to the problem of selecting marine reserves with limited information on the distribution of marine biodiversity.This study evaluated the effects on selection of candidate sites for marine reserves from using the higher-taxon approach as a surrogate for species-level identification of intertidal molluscs and rocky reef fishes. These effects were evaluated by determining the percentage of species included in candidate reserves identified from genus-, family- and order-level data by a complementarity-based reserve selection algorithm, and by testing for correlations between the irreplaceability values of locations. Candidate reserves identified from genus- and family-level data of intertidal molluscs included a similar percentage of all species as the reserves identified from species-level data. Candidate reserves selected from genus- and family-level data of rocky reef fishes included, respectively, 3–7% and 14–23% fewer species than reserves selected from species-level data. When the reserve identification process was constrained by a practical planning limit (a maximum of 20% locations able to be reserved) the reserves selected from genus- and family-level data of intertidal molluscs, and genus-level data of rocky reef fishes, included a similar percentage of species as the reserves identified from species-level data. Irreplaceability values of locations for species, genera and families of intertidal molluscs were highly correlated, and irreplaceability values of locations for species and genera of rocky reef fishes were highly correlated. This study suggests that genus- and family-level data for intertidal molluscs, and genus-level data for rocky reef fishes, are suitable surrogates for species in the identification of candidate sites for marine reserves.     

Test of the Optimal Body Size Model for Strepsirhines

We determined if data on strepsirhine body and home range sizes support an optimal body size (OBS) model of 100 g, as predicted from studies of energetics in terrestrial mammals. We also tested the following predictions of the OBS model: 1) relationships between body and home range sizes will change slope and sign above and below the OBS threshold of 100 g and 2) best-fit lines for OBS regression models (above and below the 100-g threshold) will intersect at ca. 100 g (range of 80–250 g). We collected data on body mass, home range size, and vertical ranging behavior for 37 strepsirhines from the literature. Linear regression analyses and phylogenetic independent contrasts methods revealed that body size is a significant determinant of both 2-dimensional (ha) and 3-dimensional (km³) home range sizes only in taxa weighing >100 g. There were consistent changes in the sign of the slopes above and below the OBS threshold. The intersections of the best-fit lines were within the OBS range for the body size to 3-dimensional home range comparisons. Thus, the data provide some support for the OBS model in strepsirhines. However, no regression model was statistically significant for the taxa below the OBS threshold, which may reflect small sample sizes. Also, no slope differed significantly between taxa above and below the OBS. Significant correlations between body and home range sizes for the complete data sets refute the √-shaped constraint space predicted via the OBS model.     

Small-Scale Habitat Structure Modulates the Effects of No-Take Marine Reserves for Coral Reef Macroinvertebrates

No-take marine reserves are one of the oldest and most versatile tools used across the Pacific for the conservation of reef resources, in particular for invertebrates traditionally targeted by local fishers. Assessing their actual efficiency is still a challenge in complex ecosystems such as coral reefs, where reserve effects are likely to be obscured by high levels of environmental variability. The goal of this study was to investigate the potential interference of small-scale habitat structure on the efficiency of reserves. The spatial distribution of widely harvested macroinvertebrates was surveyed in a large set of protected vs. unprotected stations from eleven reefs located in New Caledonia. Abundance, density and individual size data were collected along random, small-scale (20×1 m) transects. Fine habitat typology was derived with a quantitative photographic method using 17 local habitat variables. Marine reserves substantially augmented the local density, size structure and biomass of the target species. Density of Trochus niloticus and Tridacna maxima doubled globally inside the reserve network; average size was greater by 10 to 20% for T. niloticus. We demonstrated that the apparent success of protection could be obscured by marked variations in population structure occurring over short distances, resulting from small-scale heterogeneity in the reef habitat. The efficiency of reserves appeared to be modulated by the availability of suitable habitats at the decimetric scale (“microhabitats”) for the considered sessile/low-mobile macroinvertebrate species. Incorporating microhabitat distribution could significantly enhance the efficiency of habitat surrogacy, a valuable approach in the case of conservation targets focusing on endangered or emblematic macroinvertebrate or relatively sedentary fish species     

On the Minute Size of Mitochondria

In very small systems chemical reactions may, it is suggested,take on a periodic or oscillatory character. This would meanthat organelles such as mitochondria might become the centerof elastic and electromagnetic radiation. This possibility hasconsequences relevant to the problems of uptake, cell microstructureand protein synthesis, amongst other things.     

Changes in Fish Assemblages following the Establishment of a Network of No-Take Marine Reserves and Partially-Protected Areas

Networks of no-take marine reserves and partially-protected areas (with limited fishing) are being increasingly promoted as a means of conserving biodiversity. We examined changes in fish assemblages across a network of marine reserves and two different types of partially-protected areas within a marine park over the first 5 years of its establishment. We used Baited Remote Underwater Video (BRUV) to quantify fish communities on rocky reefs at 20–40 m depth between 2008–2011. Each year, we sampled 12 sites in 6 no-take marine reserves and 12 sites in two types of partially-protected areas with contrasting levels of protection (n = 4 BRUV stations per site). Fish abundances were 38% greater across the network of marine reserves compared to the partially-protected areas, although not all individual reserves performed equally. Compliance actions were positively associated with marine reserve responses, while reserve size had no apparent relationship with reserve performance after 5 years. The richness and abundance of fishes did not consistently differ between the two types of partially-protected areas. There was, therefore, no evidence that the more regulated partially-protected areas had additional conservation benefits for reef fish assemblages. Overall, our results demonstrate conservation benefits to fish assemblages from a newly established network of temperate marine reserves. They also show that ecological monitoring can contribute to adaptive management of newly established marine reserve networks, but the extent of this contribution is limited by the rate of change in marine communities in response to protection.     

The Effect of Variability on the Optimal Size of a Feeding Territory

Previous empirical and theoretical work has focused on how feedingterritory size is governed by average levels of food availabilityand intrusion pressure; the potentially important effects ofvariability have not yet been studied in detail. Here I incorporatevariation in food availability and intrusion pressure in somesimple optimality models of territory size. The results showthat the possible effects of variability are diverse, includingboth increase and decrease in territory size. And in some cases,variation in food availability produces qualitatively differenteffects than variation in intrusion pressure.     

A Model To Estimate the Optimal Sample Size for Microbiological Surveys

Estimating optimal sample size for microbiological surveys is a challenge for laboratory managers. When insufficient sampling is conducted, biased inferences are likely; however, when excessive sampling is conducted valuable laboratory resources are wasted. This report presents a statistical model for the estimation of the sample size appropriate for the accurate identification of the bacterial subtypes of interest in a specimen. This applied model for microbiology laboratory use is based on a Bayesian mode of inference, which combines two inputs: (ii) a prespecified estimate, or prior distribution statement, based on available scientific knowledge and (ii) observed data. The specific inputs for the model are a prior distribution statement of the number of strains per specimen provided by an informed microbiologist and data from a microbiological survey indicating the number of strains per specimen. The model output is an updated probability distribution of strains per specimen, which can be used to estimate the probability of observing all strains present according to the number of colonies that are sampled. In this report two scenarios that illustrate the use of the model to estimate bacterial colony sample size requirements are presented. In the first scenario, bacterial colony sample size is estimated to correctly identify Campylobacter amplified restriction fragment length polymorphism types on broiler carcasses. The second scenario estimates bacterial colony sample size to correctly identify Salmonella enterica serotype Enteritidis phage types in fecal drag swabs from egg-laying poultry flocks. An advantage of the model is that as updated inputs from ongoing surveys are incorporated into the model, increasingly precise sample size estimates are likely to be made.     

The Role of Pre-Existing Disturbances in the Effect of Marine Reserves on Coastal Ecosystems: A Modelling Approach

We have used an end-to-end ecosystem model to explore responses over 30 years to coastal no-take reserves covering up to 6% of the fifty thousand square kilometres of continental shelf and slope off the coast of New South Wales (Australia). The model is based on the Atlantis framework, which includes a deterministic, spatially resolved three-dimensional biophysical model that tracks nutrient flows through key biological groups, as well as extraction by a range of fisheries. The model results support previous empirical studies in finding clear benefits of reserves to top predators such as sharks and rays throughout the region, while also showing how many of their major prey groups (including commercial species) experienced significant declines. It was found that the net impact of marine reserves was dependent on the pre-existing levels of disturbance (i.e. fishing pressure), and to a lesser extent on the size of the marine reserves. The high fishing scenario resulted in a strongly perturbed system, where the introduction of marine reserves had clear and mostly direct effects on biomass and functional biodiversity. However, under the lower fishing pressure scenario, the introduction of marine reserves caused both direct positive effects, mainly on shark groups, and indirect negative effects through trophic cascades. Our study illustrates the need to carefully align the design and implementation of marine reserves with policy and management objectives. Trade-offs may exist not only between fisheries and conservation objectives, but also among conservation objectives.     

Beyond Marine Reserves: Exploring the Approach of Selecting Areas where Fishing Is Permitted,Rather than Prohibited

Background

Marine populations have been declining at a worrying rate, due in large part to fishing pressures. The challenge is to secure a future for marine life while minimizing impacts on fishers and fishing communities.

Methods and Principal Findings

Rather than selecting areas where fishing is banned – as is usually the case with spatial management – we assess the concept of designating areas where fishing is permitted. We use spatial catch statistics for thirteen commercial fisheries on Canada''s west coast to determine the minimum area that would be needed to maintain a pre-ascribed target percentage of current catches. We found that small reductions in fisheries yields, if strategically allocated, could result in large unfished areas that are representative of biophysical regions and habitat types, and have the potential to achieve remarkable conservation gains.

Conclusions

Our approach of selecting fishing areas instead of reserves could help redirect debate about the relative values that society places on conservation and extraction, in a framework that could gain much by losing little. Our ideas are intended to promote discussions about the current status quo in fisheries management, rather than providing a definitive solution.     

Optimal foraging area: Size and allocation of search effort

A model is derived for the optimal spatial allocation of foraging effort for an animal returning with food to a central place in a uniform habitat. The forager is assumed to maximize its yield of food during a given period. Foraging effort is expended on search for food, and on transportation to the central place. It is shown that the allocation of search has been optimal if and only if the “marginal cost” of additional food is equal throughout the foraging area when the period has elapsed. The model is used to predict the optimal area radius and allocation of search time. With realistic parameter values, the optimal time per unit area roughly decreases linearly with the distance from the central place. The influence of food density and forager characteristics is examined.     

Influence of Coral Reef Rugosity on Fish Communities in Marine Reserves Around Lombok Island,Indonesia

Environmental Biology of Fishes - Coral reef structural form is widely considered a key factor with respect to the availability of shelter and foraging spaces for fishes and invertebrates. However,...     

Derelict Fishing Line Provides a Useful Proxy for Estimating Levels of Non-Compliance with No-Take Marine Reserves

No-take marine reserves (NTMRs) are increasingly being established to conserve or restore biodiversity and to enhance the sustainability of fisheries. Although effectively designed and protected NTMR networks can yield conservation and fishery benefits, reserve effects often fail to manifest in systems where there are high levels of non-compliance by fishers (poaching). Obtaining reliable estimates of NTMR non-compliance can be expensive and logistically challenging, particularly in areas with limited or non-existent resources for conducting surveillance and enforcement. Here we assess the utility of density estimates and re-accumulation rates of derelict (lost and abandoned) fishing line as a proxy for fishing effort and NTMR non-compliance on fringing coral reefs in three island groups of the Great Barrier Reef Marine Park (GBRMP), Australia. Densities of derelict fishing line were consistently lower on reefs within old (>20 year) NTMRs than on non-NTMR reefs (significantly in the Palm and Whitsunday Islands), whereas line densities did not differ significantly between reefs in new NTMRs (5 years of protection) and non-NTMR reefs. A manipulative experiment in which derelict fishing lines were removed from a subset of the monitoring sites demonstrated that lines re-accumulated on NTMR reefs at approximately one third (32.4%) of the rate observed on non-NTMR reefs over a thirty-two month period. Although these inshore NTMRs have long been considered some of the best protected within the GBRMP, evidence presented here suggests that the level of non-compliance with NTMR regulations is higher than previously assumed.