Logging degrades nursery habitat for an iconic coral reef fish

Biological Conservation 210 (2017) 273–280

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Biological Conservation journal homepage: www.elsevier.com/locate/biocon

Logging degrades nursery habitat for an iconic coral reef fish a,b,⁎

b,c

d

e

Richard J. Hamilton , Glenn R. Almany , Christopher J. Brown , John Pita , Nathan A. Petersona, J. Howard Choatf

MARK

a

The Nature Conservancy, Asia Pacific Resource Centre, 48 Montague Road, South Brisbane, QLD 4101, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia CRIOBE, USR 3278, CNRS–EPHE–UPVD, Laboratoire d'Excellence “CORAIL”, 58 Avenue Paul Alduy, 66860 Perpignan Cedex, France d Australian Rivers Institute, Griffith University, Nathan 4111, Australia e The Nature Conservancy, Isabel Environmental Office, Buala, Isabel Province, Solomon Islands f College of Marine and Environmental Studies, James Cook University, Townsville, QLD 4811, Australia b c

A R T I C L E I N F O

A B S T R A C T

Keywords: Coral reef fisheries Recruitment Habitat loss Bolbometopon muricatum Solomon Islands

The loss of nursery habitats is widely believed to contribute disproportionally to declines in abundance and productivity of fish populations. However, it has been difficult to establish links between the processes threatening nurseries and changes in population demography. Here we show that juvenile bumphead parrotfish (Bolbometopon muricatum), an iconic coral reef species that is globally threatened, depend on a highly specific micro-habitat that is vulnerable to sedimentation from logging operations. We conducted surveys on fringing reefs in Solomon Islands. Surveys covered reefs around an island that has been selectively logged, and an island where there has been no logging. B. muricatum juveniles were restricted to shallow lagoonal reefs that fringed mangrove forested shorelines and had a high proportion of live branching corals, with the smallest settlers found in Acropora aspera and Acropora micropthalma colonies that were occupied by damselfish. Statistical path models indicated a 24 times decline in juvenile abundance near logging operations due to the mediating effect of habitat loss, and a possible direct effect of sedimentation on abundance. Our study shows that sedimentation can pose a significant threat to near-shore coral reef fish and highlights the role of nursery habitats in sustaining recruitment to reef fish populations.

1. Introduction Effective fisheries management requires knowledge of the life history of target species, including ontogenetic trends in habitat use and associated sources of mortality (Wilson et al., 2010). Studies of threats to coral reef species have tended to focus on the impacts of fishing adult stocks (Rhodes et al., 2011; Robinson et al., 2015). However coral reef fish may also be threatened by loss of habitat. For instance, many coral reef fishes recruit into nearshore mangrove, seagrass and shallow coral reefs before making ontogenetic migrations to outer coral reefs (Beck et al., 2001; Mumby et al., 2004; McMahon et al., 2011). Nearshore habitats can be degraded by coastal development and runoff from human activities on land (Bartley et al., 2014), threatening the survival of juvenile fish (Beck et al., 2001; DeMartini et al., 2013) and impacting adult populations (Mateo et al., 2010; Wilson et al., 2010; McMahon et al., 2011). Thus, there is a need to assess the impacts of anthropogenic changes to recruitment habitats at scales that are meaningful for management intervention (Eggelston,

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1995; Mumby et al., 2004). Further, the linkage between human actions on land, loss of nursery habitat and changes in juvenile reef fish populations has been difficult to quantify. Such indirect sources of mortality may confound attempts to manage the impacts of fishing adult populations. For many coral reef fish species highly branching corals (e.g., Acropora, Pocillopora) that occur in shallow inshore areas may be very important settlement and recruitment habitats (Almany, 2004; Bonin et al., 2009; Ticzon et al., 2012; Wen et al., 2013). These branching corals are particularly vulnerable to logging, agriculture and mining that can cause increased sedimentation in nearshore marine environments, resulting in smothering of coral and low light conditions that hinder photosynthesis (see review by Bartley et al., 2014). Furthermore, many of branching coral species are particularly vulnerable to the effects of climate change, such as coral bleaching (McClanahan et al., 2004). Here we identify the settlement and recruitment habitat of Bolbometopon muricatum, the largest of the parrotfish species reaching

Corresponding author at: The Nature Conservancy, Asia Pacific Resource Centre, 48 Montague Road, South Brisbane, QLD 4101, Australia. E-mail address: [email protected] (R.J. Hamilton).

http://dx.doi.org/10.1016/j.biocon.2017.04.024 Received 15 December 2016; Received in revised form 8 April 2017; Accepted 21 April 2017 0006-3207/ © 2017 Elsevier Ltd. All rights reserved.


R.J. Hamilton et al.

Fig. 1. The logged island of Barofa Ite and the unlogged island of Barora Faa at the western end of Isabel Province, Solomon Islands. The location of log ponds (black stars) and the abundance of juvenile B. muricatum sighted at 49 UVC sites surveyed are also shown.

logging.

over 50 kg in weight and ages of 40 years (Hamilton and Choat, 2012; Andrews et al., 2015). B. muricatum is significant to conservation because it is an ecological important habitat engineer (Bellwood et al., 2003), and because its protection serendipitously benefits a broad range of other species (Olds et al., 2014). B. muricatum is listed as threatened on the IUCN Red list, with widespread population declines largely attributed to overfishing (Dulvy and Polunin, 2004; Kobayashi et al., 2011; Hamilton and Choat, 2012). However, little is known about the settlement and recruitment dynamics of B. muricatum, which may have important consequences for population dynamics. The present study was conducted in the Kia District of Isabel Province, Solomon Islands. This region has supported a small-scale commercial spearfishery for adult B. muricatum since 2001 (Hamilton et al., 2016). Over the same time period that this spearfishery operated approximately 50% of the forests in the Kia District were logged (Peterson et al., 2012) by commercial operators that are known to use some of the worst selective logging practices in the tropics (Katovai et al., 2015). In this study we provide the first quantitative description of the juvenile and settlement habitats of B. muricatum and quantify the impact of anthropogenic disturbance (logging) on the habitat. This information is used to resolve the following questions; 1) The location of the recruitment habitat and the influence of microhabitat structure on juvenile abundance; 2) the impact of logging on a) the habitat structure including branching corals b) the spatial pattern of abundance of juvenile B. muricatum at sites subject to logging; 3) the likely location and proportion of critical juvenile habitat that has been degraded by

2. Methods 2.1. Study location and environment The study was conducted in the Kia district at the western end of Isabel Province, Solomon Islands, extending from 7°19′ to 7°39′ S over a linear distance of 82 km. The environment is characterised by complex reefs with mangroves and coastal forests. Three under water visual census (UVC) surveys were conducted between 2012 and 2014 to determine 1) juvenile habitat 2) the influence of microhabitat and logging on juvenile abundance and 3) settlement microhabitat. 2.1.1. Juvenile habitat To determine the influence of major reef habitat types on adult B. muricatum abundance we conducted an underwater visual census (UVC) programme within the Kia study region. A total of 146 UVC surveys were completed across five reef strata (fringing reef, patch reef, back reef, fore reef, and subtidal reef flats) in October 2012 using 20 minute timed swims. The size of each B. muricatum sighted on a timed swim was estimated to the nearest centimetre (Electronic supplementary material, Fig. S1, Hamilton et al., 2016). Inspection of the UVC data revealed that juvenile B. muricatum (< 500 mm; Hamilton et al., 2008; Hamilton and Choat, 2012) were only ever sighted on sheltered lagoonal fringing reefs near mangroves, and consequently, we used 274



and re-suspension of sediment by tides and storm events.

geomorphological maps from the Millennium Coral Reef Mapping Project (Andrefouet et al., 2006) to further subdivide fringing reef UVC data into two categories; lagoonal fringing reef and exposed fringing reef.

2.1.3. Settlement microhabitat Observations during the 2013 survey suggested that new settlers (< 50 mm) only occur in Acropora colonies occupied by damselfish. To identify the key features of the settlement habitat, we resurveyed three lagoonal fringing reefs over three days in December 2014. We collected samples of the coral species inhabited by recently settled B. muricatum and the co-occurring fish species (damselfish). We also measured ten coral colonies at one site, and determined settler density within each colony. Thirty-eight juvenile B. muricatum were collected for demographic analysis.

2.1.2. Influence of microhabitat and logging on juvenile abundance While conducting fieldwork on the Kia B. muricatum fisheries in early 2012 (Hamilton et al., 2016), we heard numerous anecdotal accounts from local spearfishers of how sedimentation from logging had dramatically reduced the abundance of juvenile B. muricatum on fringing reefs adjacent to logged islands. Subsequently, in October 2012 two experienced SCUBA divers from Kia joined our UVC team. These two individuals each had twenty years of experience free diving throughout the Kia lagoons. On several different occasions, they expressed their disappointment that many of the fringing reef sites that were devoid of B. muricatum in our 2012 surveys had supported healthy branching coral reefs and high abundances of juvenile B. muricatum prior to nearby logging operations commencing. These compelling anecdotal accounts led us to conduct the 2013 UVC survey. Our 2013 UVC study focused on the sheltered lagoonal fringing reefs around Barora Faa and Barofa Ite islands (Fig. 1). By 2013 the forests of Barofa Ite and the adjacent Isabel mainland had been extensively logged, whereas Barora Faa forests had not been subjected to commercial logging (Peterson et al., 2012). To investigate how microhabitat and logging influenced juvenile abundance we conducted an underwater visual census (UVC) survey on fringing reefs in the Kia district from the 17th–26th October 2013. 22 fringing reefs adjacent to the logged island of Barofa Ite were surveyed and 27 fringing reefs adjacent to the unlogged island of Barora Faa were surveyed (Fig. 1). We also stratified UVCs by current flow (mild or high) based on local diver experience. The UVC team comprised 8 SCUBA divers working from two boats in teams of four and all surveys were carried out in 1 to 4 m water depth. At each location five 50 m transects were surveyed for juvenile fish and benthic cover, with a total of 245 transects completed. Fish surveys were conducted first; with transect tapes laid by an assistant following the fish observer. On each transect the size of each individual B. muricatum (length in mm) sighted 5 m either side of the transect midline were estimated and recorded, giving an area covered in each transect of 500 m2. We defined ‘new settlers’ as fish < 50 mm, since B. muricatum below this size were found in very specific microhabitats and had limited movement capacity. We defined ‘juveniles’ as fish between the lengths of 50–500 mm, since 500 mm is below the size of sexual maturity in this species (Hamilton et al., 2008; Hamilton and Choat, 2012). Benthic communities were surveyed along the same transects using a modified version of the Point Intercept Method (Hill and Wilkinson, 2004). Benthic composition was recorded at three points every 2 m along the 50 m transect tape. Two points were located one metre on either side of the transect line and the third was below the transect. This resulted in a total collection of 75 data points for each transect (375 points per site). Benthic composition was recorded based on life-forms consistent with the categories provided by English et al. (1994) with the addition of the categories Acropora Branching Dead and Coral Branching Dead (Electronic supplementary material, Table S1). At each site, we used a Secchi disk to measure water clarity as a proxy for suspended sediment. The Secchi disk was lowered into deep lagoonal water adjacent to the site prior to commencing the UVC survey. We used participatory mapping with local landowners from Kia (Peterson et al., 2012) to identify the locations and establishment dates of all log ponds on Barofa Ite and crossed checked the locations with site visits (Fig. 1). Log ponds are the locations where logs are stacked prior to being loaded onto barges, and they are constructed by bulldozing a large amount of sediment directly onto mangroves and shallow coral reefs (Electronic supplementary material, Video S1). The construction of log ponds causes a significant amount of sediment to enter and remain in lagoon systems via direct run off, log pond erosion

2.2. Statistical analysis From the 2012 UVC survey data we calculated the mean abundance per hectare and mean size (mm) of B. muricatum on lagoonal fringing reef, exposed fringing reef, back reef, patch reef, fore reef, and subtidal reef flats. We also calculated the mean abundance per hectare and mean size (mm) of B. muricatum sighted in the 2013 UVC lagoonal survey, and compared these mean sizes with a One Way Anova in Sigmastat (Systat Software, San Jose, California, USA). We fitted statistical path models to the 2013 UVC dataset to test alternative hypotheses for the impacts of logging on coral habitats and the abundance of juvenile B. muricatum (Shipley, 2000). We fitted several alternate path models that represent hypotheses about causal relationships among the presence of log ponds, habitat, current flow and juvenile abundance (Table 1). We tested each causal hypothesis using d-separation tests with Fisher's C statistic (Shipley, 2000), tests of d-separation were performed using the R programming package ‘piecewiseSEM’ (Lefcheck, 2016). Following convention we rejected models with p < 0.05, which indicates a low probability of generating the data given the specific hypothesis (Shipley, 2000; Shipley, 2009). Then, for each plausible path model (termed the ‘final models’), we estimated the total effect of logging (Imai et al., 2010) on juvenile abundance. Confidence intervals on abundances were obtained by nonparametric bootstrapping (Imai et al., 2010). For all path models, coral cover was a linear function of its predictors, assuming Gaussian errors, and checks of residuals confirmed this choice. Abundance counts were modeled using generalized linear models with negative-binomial errors and a log link (Venables and Ripley, 2002). For the final models, we plot the effects of each relationship included in the path model with 95% confidence intervals. For Gaussian models these effects represent the per-unit effects of each predictor on its response. For count models the estimates are for the effect of each predictor on logged abundance, thus each effect has a multiplicative impact on abundance. We checked the residuals of the final models for spatial autocorrelation by plotting semi-variograms using the over-water distance among sites and found no spatial structuring in residuals, so we did not include any spatial autocovariates in the models. To estimate the amount of juvenile habitat impacted by logging, we used the Millennium Coral Reef Mapping Project (Andrefouet et al., 2006) satellite images to identify suitable juvenile habitat in the region, based on the habitat classification of the juvenile surveys. 3. Results 3.1. Juvenile habitat 365 B. muricatum were sighted in the 2012 UVC survey (Hamilton et al., 2016), which covered all major reef habitats in the Kia fishing grounds (Electronic supplementary material, Fig. S1). B. muricatum < 500 mm were only ever recorded on lagoonal fringing reefs (Electronic supplementary material, Fig. S2), and the mean size of B. muricatum sighted on lagoonal fringing reefs was significantly lower than the mean 275



Table 1 Hypothesized causal relationships among B. muricatum abundance, habitat variables and logging, with test statistics. Diagrams showed hypothesized causal relationships, where arrows indicate that one variable was allowed to affect another. Model num.

Model

Independence claims

C-statistic

p-Value

1

1

20.5

< 0.0001

2

2

21.5

< 0.0001

3

2

4.86

0.088

size of B. muricatum sighted in all other exposed habitats (p < 0.001, Fig. 2). The mean size of B. muricatum sighted in our 2013 UVC survey of lagoonal fringing reefs (Fig. 2) was also significantly lower than the mean size sighted on lagoonal fringing reefs in 2012 (p < 0.001)

potential juvenile habitat had been lost by 2013 due to logging operations.

3.2. Influence of microhabitat and logging on juvenile abundance

In the 2013 and 2014 UVC surveys recently settled B. muricatum were only ever sighted in shallow (0.5–1 m) branching coral–algae assemblages on sheltered lagoonal reefs that fringe mangrove forested shorelines (Fig. 4a and d). The settlement habitat was highly specific, with the smallest B. muricatum found in Acropora aspera and to a lesser extent A. micropthalma colonies occupied by damselfish species Stegastes punctatus and Hemiglyphidodon plagiometopon (Fig. 4b and c). In the 2014 survey of ten A. aspera colonies [mean size 18.9 m2 (SD 7.7 m2)], the number of B. muricatum recruits ranged from 0 to 3 per colony, with a mean density of 1.6 (SD 1.8) recruits per A. aspera colony. B muricatum juveniles that were collected from A. aspera and A. micropthalma colonies ranged in size from 12 to 35 mm (n = 26) and individuals ranging from 25 to 58 mm (n = 12) were also found in A. reticulate. On numerous occasions in 2013 and 2014 we witnessed juveniles that exceed 50 mm being chased out of A. aspera and A. micropthalma colonies by resident damselfish (Electronic supplementary material, Video S2). These sheltered lagoonal fringing reefs also supported high abundances of juveniles of other locally important fishery species such as humphead wrasse (Chelinus undulatus), scarids and siganids (Electronic supplementary material, Video S3).

3.3. Settlement microhabitat

190 B. muricatum individuals were sighted in the 2013 juvenile survey (Fig. 1), of which 177 were juveniles < 500 mm (Electronic supplementary material, Fig. S3). We fitted four models for hypothesized causal relationships among B. muricatum abundance and habitat variables (Table 1). Models without a direct effect of logging (i.e. the first two in Table 1) were significant (p < 0.05) indicating the hypothesized causal structures did not adequately represent relationships in the data. A model including an effect of flow on coral cover and a direct effect of logging on abundance was insignificant (model 3, p > 0.05) (Fig. 3). Additional analyses supported an effect of logponds on coral cover with low water clarity at logged UVC sites (Electronic supplementary material, Fig. S4). Water quality increased farther from log ponds (Electronic supplementary material, Fig. S5) Taking the third model, we estimated the impact of logging was to reduce the abundance of B. muricatum by 24 times (9.4, 97.3 ± 95% C.I.). We apportioned this effect into a 1.8 times decline (1.06, 3.5 ± 95% C.I.) due to solely habitat loss and a 14 times decline (15.08, 102 ± 95% C.I.) due solely to the direct effect of logging on abundance. The estimated total area of suitable habitat (sheltered fringing reef) for juveniles in the Kia district was 3528 ha (Electronic supplementary material, Fig. S6). Juvenile habitat that is presumed lost by logging was delineated as those habitats within the zone of influence of logging ponds (i.e. primarily south side of the islands). Thus, the area of habitat that was estimated to be lost is 1941 ha, meaning that up to 55% of

4. Discussion B. muricatum faces a double jeopardy from human disturbances: its very large size, extended life span (40 years) and aggregating behavior make it susceptible to overfishing (Hamilton et al., 2016); and we have shown it has a highly specific recruitment habitat that is susceptible to 276



Fig. 2. Schematic indicating ontogenetic movements of B. muricatum and evidence to support the proposed migratory behavior: (a) abundance across different reef habitats and (b) mean size mm ( ± 1SE) across different reef habitats moving from inshore to exposed and offshore habitats. Note that data are pooled across the 2012 surveys (timed swim transects) and the 2013 juvenile surveys (transects).

unlogged islands. This double jeopardy in our opinion justifies the IUCN listing, despite a recommendation that it not be listed as either threatened or endangered under the U.S. Endangered Species Act in a recent status review (Kobayashi et al., 2011). The primary focus of this study was on the distribution of B. muricatum life-history stages across habitats and the sensitivity of these habitats to sedimentation from logging. Our focus on spatial patterns meant we were unable to quantify inter-annual variability in recruitment. However, our observations of fewer B. muricatum occurring in the region affected by log ponds are unlikely to have been caused by chance temporal variation in recruitment. First, there were comparable numbers of similarly sized settlers in the smaller sub-set of sites used for the 2014 micro-habitat study, which is suggestive of stable recruitment over 2013 and 2014. Second, our larger-scale 2013 survey included fish up to 480 mm that can be 5 years of age and thus likely spanned multiple year-classes of recruits. Third, at the time of this study there were large numbers of adults on outer reefs adjacent to the nursery areas that were affected by logging (Hamilton et al., 2016), suggesting this region had historically high juvenile recruitment in the past. The contribution of adult populations on outer reefs to near versus far-field juvenile recruitment is currently being investigated through a genetics parentage study. However, the most important factor with respect to the Isabel Island habitat was the local knowledge of community fishers, who had observed a decline in juvenile abundance in the logged region. Local knowledge can provide a historical perspective on the state of reef fish communities, which is often missing for tropical coastal fisheries that lack inter-annual scientific data collection (Johannes et al., 2000). Other species of reef fish also recruit into specific microhabitats (Wilson et al., 2010), including live branching Acropora corals (Bonin et al., 2009; Ticzon et al., 2012; Wen et al., 2013), presumably because these structurally complex habitats provide greater shelter from preda-

Fig. 3. Relationship among B. muricatum abundance, habitat, logging and flow strength. Numbers are mean effects (95% confidence intervals in brackets). Note that effects of coral cover and logging ponds represent effects on the natural log of B. muricatum abundance. Black arrows indicate positive effects, red arrows indicate negative effects. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

destruction. The unique features of this study are the integration of estimates of juvenile abundance with habitat structure and the magnitude of nearshore habitat loss, at a scale relevant to the management of this species. This included details of the nature of the settlement habitat (inshore acroporid corals occupied by damselfishes) and extent of the nursery habitat disturbance, which resulted in recruit populations near logged islands being 24 times less abundant than those adjacent to 277



a

c

d

b

Fig. 4. B. muricatum settle on shallow lagoonal reefs that fringe mangrove forested shorelines (a). The smallest juveniles in the 12–35 mm size range (b) were found in branching Acropora colonies occupied by damselfish (c). Larger juveniles occupied nearby structurally complex reefs intermixed with seagrass (d).

required to more clearly resolve the hypothesized non-linear relationship between coral cover and juvenile abundance. The cause of the direct logging effects are unknown, but there is a growing body of literature that demonstrates that high suspended sediment concentrations can be detrimental to larval and juvenile fish. High suspended sediment concentrations can reduce larval sensory abilities, interfering with their ability to feed effectively and locate preferred microhabitats at the time of settlement (Wenger et al., 2011; Wenger et al., 2012). Exposure to moderate to high levels of suspended sediment can also impair gill function and make larvae more susceptibility to diseases (Hess et al., 2015). In recent decades populations of B. muricatum have declined globally (Dulvy and Polunin, 2004; Kobayashi et al., 2011; Hamilton and Choat, 2012). Declines of B. muricatum are typically attributed to fishing pressure, however our study suggests that poor water quality may also contribute. In the Kia region we estimated 55% of potential juvenile habitat has already been lost due to recent logging operations, potentially reducing recruitment to adult stocks. Worsening turbidity may have also contributed to declines in B. muricatum in other regions. For instance, in Roviana Lagoon, Western Solomon Islands, a small scale commercial B. muricatum fishery that was highly productive in the 1980s had collapsed by 2014 (Hamilton et al., 2016), a period during which water clarity declined in the lagoon due to intensification of logging (Halpern et al., 2013). The Roviana fishery may have suffered from the cumulative impacts of unstainable levels of fishing and the loss of recruitment habitat as a consequence of logging. Logging may represent a significant threat to near-shore coral reef fish and the fisheries that depend on them. For developing nations like Solomon Islands that are resource rich but cash poor, commercial logging provides a short-term source of revenue for customary landowners (Hviding, 2015). Yet high levels of corruption and lack of enforcement in the logging sector (Allen and Porter, 2016) means that

tion than other reef structures (Eggelston, 1995; Almany, 2004). Thus, the vulnerability of reef fish populations to loss of near shore recruitment habitats may be a general phenomenon. The particular pattern of recruitment in B. muricatum, with juveniles restricted to inshore Acropora dominated reefs appears to be consistent over geographic spatial scales. At Cocos Keeling Island juvenile B. muricatum were restricted to inshore sheltered lagoonal reefs adjacent to mangrove systems, and mature adults were only located on the outer reef crest and slope habitats of exposed reefs (JH Choat, personal observations). Furthermore, unfished geographies that do not support lagoonal environments have low abundances of B. muricatum (Hamilton and Choat, 2012). It appears that the specific settlement and juvenile habitat requirements of B. muricatum limit its abundance patterns at regional scales; and the loss of these habitats from climate change or land based impacts will almost certainly introduce a bottleneck to the recruitment dynamics of local populations (DeMartini et al., 2010). Analyses of the relationship between logging and juvenile abundance indicated a weaker habitat effect and a stronger direct effect of logging on B. muricatum presence. The indirect effect of logging related to the loss of branching coral, habitats that are likely to disappear quickly under elevated and prolonged sedimentation loads (Wilson et al., 2006). However, while B. muricatum abundance was predicted by coral cover alone, this relationship was weaker than when a direct effect of logging was included in the path model. The relatively weak relationship between coral cover and juvenile abundance may indicate that B. muricatum recruitment is hindered at extremely high coral cover sites (> 80%) because availability of algal food is low. Further, juvenile abundance will also depend on larval supply and post-recruitment processes, like predation (Almany, 2004) and such processes may create noise in the relationships between coral cover and abundance. Further sampling sites and quantification of the area of micro-habitats at sites (branching corals associated with damselfish gardens) would be

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Acknowledgements

best industry practices are not followed, premature re-entry harvesting is excessive and large volumes of sediment are allowed to run off into nearshore marine areas. Compounding this issue is the fact that royalty payments are made for each log pond that is built, so local landowners are often willing to let companies build multiple log ponds in a small geographical area, as opposed to insisting that they construct proper roads and build fewer log ponds in less ecologically sensitive locations. Establishing clear links between poor land based practices and the degradation of marine habitats is critical for convincing customary landowners of the need to prevent commercial logging in ecologically sensitive areas or, at a minimum, demand that logging companies follow best industry practices. In the Kia district we worked closely with numerous local fishers while researching the B. muricatum fishery (Hamilton et al., 2016), and the wider community was well informed on the results of this research. These factors, coupled with the fact that our study was conducted at a spatial scale relevant to local management, has resulted in a growing appreciation among customary land owners of Barora Faa over the importance of preserving the remaining B. muricatum nursery habitat that fringes this unlogged island. As a consequence of this several applications to commercially log Barora Faa have been declined in the past three years, and a logging operation that commenced at most western tip of Barora Faa in 2015 was quickly halted by customary owners who did not support the initiative, with the high court subsequently ruling that this operation was illegal and could not continue. While the future of the forests and nearshore nursery grounds of Barora Faa remains unknown, one thing appears certain. For the coastal Solomon Islanders who live a subsistence based lifestyle, the financial benefits they receive from logging come at a heavy price to the ecosystem services upon which they depend. Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.biocon.2017.04.024.

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Ethics statement The study adhered to the legal and ethical requirements of Solomon Islands. All fieldwork was carried out with approval from the Ministry of Fisheries and Marine Resource and the Ministry of Environment, Climate Change, Disaster and Meteorology Honiara, Solomon Islands. Access to the study area for research purposes was permitted by the Kia House of Chiefs. Data accessibility The datasets supporting this article have been uploaded as part of the Electronic supplementary material. Competing interests We have no competing interests. Authors' contributions RH, GA and JP designed and coordinated the study and collected field data. NP provided GIS support for this study and CB carried out the statistical analyses. RH, CB, JC and GA wrote the manuscript. All authors gave final approval for publication. Funding statement This research was supported in part by the Science for Nature and People Partnership, a collaboration of The Nature Conservancy, the Wildlife Conservation Society and the National Center for Ecological Analysis and Synthesis. 279



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