Live Reef Research Articles

The half-life of cyanide in the blood of the marine fish, Amphiprion clarkii after cyanide exposure

Cyanide fishing continues to be used in the Indo-Pacific region to capture live reef fish for use by the live fish food and marine aquarium trades. The deliberate release of this broad-spectrum poison in reef environments is one of many anthropogenic threats to coral reefs today. Although this capture method is illegal in most countries, regulating its use is challenging due to the difficulty in determining whether a fish was captured using cyanide. A reliable method to test if marine fish have been caught using cyanide has long been the goal of the marine aquarium trade, but to date no test has been validated on fish with known cyanide (CN) exposure. Additionally, there are little to no toxicokinetic data on CN metabolism following CN exposure for marine fish. In this study, we exposed 38 specimens of Amphiprion clarkii to cyanide (50 ppm for 45 s) and measured the concentration of cyanide in their blood over time to characterize the detoxification process. CN was isolated from the blood by microdiffusion and derivatized to the highly fluorescent ẞ-isoindole and then quantified by HPLC. The half-life of cyanide in the blood of the marine fish A. clarkii was found to be 3.1 ± 2.0 hrs. CN levels were seen to be slightly above control levels 1 day post exposure and below control levels 3 days post exposure suggesting that any test for CN exposure by measuring cyanide must be conducted soon after exposure. To our knowledge, this is the first direct measurement of cyanide in the blood of a marine fish following CN exposure.

Documenting Loss and Fragmentation of Intertidal Oyster (Crassostrea virginica) Reefs in a Subtropical Estuary

Intertidal reefs of Crassostrea virginica (eastern oyster) provide ecologically valuable habitat in estuaries along the Atlantic coast of North America. In Mosquito Lagoon, a shallow-water estuary on the east coast of central Florida, USA, historical aerial imagery was used to document a 24% decline in the live C. virginica reef area between 1943 and 2009. Using 2021 imagery, every living and dead reef in the same region was manually digitized to identify changes during the intervening 12 years. Positive impacts of C. virginica reef restoration that took place between 2007 and 2021 were also digitized to quantify long-term restoration impact. Natural, live C. virginica reef coverage throughout the system was found to have decreased by 50.6% between 2009 and 2021 and, thus, 62.6% between 1943 and 2021. This was attributed to reef fragmentation, reef footprint loss, boating activity, and mangrove expansion. Of the 2542 live reefs identified using 2009 imagery, 219 reefs fragmented, 988 reefs no longer had an identifiable footprint, and 598 reefs contained visible mangroves with non-continuous canopies. Conservatively, 63.6% of directly restored reef area was classified as living reef in 2021, and 74.5% of restoration projects were more than 50% live reef. Dead reef area decreased by 57.9% throughout the system. Understanding changes in C. virginica reef acreage, reef numbers, and mangrove expansion is essential for resource management, restoration practices, and tracking climate change impacts on publicly protected estuaries.

Live Fish Species Classification in Underwater Images by Using Convolutional Neural Networks Based on Incremental Learning with Knowledge Distillation Loss

Nowadays, underwater video systems are largely used by marine ecologists to study the biodiversity in underwater environments. These systems are non-destructive, do not perturb the environment and generate a large amount of visual data usable at any time. However, automatic video analysis requires efficient techniques of image processing due to the poor quality of underwater images and the challenging underwater environment. In this paper, we address live reef fish species classification in an unconstrained underwater environment. We propose using a deep Convolutional Neural Network (CNN) and training this network by using a new strategy based on incremental learning. This training strategy consists of training the CNN progressively by focusing at first on learning the difficult species well and then gradually learning the new species incrementally using knowledge distillation loss while keeping the high performances of the old species already learned. The proposed approach yields an accuracy of 81.83% on the LifeClef 2015 Fish benchmark dataset.

A Glimpse into Survival in the Banggi Region: Of Coastal Communities, Live Reef Fish Cages and Crocodile Lore

The Banggi region is home to coastal inhabitants that have a multitude of cultural beliefs and traditions, living a diaspora of marine biodiversity that is part of the Coral Triangle Region, thus rendering tremendous fisheries and eco-tourism potential. It is also a source region for Live Reef Fish (LRF) grown out in mariculture cages that contributes towards the multi-million dollar Asia Pacific commodity chain: the Live Reef Food Fish Trade (LRFFT). We attempt to provide a historical development of socio-demographics of the Banggi region along with an introduction to LRF cage initiatives and cultural beliefs regarding crocodiles to enhance understanding of the marginalized island communities and how they interact with the flourishing marine ecosystem around them. The Banggi region is a large portion of Tun Mustapha Park, a multiple use marine protected area (MPA) that falls under the jurisdiction of Sabah Parks.

The effectiveness of clove oil as an alternative to cyanide in catching coral trout, Plectropomus leopardus

Live reef fish are fish that have important economic value and have a very high selling value for export. Unfortunately, the process of catching reef fish still uses cyanide anesthetic, causing various problems, including damage to fish and coral reefs. As an alternative, it is recommended to use clove oil. However, it is necessary to analyze the effectiveness of clove oil as a cyanide alternative. This study aims to analyze the effectiveness of clove oil in coral trout (Plectropomus leopardus). This study consisted of aquarium preparation, preparation of test animals, observing fish behavior before and after exposure to clove oil and analyzing the effect of clove oil on the response of fish behavior. The experimental design used was a completely randomized design (CRD) consisting of 5 concentration treatments with 3 repetitions. Fish were put into the aquarium and then sprayed with several different concentrations of clove oil (20, 30, 40, 50, 60 ppm) until the fish passed out. Furthermore, it is analyzed based on the criteria recommended by Marking & Myer (1985). The ANOVA test results with an error rate of 5% (α = 0.05) indicated that the time to reach the affected stage in the coral trout did not differ significantly with different clove oil concentrations (P> 0.05). The same results were also obtained when the equilibrium was disturbed, when it reached the fainting stage and the recovery time of the coral trout, which showed that there was no significant difference in the different clove oil concentrations (P> 0.05). Based on the recommendation of Marking and Meyer (1985), all concentrations of clove oil used (20–60 ppm) have met the requirements as an ideal anesthetic, where the induction time is <15 minutes and the recovery time is <5 minutes. This shows that clove oil at a concentration of 20 - 60 ppm is effectively used in anesthetics for coral trout (Plectropomus leopardus).

Reef Conservation off the Hook: Can Market Interventions Make Coral Reef Fisheries More Sustainable?

The overexploitation of coral reef fisheries threatens the persistence of reef ecosystems and the livelihoods and food security of millions of people. Market-based initiatives to increase fisheries sustainability have been widely implemented in industrialized commodity fisheries, but the suitability of these initiatives for coral reef fisheries has not been systematically investigated. Here, we present a typology of market-based interventions and coral reef fisheries sectors and identity promising approaches for each fishery archetype. For high value, export-oriented reef fisheries that are highly unsustainable (live reef food fish and dried sea cucumbers), traditional regulatory efforts including trade restrictions will be most effective. For high-value, export-oriented fisheries for highly fecund invertebrates (lobsters and mollusks), certification and ratings efforts, fishery improvement projects, and sustainable purchasing commitments can improve fishing practices and increase fisher market access and revenue. For lower-value fisheries targeting species for domestic or regional consumption, sustainable purchasing commitments among local buyers, consumer awareness campaigns, and local certification and ratings schemes hold promise for shifting attitudes toward sustainability and increasing food security for local communities. Finally, fisher empowerment efforts including direct access to local markets and market information, training on improved post-harvest methods, and formation of fisher associations hold promise for increasing fisher incomes, reducing wasteful catch, increasing food security, and de-incentivizing unsustainable practices. Despite the potential of market-based interventions, specific approaches must be carefully tailored to the ecological and social reality of these systems, including the inherent unsustainability of commercial coral reef fisheries, the limited capacity for fisheries governance, the limited financial support of market-based initiatives, and the threatened status of coral reef ecosystems globally.

Ecosystems Approach to Fisheries Management (EAFM) assessment for grouper and snapper fisheries in Bontang, East Kalimantan, Indonesia

Groupers and snappers are two demersal fish groups that are currently experiencing heavy fishing pressure both for the live reef fish trade and as fresh or processed fisheries commodities across the Coral Triangle. The purpose of this study was to assess the status of grouper and snapper fisheries in the Bontang region, East Kalimantan, Indonesia using Ecosystems Approach to Fisheries Management (EAFM) indicators. The assessment followed the Indonesian EAFM Assessment Guidelines methodology, with 6 Domains (Fisheries Resources, Habitat and Ecosystems, Fishing Technology, Social, Economy, and Governance) and 32 indicators. Data were collected through a desk study and site visits including key informant interviews, direct observation and secondary data collection. With the exception of the Social Domain, at least one indicator in each Domain was in the Very Poor category, and three indicators were in the Poor category. Management policies and actions are needed to maintain the overall Good status and address the issues threatening sustainability.

Combining information on otolith morphometrics and larval connectivity models to infer stock structure of Plectropomus leopardus in the Philippines

The leopard coral grouper Plectropomus leopardus is a high-value fish species in the live reef fish for food trade (LRFFT), with stocks declining continually due to increasing market demands and unsustainable fishing practices. Managing this resource is difficult due to lack of biological information on local stocks. This paper utilized phenotypic- and model-based methods to discriminate stocks of P. leopardus in 3 LRFFT hubs in the Philippines (Taytay, Quezon, and Tawi-Tawi). Phenotypic variation among sites was assessed using shape descriptors and landmark data of otoliths, while patterns of connectivity were inferred from a dispersal model of coral grouper larvae. Inferences suggest (1) the presence of distinct phenotypic stocks and (2) limited larval connectivity among sites. There was an inconsistency with how otolith shape discriminated stocks. While shape descriptors identified Tawi-Tawi as a separate unit, landmark data differentiated Quezon from the other sites. This suggests that different processes may influence otolith shape, thereby presenting a caveat when using otolith morphometrics in stock discrimination. Meanwhile, the dispersal model showed that Quezon and Tawi-Tawi distribute larvae primarily to the West Philippine Sea and Celebes Sea, respectively. Although the model showed that Taytay supplies larvae to both Quezon and Tawi-Tawi, these connections were weak. Model inferences showing all sites as important larval sources to different reefs, coupled with the presence of distinct phenotypic stocks based on otolith shape, suggest that each LRFFT hub is an independent management unit. Thus, identifying key drivers of stock decline is crucial in developing site-specific fishery management approaches.

Distribution of Mangrove Red Snapper Lutjanus argentimaculatus in response to hydrodynamic condition at the reef patches of Lankayan, Sugud Islands Marine Conservation Area, Sabah, Malaysia

The species Lutjanus argentimaculatus is a prized food-fish in the tropical and subtropical fisheries, as well as the aquaculture industry. This study investigated the distribution of L. argentimaculatus at three patch reefs of Lankayan Island, within the Sugud Islands Marine Conservation Area. Fish surveys of this species were conducted 12 times at each of the selected patch reefs, from August 2016 until March 2017. In addition to taking underwater video footages, hydrodynamic parameters, i.e. water current direction and current speed were recorded during each survey. The distribution patterns of the fish were then plotted against these parameters to determine any correlation, in response to these parameters. As a result, we found a significant relationship between the current direction and the position of L. argentimaculatus at the reef where the schoolings were found to occur. We found that regardless of the current speed, the schools of L. argentimaculatus were always present at the reef slope facing the incoming current. This finding is important for the management and conservation of this species, which is a targeted species in the Live Reef Fish Food Trade (LRFFT), and is useful for the manager of a Marine Protected Area (MPA) in general. This finding is also important as it provides useful insights into the ecology of Lutjanus spp.

In situ growth and bioerosion rates of Lophelia pertusa in a Norwegian fjord and open shelf cold-water coral habitat.

Coral reef resilience depends on the balance between carbonate precipitation, leading to reef growth, and carbonate degradation, for example, through bioerosion. Changes in environmental conditions are likely to affect the two processes differently, thereby shifting the balance between reef growth and degradation. In cold-water corals estimates of accretion-erosion processes in their natural habitat are scarce and solely live coral growth rates were studied with regard to future environmental changes in the laboratory so far, limiting our ability to assess the potential of cold-water coral reef ecosystems to cope with environmental changes. In the present study, growth rates of the two predominant colour morphotypes of live Lophelia pertusa as well as bioerosion rates of dead coral framework were assessed in different environmental settings in Norwegian cold-water coral reefs in a 1-year in situ experiment. Net growth (in weight gain and linear extension) of live L. pertusa was in the lower range of previous estimates and did not significantly differ between inshore (fjord) and offshore (open shelf) habitats. However, slightly higher net growth rates were obtained inshore. Bioerosion rates were significantly higher on-reef in the fjord compared to off-reef deployments in- and offshore. Besides, on-reef coral fragments yielded a broader range of individual growth and bioerosion rates, indicating higher turnover in live reef structures than off-reef with regard to accretion–bioerosion processes. Moreover, if the higher variation in growth rates represents a greater variance in (genetic) adaptations to natural environmental variability in the fjord, inshore reefs could possibly benefit under future ocean change compared to offshore reefs. Although not significantly different due to high variances between replicates, growth rates of orange branches were consistently higher at all sites, while mortality was statistically significantly lower, potentially indicating higher stress-resistance than the less pigmented white phenotype. Comparing the here measured rates of net accretion of live corals (regardless of colour morphotype) with net erosion of dead coral framework gives a first estimate of the dimensions of both processes in natural cold-water coral habitats, indicating that calcium carbonate loss through bioerosion amounts to one fifth to one sixth of the production rates by coral calcification (disregarding accretion processes of other organisms and proportion of live and dead coral framework in a reef). With regard to likely accelerating bioerosion and diminishing growth rates of corals under ocean acidification, the balance of reef accretion and degradation may be shifted towards higher biogenic dissolution in the future.

Reproductive Biology of Three Important Threatened/Near-Threatened Groupers (Plectropomus leopardus, Epinephelus polyphekadion and Plectropomus areolatus) in Eastern Indonesia and Implications for Management.

Simple SummaryIndonesia needs basic data on the reproductive dynamics of economically important fishery species, including groupers, in order to support sustainable fisheries management. Data from the histological examination of grouper gonad samples were combined with data from: participatory mapping and interviews with fishermen, monitoring data from known spawning aggregation sites, and analyzed descriptively to provide basic data on the size at first maturity and seasonal reproductive patterns of three economically important groupers. We suggest management measures including size limits, temporal spatial closures, and a trading ban during the peak spawning season (November–December).The three grouper species most heavily fished for the live reef fish trade (LRFT) in Indonesia are Plectopomus leopardus (greatest catch volume), and two species classified as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List: Plectropomus areolatus and Epinephelus polyphekadion. Understanding the reproductive biology of these fishes is essential for sustainable management, but relevant data are limited. This study aimed to determine reproductive dynamics, so as to inform management measures to maintain the reproductive capacity of these groupers. Grouper gonad samples collected from fish caught for the LRFT were analyzed histologically. Data were also collected from participatory mapping and interviews with fishermen, and underwater monitoring of three known spawning aggregation sites in the Wakatobi National Park, Eastern Indonesia. Based on observed gonad development, the respective lengths and weights at first maturity were: 37.7 cm and 759 g (P. leopardus); 36.65 cm and 771.2 g (P. areolatus); 36.95 cm and 889.9 g (E. polyphekadion). The mean weight of the groupers market-based sampled was higher than the size at first sexual maturity. Sex transition was observed in P. leopardus; sex reversal was not observed in E. polyphekadion, and the sex pattern of P. areolatus was unresolved. Based on the fisher surveys and spawning aggregation monitoring, spawning occurs around the new moon from September to April, with reproductive peaks in November and December. Fisheries management measures that are suggested to sustain grouper stocks include enforcing appropriate size limits, temporal spatial closures (spawning aggregation sites), and a trading ban during the peak spawning season (November–December).

Increasing survival and growth in larval leopard coral grouper (Plectropomus leopardus) using intensively cultured Parvocalanus crassirostris nauplii

AbstractLeopard coral grouper, Plectropomus leopardus are a heavily exploited, high‐value fish commonly found in the Asian live reef food fish trade. In past decades, many attempts at the mass culture of various grouper species have been undertaken; however, their small mouth gape at first feed has resulted in very low survival when using traditional live feeds such as rotifers. The use of wild caught or extensively cultured copepods has yielded potentially promising increases in survival and growth, but overall survival to the juvenile stage remains low, making mass culture currently impractical. The current study sought to build on past developments in grouper culture and recent advancements in copepod culture technology by observing how growth and survival were influenced by the addition of intensively cultured copepods to the early diet of P. leopardus larvae. Six tanks of larvae, three replicates per treatment, were fed either eggs and nauplii of the calanoid copepod Parvocalanus crassirostris, at a starting density of 5 mL−1, and the rotifer Brachionus rotundiformis, at a starting density of 10 mL−1, or were fed only B. rotundiformis, at a density of 15 mL−1, starting on the evening of 2 days post‐hatch (dph) and continuing until 9 dph. After this initial period, all larvae were fed the same diet of rotifers, Artemia, and dry feed until the cessation of the trial at 21 dph. Larvae fed P. crassirostris in addition to rotifers had a significantly higher survival, 9.9 versus 0.5%, than those fed only rotifers. Growth was also significantly enhanced in larvae offered copepods. Larvae only fed rotifers were, on average, 1.5 mm shorter at 21 dph than those that had been fed copepods. More rapid development and the earlier onset of flexion were also noted in the larvae that were offered copepods. The use of intensively cultured copepods, in this study, increased survival tenfold over previous studies, with P. leopardus larvae fed wild‐caught copepods. The application of intensively cultured copepods to the early diet of P. leopardus, along with future research to evaluate late‐stage mortality issues, may facilitate commercial production of this species.

Quantifying the rare: Baselines for the endangered Napoleon Wrasse, Cheilinus undulatus, and implications for conservation

Abstract The Napoleon wrasse, an endangered fish (Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II, 2004), is a valuable component of the Chinese live reef fish trade. Only Indonesia legally exports up to 2000 Napoleon fish annually, with each fish weighing between 1 and 3 kg. Information on natural abundance and fish sizes was required to determine sustainable export quotas. Hence, an underwater visual survey method, using GPS‐based multi‐kilometre transects, was tailored for this uncommon wide‐ranging fish. Transects totalling 430 km were run between 2005 and 2016 at nine locations. Six locations were resurveyed between six and nine years later, which was long enough to allow for recruitment and maturation. Fish density and sizes across locations were inversely related to fishing intensity, and densities increased significantly between surveys. Low density (0.04‐0.86 fish hectare‐1) and few adult‐sized fish were in heavily fished locations. Higher densities occurred (0.86‐4.0 fish hectare‐1) in lightly/unfished locations, where evidence of recruitment was also seen. Nowhere were many male-sized (&gt;1 m long) fish present. At Karas Is., where fishing ceased between surveys, clear sign of recovery was seen after 9 years. Comparison of survey data from 11 Indo‐Pacific countries indicated that in Indonesia adult densities were lower at comparable levels of fishing pressure than elsewhere. Densities of 5 fish hectare−1 or more are more typical of lightly fished or unfished areas across the Pacific, which is greater than the highest density of 4 fish hectare−1 noted in this study at Banda Islands. Low densities of the species, despite the presence of adult‐sized fish, in Bunaken Marine Park probably reflects the continuance of fishing both within and adjacent to the park. Conservation options include improved implementation of CITES regulations by Indonesia, through tighter export controls and the tagging of legally exported fish, the activation of the National Plan of Action, a temporary moratorium to restore reproductive capacity, and more marine protected areas.

Defining research priorities to detect live fish illegally collected using cyanide fishing in Indo-Pacific coral reefs

Indo-Pacific coral reefs face an unprecedented level of anthropogenic pressure. Cyanide fishing is a highly destructive method employed to capture live fish from Indo-Pacific coral reefs and supply the live fish food trade in Asia and the global marine aquarium trade. To allow the development and implementation of an effective and reliable testing platform to screen live reef fish for cyanide poisoning, without their sacrifice, and thus contribute to the ban of this practice from Indo-Pacific coral reefs, the following research topics must be urgently addressed: 1) selection of a suitable model species; 2) standardization of experimental methodologies; 3) exclude the possibility that the target compound(s) being monitored to detect live reef fish illegally collected using cyanide originate from other sources than cyanide poisoning; 4) clarification of the excretion physiology and cyanide pharmacokinetics in marine fish; and 5) evaluate interspecific differences in excretion physiology and cyanide pharmacokinetics in marine fish.

Social Networks and the Live Reef Food Fish Trade: Examining Sustainability

-

Correction: Can excreted thiocyanate be used to detect cyanide exposure in live reef fish?

[This corrects the article DOI: 10.1371/journal.pone.0196841.].

Patterns of gene expression in larvae of the giant grouper.

The giant grouper Epinephelus lanceolatus (Bloch 1790) is the largest bony fish found on coral reefs, achieving lengths of over 2 m. It has delicious flesh that is highly prized by the live reef fish trade. Consequently, declining wild populations have been listed as Vulnerable by IUCN. There is now aquaculture of E. lanceolatus but, as is often the case for marine fishes, larval feeding is a major production bottleneck. In particular, knowing how the digestive system develops and how this might determine the feed that larvae can digest to grow satisfactorily. In this issue, Anderson et al. (2018) used a transcriptomic approach to explore molecular processes that underpin development of appetite, feeding and digestion in E. lanceolatus larvae. They focussed on the first two weeks of life, a critical period for larval husbandry during which the larvae first open their mouth and start exogenous feeding. Because transcriptomics typically yield a very large quantity of information, the challenge is to reveal patterns. The authors used Self Organising Maps to hone in on genes that contribute to specific developmental milestones. They developed a conceptual model to show patterns of expression of transcripts in relation to major developmental stages, such as mouth-opening, onset of exogenous feeding, swim bladder development. There were clear trends for digestive enzyme transcripts, which tended to increase their expression in concert with mouth-opening and onset of exogenous feeding. Gene expression for various appetite-regulating factors was highly variable although, in some cases, this could be linked to important developmental milestones. Although such studies are inductive, they provide an essential knowledge base for development of targeted hypothesis-driven research. A major objective would be to find means of improving growth and survival of larvae without having to rely on feeding with copepods, which are expensive to produce in large quantities. Such improvements in methods for larval husbandry, in the farming of this highly-prized species, will take pressure off vulnerable wild stocks. The authors commented that Self Organising Maps can be applied to any project generating high volumes of multi-dimensional data, and are especially useful for time-course studies and pattern visualisation. As such, fish biologists are able to use this approach to more easily hone in on genes that contribute to specific developmental milestones, phenotype, mortality event, whose expression changes in response to particular stimuli.

Assessing condition and ecological role of deep-water biogenic habitats: Glass sponge reefs in the Salish Sea

Biogenic habitats play important roles in shallow-water ecosystems, but their roles in deeper waters are less well-studied. We quantitatively assessed 19 glass sponge reefs in the Salish Sea for live reef-building sponge cover and biodiversity, explored potential drivers behind variation observed among reefs, and quantified individual and collective roles the reefs play in filtration and carbon removal. The reefs support diverse and abundant communities of invertebrates and fish, with 115 unique taxonomic groups observed. Sponge cover varied widely between reefs: percent live reef-building sponge cover ranged from 0.2 to 17.5% and proportion of live reef habitat category ranged from 0.2 to 92%. These differences were predominantly driven by the seabed terrain characteristics such as seafloor rugosity, curvature, and depth; human pressure measures explored in this study − density of anthropogenic objects and fishing footprint over the past 17 years – did not mask the natural influence of seabed terrain. The difference in sponge cover between the reefs led to wide variation in ecosystem function with individual reefs processing between 465 and 47,300 L/m2 per day. Collectively, each day the 19 reefs filter 1.04 × 1011 L of water which corresponds to 1% of the total water volume in Strait of Georgia and Howe Sound combined. The reefs remove up to 1 g of carbon per m2 per day, comparable to carbon sequestration rates reported for terrestrial old growth forests and to “blue carbon” sequestration rates by marine vegetation. Implications for sponge reef conservation and monitoring are discussed.

Can excreted thiocyanate be used to detect cyanide exposure in live reef fish?

Cyanide fishing, where a solution of sodium or potassium cyanide is used to stun reef fish for easy capture for the marine aquarium and live fish food trades, continues to be pervasive despite being illegal in many countries and destructive to coral reef ecosystems. Currently, there is no easy, reliable and universally accepted method to detect if a fish has been exposed to cyanide during the capture process. A promising non-invasive technique for detecting thiocyanate ions, the metabolic byproduct excreted by exposed fish, has been reported in the literature. In an effort to validate this method, four cyanide exposure studies on Amphiprion ocellaris (common clownfish) were carried out over three years. Fish were either exposed to the same (25 ppm) or twice the concentration (50 ppm) as the previsouly published method. Over 100 water samples of fish exposed to cyanide were analyzed by reverse phase HPLC with a C30 column treated with polyethylene glycol and UV detector operating at 220 nm. No thiocyanate was detected beyond the analytical standards and positive controls prepared in seawater. As an alternate means of detecting thiocyanate, water samples and thiocyanate standards from these exposures were derivatized with monobromobimane (MBB) for LC-MS/MS analysis. Thiocyanate was detected in standards with concentrations as low as 0.6 μg/L and quantified to 1 μg/L, but thiocyanate could not be detected in any of the water samples from fish exposed to cyanide with this method either, confirming the HPLC results. Further, we calculated both the mass balance of thiocyanate and the resultant plausible dosage of cyanide from the data reported in the previously published method. These calculations, along with the known lethal dosage of cyanide, further suggests that the detection of thiocyanate in aquarium water is not a viable method for assessing fish exposure to cyanide.

Disentangling economic, social, and environmental drivers of coral-reef fish trade in Micronesia

Abstract Fisheries represent a fundamental resource linking social and ecological systems. Yet, unsustainable fishing regimes prevail across many tropical regions as a result of growing consumer demand and market expansion. Using the extensive reef-fish trade between Chuuk and Guam (Micronesia) as a case study, we examined 12 years of commercial reef-fish export data to capture both inter-annual and intra-annual trends. Reef-fish exports from Chuuk increased steadily between 2003 and 2010 fueled by increasing demand on Guam, but declined sharply from 2010 to 2014 as export costs grew and profit margins were reduced. Intra-annual examinations furthered that low winds and new moon periods were the strongest drivers of daily exports during the initial years of the study, but the governmental disbursement of food-stamp allowances on Guam became the strongest driver in later years when profit margins were lower. Seasonal cycles were also influential, as exports within each year peaked during the Catholic lent season. In sum, the Chuuk-Guam reef-fish trade industry became increasingly dependent on opportunistic demand from Guam, while environmental regimes evolved to become secondary drivers of export volume. The ability to meet foreign demand may suggest a sustainable fishery in Chuuk, however, mounting evidence suggests that consistent supply to international markets masks growing, unsustainable harvesting regimes. Dwindling profits may lead to instability in Guam’s fresh reef-fish trade industry, and also suggested uncertain futures for Chuuk fishers, Guam retailers, and a society dependent on healthy protein. We last compared the sequential expansion of Guam’s reef-fish acquisition footprint across the Indo-Pacific with expansions reported for the Hong Kong live reef food fish trade industry, highlighting the growing impacts of population centers on small-scale coral-reef fisheries as markets globalize.