Understanding the ontogenetic habitat linkages of sharks is important for conservation and managi... more Understanding the ontogenetic habitat linkages of sharks is important for conservation and managing human interactions. We used acoustic telemetry, catch data, elemental and stable isotope signatures and dietary analyses to investigate ontogenetic habitat use in south-east Queensland, Australia, by the bull shark Carcharhinus leucas, a IUCN 'near-threatened' species that is implicated in many shark attacks on humans in urban estuaries. Sequential analyses for d 15 N and d 13 C of vertebrae from five adult C. leucas and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for elemental composition from 23 C. leucas, including a pregnant female, were also used to trace ontogenetic habitat dependence. Acoustic telemetry indicated large juvenile and subadult C. leucas remained in estuarine habitats. d 15 N values across shark vertebrae showed an ontogenetic shift in diet with total length (TL), confirmed by stomach contents. LA-ICPMS data reflected the ontogenetic movements of C. leucas from natal habitats. Differences among adults were gender related. Shifts in habitat use by subadults were correlated with a sigmoidal d 13 C relationship with TL. C. leucas have a multipartite, stage-specific dependency in their transition between habitats along the freshwaterestuarine-marine continuum, making them particularly susceptible to the habitat alteration that is occurring globally.
Australia A B S T R A C T Many commercially important fish species use coastal marine environment... more Australia A B S T R A C T Many commercially important fish species use coastal marine environments such as mangroves, tidal flats and seagrass beds as nurseries or breeding grounds. The ecological importance of spatially connected habitats to conservation is well established for terrestrial environments. However, few studies have applied spatial metrics, including measures of structural connectivity to marine environments. We examined the relationship between catch-per-unit-effort for commercially caught species and the spatial patterning of mapped benthic habitat types along the coast of Queensland, Australia in their dominant fisheries (trawl, line, net or pot fisheries). We quantified the composition and spatial configuration of seascapes and calculated coastline length, number of estuaries, river length and geographical latitude using 12 metrics within ninety 30-nautical-mile grid cells, which supported inshore fish catch data from 21 species groups. Multiple regression analysis and non-metric multidimensional scaling plots indicated that ecological linkages may exist between geomorphic coastal features and nearshore fisheries production for a number of species groups. Connectivity indices for mangroves, salt marsh and channels explained the largest proportion (30-70%), suggesting the importance of connected tidal wetlands for fisheries.
Analytical and Bioanalytical Chemistry, Jan 31, 2009
Investigation into persistent organic pollutants (POPs) in sea turtles is an important area of co... more Investigation into persistent organic pollutants (POPs) in sea turtles is an important area of conservation research due to the harmful effects of these chemicals. However, the analysis of POPs in the green sea turtle (Chelonia mydas) has been limited by methods with relatively high limits of detection and high costs associated with multiple sample injections into complex arrangements of analytical equipment. The present study aimed to develop a method that could detect a large number of POPs in the blood, eggs and tissue of C. mydas at trace concentrations. A gas chromatography with tandem mass spectrometry (GC-MS/MS) method was developed that could report 125 POP compounds to a limit of detection of <35 pg g −1 using a single sample injection. The recoveries of internal standards ranged from 30% to 96%, and the standard reference materials were reported to within 70% of the certified values. The coefficient of variation of ten replicates of pooled egg sample was <20% for all compounds, indicating low within-run variation. This GC-MS/MS method is an improvement of previous methods for analysing POPs in C. mydas in that more compounds can be reported at lower concentrations and the accuracy and precision of the method are sound. This is particularly important for C. mydas as they occupy a low trophic level and have lower concentrations of POPs. This method is also simple to set up, and there are minimal differences in sample preparation for the different tissue types.
Hammerhead sharks have experienced a drastic global reduction in abundance, yet limited data exis... more Hammerhead sharks have experienced a drastic global reduction in abundance, yet limited data exist on their general biology and population structure. We use generalised linear models (GLMs) to analyse historical mesh net and drumline catches (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) of Sphyrna lewini from the Queensland Shark Control Program (QSCP), which covers 10 locations on the north-east coast of Australia. Results show a significant decline in S. lewini female total length over the study period and a significant increase in annual CPUE on the Gold Coast. Sexual segregation was found in Cairns, where S. lewini males were most abundant. A positive linear relationship was found between maternal total length and litter size. Birthsize embryos were found in most months. However, normal birth size (0.50 m) embryos were found in pregnant females most often during spring and summer. Mesh nets were more selective for smaller S. lewini than drumlines. It is recognised that species selectivity of other, more potentially dangerous shark species varies between gear types, but replacement of mesh nets with drumlines would reduce the catch of smaller individuals of S. lewini and assist in their conservation.
Nitrogen stable isotope values (␦ 15 N) have commonly been used as a qualitative indicator of cat... more Nitrogen stable isotope values (␦ 15 N) have commonly been used as a qualitative indicator of catchment urbanization in estuaries, but no quantitative relationship has to date been established between ␦ 15 N and degree of urbanization. We sampled five species of common estuarine fish (Mugil cephalus, Acan-thopagrus australis, Sillago ciliata, Gerres subfasciatus and Herklotsichthys castelnaui) of different trophic levels from six estuaries in Southeast Queensland, Australia, to test if a quantitative relationship exists between fish ␦ 15 N and urbanization in the catchment. Degree of urbanization (urban %) in the catchment adjacent to the tidal estuary was measured using polygons constructed in Google Earth images, and verified using data from the detailed Queensland Land Use Mapping Project (QLUMP). Significant linear relationships exist between fish ␦ 15 N and urban % in most cases irrespective of the section of the estuary (upper, middle and lower) where the fish were caught, wit...
Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pe... more Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), have a wide range of toxic effects on humans and wildlife, and have been reported in a number of endangered sea turtle populations. The present study screened for POPs in a green sea turtle Chelonia mydas population in Peninsular Malaysia and investigated the maternal transfer and effects of POPs on embryonic development. At the Ma'Daerah Turtle Sanctuary, blood, eggs and hatchling blood were collected from 11 nesting female C. mydas. Samples were analysed for 83 PCBs, 23 OCPs and 19 PBDEs using gas chromatography with tandem mass spectrometry. The chemical profiles of eggs from individual turtles were significantly different, indicating variable contaminant uptake during foraging. There was evidence of maternal transfer of POPs to eggs and hatchlings, with significant correlations in sum of PCBs (ΣPCB), sum of PBDEs (ΣPBDE), γ-hexachlorocyclohexane (γ-HCH), trans-chlordane and mirex concentrations between maternal blood and eggs (p < 0.05, R 2 < 0.71), between eggs and hatchling blood (p < 0.05, R 2 < 0.83), and between maternal and hatchling blood (p < 0.05, R 2 < 0.61). In addition, there was congener-specific transfer of PCBs with less lipophilic congeners (e.g. PCB 99) more readily transferred to hatchlings than the more lipophilic congeners (e.g. PCBs 180 + 193). There was also a significant correlation between increasing egg POP concentration and decreasing hatchling mass:length ratio. POPs may therefore have subtle effects on the development of C. mydas eggs, which may compromise offshore dispersal and predator avoidance.
The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in t... more The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in the Indo-West-Pacific. It has a complex life cycle with a dispersing larvae phase, and benthic juveniles and adults. The former are stenohaline depending on high-salinity conditions to survive, whereas the latter are physiologically well adapted to changing temperatures and salinities, conditions that typically occur in mangrove habitats. Movement and habitat use of large juveniles and adults are well studied, and these life stages are known to utilize and move between various habitats within the mangrove ecosystem: intertidal flats as well as subtidal channels and flats. Females undertake long movements from brackish inshore waters to waters with oceanic conditions for spawning. Sensory abilities-of early stages and adult stageshave hardly been studied, and little is known about larval and early benthic stages in the wild. Summarizing, the literature revealed substantial gaps in the understanding of the spatiotemporal dynamics of the different life stages and of the clues that trigger recruitment, movement, and other behavior. This is the first comprehensive review on the life history, movement patterns, habitat use, and systemic role of S. serrata with emphasis on the respective life stages and geographic differences. We emphasize the need for further research into these processes as a basis for the sustainable management and conservation of this species.
Context. Many green sea turtle (Chelonia mydas) populations are declining worldwide owing to thei... more Context. Many green sea turtle (Chelonia mydas) populations are declining worldwide owing to their susceptibility to human impacts in the marine environment. Identifying the habitats used throughout different lifecycle stages is therefore important for managing the interactions between turtles and humans.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2015
The sesarmid crab Parasesarma erythodactyla consumes large amounts of mangrove leaf litter but it... more The sesarmid crab Parasesarma erythodactyla consumes large amounts of mangrove leaf litter but its biochemical capacity for cellulose digestion is poorly known. We demonstrate the presence of endo-β-1,4-glucanase, β-glucosidase and total cellulase activities in the digestive juice of this crab. The highest total cellulase activity was observed at mildly acidic pH (5 to 6) and temperature between 30 and 50°C. A 1752 bp cDNA containing an open reading frame of 1386 bp encoding a putative endo-β-1,4-glucanase (EG) of 461 amino acids was identified in the crab's hepatopancreas using polymerase chain reaction (PCR), cloning and sequencing techniques. P. erythodactyla endo-β-1,4-glucanase (PeEG) contains a glycosyl hydrolase family 9 (GHF9) catalytic domain with all catalytically important residues conserved, and shows high sequence identity to GHF9 EGs reported from other arthropods. The endogenous origin of PeEG was confirmed by PCR amplification of a~1.5 kb DNA fragment, containing a phase 1 intron flanked by two exon sequences identical to the cDNA, from genomic DNA isolated from the crab's muscle tissue. PeEG encoding cDNA is the first endogenous EG sequence reported from the brachyuran crabs. Using degenerate primers, we also isolated 204 bp cDNA fragments with sequences affiliated to EG from the hepatopancreas of eight other mangrove crabs of the Sesarmidae (Neosarmatium trispinosum and Sesarmoides borneensis), Macrophthalmidae (Ilyograpsus daviei, Australoplax tridentata, and Macrophthalmus setosus), Varunidae (Pseudohelice subquadrata), Heloeciidae (Heloecius cordiformis), and Ocypodidae (Uca perplexa) families, suggesting that endogenous cellulase production may be a common characteristic among the detritivorous mangrove crabs.
1. Structural complexity, that is, spatial patterns of structural 'units of interest', is one of ... more 1. Structural complexity, that is, spatial patterns of structural 'units of interest', is one of the most fundamental drivers in habitat use of animals and other functions of habitats. Assessment of habitat structural complexity (e.g. mangrove root complexity) and its ecological implications (e.g. mangroves as nursery sites) has, however, been hampered by the lack of satisfactory methods for realistically measuring and analysing field habitat structure. 2. We demonstrate a simple low-cost approach comprising an RGB_D scanning sensor (Kinect), free and readily accessible software (Meshlab, Matlab (or Octave), Qubicle Constructor and Voxeliser) and fractal dimension to measure mangrove root structure and complexity at spatial scales relevant to juvenile fish use of the habitat. The cube-counting method was used for three-dimensional characterisation of fractal dimensions of space around aerial roots of mangroves from a 'fish point of view'. Space-fish relationship under different ecological situations was assessed by simulating a falling tide and using different rectangular prisms to represent varying fish allometries utilizing the space. 3. Fractal dimension (FD) of space around roots decreased with decreasing height of the 'object' mimicking a falling tide. The same root system may therefore look more complex to aquatic animals as the water level decreases. We also assessed the variation in FD responding to manipulation of the density and arrangement of objects (pneumatophores). Difference in FD was generally small, due attention to replication is necessary for comparisons of habitat structural complexity using this metric. 4. This simple low-cost approach will enable field measurements of habitat structure at spatial scales relevant to its influence on habitat use and animal behaviour, as well as allowing realistic replication of field structure for laboratory-based experiments.
In whole-sediment toxicity tests employing metal-spiked sediment, pH is a crucial determinant of ... more In whole-sediment toxicity tests employing metal-spiked sediment, pH is a crucial determinant of sediment geochemistry, sediment-porewater metal partitioning and metal bioavailability to benthic organisms. Small pH changes in metal-spiked sediment may therefore have important implications for toxicity to organisms. The present study evaluated the effect of small-scale pH changes (pH 6.6, 7.2, 7.6) in Cu-spiked sediment on metal bioavailability and subsequent organism response. Variation of pH produced distinct changes in sediment geochemistry. Increasing pH from 6.6 to 7.6 resulted in lower redox potential, greater acid volatile sulfide (AVS) formation, and lower partitioning of Cu, Fe and
Background: Despite accelerated global population declines due to targeted and illegal fishing pr... more Background: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN 'Near-threatened' species -one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species.
Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green tur... more Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green turtle (Chelonia mydas) populations worldwide. However, due to ethical considerations, these studies have generally been on tissues from deceased and stranded animals. The purpose of this study was to investigate the use of blood samples to estimate the tissue contamination of live C. mydas populations. This study analysed 125 POP compounds and eight heavy metals in the blood, liver, kidney and muscle of 16 C. mydas from the Sea World Sea Turtle Rehabilitation Program, Gold Coast, Australia. Strong correlations were observed between blood and tissue concentrations for a number of POPs and metals. Furthermore, these correlations were observed over large ranges of turtle size, sex and condition. These results indicate that blood samples are a reliable non-lethal method for predicting chemical contamination in C. mydas.
Past studies on the size and structure of the chelipeds of predatory crabs have focused mainly on... more Past studies on the size and structure of the chelipeds of predatory crabs have focused mainly on their use in foraging. This study of the morphometrics of the chelipeds of 2 predatory portunid crabs, Carcinus maenas L. and Liocarcinus holsatus (Fabricius) and the use of these structures in feeding, reproduction and agonistic interactions, provides further support to the view that the evolution of crab chelae is not driven by feeding requirements alone. Although individuals with larger chelipeds can feed on a wider range of prey species and sizes, the proportion of hard-bodled prey in the natural diet of C. maenas was small. Bigger chelae, however, confer selective advantages by increasing success in mate competition and intraspecific agonistic interactions. Field collections of mating pairs of C. maenas indicated that > 90 % of mating males had chelae that were above the average size for the male population as a whole. Agonistic encounter experiments, in which crab models (constructed from empty moults) with chelae that were either larger than or smaller than the mean population values were presented to conspecifics suggested that cheliped size and meral spread was probably more important than overall body size in determining the response pattern of the subjects. Maintenance costs for chelipeds in L. holsatus estimated by respirometry were not significantly different from other body tissues as oxygen uptake rate could be predicted solely from dry tissue weight. Moreover, the rate of oxygen uptake was independent of the proportion of the total body weight that could be attributed to the chelipeds.
Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pe... more Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), have a wide range of toxic effects on humans and wildlife, and have been reported in a number of endangered sea turtle populations. The present study screened for POPs in a green sea turtle Chelonia mydas population in Peninsular Malaysia and investigated the maternal transfer and effects of POPs on embryonic development. At the Ma'Daerah Turtle Sanctuary, blood, eggs and hatchling blood were collected from 11 nesting female C. mydas. Samples were analysed for 83 PCBs, 23 OCPs and 19 PBDEs using gas chromatography with tandem mass spectrometry. The chemical profiles of eggs from individual turtles were significantly different, indicating variable contaminant uptake during foraging. There was evidence of maternal transfer of POPs to eggs and hatchlings, with significant correlations in sum of PCBs (ΣPCB), sum of PBDEs (ΣPBDE), γ-hexachlorocyclohexane (γ-HCH), trans-chlordane and mirex concentrations between maternal blood and eggs (p < 0.05, R 2 < 0.71), between eggs and hatchling blood (p < 0.05, R 2 < 0.83), and between maternal and hatchling blood (p < 0.05, R 2 < 0.61). In addition, there was congener-specific transfer of PCBs with less lipophilic congeners (e.g. PCB 99) more readily transferred to hatchlings than the more lipophilic congeners (e.g. PCBs 180 + 193). There was also a significant correlation between increasing egg POP concentration and decreasing hatchling mass:length ratio. POPs may therefore have subtle effects on the development of C. mydas eggs, which may compromise offshore dispersal and predator avoidance.
Fatty acid compositions of the leaves of six species of mangroves were studied to ascertain their... more Fatty acid compositions of the leaves of six species of mangroves were studied to ascertain their use as biomarkers for determining the fate of mangrove organic matter in the habitat and as taxonomic tool. Mangrove leaves were collected from three locations in the western PaciWc Ocean: Moreton Bay (MB) (Australia), Hong Kong (China) and Okinawa (Japan). In MB, samples were collected from two sites separated by 15 km: Logan River Estuary (LRE) and Jabiru Island. In addition, along the LRE, leaves were collected from Wve stations at »2-3 km apart. Results show that the analysis of the entire fatty acid proWles of the mangrove leaves is a promising taxonomic tool as the proWles of most species were suYciently diVerent to be separated in an non-metric multidimensional scaling plot. In addition, geographically separated populations of the same species could also be identiWed by their fatty acid proWles. In most cases, two non-ubiquitous groups of fatty acids dominated in the mangrove leaves: the polyunsaturated 18:2 6 and 18:3 3 and the long chain fatty acids (¸24:0). With respect to the relative contributions of these fatty acids, three groups of species were identiWed, in which one or both groups of fatty acids may potentially be used as markers of the mangrove organic matter in the estuarine environment.
Understanding the ontogenetic habitat linkages of sharks is important for conservation and managi... more Understanding the ontogenetic habitat linkages of sharks is important for conservation and managing human interactions. We used acoustic telemetry, catch data, elemental and stable isotope signatures and dietary analyses to investigate ontogenetic habitat use in south-east Queensland, Australia, by the bull shark Carcharhinus leucas, a IUCN 'near-threatened' species that is implicated in many shark attacks on humans in urban estuaries. Sequential analyses for d 15 N and d 13 C of vertebrae from five adult C. leucas and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for elemental composition from 23 C. leucas, including a pregnant female, were also used to trace ontogenetic habitat dependence. Acoustic telemetry indicated large juvenile and subadult C. leucas remained in estuarine habitats. d 15 N values across shark vertebrae showed an ontogenetic shift in diet with total length (TL), confirmed by stomach contents. LA-ICPMS data reflected the ontogenetic movements of C. leucas from natal habitats. Differences among adults were gender related. Shifts in habitat use by subadults were correlated with a sigmoidal d 13 C relationship with TL. C. leucas have a multipartite, stage-specific dependency in their transition between habitats along the freshwaterestuarine-marine continuum, making them particularly susceptible to the habitat alteration that is occurring globally.
Australia A B S T R A C T Many commercially important fish species use coastal marine environment... more Australia A B S T R A C T Many commercially important fish species use coastal marine environments such as mangroves, tidal flats and seagrass beds as nurseries or breeding grounds. The ecological importance of spatially connected habitats to conservation is well established for terrestrial environments. However, few studies have applied spatial metrics, including measures of structural connectivity to marine environments. We examined the relationship between catch-per-unit-effort for commercially caught species and the spatial patterning of mapped benthic habitat types along the coast of Queensland, Australia in their dominant fisheries (trawl, line, net or pot fisheries). We quantified the composition and spatial configuration of seascapes and calculated coastline length, number of estuaries, river length and geographical latitude using 12 metrics within ninety 30-nautical-mile grid cells, which supported inshore fish catch data from 21 species groups. Multiple regression analysis and non-metric multidimensional scaling plots indicated that ecological linkages may exist between geomorphic coastal features and nearshore fisheries production for a number of species groups. Connectivity indices for mangroves, salt marsh and channels explained the largest proportion (30-70%), suggesting the importance of connected tidal wetlands for fisheries.
Analytical and Bioanalytical Chemistry, Jan 31, 2009
Investigation into persistent organic pollutants (POPs) in sea turtles is an important area of co... more Investigation into persistent organic pollutants (POPs) in sea turtles is an important area of conservation research due to the harmful effects of these chemicals. However, the analysis of POPs in the green sea turtle (Chelonia mydas) has been limited by methods with relatively high limits of detection and high costs associated with multiple sample injections into complex arrangements of analytical equipment. The present study aimed to develop a method that could detect a large number of POPs in the blood, eggs and tissue of C. mydas at trace concentrations. A gas chromatography with tandem mass spectrometry (GC-MS/MS) method was developed that could report 125 POP compounds to a limit of detection of <35 pg g −1 using a single sample injection. The recoveries of internal standards ranged from 30% to 96%, and the standard reference materials were reported to within 70% of the certified values. The coefficient of variation of ten replicates of pooled egg sample was <20% for all compounds, indicating low within-run variation. This GC-MS/MS method is an improvement of previous methods for analysing POPs in C. mydas in that more compounds can be reported at lower concentrations and the accuracy and precision of the method are sound. This is particularly important for C. mydas as they occupy a low trophic level and have lower concentrations of POPs. This method is also simple to set up, and there are minimal differences in sample preparation for the different tissue types.
Hammerhead sharks have experienced a drastic global reduction in abundance, yet limited data exis... more Hammerhead sharks have experienced a drastic global reduction in abundance, yet limited data exist on their general biology and population structure. We use generalised linear models (GLMs) to analyse historical mesh net and drumline catches (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) of Sphyrna lewini from the Queensland Shark Control Program (QSCP), which covers 10 locations on the north-east coast of Australia. Results show a significant decline in S. lewini female total length over the study period and a significant increase in annual CPUE on the Gold Coast. Sexual segregation was found in Cairns, where S. lewini males were most abundant. A positive linear relationship was found between maternal total length and litter size. Birthsize embryos were found in most months. However, normal birth size (0.50 m) embryos were found in pregnant females most often during spring and summer. Mesh nets were more selective for smaller S. lewini than drumlines. It is recognised that species selectivity of other, more potentially dangerous shark species varies between gear types, but replacement of mesh nets with drumlines would reduce the catch of smaller individuals of S. lewini and assist in their conservation.
Nitrogen stable isotope values (␦ 15 N) have commonly been used as a qualitative indicator of cat... more Nitrogen stable isotope values (␦ 15 N) have commonly been used as a qualitative indicator of catchment urbanization in estuaries, but no quantitative relationship has to date been established between ␦ 15 N and degree of urbanization. We sampled five species of common estuarine fish (Mugil cephalus, Acan-thopagrus australis, Sillago ciliata, Gerres subfasciatus and Herklotsichthys castelnaui) of different trophic levels from six estuaries in Southeast Queensland, Australia, to test if a quantitative relationship exists between fish ␦ 15 N and urbanization in the catchment. Degree of urbanization (urban %) in the catchment adjacent to the tidal estuary was measured using polygons constructed in Google Earth images, and verified using data from the detailed Queensland Land Use Mapping Project (QLUMP). Significant linear relationships exist between fish ␦ 15 N and urban % in most cases irrespective of the section of the estuary (upper, middle and lower) where the fish were caught, wit...
Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pe... more Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), have a wide range of toxic effects on humans and wildlife, and have been reported in a number of endangered sea turtle populations. The present study screened for POPs in a green sea turtle Chelonia mydas population in Peninsular Malaysia and investigated the maternal transfer and effects of POPs on embryonic development. At the Ma'Daerah Turtle Sanctuary, blood, eggs and hatchling blood were collected from 11 nesting female C. mydas. Samples were analysed for 83 PCBs, 23 OCPs and 19 PBDEs using gas chromatography with tandem mass spectrometry. The chemical profiles of eggs from individual turtles were significantly different, indicating variable contaminant uptake during foraging. There was evidence of maternal transfer of POPs to eggs and hatchlings, with significant correlations in sum of PCBs (ΣPCB), sum of PBDEs (ΣPBDE), γ-hexachlorocyclohexane (γ-HCH), trans-chlordane and mirex concentrations between maternal blood and eggs (p < 0.05, R 2 < 0.71), between eggs and hatchling blood (p < 0.05, R 2 < 0.83), and between maternal and hatchling blood (p < 0.05, R 2 < 0.61). In addition, there was congener-specific transfer of PCBs with less lipophilic congeners (e.g. PCB 99) more readily transferred to hatchlings than the more lipophilic congeners (e.g. PCBs 180 + 193). There was also a significant correlation between increasing egg POP concentration and decreasing hatchling mass:length ratio. POPs may therefore have subtle effects on the development of C. mydas eggs, which may compromise offshore dispersal and predator avoidance.
The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in t... more The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in the Indo-West-Pacific. It has a complex life cycle with a dispersing larvae phase, and benthic juveniles and adults. The former are stenohaline depending on high-salinity conditions to survive, whereas the latter are physiologically well adapted to changing temperatures and salinities, conditions that typically occur in mangrove habitats. Movement and habitat use of large juveniles and adults are well studied, and these life stages are known to utilize and move between various habitats within the mangrove ecosystem: intertidal flats as well as subtidal channels and flats. Females undertake long movements from brackish inshore waters to waters with oceanic conditions for spawning. Sensory abilities-of early stages and adult stageshave hardly been studied, and little is known about larval and early benthic stages in the wild. Summarizing, the literature revealed substantial gaps in the understanding of the spatiotemporal dynamics of the different life stages and of the clues that trigger recruitment, movement, and other behavior. This is the first comprehensive review on the life history, movement patterns, habitat use, and systemic role of S. serrata with emphasis on the respective life stages and geographic differences. We emphasize the need for further research into these processes as a basis for the sustainable management and conservation of this species.
Context. Many green sea turtle (Chelonia mydas) populations are declining worldwide owing to thei... more Context. Many green sea turtle (Chelonia mydas) populations are declining worldwide owing to their susceptibility to human impacts in the marine environment. Identifying the habitats used throughout different lifecycle stages is therefore important for managing the interactions between turtles and humans.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2015
The sesarmid crab Parasesarma erythodactyla consumes large amounts of mangrove leaf litter but it... more The sesarmid crab Parasesarma erythodactyla consumes large amounts of mangrove leaf litter but its biochemical capacity for cellulose digestion is poorly known. We demonstrate the presence of endo-β-1,4-glucanase, β-glucosidase and total cellulase activities in the digestive juice of this crab. The highest total cellulase activity was observed at mildly acidic pH (5 to 6) and temperature between 30 and 50°C. A 1752 bp cDNA containing an open reading frame of 1386 bp encoding a putative endo-β-1,4-glucanase (EG) of 461 amino acids was identified in the crab's hepatopancreas using polymerase chain reaction (PCR), cloning and sequencing techniques. P. erythodactyla endo-β-1,4-glucanase (PeEG) contains a glycosyl hydrolase family 9 (GHF9) catalytic domain with all catalytically important residues conserved, and shows high sequence identity to GHF9 EGs reported from other arthropods. The endogenous origin of PeEG was confirmed by PCR amplification of a~1.5 kb DNA fragment, containing a phase 1 intron flanked by two exon sequences identical to the cDNA, from genomic DNA isolated from the crab's muscle tissue. PeEG encoding cDNA is the first endogenous EG sequence reported from the brachyuran crabs. Using degenerate primers, we also isolated 204 bp cDNA fragments with sequences affiliated to EG from the hepatopancreas of eight other mangrove crabs of the Sesarmidae (Neosarmatium trispinosum and Sesarmoides borneensis), Macrophthalmidae (Ilyograpsus daviei, Australoplax tridentata, and Macrophthalmus setosus), Varunidae (Pseudohelice subquadrata), Heloeciidae (Heloecius cordiformis), and Ocypodidae (Uca perplexa) families, suggesting that endogenous cellulase production may be a common characteristic among the detritivorous mangrove crabs.
1. Structural complexity, that is, spatial patterns of structural 'units of interest', is one of ... more 1. Structural complexity, that is, spatial patterns of structural 'units of interest', is one of the most fundamental drivers in habitat use of animals and other functions of habitats. Assessment of habitat structural complexity (e.g. mangrove root complexity) and its ecological implications (e.g. mangroves as nursery sites) has, however, been hampered by the lack of satisfactory methods for realistically measuring and analysing field habitat structure. 2. We demonstrate a simple low-cost approach comprising an RGB_D scanning sensor (Kinect), free and readily accessible software (Meshlab, Matlab (or Octave), Qubicle Constructor and Voxeliser) and fractal dimension to measure mangrove root structure and complexity at spatial scales relevant to juvenile fish use of the habitat. The cube-counting method was used for three-dimensional characterisation of fractal dimensions of space around aerial roots of mangroves from a 'fish point of view'. Space-fish relationship under different ecological situations was assessed by simulating a falling tide and using different rectangular prisms to represent varying fish allometries utilizing the space. 3. Fractal dimension (FD) of space around roots decreased with decreasing height of the 'object' mimicking a falling tide. The same root system may therefore look more complex to aquatic animals as the water level decreases. We also assessed the variation in FD responding to manipulation of the density and arrangement of objects (pneumatophores). Difference in FD was generally small, due attention to replication is necessary for comparisons of habitat structural complexity using this metric. 4. This simple low-cost approach will enable field measurements of habitat structure at spatial scales relevant to its influence on habitat use and animal behaviour, as well as allowing realistic replication of field structure for laboratory-based experiments.
In whole-sediment toxicity tests employing metal-spiked sediment, pH is a crucial determinant of ... more In whole-sediment toxicity tests employing metal-spiked sediment, pH is a crucial determinant of sediment geochemistry, sediment-porewater metal partitioning and metal bioavailability to benthic organisms. Small pH changes in metal-spiked sediment may therefore have important implications for toxicity to organisms. The present study evaluated the effect of small-scale pH changes (pH 6.6, 7.2, 7.6) in Cu-spiked sediment on metal bioavailability and subsequent organism response. Variation of pH produced distinct changes in sediment geochemistry. Increasing pH from 6.6 to 7.6 resulted in lower redox potential, greater acid volatile sulfide (AVS) formation, and lower partitioning of Cu, Fe and
Background: Despite accelerated global population declines due to targeted and illegal fishing pr... more Background: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN 'Near-threatened' species -one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species.
Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green tur... more Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green turtle (Chelonia mydas) populations worldwide. However, due to ethical considerations, these studies have generally been on tissues from deceased and stranded animals. The purpose of this study was to investigate the use of blood samples to estimate the tissue contamination of live C. mydas populations. This study analysed 125 POP compounds and eight heavy metals in the blood, liver, kidney and muscle of 16 C. mydas from the Sea World Sea Turtle Rehabilitation Program, Gold Coast, Australia. Strong correlations were observed between blood and tissue concentrations for a number of POPs and metals. Furthermore, these correlations were observed over large ranges of turtle size, sex and condition. These results indicate that blood samples are a reliable non-lethal method for predicting chemical contamination in C. mydas.
Past studies on the size and structure of the chelipeds of predatory crabs have focused mainly on... more Past studies on the size and structure of the chelipeds of predatory crabs have focused mainly on their use in foraging. This study of the morphometrics of the chelipeds of 2 predatory portunid crabs, Carcinus maenas L. and Liocarcinus holsatus (Fabricius) and the use of these structures in feeding, reproduction and agonistic interactions, provides further support to the view that the evolution of crab chelae is not driven by feeding requirements alone. Although individuals with larger chelipeds can feed on a wider range of prey species and sizes, the proportion of hard-bodled prey in the natural diet of C. maenas was small. Bigger chelae, however, confer selective advantages by increasing success in mate competition and intraspecific agonistic interactions. Field collections of mating pairs of C. maenas indicated that > 90 % of mating males had chelae that were above the average size for the male population as a whole. Agonistic encounter experiments, in which crab models (constructed from empty moults) with chelae that were either larger than or smaller than the mean population values were presented to conspecifics suggested that cheliped size and meral spread was probably more important than overall body size in determining the response pattern of the subjects. Maintenance costs for chelipeds in L. holsatus estimated by respirometry were not significantly different from other body tissues as oxygen uptake rate could be predicted solely from dry tissue weight. Moreover, the rate of oxygen uptake was independent of the proportion of the total body weight that could be attributed to the chelipeds.
Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pe... more Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), have a wide range of toxic effects on humans and wildlife, and have been reported in a number of endangered sea turtle populations. The present study screened for POPs in a green sea turtle Chelonia mydas population in Peninsular Malaysia and investigated the maternal transfer and effects of POPs on embryonic development. At the Ma'Daerah Turtle Sanctuary, blood, eggs and hatchling blood were collected from 11 nesting female C. mydas. Samples were analysed for 83 PCBs, 23 OCPs and 19 PBDEs using gas chromatography with tandem mass spectrometry. The chemical profiles of eggs from individual turtles were significantly different, indicating variable contaminant uptake during foraging. There was evidence of maternal transfer of POPs to eggs and hatchlings, with significant correlations in sum of PCBs (ΣPCB), sum of PBDEs (ΣPBDE), γ-hexachlorocyclohexane (γ-HCH), trans-chlordane and mirex concentrations between maternal blood and eggs (p < 0.05, R 2 < 0.71), between eggs and hatchling blood (p < 0.05, R 2 < 0.83), and between maternal and hatchling blood (p < 0.05, R 2 < 0.61). In addition, there was congener-specific transfer of PCBs with less lipophilic congeners (e.g. PCB 99) more readily transferred to hatchlings than the more lipophilic congeners (e.g. PCBs 180 + 193). There was also a significant correlation between increasing egg POP concentration and decreasing hatchling mass:length ratio. POPs may therefore have subtle effects on the development of C. mydas eggs, which may compromise offshore dispersal and predator avoidance.
Fatty acid compositions of the leaves of six species of mangroves were studied to ascertain their... more Fatty acid compositions of the leaves of six species of mangroves were studied to ascertain their use as biomarkers for determining the fate of mangrove organic matter in the habitat and as taxonomic tool. Mangrove leaves were collected from three locations in the western PaciWc Ocean: Moreton Bay (MB) (Australia), Hong Kong (China) and Okinawa (Japan). In MB, samples were collected from two sites separated by 15 km: Logan River Estuary (LRE) and Jabiru Island. In addition, along the LRE, leaves were collected from Wve stations at »2-3 km apart. Results show that the analysis of the entire fatty acid proWles of the mangrove leaves is a promising taxonomic tool as the proWles of most species were suYciently diVerent to be separated in an non-metric multidimensional scaling plot. In addition, geographically separated populations of the same species could also be identiWed by their fatty acid proWles. In most cases, two non-ubiquitous groups of fatty acids dominated in the mangrove leaves: the polyunsaturated 18:2 6 and 18:3 3 and the long chain fatty acids (¸24:0). With respect to the relative contributions of these fatty acids, three groups of species were identiWed, in which one or both groups of fatty acids may potentially be used as markers of the mangrove organic matter in the estuarine environment.
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