Lizard Island Research Articles

Two new species of threadlike blood flukes (Aporocotylidae), with a molecular revision of the genera Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006

Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006 are sister genera of threadlike blood flukes (Trematoda: Aporocotylidae) infecting teleost fishes of the tropical Indo-west Pacific. Here, we report new collections of these genera from Australia, Indonesia, and Japan. A new species of Ankistromeces, Ankistromeces kawamurai n. sp., is described from Siganus spinus (Linnaeus) off Okinawa, Japan, and a new species of Phthinomita, Phthinomita abdita n. sp., from Choerodon cephalotes (Castelnau), in Moreton Bay, Australia; the new species are morphologically cryptic within their respective genera and are delineated by molecular and ecological data. Ankistromeces olsoni Nolan & Cribb, 2006 is reported from Siganus fuscescens (Houttuyn) off Heron Island (southern Great Barrier Reef), Lizard Island (northern Great Barrier Reef), and Okinawa and Wakayama Prefectures, Japan and from Siganus spinus (Linnaeus) from off Bali, Indonesia. Ankistromeces mariae Nolan & Cribb, 2004 is re-reported from the type-host, Meuschenia freycineti (Quoy & Gaimard), from a new location, Gypsy Bay, Tasmania. Phthinomita poulini Nolan & Cribb, 2006 is re-reported from its type-locality, Lizard Island, from a range of mullids, including five new host species, and its range is extended to include Moreton Bay. Phthinomita symplocos Nolan & Cribb, 2006 is reported from Bali and P. hallae Nolan & Cribb, 2006, P. jonesi Nolan & Cribb, 2006, P. littlewoodi Nolan & Cribb, 2006, and P. munozae Nolan & Cribb, 2006 are each re-reported from their type-host and type-localities. New cox1 mtDNA data were generated for all known species of these two genera from new and archival material. Analyses of these data enabled an evaluation of all known Phthinomita species; P. robertsthomsoni Nolan & Cribb, 2006 is synonymised with P. adlardi Nolan & Cribb, 2006, and P. brooksi Nolan & Cribb, 2006 is synonymised with P. sasali Nolan & Cribb, 2006. We highlight the failure of ITS2 data to delineate closely related aporocotylid species. In contrast, cox1 sequence data are proving reliable and effective in this context and we recommend their incorporation in future studies of blood fluke taxonomy.

Spatio-temporal persistence of scleractinian coral species at Lizard Island, Great Barrier Reef

Spatio-temporal persistence of scleractinian coral species at Lizard Island, Great Barrier Reef

SAR-BASED COASTLINE DETECTION AND MONITORING

Abstract. The coastal environment is among the most fragile regions on our planet. Its efficient monitoring is crucial to properly manage human and natural resources located in this environment where a large portion of our population lives. The objective of this contribution is to design and develop a new set of methods suitable for detecting and tracking the coastline. Synthetic aperture radar (SAR) technology is chosen because of the characteristic response from water and the acquisition consistency allowed by constant illumination, day-and-night, and all-weather functioning. The proposed iterative detection method is based on superpixel segmentation. The resulting superpixels are filtered and then partitioned in land and water classes based on their median backscattering with Otsu’s algorithm. The rationale is that the segmentation can follow the coastline before the filtering can degrade the spatial resolution. A quantitative assessment of the results measures the distance to a manually-detected shoreline for the Lizard Island case study; the average distance is 12.63 m, with 80% of the sampled points within 20 m. The innovative coastline monitoring process exploits the consistency of SAR by analyzing a long time series. After a season-wise grouping, the land-water index is introduced to erase the time oscillation of water backscattering caused by different sea states. The proposed index is modeled in time on a pixel basis. A visualization technique that exploits the HSV codification of the color space highlights where and when changes happened. A case study for this technique is carried out over the Reentrancias Maranhenses natural area. A quality assessment shows good accordance with optical data that depicts the region’s dynamic.

Long-term demographics of a coral-reef fish: growth, survival and abundance at several spatial scales

In marine organisms, pelagic larval dispersal often results in genetic panmixis among widely separated populations; however, local conditions may produce populations of marine organisms that differ in key life history traits. Here, we assess spatial differences in growth, body condition, survivorship and movement over a decade for lemon damselfish Pomacentrus moluccensis. Newly recruited fish were tagged on the southern (One Tree Island, 23°S), and northern Great Barrier Reef (Lizard Island, 15°S), 1200 km apart, and monitored for over a decade to provide direct data on growth and survivorship. New recruit physiological condition (lipid content) had a weak positive influence on early survival, but not on long-term persistence or growth, and the larval supply signal was lost after 2 years, suggesting post-settlement processes were key in long-term population persistence. Fish exhibited extreme site fidelity, with older/larger fish moving most (all less than 7 m). At Lizard Island, under 5% of individuals remained after 3 years, none after 4 years, while at One Tree Island 5% of individuals survived over 5 years, with 1% remaining after a decade, suggesting Lizard Island populations may require more frequent replenishment to persist. Among-site (within location) variation in mortality was high, and not related to density, suggesting local conditions such as wave exposure and predators were important. Surprisingly, mean growth at the two locations, which differ by around 2 °C on average in sea temperature, was practically identical, levelling off after 3 years, but with high variation among nearby sites within each location, which would affect size-based fecundity and time of first reproduction at these smaller spatial scales. Neither early post-settlement growth nor mortality were density-dependent, and early growth was not related to overall longevity. These small reef fishes are highly sedentary and some demographic parameters, but not others, differ at a range of scales, with post-settlement populations likely driven largely by mortality patterns at the larger spatial scale. Latitudinal and smaller-spatial scale differences in performance (growth, survival) of this species, leading to offsets in expected time to maturity an fecundity, are contrasted by evidence of stability of adult populations over two decades at One Tree Island, which suggests that resilience to environmental change/climate change and other externalities differ considerably across this species’ distribution.

Detection of Coral Reef Bleaching Based on Sentinel-2 Multi-Temporal Imagery: Simulation and Case Study

Sentinel-2 mission has been shown to have promising applications in coral reef remote sensing because of its superior properties. It has a 5-day revisit time, spatial resolution of 10 m, free data, etc. In this study, Sentinel-2 imagery was investigated for bleaching detection through simulations and a case study over the Lizard Island, Australia. The spectral and image simulations based on the semianalytical (SA) model and the sensor spectral response function, respectively, confirmed that coral bleaching cannot be detected only using one image, and the change analysis was proposed for detection because there will be a featured change signal for bleached corals. Band 2 of Sentinel-2 is superior to its other bands for the overall consideration of signal attenuation and spatial resolution. However, the detection capability of Sentinel-2 is still limited by the water depth. With rapid signal attenuation due to the water absorption effect, the applicable water depth for bleaching detection was recommended to be less than 10 m. The change analysis was conducted using two methods: one radiometric normalization with pseudo invariant features (PIFs) and the other with multi-temporal depth invariant indices (DII). The former performed better than the latter in terms of classification. The bleached corals maps obtained using the PIFs and DII approaches had an overall accuracy of 88.9 and 57.1%, respectively. Compared with the change analysis based on two dated images, the use of a third image that recorded the spectral signals of recovered corals or corals overgrown by algae after bleaching significantly improved the detection accuracy. All the preliminary results of this article will aid in the future studies on coral bleaching detection based on remote sensing.

The role of corals on the abundance of a fish ectoparasite in the Great Barrier Reef

Gnathiid isopods, common fish ectoparasites, can affect fish physiology, behaviour and survival. Gnathiid juveniles emerge from the benthos to feed on fish blood. In the Caribbean, gnathiids are positively associated with dead coral and negatively associated with live coral, due to coral predation on gnathiids. However, such interactions were unstudied in the Great Barrier Reef (GBR). Due to recent extreme weather events (two cyclones and one mass warm-water coral bleaching event, 2014–2016), it is now urgent to understand the role of corals on the abundance of these ectoparasites. Here, to understand parasite–coral dynamics at the micro-habitat level, we examined substrate associations of gnathiid isopods on Lizard Island (GBR) using demersal plankton emergence traps. Additionally, we determined whether two abundant hard coral species, Goniopora lobata and Pocillopora damicornis, predate on gnathiids in a laboratory experiment using containers with gnathiids and fragments from each coral species or dead coral as controls. The abundance of gnathiids over natural substrates was higher for dead compared to live hard coral and sand, but not live soft coral. Moreover, we found that free-swimming gnathiids decreased in containers with live coral compared to dead coral controls. This was attributed to predation as we also directly observed a coral ingesting a gnathiid. Our results suggest that dead coral is a suitable microhabitat for gnathiids, but that live coral is not since live corals can predate on gnathiids. We propose that following extreme events, such as cyclones and heat waves, gnathiids might benefit from more dead coral substrate and a decrease in predation by the reduction in coral cover on the reef. We advocate that an increase in the frequency of extreme events may have cascading effects for the fish population through changes in the population of benthos-dependent ectoparasites.

Ecomorphological divergence and trophic resource partitioning in 15 syntopic Indo-Pacific parrotfishes (Labridae: Scarini)

AbstractAdaptive diversification is a product of both phylogenetic constraint and ecological opportunity. The species-rich parrotfish genera Scarus and Chlorurus display considerable variation in trophic cranial morphology, but these parrotfishes are often described as generalist herbivores. Recent work has suggested that parrotfish partition trophic resources at very fine spatial scales, raising the question of whether interspecific differences in cranial morphology reflect trophic partitioning. We tested this hypothesis by comparing targeted feeding substrata with a previously published dataset of nine cranial morphological traits. We sampled feeding substrata of 15 parrotfish species at Lizard Island, Great Barrier Reef, Australia, by following individuals until focused biting was observed, then extracting a bite core 22 mm in diameter. Three indices were parameterized for each bite core: substratum taphonomy, maximum turf height and cover of crustose coralline algae. Parrotfish species were spread along a single axis of variation in feeding substrata: successional status of the substratum taphonomy and epilithic and endolithic biota. This axis of trophic variation was significantly correlated with cranial morphology, indicating that morphological disparity within this clade is associated with interspecific partitioning of feeding substrata. Phylogenetic signal and phylomorphospace analyses revealed that the evolution of this clade involved a hitherto-unrecognized level of trophic diversification.

Autonomous in situ calibration of ion‐sensitive field effect transistor pH sensors

AbstractIon‐sensitive field effect transistor‐based pH sensors have been shown to perform well in high frequency and long‐term ocean sampling regimes. The Honeywell Durafet is widely used due to its stability, fast response, and characterization over a large range of oceanic conditions. However, potentiometric pH monitoring is inherently complicated by the fact that the sensors require careful calibration. Offsets in calibration coefficients have been observed when comparing laboratory to field‐based calibrations and prior work has led to the recommendation that an in situ calibration be performed based on comparison to discrete samples. Here, we describe our work toward a self‐calibration apparatus integrated into a SeapHOx pH, dissolved oxygen, and CTD sensor package. This Self‐Calibrating SeapHOx is capable of autonomously recording calibration values from a high quality, traceable, primary reference standard: equimolar tris buffer. The Self‐Calibrating SeapHOx's functionality was demonstrated in a 6‐d test in a seawater tank at Scripps Institution of Oceanography (La Jolla, California, U.S.A.) and was successfully deployed for 2 weeks on a shallow, coral reef flat (Lizard Island, Australia). During the latter deployment, the tris‐based self‐calibration using 15 on‐board samples exhibited superior reproducibility to the standard spectrophotometric pH‐based calibration using > 100 discrete samples. Standard deviations of calibration pH using tris ranged from 0.002 to 0.005 whereas they ranged from 0.006 to 0.009 for the standard spectrophotometric pH‐based method; the two independent calibration methods resulted in a mean pH difference of 0.008. We anticipate that the Self‐Calibrating SeapHOx will be capable of autonomously providing climate quality pH data, directly linked to a primary seawater pH standard, and with improvements over standard calibration techniques.

Isoprene fluxes from warm temperate and tropical seagrass communities

Isoprene is an important biogenic volatile organic compound (BVOC), with a contribution to annual greenhouse gas emissions similar to that of methane in terms of carbon equivalent. Isoprene is mostly produced by terrestrial vegetation, although marine ecosystems also play an important role in isoprene production. Here, we report isoprene fluxes from warm temperate seagrass communities dominated by specific seagrass species (Posidonia australis, Zostera muelleri and Halophila ovalis) in Wallis Lake, NSW, Australia, and from tropical seagrass communities (H. ovalis/Halodule uninervis mixed patches) on Lizard Island, QLD, Australia. P. australis and Z. muelleri were net isoprene sinks (-0.6 ± 0.1 and -3.4 ± 2.0 nmol m-2 h-1, respectively), whereas H. ovalis (2.4 ± 0.2 nmol m-2 h-1) and mixed patches of H. ovalis/H. uninervis (13.2 ± 3.2 nmol m-2 h-1) were a net source of isoprene, indicating that seagrass communities can be both a source of and a sink for isoprene on a local scale depending on species. Overall, isoprene effluxes were more than 5 times higher on Lizard Island than in Wallis Lake, likely due to higher temperatures and prolonged sunlight on Lizard Island during the time of measurement. Wallis Lake and Lizard Island seagrass communities emit isoprene to the water column at an average rate of -0.3 and 8 mg m-2 yr-1, respectively. Seagrass communities are a benthic source of isoprene in coastal waters, but only make a small contribution (2.3 Gg C yr-1) to the global marine isoprene flux (11.6 Tg C yr-1).

A new order of fishes as hosts of blood flukes (Aporocotylidae); description of a new genus and three new species infecting squirrelfishes (Holocentriformes, Holocentridae) on the Great Barrier Reef.

A new genus and three new species of blood flukes (Aporocotylidae) are described from squirrelfishes (Holocentridae) from the Great Barrier Reef. Holocentricola rufus n. gen., n. sp. is described from Sargocentron rubrum (Forsskål), from off Heron Island, southern Great Barrier Reef, and Lizard Island, northern Great Barrier Reef, Australia. Holocentricola exilis n. sp. and Holocentricola coronatus n. sp. are described from off Lizard Island, H. exilis from Neoniphon sammara (Forsskål) and H. coronatus from Sargocentron diadema (Lacepède). Species of the new genus are distinct from those of all other aporocotylid genera in having a retort-shaped cirrus-sac with a distinct thickening at a marginal male genital pore. The new genus is further distinct in the combination of a lanceolate body, X-shaped caeca, posterior caeca that are longer than anterior caeca, a single, post-caecal testis that is not deeply lobed, a post-caecal, post-testis ovary that is not distinctly bi-lobed, and a post-ovarian uterus. The three new species can be morphologically delineated based on the size and row structure of the marginal spines, as well by total length, oesophagus and caecal lengths, and the position of the male genital pore, testes and ovary relative to the posterior extremity. The three species of Holocentricola are genetically distinct from each other based on cox1 mtDNA and ITS2 rDNA data, and in phylogenetic analyses of 28S rDNA form a well-supported clade sister to species of Neoparacardicola Yamaguti, 1970. This is the first report of aporocotylids from fishes of the family Holocentridae and the order Holocentriformes.

Nocturnal reef residents have deep-sea-like eyes

Swirling with colour, coral reefs teem with vivid life during daylight. But at night, a different crew emerges from the nooks and crannies. ‘The visual systems of teleost fish usually match their habitats and lifestyles’, says Fanny de Busserolles from The University of Queensland (UQ), Australia, explaining that there has been a lot of interest in the vision of the gaudy creatures that populate reefs by day. However, less was known about the vision of their nocturnal cohabitants. ‘I am particularly interested in visual adaptations and capabilities in dim light’, says de Busserolles, who is intrigued by the vision of deep-sea fish. So, when she arrived in subtropical Brisbane to work with Justin Marshall at UQ, the chance to investigate some of the nocturnal creatures residing on the Great Barrier Reef was too good to pass up.‘Holocentrids [squirrelfish and soldierfish] were the ideal family for our study due to their connection to the deep-sea environment’, says de Busserolles, explaining that the fish are linked to her love of the depths; ‘the entire family is thought to have originated in deeper water before most of its representatives migrated up to the reef’, she says. Fishing in the sea around Lizard Island, Australia, with UQ colleagues Fabio Cortesi, Sara Stieb, Martin Luehrmann and Marshall, de Busserolles collected four species of soldierfish and five different squirrelfish. ‘They were pretty hard to catch during the day because they are very shy and tend to hide in holes, caves and crevices’, de Busserolles recalls.Looking at the overall structure of the eyes back in Brisbane, de Busserolles could see that they were large, to collect as much light as possible in the dim conditions. And, when Cortesi extracted the RNA from each retina to find out which light-sensitive genes the fish were expressing, he found that all of the fish expressed one rod opsin – which they produced in high levels in their light-sensitive rod cells. In addition, the fish expressed some colour-sensitive cone opsin genes, but at much lower levels than the rod opsin, with the soldierfish expressing two cone opsins while the squirrelfish expressed three cone opsins. Luehrmann also simulated which shades the colour-sensitive cone opsins detect and it turned out that they pick up shades of green and blue. In addition, Sara Stieb revealed two types of cone in the fishes’ retinas: cones expressing the blue opsin, with a second type expressing one or two green opsin genes. ‘These findings indicate that holocentrids may be able to see colours during the day’, says de Busserolles.However, when she and Lily Fogg (also from UQ), painstakingly investigated the distribution of photoreceptor cells in the fishes’ retinas, it was apparent that their eyes are also extremely well prepared for dim nocturnal conditions. Instead of carrying a single layer of photoreceptors at the back of the eye, the fish's retinas comprised stacks of rod cells layered one on top of another, with up to 17 rod cell layers in the eyes of crimson soldierfish (Myripristis murdjan). Explaining that these ‘multibank’ retinas are mostly found in deep-sea species, de Busserolles says, ‘We do not know what the function of this adaptation is, but possible hypotheses are that they may enhance the sensitivity of the eye and/or they may provide some kind of colour vision in dim light conditions’.So, soldierfish and squirrelfish are well prepared for their nocturnal life on the Great Barrier Reef and de Busserolles and her colleagues are keen to find out just how good the fish's colour vision is, especially in the dimmest conditions.

Beetle Diversity Across Micro-habitats on Lizard Island Group (Great Barrier Reef, Australia).

The beetles (Coleoptera) of Lizard Island group, a complex of small granitic islands on the Great Barrier Reef, have never been systematically assessed. In April 2019, we conducted the first survey of the island group across different micro-habitats. We specifically aimed to determine which beetle families are the most diverse, and how beetle diversity varies across the island group. We sampled several sites on seven large collection areas using a variety of methods: pitfall traps, beating sheet, sifting leaf litter, and active night and day collection. Our sampling yielded 108 beetle morphospecies representing at least 21 families. The most diverse families on Lizard Island group were Curculionidae, Carabidae, Scarabaeidae, Tenebrionidae, and Cerambycidae, in general accordance with global patterns in Coleoptera diversity. The families Chrysomelidae, Staphylinidae, and Buprestidae were found to be proportionally less diverse on the island group than on mainland Australia, though Australia as a whole is of limited value as a reference. Beetle diversity varied across both large-scale collection areas and small-scale collection sites on Lizard Island group. As expected, greater habitat complexity and vegetation diversity corresponded with greater beetle diversity, though these patterns might be biased due to the temporal and spatial limits of our sampling. We hope this preliminary survey will facilitate further research on Lizard Island group, taking advantage of the research facilities on the island and the possibility of establishing long-term studies.

Changing use of Lizard Island over the past 4000 years and implications for understanding Indigenous offshore island use on the Great Barrier Reef

Archaeological records documenting the timing and use of northern Great Barrier Reef offshore islands by Aboriginal and Torres Strait Islander peoples throughout the Holocene are limited when compared to the central and southern extents of the region. Excavations on Lizard Island, located 33 km from Cape Flattery on the mainland, provide high resolution evidence for periodic, yet sustained offshore island use over the past 4000 years, with focused exploitation of diverse marine resources and manufacture of quartz artefacts. An increase in island use occurs from around 2250 years ago, at a time when a hiatus or reduction in offshore island occupation has been documented for other Great Barrier Reef islands, but concurrent with demographic expansion across Torres Strait to the north. Archaeological evidence from Lizard Island provides a previously undocumented occupation pattern associated with Great Barrier Reef late Holocene island use. We suggest this trajectory of Lizard Island occupation was underwritten by its place within the Coral Sea Cultural Interaction Sphere, which may highlight its significance both locally and regionally across this vast seascape.

Acoustic Characteristics of Small Research Vessels

Vessel noise is an acute and chronic stressor of a wide variety of marine fauna. Understanding, modelling and mitigating the impacts of this pollutant requires quantification of acoustic signatures for various vessel classes for input into propagation models and at present there is a paucity of such data for small vessels (<25 m). Our study provides this information for three small vessels (<6 m length and 30, 90 and 180 hp engines). The closest point of approach was recorded at various ranges across a flat, ≈10 m deep sandy lagoon, for multiple passes at multiple speeds (≈5, 10, 20, 30 km h−1) by each vessel at Lizard Island, Great Barrier Reef, Australia. Radiated noise levels (RNLs) and environment-affected source levels (ASLs) determined by linear regression were estimated for each vessel and speed. From the slowest to fastest speeds, median RNLs ranged between 153.4 and 166.1 dB re 1 µPa m, whereas ASLs ranged from 146.7 to 160.0 dB re 1 µPa m. One-third octave band-level RNLs are provided for each vessel–speed scenario, together with their interpolated received levels with range. Our study provides data on source spectra of small vessels to assist in understanding and modelling of acoustic exposure experienced by marine fauna.

Helmutneris vadum, a new species of Lumbrineridae (Annelida) from Lizard Island, Great Barrier Reef, Australia.

A new species of Lumbrineridae, Helmutneris vadum n. sp., is described from shallow waters near Lizard Island, Great Barrier Reef, Queensland, Australia. The new species differs from two other known species of Helmutneris by having bidentate maxillae III and no ventral limbate chaetae. Sequences of the fragments of COI and 16S rDNA for two specimens including the holotype are deposited in GenBank. A key for three species of Helmutneris known to date is provided.

Optimising cool-water injections to reduce thermal stress on coral reefs of the Great Barrier Reef.

Coral bleaching driven by ocean warming is one of the most visible ecological impacts of climate change and perhaps the greatest threat to the persistence of reefs in the coming decades. In the absence of returning atmospheric greenhouse gas concentrations to those compatible with ocean temperatures below the mass coral bleaching temperature thresholds, the most straightforward means to reduce thermal-stress induced bleaching is to cool water at the seabed. The feasibility of reducing the seabed temperature through cool-water injections is considered first by analysing the feasibility of doing so on 19 reefs with differing physical environments using a simple residence time metric in 200 m resolution hydrodynamic model configurations. We then concentrate on the reefs around Lizard Island, the most promising candidate of the 19 locations, and develop a 40 m hydrodynamic model to investigate the effect of the injection of cool water at differing volumetric rates. Injecting 27°C seawater at a rate of 5 m3 s−1 at 4 sites in early 2017 cooled 97 ha of the reef by 0.15°C or more. The power required to pump 5 m3 s−1 through a set of pipes over a distance of 3 km from a nearby channel is ∼466 kW. This power applied at 4 sites for 3 months achieves a 2 Degree Heating Weeks (DHWs) reduction on 97 ha of reef. A more precise energy costing will require further expert engineering design of the pumping equipment and energy sources. Even for the most physically favourable reefs, cool-water transported through pipes and injected at a reef site is energy expensive and cannot be scaled up to any meaningful fraction of the 3,100 reefs of the GBR. Should priority be given to reducing thermal stress on one or a few high value reefs, this paper provides a framework to identify the most promising sites.

Boring bivalve traces in modern reef and deeper-water macroid and rhodolith beds

Macroids and rhodoliths, made by encrusting acervulinid foraminifera and coralline algae, are widely recognized as bioengineers providing relatively stable microhabitats and increasing biodiversity for other species. Macroid and rhodolith beds occur in different depositional settings at various localities and bathymetries worldwide. Six case studies of macroid/rhodolith beds from 0 to 117 m water depth in the Pacific Ocean (northern Central Ryukyu Islands, French Polynesia), eastern Australia (Fraser Island, One Tree Reef, Lizard Island), and the Mediterranean Sea (southeastern Spain) show that nodules in the beds are perforated by small-sized boring bivalve traces (Gastrochaenolites). On average, boring bivalve shells (gastrochaenids and mytilids) are more slender and smaller than those living inside shallow-water rocky substrates. In the Pacific, Gastrochaena cuneiformis, Gastrochaena sp., Leiosolenus malaccanus, L. mucronatus, L. spp., and Lithophaga/Leiosolenus sp., for the first time identified below 20 m water depth, occur as juvenile forms along with rare small-sized adults. In deep-water macroids and rhodoliths the boring bivalves are larger than the shallower counterparts in which growth of juveniles is probably restrained by higher overturn rates of host nodules. In general, most boring bivalves are juveniles that grew faster than the acervulinid foraminiferal and coralline red algal hosts and rarely reached the adult stage. As a consequence of phenotypic plasticity, small-sized adults with slow growth rates coexist with juveniles. Below wave base macroids and rhodoliths had the highest amounts of bioerosion, mainly produced by sponges and polychaete worms. These modern observations provide bases for paleobiological inferences in fossil occurrences.

Carpentaria gen. nov., a new talitrid genus from tropical Australia (Amphipoda, Senticaudata, Talitroidea, Protorchestiidae).

The new talitrid genus Carpentaria gen. nov. is described from tropical Australia. It contains two marsh-hoppers: C. limicola (Haswell, 1880) (comb. nov.) from Lizard Island, Great Barrier Reef and C. tropicalis sp. nov. from Darwin, Northern Territory and Queensland.

Retroporomonorchis pansho n. g., n. sp., an unusual monorchiid trematode exploiting an atypical host.

The Monorchiidae Odhner, 1911 are well represented in tropical and subtropical marine fishes worldwide but rarely reported from the Lutjanidae, an important family of tropical fishes that prey mainly on demersal fishes, decapods and cephalopods. Here, we report the first monorchiid from a lutjanid in Australian waters, Retroporomonorchis pansho n. g., n. sp. in Lutjanus fulvus (Forster), off Lizard Island on the northern Great Barrier Reef. It is morphologically and phylogenetically distinct among known monorchiids, resolves within the Monorchiinae Odhner, 1911, and is characterised by a relatively large ventral sucker, a sinistral genital pore immediately posterior to the ventral sucker, unfilamented eggs, a single testis, and vitelline follicles restricted to the level of the gonads. We assessed all previous records of monorchiids from lutjanid fishes and found only one to be convincing, that of Infundiburictus overstreeti (Gupta & Gupta, 1990) Wee, Cutmore, Pérez-del-Olmo & Cribb, 2020 from Lutjanus monostigma (Cuvier) in the Bay of Bengal. Another, Monorcheides xishaensis Shen, 1985, from Lutjanus argentimaculatus (Forsskål) in the Paracel Islands, South China Sea, is here recognised as a cryptogonimid, and is synonymised with Siphoderina asiatica Gu & Shen, 1979. In the remaining reports, the identity of the host is either ambiguous or doubtful, or the identity of the worm is not supported with sufficient evidence.

Isoprene flux from permeable carbonate sediments on the Great Barrier Reef

Isoprene is the most abundant biogenic volatile organic compound (BVOC) on the planet, with annual emissions accounting for up to half of all BVOC emissions. Isoprene has been measured extensively in terrestrial habitats where it is highly abundant; however, there is limited knowledge on marine systems where it is found at lower concentrations. Here, we report for the first time isoprene fluxes from coral reef permeable carbonate sediments with a cover of microphytobenthos (MPB) from Heron and Lizard Islands, on the southern and northern ends of the Great Barrier Reef, respectively. Using advective and diffusive benthic chambers, we measured isoprene fluxes over full diel cycles on both islands. Net effluxes of isoprene from the sediment to the water column were observed at both Heron Island (mean: 10.0 ± 1.1 nmol m2 h−1) and Lizard Island (mean: 3.9 ± 0.9 nmol m2 h−1). Light isoprene fluxes were much higher on Heron Island than on Lizard Island and both islands had lower isoprene emissions in the dark. Higher isoprene fluxes during the day reflects the role of MPB photosynthesis in isoprene production. Lower isoprene fluxes at night is most likely due to isoprene consumption by microbial activity or less production in the absence of photosynthesis. The contribution of benthic isoprene emissions from coral reef carbonate sands worldwide (0.52 Gg C y−1) were estimated to represent less than 0.005% of the global marine atmospheric fluxes (11,600 Gg C y−1).