A sponge allelochemical induces ascidian settlement but inhibits metamorphosis

Secondary metabolites synthesised by sessile invertebrates appear to play a role in creating and maintaining space on hard substrata by repelling competitors. In this study, we investigated the responses of the larvae of the ascidian Herdmania curvata to haliclonacyclamine A (HA), the major component of a suite of cytotoxic alkaloids extracted from the sponge Haliclona sp. 628. Both Haliclona sp. 628 and Herdmania curvata inhabit the crest and slope of Heron Island Reef. High rates of settlement were induced in competent H. curvata larvae by a range of concentrations of HA, all lower than that naturally occurring in the sponge. HA did not induce precompetent larvae to settle. Although early metamorphosis of HA-induced larvae was normal, larvae exposed to all but the lowest concentration of HA were developmentally arrested after completion of tail resorption, at about 4 h after the initiation of metamorphosis. These postlarvae underwent extensive cellular necrosis within 24 h. We also demonstrate that the addition of a transcriptional inhibitor, actinomycin D, to larvae also causes inhibition of metamorphosis after tail resorption is completed. Analyses of incorporation of radiolabelled nucleotides to measure levels of transcription during normal development and after the addition of the transcriptional inhibitor indicate that there is a significant burst of transcriptional activity just after tail resorption is completed. Despite inhibiting metamorphosis at the same stage as actinomycin D, HA increases initial rates of RNA synthesis after induction of metamorphosis in a manner similar to that observed in normal postlarvae until the onset of cellular necrosis. We conclude that HA initially induces H. curvata larvae to settle and progress through early metamorphosis possibly by engaging the same pathway as other artificial and environmental cues but subsequently inhibits completion of metamorphosis, resulting in death of the postlarvae. Since HA does not affect overall transcription rates, it appears to disrupt another important developmental process during early metamorphosis.

Asymmetric cheating opportunities and partner control in a cleaner fish mutualism

How can cooperation persist if, for one partner, cheating is more profitable than cooperation in each round, while the other partner has no option to cheat? Our laboratory experiments suggest that such a situation exists between the cleaner fish Labroides dimidiatus and its nonpredatory client reef fish species, which actively seek cleaners to have their ectoparasites removed. Clients Ctenochaetus striatus regularly jolted in response to cleaner mouth contact, and these jolts were not linked to the removal of parasites. In addition, cleaners did not search for parasites but fed on mucus when exposed to anaesthetized clients, which could not control the cleaners' behaviour. Field data showed that clients often terminated an interaction immediately after a jolt. Client species with access to only one cleaning station, owing to their small territories or home ranges, terminated interactions mainly by chasing cleaners while clients with access to two or more cleaning stations mainly swam away. Thus, the chasing of cleaners appeared to be a form of punishment, imposing costs on the cleaner at the client's (momentary) expense. Chasing yields future benefits, as jolts were on average less frequent during interactions between cleaners and individuals that had terminated their previous interaction by aggressive chasing. 2002 The Association for the Study of Animal Behaviour.

Cleaner fish Labroides dimidiatus reduce 'temporary" parasitic corallanid isopods on the coral reef fish Hemigymnus melapterus

To determine if cleaners affect 'temporary' parasitic corallanid isopods (Argathona macronema) on fish, we used caged fish Hemigymnus meldpterus (Labridae) on 5 patch reefs on Lizard Island, Great Barrier Reef, and removed all cleaner fish Labroides dimidiatus (Labridae) from 3 of the reefs, In a short-term experiment, fish were sampled after 12 or 24 h, at dawn and sunset respectively, and in a long-term experiment they were sampled after 12 d at sunset. Isopod prevalence, abundance and size were measured. In the short-term experiment, on reefs without cleaners the prevalence of A. macronema was higher after 24 h than after 12 h while on reefs with cleaners, prevalence was low at all times, Although the abundance of A, macronema did not vary after 12 and 24 h, when combined over the 24 h, the effect of cleaners was significant with only 2 % of all the A. macronema found on reefs with cleaners. Cleaners had no effect on the size frequency distribution of A. macronema in the short-term experiment, most likely because fish had so few isopods on reef with cleaners. In the longer-term experiment, the effects of cleaners on isopod prevalence and abundance were less clear. Their effect on isopod size was, however, significant with smaller parasites on reefs without cleaners. The reduction of isopod prevalence and abundance by cleaner fish over a period of hours may explain why these A, macronema are rare on wild fish. Our findings support the idea that cleaning is beneficial to clients and has important implications for the control of parasites of fish farmed in cages,

Geographic variation in the behaviour of the cleaner fish Labroides dimidiatus (Labridae)

Geographical variation in the outcome of interspecific interactions has a range of proximate ecological causes. For instance, cleaning interactions between coral reef fishes can result in benefits for both the cleaner and its clients. However, because both parties can cheat and because the rewards of cheating may depend on the local abundance of ectoparasites on clients, the interaction might range from exploitative to mutualistic. In a comparative analysis of behavioural measures of the association between the cleaner fish Labroides dimidiatus and all its client species, we compared cleaning interactions between two sites on the Great Barrier Reef that differ with respect to mean ectoparasite abundance. At Heron Island, where client fish consistently harbour fewer ectoparasites, client species that tended to pose for cleaners were more likely to receive feeding bites by cleaners than client species that did not pose for cleaners. This was not the case at Lizard Island, where ectoparasites are significantly more abundant. Client fish generally spent more time posing for cleaners at Lizard Island than their conspecifics at Heron Island. However, fish at Heron Island were inspected longer on average by cleaners than conspecifics at Lizard Island, and they incurred more bites and swipes at their sides per unit time from cleaners. These and other differences between the two sites suggest that the local availability of ectoparasites as a food source for cleaners may determine whether clients will seek cleaning, and whether cleaners will feed on parasites or attempt to feed on client mucus. The results suggest that cleaning symbiosis is a mosaic of different outcomes driven by geographical differences in the benefits for both participants.

Parasite distribution on client reef fish determines cleaner fish foraging patterns

Recent evidence suggests that cleaner fish Labroides dimidiatus effectively control parasite densities on client reef fish that actively visit them to have parasites and dead or infected tissue removed. These findings support the hypothesis that clients benefit from cleaning, However, they do not show how cleaners reduce the parasite load of their clients. Cleaners could selectively feed on parasites or parasite removal could be a side product of cleaners foraging indifferently on the client surface, resulting in the removal of healthy mucus and scales also. To investigate cleaner fish foraging behaviour, we infected individuals of the surgeon fish Ctenochaetus striatus, with parasitic monogeneans on one body side, while the other body side was parasite free. We then allowed these clients to interact with L, dimidiatus. We found that the duration of interactions depended on parasite load, and that cleaners spent both more time and took more bites per time unit on the infected than on the uninfected side, Our data thus support the idea that parasite abundance determines food patch quality for cleaners. The overall outcome of cleaning interactions is thus likely to benefit the clients.

Spatial distribution of benthic microalgae on coral reefs determined by remote sensing

Understanding the ecological role of benthic microalgae, a highly productive component of coral reef ecosystems, requires information on their spatial distribution. The spatial extent of benthic microalgae on Heron Reef (southern Great Barrier Reef, Australia) was mapped using data from the Landsat 5 Thematic Mapper sensor. integrated with field measurements of sediment chlorophyll concentration and reflectance. Field-measured sediment chlorophyll concentrations. 2 ranging from 23-1.153 mg chl a m(2), were classified into low, medium, and high concentration classes (1-170, 171-290, and > 291 mg chl a m(-2)) using a K-means clustering algorithm. The mapping process assumed that areas in the Thematic Mapper image exhibiting similar reflectance levels in red and blue bands would correspond to areas of similar chlorophyll a levels. Regions of homogenous reflectance values corresponding to low, medium, and high chlorophyll levels were identified over the reef sediment zone by applying a standard image classification algorithm to the Thematic Mapper image. The resulting distribution map revealed large-scale ( > 1 km 2) patterns in chlorophyll a levels throughout the sediment zone of Heron Reef. Reef-wide estimates of chlorophyll a distribution indicate that benthic Microalgae may constitute up to 20% of the total benthic chlorophyll a at Heron Reef. and thus contribute significantly to total primary productivity on the reef.

Can the nitrogenous composition of xylem sap be used to assess salinity stress in Casuarina glauca?

It is predicted that dryland salinity will affect up to 17 Mha of the Australian landscape by 2050, and therefore, monitoring the health of tree plantings and remnant native vegetation in saline areas is increasingly important. Casuarina glauca Sieber ex Spreng. has considerable salinity tolerance and is commonly planted in areas with a shallow, saline water table. To evaluate the potential of using the nitrogenous composition of xylem sap to assess salinity stress in C. glauca, the responses of trees grown with various soil salinities in a greenhouse were compared with those of trees growing in field plots with different water table depths and groundwater salinities. In the greenhouse, increasing soil salinity led to increased allocation of nitrogen (N) to proline and arginine in both stem and root xylem sap, with coincident decreases in citrulline and asparagine. Although the field plots were ranked as increasingly saline-based on ground water salinity and depth-only the allocation of N to citrulline differed significantly between the field plots. Within each plot, temporal variation in the composition of the xylem sap was related to rainfall, rainfall infiltration and soil salinity. Periods of low rainfall and infiltration and higher soil salinity corresponded with increased allocation of N to proline and arginine in the xylem sap. The allocation of N to citrulline and asparagine increased following rainfall events where rain was calculated to have infiltrated sufficiently to decrease soil salinity. The relationship between nitrogenous composition of the xylem sap of C. glauca and soil salinity indicates that the analysis of xylem sap is an effective method for assessing changes in salinity stress in trees at a particular site over time. However, the composition of the xylem sap proved less useful as a comparative index of salinity stress in trees growing at different sites.

Lepocreadiinae lepocreadiids (Digenea) from tetraodontiform fishes in the waters off Tasmania, Queensland and Moorea, French Polynesia

Two new species of Pseudocreadium are described from off northern Tasmania, P maturini sp. nov. from Meuschenia freycineti and P aubreyi sp. nov. from Acanthaluteres vittiger. They differ from the only other recognised species in the genus by the number of ovarian lobes and by size, and they differ from each other by size, shape, caecal length, forebody length, pre-oral lobe size, uterine position, excretory vesicle length and oral sucker shape. Lobatocreadium exiguum is redescribed from Sufflamen bursa, off Moorea, French Polynesia and Abalistes stellatus, Swain Reefs, Great Barrier Reef, Queensland. Records and measurements are given for Hypocreadium cavum from Sufflamen fraenatus and Lepotrema clavatum from Melichthys vidua, both off Heron Island, Great Barrier Reef, Queensland.

Further observations on the Enenteridae Yamaguti, 1958 (Digenea, Lepocreadioidea) of the Indo-West Pacific region, including a new species from Western Australia

Measurements are given for all and full descriptions and illustrations for some of the following enenterid species: Enenterum aureum Linton, 1910 in Kyphosus bigibbus and K. sydneyanus? from Ningaloo Coral Reef, Western Australia, K. vaigiensis from off Heron Island, Queensland and K. vaigiensis from off Moorea, French Polynesia; E. mannarense Hafeezullah, 1980 in K. bigibbus and K. sydneyanus? from Ningaloo Coral Reef; E. elongatum Yamaguti, 1970 in K. vaigiensis from Heron Island, Queensland and K. bigibbus and K. sydneyanus? from Ningaloo Coral Reef; Koseiria alanwilliamsi sp. nov. in Kyphosus cornelii from off Kalbarri, Western Australia; Koseiria xishaense Gu et Shen, 1983 in K. vaigiensis from off Heron Island and K. bigibbus from off Palau, Micronesia; Proenenterum isocotylum Manter, 1954 in Aplodactylus arctidens from off Stanley, Tasmania; R ericotylum Manter, 1954 in A. arctidens from off Stanley; Cadenatella isuzumi Machida, 1993 from Kyphosus bigibbus and K. sydneyanus? from Ningaloo Coral Reef; Cadenatella pacifica (Yamaguti, 1970) from Kyphosus bigibbus from Ningaloo Coral Reef. Two recent cladistic studies of the Enenteridae are discussed and a further analysis has shown that Enenterum and Cadenatella are monophyletic, whilst Koseiria appears polyphyletic. The zoogeography and host-specificity of Kyphosus-inhabiting enenterids is discussed.

Development of preferences for the human body shape in infancy

Two studies investigated the development of infants' visual preferences for the human body shape. In Study 1, infants of 12,15 and 18 months were tested in a standard preferential looking experiment, in which they were shown paired line drawings of typical and scrambled bodies. Results indicated that the 18-month-olds had a reliable preference for the scrambled body shapes over typical body shapes, while the younger infants did not show differential responding. In Study 2, 12- and 18-month-olds were tested with the same procedure, except that the typical and scrambled body stimuli were photographic images. The results of Study 2 again indicated that only the 18-month-olds had a reliable preference for the scrambled body shapes. This finding contrasts sharply with infants' precocious preferences for human faces, suggesting that infants' learning about human faces and human bodies follow different developmental trajectories. (C) 2002 Elsevier Science B.V. All rights reserved.

Patterns of lipid storage and mobilisation in the female green sea turtle (Chelonia mydas)

Reproductive data from southern Queensland indicate that vitellogenesis in female Chelonia mydas takes approximately 8 months and is followed by a migration to a breeding area. At Heron Island, females lay multiple clutches over approximately 3 months. To investigate how females mobilise and store lipid during the breeding season we collected plasma, yolk, and fat tissue samples from females at a variety of stages during the nesting season. In breeding females, concentrations of plasma triglyceride increased seasonally. They reached peak concentrations during vitellogenesis and courtship, remained high throughout the nesting season, and then declined to a nadir after the last clutch. Plasma protein concentration increased throughout the breeding season, peaking following the last clutch for the season. Yolk lipids were highest during courtship and were similar throughout the nesting season, suggesting that uptake of lipid by ovarian follicles is completed prior to the beginning of the nesting season. Plasma triglyceride decreases in females with prolonged periods of unsuccessful nesting, and total lipid levels in adipose tissue and follicle yolks were significantly lower in atretic females. It appears that: (1) endogenous energy reserves can be reduced by stochastic environmental events (such as those reducing nesting success), and (2) a metabolic shift signalling the end of the nesting season is characterised by a drop in plasma triglycerides and slight increase in total plasma protein.

Distribution of a nematocyst-bearing sponge in relation to potential coral donors

Haliclona sp. 628 (Demospongiae, Haplosclerida, Chalinidae), a sponge found on the reef slope below 5 in depth on the Great Barrier Reef, has two unusual characteristics. It contains a symbiotic dinoflagellate, Symbiodinium sp., similar in structure to the dinoflagellate found within Acropora nobilis (S. microadriaticum), and it contains coral nematocysts randomly distributed between the ectosome and endosome and usually undischarged in intact sponge tissue. Given the unusual occurrence of nematocysts in Haliclona sp. 628, the focus of this study was to determine the distribution of this species of sponge on the reef slope at Heron Island Reef in relation to the distribution of potential coral donors. A combination of line and belt transects was used to estimate the abundance of Halielona sp. 628 and a co-occurring congener, Haliclona sp. 1031, which does not contain nematocysts, at three widely separated sites on the reef slope at Heron Island Reef. The abundance of different types of substratum (sand, sand-covered coral rubble, dead A. nobilis, live A. nobilis, other live coral, and other dead coral) along the transects and the substratum to which each sponge colony was attached were also recorded. Despite the predominance of live A. nobilis and sand-covered rubble at all sites, between 30 and 55% of Haliclona sp. 628 colonies were attached to dead A. nobilis which comprised less than 8% of the available substratum along any transect. In contrast, Haliclona sp. 1031 was found significantly more frequently on other dead corals and less frequently on live A. nobilis than would be expected based on the availability of the different substrata in the sites. Potential explanations to account for the distribution of Haliclona sp. 628 in relation to potential coral donors are discussed.

Morphology, ultrastructure, and implied function of ciliated sensory structures on the developmental stages of Merizocotyle icopae (Monogenea : Monocotylidae)

Experimental infections were used to track the fate of the dorsal sensilla of Merizocotyle icopae (Monogenea: Monocotylidae) from nasal tissue of the shovelnose ray, Rhinobatos typus (Rhinobatidae). Scanning and transmission electron microscopy revealed that 3 types of uniciliate dorsal sensilla exist at different times in the development of the monogenean. Type 1 sensilla have little or no invagination where the cilium exits the distal end of the dendrite and possess a ring of epidermis surrounding the cilium distal to the invagination. Type 2 sensilla have a deep invagination where the cilium exits the dendrite. Type 3 sensilla can be distinguished from the other types by the shape of the dendrite. The larvae have predominantly Type I dorsal sensilla, most of which are lost approximately 24 h after infection and a few Type 2 sensilla, which are retained. Additional Type 2 sensilla (termed Adult Type 2 sensilla), which are slightly different morphologically from the Type 2 sensilla of the larvae, form in later stages of development. Numerous Type 3 sensilla are unique to the dorsal surface of adults. Loss of all Type I sensilla upon attachment to the host, R. typus, suggests that these may be chemo- or mechanoreceptors responsible for host location by the swimming infective larvae. Type 2 sensilla appear to be important in the larvae, juveniles, and adults whereas the modality mediated by Type 3 is specific to adults. (C) 2003 Wiley-Liss, Inc.

Species of Stephanostomum Looss, 1899 (Digenea : Acanthocolpidae) from fishes of Australian and South Pacific waters, including five new species

Nine species of Stephanostomum are described from Australian and Southern Pacific marine fishes: Stephanostomum madhaviae n. sp. [syn. S. orientalis of Madhavi ( 1976)] from Caranx ignobilis, off Hope Island, Queensland, with 30-34 circum-oral spines and vitelline fields almost reaching to the posterior extremity of the cirrus-sac; S. bicoronatum (Stossich, 1883) from Argyrosomus hololepidotus, off Southport Broadwater, Queensland; S. votonimoli n. sp. from Scomberoides lysan, off Moorea, French Polynesia ( type-locality) and Western Samoa, with 33-38 circum-oral spines, a uroproct and the vitelline fields not reaching the cirrus-sac; S. nyoomwa n. sp. from Caranx sexfasciatus, off Heron Island, Queensland, with 33-38 circum-oral spines, a uroproct and the vitelline fields reaching the cirrus-sac; S. cobia n. sp. from Rachycentron canadum, off Heron Island, with 36 circum-oral spines, a uroproct and the vitelline fields reaching the cirrus-sac; S. petimba Yamaguti, 1970 from Seriola hippos, off Rottnest Island, Western Australia; S. pacificum ( Yamaguti, 1951) from Pseudocaranx wrighti, off Fremantle, Western Australia; S. aaravi n. sp. from Lethrinus miniatus, off Heron Island, with 36-39 circumoral spines, probably a uroproct and the vitelline fields reaching the ventral sucker; S. pagrosomi ( Yamaguti, 1939) from L. nebulosus, L. miniatus and L. atkinsoni off Heron Island, Pagrus auratus, off Rottnest Island, Western Australia and Gymnocranius audleyi, off Heron Island. A digest of described species of Stephanostomum is included as an appendix.

Lepocreadiidae (Digenea) from the batfish of the genus Platax Cuvier (Teleostei : Ephippidae) from the southern Great Barrier Reef, Queensland, Australia

The following species are described from Platax spp.: Neomultitestis aspidogastriformis n. sp., from P. teira, off Heron Island, Queensland, which can be distinguished from its congeners by the transversely elongate ventral sucker divided into three loculi and probably by testis number; Multitestis magnacetabulum Mamaev, 1970, from P. teira, off Heron Island, Queensland; Diploproctodaeum rutellum ( Mamaev, 1970), from P. teira, off Heron Island, Queensland; Diploproctodaeum tsubameuo n. sp., from P. batavianus, from the Swain Reefs, off Queensland, which differs from its congeners in its overlapping, posteriorly attenuated testes and 38-55 ovarian lobes; and Diplocreadium sp., from P. batavianus, from the Swain Reefs, off Queensland.