Large-scale spatial variation in epilithic algal matrix cryptofaunal assemblages on the Great Barrier Reef

Spatial variation in the epilithic algal matrix (EAM) cryptofauna was investigated at three locations on the Great Barrier Reef: two inner shelf—Orpheus Island and the Turtle Island group—and a mid-shelf location, Lizard Island. Although the EAM appears to be a relatively simple and consistent habitat, significant differences in cryptofaunal assemblages were found between locations. EAM assemblages from Orpheus Island were markedly different. This appears to be a function of the sediment profile characteristics (grain size >60 µm) at Orpheus Island, as many cryptofaunal taxa displayed positive relationships with sediment volume. However, sediment volumes did not differ significantly between the three locations, highlighting the possibility of cyclonic activity affecting the sediment profile at Orpheus Island in the months preceding the study, in addition to the nutrient input from major terrigenous sources. The results of this study show that EAM cryptofaunal assemblages are not uniform across the Great Barrier Reef and suggest that dissolved nutrients, sediment loads and distance from river systems may be significant drivers of cryptobenthic faunal compositions.     

Lipids and fatty acid composition of particulate matter in the North Atlantic: importance of spatial heterogeneity,season and community structure

Lipid class profiles and total fatty acid composition of particulate matter were studied in the northeast Atlantic during the spring bloom and fall. Eddies of known physical and chemical properties were sampled at different depths. HPLC pigment data were used to characterize the phytoplankton communities. In spring, a dominance of prymnesiophytes was recorded at all depths, while in fall prochlorophytes dominated near the surface and prymnesiophytes only at deep chlorophyll maximum. Lipid classes included triglycerides, sterols, glycolipids and phospholipids. A differential relationship between phytoplankton abundance and lipid accumulation was observed: spring lipid concentrations were positively related to phytoplankton biomass, while fall particulate lipid did not show any relationship. The main feature was a northward increase in lipid concentrations unrelated to the mesoscale hydrological structures. Polar lipids dominated over neutral acyl-glycerols with phospholipids dominating over glycolipids in spring, while glycolipids dominated in fall. This resulted from different nutrient availability with a dominance of flagellates associated with mesotrophy in spring and of picophytoplankton associated with oligotrophy in fall. In terms of fatty acids, factorial correspondence analyses illustrate the influence of seasonally changing assemblages: (1) in spring, the main source of variability was the bloom with an opposition between bloom sites characterized by n-3 and n-6 PUFA, and more detrital deep samples characterized by saturated, monoenoic and branched acids; (2) fall fatty acid profiles were similar at all depths and very close to those observed for spring deep samples. Comparison of pigment and fatty acids using redundancy analysis suggested that pelagophytes were linked to saturated and branched acids. It also showed that prymnesiophytes and prochlorophytes were significantly associated with n-6 and n-3 PUFA. The spring period illustrated the complexity of these relationships with dinoflagellates and prymnesiophytes linked with n-3 PUFA, diatoms linked with palmitoleic and myristic acids, and pelagophytes linked with n-6 PUFA and higher-chain-length monoenes.     

Enhanced organic phosphorus detection in sediments by foam separation and 31P-NMR

Phosphorus (P) is both a nutrient and a pollutant. For instance, excess P induces water eutrophication followed by death of fishes and other water life. Determination of organic P content in sediments is therefore important to study P cycling and environmental pollution. The most widely used method to determine organic P in sediments is NaOH–EDTA extraction followed by ³¹P-NMR detection. However, some organic P compounds are difficult to extract using NaOH–EDTA due to the low solubility, thus can not be detected by ³¹P NMR. Here, we used foam separation to determine organic P in sediment of North Canal of Tianjin City, China. Organic P was first enriched using foam separation coupled with NaOH extraction. The enriched organic P was then analyzed with ³¹P NMR. The results showed that, compared with the traditional extraction method, foam separation coupled with NaOH extraction enriched more P compound because ³¹P NMR detected an extra signal of teichoic acid at chemical shift 1.14. This teichoic acid signal was not detected in the extract prepared using only NaOH–EDTA. Our finding demonstrates that determination using foam separation followed by ³¹P NMR is feasible.     

Dimethyl disulfide and dimethyl trisulfide: so similar yet so different in evoking biological responses in saprophilous flies

Dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) are used by saprophilous insects to locate breeding sites (decaying organic matter), and by brood-site deceptive flowers to attract such insects. However, little is known about the relative importance of these two compounds in eliciting electrophysiological and behavioral responses in the insects. Here, we compared the relative attractiveness of DMDS and DMTS to saprophilous flies in field choice experiments and tested whether potential differences in field responses can be explained by differences in electrophysiological antennal responses to these compounds. Field experiments revealed that the attractiveness of a mixture of these compounds is due to DMTS alone. This result was confirmed by electroantennographic recordings in which flies of four tested species of Calliphoridae (Lucilia sericata, L. caesar, Calliphora vicina, Protocalliphora azurea) and one Muscidae (Musca domestica) respond clearly to DMTS, but not to DMDS. In house flies, however, DMTS elicited electrophysiological responses only, not reflected in behavioral assays. Despite the fact that DMTS and DMDS exhibit similar chemical structures, both the electroantennographic and field responses from saprophilous flies to these two compounds strongly differed. Our study suggests that oligosulfide-responsive saprophilous flies rely on DMTS and not DMDS for finding appropriate breeding sites and that DMTS and not DMDS could act as a key mediator for pollinator attraction in brood-site deceptive plants.     

Effects of gamma-aminobutyric acid on the settlement of larvae of the black chiton Katharina tunicata

Laboratory-cultured larvae of the black chiton Katharina tunicata (Wood), collected from central California in May and June of 1979 and 1980, settled preferentially on the encrusting coralline alga Lithothamnium sp. Metamorphosis, which involves the loss of the prototrochal ciliary band, occurred within a period of 2.5 h after larvae began crawling upon the alga. In response to gamma-aminobutyric acid (GABA) at a concentration of 10^-6 M, the lecithotrophic trochophore larvae ceased swimming and settled rapidly. Developmental metamorphosis did not follow settlement in the absence of encrusting coralline alga. However, when both GABA and Lithothamnium sp. were present, larval metamorphosis occurred within 2 h of settlement. Significantly different rates of settlement exist for sibling larvae of different ages; 12 d-old larvae responded more rapily and in greater numbers to treatment with GABA than 10 d-old larvae. Differences in settling rates are attributed to the onset of metamorphic competence.     

A light and electron microscope investigation of gametogenesis in Nicolea zostericola (Polychaeta: Terebellidae)

A light and electron microscope study was conducted on Nicolea zostericola (Oersted: Grube, 1860) to describe the processes of gametogenesis. N. zostericola is a monotelic species which spawns from 2 to 5 times over a period of 2 weeks at the end of its 1-year life span. The gonads consist of plates of cells bulging from beneath the peritoneum in the thoracic region of the body. Oogenesis has been divided into 3 phases: an ovarian phase in which gametogonia and primary oocytes are retained within the ovary, a follicular phase, in which oocytes are ovulated into the coelom surrounded by several layers of follicle cells and the vitellogenic phase, where individual oocytes rupture through the follicle cells and enter the coelomic fluid where cell growth and yolk synthesis occur. The combined ovarian and follicular phases have a duration of about 3 to 5 weeks and the vitellogenic phase about 5 to 6 months. Vitellogenesis is described on the ultrastructural level. Yolk synthesis involves the participation of the Golgi apparatus and endoplasmic reticulum of the oocyte in possible combination with nutrient absorption from the coelomic fluid. Spermatogenesis involves the rupturing of masses of spermatogonia into the coelom from the testis, surrounded by peritoneal cells. Smaller clusters of spermatocytes are later released into the coelomic fluid where mitotic and meiotic divisions eventually produce flattened plates of sperm. The mature spermatozoan possesses an elongate head, atypical for most polychaetes.     

Resin embedments of quantitative meiofauna samples for ecological and structural studies — Description and application

In enumerating data for systematic and ecological studies on meiofauna, an unfortunate diversification exists in the methods used for observation, identification, preservation and curatorial treatment of various taxa. The application of transmission electron microscopy resin embedment techniques to whole, quantitative, extracted meiofauna samples is described here as a new method, which overcomes most of these problems. Slide-shaped resin blocks are produced by this method; they contain the mass-embedded meiofauna on one side and sand from the sample site on the other side; the latter can be used in studying sand-grain epigrowth of Protista, Fungi and Monera. Examples for the applicability of these slides to various meiobenthic studies are given for most taxa, but especially for Turbellaria, Annelida and Mystacocarida. Using this resin-slide technique, whole quantitative transects can be deposited as “ecotype material” in museums.     

Hierarchical modeling of abundance in closed population capture–recapture models under heterogeneity

Hierarchical modeling of abundance in space or time using closed-population mark-recapture under heterogeneity (model \(\hbox {M}_{\text {h}}\) ) presents two challenges: (i) finding a flexible likelihood in which abundance appears as an explicit parameter and (ii) fitting the hierarchical model for abundance. The first challenge arises because abundance not only indexes the population size, it also determines the dimension of the capture probabilities in heterogeneity models. A common approach is to use data augmentation to include these capture probabilities directly into the likelihood and fit the model using Bayesian inference via Markov chain Monte Carlo (MCMC). Two such examples of this approach are (i) explicit trans-dimensional MCMC, and (ii) superpopulation data augmentation. The superpopulation approach has the advantage of simple specification that is easily implemented in BUGS and related software. However, it reparameterizes the model so that abundance is no longer included, except as a derived quantity. This is a drawback when hierarchical models for abundance, or related parameters, are desired. Here, we analytically compare the two approaches and show that they are more closely related than might appear superficially. We exploit this relationship to specify the model in a way that allows us to include abundance as a parameter and that facilitates hierarchical modeling using readily available software such as BUGS. We use this approach to model trends in grizzly bear abundance in Yellowstone National Park from 1986 to 1998.     

Effects of habitat fragmentation on the genetic structure and connectivity of the black-lipped pearl oyster Pinctada margaritifera populations in French Polynesia

Habitat destruction leading to increased fragmentation is detrimental to species by reducing population size and genetic diversity and by restraining population connectivity. However, little is known about the effects of naturally fragmented habitats on wild populations, especially when it comes to marine benthic invertebrates with long pelagic larval duration. In this framework, we investigated the connectivity and genetic diversity variation among nine wild populations of the black-lipped pearl oyster, Pinctada margaritifera, throughout French Polynesia using ten microsatellite DNA markers. Despite the naturally fragmented habitat (South Pacific oceanic islands), we found high values of genetic diversity and population admixture, indicating connectivity at small and large spatial scales within sampled sites of the Tuamotu, and between the Society and Tuamotu Archipelagos. In the meantime, habitat geomorphology increased genetic drift in populations occurring in small, closed lagoons. Significant genetic structure not correlated to geographic distance was detected mainly between closed and open lagoons. The Marquesas Islands hosted the most divergent populations, likely a result of vicariance. Our results also highlight that migration patterns among lagoons are not symmetrical. Altogether, the general pattern of gene flow, nonsymmetrical migration rates among populations, absence of isolation by distance and absence of recent extinction events found in our study strongly suggest that P. margaritifera populations of French Polynesia follow an asymmetrical island model of dispersal.     

Reducing the environmental impact of coal-washing practice in Australia

All Australian coal for export is washed — that is, the low-grade high-ash material is separated out and disposed of at the washery site. The coarse rejects are generally placed in embankments and the tailings are pumped into settling ponds. These methods of waste disposal can create environmental problems. In addition, they represent a significant energy loss, because about one-third of the waste material is combustible and is thus a potentially valuable source of energy. Laboratory studies at the CSIRO Division of Fossil Fuels at North Ryde, New South Wales, have shown that energy can be successfully recovered from washery wastes by the process of fluidized-bed combustion. A pilot fluidized-bed combustor, with a capacity of 2 tonnes/hour, is undergoing prolonged trial at the Clutha washery near Camden, New South Wales, in a joint project between the Joint Coal Board and CSIRO. The results from the pilot plant tests have provided the basis for a conceptual design and feasibility study for a full-scale tailings treatment plant. This study has indicated that fluidized-bed combustion:

1. offers an environmentally attractive and economically competitive alternative to the disposal of tailings in settling ponds, and
2. can be used to generate large quantities of energy from the wastes, reducing the energy lost in coal washing from around 16% to 6% of the coal mined.

     

Molecular characterization of symbiotic algae (Symbiodinium spp.) in soritid foraminifera (Sorites orbiculus) and a scleractinian coral (Orbicella annularis) from St John,US Virgin Islands

The exchange of Symbiodinium symbionts among scleractinian and soritid hosts could facilitate acclimatization to changing conditions by establishing novel symbiotic unions better tuned to prevailing conditions. In this study, we compare the communities of Symbiodinium spp. in neighboring populations of Orbicella annularis and Sorites orbiculus from St. John, US Virgin Islands, using operational taxonomic unit (OTU) clustering of cloned internal transcribed spacer 2 (ITS-2) rDNA sequences. We tested for partitioning of Symbiodinium OTUs by host and depth within and between two sites to explore the potential for symbiont exchange between hosts and light-dependent microhabitat specialization. An apparent lack of overlap in Symbiodinium communities (13 OTUs representing 7 clades) hosted by O. annularis and S. orbiculus suggests that exchange among these hosts does not occur. A low number of novel clade G ITS-2 sequences were found in one O. annularis and one S. orbiculus. A phylogenetic analysis of these sequences revealed them to be sub-clade G2 Symbiodinium, which are most commonly hosted by excavating clionid sponges. A permutational MANOVA revealed within host differences in the partitioning of Symbiodinium OTUs by site but not depth. This finding highlights the potential roles of either dissimilar environmental conditions between sites, or at least partial separation between populations, in determining the types of Symbiodinium contained in different hosts on a spatial scale of a few kilometers.     

Comparison of sterol composition of some Baltic Sea and Black Sea mussels

Sterol composition of three Baltic Sea mussels (Mytilus edulis, Cardium glaucum, Mya arenaria) was compared with the sterol composition of three biologically closely related mussels from the Black Sea (Mytilus galloprovincialis, Cardium edule, Mya arenaria). The qualitative sterol composition of the mussels studied was similar, but some quantitative differences were found.     

Isolation of a new toxin from the sponge Latrunculia magnifica in the Gulf of Aquaba (Red Sea)

The sponge Latrunculia magnifica was found to be toxic for fish. A toxin has been isolated from this sponge by organic extraction-column chromatography and thin-layer chromatography. Several chemical properties of the toxin were determined by spectroscopic analysis. Toxicity tests were performed on the fish Gambusia affinis. In vitro experiments showed the toxin to be a cholinesterase inhibitor.     

Toxicity of ammonia,nitrite ion,nitrate ion,and orthophosphate to Mercenaria mercenaria and Crassostrea virginica

The 96-h lethal tolerance limits of the hard clam Mercenaria mercenaria (Linné) and the oyster Crassostrea virginica (Gmelin) to ammonia, nitrite ion, nitrate ion, and orthophosphate were defined. Sublethal effects of the chemicals upon the rates at which the shellfish removed algal cells from suspension were also studied. In comparison with other marine and aquatic species which have been studied, hard clams and oysters are extremely tolerant.     

Ecology of the northern Red Sea crinoids and their Epi- and Endozoic fauna

Fourteen crinoid species are found along the coral reefs of the northern Red Sea that form aggregations of different species at various depths. The shallowest aggregation consists partly of Lamprometra klunzingeri and Capillaster multiradiatus, occurring subtidal to a depth of 2 to 5 m. Of this group, Heterometra savignii inhabits depths down to 12–15 m. Further down, another group of 10-armed crinoids occurs, dominated by Decametra chadwicki and Oligometra serripinna. The deepest aggregation of crinoids occurs at 45 m; its most common members are Colobometra arabica and Comaster distinctus. Feeding on micro- and nanoplankton, shallow-water crinoids show a circadian activity rhythm; in deeper aggregations (10 to 12 m), this behaviour changes with decreasing illumination, to a diurnal activity rhythm. The symbiotic animals living on crinoids comprise 27 taxons, among them Copepoda (6 species), Mollusca (2 species), Polychaeta (11 species, especially Myzostomida); Ophiurida (1 species), Crustacea, Decapoda (6 species); and the clingfish Lepadichthys lineatus. These symbiotic animals form food webs at various depths, according to the distribution of their crinoid host. The occurrence of Indo-West Pacific and Mediterranean commensals on the same crinoid in the Gulf of Aqaba is of special interest.     

Localization and biochemical characterization of pharyngeal protease in the polychaetous annelid Glycera convoluta

In Glycera convoluta Keferstein, pharyngeal protease is secreted by the glandular epithelial cells, as clearly demonstrated by microscopic observation of the digestion of a prestained gelatin film by fresh tissue sections of the organ. The enzyme, extracted by affinity chromatography on Sepharose-?-aminocaproïc-D-tryptophan, acts on substrates hydrolyzable by α-chymotrypsin such as N-benzoyl-L-tyrosine ethyl ester and carboxyl-propionyl-phenylalanine-p-nitroanilide, and can be considered as a chymotrypsin-like enzyme.     

New epizooic symbioses between sponges of the genera Plakortis and Xestospongia in cryptic habitats of the Caribbean

Three new cases of sponge symbiosis between species of Plakortis and Xestospongia were found in reef caves and mesophotic reef habitats of the Caribbean. Plakortis sp. 1 from the Bahamas associates exclusively with Xestospongia deweerdtae which was originally described living freely on the deep fore-reef and caves of Jamaica. In addition, we found Plakortis sp. 2 from Puerto Rico which associates with both X. deweerdtae and a different Xestospongia sp. Sponge specimens were identified using cytochrome oxidase subunit 1, 28S rRNA and 18S rRNA gene sequence fragments, spicule analysis, and histological sections with SEM. Unlike previous sponge pairs, Xestospongia spp. not only grew as a thin veneer of tissue over the Plakortis host sponge but through the mesohyl, forming inner channels (0.1–1 cm) that may provide a benefit by facilitating more efficient water transport through the dense Plakortis tissue. Symbioses with both Plakortis spp. were documented from an early recruit stage through adulthood. Spicule measurements conducted on symbiotic versus free-living X. deweerdtae revealed significantly smaller spicule sizes for symbiotic individuals, suggesting a cost in terms of silicon availability, or a benefit in terms of a lower investment in skeleton synthesis for support. This study reveals new specialized symbiotic associations between distantly related sponge genera that likely represent an alternative strategy of adaptation for life in reef caves and mesophotic reefs.     

Density and composition of heterotrophic bacterial populations in North Sea sediments

The bacteria from 119 sediment samples collected off the Belgian and Dutch North Sea coast were enumerated on marine agar. Geographical and seasonal variations were observed. The colony formers were mainly obligate aerobes. Coliform organisms were relatively rare. An exhaustive analysis of a few samples revealed a great number of species belonging to different taxonomic groups. A survey of physiological and biochemical characteristics of 71 isolates is presented.     

Assimilation,inter-organ transfer and excretion of americium in two teleost fish

Radiotracer experiments were performed (February–April, 1982) to study the assimilation and metabolism of the transuranium nuclide americium-241 in the marine teleosts Serranus scriba (Linnaeus, 1758) and Scorpaena notata Rafinesque, 1810, caught off the Monaco coast. Fish fed with ²⁴¹Am-labelled food showed that assimilation of this radionuclide takes place through the gastrointestinal walls and that the small fraction accumulated is incorporated mainly in the skin, muscle and skeleton. Gut-transfer coefficients were similar in both species and averaged 0.7% (range 0.1 to 1.7%) of the ingested activity. The calculated biological half-lives for loss of the absorbed fraction ranged between 49 and 61 d for Serranus scriba and 12 and 117 d for Scorpaena notata. Results from an intramuscular injection experiment indicated that ²⁴¹Am was retained mainly in the liver, skin and skeleton; the fraction accumulated by muscle was very low. Liver displayed a relatively short biological half-time for ²⁴¹Am loss of roughly 24 d. Routes of ²⁴¹Am excretion from the teleosts appear to be through the kidneys, gills and feces with bile serving as a possible excretion route from the liver. From the limited amount of published information available for comparison, experimental evidence is presented which suggests that ²⁴¹Am taken up via the food chain is more biologically available to marine fish than is plutonium.