The resistance of Crassostrea rhizophorae to starvation and asphyxia

Experiments were performed on the oyster Crassostrea rhizophorae in order to determine the degree of its resistance to conditions of starvation and asphyxia imposed by longlasting transportation. The most favorable results were obtained by lowering the environmental temperature to about 15°C, and keeping the oysters in air, with a daily bath in hypercalcic seawater (Ca content double that of seawater). In this way mortality decreases and energetic reserves are not impaired. Oysters kept in water at their normal environmental temperature, without nutrition, reveal a noticeable increase in mortality and a decrease of about 40% in the glycogen and lipid reserves, during a 15 day starvation period. The normal values of some metabolic and compositional indexes in this species are: oxygen consumption 104±6 cm³ O₂/kg living body weight/h; water content 81±1%; protein content 7.4±0.4%; lipid content 1.6±0.1%; glycogen content 6.0±0.5%. The glycogen is distributed almost uniformly throughout all visceral organs. The oxygen consumption shows no circadial or tidal rhythmicity.With the technical assistance of the students A. Areces, A. Olaechea, M. Oliva, A. Otaso, M. Rodríguez.     

A marine environmental recorder

An inexpensive Marine Environmental Recorder is described. The instrument system is small, lightweight and of low-power consumption. It is flexible, simple to operate and economical. It can be used remotely in a moored, buoyed or towed instrument system, recording measurements continuously for up to 24 h, or intermittently for 1 min every hour, for a period of up to 60 d. It has been used extensively in the Continuous Plankton Recorder and the Undulating Oceanographic Recorder to measure temperature, depth and occasionally chlorophyll and radiant energy; as a temperature recorder, it has a resolution of 0.1 C^o, an uncertainty of measurement of ±0.1 C^o and a stability of calibration within ±0.1 C^o over a period of several months. With optional additional sensors for pitch, roll, vibration, acceleration and water-flow, the instrument system has been used to measure the performance of underwater towed vehicles and plankton samplers. The Marine Environmental Recorder is being incorporated into an instrument system in a data buoy, for automatically monitoring the marine environment in estuaries around the British Isles.     

Effects of in situ tidal salinity fluctuations on osmotic and lonic composition of body fluid in Southeastern Alaska Rocky intertidal fauna

Tidal fluctuations in salinity and temperature were monitored at a location on Lynn Canal, north of Juneau, Alaska. Organisms were collected from 4 tidal levels during each slack water over a period of 24 h. Body-fluid milliosmolality as well as sodium, potassium, calcium, magnesium and chloride levels were determined. Mytilus edulis were collected at the +1.0 m tidal level, where ambient salinity ranged from 7.9 to 25.1% and body fluids from 356±62 to 730±17 mOsm/kg water. Cucumaria vegea and Katherina tunicata were collected at the +0.6 m level, where ambient salinity ranged from 13.5 to 24.9 and body fluids from 461±27 to 662±50 and 443±31 to 616±38 mOsm/kg water, respectively. Eupentacta quinquesemita and Evasterias troschelii were collected at the -0.9 m level, where ambient salinity ranged from 11.0 to 28.2 and body fluids from 504±32 to 632±51 and 316±31 to 664±37 mOsm/kg water, respectively. Strongylocentrotus droebachiensis were collected subtidally at the -3.7 m level, where ambient salinity ranged from 14.1 to 28.0 and perivisceral fluids from 448±35 to 661±51 mOsm/kg water. Ion levels of the perivisceral fluid of c. vegae were not determined. Potassium appeared to be regulated by all animals except Evasterias troschelii. Little regulation occurred for calcium, magnesium, sodium and chloride by the organisms. Eupentacta quinquesemita appeared to be regulating all ions determined, but this may have been due to its microhabitat. Water temperature cycled inversely to salinity at all tidal levels. Ambient-water sodium, chloride and calcium levels deviated from levels that would be expected upon dilution of seawater with deionized water. There was not indication that body-fluid osmoconcentration of the species collected intertidally increased on exposure to air.Communicated by J.S. Pearse, Santa Cruz     

Incidental capture,direct mortality and delayed mortality of sea turtles in Australia's Northern Prawn Fishery

The species composition, catch and mortality rates of sea turtles captured incidentally by the tiger prawn fishery on Australia's northern coast in 1989 and 1990 were estimated by monitoring the fishery's catch. In 1990, the delayed rate of mortality from damage was estimated and the size composition was measured. Five species of turtles were captured: the flatback (Natator depressa, 59% of the total), loggerhead (Caretta caretta, 10%), olive ridley (Lepidochelys olivacea, 12%), green turtle (Chelonia mydas, 8%) and hawksbill (Eretmochelys imbricata, 5%). The turtle catches varied with water depth: the highest catch rates (0.068±0.006 turtles per trawl) were from trawls in water between 20 and 30 m deep, relatively few turtles (10%) were captured in water deeper than 40 m (25% of trawls). Catch rates varied with time of year: the highest catch rates were 0.098 (±0.013) turtles per trawl in winter. There was no significant difference in the overall catch rate (²= 0.047; p=0.8111; df=1) but a significant difference in mortality rate (²= 3.99; p<0.05; df=1) between the two years. The incidence of capture in the commercial fishery was 0.051 (±0.003) turtles per trawl towed for about 180 min, with 0.007 (±0.001) turtles per trawl drowning in the nets. There were no significant differences in the catch and mortality rates between the two years for any of the turtle species except the loggerhead, which had a significantly (² = 11.029; p=0.0013; df=1) lower catch rate in 1990 (0.002±0.001 turtles per trawl) than in 1989 (0.008±0.002 turtles per trawl), and a significantly higher mortality in 1990 (33%) than in 1989 (19%). Catch rates and mortality varied between the species: the flatback had the highest catch rate (0.030±0.002 turtles per trawl) but the lowest mortality (10.9%); the loggerhead had a catch rate of 0.005±0.001 turtles per trawl, and high mortality (21.9%); the olive ridley had a catch rate of 0.006±0.001 turtles per trawl and a low mortality (12.5%); the green turtle's catch rate was 0.004±0.001 per trawl and mortality 12.0%; the hawksbill had the lowest catch rate (0.002±0.001 turtles per trawl) but highest mortality (26.4%). Based on the fishing effort (27 049 d for 1989 and 25 746 d for 1990), we estimate that 5 503 (±424) turtles were caught and returned to the sea in 1989 and 5 238 (±404) in 1990, of which 567±140 drowned in 1989 and 943±187 in 1990. In 1990, an estimated 25% of all captured turtles suffered some non-lethal damage; an estimated 21% of turltes were captured comatose and 4% were injured. We conclude that, considering other threats, trawl-induced drowning is not the major impact on turtle populations in northern Australia, but that measures to reduce drowning and delayed mortality would be desirable.     

The undulating oceanographic recorder — A new instrument system for sampling plankton and recording physical variables in the euphotic zone from a ship underway

The prototype Undulating Oceanographic Recorder Mark I is an instrumented towed vehicle which can be programmed to undulate between a minimum depth of 8 m and a selected maximum depth between 15 and 70 m, with an undulation length between 3 and 30 km, at any speed between 7 and 15 knots (3.6 to 7.7 m/sec). It takes a continuous series of plankton samples, each integrated over the undulation depth range, and records data on magnetic tape, at a preselected rate between 30/min and 30/h, from which salinity, temperature and depth can be derived with accuracies of ±0.1, ±0.1C° and ±0.5 m, respectively. The instrument is automatic, self-contained and generates its own power supplies. It is towed on about 200 m of unfaired steel cable and can be handled with the winching and lifting equipment found on most research vessels. Examples of processed data from three cruises are presented: temperature and salinity contours on a vertical section through a complex stratified area in the N.W. Irish Sea; results from a survey of the waters over the continental shelf and slope to the north of Scotland, showing the distribution of water masses and associated plankton; and hydrographic data taken in Loch Etive on the west coast of Scotland.     

Innovative substrate tiles to spatially control larval settlement in coral culture

We designed settlement tiles for coral culture with the aims: (1) to attract and (2) to spatially control settlement and (3) to produce substrate units for further handling in mariculture. Ceramic tiles with vertical (i.e. pyramid tile; truncated pyramid shape, 22.0×22.0, ±1.0 mm, L×W) and horizontal surfaces (i.e. flat tile; 17.0×17.0, ±1.0 mm, L×W) were temporarily arranged chessboard-like in a polystyrene grid. Surfaces of both types were structured with grooves (width and depth 2.0±0.1 mm). Material analysis by ICP and photospectrometry showed negative influences on water chemistry when new tiles were directly used; high contents of heavy metals could be detected depending on the production process. Planulae of Acropora tenuis (16.3±3.1% settlement) preferred to settle in the grooves of pyramid tiles with a density of 0.19±0.03 to 0.44±0.06 settlers cm^–2, whereas those of Favia fragum (60.7±13.3% settlement) showed high preferences for the grooves of flat tiles (0.48±0.22 to 1.05±0.44 settlers cm^–2). Settlement occurred exclusively on surfaces with a biofilm (turf and crustose coralline algae) and was independent of available substrate surface area, whereas the number of tiles per set-up influenced the density of settlers per unit. Spatial control of settlement was achieved through tile design and arrangement. Tiles with settlers could be easily separated for further use in coral culture.Communicated by O. Kinne, Oldendorf/Luhe     

Gastropod predation on egg cases of skates (Chondrichthyes,Rajidae) in the southwestern Atlantic: quantification and life history implications

Mean predation rates (± SD) on egg cases of the skates Bathyraja macloviana, B. albomaculata, Amblyraja doellojuradoi, and Psammobatis spp. from the southwestern Atlantic were estimated to be 0.151 (±0.230), 0.423 (±0.344), 0.254 (±0.390), and 0.150 (±0.288), respectively. These estimates are within the ranges reported earlier (14–40%). Egg cases of B. albomaculata were preyed on in higher proportion than expected from their abundance and suffered a heavier predation rate where the snail Trophon acanthodes was present. Predation rates were not correlated with the thickness of the egg case wall, which indicates that other factors (ecological or chemical) could explain this pattern. Five types of boreholes were found in the egg cases: one was attributable to muricid gastropods, one to naticid gastropods, and a third type to an unknown gastropod (probably Fusitriton magellanicus); the remaining were of unknown origin. Cladistic analyses showed that skates are secondarily oviparous and have maximized adaptations for living in deep water. We suggest that oviparity in skates appeared as an adaptation to maximize fecundity (40–160 eggs per year, as compared to 2–18 pups annually or biannually in viviparous guitarfishes, the plesiomorphic sister clade of skates). If a predation rate of 24% (the mean of predation rates of all skate species studied to date) is applied to the range of fecundities reported for skates, the result is that 18–114 viable pups are produced annually per female skate. Even with a high mortality rate of 64% (the only direct estimate of natural mortality for any elasmobranch), each female skate produces 17–54 eggs annually. These values are higher than most elasmobranch fecundities. This maximization of fecundity is possible mainly because the fecundity of oviparous species is not limited by body size, as in viviparity. The protracted egg-laying season (4–12 months) of most skates (as in many other deep-sea fishes) maximizes the number of eggs laid.Communicated by P.W. Sammarco, Chauvin     

Mangrove fish-communities in tropical Queensland,Australia: Spatial and temporal patterns in densities,biomass and community structure

Regular daylight sampling over 13 mo (February 1985–February 1986) in and adjacent to intertidal forested areas, in small creeks and over accreting mudbanks in the mainstream of a small mangrove-lined estuary in tropical northeastern Queensland, Australia, yielded 112 481 fish from 128 species and 43 families. Species of the families Engraulidae, Ambassidae, Leiognathidae, Clupeidae and Atherinidae were numerically dominant in the community. The same species, with the addition ofLates calcarifer (Latidae).Acanthopagrus berda (Sparidae) andLutjanus agentimaculatus (Lutjanidae) dominated total community biomass. During high-tide periods, intertidal forested areas were important habitats for juvenile and adult fish, with grand mean (±1 SE) density and biomass of 3.5±2.4 fish m^–3 and 10.9±4.5 g m^–3, respectively. There was evidence of lower densities and less fish species using intertidal forests in the dry season (August, October), but high variances in catches masked any significant seasonality in mean fish biomass in this habitat. On ebb tides, most fish species (major families; Ambassidae, Leiognathidae, Atherinidae, Melanotaeniidae) moved to small shallow creeks, where mean (±1 SE) low-tide density and biomass were 31.3±12.4 fish m^–2 and 29.0±12.1 g m^–2, respectively. Large variances in catch data masked any seasonality in densities and biomasses, but the mean number of species captured per netting in small creeks was lowest in the dry season (July, August). Species of Engraulidae and Clupeidae, which dominated high-tide catches in the forested areas during the wet season, appeared to move into the mainstream of the estuary on ebbing tides and were captured over accreting banks at low tide. Accreting banks supported a mean (±1 SE) density and biomass of 0.4±0.1 fish m^–2 and 1.7±0.3 g m^–2, respectively, at low tide. There were marked seasonal shifts in fish community composition in the estuary, and catches in succeeding wet seasons were highly dissimilar. Comparison of fish species composition in this and three other mangrove estuaries in the region revealed significant geographic and temporal (seasonal) variation in fish-community structure. Modifications and removal of wetlands proposed for north Queensland may have a devastating effect on the valuable inshore fisheries of this region, because mangrove forests and creeks support high densities of fish, many of which are linked directly, or indirectly (via food chains) to existing commercial fisheries.Contribution No. 493 from the Australian Institute of Marine Science     

Growth and content of energy reserves in juvenile sea scallops,Placopecten magellanicus,as a function of swimming frequency and water temperature in the laboratory

The effects of swimming frequency and water temperature on shell growth, tissue mass, and stored energy reserves of juvenile sea scallops, Placopecten magellanicus Gmelin, were examined in a factorial laboratory experiment spanning six weeks in July and August 1992. Individually tagged scallops of similar initial size (22.5±0.1 mm shell height, n=240) were induced to swim to exhaustion at three different swimming frequencies (every day, twice a week, or not at all) in two different water temperature regimes (4 to 7 or 7 to 13°C). The scallops were fed an ad libitum mixture of cultured microalgae. At the end of the experiment, cumulative increase in shell height, dry weight of soft tissues, condition index of dry adductor muscle (adductor muscle dry weight/soft tissue dry weight x 100) and total carbohydrate content of dry adductor muscle were measured for each scallop. Scallops at the higher temperature had significantly greater shell heights, and were in better metabolic condition as evidenced by significantly higher condition indices and muscle carbohydrate contents. The dry soft tissue weights did not differ significantly from their low temperature counterparts. Swimming frequency had no significant effect on shell height, dry tissue weight, or carbohydrate content, but condition index of the adductor muscle increased significantly with swimming frequency. These results show that not only was there no cumulative cost of swimming in terms of shell growth, total soft tissue weight, or carbohydrate content in young scallops, but that condition of adductor muscle tissue was higher in scallops that swam.     

Skeletal Sr content and density in Porites spp. in relation to environmental factors

The coral genus Porites was investigated to evaluate the use of skeletal strontium content as a recorder of seasonal and annual temperature oscillations. In the Hawaiian archipelago, the mean annual water temperature fluctuates by ±0.5C°, with seasonal temperature ranges of 4 to 8C°; the resolution of the Sr thermometer appears to be ±1.5C°. Of this error term, ±0.7C° is analytical, the remainder is biological. Corals from some locations yield temperatures which are consistently offset from the Sr vs temperature calibration line, suggesting genetic population differences. Analysis of cores collected in 1980 from Hawaiian Porites spp. showed no discernible long-term trends over a 100 yr period. Although absolute temperatures are poorly resolved, subannual oscillations in skeletal Sr values accurately reflect recorded seasonal temperature variations. The most useful application of the Sr thermometer is in deciphering the skeletal density band pattern. Subannual oscillations in Sr-temperature values when correlated with density values showed a consistent pattern. When the sections chosen for x-radiography closely followed the growth axis, an abrupt shift from minimum to maximum skeletal density was evident in September/October each year, followed by a gradual decrease in density. The density pattern, shown by microdensitometry, is independent of latitude or temperature range over the Hawaiian archipelago. The annual density shift coincides with high but declining water temperature and solar insolation. If low-density growth represents optimum calcification conditions, the density shift in Hawaiian Porites spp. reflects a change in conditions from optimal to suboptimal. Analyses of samples from other Indo-Pacific locations confirm the generality of this density pattern and suggest a complex relationship between density and environmental light and temperature.Hawaii Institute of Geophysics Contribution No. 1209; Hawaii Institute of Marine Biology Contribution No. 618     

Sperm storage and use in laboratory-reared<Emphasis Type="Italic"> Aplysia californica</Emphasis>, a simultaneous hermaphrodite

Aplysia californica, an opisthobranch mollusc, possesses a complex reproductive system that includes a seminal receptacle for the storage of exogenous sperm received from mating. Based on this reproductive anatomy, A. californica should have the ability to maintain and use viable exogenous sperm stores to fertilize multiple eggmasses for extended periods of time. Using controlled matings and careful observation of the development of eggmasses over time, we attempted to quantify A. californicas ability to store and use exogenous sperm following a single mating. On average, A. californica (240.6±31.7 g; mean±SE, n=9) produced 8.8±0.6 eggmasses containing 16.9±2.2×10⁶ fertilized eggs over a period of 22.3±3.6 days following a single mating encounter. The maximum duration an individual A. californica produced fertilized eggs, following a single copulation, was 41 days. The primary factor determining the cumulative number of fertilized eggs produced from a single mating in A. californica was the mass of the sperm recipient (r=0.773, P<0.05, n=9). Our results demonstrated that A. californica are not sperm limited following a single mating as has been suggested for other opisthobranch molluscs by Leonard and Lukowiaks (1991) gamete-trading hypothesis.Communicated by P.W. Sammarco, Chauvin     

Ferrate(VI) oxidation of ibuprofen: A kinetic study

The kinetics of ferrate(VI) (Fe^VIO₄ ²⁻, Fe(VI)) oxidation of an antiphlogistic drug, ibuprofen (IBP), as a function of pH (7.75–9.10) and temperature (25–45°C) were investigated to see the applicability of Fe(VI) in removing this drug from water. The rates decrease with an increase in pH and the rates are related to protonation of ferrate(VI). The rates increase with an increase in temperature. The E _a of the reaction at pH 9.10 was calculated as 65.4±6.4 kJ mol⁻¹. The rate constant of the HFeO₄ ⁻ with ibuprofen is lower than with the sulphur drug, sulfamethoxazole. The use of Fe(VI) to remove ibuprofen is briefly discussed.     

Changes in morphology and physiology of an East Mediterranean sponge in different habitats

The sponge Tetilla sp. (Tetractinomorpha: Tetillidae) is a common species in the eastern Mediterranean. This sponge inhabits four different habitat types differing in wave impact and irradiance levels. Two of these habitats (a shallow cave and deep water) are characterized by relatively calm water, whereas the other two (shallow exposed site and tide pools) are in turbulent water with high energy flow. The present study examined the influence of physical (depth, illumination and water motion) and biotic factors on morphology, skeletal plasticity and reproductive traits among the four spatially separated populations. Sponges from tidal pools had significantly larger body volume than sponges from deep water and from shallow caves (ANOVA: tidal-deep P<0.0001; tidal-shallow caves P<0.05). Sponges from exposed habitats were significantly larger than deep-water sponges (ANOVA: P=0.01). In addition, individuals from tide pools and from the exposed habitat had a significantly higher proportion of structural silica than sponges from the calmer deep water and from the cave sites. Oxea spicules in sponges from the calm habitats were significantly shorter than in those from the tidal pools and the exposed habitats. The percentage of spicules out of a sponges dry weight in individuals transplanted from deep (calm) to shallow (turbulent) water significantly increased by 21.9±12.9%. The new spicule percentage did not differ significantly from that of sponges originally from shallow water. Oocyte diameter differed significantly between habitats. The maximal size of mature eggs was found in deep-water sponges in June (97±5 m). In the shallow habitats, a smaller maximal oocyte diameter was found in the cave, in May (56.5±3 m). Furthermore, oocyte density in shallow-water sponges was highest in May and decreased in June (with 88.2±9 and 19.3±9 oocytes mm^–2, respectively). At the same time (June), oocyte density of deep-water sponges had just reached its maximum (155±33.7 oocytes mm^–2). The difference in oocyte size and density between deep- and shallow-water individuals indicates an earlier gamete release in the shallow sponge population. The results suggest that plasticity in skeletal design of this sponge indicates a trade off between spicule production and investment in reproduction.Communicated by O. Kinne, Oldendorf/Luhe     

Sexual reproduction and settlement of the coral reef spongeChalinula sp. from the Red Sea

Characteristics of the sexual reproduction and larval settlement of the haplosclerid spongeChalinula sp., which inhabits the shallow waters (1 to 6 m) of Eilat, Red Sea, were investigated from September 1985 through to November 1987. This species was found to be a simultaneous hermaphroditic brooder, hence gonochorism is not the rule in the order Haplosclerida. Brooding always takes place in special brooding chambers. While the oocytes in the brooding chambers are among the largest known in sponges (355±37µm), the spermatic cysts distributed in the choanosome are among the smallest known for this phylum (average 26±7µm).Chalinula sp. breeds throughout the year and in experiments most larvae (74%) settled within 1 to 8 h post-release, generally within 4.5 h. Metamorphosis from larval shape to a sessile sponge lasts 1 to 6 h. Thus, larvae had a short swimming period, settled fast, and metamorphosed rapidly (within 1 to 6 h). The large size of the larvae may contribute to their ability to rapidly reorganize their body shape into that of a sessile sponge. In addition, the existence of already differentiated choanocyte chambers in the larvae, facilitates fast construction of the water filtration system in the newly settled sponges. The reproductive and larval characteristics ofChalinula sp. enable the larvae to settle on any vacant space in the reef, which may explain its abundance in the Red Sea.     

Increased macrophyte nitrate reductase activity as a consequence of groundwater input of nitrate through sandy beaches

While most marine macrophytes preferentially assimilate ammonium to meet growth demand for nitrogen, some also utilize nitrate and exhibit high nitrate reductase activity (NRA). Although nitrate concentrations are often low in coastal waters during the summer and sandy beaches are generally considered to be low nutrient-input habitats, we have observed elevated NRA in leaves of some eelgrass (Zostera marina L.) plants growing immediately adjacent to the shoreline. We postulated that nitrate may become available to eelgrass and macroalgae via groundwater inputs that enter the nearshore water column. To address this possibility, we investigated the availability of groundwater nitrate for the induction of NRA in the leaves of eelgrass and in the macroalgaeSargassum filipendula C. Agardh (Phaeophyceae) andEnteromorpha intestinalis L. Link (Chlorophyceae) collected adjacent to two sandy beaches in the vicinity of Woods Hole, Massachusetts, USA. Induction of NRA was determined in the laboratory for eelgrass collected from one of the beach sites and from an offshore site, Lackey's Bay, which is isolated from groundwater input. At the two beach locations, pore water nitrate concentrations were 100 to 400µM within a few meters inland from the waterline. Nitrate efflux into the nearshore water column was quite high and variable (2160±660µmol m^–2 h^–1) when associated with rapid percolation (37±11 1 m^–2 h^–1) of nitrate-enriched pore water. Turbulent wave mixing rapidly diluted the nitrate. Macroalgae and eelgrass growing adjacent to a beach with high nitrate efflux had NR activities three- to sevenfold higher than those of algae and eelgrass growing along a beach section with low nitrate efflux. NRA of eelgrass plants from Lackey's Bay and Great Harbor increased in response to low daily nitrate additions (10 to 25µM) in the laboratory, with higher nitrate additions (50 to 200µM) yielding less dramatic responses. The increase in NRA was roughly three times higher for Great Harbor than for Lackey's Bay eelgrass. It appears that groundwater input of nitrate is sufficient to induce NRA in marine macrophytes growing near some beaches, including those with turbulent wave mixing.     

Exploratory observations on microhabitat selection within the intertidal zone by the Chinese mudskipper fish Periophthalmus cantonensis

The amphibious Chinese mudskipper fish Periophthalmus cantonensis liver in complex, variable, tropical intertidal mangrove forest and mudlfat habitats. Within these macrohabitats, an array of microhabitats are available to this species which spends most of its time out of water. It is subjected to, and tolerates, wide ranges of salinity and temperature. It is primarily diurnally active and uses dark, usually water-filled burrows in the mud as refuges and breeding places. Individuals of P. cantonensis were captured at night from intertidal mudflats of mangrove forests in the northeastern New Territories, Hong Kong in 1971 and 1972. Using choice experiments in the laboratory, we determined behavioural preferences of this fish for five combinations of abiotic environmental variables relevant to its selections of microhabitats. P. cantonensis usually preferred being out of water, resting on damp mud, to being in direct contact with water of any salinity. In salinity-choice experiments it showed no preference for any particular salinity, but avoided exposure to fresh water. Offered choices between various water temperatures it displayed a strong preference for higher temperatures (30° to 35°C), even though these temperatures were close to those known to cause distress or death. In light-dark choice experiments in very shallow water P. cantonensis preferred darkness to light. Experiments combining watertemperature differences with light-dark choices showed that these two factors interact in complex ways. We discuss implications of these results for understanding of behavioural selection of microhabitats by this fish.     

An assessment of adherence to basic ecological principles by payments for ecosystem service projects

Programs and projects employing payments for ecosystem service (PES) interventions achieve their objectives by linking buyers and sellers of ecosystem services. Although PES projects are popular conservation and development interventions, little is known about their adherence to basic ecological principles. We conducted a quantitative assessment of the degree to which a global set of PES projects adhered to four ecological principles that are basic scientific considerations for any project focused on ecosystem management: collection of baseline data, identification of threats to an ecosystem service, monitoring, and attention to ecosystem dynamics or the formation of an adaptive management plan. We evaluated 118 PES projects in three markets—biodiversity, carbon, and water—compiled using websites of major conservation organizations; ecology, economic, and climate‐change databases; and three scholarly databases (ISI Web of Knowledge, Web of Science, and Google Scholar). To assess adherence to ecological principles, we constructed two scientific indices (one additive [ASI] and one multiplicative [MSI]) based on our four ecological criteria and analyzed index scores by relevant project characteristics (e.g., sector, buyer, seller). Carbon‐sector projects had higher ASI values (P < 0.05) than water‐sector projects and marginally higher ASI scores (P < 0.1) than biodiversity‐sector projects, demonstrating their greater adherence to ecological principles. Projects financed by public–private partnerships had significantly higher ASI values than projects financed by governments (P < 0.05) and marginally higher ASI values than those funded by private entities (P < 0.1). We did not detect differences in adherence to ecological principles based on the inclusion of cobenefits, the spatial extent of a project, or the size of a project's budget. These findings suggest, at this critical phase in the rapid growth of PES projects, that fundamental ecological principles should be considered more carefully in PES project design and implementation in an effort to ensure PES project viability and sustainability.     

Metabolic maintenance costs of the suspension feeder Styela plicata

The bioenergetic basis of the biannual reproductive cycle of the solitary tunicate Styela plicata was investigated in order to evaluate hypotheses concerning the lack of larval settlement in summer. The rate of ingestion and absorption efficiency were measured in order to provide an estimate of the rate at which material was made available for maintenance, growth, and reproduction. At a given temperature the rate of ingestion was proportional to the 0.7 power of wet mass. the ingestion rate increased rapidly with increasing temperature between 12° and 18°C (Q₁₀3), but was independent of temperature between 18° and 28°C. Absorption efficiency was independent of temperature and body size and averaged approximately one-third for both carbon and nitrogen. Metabolic maintenance costs were estimated from measurements of oxygen consumption and excretion of ammonia and urea reported for s. plicata. These require only 18±11% of the carbon and 37±22% of the nitrogen absorbed from the gut of S. plicata over the temperature range 12° to 28°C. Metabolic maintenance makes no excessive demands on the material absorbed in the gut at a particular time of year, and a surplus of carbon and nitrogen substrate is available throughout the year for growth and reproduction. Predation on larvae and young adults may be responsible for the low rate of settlement observed in summer months.     

Lethal and sublethal effects of a simulated salt brine effluent on adults and subadults of the shrimps Penaeus setiferus and P. aztecus

Lethal and certain sublethal effects of salt brines on adults and subadults of two species of penaeid shrimps, Penaeus setiferus and P. aztecus, were examined to evaluate the potential impact of ocean disposal of brine from solution mining of salt domes. Brines, prepared from dome salt or synthetic sea salt diluted with Brazos River (Texas, USA) water or deionized water, were mixed with seawater and dalivered from a proportional diluter to shrimp held (usually) at 25°C. For each combination of species, salt, and diluent, 90-individual trials were conducted in the fall and spring. The effects of temperature were evaluated separately. Median lethal time was strongly dose-dependent: Median lethal concentrations at 48 and 96 h were 654±42 (95% confidence interval) and 540±41 mOsm kg^-1 above ambient seawater, respectively, well above the worst-case predictions for the brine-disposal area. Salt type, diluent type, season or species did not significantly affect brine lethality. Mortality was higher for both species at 30°C and lower for P. setiferus and higher for P. aztecus below 25°C. Lethal brine doses produced tachycardia after 6 (P. setiferus) or 12 h (P. aztecus) of brine exposure. Opacity of abdominal muscles increased with brine concentration. Lethal brine concentrations evoked hyperactivity after 0.75–1.5 h of exposure, significant failure to orient after 6 h and a reduction in general activity after 12 h. Behavior and osmoregulation suggest higher sensitivities to brines made with dome salt or river water and in shrimp tested during the cool seasons.     

Hydrocarbons in benthic algae from the eastern Gulf of Mexico

Thirty-six samples of benthic algae were collected from the continental shelf along the eastern Gulf of Mexico. The algae contain 82.8±143 ppm aliphatic hydrocarbons by dry weight and 11.8±22.7 ppm aromatic and polyolefinic hydrocarbons. The aliphatic constituents of red algae are composed almost entirely of n-C₁₇ (70 to 95% of aliphatic weight); green algae have varying amounts of n-alkanes in the range of n-C₁₅ to n-C₁₉, with homologous series of odd carbon number n-alkenes. Phytadienes occur as high as 740 ppm dry weight in the green algae and do not appear to be related to time or place of collection or to presence of any petroleum pollutants. The single brown algal species contains predominantly n-C₁₅. About 30% of the samples have hydrocarbons resembling degraded petroleum residues, but no petroleum pollution of recent origin was detected in any specimen.