Marc Slattery

Aquatic ecotoxicology of fluoxetine.

Recent studies indicate that the pharmaceutical fluoxetine, a selective serotonin reuptake inhibitor, is discharged in municipal wastewater treatment plant effluents to surface waters. Few data on environmental fluoxetine exposure and hazard to aquatic life are currently available in the literature. Here, we summarize information on fluoxetine detection in surface waters and review research on single-species toxicity test, Japanese medaka (Oryzias latipes) reproduction and endocrine function, and freshwater mesocosm community responses to fluoxetine exposure. Based on results from our studies and calculations of expected introduction concentrations, we also provide a preliminary aquatic risk characterization for fluoxetine. If standard toxicity test responses and a hazard quotient risk characterization approach are solely considered, little risk of fluoxetine exposure may be expected to aquatic life. However, our findings indicate that: (1) the magnitude, duration and frequency of fluoxetine exposure in aquatic systems requires further investigation; (2) mechanistic toxicity of fluoxetine in non-target biota, including behavioral responses, are clearly not understood; and (3) an assessment of environmentally relevant fluoxetine concentrations is needed to characterize ecological community responses.

Waterborne and sediment toxicity of fluoxetine to select organisms

Ecological risk assessments of pharmaceuticals are currently difficult because little-to-no aquatic hazard and exposure information exists in the peer-reviewed literature for most therapeutics. Recently several studies have identified fluoxetine, a widely prescribed antidepressant, in municipal effluents. To evaluate the potential aquatic toxicity of fluoxetine, single species laboratory toxicity tests were performed to assess hazard to aquatic biota. Average LC(50) values for Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas were 0.756 (234 microg/l), 2.65 (820 microg/l), and 2.28 microM (705 microg/l), respectively. Pseudokirchneriella subcapitata growth and C. dubia fecundity were decreased by 0.044 (14 microg/l) and 0.72 microM (223 microg/l) fluoxetine treatments, respectively. Oryias latipes survival was not affected by fluoxteine exposure up to a concentration of 28.9 microM (8.9 mg/l). An LC(50) of 15.2 mg/kg was estimated for Chironomus tentans. Hyalella azteca survival was not affected up to 43 mg/kg fluoxetine sediment exposure. Growth lowest observed effect concentrations for C. tentans and H. azteca were 1.3 and 5.6 mg/kg, respectively. Our findings indicate that lowest measured fluoxetine effect levels are an order of magnitude higher than highest reported municipal effluent concentrations.

Chemical defenses in Antarctic soft corals: evidence for antifouling compounds

Organic extracts from the antarctic soft corals Alcyonium paessleri May and Gersemia antarctica Kukenthal exhibited antimicrobial and antifoulant activity. A third antarctic soft coral, the stoloniferan Clavularia frankliniana Roule, exhibited no such bioactivity. Marine bacterial attachment was inhibited in the presence of chloroform and aqueous methanol extracts of A. paessleri and G. antarctica, but not in the presence of solvent controls. Similarly, inhibition of microbial growth in three sympatric species of antarctic marine bacteria occurred in response to aqueous methanol extracts of these two soft corals, but not to the controls. Antifoulant activity of chloroform extracts of A. paessleri and G. antarctica was detected in a month-long field assay measuring inhibition of benthic diatom settlement. Observed invertebrate recruitment rates were too low to allow an evaluation of antifoulant bioactivity. Laboratory growth experiments, employing the antarctic diatom Navicula sp. and larvae of the antarctic sea urchin Sterechinus neumayeri Meissner, confirmed the presence of growth-inhibiting metabolites in the soft corals A. paessleri and G. antarctica. These results suggest that both A. paessleri and G. antarctica, which do not appear to be fouled in the field, possess bioactive compounds with antifoulant activity. In contrast, C. frankliniana, which is often heavily fouled, appears to lack antifouling compounds.

Photoacclimatization by the coral Montastraea cavernosa in the mesophotic zone: light, food, and genetics

Most studies on coral reefs have focused on shallow reef (< 30 m) systems due to the technical limitations of conducting scientific diving deeper than 30 m. Compared to their shallow-water counterparts, these mesophotic coral reefs (30-150 m) are understudied, which has slowed our broader understanding of the biodiversity, ecology, and connectivity of shallow and deep coral reef communities. We know that the light environment is an important component of the productivity, physiology, and ecology of corals, and it restricts the distribution of most species of coral to depths of 60 m or less. In the Bahamas, the coral Montastraea cavernosa has a wide depth distribution, and it is one of the most numerous corals at mesophotic depths. Using a range of optical, physiological, and biochemical approaches, the relative dependence on autotrophy vs. heterotrophy was assessed for this coral from 3 to 91 m. These measurements show that the quantum yield of PSII fluorescence increases significantly with depth for M. cavernosa while gross primary productivity decreases with depth. Both morphological and physiological photoacclimatization occurs to a depth of 91 m, and stable isotope data of the host tissues, symbionts, and skeleton reveal a marked decrease in productivity and a sharp transition to heterotrophy between 45 and 61 m. Below these depths, significant changes in the genetic composition of the zooxanthellae community, including genotypes not previously observed, occur and suggest that there is strong selection for zooxanthellae that are suited for survival in the light-limited environment where mesophotic M. cavernosa are occurring.

Larval settlement and juvenile survival in the red abalone (Haliotis rufescens), an examination of inductive cues and substrate selection

Abstract Settlement and metamorphosis of red abalone, Haliotis rufescens , larvae were examined in the presence of three inductive settlement cues (conspecific mucus, a sympatric diatom assemblage, and γ-aminobutyric acid). All experiments were conducted without the use of antibiotics. Larval settlement success differed significantly with substrate type. Mucus from juvenile H. rufescens yielded the highest levels of successful larval settlement. Larval settlement success varied and was highest between August and mid-September when examined from late spring (May) to early winter (December). Larval metamorphosis and juvenile survival to appearance of the first respiratory pore also varied with substrate type. After 11 weeks, approximately 53, 84, and 100% of the larvae had suffered mortality on substrates of conspecific mucus and diatoms, diatoms, and γ-aminobutyric acid and diatoms, respectively. In all treatments, an initial high rate of juvenile mortality and reduced rates of juvenile development suggested abalone were nutrient-limited. High larval settlement rates and survival of juvenile H. rufescens on substrates of conspecific mucus indicate that this inductive cue may be of significance in situ as well as offering a convenient methodology for the rearing of red abalone in mass-culture systems.

Chemical signals in gametogenesis, spawning, and larval settlement and defense of the soft coral Sinularia polydactyla

Abstract Mass spawning strategies of hard and soft corals on the Great Barrier Reef, Australia have been described in recent years. Nonetheless, the applicability of those studies to corals on other reef systems has not been well documented. Here we describe the mass spawning behavior of the soft coral Sinularia polydactyla on coral reefs surrounding Guam; specifically we describe the events in an annual gametogenic cycle including steroidogenesis, spawning, settlement and early life history defense. The gametogenic cycle of female colonies lasted 12 months while male colonies produced viable sperm within 9 months. Sinularia polydactyla exhibited a split spawn between March and June that correlated with a significant reduction in tissue concentrations of progesterone and testosterone. Estradiol was released into the water column, apparently by female colonies, just prior to spawning. There was a trend for preferential larval settlement in the presence of the crustose coralline algae Hydrolithon reinboldii rather than coral rubble, a natural biofilm, or filtered seawater. The defensive compounds pukalide and 11β-acetoxypukalide were found in eggs and larvae at adult level and three-fold lower than adult-level concentrations, respectively. These compounds provided some predator deterrent and antimicrobial protection against an ecologically relevant omnivorous fish Canthigaster solandri and a sympatric microbe Vibrio sp.

Terpenoids of Sinularia.: Chemistry and Biomedical Applications

Abstract The soft coral genus Sinularia. is one of the most widely distributed soft corals. It constitutes a dominant portion of the biomass in the tropical reef environment. Sinularia. elaborates a rich harvest of secondary metabolites including sesquiterpenes, diterpenes, polyhydroxylated steroids, and polyamine compounds. These metabolites were recently shown to possess a range of biological activities such as antimicrobial, anti-inflammatory, and cytotoxic activities. During the past decade, Sinularia. has yielded many new structures with novel skeletons. Several of the previously published secondary metabolites have been reexamined for their pharmacological properties, and the results strongly support further investigations. The current article reviews the terpenoids of the soft coral genus Sinularia. and their pharmacological significance.

Biochemical and energetic composition, population biology, and chemical defense of the antarctic ascidian Cnemidocarpa verrucosa lesson

Abstract The biochemical and energetic composition, population biology (size-weight relationship, abundance and size-frequency distribution) and chemical defense of the antarctic ascidian Cnemidocarpa verrucosa Lesson was investigated at McMurdo Sound, Antarctica, during the austral summer of 1989. The organic content (% organic material · g −1 dry tissue wt) of individual body components (tunic, body wall, endocarps, intestines, mature ovitestes and branchial basket) was generally high, with values ranging from 44.5% in the endocarps to 83.9% in the gonads. Most of this material was in the form of NaOH-soluble and insoluble protein. Tissue energy values ranged from 15.1 (tunic) to 22.4 (gonad) kJ · g −1 dry wt. Body height (cm) was positively related to body weight (g dry wt) by an exponential function. A representative individual (14 cm height, 550 g wet wt) contained a total of 493 kJ with most (75%) of this energy attributable to the body wall and tunic. The gonadal index [(kJ ovitestes · total kJ −1 ) x 100] for sexually mature individuals collected in November was 17.2 ± 4.7 ( n = 6). Population densities of C. verrucosa at depths of 20–30 m were 0.4 ind · m −2 at a site 3 km north of McMurdo Station. Energetic densities were estimated to be 197 kJ · m −2 . Size-frequency analysis revealed four modal peaks that probably represent distinct age cohorts, and may indicate predictable, annual recruitment events. Bioassays revealed that the tunic was noxious to sympatric pelagic and benthic fish, as well as an allopatric model fish. However, aqueous tunic extracts did not cause mortality in sea urchin sperm indicating the noxious compound(s) is not cytotoxic. pH values for body components were weakly acidic or neutral (5.86–6.93). Mature ovitestes were rejected by sympatric pelagic fish suggesting that gametes may be chemically defended. Although this common antarctic ascidian represents a significant resource of materials and energy, its tunic is tough and noxious, and probably provides an effective means of defense against potential predators.

Energetic composition, biomass, and chemical defense in the common antarctic nemertean Parborlasia corrugatus McIntosh

Abstract Parborlasia corrugatus McIntosh is a large, abundant, epibenthic antarctic nemertean which represents a considerable source of nutrition for predators. The energetic composition of adult body tissues (kJ·g −1 dry wt) is comprised primarily of energy derived from protein (11.4 kJ NaOH-insoluble, 6 kJ NaOH-soluble). Energy units associated with lipid (4.3 kJ) and carbohydrate (0.2 kJ) are much lower. Based on calculations of the energetic composition of whole body tissues, and a density of 0.3 ind·m −2 , mean population energetic density is estimated to be 65 kJ·m −2 . These values are often significantly higher as P. corrugatus aggregates when feeding. Despite their high abundance, nemerteans are not preyed upon and appear to be chemically defended. Sperm of the antarctic sea urchin Sterechinus neumeyeri (Meissner) were killed when exposed to a 3% aqueous extract of whole nemertean body tissues. In laboratory feeding experiments, two common species of antarctic fish showed significant rejection of nemerteans. Its toxic and feeding-deterrent characteristics are probably the result of the epithelial production of copious acidic mucus (pH = 3.5), although other toxic or noxious metabolites may be present. These results indicate that P. corrugatus , an important scavenger in antarctic benthic systems, is abundant, high in nutrients and energy content, and could be judged on this basis as a high-quality prey item. Nonetheless, due to its chemical defense, potential predators may avoid ingestion of this species.

Genetic structure in the coral, Montastraea cavernosa: assessing genetic differentiation among and within Mesophotic reefs.

Mesophotic coral reefs (30–150 m) have recently received increased attention as a potential source of larvae (e.g., the refugia hypothesis) to repopulate a select subset of the shallow water (<30 m) coral fauna. To test the refugia hypothesis we used highly polymorphic Amplified Fragment Length Polymorphism (AFLP) markers as a means to assess small-scale genetic heterogeneity between geographic locations and across depth clines in the Caribbean coral, Montastraea cavernosa. Zooxanthellae-free DNA extracts of coral samples (N = 105) were analyzed from four depths, shallow (3–10 m), medium (15–25 m), deep (30–50 m) and very deep (60–90 m) from Little Cayman Island (LCI), Lee Stocking Island (LSI), Bahamas and San Salvador (SS), Bahamas which range in distance from 170 to 1,600 km apart. Using AMOVA analysis there were significant differences in ΦST values in pair wise comparisons between LCI and LSI. Among depths at LCI, there was significant genetic differentiation between shallow and medium versus deep and very deep depths in contrast there were no significant differences in ΦST values among depths at LSI. The assignment program AFLPOP, however, correctly assigned 95.7% of the LCI and LSI samples to the depths from which they were collected, differentiating among populations as little as 10 to 20 m in depth from one another. Discriminant function analysis of the data showed significant differentiation among samples when categorized by collection site as well as collection depth. FST outlier analyses identified 2 loci under positive selection and 3 under balancing selection at LCI. At LSI 2 loci were identified, both showing balancing selection. This data shows that adult populations of M. cavernosa separated by depths of tens of meters exhibits significant genetic structure, indicative of low population connectivity among and within sites and are not supplying successful recruits to adjacent coral reefs less than 30 m in depth.