Robert A. Angus

Triclosan has endocrine-disrupting effects in male western mosquitofish, Gambusia affinis.

Triclosan (TCS) is an antibacterial agent used in a variety of personal care and industrial products. Triclosan and its environmentally transformed derivative, methyl-TCS, have been detected in waters receiving effluent from public wastewater treatment plants. Previous studies have demonstrated that TCS has the potential to act as an endocrine disruptor. The present study tested the hypothesis that TCS acts as an endocrine-disrupting agent in fish. Mature male western mosquitofish, Gambusia affinis, were exposed to TCS concentrations of 100, 200, and 350 nM (29.0, 57.9, and 101.3 microg/L) for 35 d by the static renewal method. Induction of the normally female-limited vitellogenin gene expression and reduction in sperm count were quantified as biomarkers of endocrine disruption. Vitellogenin mRNA expression was significantly elevated in the 350 nM TCS treatment. Sperm counts in the same treatment group were significantly decreased. The mean hepatosomatic index in the 350 nM treatment group was significantly increased. This study demonstrates that TCS has the potential to act as an endocrine disruptor in male mosquitofish.

Rapid dissolution of shells of weakly calcified Antarctic benthic macroorganisms indicates high vulnerability to ocean acidification.

Abstract Antarctic calcified macroorganisms are particularly vulnerable to ocean acidification because many are weakly calcified, the dissolution rates of calcium carbonate are inversely related to temperature, and high latitude seas are predicted to become undersaturated in aragonite by the year 2100. We examined the post-mortem dissolution rates of aragonitic and calcitic shells from four species of Antarctic benthic marine invertebrates (two bivalves, one limpet, one brachiopod) and the thallus of a limpet shell-encrusting coralline alga exposed to acidified pH (7.4) or non-acidified pH (8.2) seawater at a constant temperature of 4°C. Within a period of only 14–35 days, shells of all four species held in pH 7.4 seawater had suffered significant dissolution. Despite calcite being 35% less soluble in seawater than aragonite, there was surprisingly, no consistent pattern of calcitic shells having slower dissolution rates than aragonitic shells. Outer surfaces of shells held in pH 7.4 seawater exhibited deterioration by day 35, and by day 56 there was exposure of aragonitic or calcitic prisms within the shell architecture of three of the macroinvertebrate species. Dissolution of coralline algae was confirmed by differences in weight loss in limpet shells with and without coralline algae. By day 56, thalli of the coralline alga held in pH 7.4 displayed a loss of definition of the conceptacle pores and cracking was evident at the zone of interface with limpet shells. Experimental studies are needed to evaluate whether there are adequate compensatory mechanisms in these and other calcified Antarctic benthic macroorganisms to cope with anticipated ocean acidification. In their absence, these organisms, and the communities they comprise, are likely to be among the first to experience the cascading impacts of ocean acidification.

Production of Androgens by Microbial Transformation of Progesterone in Vitro: A Model for Androgen Production in Rivers Receiving Paper Mill Effluent

We have previously documented the presence of progesterone and androstenedione in the water column and bottom sediments of the Fenholloway River, Taylor County, Florida. This river receives paper mill effluent and contains masculinized female mosquitofish. We hypothesized that plant sterols (e.g., β-sitosterol) derived from the pulping of pine trees are transformed by bacteria into progesterone and subsequently into 17α-hydroxyprogesterone, androstenedione, and other androgens. In this study, we demonstrate that these same androgens can be produced in vitro from the bacterium Mycobacterium smegmatis. In a second part to this study, we reextracted and reanalyzed the sediment from the Fenholloway River and verified the presence of androstadienedione, a Δ1 steroid with androgen activity.

The Mg-Calcite Composition of Antarctic Echinoderms: Important Implications for Predicting the Impacts of Ocean Acidification

The Southern Ocean is considered to be the canary in the coal mine with respect to the first effects of ocean acidification (OA). This vulnerability is due to naturally low carbonate ion concentrations that result from the effect of low temperature on acid-base dissociation coefficients, from the high solubility of CO2 at low temperature, and from ocean mixing. Consequently, the two calcium carbonate polymorphs, aragonite and calcite, are expected to become undersaturated in the Southern Ocean within 50 and 100 years, respectively. Marine invertebrates such as echinoderms, whose skeletons are classified as high-magnesium carbonate (>4% mol MgCO3), are even more vulnerable to OA than organisms whose skeletons consist primarily of aragonite or calcite, with respect to both increased susceptibility to skeletal dissolution and further challenge to their production of skeletal elements. Currently, despite their critical importance to predicting the effects of OA, there is almost no information on the Mg-calcite composition of Antarctic echinoderms, a group known to be a major contributor to the global marine carbon cycle. Here we report the Mg-calcite compositions of 26 species of Antarctic echinoderms, representing four classes. As seen in tropical and temperate echinoderms, Mg-calcite levels varied with taxonomic class, with sea stars generally having the highest levels. When combined with published data for echinoderms from primarily temperate and tropical latitudes, our findings support the hypothesis that Mg-calcite level varies inversely with latitude. Sea stars and brittle stars, key players in Antarctic benthic communities, are likely to be the first echinoderms to be challenged by near-term OA.

Historical Changes in the Ichthyofaunal Assemblages of the Upper Cahaba River in Alabama Associated with Extensive Urban Development in the Watershed

ABSTRACT The upper Cahaba River in Alabama has experienced extensive urban development in its watershed in recent years. To assess the effects that these developments have had on the ichthyofauna, we compared data from samples made at 12 stations by other researchers prior to 1984 to data from samples collected by us at the same sites between 1995–97. Historical collections produced a total of 44 species, whereas recent samples produced 42. Two species, the blue shiner (Cyprinella caerulea) and the Alabama shad (Alosa alabamae), have been extirpated from this system. Relative abundances of the various taxa in recent samples correlated poorly with those of historical samples, indicating that the compositions of the ichthyological communities have changed. Disturbance-tolerant cyprinids (minnows) have generally increased in percent relative abundance (PRA) in recent collections, whereas the disturbance-sensitive cyprinids have generally decreased. The PRA of percids (darters) has decreased in recent collections, especially the disturbance-sensitive species such as the coal darter (Percina brevicauda) and the greenbreast darter (Etheostoma jordani). The ichthyofaunal diversity, as measured by several indices, has decreased in recent samples. These changes in the fish populations have occurred concurrently with extensive urbanization and resultant degradation of water and habitat that has taken place in the watershed over the last 20 years.

An evaluation of sponge-associated amphipods from the Antarctic Peninsula

Abstract Nearshore marine benthic algal communities along the western Antarctic Peninsula harbour extremely high densities of amphipods that probably play important roles in nutrient and energy flow. This study extends our evaluation of the importance of amphipods in the nearshore Antarctic Peninsular benthic communities and focuses on sponge associations. We found a mean density of 542 amphipods per litre (L) sponge for twelve species of ecologically dominant sponges. The highest mean density (1295 amphipods per L sponge) occurred with Dendrilla membranosa Pallas. The amphipod community associated with the 12 sponges was diverse (38 species), with mean species richness values ranging from two to eight species. Mean Shannon diversity indices (H’) ranged from 0.52 to 1.49. Amphipods did not appear to have obligate host relationships. Qualitative gut content analyses indicated that 12 of the 38 amphipod species were found with sponge spicules in their guts. However, only one of the amphipods, Echiniphimedia hodgsoni Walker, had considerable amounts of spicules in the gut. Organic lipophilic and hydrophilic extracts of the twelve sponges were presented in alginate food disks to a sympatric omnivorous amphipod in feeding bioassays and extracts of only two sponges deterred feeding.

The use of feather meal as a replacement for fish meal in the diet of Oreochromis niloticus fry

Abstract Four diets were developed in which equal weights of hydrolyzed feather meal (F) replaced equal weights of fish and meat and bone (FMB) meal in the following percentages: 0/100, 33/66, 66/33 and 100/0 (F/FMB). Each diet was proffered ab libitum to two replicate groups of 60 fry (mean wet weight 12·3 ± 0·3 mg) for 42 days. Survival was not significantly different among treatments (> 93%). The individuals fed 0/100, 33/66 and 66/33 (F/FMB) did not differ significantly in median or mean weight gain, however, individuals fed 100/0 (F/FMB) were significantly smaller than those fed all other diets at days 21 and 42. The growth of Oreochromis niloticus fry was not compromised by replacement of up to 66% of fish meal and meat and bone meal (9·9% of the total diet) with feather meal. Feeding feather meal as a sole source of animal protein, however, appears to result in a decrease in weight gain and associated growth parameters.

Mosquitofish (Gambusia affinis) vitellogenin: identification, purification, and immunoassay

Vitellogenin is a phospholipoglycoprotein precursor of egg yolk. In mature female fish, vitellogenin is synthesized and secreted by the liver in response to circulating estrogens. Vitellogenin is normally undetectable in the blood of male fish, but can be induced by exposure to compounds possessing estrogenic activity. Thus, the presence of vitellogenin in blood of male fish can serve as a useful biomarker for assessing previous exposure to estrogenic compounds. In the present study, we report identification and purification of vitellogenin in the mosquitofish (Gambusia affinis). Anti-vitellogenin immune serum was generated and used to develop an immunoblot assay for detection of vitellogenin. A combination of immunoblotting and densitometric scanning was used to assess the time- and dose-dependent effects of 17alpha-ethynylestradiol on vitellogenesis in male G. affinis. The results indicate that changes in the level of vitellogenin in mosquitofish blood can be reliably detected by the immunoblot assay, and that the mosquitofish may be a useful bioindicator organism for detecting estrogenic contamination of the aquatic environment.

Comparison of a Small-Mesh Seine and a Backpack Electroshocker for Evaluating Fish Populations in a North-Central Alabama Stream

Abstract A comparison of the sampling effectiveness of a backpack electroshocker and small-mesh seine was conducted on the upper Cahaba River in the Valley and Ridge physiographic province of north-central Alabama. Each of 15 sites was sampled once during fall 1995 (20 September–23 October), spring 1996 (2 May–20 June), and fall 1996 (20 September–16 October). Sampling was conducted with both gears on the same day, and the same amount of sampling time was allocated to each gear. Samples were segregated into seven groups (Cyprinidae, Catostomidae, Percidae, Centrarchidae [further subdivided into sunfish-crappie and bass categories], and other families as a group), and comparisons of the percent relative abundance (PRA) of groups were made between gears at each sampling station. The PRAs of the groups differed significantly between gears at all 15 stations. Cyprinid PRAs were consistently higher in seine collections, whereas percids, sunfish-crappie, and bass PRAs were higher in electroshocker collections. ...

Phenol Tolerance in Populations of Mosquitofish from Polluted and Nonpolluted Waters

Abstract The phenol tolerances of three Alabama populations of mosquitofish Gambusia affinis were compared; two populations lived in industrially polluted streams and one in a nonpolluted lake. In 48-hour static tests, the median lethal concentration (LC50) of phenol was significantly higher for mosquitofish from a stream that received coke-treatment wastewater from a steel plant than for the other two populations. Especially at low phenol concentrations, most mortality occurred during the first few hours of exposure, indicating that some individuals were much more susceptible to phenol than others. Eight-hour assays of fish from the lake and the most polluted stream confirmed the presence of distinctly phenol-resistant and phenol-susceptible groups of fish. The differences in LC50 values for these two populations reflect differing proportions of resistant individuals. Resistant fish made up 67–80% of the polluted-stream population with the high LC50 and only 23–27% of the nonpolluted-lake population. Rep...