Factors affecting the allocation of paternal care in waterbugs (Belostoma flumineum Say)

Summary Male giant waterbugs (Belostoma flumineum Say) brood eggs oviposited on their dorsa by conspecific females. Laboratory observations indicate that viable egg pads are occasionally discarded before hatching. Theory predicts that such behavior should occur only if the costs incurred by brooding exceed the benefits of hatching the egg pad. We studied the effects of egg pad size, time invested in brooding, and egg viability upon the continuation of paternal care in the giant waterbug. We found that smaller egg pads are less likely to hatch than larger ones, and males appear to be less likely to discard egg pads as temporal investment increases. However, the inviability of eggs did not appear to affect the probability of an egg pad being discarded. Males of this species appear to have evolved a decision-making process involving the continuation of paternal care. Offprint requests to: K.C. Kruse     

Discharge of oilfield-produced water in nueces bay,texas: A case study

During oil and gas production, water is often extracted from geological formations along with the hydrocarbons. These "produced waters" have been discharged to Nueces Bay since the turn of the century. These effluents were found to be highly toxic, and sediments in the vicinity of the discharges were also toxic. We developed a map of wells and produced-water discharge sites in the vicinity of Nueces Bay and identified numerous unplugged wells suitable for conversion to produced water disposal wells. An economic analysis of conversion to subterranean injection of produced water indicates that most of the wells currently in production could pay out the cost of conversion to injection in one to three years. The use of one injection well for two or more water-producing wells could yield greater savings. Wells that could not support the cost of injection are small producers, and their loss would not constitute a major loss of jobs or dollars to the area. This study could serve as a useful model for evaluating the economic feasibility of conversion to injection in other areas of Texas and Louisiana.     

Climate change adaptation in the ski industry

Regardless of the success of climate change mitigation efforts, the international community has concluded that societies around the world will need to adapt to some magnitude of climate change in the 21st century. While some economic sectors (e.g., agriculture, water resources and construction) have been actively engaged in climate change adaptation research for years, adaptation has received scant consideration within the tourism-recreation industry. This is particularly the case for adaptation by tourism operators (supply-side). One exception where progress on supply-side climate adaptation has been made is the ski industry. This paper provides a brief overview of the literature on the implications of climate change for the international ski industry and how adaptation by ski area operators has been treated within these studies. This is followed by an inventory of climate adaptation practices currently used by ski industry stakeholders, including the historical development of certain key adaptations and constraints to wider use. The characteristics of ski areas with higher adaptive capacity are identified. Considering the highly competitive nature of the ski industry and the generally low climate change risk appraisal within the industry, climate change adaptation is anticipated to remain individualistic and reactive for some time. With only a few exceptions, the existing climate change literature on winter tourism has not considered the wide range of adaptation options identified in this paper and has likely overestimated potential damages. An important task for future studies is to develop methodologies to incorporate adaptation so that a more accurate understanding of the vulnerability of the international ski industry can be ascertained.     

Inferring Threat from Scientific Collections

Exact formulas for the probability of extinction or change in the conservation status of species are described for data based on frequency of sighting. These formulas generalize an expression previously described for the probability of extinction from (binary) sighting data. The formulas will be used in contexts where sightings are recorded as frequencies, such as when observations are aggregated in time. We argue that computing the probability of extinction or change in conservation status will be most useful for setting conservation priorities and in screening large data sets contained in museum and herbarium collections and in biological resource inventories.     

Two heavy metal-binding proteins in the midgut gland of the crab Carcinus maenas

Two heavy metal-binding proteins occur naturally in the midgut glands of Carcinus maenas (L.) collected from the Firth of Clyde, Scotland. These proteins, of approximately 27,000 and 11,500 MW (molecular weight) have previously been described as Cd-binding proteins after their induction by high concentrations of cadmium in the laboratory. The 27,000 MW heavy metal-binding protein is bound to about 0.10 g-at of Cd, 0.70 g-at of Zn and 0.31 g-at of Cu per mole of protein; 7.7, 7.9 and 1.1%, respectively, of the soluble Cd, Zn and Cu in the midgut gland are associated with this 27,000 MW protein (6.7, 1.6 and 0.9% of the total midgut gland Cd, Zn and Cu). The 11,500 MW protein is bound to about 0.04 g-at of Cd, 0.37 g-at of Zn and 1.54 g-at of Cu per mole of protein; 29.3, 31.3 and 41.7%, respectively, of the soluble Cd, Zn and Cu in the midgut gland are associated with this protein (25.7, 6.3 and 34.4% of the total midgut gland Cd, Zn and Cu). Neither heavy metal-binding protein is bound to measurable amounts of lead.     

Population differences in nerve resistance to paralytic shellfish toxins in softshell clam, <Emphasis Type="Italic">Mya arenaria</Emphasis>, associated with sodium channel mutations

The softshell clam, Mya arenaria, is a commercially important bivalve with wide latitudinal distribution in North America. Populations of clams with a history of repeated exposure to toxic Alexandrium spp. have developed a natural resistance to the paralytic shellfish toxins (PSTs) produced by these algae. An association between PST resistance in individual clams and a single mutation in the saxitoxin (STX) binding region of the α-subunit of the voltage-gated sodium (Na⁺) channel gene was previously identified. Here we establish that more than one mutation associated with nerve resistance to STX occurred at this locus. Both cDNA from mRNA and genomic DNA sequences from individual clams are identical demonstrating that both alleles are expressed simultaneously. In addition, one resistant allele per individual is sufficient to confer neural resistance to STX even though heterozygous individuals show an intermediate level of resistance to STX in in vitro nerve trunk assays.     

Algal succession in a Macrocystis pyrifera forest

Algal succession within a subtidal forest of the giant kelp Macrocystis pyrifera was studied by following colonization and community development on concrete blocks fastened to the bottom. Sets of blocks were placed in the bed at 3-month intervals. Subsequent algal development on each set was followed for over a year. All macroscopic species attached to the substrata were noted, and the number and lenght of basal branches determined every 1 to 3 months. Colonizing plants fell into 3 categories: rapid-growing ephemerals, and rapid and slow-growing perennials. Ephemerals such as Giffordia (Ectocarpus) mitchellae, Colpomenia peregrina, and diatom films generally produced and initial bloom on the blocks but were gradually replaced by perennials (articulated corallines, Rhodymenia spp., Gigartina spp.) characteristic of the mature kelp community. These stages, rather than representing “ecological” succession, seemed to reflect differences in growth rate and success in interspecific competition for space and light. Colonization on the blocks varied with season, indicating that most species have either a spring-summer or fall-winter period of maximum reproduction. M. pyrifera sporophyte colonization was greatest in spring. During community development, algal diversity (H), number of species (s) and evenness (J) all reached a peak within 100 to 200 days regardless of the time the blocks were started. Diversity and number of species then fell as ephemeral species disappeared. These species were apparently unable to compete with perennials and, once gone, did not recolonize. Evenness remained high.     

Reproductive effects of tris(4-chlorophenyl)methanol in the rat.

Tris(4-chlorophenyl)methanol (TCPM) is a global contaminant of unknown origin that is structurally related to the endocrine modulating pesticides 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and Dicofol. Therefore, the potential reproductive toxic effects of TCPM were investigated in sexually mature male Sprague Dawley rats (n = 20) treated with 1.0, 10.0 or 100 ppm of TCPM mixed in the diet for 28 days. The calculated TCPM intake was 0.0, 0.1, 1.2 and 12.4 mg/kg/day, respectively. Serum concentrations of follicle stimulating hormone (FSH) in terminal blood samples were significantly (P < 0.02) elevated in the highest dose group compared to the controls. In contrast, dietary exposure to TCPM had no effect on circulating levels of luteinizing hormone (LH), testosterone (T) and the T/LH ratio. Incubation of MCF-7 cells with increasing concentrations of TCPM failed to either induce proliferation or to block the proliferative effect induced by estradiol indicating that TCPM is neither estrogenic or anti-estrogenic. Relative binding affinity studies using androgen receptors from the prostate revealed that TCPM has a binding affinity comparable to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), the principle metabolite of DDT. In addition, the calculated Ki (0.62 microM) for TCPM is lower than the reported Ki's for the antiandrogenic pesticides p,p'-DDE and vinclozolin. Although TCPM binds with the androgen receptor in vitro, the absence of both an effect on serum T levels and morphological changes in the testis suggests that the mechanism of action for elevated FSH levels seen in vivo may not involve an antiandrogenic effect of TCPM at the dose level used in this study. The no adverse effect level for reproductive effects of TCPM is 10 ppm which is equivalent to a calculated intake of 1.2 mg/kg/day.     

Measurement of 13C/12C of chloroacetic acids by gas chromatography/combustion/isotope ratio mass spectrometry

This paper describes a novel analytical methodology using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to measure the 13C/12C ratios of chloroacetic acids (CAAs). CAAs are a major class of environmental pollutants that are widely distributed throughout the world, often at relatively high concentrations, and are of concern due to their toxic effects, particularly on plants. The 13C/12C of CAA reagents was measured by IRMS subsequent to offline combustion. Aqueous solutions of these CAAs were derivatized to the corresponding methyl chloroacetates (MCAAs) with acidic methanol with a known isotopic composition, extracted into pentane, and analyzed by GC/C/IRMS. Measured 13C/12C ratios of derivatized MCAAs were in agreement with calculated values within 1 per thousand for monochloroacetic acid and trichloroacetic acid and within 2 per thousand for dichloroacetic acid, suggesting that methylation and other analytical methodology steps do not isotopically fractionate derivatized MCAAs. 13C/12C ratios of reagent CAAs from different sources had varying isotopic signatures suggesting differences in source carbon and/or production methods. Our results underscore the potential of stable isotopes to serve as tracers of environmental sources of CAAs.