ALBERT

Description: The ability of populations to adapt to environmental change and the spatial scale at which this adaptation occurs are fundamentally important issues in evolutionary biology, and ones that may benefit greatly from the study of genetic variability in reaction norms, which represent the plasticity of phenotypic traits across an environmental gradient. Therefore variable reaction norms can reflect genetic differences in the ability of individuals, families, populations, and species to respond to natural and anthropogenic environmental change. Fishes are ideal organisms in which to study plasticity because of their remarkable intraspecific morphological, physiological, behavioural, and life history variation. Here, we review studies demonstrating genetic variability in reaction norms in fishes. Genetic variability in plasticity among full- and half-sib families suggests potential for some populations to develop an adaptive norm of reaction (recalling that plasticity need not be adaptive). Reaction norm variability among populations suggests that adaptive genetic divergence can occur rapidly when selection pressures are strong and that the spatial scale of adaptation is much smaller than previously believed for some species with high dispersal capabilities. These studies demonstrate the potential of using reaction norms to study the evolution of novel phenotypes and the influence of temporal environmental variability and gene flow on the evolution of phenotypic plasticity, which can then be used to predict how populations will respond to directional environmental change. To promote future research into genetic variability in reaction norms, we propose questions that would benefit from such an approach and discuss some important considerations for designing experiments to investigate questions related to genetic variation in plasticity and phenotypic evolution.

Description: The fate of chromium (Cr) – a redox sensitive metal – in surface sediments is closely linked to early diagenetic processes. This review summarizes the main redox pathways that have been clearly identified over recent decades concerning the behavior of Cr(III,VI) in aquatic environments, and applies them to surface sediments where data for redox speciation remain limited. Overall, abiotic redox reactions that govern the speciation of Cr involve manganese (Mn) (III,IV) (hydr)-oxydes for Cr(III) oxidation, Cr(VI)-reducing species (dissolved iron (Fe) (II) and hydrosulfide (HS)−), and Cr(VI)-reducing phases (ferrous and sulfide minerals, as well as Fe(II)-bearing minerals). Bacterial activity is also responsible for the redox interconversion between Cr(III) and Cr(VI): biotic reduction of Cr(VI) to Cr(III) is observed through either detoxification or dissimilatory reduction. Whereas Mn(II)-oxidizing bacteria are known to promote indirect oxidation of Cr(III) to Cr(VI), the reaction mechanisms are unresolved. Conversely, oxygen (O2), nitrate (NO3−), and nitrite (NO2−) do not appear to play any role in Cr(III) oxidation. Additionally, Mn(II) and ammonium (NH4+) are not known to promote Cr(VI) reduction. Once reduced, the mobility of Cr(III) in sediments is significantly restricted and regulated by precipitation and sorption processes. Finally, even if the role of natural organic matter in sediment has been determined, further research is required to identify the complexation mechanisms.

Description: Velvet shell, Velutina velutina (O. F. Müller, 1776), is a specialist predator of ascidians, like other members of the gastropod family Velutinidae. Globally, invasive ascidians have become problematic, ecologically and economically, yet ecological knowledge of velutinids remains limited. This study outlines the life history and feeding ecology of V. velutina in eastern Canada based on laboratory work complemented by field observations. The life history of V. velutina is closely linked with ascidians, which serve as prey and protection for their egg capsules. Egg capsules were embedded within tunics of Aplidium glabrum (Verrill, 1871) and Ascidia callosa Stimpson, 1852, but the latter was preferred. Seasonal behavioural shifts were consistent annually and corresponded with seawater temperature cycles. Feeding dominated during the coldest months (January – May), growth occurred as water temperature increased to the annual maximum (June and July), transitioned to mating during the warmest period (July/August), and egg capsule deposition dominated as water temperature declined (November – January). Larvae hatched between January and July after 2 – 4 months of development. Velvet shell preyed on all ascidian species presented during this study, including golden star tunicate, Botryllus schlosseri (Pallas, 1766), and vase tunicate, Ciona intestinalis (Linnaeus, 1767), two non-indigenous species, although solitary species were preferred.

Description: There was no difference in weight between diploid and triploid landlocked Atlantic salmon (Salmo saiar) measured over a 9-mo period, but triploids were consistently longer (FL) and thus had a lower condition factor than diploids. The gonadosomatic index (GSI) of triploid females was only 7.7% that of diploid females, while the GSI of triploid males was 52% that of diploid males. Triploid ovaries had the external appearance of undeveloped gonads, but every triploid female did in fact produce a small number of oocytes (from 1 to 12, versus several hundred oocytes in each diploid female). Triploid testes were well developed but contained few spermatids and no spermatozoa. Diploid testes, on the other hand, were in advanced stages of spermiogenesis. None of the triploid males reached spermiation.

Description: Nodularia Mertens ex Bornet & Flahault originally established in 1822, has had a total of 28 taxa described. It is restricted in distribution primarily to brackish coastal waters and inland lakes and ponds. In British Columbia (Canada) these lakes and ponds have extreme ranges of salinity (4–400‰) and temperature (0–35 °C). Laboratory studies of 16 isolates indicated maximum growth at 5–10‰, salinity (range 1–60‰), 25–30 °C, pH 10.0–10.5 (range 7.0–10.5) at light intensity of 6000 lx. No preference was shown for dominant anions (Na+, Mg2+) or cations (Cl−, CO32−, S42−). Sheath and akinete characteristics were variable, whereas vegetative cell shape, heterocyst location, and akinete formation were more stable. Investigation of field-collected material, laboratory-grown cultures, and study of herbarium specimens indicate that all the described taxa belong to either N. harveyana [Thwaites] Thuret ex Bornet & Flahault 1886 or N. spumigena Mertens ex Bornet & Flahault 1886. The latter is named the syntype and lectotype material is designated.

Description: Although Gram-negative bacterial pathogens continue to impart a substantial burden on global healthcare systems, much remains to be understood about aspects of basic physiology in these organisms. In recent years, cyclic-diguanylate (c-di-GMP) has emerged as a key regulator of a number of important processes related to pathogenicity, including biofilm formation, motility, and virulence. In an effort to discover chemical genetic probes for studying Vibrio cholerae we have developed a new motility-based high-throughput screen to identify compounds that modulate c-di-GMP levels. Using this new screening platform, we tested a library of microbially derived marine natural products extracts, leading to the discovery of the bioactive lipid (S)-sebastenoic acid. The evaluation of the effect of this new compound on bacterial motility, vpsL expression, and biofilm formation implied that (S)-sebastenoic acid may alter phenotypes associated to c-di-GMP signaling in V. cholerae.

Description: Bernard, F. 1981. Canadian west coast flying squid experimental fishery. Can. Ind. Re. Fish. Aquat. Sci. 122: 23p. This report covers the experimental drift net fishery for the flying squid Ommastrephes bartramii (Lesuer) on the high seas off the west coast of Vancouver Island in the summer of 1980. Ctaches were commercial, but development of a fishery is not imminent because of a lack of suitable large vesels and shore-based processing facilities. Further constraints are the large amount of manpower required to run gear and process catch and the volatile prices and deman for squid.

Description: Tue south Caspian subbasin extends from the foot of the Alborz Mountains to the deepest part of Caspian Sea. The Jithological background and tectonic setting of the study area primarily control the deposition ofthick sedimentary sequences of the basin, while hydroclimatic processes exert secondary impacts on the sediment distribution pattern. To evaluate past hydroclimatic changes, short sediment cores were retrieved from the continental shelfand upper slope of the south Caspian Sea and were treated for basic sedimentological properties and mineralogy. Tue results show that the sediments are composed of terrigenous, biogenic, and chemical components. The chemical component has a significant signature in the intemal structure of the sediment, which reflects degradation of organic material due to a succession of aerobic and anaerobic conditions. Aerobic conditions reflect the extreme climatic conditions that Jead to formation of well-oxygenated deep water in lowstands and extremely cold winters, when dense oxygenated water is allowed to touch the bottom sediments. The sediment distribution pattern demonstrates three distinctive areas in the southern continental margin with different organic matter and carbonate content. Pluvial inputs and wave hydrodynamics control the sediment properties and their distribution pattern in the upper shelf, while in deeper parts, the dynamics ofwater stratification and its temporal and Jong·term variations, relating to climate and water Jevel changes, detennine sediment composition. Overall, the sedimentary distribution pattem is a result of their sources in the catchment basin and the hydroclimate of the Caspian Sea.