ALBERT

Description: Modern models for the development and evolution of the geochemical heterogeneity in the Earth's mantle and the genesis of mantle magmas attach much importance to the processes of interaction between deepseated rocks and metasomatic fluids, which are able, when occurring under mantle conditions, to dissolve significant amounts of major and trace elements (see, for example, [1]). Fluorine is one of the major anions of natural fluids and also one of the principal complex-forming ligands of several metals. To evaluate the possible role of fluorine in the processes of mantle magma genesis and to identify the source of this element in natural magmas in various geodynamic environments, it is necessary to know the fluorine concentration in primitive mantle melts. These data are still relatively scarce, particularly for low alkaline magmas [2-4]. The fluorine concentrations in magmas from suprasubduction zones, whose genesis is largely controlled by the interaction between mantle rocks and fluids, remain poorly known and need further refinement. Data presented in this paper are among the first to characterize the concentrations of fluorine in primitive magmas of suprasubduction zones. These data were obtained by secondary ion mass spectrometry of chill glasses from the lava complex of the Troodos ophiolites in Cyprus. Along with information on the concentrations of major and trace elements, H2O, and Cl in the glasses, our results make it possible to utilize the example of the Troodos ophiolites to characterize the main regularities in the geochemistry of fluorine during the origin of magmas above subduction zones and to assay the contributions of various components that participated in the processes of mantle melting. These data are among the first to demonstrate that subduction-related melts became enriched in F relative to LREE.

Description: Eggs of the southern calamary Sepioteuthis australis were sampled from spawning sites off eastern Tasmania, Australia, during an austral spring/summer spawning season. At fortnightly intervals, 3 unfouled and 3 biofouled egg strands were sampled from 6 to 23 distinct egg masses (Neggs = 2649). Highly significant variation was noted between sample dates in the frequency of unfertilised eggs, developmental abnormalities and egg mortalities. Unfertilised eggs were only found during late October and early November and represented a mean 2.12 ± 1.25% SE and 0.58 ± 0.58% SE eggs per strand respectively. Frequency of abnormality varied significantly between sample dates and ranged from 8.35 ± 1.86% SE eggs per strand in late November to 0.92 ± 0.41% SE in late December. Abnormalities were arbitrarily categorised as defects in external yolk sac morphology, reduced embryonic size, mantle deformities, eye deformities and arm deformities. Defects in external yolk sac morphology were found throughout the spawning season and accounted for 46.3% of all abnormalities. Incidence of mortality varied significantly between sample dates and ranged from 1.40 ± 0.68% SE per strand in late October to 11.61 ± 3.23% SE in early January. Highly significant correlation was noted between incidence of developmental abnormality and within-strand egg position. Biofouled egg strands were characterised by comparatively low incidences of unfertilised and dead eggs. The influences of environment, egg position and biofouling upon embryonic development in S. australis are discussed.

Description: Bioaccumulation of 65Zn and 109Cd by the cuttlefish Sepia officinalis L. was studied at different stages of its life cycle, i.e. in embryos, juveniles and adults, following exposures via sea water, sediments and food. Cuttlefish eggs efficiently accumulated both elements from seawater with bioconcentration factors of 79 for 65Zn and 46 for 109Cd after 11 d exposure. Most of the radiotracers were found in the capsule membrane of the eggs, demonstrating that the capsule acts as a shield to protect embryos against metals. Juveniles and adults efficiently bioconcentrated both radiotracers from seawater, with the muscular tissues containing 84% of the total 65Zn and 62% of the total 109Cd. Loss kinetics followed a single exponential function for 65Zn, while for 109Cd loss was best described by a double exponential model. Biological half-lives for elimination were ca. 2 mo for both elements. After 29 d depuration in uncontaminated seawater, 76 to 87% of the radiotracers were found in the digestive gland. For both elements, the dissolved phase can be considered as a significant source of accumulation. In an experiment with radiolabelled sediments, transfer factors were very low, even after 29 d exposure. Food-chain transfer experiments demonstrated that both juveniles and adults assimilated 65Zn and 109Cd very efficiently. Moreover, loss of ingested radiotracers was much slower than elimination of 65Zn and 109Cd taken up from seawater, indicating a very strong retention of dietary Cd and Zn by juvenile as well as by adult cuttlefish. As with direct uptake from seawater, ingested radiotracers were mainly found in the digestive gland, with fractions reaching 82% for 65Zn and 97% for 109Cd after 29 d depuration. These tracer experiments indicate that (1) food is the likely primary pathway for Zn and Cd bioaccumulation in S. officinalis, and (2) the digestive gland plays a major role in the subsequent storage and presumed detoxification of these elements regardless of the uptake pathway.

Description: This study investigated the pattern and scale of distribution, movements and range use of the northern bottlenose whale Hyperoodon ampullatus above a submarine canyon, the Gully, off eastern Canada between 1988 and 1998. Locations and individual identification photographs were collected during encounters with whales. Whales showed a discrete distribution within the canyon associated with water depth (500 to 1500 m) and relatively steep topography. Encounter rate and distribution showed some variation between years. Changes in distribution were observed toward the north or south of the canyon, probably a consequence of changes in prey distribution. Individual whales within the canyon displaced 4 to 5 km over 24 h, with negligible further increase in displacement over time scales up to 20 d (their approximate residency period). Short-term VHF radio-tracking of 5 individuals provided an independent source of movement data, showing displacements of approximately 2 km in 1 h and 5 to 10 km in 1 d. The relative lack of movement observed for these whales supports the hypothesis that the canyon contains a profitable and localized food source. Movements of whales best fit a model of short-term residence within ranges of approximately 25 km2, although the range size of mature males was smaller than that of females and immature males. Photo-resightings were also used to investigate variation in the positions of individual whales within the Gully. Within years, individuals showed some separation of ranges associated with periods of high whale abundance, but there was no separation between different age-sex classes. Between years, mature males showed consistent spatial orientations relative to each other, suggesting preferred locations possibly related to mating opportunities.

Description: We used stable-isotope analysis (SIA) to evaluate sources of variation in the diet of and prey selection by Magellanic penguins Spheniscus magellanicus breeding on the Argentinean Patagonia coast. Our aim was to determine potential sources of variation in diet, focusing mainly on sex and age, although geographic and temporal effects were also taken into account. In addition, we evaluated how prey selection affects offspring quality. We measured stable nitrogen ( δ15N) and carbon (δ13C) isotope values in whole blood of chicks (n = 98), yearlings (n = 15) and adults (n = 143) in 9 different breeding colonies during 2 consecutive breeding seasons (1999 and 2000). We also measured stable isotope values in representative prey consumed by this species. Stable nitrogen and carbon isotope values in blood for penguins varied from 17.8 to 20.0” and from -18.1 to -14.8”, respectively. Both colony and season had a significant effect on the 2 isotope signatures. Adult males had higher blood δ15N and δ13C values than females. Age significantly affected both δ15N and δ13C values, with chicks showing the highest and yearlings the lowest δ15N values. Chicks showed lower δ13C values than yearlings and adults. Mean prey δ15N values ranged from 13.6 ” in squid to 18.0 ” in octopus. As anchovy, the main prey consumed by the species in the study area, did not differ from other fish species (hake) in its δ15N value, we used it to represent a fish dietary alternative. Using a 2 source (anchovy and squid) isotopic mixing model, we determined that the mean proportion of anchovy in the diet was 49% for yearlings, 76% for chicks, and 69% and 67% for adult males and females, respectively. Sex and age differences in diet, as revealed by stable isotopes, may be the consequence of individual morphology (sexual size dimorphism) and reproductive constraints imposed by chick development since growing young require more nutritive prey than adults and yearlings. This reasoning would also explain the significant and positive correlation found between proportion of anchovy in the diet and body condition of chicks.

Description: This study describes the incidence of embryonic mortality and differential development in southern calamary Sepioteuthis australis eggs. Late-stage S. australis egg strands harbouring multiple embryos close to hatching were sampled from shallow (〈4 m) Tasmanian spawning grounds from early November 2000 to January 2001. Sepioteuthis australis embryos were found to develop asynchronously within individual egg strands with proximal embryos developing slower and suffering higher mortality than their distal siblings. The magnitude of asynchrony, however, differed throughout the season with greater within-strand differences observed when embryos were exposed to broader incubation temperatures. Unexpectedly, embryos developed more synchronously within biologically fouled strands and displayed a significantly lower incidence of mortality compared to those developing in unfouled strands. Embryonic mortality was initially low (4%) and significantly increased to 20% in late November, remaining above 10% until late December. This dramatic increase in mortality was not strongly associated with increasing water temperatures, but coincided with a period of heavy rainfall alluding to potential salinity effects.

Description: The majority of cephalopods are thought to have limitations arising from physiology and locomotion that exclude them from shallow, highly variable, euryhaline environments. The brief squid Lolliguncula brevis may be a notable exception because it tolerates low salinities, withstands a wide range of environmental conditions, and swims readily in shallow water. Little is known about the distribution of L. brevis in Chesapeake Bay, a diverse and highly variable estuary. Therefore, a survey of L. brevis was conducted in the Virginia portion of Chesapeake Bay from 1993 to 1997 using a 9.1 m otter trawl, and the effects of selected factors on squid presence were assessed using logistic regression analysis. During spring through fall, L. brevis was collected over a wide range of bottom-water salinities (17.9 to 35.0 ‰), bottom-water temperatures (8.1 to 29.6°C), bottom-water dissolved oxygen levels (1.9 to 14.6 mg O2 l-1), and depths (1.8 to 29. but it was not present in trawls conducted during winter in. L. brevis, especially juveniles 〈 60 mm dorsal mantle length (DML), were abundant, frequently ranking in the upper 12% of overall annual nektonic trawl catches, and during the fall of some years, ranking second to anchovies. The probability of catching a squid increased in Chesapeake Bay at higher salinities and water temperatures, and was much greater in normoxic than in hypoxic waters; these variables had a profound influence on both annual and seasonal variability in distribution. Salinity had the largest influence on squid distribution, with squid being completely absent from the bay when salinity was 〈17.9” and most abundant in the fall when salinity was highest (despite declines in water temperature). Squid were most prevalent at depths between 10 and 15 m. The results of this study suggest that L. brevis is an important component of the Chesapeake Bay ecosystem when salinities and water temperatures are within tolerance limits and that unlike other squids, L. brevis may be well-equipped for an inshore, euryhaline existence.