Continuous Plankton Recorder sampling off the east coast of North America: history and status

The Continuous Plankton Recorder (CPR) survey has sampled plankton on 14 routes off the coasts of the northeast United States and Canada between 1959 and 2000. Six of these routes are still operating and are sampled on a monthly basis. Some 2047 CPR tows have been made to the end of 2000 and the resulting database represents the most extensive time series of marine plankton available anywhere in the northwest Atlantic. The location and time span of coverage of each route is presented. In addition selected information is presented on:

1. zooplankton abundance as departures from baselines for the northeast US continental shelf;

2. interannual variation in seasonality of Gulf of Maine phytoplankton;

3. zooplankton relationships to local hydrography of the Gulf of Maine and to the North Atlantic Oscillation;

4. time-space matrices of zooplankton abundance and anomalies southeast of New York City;

5. time series of phyto- and zooplankton on the Scotian Shelf;

6. seasonal cycles of Phytoplankton Colour and of zooplankton on the Scotian Shelf and Georges Bank, and in the Gulf of Maine; and

7. monthly abundance of zooplankton in Narragansett Bay, Rhode Island.

     

A genetic assessment of the taxonomic status of New Zealand mussels of the genus Xenostrobus Wilson, 1967

ABSTRACT

The genus Xenostrobus consists of small, marine and estuarine mussels that all appear similar externally. One of its estuarine species, Xenostrobus securis, with a native range in New Zealand and Australia, has become invasive in the Northern Hemisphere. No genetic data are available to determine if X. securis populations from the two countries are conspecific. Additionally, marine Xenostrobus from New Zealand have often been regarded as a species, X. neozelanicus, distinct fromthe marine Australian species X. pulex. We combined new DNA sequences with published data to assess the taxonomic status of New Zealand Xenostrobus. The data comprised 658 aligned bases of mitochondrial cytochrome c oxidase subunit I (COI) gene and 331 bases of nuclear histone H3. There was no evidence that X. securis populations from Australia and New Zealand are specifically distinct. Northern Hemisphere specimens of X. securis belonged to Australian, not New Zealand, clades in phylogenetic analyses of COI data, suggesting the former country as their more likely original source. The results confirm that X. neozelanicus and X. pulex are distinct species and for nomenclatural completeness for this taxonomic decision a lectotype is designated for Mytilus ater Zelebor in Dunker and Zelebor, 1866 DunkerW, ZeleborJ. 1866. Bericht über die von der Novara-expedition mitgebrachten Mollusken. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien. 16:909–916. [Google Scholar] [?=?Modiolus neozelanicus Iredale, 1915 IredaleT. 1915. A commentary on Suter’s ‘Manual of New Zealand Mollusca’. Transactions of the New Zealand Institute. 47:417–497. [Google Scholar]].     

Estimating the underwater light field from remote sensing of ocean color

We present a new approach that incorporates two models to estimate the underwater light field from remote sensing of ocean color. The first employs a series of analytical, semi-analytical, and empirical algorithms to retrieve the spectrum of inherent optical properties (IOPs), including the absorption and the backscatter coefficients, from the spectrum of remote sensing reflectance. The second model computes the profile of photosynthetically available radiation E _0,PAR (z) for a vertically homogeneous water column using the information of the retrieved IOPs and the ambient optical environment. This computation is based on an improved look-up table technology that possesses high accuracy, comparable with the full solution of the radiative transfer equation, and meets the computational requirement of remote sensing application. This new approach was validated by in situ measurements and an extensive model-to-model comparison with a wide range of IOPs. We successfully mapped the compensation depth by applying this new approach to process the SeaWiFS imagery. This research suggests that E _0,PAR (z) can be obtained routinely from ocean-color data and may have significant implications for the estimation of global heat and carbon budget.     

Effects of prolonged exposure to 4-tert-octylphenol on toxicity and indices of oestrogenic exposure in the sand goby (Pomatoschistus minutus, Pallas)

Alkylphenolic compounds are present in estuarine and marine environments. They are moderately bioaccumulative, and oestrogenic to fish following three week, in vivo, exposures. The effects of prolonged exposure are, as yet, unclear. Sand goby (Pomatoschistus minutus) were exposed to measured concentrations of 4-tert-octylphenol (OP) in a 28-day, dose-ranging study, and a six month temporal response study. Following 28-days exposure to measured 31+/-6 or 101+/-47 microg l(-1) OP (mean+/-SD), immature male sand goby showed elevated vitellogenin (VTG) mRNA expression. Plasma alkali-labile phosphate concentrations were elevated in both sexes and were higher in females than males. Although measured OP concentrations were variable, they were significantly different for each treatment and a range of concentration-dependent effects were observed. The LC(50) for chronic OP exposure (8 weeks) was 29+/-6 microg l(-1), and both sexes demonstrated concentration and duration dependent increases in VTG mRNA expression. Exposure to 28+/-20 microg l(-1) OP (median+/-95% CI) for 6 months inhibited development of male nuptial colouration and sperm duct glands. These findings are discussed in relation to environmental concentrations of alkylphenols and ecological concerns.     

Methane-dominated thermochemical sulphate reduction in the Triassic Feixianguan Formation East Sichuan Basin, China: towards prediction of fatal H2S concentrations

New sour pools have recently found in the Lower Triassic Feixianguan Fm carbonate reservoirs in the East Sichuan Basin in China with H₂S up to 17.4% by volume. A recent blowout from a well drilled into this formation killed hundreds of people as a result of the percentage concentrations of H₂S. In order to assess the origin of fatal H₂S as well as the cause of petroleum alteration, H₂S concentrations and the isotopes, δ³⁴S and δ¹³C have been collected and measured in gas samples from reservoirs. Anhydrite, pyrite and elemental sulphur δ³⁴S values have been measured for comparison. The high concentrations of H₂S gas are found to occur at depths >3000 m (temperature now at 100 °C) in evaporated platform facies oolitic dolomite or limestone that contains anhydrite nodule occurrence within the reservoirs. Where H₂S concentrations are greater than 10% its δ³⁴S values lie between +12.0 and +13.2‰ CDT. This is within the range of anhydrite δ³⁴S values found within the Feixianguan Fm (+11.0 to +21.7‰; average 15.5±3.5‰ CDT). Thus H₂S must have been generated by thermochemical sulphate reduction (TSR) locally within the reservoirs. Burial history analysis and fluid inclusion data reveal that the temperature at which TSR occurred was greater than about 130–140 °C, suggesting that the present depth-temperature minimum is an artifact of post-TSR uplift. Both methane and ethane were actively involved in TSR since the petroleum became almost totally dry (no alkanes except methane) and methane δ¹³C values become significantly heavier as TSR proceeded. Methane δ¹³C difference thus reflects the extent of TSR. While it is tempting to use a present-day depth control (>3000 m) to predict the distribution of H₂S in the Feixianguan Fm, this is an invalid approach since TSR occurred when the formation was buried some 1000–2000 m deeper than it is at present. The likelihood of differential uplift across the basin means that it is important to develop a basinal understanding of the thermal history of the Feixianguan Fm so that it is possible to determine which parts of the basin have been hotter than 130–140 °C.     

Physical and biological factors influencing the spatial distribution of age-0 walleye pollock (Theragra chalcogramma) around the Pribilof Islands, Bering Sea

The waters around the Pribilof Islands, in the southeast Bering Sea, are a main nursery area for age-0 pollock. Each summer, the islands are surrounded by a well-mixed inshore region, separated from a stratified offshore region by a frontal zone. To study the spatial distribution of age-0 pollock around this frontal structure in relation to physical and biological factors that are likely to influence it, such as advection, age-0 pollock feeding, and predation, samples were collected during September of four consecutive years, 1994–97, along two transects. Samples collected included water column hydrography and currents, acoustic backscatter, and groundfish predator density.Our analysis suggested that different mechanisms may be involved in controlling age-0 pollock distribution north and south of the islands. On the shelf area north of the islands, high age-0 pollock density was significantly associated with areas of high potential for growth only in years or portions of the frontal transect in which predator numbers were relatively low, indicating the importance of predation in controlling fish distribution in this area. In contrast, south of the islands, age-0 pollock distribution was associated more with prey availability, which appeared to be determined by vertical spatial overlap between predators and prey. Moreover, south of the islands, the stronger geostrophic currents, typical of the slope region, were more likely to affect the overall standing biomass of juvenile pollock, by constantly advecting fish away from the area.