Species, tissue and gender-related organochlorine bioaccumulation in white-sided dolphins, pilot whales and their common prey in the northwest Atlantic

Organochlorine concentrations were measured in white-sided dolphins, pilot whales, and their prey from the Gulf of Maine and used to identify species, tissue, and gender differences, and trophic transfer trends, in bioaccumulation. Polychlorinated biphenyl concentrations ([PCB]) in dolphin blubber (13 +/- 7.1 micrograms/g fresh wt.) were twice those in pilot whales, but pesticide concentrations (20 +/- 13 micrograms/g fresh) were similar between species. 4,4'-DDE, trans-non-achlor, Cl6(153) and Cl6(138) concentrations were highest. Skin tissues had more recalcitrant organochlorines than the internal organs. Male dolphins bioaccumulated higher concentrations of nonmetabolizable PCBs and hexachlorocyclohexane (HCH) isomers, whereas pilot whales had no gender-related differences in bioaccumulation. Pilot whales, mackerel, and herring had proportionately higher concentrations of DDTs, whereas [PCB] were higher in dolphins and squid. Although these odontocetes feed at the same trophic level and store a similar suite of contaminants, dolphins bioaccumulated higher and potentially hazardous 4,4'-DDE and PCB concentrations from food in their more geographically restricted range.     

A ternary solid solution model for omphacite and its application to geothermobarometry of eclogites from the Middle Adula nappe (Central Alps, Switzerland)

A ternary solid solution model for omphacite with the end-members jadeite (NaAlSi₂O₆), diopside (CaMgSi₂O₆) and hedenbergite (CaFeSi₂O₆) was derived from experimental data from the literature. The subregular solution model, fitted by linear programming, is best suited to omphacites with very little aegirine component in common eclogites. Applying this solution model to the calculation of equilibrium phase diagrams of eclogites from the Adula nappe (Central Alps, Switzerland) results in large stability fields for common eclogite assemblages (garnet+omphacite+quartz+H₂O±kyanite). Within this field the compositions of garnet and omphacite show very little variation. A precise determination of the peak-pressure and temperature is not possible. The occurrence of amphibole, overgrowing the peak-pressure assemblage in fresh eclogite, suggests retrograde re-equilibration, still under eclogite facies conditions. The computation of isopleths for garnet and pyroxene end-members allows the estimation of the pressure and temperature conditions of this re-equilibration event (19–21  kbar, c .  700 °C).     

High-resolution sediment echosounding off Peru: Late Quaternary depositional sequences and sedimentary structures of a current-dominated shelf

About 6000 km of both bathymetric and high-resolution acoustic profiles were acquired on the shelf and upper slope offshore Peru between 9° S and 14° S. Two new sediment echosounder systems – SEL-96 and SES-2000DS – provided details of the sedimentary structures of the Quaternary sequences within the Sechura-Salaverry, Huacho and Pisco Basins. To a great extent, the poleward undercurrent determines the distribution of sediments. The undercurrent has generated numerous erosional unconformities, it has winnowed hardgrounds and has created mudwaves common between 250 m and 400 m water depth. Distinct subbottom reflectors within sedimentary units represent hiatuses due to periods of intensified winnowing or non-deposition. Erosional unconformities usually marked by pronounced reflectors suggest shifts of the undercurrent system related to climatic changes and eustatic variations of sea level. On a larger scale, the stacked prograding depositional sequences reflect the sea-level cycles of the Middle Pleistocene to the Holocene. Based on the stratigraphy of our piston cores and that of Ocean Drilling Program (ODP) Site 680, the depositional sequences limited by extended unconformities were assigned to oxygen isotope stages 1 to 7. Other sedimentary structures are small straight channels that were conduits for downslope sediment transport. Deformed sediments associated with synsedimentary normal faults result from creep movements indicating beginning slope failure.     

Distribution of nonlinear wave crests

The distribution of nonlinear wave crests is examined on the basis of a theoretical probability density previously given elsewhere (J. Eng. Mech. 120 (1994) 1009). Certain errors contained in the original theoretical density are corrected, and the corresponding exceedance distribution is derived. The resulting theoretical forms of the probability density and exceedance distribution are then slightly simplified and compared with nonlinear wave data gathered under hurricane conditions. The results indicate that the proposed theoretical forms describe the observed distributions of large wave crests better than the Rayleigh law. However, the quantitative accuracy of the predictions is somewhat poor, as is typical of approximate theories based on Gram–Charlier-type expansions.     

Dynamic evolution of the 1997–1999 El Niño–La Niña cycle in the southern California Current System

The development of the strongest El Niño event on record in the equatorial Pacific in 1997–1998 and the rapid transition to strong La Niña conditions in 1998–1999 had a large impact on the physical and biological environment of the West Coast. We investigate the evolution of the physical structure and circulation dynamics of the southern California Current System (CCS) during this period based on hydrographic data collected on 25 cruises over a 45-month period (February 1996–October 1999). The El Niño period was characterized by a significant increase in dynamic height, extreme water mass characteristics, a strengthening and broadening of the poleward nearshore flow, and a temporary reversal of net alongshore transport. By early 1999, conditions in the CCS had reversed. The data suggest that remotely driven forcing (propagating oceanic waves) contributed to the anomalies observed during the El Niño period, while the cool-water conditions of 1999 were most likely a result of anomalous local atmospheric forcing.     

Nutrient variability during El Niño 1997–98 in the California current system off central California

Nutrient conditions off central California during the 1997–98 El Niño are described. Data were collected on 11 cruises from March 1997 to January 1999 along a hydrographic section off central California, as well as every two weeks at a coastal station in Monterey Bay. Perturbations associated with El Niño are shown as anomalies of thermohaline and nutrient distributions along this section. The anomalies were obtained by subtracting seasonal averages for the period from April 1988 to April 1991 from the 1997–98 observations. The first indications of El Niño conditions (high sea levels) were observed at Monterey between late May and early June 1997, but the coastal nutricline did not begin to deepen until August 1997. It reached maximum depth of 130 dbar in January 1998 at the time that maximum sea level anomalies were observed. During this period: (1) the highest subsurface temperature anomalies coincided with subsurface nutrient anomaly minima at the depth of the pycnocline; (2) southern saline and nutrient-poor waters occupied the upper 80 dbar of the water column along the entire section; and (3) nitrate levels were close to zero in the euphotic zone, collapsing the potential new primary production in the coastal domain. At the end of February 1998, the nutricline shoaled to 40 dbar at the coast although it remained anomalously deep offshore. Higher temperatures and lower nutrient levels were observed for the entire section through August 1998 although in contrast with the previous winter, there was a strong freshening mainly due to an onshore movement of subarctic waters.     

Study of macroaggregate composition using FT-IR and H-NMR spectroscopy

Mucous macroaggregates, recently observed in the northern Adriatic in summer of 1997 and late spring of 2000, are primarily the product of phytoplankton (diatom) exudates during favourable environmental conditions in late spring, and can be viewed as macrogels. The FT-IR and ¹H-NMR spectra of macroaggregate samples from the northern Adriatic, collected in different formation stages in July 1997, August 1997, September 1997 and June 2000, as well as of cultured diatom Skeletonema costatum, showed that they are similar and composed of aliphatic components and polysaccharides bonded through carboxylic and amide groups, and organosilicon compounds. The stability of macrogels of macroaggregates is, according to FT-IR and X-ray analyses, most probably enhanced by interactions with entrapped particles of calcite, quartz and clay minerals. These organic-mineral associations seem to be important for mucous phenomena. According to ¹H-NMR spectra, the temporal differences in macroaggregate composition show a relative increasing percentage of organosilicon compounds and aliphatic components bonded to carbohydrates through ester and amide groups, and an increasing ratio between aliphatic structures and carbohydrates. This indicates that aliphatic chains bonded to Si and carbohydrates may contribute to the persistence and stability of macroaggregates in the summer stratified waters in the northern Adriatic, while the temporal decrease of carbohydrate content is most probably due to microbial and photochemical degradation of algal reserve polysaccharides.     

Industry participation in stock assessment: the New Zealand SNA1 snapper (Pagrus auratus) fishery

We describe industry funded contributions to the assessment of the SNA1 snapper (Pagrus auratus) fishery during the 1990s and discuss the advantages and disadvantages of industry funded research. We also provide background on the history of fisheries management in New Zealand, on the current assessment and management processes, and on the SNA1 snapper fishery. In the SNA1 fishery, the contributions of industry and the cooperation with Government scientists has resulted in high quality assessments. In our opinion, the advantages of industry funded research out weigh the disadvantages and suggest that industry funded assessments are highly desirable and should be an integral part of any management system.