Nocturnal behavior of gulls in coastal New Jersey

We studied the behavior of gulls at night with an image intensifier telescope to determine whether they were active at night, and the extent of their foraging in coastal habitats of New Jersey in the summer, fall, and winter of 1989–1990. Regression models and Kruskal-Wallis tests indicated that date, time of day, tide, cloud cover, moon phase, and study location all influenced variations in the presence and nocturnal activities of gulls. For each site and species, an, average of 48–88% of the nocturnal surveys recorded gulls foraging or flying about. More laughing gulls (Larus atricilla) foraged at night at Brigantine Beach compared to ring-billed gulls (L. delawarensis) at the northern New Jersey sites. However, more gulls were flying about at the Raritan River site compared to the other places. We suggest that more laughing gulls fed at night compared to ring-billed gulls because the former were breeding. Breeding gulls spend half their time incubating or caring for chicks, and thus might have time constraints on foraging during the day. Laughing gulls foraged at all times of the night on some surveys, but were more frequent around midnight, and the number of flying laughing gulls decreased after 0200 hours. Ring-billed gulls, however, seemed to be equally active all night. Our data indicate that gulls can be active all night, and in all habitats.     

The effect of human disturbance on foraging behavior and habitat use in piping plover (Charadrius melodus)

Piping plovers breed in coastal areas where they experience intense competition with man. I studied habitat use (using transects) and foraging behavior (using focal animals) at three habitats on each of three nesting beaches over a 2-yr period (1988–1989) in New Jersey, USA, to understand how plovers use space. Piping plovers forage along in tidal oceanfront, in the dunes, and in backbays, and their relative use of tehse habitats partially depends on the presence of people. Within each habitat the plovers select sites that contain fewer people than the habitat as a whole. The time devoted to vigilance (when they are not searching for food) is directly related to the number of people near them, and to the overall human use of that habitat. Thus, in habitats with few people the plovers can spend 90% of their foraging time actively searching for prey and feeding, whereas on beaches with many people they may spend less than 50% of their foraging time in direct feeding behaviors. A diversity of habitats allows the birds to move between habitats to minimize interactions with people and maximize the time devoted to foraging. The results suggest that it is critical to maintain high habitat diversity in coastal environments to help mitigate competition with people.     

Rb‐Sr and Sm‐Nd isotopic and REE studies of igneous components in the bulk matrix domain of Martian breccia Northwest Africa 7034

The bulk matrix domain of the Martian breccia NWA 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia. Both ¹⁴⁷Sm‐¹⁴³Nd and ¹⁴⁶Sm‐¹⁴²Nd age results for mineral separates from the bulk matrix portion of breccia NWA 7034 suggest that various lithological components in the breccia probably formed contemporaneously ~4.44 Ga ago. This old age is in excellent agreement with the upper intersection ages (4.35–4.45 Ga) for U‐Pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous‐textured clasts. Consequently, we confirm an ancient age for the igneous components that make up the NWA 7034 breccia. Substantial disturbance in the Rb‐Sr system was detected, and no age significance could be gleaned from our Rb‐Sr data. The disturbance to the Rb‐Sr system may be due to a thermal event recorded by bulk‐rock K‐Ar ages of 1.56 Ga and U‐Pb ages of phosphates at about 1.35–1.5 Ga, which suggest partial resetting from an unknown thermal event(s), possibly accompanying breccia formation. The NWA 7034 bulk rock is LREE enriched and similar to KREEP‐rich lunar rocks, which indicates that the earliest Martian crust was geochemically enriched. This enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on Mars that have been detected in studies of other Martian meteorites.     

Non-basaltic asteroidal magmatism during the earliest stages of solar system evolution: A view from Antarctic achondrites Graves Nunatak 06128 and 06129

The recently recovered paired Antarctic achondrites Graves Nunatak 06128 and 06129 (GRA) are meteorites that represent unique high-temperature asteroidal processes that are identified in only a few other meteorites. The GRA meteorites contain high abundances of sodic plagioclase, relatively Fe-rich pyroxenes and olivine, abundant phosphates, and low temperature alteration. They represent products of very early planetesimal melting (4565.9 ± 0.3 Ma) of an unsampled geochemical reservoir from an asteroid that has characteristics similar to the brachinite parent body. The magmatism represented by these meteorites is contrary to the commonly held belief that the earliest stages of melting on all planetary bodies during the first 2-30 Ma of solar system history were fundamentally basaltic in nature. These sodic plagioclase-rich rocks represent a series of early asteroidal high-temperature processes: (stage 1) melting and partial extraction of a low-temperature Fe-Ni-S melt, (stage 2) small degrees of disequilibrium partial melting of a sodium- or alkali-rich chondritic parent body with additional incorporation of Fe-Ni-S melt that was not fully extracted during stage 1, (stage 3) volatile-enhanced rapid extraction and emplacement of the Na-rich, high-normative plagioclase melt, (stage 4) final emplacement and accumulation of plagioclase and phosphates, (stage 5) subsolidus reequilibration of lithology between 962 and 600 °C at an fO₂ of IW to IW + 1.1, and (stage 6) replacement of merrillite and pyroxene by Cl-apatite resulting from the interaction between magmatic minerals and a Cl-rich fluid/residuum melt. The subsolidus events started as early as 4561.1 Ma and may have continued for upwards of 144 million years.The existence of assemblages similar to GRA on several other planetary bodies with different geochemical characteristics (ureilite, winonaites, IAB irons) implies that this type of early asteroidal melting was not rare. Whereas, eucrites and angrites represent extensive melting of a parent body with low concentrations of moderately-volatile elements, GRA represents low-degrees of melting of a parent body with chondritic abundances of moderately volatile elements. The interpretation of the low-temperature mineral assemblage is somewhat ambiguous. Textural features suggest multiple episodes of alteration. The earliest stage follows the interaction of magmatic assemblages with a Cl-rich fluid. The last episode of alteration appears to cross-cut the fusion crust and earlier stages of alteration. Stable isotopic measurements of the alteration can be interpreted as indicating that an extraterrestrial volatile component was preserved in GRA.     

Petrogenetic relationships between diogenites and olivine diogenites: Implications for magmatism on the HED parent body

Diogenites are orthopyroxenites and harzburgites that are petrogenetically associated with basaltic magmatism linked to the earliest stages of asteroidal melting on the parent body for the howardite-eucrite-diogenite (HED) meteorites. There are several models proposed for their origin: (1) accumulation of orthopyroxene (OPX) + chromite (CHR) ± olivine (OL) during the crystallization of a magma ocean during the initial stages of asteroidal differentiation, (2) accumulation of OPX + CHR ± OL during the crystallization of compositionally distinct basaltic magmas emplaced into the crust of the HED parent body, and (3) the orthopyroxenites formed by the crystallization of basaltic magmas within the HED parent body crust, whereas the harzburgites represent the mantle of the HED parent body. Although OL and OPX experienced varying degrees of subsolidus reequilibration (1100-700 °C), their minor and trace element characteristics appear to partially preserve magmatic signatures that provide insights into distinguishing among different models for the origin of diogenites. The OPX exhibits a continuous and very systematic variation in incompatible elements such as Al, Ti, Zr, Y, and Yb. Polymict diogenites (i.e. Roda, EET 79002) can contain distinct lithologies with both different incompatible element characteristics and different model abundances of OL. There appears to be no relationship between the appearance and abundance of OL and the incompatible element characteristics of the OPX. The OL exhibits a range in Mg# and systematic variations Ni, Co, Ni/Co, and Mn. For examples, low Ni/Co appears to be closely associated with the harzburgites and Ni and Mn exhibit a negative correlation. Surprisingly, incompatible element concentrations in OPX are not negatively correlated to Ni concentrations in OL. The continuous nature of the minor and trace element characteristics of the OPX and OL is consistent with the all the diogenite lithologies forming through a single process such as crystallization within a magma ocean or a series of layered intrusions. Further, the range in incompatible element variability in the OPX, the Ni and Co systematics in the OL, and the association of distinctly different lithologies within polymict diogenites are most consistent with the diogenites representing lithologies from diverse layered intrusions. Alternatively, they may represent crystallization products of a magma ocean much more complex than has been thus far proposed (i.e. multiple MOs). There are some distinct differences between diogenites and the OL-rich achondrite QUE 93148 that was also analyzed during this study. These differences (such as Ni/Co in OL, estimated conditions of f_O2) suggest that QUE 93148 is closely related to main-group pallasites rather than the parent bodies for the HED meteorites.     

The chlorine isotopic composition of Martian meteorites 1: Chlorine isotope composition of Martian mantle and crustal reservoirs and their interactions

The Martian meteorites record a wide diversity of environments, processes, and ages. Much work has been done to decipher potential mantle sources for Martian magmas and their interactions with crustal and surface environments. Chlorine isotopes provide a unique opportunity to assess interactions between Martian mantle‐derived magmas and the crust. We have measured the Cl‐isotopic composition of 17 samples that span the range of known ages, Martian environments, and mantle reservoirs. The ³⁷Cl of the Martian mantle, as represented by the olivine‐phyric shergottites, NWA 2737 (chassignite), and Shergotty (basaltic shergottite), has a low value of approximately ?3.8‰. This value is lower than that of all other planetary bodies measured thus far. The Martian crust, as represented by regolith breccia NWA 7034, is variably enriched in the heavy isotope of Cl. This enrichment is reflective of preferential loss of ³⁵Cl to space. Most basaltic shergottites (less Shergotty), nakhlites, Chassigny, and Allan Hills 84001 lie on a continuum between the Martian mantle and crust. This intermediate range is explained by mechanical mixing through impact, fluid interaction, and assimilation‐fractional crystallization.     

Equator-pole effect in the central intensities of some strong solar Fraunhofer lines

Uncorrected central intensities of the Fraunhofer lines NaD₁ and D₂, Mgb₁ and b₂, and Hβ have been determined at a number of points along the S-W limb of the sun, from equator to pole, using photographic spectra taken at the Locarno station of the Göttingen Observatory. No significant pole-equator variation could be found in excess of the observational errors which are of the order of 2%.     

The development of a physiologically-based pharmacokinetic model using the distribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the tissues of the eastern oyster (Crassostrea virginica)

A physiologically-based pharmacokinetic model (PBPK) was developed to describe the kinetics of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the eastern oyster (Crassostrea virginica). The estimated t(1/2) of elimination for a bolus dose of TCDD in C. virginica is approximately 14-24 days based on both the experimental data and the PBPK model. The highest dioxin concentration reached during 28-days was in the digestive gland followed by the mantle, gonad, hemolymph, gill, adductor muscle, and the kidney/heart. A binding protein for 2,3,7,8-TCDD had been reported in the literature for both the digestive gland and gonad. Incorporating a binding component in the model resulted in a better fit for the data. The PBPK model predicted the distribution and the elimination concentrations for 2,3,7,8-TCDD within each of the tissue compartments. This model will serve as a useful tool for predicting the kinetics of other persistent organic pollutants as well as, allow for a more refined ecological risk assessment by estimating dioxin concentrations in sensitive tissues such as the gonad.