Essential Fish Habitat and Wetland Restoration Success: A Tier III Approach to the Biochemical Condition of Common Mummichog Fundulus heteroclitus in Common Reed Phragmites australis- and Smooth Cordgrass Spartina alterniflora-Dominated Salt Marshes

A tier III, essential fish habitat analysis was used to evaluate the biochemical condition of common mummichog Fundulus heteroclitus residing in two isolated tidal salt marshes, one a relatively undisturbed polyhaline site dominated by Spartina alterniflora and the other a meso-oligohaline site dominated by an invasive variety of Phragmites australis. Stable isotopes signatures of C, N, and S in whole tissue samples of F. heteroclitus were used to compare the trophic spectrum for this species in each marsh as a function of the dominant macrophytes present with additional contributions from phytoplankton and benthic microalgae. Allometry of wet mass and its components, water mass, lean protein mass and lipid mass in individual fish exhibited hyperallometric patterns; and average lipid mass fell within the range reported for most fundulids, including F. heteroclitus. Significant differences were also detected in the allocation of lipid classes to energy reserves in the form of triacylglycerols (TAG) and free fatty acids. These reserves, especially TAG, are critical for reproduction, migration, and overwintering survival in many taxa and were significantly lower in fish collected in the P. australis-dominated marsh. Relative to the relatively undisturbed Spartina-dominated site, we tentatively conclude that the P. australis-invaded marsh was an inferior habitat for F. heteroclitus.     

Population dynamics of spot,leiostomus xanthurus,in polyhaline tidal creeks of the York River estuary,Virginia

Most populations of estuarine-dependent, early life stages of marine fishes are open. As a result, it has been difficult to apply conventional population models to most systems. In this study, a marked population of young-of-year spot (Leiostomus xanthurus) was released into a polyhaline tidal creek within the Guinea Marshes of the York River estuary, Virginia. Over a 90-day study period, 221 marked fishes were recaptured. Plots of the ratio of marked to unmarked individuals (m_i/n_i) in subsequent samples indicated that the population was resident in the creek for up to 162 days with the average individual present for 81 days. When this population turnover rate was compared to the total population decay rate (marked plus unmarked fish), it was determined that exchange between habitats (immigration/emigration) accounted for about 36.4% of the total decay rate, with the remainder attributed to natural mortality. By correcting the overall disappearance rate for population turnover due to emigration and using this adjusted value as a measure of instantaneous mortality (z), the estimated production (over 90 days) in this population was 23,630 cal (98,870 J) per m². This figure agrees with a previously derived estimate for spot in the Guinea marshes and is nearly two orders of magnitude higher than other reported values for this species for all size classes over the entire growing season.     

Habitat disturbance and marina development: An assessment of ecological effects. I. Changes in primary production due to dredging and marina construction

Potential impacts on primary production were estimated for an 800-slip marina previously planned for Davids Island, located in the extreme western portion of Long Island Sound, New York. Macroalgal and microalgal production in the area of the proposed marina was analyzed on the basis of six depth zones ranging from an existing seawall (at about +2.2 m MLW) seaward to a depth of ?2.4 m MLW. Productivity measurements were based on in situ ¹⁴C uptake studies, chlorophyll a determinations, and varying light exposures within the euphotic zone that were the estimate of daily production calculated for eight dominant macroalgae and microalgae, and summed to estimate existing production in the proposed marina. Similarly, post-construction production was estimated by applying the calculated daily production to the appropriate areas of hard substrate (breakwater, pilings, etc.) in the euphotic zone. Pre- and post-construction macroalgal production values were 50,608 and 42,152 g C d^?1, respectively. This represents a 17% reduction in macroalgal production. It should be noted, however, that production on the seafloor of the marina was not accounted for. Consquently, reductions in macroalgal production that might occur are likely overestimated. Microalgal production constituted less than 3% of total primary production in the nearshore areas of Davids Island. The pre- and post-construction microalgal production values were 1,542 and 743 g C d^?1, respectively. This represents a 48% reduction in microalgal production in unconsolidated sediment. However, micoalgal production would likely occur on hard substrates in the marina. Overall, pre- and post-construction estimates of primary production were remarkably similar, suggesting that production on hard substrates in the marina would compensate for lost production from deepening of the nearshore zone during construction. *** DIRECT SUPPORT *** A01BY074 00012     

Finite Fault Modeling in a Tsunami Warning Center Context

The US NOAA/NWS tsunami warning centers have relied on earthquake location and depth, and scalar measures of earthquake size and slowness to assess the potential for the generation of a destructive tsunami by an earthquake. Recent earthquakes, such as Peru 2001, Sumatra 2004 and the Java 2006, manifest some of the difficulties the warning centers face as they try to cope with unusual earthquakes. We have undertaken a study of a simple teleseismic waveform inverse model and applied it to the earthquakes of June 23, 2001 in Peru and of July 17, 2006 in Java. Synthetic numerical experiments suggest that the most salient features of the rupture history of an earthquake can be recovered. Furthermore the calculations can be conducted quickly enough to be useful in a warning center context. We have applied our technique to the Peru 2001 and recent Java 2006 earthquakes. Our overall results are consistent with those obtained from other studies. The results show why the Peru event initially looked slow to the US tsunami warning centers and that the Java event is a truly slow or tsunami earthquake. Clearly, the warning centers stand to benefit from an increased understanding of the earthquakes they monitor. Furthermore, better knowledge of the slip distribution along a fault will improve tsunami wave-height forecasts.     

A STATISTICAL TEST OF FLORISTIC ZONES AS INFERRED FROM THE POLLEN RECORD: SOUTHERN NEW ENGLAND

This study presents the stratigraphic and floristic interpretations of data collected from a 6.49 m core taken within the Rowley River Marsh, Massachusetts. Twenty-five samples were collected at 28 centimeter intervals from the core in this Holocene coastal marsh. Based on stratigraphic control, the age of the core samples includes a time sequence extending back 4,600 years from the present. Analysis of the core stratigraphic units suggests the environment has essentially been a low energy estuarine system for the past 4,600 years. The 25 samples were also processed for pollen taxa present since 4,600 years B.P. A discriminant function analysis was used to test the floristic zonal similarity of the diagnostic taxa (Picea, Pinus, Carya, Tsuga, Quercus) from the core with those same taxa used to establish the floristic zones for the southern New England region. The results of the analysis demonstrated that 84% of the samples were correctly classified by floristic zone. Although the distribution of diagnostic taxa from this study is generally in agreement with the previously established floristic zones, the Tsuga taxa are present throughout the temporal sequence, suggesting the occurrence of a cooler climate regime for the sampling site since 4,600 years B.P.     

Koolau shield basalt as xenoliths entrained during rejuvenated-stage eruptions: perspectives on magma mixing

Rejuvenated-stage tuff cones (Honolulu Volcanics) on Koolau volcano, Oahu, Hawaii, contain xenoliths of Koolau shield basalt. Because Koolau subaerial shield lavas represent a Hawaiian geochemical 'end member', and submarine shield lavas have compositions with some affinities to Mauna Loa and Kilauea, we analyzed 28 xenolithic basalts from Salt Lake and Koko Head cones to determine how these seemingly random samplings of the Koolau profile compare to established Koolau geochemistry. Analyses reveal that 24 are shield tholeiitic basalt—the focus of this study—and 4 are rejuvenated-stage basaltic rocks. The tholeiitic xenoliths represent largely upper Koolau shield lavas, as these samples (8.3 to 5.8 wt% MgO) have, with one exception, overall major- and trace-element compositions that overlap those of Koolau subaerial shield lavas. Secondary processes, however, created some distinctions—namely, enrichments/depletions in K, Ba, Sr, SiO₂, and FeO, and, due to zeolitization (chabazite with attending okenite and apophyllite), elevated CaO. One xenolithic basalt with 8.2 wt% MgO has higher Ti, Zr, Nb, and Sc, and lower Zr/Nb than subaerial lavas, and appears to represent relatively early, deeper shield—thereby reinforcing that the Koolau shield source varied temporally. Olivine, orthopyroxene, and plagioclase are the phenocrysts (clinopyroxene is rare), and their core compositions range widely across the suite—Fo_87.8–72, orthopyroxene Mg#s 85–72, and An_74–60. Several xenolithic basalts have both normally and reversely zoned orthopyroxene and plagioclase with a variety of core compositions (e.g., orthopyroxene-core Mg#s 82, 77, and 72, all in one sample). These compositions and zonations record evidence for wide compositional ranges of replenishment (MgO ~13–8 wt%) and reservoir (MgO ~7 to <5 wt%) magmas mixing in varying proportions; however, extreme MgO lavas (~13 and <5 wt%) are not observed as either subaerial or xenolithic basalt, but are indicated by phenocryst cores of Fo_87.8 and orthopyroxene-Mg# 72. The Koolau magma-mixing history resembles that of Kilauea, and is unlike the 'steady-state' mixing known for Mauna Loa. Finally, these basalt samples show that any xenolithic occurrence of Koolau lava is subject to the zeolitization prevalent in the tuff-cone hosts.Editorial handling: M. Carroll     

Spatial and temporal geochemical variability in basin-related volcanism, northern Israel

Middle Miocene (17-9 Ma) volcanism in northeast Israel migrated from eastern Lower Galilee (Poria, west of the Sea of Galilee) to the southwest (Yizre'el Valley) in association with the development of an extensional basin in that area. The Yizre'el Valley magmas are highly undersaturated in silica (basanites and nephelinites), while those of Poria are alkali-basaltic. Scarce Middle Miocene basalts from the Golan, further to the east, are also alkali-basaltic. Magmas from Kaukab (southeastern Lower Galilee) show a range of compositions from alkali-basalts to basanites. The patterns defined by ratios versus concentrations of incompatible elements in Kaukab basalts (e.g. versus La), as well as the scatter observed in Sr isotope ratios, are interpreted in terms of binary mixing. It is suggested that the Kaukab magmas were derived from veined lithospheric peridotites, melts of the veins and of the peridotites being the two end-members. Accordingly, alkali-basaltic- and basanite-dominated areas are underlain by vein-poor and vein-rich lithosphere, respectively. It is also suggested that melting during the Middle Miocene mainly occurred in response to extension, and that it followed the propagation of the Yizre'el-Galilee Basin from northeast to southwest.