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M.A. Ricca

Publications and source records attributed to M.A. Ricca.

12 recordsLinked to original sources
USGS2010

Temporal and spatial distributions of sediment mercury at salt pond wetland restoration sites, San Francisco Bay, CA, USA

Decommissioned agricultural salt ponds within south San Francisco Bay, California, are in the process of being converted to habitat for the benefit of wildlife as well as water management needs and recreation. Little is known of baseline levels of contaminants in these ponds, particularly mercury (Hg), which has a well established legacy in the Bay. In this study we described spatial and short-term temporal variations in sediment Hg species concentrations within and among the Alviso and Eden Landing salt ponds in the southern region of San Francisco Bay. We determined total Hg (Hg t ) and methylmercury (MeHg) in the top 5 cm of sediment of most ponds in order to establish baseline conditions prior to restoration, sediment Hg t concentrations in a subset of these ponds after commencement of restoration, and variation in MeHg concentrations relative to sediment Hg t , pH, and total Fe concentrations and water depth and salinity in the subset of Alviso ponds. Inter-pond differences were greatest within the Alviso pond complex, where sediment Hg t concentrations averaged (arithmetic mean) 0.74 [mu]g/g pre and 1.03 [mu]g/g post-restoration activity compared to 0.11 [mu]g/g pre and post at Eden Landing ponds. Sediment Hg t levels at Alviso were fairly stable temporally and spatially, whereas MeHg levels were variable relative to restoration activities across time and space. Mean (arithmetic) sediment MeHg concentrations increased (2.58 to 3.03 ng/g) in Alviso and decreased (2.20 to 1.03 ng/g) in Eden Landing restoration ponds during the study. Differences in MeHg levels were related to water depth and pH, but these relationships were not consistent between years or among ponds and were viewed with caution. Factors affecting MeHg levels in these ponds (and in general) are highly complex and require in-depth study to understand.

Science of the Total Environment↗
USGS2008

Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades.

Because sea otters ( Enhydra lutris ) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles ( Haliaeetus leucocephalus ) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993–1994 and 2000–2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993–1994 to 2000–2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling ( Hexagammus lagocephalus ), and smooth lumpsuckers ( Aptocyclus ventricosus ) in the eagle's diet declined with corresponding increases in Rock Ptarmigan ( Lagopus mutus ), Glaucous-winged Gulls ( Larus glaucescens ), Atka mackerel ( Pleurogrammus monopterygius ), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator to another.

Ecology↗
USGS2007

Polycyclic aromatic hydrocarbon exposure in Steller's eiders ( Polysticta stelleri ) and harlequin ducks ( Histronicus histronicus ) in the Eastern Aleutian Islands, Alaska, USA

Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin- O -deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders ( Polysticta stelleri ) and Harlequin ducks ( Histronicus histronicus ) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([ Mytilus trossilus ] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (∼1,180–5,980 ng/g) approached those found at highly contaminated sites (∼4,100–7,500 ng/g).

Environmental Toxicology and Chemistry↗
USGS2007

Environmental contaminants in bald eagle eggs from the Aleutian archipelago

We collected 136 fresh and unhatched eggs from bald eagle (Haliaeetus leucocephalus) nests and assessed productivity on eight islands in the Aleutian archipelago, 2000 to 2002. Egg contents were analyzed for a broad spectrum of organochlorine (OC) contaminants, mercury (Hg), and stable isotopes of carbon (??13C) and nitrogen (??15N). Concentrations of polychlorinated biphenyls (??PCBs), p,p???- dichlorodiphenyldichloroethylene (DDE), and Hg in bald eagle eggs were elevated throughout the archipelago, but the patterns of distribution differed among the various contaminants. Total PCBs were highest in areas of past military activities on Adak and Amchitka Islands, indicating local point sources of these compounds. Concentrations of DDE and Hg were higher on Amchitka Island, which was subjected to much military activity during World War II and the middle of the 20th century. Concentrations of ??PCBs also were elevated on islands with little history of military activity (e.g., Amlia, Tanaga, Buldir), suggesting non-point sources of PCBs in addition to point sources. Concentrations of DDE and Hg were highest in eagle eggs from the most western Aleutian Islands (e.g., Buldir, Kiska) and decreased eastward along the Aleutian chain. This east-to-west increase suggested a Eurasian source of contamination, possibly through global transport and atmospheric distillation and/or from migratory seabirds. Eggshell thickness and productivity of bald eagles were normal and indicative of healthy populations because concentrations of most contaminants were below threshold levels for effects on reproduction. Contrary to our predictions, contaminant concentrations were not correlated with stable isotopes of carbon (??13C) or nitrogen (??15N) in eggs. These latter findings indicate that contaminant concentrations were influenced more by point sources and geographic location than trophic status of eagles among the different islands. ?? 2007 SETAC.

Environmental Toxicology and Chemistry↗
USGS2007

Effect of lipid extraction on analyses of stable carbon and stable nitrogen isotopes in coastal organisms of the Aleutian archipelago

We tested whether extracting lipids reduced confounding variation in ??13C and ??15N values by analyzing paired lipid-extracted (LE) and non-lipid-extracted (NLE) samples of bald eagle (Haliaeetus leucocephalus (L., 1766)) whole eggs, muscle tissue from nine seabird and one terrestrial bird species, muscle tissue from four marine fish species, and blue mussels (Mytilus edulis L., 1758) collected from the Aleutian archipelago, Alaska. Lipid extraction significantly increased ??13C by an average of 2.0??? in whole eggs, 0.8??? in avian muscle, 0.2??? in fish muscle, and 0.6??? in blue mussels. Lower ??13C values in NLE samples covaried positively with lipid content across all sample types. Lower ??13C values in NLE samples were not correlated with lipid content within bald eagle eggs and blue mussels, but covaried positively with percent lipid in avian and fish muscles. Neither lipid extraction nor percent lipid significantly changed ??15N values for any sample type. Lower ??13C values in most NLE avian and fish muscle tissues should not confound interpretation of pelagic versus nearshore sources of primary production, but lipid extraction may be necessary when highly precise estimates of ??13C are needed. Lipid extraction may not be necessary when only ??15N is of interest. ?? 2007 NRC.

Canadian Journal of Zoology↗
USGS2003

Body weight and rumen-reticulum capacity in tule elk and mule deer

The relationship between body size and rumen-reticulum capacity among conspecific individuals is predicted to be isometric. We examined whether the relationship between body weight and rumen-reticulum capacity was isometric in adult male and female rule elk (Cervus elaphus nannodes) and in adult female mule deer (Odocoileus hemionus). We detected no effect of sex on this relationship in elk, and the slope of the regression was 1.0 for one measure of rumen-reticulum capacity and <1.0 for another. Among deer, the slope of the relationship was <1.0 in one measure of rumen-reticulum capacity, and we detected no relationship with the other.

Journal of Mammalogy↗
USGS2003

Spatial use and habitat associations of Columbian white-tailed deer fawns in southwestern Oregon

Fawns represent a critical life history stage in the dynamics of deer populations, yet little recent information is available on the ecology of neonatal Columbian white-tailed deer (CWTD), a geographically isolated and federally endangered sub-species. We described home ranges, areas of concentrated use, and habitat associations of CWTD fawns in southwestern Oregon during the summers of 1997 and 1998. Spatial use patterns and habitat use within areas of concentrated use were described for 11 radio-marked fawns. Pooled habitat use was described for 24 radio-marked fawns. Areas of concentrated use averaged 2.4 ha, which was 13.3% of mean 95% home range size (18.0 ha). Frequent use of oak-madrone woodland and riparian cover types characterized fawn habitat use patterns. Cover types containing conifers were rarely used and usually not available within home ranges. Although we found no detectable patterns of habitat selection or avoidance among fawns, areas of concentrated use were composed mostly of oak-madrone woodland (35%) and riparian (26%) cover types. Moreover, 74% of concentrated use area was within 200 m of streams. Our results provide useful information on habitat characteristics used frequently by CWTD fawns.

Northwest Science↗