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M. K. Saiki

Publications and source records attributed to M. K. Saiki.

15 recordsLinked to original sources
USGS2009

Utilization by fishes of the Alviso Island ponds and adjacent waters in south san francisco bay following restoration to tidal influence

Earthen levees of three isolated salt ponds known locally as the Alviso Island Ponds were intentionally breached in March 2006 to allow tidal exchange of the ponds with water from Coyote Creek. The water exchange transformed the previously fishless hypersaline ponds into lower salinity habitats suitable for fish life. This study documented fish utilization of the ponds, adjacent reaches of Coyote Creek, and an upstream reach in nearby Artesian Slough during May-July 2006. By the time the study was initiated, water quality conditions in the ponds were similar to conditions in adjacent reaches of Coyote Creek. The only variable exhibiting a strong gradient within the study area was salinity, which increased progressively from upstream to downstream in Coyote Creek. A total of 4,034 fish represented by 18 species from 14 families was caught during the study. Judging from cluster analysis of presence-absence data that excluded rare fish species, the 10 sampling units (3 ponds, 6 reaches in Coyote Creek, and 1 reach in Artesian Slough) formed two clusters or groups, suggesting two species assemblages. The existence of two groups was also suggested by ordination with non-metric multidimensional scaling (NMS). One group, which was composed of the three ponds and four of the lowermost reaches of Coyote Creek, was characterized by mostly estuarine or marine species (e.g., topsmelt, Atherinops affinis; northern anchovy, Engraulis mordax; and longjaw mudsucker, Gillichthys mirabilis). The second group, which was composed of the two uppermost reaches of Coyote Creek and the one reach of Artesian Slough, was characterized by freshwater species (e.g., Sacramento sucker, Catostomus occidentalis) and by an absence of the estuarine/marine species noted in the first assemblage. Judging from a joint plot of selected water quality variables overlaying the ordination results, salinity was the only important variable associated with spatial distribution of fish species. Water temperature, dissolved oxygen, and pH had little influence on fish distribution during this study.

California Fish and Game↗
USGS2006

Trophic structure and avian communities across a salinity gradient in evaporation ponds of the San Francisco Bay estuary

Commercial salt evaporation ponds comprise a large proportion of baylands adjacent to the San Francisco Bay, a highly urbanized estuary. In the past two centuries, more than 79% of the historic tidal wetlands in this estuary have been lost. Resource management agencies have acquired more than 10 000 ha of commercial salt ponds with plans to undertake one of the largest wetland restoration projects in North America. However, these plans have created debate about the ecological importance of salt ponds for migratory bird communities in western North America. Salt ponds are unique mesohaline (5–18 g l −1 ) to hyperhaline (> 40 g l −1 ) wetlands, but little is known of their ecological structure or value. Thus, we studied decommissioned salt ponds in the North Bay of the San Francisco Bay estuary from January 1999 through November 2001. We measured water quality parameters (salinity, DO, pH, temperature), nutrient concentrations, primary productivity, zooplankton, macroinvertebrates, fish, and birds across a range of salinities from 24 to 264 g l −1 . Our studies documented how unique limnological characteristics of salt ponds were related to nutrient levels, primary productivity rates, invertebrate biomass and taxa richness, prey fish, and avian predator numbers. Salt ponds were shown to have unique trophic and physical attributes that supported large numbers of migratory birds. Therefore, managers should carefully weigh the benefits of increasing habitat for native tidal marsh species with the costs of losing these unique hypersaline systems.

California↗
USGS2005

Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

California↗
USGS2005

Total mercury concentrations in fillets of bluegill, redear sunfish, largemouth bass, and other fishes from Lake Natoma, Sacramento County, California

This study was conducted during September-October 2002 to verify preliminary findings of elevated total mercury concentrations in skinless fillets of sportfishes inhabiting Lake Natoma. Although we measured total mercury concentrations, most mercury in fish flesh occurs in the methylated form. In August 2000, other investigators collected a small number of fish containing mercury concentrations that exceeded 0.30 ??g/g wet weight, the U.S. Environmental Protection Agency (USEPA) tissue residue criterion derived from a reference dose for methylmercury that may cause undesirable neurological abnormalities in human infants exposed in utero when pregnant women consume mercury-contaminated foods. During our study, skinless fillets of bluegill, Lepomis macrochirus, contained as much as 0.19 ??g Hg/g wet weight (1.06 ??g Hg/g dry weight); redear sunfish, L. microlophus, contained as much as 0.39 ??g Hg/g wetweight (1.99 ??g Hg/g dry weight); and largemouth bass, Micropterus salmoides, contained as much as 0.86 ??g Hg/g wet weight (3.85 ??g Hg/g dry weight). Maximum concentrations of mercury in other fish species varied from 0.097 ??g/g wet weight (0.537 ??g/g dry weight) in rainbow trout, Oncorhynchus mykiss, to 0.56 ??g/g wet weight (3.07 ??g/g dry weight) in white catfish, Ameiurus catus. Altogether, 1 of 20 redear sunfish, 14 of 61 largemouth bass, 1 of 1 brown builhead, A. nebulosus, 2 of 3 spotted bass, M. punctulatus, and 1 of 1 white catfish exceeded the USEPA fish tissue methylmercury residue criterion. Only bluegill and largemouth bass exhibited significant correlations between fish total length (TL), weight, and age, and total mercury concentration in fillets. Judging from a best-fit power-curve equation, largemouth bass measuring 273 mm TL (roughly 292g) or larger are estimated to contain total mercury concentrations in their fillets that exceed the USEPA fish tissue methylmercury criterion. These results confirmed that some fish species inhabiting Lake Natoma are contaminated with undesirably high concentrations of mercury in their skinless fillets.

California Fish and Game↗
USGS2001

Effects of an agricultural drainwater bypass on fishes inhabiting the Grassland Water District and the lower San Joaquin River, California

The Grassland Bypass Project, which began operation in September 1996, was conceived as a means of diverting brackish selenium-contaminated agricultural drainwater away from canals and sloughs needed for transporting irrigation water to wetlands within the Grassland Water District (the Grasslands), Merced County, California. The seleniferous drainwater is now routed into the San Luis Drain for conveyance to North Mud Slough and eventual disposal in the San Joaquin River. The purpose of this study was to determine the extent to which the Grassland Bypass Project has affected fishes in sloughs and other surface waters within and downstream from the Grasslands. During September-October 1997, 9,795 fish representing 25 species were captured at 13 sampling sites. Although several species exhibited restricted spatial distributions, association analysis and cluster analysis failed to identify more than one fish species assemblage inhabiting the various sites. However, seleniferous drainwater from the San Luis Drain has influenced selenium concentrations in whole fish within North Mud Slough and the San Joaquin River. The highest concentrations of selenium (12-23 ??g/g, dry weight basis) were measured in green sunfish Lepomis cyanellus from the San Luis Drain where seleniferous drainwater is most concentrated, whereas the second highest concentrations occurred in green sunfish (7.6-17 ??g/g) and bluegills Lepomis macrochirus (14-18 ??g/g) from North Mud Slough immediately downstream from the drain. Although there was some variation, fish in the San Joaquin River generally contained higher body burdens of selenium when captured immediately below the mouth of North Mud Slough (3.1-4.8 ??g/g for green sunfish, 3.7-5.0 ??g/g for bluegills) than when captured upstream from the mouth (0.67-3.3 ??g/g for green sunfish, 0.59-3.7 ??g/g for bluegills). Waterborne selenium was the single most important predictor of selenium concentrations in green sunfish and bluegills, as judged by results from multiple-regression analyses. Among bluegills, water temperature also contributed to the prediction of selenium body burdens.

California↗
USGS1991

Preliminary assessment of the effects of selenium in agricultural drainage on fish in the San Joaquin Valley

Concentrations of total selenium were measured in whole-body samples of seven fishes from the Sacramento and San Joaquin River systems and the San Francisco Bay complex. Concentrations of selenium (up to 11 µ g/g dry weight in whole-body composite samples) were highest in fish from canals and sloughs in the Grassland Water District (Grasslands) that received large inflows of subsurface agricultural drainage water. Slightly lower selenium concentrations occurred in fish from the San Joaquin River immediately downstream from tributaries draining the Grasslands. Although circumstantial evidence suggests that selenium-sensitive species such as bluegills and largemouth bass are being excluded from the Grasslands, conclusive evidence of selenium toxicity is still lacking. In response to earlier reports of high concentrations of selenium in several species collected from the Grasslands, the California Department of Health Services has urged people to limit consumption of fish from this region.

Book chapter↗
USGS1986

Embryonic mortality and abnormalities of aquatic birds: Apparent impacts of selenium from irrigation drainwater

Severe reproductive impacts were found in aquatic birds nesting on irrigation drainwater ponds in the San Joaquin Valley of California. Of 347 nests studied to late incubation or to hatching, 40.6% had at least one dead embryo and 19.6% had at least one embryo or chick with an obvious external anomaly. The deformities were often multiple and included missing or abnormal eyes, beaks, wings, legs and feet. Brain, heart, liver and skeletal anomalies were also present. Mean selenium concentrations in plants, invertebrates, and fish from the ponds were 22–175 ppm (dry weight), about 12 to 130 times those found at a nearby control area. Bird eggs (2.2–110 ppm) and livers (19–130 ppm) also contained elevated levels of selenium. Aquatic birds may experience similar problems in other areas where selenium occurs at elevated levels.

California↗
USGS1985

Population biology of bluegills, Lepomis macrochirus, in lotic habitats on the irrigated San Joaquin Valley floor

Rapid expansion of irrigated agriculture in the western United States has prompted concerns for aquatic resources. Although the impacts of irrigation activities on quality and quantity of river water are well documented (e.g., high turbidity from soil erosion, eutrophication from nutrient runoff, pesticide contamination, reduced dis- charge), their effects on fish populations are still poorly understood. We studied the food, growth, and relative weight (a measure of body condition) of bluegills, Lepo- mis macrochirus, in relation to environmental factors in reaches of the San Joaquin and Merced rivers that have been affected to varying degrees by irrigation return flows. Fry of bluegills ate mostly cladocerans and copepods; fingerlings and larger fish ate immature aquatic insects, terrestrial insects, amphipods, and mollusks. Bluegill stomachs were fuller and contained a higher diversity of forage taxa in habitats with low turbidity and conductivity, weak buffering capacity, and low nutrient levels; bluegills also ate a more diverse diet where the potential forage supply (benthic macroinvertebrates) was most diverse. Bluegills attained mean total lengths of about 42 mm at age I, 86 mm at age 11, 116 mm at age III, 153 mm at age IV, and 166 mm at age V. Mean relative weight ranged from 96-111. Growth rate and relative weight were not significantly correlated with environmental or dietary variables. On the basis of our study, we concluded that environmental degradation from irrigation activities affected the diet of bluegills primarily by modifying the food supply, but growth rate and body condition were not affected.

California↗