Survival and changes in the fine structure of selected tissues of Penaeus monodon Fabricius juveniles fed various carbohydrates

Penaeus monodon juveniles were reared on semipurified diets containing various carbohydrates (maltose, sucrose, dextrin, molasses, cassava starch, corn starch or sago palm starch). Significant differences were observed between the type as well as the level of carbohydrate in the diet on the survival of the juveniles. Results indicate that there does not seem to be any correlation between survival and the complexity of the carbohydrates.

Determination of population structure and stock composition of chum salmon (Oncorhynchus keta) in Russia determined with microsatellites

Variation at 14 microsatellite loci was examined in 34 chum salmon (Oncorhynchus keta) populations from Russia and evaluated for its use in the determination of population structure and stock composition in simulated mixed-stock fishery samples. The genetic differentiation index (Fst) over all populations and loci was 0.017, and individual locus values ranged from 0.003 to 0.054. Regional population structure was observed, and populations from Primorye, Sakhalin Island, and northeast Russia were the most distinct. Microsatellite variation provided evidence of a more fine-scale population structure than those that had previously been demonstrated with other genetic-based markers. Analysis of simulated mixed-stock samples indicated that accurate and precise regional estimates of stock composition were produced when the microsatellites were used to estimate stock compositions. Microsatellites can be used to determine stock composition in geographically separate Russian coastal chum salmon fisheries and provide a greater resolution of stock composition and population structure than that previously provided with other techniques.

Sediment Quality Triad assessment in Kachemak Bay: characterization of soft bottom benthic habitats and contaminant bioeffects assessment

A baseline environmental characterization of the inner Kachemak Bay, Alaska was conducted using the sediment quality triad approach based on sediment chemistry, sediment toxicity, and benthic invertebrate community structure. The study area was subdivided into 5 strata based on geophysical and hydrodynamic patterns in the bay (eastern and western intertidal mud flats, eastern and western subtidal, and Homer Harbor). Three to seven locations were synoptically sampled within each stratum using a stratified random statistical design approach. Three sites near the village of Port Graham and two sites in the footprint of a proposed Homer Harbor expansion were also collected for comparison. Concentrations of over 120 organic and metallic contaminants were analyzed. Ambient toxicity was assessed using two amphipod bioassays. A detailed benthic community condition assessment was performed. Habitat parameters (depth, salinity, temperature, dissolved oxygen, sediment grain size, and organic carbon content) that influence species and contaminant distribution were also measured at each sampling site. Sediments were mostly mixed silt and sand; characteristic of high energy habitats, with pockets of muddy zones. Organic compounds (PAHs, DDTs, PCBs, cyclodienes, cyclohexanes) were detected throughout the bay but at relatively low concentrations. Tributyltin was elevated in Homer Harbor relative to the other strata. With a few exceptions, metals concentrations were relatively low and probably reflect the input of glacial runoff. Relative to other sites, Homer Harbor sites were shown to have elevated concentrations of metallic and organic contaminants. The Homer Harbor stratum however, is a deep, low energy depositional environment with fine grained sediment. Concentrations of organic contaminants measured were five to ten times higher in the harbor sites than in the open bay sites. Concentration of PAHs is of a particular interest because of the legacy of oil spills in the region. There was no evidence of residual PAHs attributable to oil spills, outside of local input, beyond the confines of the harbor. Concentrations were one to ten times below NOAA sediment quality guidelines. Selected metal concentrations were found to be relatively elevated compared to other data collected in the region. However, levels are still very low in the scale of NOAA’s sediment quality guidelines, and therefore appear to pose little or no ecotoxicity threat to biota. Infaunal assessment showed a diverse assemblage with more than 240 taxa recorded and abundances greater than 3,000 animals m-22 in all but a few locations. Annelid worms, crustaceans, snails, and clams were the dominant taxa accounting for 63 %, 19%, 5%, and 7 % respectively of total individuals. Specific benthic community assemblages were identified that were distributed based on depth and water clarity. Species richness and diversity was lower in the eastern end of the bay in the vicinity of the Fox River input. Abundance was also generally lower in the eastern portion of the study area, and in the intertidal areas near Homer. The eastern portions of the bay are stressed by the sediment load from glacial meltwater. Significant toxicity was virtually absent. Conditions at the sites immediately outside the existing Homer Harbor facility did not differ significantly from other subtidal locations in the open Kachemak Bay. The benthic fauna at Port Graham contained a significant number of species not found in Kachemak Bay. Contaminant conditions were variable depending on specific location. Selected metal concentrations were elevated at Port Graham and some were lower relative to Kachemak Bay, probably due to local geology. Some organic contaminants were accumulating at a depositional site.