27 research outputs found
Observations of the biological communities at Bolsa Chica artificial reef
Bolsa Chica Artificial Reef (BCAR) was constructed in
November 1986 with 10,400 tons of concrete rubble and
eight concrete and steel barges. Prior to any additional
augmentation of BCAR, the u.s. Army Corps of Engineers
and the California Coastal Commission required the
California Department of Fish and Game (CDFG) to survey
the bioloqical communities on and around BCAR.
In April 1992, qualitative surveys of the biological
communities were conducted on one of the eight modules at
BCAR and at a nearby sand-only site. One of the modules,
Module D, located in 90 feet of water (MLLW), was
surveyed for fish, macroinvertebrates, and turf community
organisms (small plants and sessile animals). Twelve
species of fish were observed, including kelp bass
(Paralabrax clathratus) and barred sand bass (P.
nebulifer). Eight macroinvertebrate species were
observed, rock scallops (Crassedoma giganteum) being the
most abundant. The turf community was comprised of
thirteen invertebrate taxa, among which erect ectoprocts
(Bugula spp.) were the most numerous. Two species of
foliose red algae (Rhodymenia pacifica and Anisocladella
pacifica) were also observed.
The reef has reached an advanced stage of successional
development with fish and invertebrate communities
diverse and well established. However, due,.to its depth
and the turbidity of surrounding waters, this reef is not
likely to ever support a diverse algal community.
The diversity and abundance of fish and
macroinvertebrates were, as to be expected, much lower in
the nearby sand-only site. Only two species of fish and
seven macroinvertebrate species were observed. Of these,
only the sea pen, Stylatula elongata, was common.
Overall, when compared to nearby sand-only habitats,
Bolsa Chica Artificial Reef appears to contribute
substantially to the local biological productivity. In
addition, the concrete rubble used in BCAR' s construction
appears to be performing as well as the quarry rock used
in all of CDFG's experimental reefs. (Document pdf contains 22 pages
Mathematical treatment of adiabatic fast passage pulses for the computation of nuclear spin relaxation rates in proteins with conformational exchange
Although originally designed for broadband inversion and decoupling in NMR spectroscopy, recent methodological developments have introduced adiabatic fast passage (AFP) pulses into the field of protein dynamics. AFP pulses employ a frequency sweep, and have not only superior inversion properties with respect to offset effects, but they are also easily implemented into a pulse sequence. As magnetization is dragged from the +z to the âz direction, Larmor precession is impeded since magnetization becomes spin-locked, which is a potentially useful feature for the investigation of microsecond to millisecond dynamics. A major drawback of these pulses as theoretical prediction is concerned, however, results from their time-dependent offset: simulations of spin density matrices under the influence of a time-dependent Hamiltonian with non-commuting elements are costly in terms of computational time, rendering data analysis impracticable. In this paper we suggest several ways to reduce the computational time without compromising accuracy with respect to effects such as cross-correlated relaxation and modulation of the chemical shift
Use of Genetic Stock Identification Data for Comparison of the Ocean Spatial Distribution, Size at Age, and Fishery Exposure of an Untagged Stock and Its Indicator: California Coastal versus Klamath River Chinook Salmon
Managing weak stocks in mixed-stock fisheries often relies on proxies derived from data-rich indicator stocks. For example, full cohort reconstruction of tagged Klamath River fall run Chinook salmon (Oncorhynchus tshawytscha) of northern California, USA, enables the use of detailed models to inform management. Information gained from this stock is also used in the management of the untagged, threatened California Coastal Chinook (CCC) salmon stock, by capping Klamath harvest rates. To evaluate use of this proxy, we used genetic stock identification (GSI) data to compare the two stocks\u27 size-at-age and ocean distribution, two key factors influencing fishery exposure. We developed methods to account for both sampling and genetic assignment uncertainty in catch estimates. We found that, in 2010, the stocks were similar in size-at-age early in the year (age-3 and age-4), but CCC fish were larger later in the year. The stocks appeared similarly distributed early in the year (2010), but more concentrated near their respective source rivers later in the year (2010 and 2011). If these results are representative, relative fishery impacts on the two stocks might scale similarly early in the year but management changes later in the year might have differing impacts on the two stocks
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Use of Genetic Stock Identification Data for Comparison of the Ocean Spatial Distribution, Size at Age, and Fishery Exposure of an Untagged Stock and Its Indicator: California Coastal versus Klamath River Chinook Salmon
Managing weak stocks in mixed-stock fisheries often relies on proxies derived from data-rich indicator stocks, although there have been limited tests of the appropriateness of such proxies. For example, full cohort reconstruction of tagged Klamath River fall-run Chinook Salmon Oncorhynchus tshawytscha of northern California enables the use of detailed models to inform management. Information gained from this stock is also used in the management of the untagged, threatened California Coastal Chinook Salmon (CCC) stock, where it is assumed that a cap on Klamath harvest rates effectively constrains impacts on CCC to acceptable levels. To evaluate use of this proxy, we used a novel approach based on genetic stock identification (GSI) data to compare the two stocksâ size at age and ocean distribution (as inferred from spatial variation in CPUE), two key factors influencing fishery exposure. We developed broadly applicable methods to account for both sampling and genetic assignment uncertainty in estimating total stock-specific catch from GSI data, and propagated this uncertainty into models quantifying variation in CPUE across space and time. We found that, in 2010, the stocks were similar in size at age early in the year (age 3 and age 4), but CCC fish were larger later in the year. The stocks appeared similarly distributed early in the year (2010) but more concentrated near their respective source rivers later in the year (2010 and 2011). If these results are representative, relative fishery impacts on the two stocks might scale similarly early in the year, but management changes later in the year could have differing impacts on the two stocks. This novel modeling approach is suited to evaluating the concordance between other data-limited stocks and their proxies, and can be broadly applied to estimate stock-specific harvest, and the uncertainty therein, using GSI in other systems
Stability in reproductive timing and habitat usage of Chinook salmon across six years of varying environmental conditions and abundance
Stock Composition and Ocean Spatial Distribution Inference from California Recreational Chinook Salmon Fisheries Using Genetic Stock Identification
We apply genetic stock identification (GSI) data and models of the catch and sampling process to describe spatial and temporal patterns in the stock composition and stock-specific catch-per unit-effort (CPUE) of both tagged and untagged stocks encountered in California recreational ocean Chinook salmon fisheries during the period 1998-2002. Spatial and temporal distributions inferred from GSI sampling of stocks with tagged hatchery components were broadly consistent with those previously inferred from studies of tag recoveries alone, while GSI provided additional insight into untagged stocks of conservation concern. The catch in all times and areas was dominated (typically â„90%) by the âCentral Valley Fallâ genetic reporting group, which is 64 comprised primarily of Sacramento River fall run Chinook. Other contributing stocks were more spread out in space and time with the exception of Central Valley winter run Chinook, which were rarely encountered by boats fishing in port areas north of Point Reyes. Localized stock specific CPUE appeared to increase near a stockâs respective natal river while decreasing in other port areas at the time of adult return to freshwater for spawning. We describe methods for quantifying uncertainty in stock proportions, stock-specific catch, and determining the statistical support for proposed management boundaries hypothesized to represent âbreak pointsâ in the spatial distributions for stocks of concern, and find at most equivocal support for a proposed delineation line at Point Reyes in north-central California
What caused the Sacramento River fall Chinook stock collapse? Pre-publication report to the Pacific Fishery Management Council
Adiposity and cancer risk: new mechanistic insights from epidemiology
Excess body adiposity, commonly expressed as body mass index (BMI), is a risk factor for many common adult cancers. Over the past decade, epidemiological data have shown that adiposity-cancer risk associations are specific for gender, site, geographical population, histological subtype and molecular phenotype. The biological mechanisms underpinning these associations are incompletely understood but need to take account of the specificities observed in epidemiology to better inform future prevention strategies