Scottish Association for Marine Science

About: Scottish Association for Marine Science is a facility organization based out in Oban, United Kingdom. It is known for research contribution in the topics: Sea ice & Benthic zone. The organization has 524 authors who have published 1765 publications receiving 70783 citations. The organization is also known as: SAMS & Scottish Marine Station for Scientific Research.

Synchronization in the molting and spawning activity of northern krill (Meganyctiphanes norvegica) and its effect on recruitment

Abstract: The molting, spawning, and recruitment of northern krill (Meganyctiphanes norvegica ) were analyzed over an annual cycle (1999‐2000) in the Clyde Sea (west coast of Scotland). Results supported the hypothesis of a functional relationship between egg production and molt development for the duration of the reproductive season (March to August), with one reproductive cycle being made up of two molt cycles. Females remained in reproductive condition throughout the reproductive season, and the timing of their spawning and molting was synchronized at the population level throughout this period. A semiempirical model predicted that the krill population produced an egg pulse every 20 to 26 d (depending on temperature), and three cohorts were evident in net samples taken later in the year. The likely date on which the first cohort was spawned was around 26 d after the main phytoplankton bloom, suggesting that the bloom triggered egg development in all adult females. Such a synchronized spawning period was observed directly in adult females 26 d after a bloom in March 2000. A total of three cohorts over the 6-month reproductive season is less than the maximum of seven that would be possible if spawning occurred at a periodicity of between 20 and 26 d, suggesting that larval recruitment was not always successful. Analysis showed that successful recruitment was only achieved when chlorophyll a levels were adequate during both the period of egg maturation in the ovary and the subsequent development of larvae, especially the furcilia stages. The reproductive cycles of euphausiids are known to be adapted to local conditions. The length and timing of the spawning season varies interspecifically, from the apparently continuous breeding of Euphausia hanseniin the subtropical Benguela upwelling system to the seasonally distinct breeding episodes of Euphausia superba in the Antarctic (Siegel 2000). Intraspecific variation is also evident in widely distributed species, such as northern krill ( Meganyctiphanes norvegica), that have short reproductive seasons in Mediterranean waters (e.g., the Ligurian Sea) but longer reproductive seasons in temperate boreal regions (e.g., the Clyde Sea and the Kattegat). A common pattern throughout the range of this species is the coincidence of reproductive scheduling with periods of optimal trophic conditions (Cuzin-Roudy and Buchholz 1999). The abundance of food items in boreal North Atlantic areas is generally high from early spring to late summer, facilitating a reproductive season that lasts from March to October. In the Mediterranean, the large blooms of

In vivo speciation studies and antioxidant properties of bromine in Laminaria digitata reinforce the significance of iodine accumulation for kelps

Abstract: The metabolism of bromine in marine brown algae remains poorly understood. This contrasts with the recent finding that the accumulation of iodide in the brown alga Laminaria serves the provision of an inorganic antioxidant - the first case documented from a living system. The aim of this study was to use an interdisciplinary array of techniques to study the chemical speciation, transformation, and function of bromine in Laminaria and to investigate the link between bromine and iodine metabolism, in particular in the antioxidant context. First, bromine and iodine levels in different Laminaria tissues were compared by inductively coupled plasma MS. Using in vivo X-ray absorption spectroscopy, it was found that, similarly to iodine, bromine is predominantly present in this alga in the form of bromide, albeit at lower concentrations, and that it shows similar behaviour upon oxidative stress. However, from a thermodynamic and kinetic standpoint, supported by in vitro and reconstituted in vivo assays, bromide is less suitable than iodide as an antioxidant against most reactive oxygen species except superoxide, possibly explaining why kelps prefer to accumulate iodide. This constitutes the first-ever study exploring the potential antioxidant function of bromide in a living system and other potential physiological roles. Given the tissue-specific differences observed in the content and speciation of bromine, it is concluded that the bromide uptake mechanism is different from the vanadium iodoperoxidase-mediated uptake of iodide in L. digitata and that its function is likely to be complementary to the iodide antioxidant system for detoxifying superoxide.

Evolution and distribution of TKE production and dissipation within stratified flow over topography

Abstract: [1] Analysis is presented of detailed observations of turbulence in stratified flow over topography. Key results are: 1) Directly measured dissipative energy losses due to skin friction and an internal hydraulic transition are relatively small, each accounting for approximately 10% of the mean flow energy loss, and 2) Production and dissipation of turbulent kinetic energy in flow over the topographic feature are in approximate balance throughout the transition from sub- to super-critical mean flow. The study is two-dimensional and a closed energy budget through direct measurement remains elusive; it is concluded that horizontal aspects of barotropic form drag such as eddy-shedding are responsible for as much as 30–40% of the mean flow energy loss.

Yield and physicochemical properties of EPS from Halomonas sp. strain TG39 identifies a role for protein and anionic residues (sulfate and phosphate) in emulsification of n-hexadecane.

Abstract: In this study, we investigated the yield and physicochemical properties of the high molecular weight extracellular polymeric substance (HMW-EPS) produced by Halomonas sp. strain TG39 when grown on different types and ratios of substrates. Glucose (1% w/v) and a peptone/yeast extract ratio of 5.1 (0.6% w/v final concentration) yielded an EPS fraction (HMW-glucose) exhibiting the highest anionic activity (20.5) and specific emulsifying activity (EI24 = 100%) compared to EPS produced by cells grown on mannitol, sucrose, malt extract or no carbon source. The HMW-EPS fractions were capable of binding approximately 255-464 mg of methylene blue (MB) per gram of EPS, which represents the highest reported binding of MB by a bacterial EPS. A comparative evaluation of these properties to those of commercial hydrocolloids indicated that the combined effect of protein and anionic residues of the HMW-EPS contributed to its ability to emulsify n-hexadecane. Liquid chromatography revealed the HMW-glucose EPS to be a heterogeneous polymer with a polydispersity index of 1.8. This work presents evidence of a correlation between the anionic nature and protein content of bacterial EPS with its emulsifying qualities, and identifies EPS produced by strain TG39 as a high MB-binding bacterial sorbant with potential biotechnological application.