Coastal ecosystems are estimated to support 95% of the world's commercially-important fish, owing largely to their provision of nursery habitat for juveniles; however, systematic databases with such data are scarce. By systematically reviewing the literature across Australia, we quantified fisheries enhancement from three key coastal vegetated habitats: seagrass meadows, mangrove forests, and tidal marshes. From juvenile densities, we modelled adult fish biomass enhancement resulting from these structured habitats and linked fish of economic importance with market values. We found that seagrass displayed higher per hectare abundance, biomass and economic enhancement compared to mangroves and tidal marshes. On average, one hectare of seagrass supported 55,000 more fish annually compared to unvegetated seabed, resulting in an additional biomass of 4,000 kg and a value increase of AUD 21,200 annually. Mangroves supported 19,000 more fish, equivalent to 265 kg -1 ha -1 y -1 , and tidal marshes provided a modest 1,700 more fish, equivalent to 64 kg -1 ha -1 y -1 . The most abundant fish across all ecosystems were small, non-commercial species (e.g. gobies and glassfish), but the highest biomass and economic value originated from larger, longer-lived fish that are regularly targeted by fisheries (e.g. breams and mullets). By quantifying enhancement value across Australia, our findings provide further evidence for, the benefit these critical habitats provide in supporting coastal fisheries and human well-being.

A membrane is defined as a solid, porous sheet which, when placed between two phases, may allow the passage of small particles but hinder or prevent the passage of large particles. With this definition as a basis a review is given of methods employed to prepare membranes, with special emphasis on the preparation of organic membranes. Directions are then given for the preparation of thin, uniform membranes 100 to 1500 A. or thicker. Membranes of 500 or 600 A., in thickness with a variation of less than 25 A. across a section as large as 3.5 cm. sq. are described, together with evidence for physical and chemical stability. These are prepared from pyroxylin. Thin membranes were also prepared from Formvar 15/95 E (polyvinylformal from Shawinigan Resins Corp.) and VYDR, blend 7 (a high molecular weight vinylchloride‐acetate resin containing approximately 96% vinylchloride and 4% vinylacetate, from Bakelite). No success was achieved with DYNH (a polythylene from Bakelite); and polyisobutylmethacrylate (Monomer‐Polymer).

Michigan synopsisRefined techniques and a simple apparatus for producing thin (300-1300 A.) polymer films on glass slides from appropriate polymer solutions are described. A film thickness reproducibility of f25A. can be achieved without difEculty. The polymers investigated included Formvar 15/19E, Parlodion, VYDR blend B-7, and Cyanocel. Data are p r e sented which show the effect on film thickness of a drain period for the glass slide just above the polymer solution, the residence time of the glaea slide in the polymer solution, the nature of the solvent, the concentration of the polymer solution, the temperature, and the nature of the polymer. The results show that the reproducibility of polymer film thickness and the uniformity of the films is higher as the thickness of the film decreases (below about lo00 A.). Film casting conditions which favor a rapid departure of the solvent from the polymer film (such as elevated temperature, dilute solutions, and solvents of high volatility) yielded a high reproducibility in 6lm thickness and an excellent film uniformity.

No abstract

SynopsisThe membrane potentials of thin (300-1300 A.) nitrocellulose (Parlodion) membranes have been investigated. Measurements were made in a Lucite cell by use of calomel electrodes with 0.05N KC1 and 0.1N KC1. Variables having an influence on membrane structure, such as solvent polarity, temperature, and thickness, have been studied in relation to membrane potential. The range of potentials observed for Parlodion (2.1-9.2 mv.) is believed to be the result of differences in the orientation of the nitrocellulose molecules (and their accompanying electrochemically active carboxyl groups) in the membrane structure.