ABSTRACT. From 1989 to 1990, we studied a previously undescribed mussel Modiolus americanus (Leach) habitat (with densities as high as 2000 ind. m-2) within the seagrass meadows of St. Joseph Bay, Florida, USA. Using suction sampling, we compared macroinvertebrate abundance, biomass, and annual production estimates in mussel habitat with 3 other habitats: monotypic stands of Thalassia testudinum (Banks ex Konig), Halodule wrightii Aschers and unvegetated sand flats. Previous studies have positively correlated macrofaunal densities and species number with measures of vegetation abundance or architecture. This relationship was not found to be strong in our study. Macroinvertebrate abundance, biomass, and annual production were usually equivalent or higher in mussel than in the other 3 habitats despite aboveground seagrass biomass usually being intermediate between pure stands of T testudinum and H. wrightii, and leaf surface area lowest. Of particular interest was annual macroinvertebrate production whlch ranged from 228.77 to 428.59 g ash-free dry mass (AFDW) m-2 in mussel habitat, followed in descending order by pure stands of T. testudinum (144.90 to 245.44 g AFDW m-'), H. wrightii (83.98 to 180.44 g AFDW m-2), and sand flats (19.83 to 42.47 g AFDW m-').These production estimates illustrate the positive effect that mussels can have in elevating already high levels of macroinvertebrate production in seagrass meadows.

A modified ASTM F 739-85 test method has been developed which permits the collection and analysis of both volatile and non-volatile, low aqueous solubility compounds from mixtures which permeate protective clothing materials. Permeation tests have been conducted using eleven pesticide formulations containing a range of active ingredient and carrier solvent types and concentrations. Nitrile, natural rubber, and neoprene glove materials were tested in every case; PVC., polyethylene and butyl glove materials were examined in selected instances. Both carrier solvent and active ingredient permeation were measured over the eight-hour test period. Carrier solvent concentration was found to have the most effect on the permeation resistance of glove materials. Xylene range aromatic solvents were most dramatic in decreasing the breakthrough times of both carrier solvent and active ingredient and in increasing the cumulative amounts of permeants measured.