Habitat and life history are critical elements in assessing the production dynamics of invertebrates and their role in aquatic ecosystems. We studied invertebrate productivity at two sites in a subtropical blackwater river (the Satilla) in the Lower Coastal Plain of Georgia, USA, and found that submerged wooden substrates, or snags, are heavily colonized by aquatic insects. We compared invertebrate productivity on the snag habitat with productivity in the sandy benthic habitat of the main channel, and the muddy benthic habitat of the backwaters. The size—frequency method was applied to individual taxa in order to determine total invertebrate productivity. Emphasis was placed on the importance of the length of larval life, or the cohort production interval, in determining biomass turnover rates. The diversity of taxa was much higher on the snag habitat than in either of the benthic habitats. Filter—feeding caddisflies (especially Hydropsyche spp.) and black flies (Simulium spp.) were the major consumers on the snag habitat. Several species of midges, mayflies, and beetles also were abundant. Total densities, standing stock biomass, and production were very high for primary consumers on snags. Annual production was 51.9 and 67.1 g°m—2°yr—1 (dry mass per surface area of snag, or effective habitat) for the two sites. Hellgrammites, dragonflies, and stoneflies were the major insect predators colonizing snags, and their production was 5.5 and 5.2 g@mm—2°yr—1 (effective habitat). Annual production/biomass ratios (P/B) were usually 5—10 for insects that had univoltine or bivoltine life cycles. Annual P/B estimates were very high for midges (>100) and black flies (>70), since length of larval life was estimated to be very short. The sandy—substrate benthos consisted almost exclusively of very small midges with oligochaetes of lesser abundance. Densities were quite high (>20 000/m2), but biomass was very low (° 100 mg/m2 or less). Production of primary consumers was >11 g°m—2°yr—1 with a very high estimate of annual P/B (166—227). The major predators were Ceratopogonidae (biting midges) larvae with an annual production of 1.6—2.6 g°m—2°yr—1. The muddy—substrate benthos consisted primarily of oligochaetes (Limnodrilus) and midges. Annual production was °7—10 g°m—2°yr—1 for primary consumers. The major predators were larger Tanypodinae midges. On a substrate surface area basis, standing stock biomass on snags was 20—50 times higher than in the sandy habitat and 5—10 times higher than in the muddy habitat. Production on snags was only 3—4 times higher than production in the benthic habitats, with higher annual P/B in the latter. The production estimates for the snag habitat are among the highest yet reported for lotic ecosystems, and it appears that production on snags is limited by available substrate. Habitat areas per length of shoreline were estimated so that we could approximate relative amounts of biomass and production for a stretch of river. Although the snag habitat accounted for only °6% of the effective habitat subs...

Consumption of tomato products has been associated with decreased risk of some cancer types, and the tomato antioxidant, lycopene, is thought to play an important role in the observed health effects. In this study, four carotenoids, trans-lycopene, phytofluene, phytoene, and zeta-carotene, were quantified in tomato products. Samples of raw tomatoes, tomato juice after hot break scalder, and final paste were obtained from two different processing plants over two years. Comparison of carotenoid levels throughout processing indicated that lycopene losses during processing of tomatoes into final paste (25-30 degrees Brix) ranged from 9 to 28%. The initial Brix level of the raw tomatoes appeared to influence the amount of lycopene loss that occurred, possibly due to the differences in processing time required to achieve the final desired Brix level of the paste. In general, no consistent changes in the other carotenoids were observed as a function of processing. The antioxidant activity of fresh tomatoes, tomato paste, and three fractions obtained from these products (i.e., aqueous, methanol, and hexane fractions) was also determined. In both a free radical quenching assay and a singlet oxygen quenching assay, significant antioxidant activity was found in both the hexane fraction (containing lycopene) and the methanol fraction, which contained the phenolic antioxidants caffeic and chlorogenic acid. The results suggest that in addition to lycopene, polyphenols in tomatoes may also be important in conferring protective antioxidative effects.

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The annual production by phytoplankton in the southern basin of the Great Salt Lake as estimated at two stations in 1973 averaged 145 g C mm2. The majority of the production occurred during March and April and was due to an unidentified species of Dunaliellu. Daily carbon fixation rates averaged 2.13 g C mm2 at both locations during this period. A minor phytoplankton bloom in August, due to a small, unidentified green flagellate contributed 5% of the total annual phytoplankton production. Phytoplankton production was probably limited during April by self-shading and during the remainder of the year by the availability of nitrogen, as shown by laboratory bioassays. Crazing by Artemia dina reduces the phytoplankton population in late summer when nutrient levels have partially increased due to regeneration. The meromictic character of the lake was indicated by profiles of temperature and density. The monimolimnion is postulated to act as a nutrient sink, reducing the rate of nutrient release to the mixolimnion.