Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel,Australia

Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29tCha–1yr–1. This equates to about 204,000tCyr–1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.     

Numbers of nesting frigatebirds, Fregata minor and F. ariel, on Aldabra Atoll nature reserve,Seychelles

Aldabra Atoll, a strict Nature Reserve and major breeding station of lesser and greater frigatebirds, may be developed for tourism. Determining whether this affects the frigate breeding populations is complicated by their extended annual laying seasons and the biennial breeding periodicity of individuals rearing fledgelings. This study, using a census method incorporating adjustments for seasonal changes in nest numbers, changes in nest ownership and replacement laying, indicates that there are at least 4000 pairs of greater frigatebirds and 6000 pairs of lesser frigatebirds annually involved in breeding activities. There is some evidence that more male than female greater frigatebirds attempt to pair each season. Comparison with an earlier census suggests that severe human disturbance induces curtailment of laying seasons, major changes in nest distribution and prevents many birds from breeding.     

Size, stability, and entrapment efficiency of phospholipid nanocapsules containing polypeptide antimicrobials

The effect of lipid composition [phosphatidylcholine (PC), phosphatidylglycerol (PG), and cholesterol] on size, stability, and entrapment efficiency of polypeptide antimicrobials in liposomal nanocapsules was investigated. PC, PC/cholesterol (70:30), and PC/PG/cholesterol (50:20:30) liposomes had entrapment efficiencies with calcein of 71, 57, and 54% with particle sizes of 85, 133, and 145 nm, respectively. Co-encapsulation of calcein and nisin resulted in entrapment efficiencies of 63, 54, and 59% with particle sizes of 144, 223, and 167 nm for PC, PC/cholesterol (70:30), and PC/PG/cholesterol (50:20:30), respectively. Co-encapsulation of calcein and lysozyme yielded entrapment efficiencies of 61, 60, and 61% with particle sizes of 161, 162, and 174 nm, respectively. The highest concentration of antimicrobials was encapsulated in 100% PC liposomes. Nisin induced more calcein release compared to lysozyme. Results demonstrate that production and optimization of stable nanoparticulate aqueous dispersions of polypeptide antimicrobials for microbiological stabilization of food products depend on selection of suitable lipid-antimicrobial combinations.     

Production Management of Double-Net Tilapia Oreochromis spp. Hatcheries in a Eutrophic Tropical Reservoir

Abstract.— A floating, double-net hatchery system for a red tilapia hybrid Oreochromis spp. was developed and tested in a eutrophic reservoir in West Java, Indonesia. Objectives of the studies were to test the effects of different male and female broodstock rotation times on fingerling production and compare production of the double-net system with other studies using a multiple regression model. Two experiments (EXP1 and EXP2) were conducted in four separate double-net hatchery systems comparing three broodstock rotation times over 12 spawning periods in EXP1 and 21 in EXP2. In both experiments, shorter broodstock rotation times (14–16 d in EXP1 or 10–15 d in EXP2) produced significantly ( P < 0.05) higher numbers of fingerlings (6.24 in EXP1 and 14.52 fingerlings/female per d in EXP2). A multiple regression model was developed to summarize results of six studies which included 31 spawning periods. A significant ( r² = 0.651, P < 0.05) relationship was found between tilapia seed production in net hatcheries as the dependent variable and initial female broodstock densities (−), initial female body weight (−), female/male stocking ratio (−), and feed protein content (±) as independent variables.     

Growth and its partitioning in Prunus rootstocks in response to root zone temperature

Rootstocks for stone fruit varieties differentially influence tree physiology and one possible explanation for these differences is that varieties vary in their response to root zone temperature (RZT). To examine the effects of RZT, two trials using actively growing plants of five different Prunus rootstocks with chill requirements between 100 and 1100 h were undertaken. Plants were grown at RZTs of 5, 13 and 19 °C for 6 weeks after which total dry matter accumulation and its partitioning amongst roots, stems and leaves was determined. In general, the magnitude of total dry matter and its component parts positively correlated with RZT and significant differences were found among varieties in the magnitude of total dry matter accumulation. Individual varieties ranked differently at the three RZTs with respect to total dry matter: in general, the same ranking was also seen in the ranking of each growth component. RZT significantly influenced partitioning causing differences in leaf, stem and root mass ratios. These differences were greatest at low RZTs and became less as RZT increased. Several patterns of partitioning were found. Firstly, the low chill varieties (Okinawa and Flordagold) were little affected by RZT with similar partitioning occurring at each RZT. Secondly, the higher chill varieties, Green Leaf Nemaguard (GL), Golden Queen (GQ) and Fay Elberta (FE), reacted more strongly to RZT and were particularly affected by the lowest RZT. For these varieties, the root mass ratio rose and stem mass ratio fell as RZT increased. However, with respect to leaf mass ratio, two different trends were found: the leaf mass ratio for FE and GQ positively correlated with RZT whilst the relationship for GL was negative. These findings suggest that the response to RZT is related to a variety's chill requirement; offer an explanation for differences in performance of rootstock–scion combinations at different locations; and will aid the development of more accurate tree performance models by taking RZT into account.