Search

Low feed intake has been considered a major problem in applying formulated feed for grow-out of spiny lobster (Panulirus homarus). This study was conducted to evaluate the effects of fishery hydrolysate in feed formulation and the co-feeding of formulated feed with fresh food on the feed intake of spiny lobster. Five experiments of feed intake assessment were conducted using either different sources (tuna, crustacean and mussel) or levels (0%, 1%, 2% and 3%) of hydrolysates, and experiments on different feeding schemes where lobsters fed either only formulated feed or formulated feed and fresh food. Each experiment was performed for 2 weeks using 16 fiberglass tanks (300 L) filled with seawater and each experiment has 4 treatments with 4 replicates. The experiment showed that including fish hydrolysate 2%, crustacean hydrolysate 1% (dry) or 2% (liquid), or 2 % tuna hydrolysate in feed increased the feed intake of spiny lobster. Feed intake of formulated feed decreased when they fed in combination with mixed fresh food. Feed intake of lobster fed mixed fresh food was lower than that fed either mussel or crab only, and lobster fed only fish exhibited the lowest feed intake.

RATIONALE:Sulfur isotope ratio measurements of bulk sulfide from marine sediments have often been used to reconstruct environmental conditions associated with their formation. In situ microscale spot analyses by secondary ion mass spectrometry (SIMS) and laser ablation multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) have been utilized for the same purpose. However, these techniques are often not suitable for studying small (≤10 μm) grains or for detecting intra-grain variability. METHODS:Here, we present a method for the physical extraction (using lithium polytungstate heavy liquid) and subsequent sulfur isotope analysis (using SIMS; CAMECA IMS 7f-GEO) of microcrystalline iron sulfides. SIMS sulfur isotope ratio measurements were made via Cs+ bombardment of raster squares with sides of 20-130 μm, using an electron multiplier (EM) detector to collect counts of 32 S- and 34 S- for each pixel (128 × 128 pixel grids) for between 20 and 960 cycles. RESULTS:The extraction procedure did not discernibly alter pyrite grain-size distributions. The apparent inter-grain variability in 34 S/32 S in 1-4 μm-sized pyrite and marcasite fragments from isotopically homogeneous hydrothermal crystals was ~ ±2‰ (1σ), comparable with the standard error of the mean for individual measurements (≤ ±2‰, 1σ). In contrast, grain-specific 34 S/32 S ratios in modern and ancient sedimentary pyrites and marcasites can have inter- and intra-grain variability >60‰. The distributions of intra-sample isotopic variability are consistent with bulk 34 S/32 S values. CONCLUSIONS:SIMS analyses of isolated iron sulfide grains yielded distributions that are isotopically representative of bulk 34 S/32 S values. Populations of iron sulfide grains from sedimentary samples record the evolution of the S-isotopic composition of pore water sulfide in their S-isotopic compositions. These data allow past local environmental conditions to be inferred.

Isotope geochemistry requires isotope ratios measured using secondary ion mass spectrometry (SIMS) to be made with optimal precision and accuracy. Under some analytical conditions when using electron multiplier detectors, secondary ions may be under‐counted because of quasi‐simultaneous arrival (QSA) at the first dynode. The relative magnitude of the associated QSA correction to raw measured isotopic ratios can be up to seventy permil or more. Therefore, not applying the correction, or misapplication of it could lead to significant inaccuracies in published isotope ratio data. Examples and ramifications of the latter are described in addition to a straightforward procedure for QSA under‐counting correction. [ABSTRACT FROM AUTHOR]

The study aimed to assess lobster fry adaptation to a formulated diet over 1-3 days while evaluating the recirculating system's performance. 1,500 pueruli lobsters (average weight: 0.31 ± 0.01 g) were placed in 30 round 80 L tanks for 30 days. Lobsters underwent various feeding strategies: formulated diet only (FD), adjusting 10% fresh diet per day (D1), every 2 days (D2), every 3 days (D3), and fresh diet only (Fr). Each treatment had five replicates. Results showed feeding strategies influenced lobster growth, with survival rates between 23%-29%. The recommended strategy was adjusting 10% fresh diet every three days, yielding the best performance in final weight (0.93 g), weight gain (187%), and specific growth rate (3.5% per day). Initial weeks saw high mortality and moulting during the puerulus to post-puerulus transition. Water quality analysis indicated the phytobiological filter had lower total ammonia nitrogen (TAN), nitrite-N, nitrate-N, and higher pH compared to other filters in use.