Grow-out mariculture techniques in tropical waters: a case study of problems and solutions in Hong Kong

Raft culture is practised and trash fish is being used as feed in Hong Kong. Culture space is limited and most of the culture sites are over-crowded. Food conversion ratio is poor (about 10-15), grow-out mortality is high (30-50%) and fish kills caused by oxygen depletions, algal blooms and red tides occur frequently. Disease and water pollution are also problems

Field validation, in Scotland and Iceland, of the artificial mussel for monitoring trace metals in temperate seas

The artificial mussel (AM), a novel chemical sampling device, has been developed for monitoring dissolved trace metals in marine environments. The AM consists of Chelex-100 suspended in artificial seawater within Perspex tubing and enclosed with semi-permeable polyacrylamide gel at both ends. To validate the field performance of the AM in temperate waters, we deployed AMs alongside transplanted blue mussels Mytilus edulis in coastal environments in Scotland (Holy Loch, Loch Fyne, Loch Striven and Millport) and Iceland (Reykjavikurhofn, Gufunes, South of [thorn]erney, Hofsvik, Hvalfjorethur and Sandgerethi) for monitoring trace metals. While uptake patterns of Cd between the AM and M. edulis were highly comparable, discrepancies were found in the accumulation profiles of the other metals (Cu, Cr, Pb and Zn), in particular Zn. Nonetheless, the AMs gave a better resolution to accurately reveal the spatial difference in dissolved metal contamination when compared with M. edulis. AMs complement the use of mussels since AMs indicate dissolved metals in seawater, whereas uptake by mussels indicates a mixture of dissolved and particulate metals. Our results also indicated that historical metal exposure of the transplanted M. edulis could significantly confound their metal concentrations especially when the deployment period was short (i.e. lt 34 d). This study suggested that the AM can overcome problems associated with variable biological attributes and pre-exposure history in the mussel, and provides a standardized and representative time-integrated estimate of dissolved metal concentrations in different marine environment

The sleeper Bostrichthys sinensis (Family eleotridae) stores glutamine and reduces ammonia production during aerial exposure

10.1007/s003600100184Journal of Comparative Physiology - B Biochemical, Systemic, and Environmental Physiology1715357-367JCPB

Metabolic adjustments in the common carp during prolonged hypoxia

10.1006/jfbi.2000.1382Journal of Fish Biology5751160-1171JFIB

Growth rate as a factor confounding the use of the dogwhelk <i>Nucella lapillus </i>as biomonitor of heavy metal contamination

Growth rate of individually tagged dogwhelks Nucella lapillus (L.) was measured in free-living individuals at 3 sites of differing heavy metal contamination in the Firth of Clyde, west Scotland. Condition index (CI), concentrations of metals (Cd, Cu, Pb and Zn), metallothionein (NIT), RNA (the RNA/protein ratio) and glycogen were also measured. In general, the marine environments of Gourock and Largs were contaminated with significantly higher tributyltin, Pb and Zn than Loch Fyne, as indicated by the results of imposex indices, and metal concentrations in transplanted polymer-ligands (Chelex (R) 100) and Mytilus edulis. Further, metal concentrations of native M. edulis (Pb and Zn) and Semibalanus balanoides (Cu) from Gourock were significantly higher than those from Loch Fyne. However, metal accumulation in the dogwhelks displayed a very different pattern. At a standard size (0.5 g wet soft-body weight), N. lapillus from Largs showed higher Cd, Cu and MT in their tissues than individuals from the other 2 populations. Levels of Pb and Zn were similar among the populations despite different concentrations in Chelex and mussels. Gourock dogwhelks showed similar levels of Cu and NIT but lower Cd compared to those of Loch Fyne. These differences can be attributed primarily to differences in dogwhelk growth rate between sites. Gourock individuals had a higher Cl and RNA/protein ratio in the foot muscle and grew faster (especially at small sizes), resulting in a tissue-dilution effect on metal and NIT concentrations, In contrast, higher levels of Cd, Cu and NIT in dogwhelks from Largs can be attributed to their growth rate being relatively slow compared to the rate of metal accumulation, Slow-growing individuals in Loch Fyne had relatively high Cd, Pb Zn and NIT, although Loch Fyne has been regarded as a clean reference site, Among populations, differences in growth rate may be due to differences in prey availability, predation pressure, and/or genotype. The present results demonstrate that inter-site differences in growth rate can confound the use of the dogwhelks as a biomonitor of metal

Seasonal variation of macrobenthic infauna in the Johor Strait, Singapore

10.1007/s10452-004-7111-2Aquatic Ecology391-2107-111AQEC