Topic
Neomysis
About: Neomysis is a research topic. Over the lifetime, 101 publications have been published within this topic receiving 2963 citations.
Papers published on a yearly basis
Papers
TL;DR: It is concluded that predation pressure on zooplankton is higher and algal grazing capacity lower in brackish eutrophic-hypertrophic lakes than in comparable freshwater lakes, and that the differences in trophic structure ofBrackish and freshwater lakes have major implications for the measures available to reduce the recovery period following a reduction in nutrient loading.
Abstract: The effects of nutrients on the biological structure of brackish and freshwater lakes were compared. Quantitative analysis of late summer fish, zooplankton, mysid and macrophyte populations was undertaken in 20–36 shallow brackish lakes of various trophic states and the findings compared with a similar analysis of shallow freshwater lakes based on either sampling (fish) or existing data (zooplankton, mysids and macrophytes). Special emphasis was placed on differences in pelagic top-down control. Whereas the fish biomass (CPUE, multiple mesh-size gill nets) rose with increasing P-concentration in freshwater lakes, that of brackish lakes was markedly reduced at P-concentrations above ca. 0.4 mg P 1−1 and there was a concomitant shift to exclusive dominance by the small sticklebacks (Gasterosteus aculeatus and Pungitius pungitius); as a result, fish density remained relatively high. Mysids (Neomysis integer) were found at a salinity greater than 0.5‰ and increased substantially with increasing P-concentration, reaching levels as high as 13 ind. 1−1. This is in contrast to the carnivorous zooplankton of freshwater lakes, which are most abundant at intermediate P levels. The efficient algal controller, Daphnia was only found at a salinity below 2‰ and N. integer in lakes with a salinity above 0.5‰. Above 2‰ the filter-feeding zooplankton were usually dominated by the less efficient algal controllers Eurytemora and Acartia. In contrast to freshwater lakes, no shift to a clearwatex state was found in eutrophic brackish lakes when submerged macrophytes became abundant. We conclude that predation pressure on zooplankton is higher and algal grazing capacity lower in brackish eutrophic-hypertrophic lakes than in comparable freshwater lakes, and that the differences in trophic structure of brackish and freshwater lakes have major implications for the measures available to reduce the recovery period following a reduction in nutrient loading. From the point of view of top-down control, the salinity threshold dividing freshwater and brackish lakes is much lower than the conventionally defined 5‰.
222 citations
TL;DR: The only British representative of Neomysis Czerniavsky is N. integer (Leach), which lives in estuarine, brackish-water situations.
Abstract: INTRODUCTIONThere are more than twenty species in the genus Neomysis Czerniavsky, of which the only British representative is N. integer (Leach). This is one of the commonest species of mysids round the coasts of Britain. It lives in estuarine, brackish-water situations and Tattersall & Tattersall (1951) have summarized its distribution. The present investiga- tion has added many records from the west coast lochs of Scotland: Lochs Striven, Riddon, Fyne, Gilp, Ranza in the Firth of Clyde; Lochs Craignish, Feochan, Etive, Creran, Shuna, Linnhe, Eil and Torridon farther north. The biology of Neomysis species is much better known than that of species in other genera:N. americana (Smith) has been studied by Cowles (1930), Whiteley (1948), Hulburt (1957) and Hopkins (1965); the biology of N. awatschensis (Brandt) has been examined by Ii (1964) and Turner & Heubach (1966), that of N. czerniawskii Derjavin and N. intermedia (Czerniavsky) by Ii (1964), that of N.japonica Nakazawa by Ishikawa & Oshima (1951) and Ii (1964), that of N. rayii (Murdoch) and N. spinosa Nakazawa by Ii (1964).
89 citations
TL;DR: The effects of temperature and diet on the specific growth rate and food consumption of 1-summer-old Arctic charr Salvelinus alpinus were studied and Charr seemed to compensate for the high water content of Neomysis by having a higher food intake.
Abstract: The effects of temperature and diet on the specific growth rate and food consumption of 1-summer-old Arctic charr Salvelinus alpinus were studied. Fish were reared singly in aquaria at six different constant temperatures (5, 9, 13, 16, 18 and 20°C). They were fed Neomysis integer or commercial pelleted food for 2 weeks and growth and food consumption were measured. In both experiments, growth rate increased to an optimum at 15°C. Growth rates were high in the range 13–18°C, with no significant (P >0·05) differences between temperatures. No significant (P> 0·05) differences in growth were found between fish at 9 and 20°C. There were no effects of diet on size-adjusted growth rates. The growth efficiency decreased with increasing temperature in both treatments, but the decrease was faster in the Neomysis treatment. Charr seemed to compensate for the high water content (79·5%) of Neomysis by having a higher food intake.
85 citations
TL;DR: The dominant members of the freshwater zooplankton in the Sacramento-San Joaquin delta were those typical of temperate zone rivers, such as Bosmina and Cyclops among crustaceans and Keratella, Polyarthra, Trichocerca and Synchaeta among rotifers.
Abstract: The dominant members of the freshwater zooplankton in the Sacramento-San Joaquin delta were those typical of temperate zone rivers—Bosmina andCyclops among the crustaceans andKeratella, Polyarthra, Trichocerca andSynchaeta among the rotifers. The estuarine or brackish component of the plankton was represented by the copepodEurytemora affinis and the rotiferSynchaeta bicornis. Abundace of freshwater zooplankton was highest in the San Joaquin River near Stockton, the region with the highest chlorophylla concentrations and highest temperatures. This was also the region least affected by water project operations, which alter the normal river flow patterns and bring large volumes of zooplankton-deficient Sacramento River water into the San Joaquin River and south delta chanels. Over a seven-year period, abundance of most zooplankton genera was positively correlated with chlorophylla concentrations and temperature but not with net flow velocity. OnlyBosmina had a significant and negative correlation with abundance of a predacious shrimp,Neomysis mercedis. Extreme salinity intrusion in 1977 reduced freshwater zooplankton abundance throughout most of the delta to seven-year lows. All zooplankton groups showed a long-term abundance decline from 1972 to 1978. In the cases of rotifers and copepods, this deciline was significantly correlated with a decline in chlorophylla.
84 citations
TL;DR: The rates of nitrogenous excretion in the form of ammonia, amino acids, urea, and total nitrogen are determined for Neomysis rayii and Euphausia pacifica at two temperatures, 10 and 4C.
Abstract: The rates of nitrogenous excretion in the form of ammonia, amino acids, urea, and total nitrogen are determined for Neomysis rayii and Euphausia pacifica at two temperatures, 10 and 4C. Temperature has a marked effect on the excretory rates. Ammonia-N is the dominant form of excretion in both species (72–87% of nitrogen excreted), and the amounts of amino nitrogen excreted by both organisms are much lower than reported by earlier authors for other zooplankton. There is evidence that amino-N is excreted below 6C. Small quantities of urea are excreted by Euphausia pacifica only.
Neomysis rayii excretes 25 µg N/mg body nitrogen per day at 10C and 15 µg N/mg body nitrogen per day at 4C. Euphausia pacifica excretes 21 µg N/mg body nitrogen per day at 10C and 12 µg at 4C. While starved, these species catabolize proteins almost exclusively and lose about 2% of body protein per day.
83 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2018 | 1 |
| 2017 | 4 |
| 2016 | 2 |
| 2015 | 2 |
| 2012 | 2 |