Respiratory electron transport system (ETS) activities in zooplankton and micronekton of the Indo-Pacific region

Abstract

ETS activities of natural zooplankton assemblages and some micronekton species from the eastern Banda Sea and western Arafura Sea (Indonesia) were measured during the SE and NW monsoons, when respectively rich upwehng and poor downwelling condtlons occur. Weight-specific ETS activities of the zooplankton community decreased with depth; 13 to 20 % of this decrease was related to temperature, and another 5 to 10 % to hlgher water contents of the deeper samples. Large geographical dfferences, but no seasonal differences, were detected within the area studled. About 65 % of the total zooplankton ETS activity in the upper 500 m was confined to the upper 100 m. Day/ night differences in ETS profiles were observed during the less fertile NW monsoon period, attributed to diel vertical migration of the zooplankton, and resulting in a 9 to 36 90 lower activity in the water column during daytime. Since no diel migration by the zooplankton was seen in the fertlle SE monsoon season, the abundance of food, or the necessity to conserve energy, seems a major factor in determining d e l vertical migration. Of the micronekton examined, shallow-living species and those performing d e l vertical migration showed higher weight-specific ETS activities than deeper living and non-migrating species. Myctophid fishes and carid crustaceans showed very high weight-specific activities; chauliodontids, gonostomatids, euphausids and sergestids moderate activities; and leptocephali, chdeiognains, saips, siphonophores and medusas low activities. None of the micronekton species investigated showed seasonal differences in ETS activity.

Ecology of Anguilliform Leptocephali: Remarkable Transparent Fish Larvae of the Ocean Surface Layer

“…ETS activity is assumed to represent the maximum potential oxygen consumption rate (see Pfeiler and Govoni 1993). This study clearly showed a decrease in wet-weight-specific ETS activity with increase in body length in premetamorphic leptocephali (Pfeiler and Govoni 1993), which was consistent with a previous ETS activity study that included leptocephali (Schalk 1988). Bonefish leptocephali were also tested in respirometers, which showed that respiration rates increased during metamorphosis as GAG and other materials were converted into respiring tissues (Pfeiler and Govoni 1993).…”

Mesozooplankton carbon requirement in the Tyrrhenian Sea: its vertical distribution, diel variability and relation to particle flux

“…The vertical distribution pattern of euphausiids does not seem to be at all correlated to the carbon consumption ver tical trend during the 24 h cycle. As previously reported (Torres et al 1979, Schalk 1988, Minutoli & Guglielmo 2009, at midday, afternoon and midnight, the vertical distribution of ETS activity in the present study resembled that of euphausiid abundance. On the other hand, in the morning, the high values of ETS activity were not associated with high eu phau siid abundance.…”

“…The rate-limiting step of ETS is the coenzyme Q-cytochrome b complex oxidation, that can be measured after the reaction of the complex with the artificial electron acceptor 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) (Pa ckard 1971). This reaction is influenced by various factors, such as temperature, salinity and sexual stage (Torres et al 1979, Ikeda & Fay 1981, Raymont 1983, Schalk 1988, even if adaptations to environmental conditions are possible (Anraku 1964, Musayeva & Shushkina 1978, Båmstedt 1980, Hirche 1984. Several papers have shown a good correlation between ETS activity and in vivo respiration (Packard et al 1974, Kenner & Ahmed 1975, Owens & King 1975, Devol & Packard 1978, so that ETS activity can be used as an estimate of mesozooplankton respiration rates.…”

Electron transport system (ETS) activity as a measure of benthic macrofaunal metabolism

“…The effect of storage of the homogenate prior to the ETS assay was reviewed recently by Schalk (1988) and the literature is contradictory. Part of the explanation may be that some of the observations in previous studies were so infrequent that an initial increase might have been overlooked if it were followed in turn by a rapid decrease.…”