DIET OF HARBOR PORPOISES IN THE KATTEGAT AND SKAGERRAK SEAS: ACCOUNTING FOR INDIVIDUAL VARIATION AND SAMPLE SIZE

Stomach contents of 112 bycaught harbor porpoises ( Phocoena phocoena ) collected between 1989 and 1996 in the Kattegat and Skagerrak seas were analyzed to describe diet composition and estimate prey size, to examine sample size requirements, and to compare juvenile and adult diets. Although porpoises preyed on a variety of species, only a few contributed substantially to the diet. Atlantic herring ( Clupea harengus ) was the dominating prey species for both juveniles and adults. Our results, in combination with those from previous studies, suggest that where herring is a dominant food source, porpoises prey primarily on size classes containing mature or maturing individuals. Further, we also show that Atlantic hagfish ( Myxine glutinosa ) may be an important food resource, at least for adult porpoises. Examination of sample size requirement showed that, depending on the taxonomic level used to describe the diet, a minimum of 35–71 stomachs are needed to be confident that all common prey species will be found.     

太平洋中西部海域浮游植物营养盐的潜在限制

2009年8月至9月期间在太平洋西部N1站和中部N2站进行现场营养盐加富培养实验。结果显示:N1站,浮游植物生物量对N或者P添加都有较强的响应,其中N+P+Si组和N+P组浮游植物长势迅速,叶绿素a从初始的0.03μg/L分别达到2.12μg/L和1.83μg/L,同时P先于N和Si之前被耗尽;说明N1站为N、P共同限制,P是首要限制因子。而N2站,浮游植物生物量仅对N、P共同添加有明显响应,N先于P和Si被浮游植物消耗殆尽。利用培养过程中营养盐比值变化推断,N1站浮游植物以低于Redfield ratio(16N∶1P)吸收N和P;而N2站浮游植物以高于Redfield ratio(16N∶1P)吸收N和P。这可能解释了太平洋西部的寡营养盐海域为潜在P限制,而在太平洋中部海域则为潜在N限制。     

The influence of prolonged di(2-ethylhexyl)phthalate treatment on the dolichol and dolichyl-P content of rat liver

Dolichols and glycosyl transferase activities were studied in rat liver fractions after treatment with the plasticizer di(2-ethylhexyl)phthalate, an inducer of peroxisomes and mitochondria. After a few weeks of treatment with 2% plasticizer in the diet, the amount of dolichol is more than doubled in the lysosomes but not in the microsomes while dolichyl-P decreased by 50% in the microsomes but not in the lysosomes. The isoprenoid pattern for dolichol and dolichyl-P, respectively, is modified to longer polyprenols in the two fractions as seen in the percent distribution of the individual isoprenes. Dolichyl-P and protein glycosylation by N-acetylglucosamine and mannose decreased considerably. Incubation with mixtures containing exogenous dolichyl-P did not increase protein glycosylation. Phthalate ester treatment for 2 years increased dolichol content above the control values even when the dose was decreased a hundred times, to 0.02%. The results demonstrate a compartmentalization of dolichol and dolichyl-P distribution, and the induction studies suggest that hepatocytes possess separate regulating mechanisms for these two compounds.     

Laboratory experiments in the ecological work on rockpool animals with special notes on the ostracodHeterocypris salinus

Summary 1. The relations between environment and fauna of rockpools are briefly discussed on the basis of information available in literature.2. The necessity of combining field studies and laboratory experiments, as well as the need to know the extreme physico-chemical values of the environment for pertinent experimentation, is stressed.3. Rockpool organisms are exposed to extreme conditions and diurnal fluctuation of salinity, temperature, pH, oxygen concentration and illuminance; with the exception of salinity, all these factors vary greatly especially during a sunny day.4. Many rockpool organisms exhibit diurnal vertical migrations; this is demonstrated quantitatively for the ostracodHeterocypris salinus Brady, which is found in the shallow parts of the pools at night and in the deep parts during the daytime.5. In laboratory experimentsH. salinus is shown to be negatively phototactic.6.H. salinus survives better in hypo- than in hyperoxygenated (or in 100% aerated) water but does not respond to alternatives offering hypo- and hypersaturation.7.H. salinus shows a well defined reaction to different temperatures with a preference for 15° C when the alternative is 22° C.8. The investigated populations ofH. salinus andGammarus duebeni exhibit definite preferences for the most common rockpool salinity, 6 , which is also found in the surrounding sea.9. The possible influences of light, oxygen, carbon dioxide and temperature combinations and variations on the diurnal distribution of rockpool organisms are discussed.

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Laboratoire expérimentaux aux recherches écologiques sur les animaux des flaques d'eau en particulier sur l'ostracodeHeterocypris salinus

Extrait Les organismes colonisant les flaques vivent dans des conditions très variables et souvent extrêmes au point de vue physico-chimique. Pour bien déterminer les particularités écologiques de ces organismes il est nécessaire d'effectuer des prospections aussi bien que des études de laboratoire. Pour que les études faites en laboratoire soient adéquates, les variations annuelles et diurnes des facteurs écologiques doivent être connus. Il importe également de mettre les cas extrêmes bien en évidence. Dans cette étude nous présentons un certain nombre d'expériences sur l'ostracodeHeterocypris salinus Brady, faites au laboratoire et fondées sur des prélèvements effectués tout le long du jour dans une flaque très riche en organismes de cette espèce, située dans le nord de la Baltique. En même temps que la distribution des organismes furent observées et notées, pendant les 24 heures, des variations de salinité, de température, de pH, de teneur en oxygén et d'illumination. Comme on pouvait s'y attendre, ces facteurs-ci présentent de grandes fluctuations, à l'exception de la salinité qui ne varie pas. Dans la nuit 101 ostracodes furent retrouvés dans des algues des couches superficielles tandis que, de jour, 6 individus seulement furent récoltés au même niveau et dans la même quantité d'algues. Afin d'expliquer la variation que font ressortir ces chiffres, nous avons procédé à des expériences de préférence et de résistance en soumettantH. salinus à des varations de facteurs mentionnés. Ces expériences montrent queH. salinus est de façon marquée négativement phototactique et très résistant dans une eau faiblement oxygénée, sans être pour cela en état de choisir activement entre saturation faible ou saturation élevée (34 et 410% de saturation respectivement). La température et la salinité sont par contre des facteurs dont la force d'attraction est en rapport étroit avec l'intensité.H. salinus préfère de manière active 15° C à 22° C et 6 à 20, 12 ou 1 S. Ces résultats peuvent contribuer à expliquer les variations de distribution relevées, mais il faut également prendre en considération l'éffet convergent des différents facteurs, effet qui se réalise différemment selon l'intensité de chaque facteur.H. salinus réagit fortement à l'illumination et à la température, probablement aussi à la teneur en oxygéne et en gaz carbonique, tandis que, dans le type examiné de flaques, la salinité est de moindre importance. Les résultats présentés indiquent queH. salinus est bien préadapté au milieu des flaques, tout commeGammarus duebeni, autre organisme, et mieux connu, colonisant le même biotope.

     

Population dynamics and salinity tolerance of Hyadesia fusca (Lohman) (Acarina,Sarcoptiformes) from brackish water rockpools,with notes on the microenvironment inside Enteromorpha tubes

Summary The salt water mite Hyadesia fusca has been recorded from Scandinavia for the first time. It is entirely restricted to the green alga Enteromorpha spp. in the littoral zone or in rockpools. The algae serve as substratum, food and breeding room but they also give rise to violent fluctuations in abiotic environmental parameters. However, oxygen availability and hydrogen-ion activities do not differ very much inside and outside the algal thalli. The fluctuations recorded are between 2 and 12 g O₂·10^-7 cm^-2 min^-1 and between pH 8.5 and 10.1. H. fusca dominates the fauna of many brackish water rockpools. During breeding in June and July more than 900 animals, mostly larvae, may be found on 0.1 g Enteromorpha dry weight. In winter an average of 13 hibernating animals were found per 0.1 g algae. Copulation follows after a long precopula with the male riding on the female. The newborn larvae are often found near the rhizomes inside the algal tubes.The mite is very tolerant of salinity variations. In laboratory experiments more than 4 weeks of survival, copulation, breeding and larval growth were found to be almost equally successful in salinities between 0.5 and 40S. Hyadesia fusca is a characteristic member of the rockpool ecosystem. It is often very abundant, one of the few Enteromorpha grazers of of the ecosystem and it serves as food for fishes in the system. Together with some better known crustaceans this mite because of its tolerance and survival capabilities must be considered one of the hardiest members of the unstable rockpool ecosystems.     

Effects of dietary di(2-ethylhexyl)phthalate on the structure and function of rat hepatocytes

The effect of the plasticizer di(2-ethylhexyl)phthalate on the intracellular membranes of hepatocytes was investigated. Supplementation of the diet with 2% plasticizer resulted in the appearance of a large number of peroxisomes, and the number of mitochondria was also greatly increased. No significant change in the amount or appearance of the endoplasmic reticulum was detected. The oxidation of palmitoyl-CoA in peroxisomes and the activities of carnitine-acyltransferases are increased to a great extent in both mitochondria and peroxisomes. Intact respiratory control and oxidative phosphorylation indicated that mitochondrial integrity was maintained during the induction. In microsomes, cytochrome P-450 and NADPH-cytochrome c reductase are elevated. The increased incorporation of glycerol into phospholipids indicated an increased rate of synthesis. The induction of peroxisomal and mitochondrial membranes and enzymes, but not of the membranes of the endoplasmic reticulum, by phthalate esters is an unusual and valuable induction pattern not seen with other inducers.