Weeks In Seawater Research Articles

Effects of dietary trimethylamine on the concentration of trimethylamine oxide in various tissues of the chum salmon, Oncorhynchus keta, in freshwater and sea-water environments

1. 1. Young chum salmon were given one or other of three diets that differed in TMA contents for 4 weeks in freshwater and for 3 weeks in sea-water after 2 weeks adaptation for sea-water. 2. 2. The growth of fish fed on the TMA I diet (TMA 17 mg/100 g) was greater than that of fish fed on the TMA II diet (TMA 171 mg/100 g). 3. 3. TMA and TMO concentrations in the various tissues of the fish were determined. The concentrations of TMA and TMO in the various tissues were influenced by the dietary TMA level and environmental sea-water. 4. 4. The freshwater, fish fed on the TMA I diet had higher TMA and TMO levels in the whole body, muscle and kidney than fish fed on the basal diet or the TMA II diet. 5. 5. Also, in sea-water, the TMA I diet enhanced the accumulation of TMA and TMO in the whole body, muscle, liver and kidney. 6. 6. The levels of TMO in the tissues such as the liver and kidney were increased by feeding TMA I diet, and those increases were higher in sea-water than in the freshwater environment. 7. 7. NPN levels in either freshwater or sea-water fish did not differ greatly between the diets. Except for the whole body and muscle slightly higher values were found in sea-water than in freshwater fish.

Photodegradation of the pyrethroid insecticide fenpropathrin in water, on soil and on plant foliage

AbstractThe photodegradation of fenpropathrin [(RS)‐α‐cyano‐3‐phenoxybenzyl 2,2,3,3‐tetramethylcyclopropanecarboxylate] (I), in water, on soil and on plant foliage, was investigated using 14C‐preparations labelled separately at the cyano group, cyclopropyl‐C1 or in the benzyl ring. On exposure to sunlight, I was photodecomposed with initial half‐lives of >6 weeks in distilled water, 6.0 weeks in humic acid aqueous solution, 2.7 weeks in river water, 1.6 weeks in sea water and 0.5 of a day in 2% aqueous acetone. A triplet photosensitiser, acetone, together with naturally occurring substances in river and sea water, including humic acid, enhanced the photodegradation of I. On three kinds of soil, I was rapidly photodegraded with initial half‐lives of 1–5 days, whereas it was fairly photostable on a mandarin orange leaf. The photoreactions involved were: decarboxylation, hydration of the cyano group to carboxamide, cleavage of the ester or the diphenyl ether linkage, hydrolysis of the carboxamide group to carboxyl, and hydroxylation at either or both of the gem dimethyl groups. The predominant reactions in water were decarboxylation, ester bond cleavage and photo‐induced evolution of [14C] carbon dioxide from the [14C] cyano label; on soil, hydration or ester bond cleavage predominated. The hydration was also of importance in river and sea water. Decarboxylation did not occur on soil and plant foliage.

Protein quality of Altex canola meal for juvenile chinook salmon ( Oncorhynchus tshawytscha) considering dietary protein and 3,5,3′-triiodo-L-thyronine content

Juvenile chinook salmon, reared in freshwater, were fed isocaloric dry diets varying in protein (29, 39 and 49%), Altex canola meal (0, 11.5 and 23% of dietary protein by replacement of fish meal) and 3,5,3′-triiodo-L-thyronine (T 3; 0, 5 and 25 ppm) content. Oregon moist pellets (OMP) served as a reference control diet. Fish were subsequently observed in seawater while fed OMP. The nutritive value of herring and canola meal was similar when diets contained 29 and 39% protein, but not when protein content was 49%. Chinook fed 49% protein diets grew significantly faster than those fed diets with 29% protein. Appetite and protein utilization were inversely related to dietary protein content. Chinook fed OMP grew faster than those fed 49% protein diets with canola meal, but not when canola meal was deleted. T 3 stimulation of growth of chinook fed 49% protein diets was positively correlated with the dietary concentration of canola meal and T 3. Dietary and hormonal treatment in freshwater did not influence chinook performance in seawater. Further, thyroid hypertrophy observed in fish fed diets with canola meal during freshwater residency did not persist after 5 weeks in seawater. It is concluded that Altex canola meal may comprise almost 25% of dietary protein without adversely influencing protein quality, provided that dietary glucosinolate content is below 2.65 μmoles/g dry diet (300 μg/g as 3-butenyl isothiocyanate). Dietary canola meal concentrations of 30% of dry matter (glucosinolate content > 2.65 μmoles/g dry diet) can be employed if 5 ppm of T 3 are administered simultaneously.

The Calcium-sensitive Cells of the Pars Intermedia in the Eel

In the pituitary, the PAS-positive calcium-sensitive (Ca-s) cells of the pars intermedia appear less active in seawater (SW)- than in freshwater (FW)-adapted eels. The kinetics of their response during adaptation to SW or readaptation to FW was investigated. Morphometric studies show that transfer to SW induces a rapid nuclear atrophy which accentuates in eels kept for several weeks in SW. Readaptation to FW stimulated the Ca-s cells after 2–10 days; after 1 or 2 months, the cells tend to be similar to those of eels kept in FW. Plasma calcium decreases slightly but significantly in SW eels. The response of the Ca-s cells is not modified by an ovine prolactin treatment inducing hypercalcemia, hypernatremia and stimulation of the corpuscles of Stannius. Minor changes occurring in the MSH cells remain difficult to interpret; the short stimulation during readaptation to FW may be related to a stress effect and/or to release of other peptides present in the MSH cells of fish.

Lead uptake from sea water and food, and lead loss in the common mussel Mytilus edulis

Common mussels, Mytilus edulis (shell length 19 to 21 mm, average dry weight 30 mg) were maintained for 6 weeks in sea water containing different concentrations of lead (0.005 to 5 mg · l-1). The lead concentration in the mussels' whole soft parts was analysed at different times during the experiment. A constant rate of lead uptake, linearly dependent on the lead concentration of the medium, was observed. Thus, the temporal change of the concentration factor is also linear (regression coefficient 149.9 daily). Rate of lead loss, measured after transferring the mussels into natural sea water, is linearly dependent on the original lead concentration in the soft parts. Rates of uptake and loss in large mussels (shell length 45 to 55 mm, average dry weight 750 mg) are less than those in small mussels (shell length 19 to 21 mm, average dry weight 30 mg). During a much more extended experimental period, adjustment to a steady state is expected to occur; rates of lead uptake and loss are then non-linear. Lead uptake by individual organs (kidney, gills, adductor muscle, digestive gland, foot, mantle with gonads) of large M. edulis (shell length 45 to 55 mm, average dry weight 750 mg) was analysed in 2 test series. In the test series “medium”, the mussels were kept in a seawater medium containing 0.01 mg. Pb.l-1. In the test series “food”, the mussels were kept in natural sea water but fed with the green algae Dunaliella marina containing lead (approximately 600 μg.g-1 dry weight). The lead quantity given per mussel per day was about 2 μg in both test series. Within 35 days, the mussels of test series “medium” took up 29% of the total amount of lead given, those of test series “food” took up 23.5%. In all organs, lead concentration increased, but rates of uptake differed; the kidney displayed by far the highest rate of uptake. With these physiological properties M. edulis is an ideal indicator organism for lead pollution in the marine environment. A biologic calibration curve, the relationship between lead concentration in the mussels' whole soft parts at equilibrium and lead concentration in sea water, is presented.

Potassium, sodium, magnesium and calcium contents of Chinook salmon tissues during various stages of the life cycle

1. 1. The potassium, sodium, magnesium and calcium contents of plasma, red cells, brain, heart, muscle, liver, kidney and gills have been measured in Chinook salmon ( Oncorhynchus tshawytscha) during four stages of the life cycle: (1) while juveniles in fresh water, (2) after 2 weeks in seawater, (3) as mature adults in the ocean, and (4) after 3–4 months of fasting at the spawning grounds. 2. 2. Although plasma cation concentrations changed with each alteration in ionic environment, a remarkable constancy of cellular cation composition is maintained except for the juveniles in seawater. 3. 3. The normal potassium/nitrogen ratio in the muscle of spawning salmon is inconsistent with the hypothesis that pathological hyperadrenocorticism occurs at this stage.

V.—Experiments and Observations on Crustacea: Part II. Moulting of Isopods

SUMMARY(1) Ligia, like other iposods, moults in two stages. First the coverin of the abdomen with that of the posterior three thoracic segments is es uviated. About four days later the anterior covering is thrown off. Th external changes that occur in the cuticle as it ages, and the behaviou of the animal during moult, are described.(2) At the moult the cuticle splits in two main directions: (i) transvers between the fourth and fifth (free) thoracic segments; (ii) longitudina at the coxotergal junctions of (free) thoracic segments 2 to 7, there being no coxotergal split in segment 1. Coxotergal splitting is an arthrostracai if not a peracaridan, feature.(3) Ligiæ that have fasted for many weeks in sea-water may still moult normally. It follows that onset of the moult is determined by an underlying cyclic change, not as Réaumur suggested by simple growth of the animal. A second moult during the period of fast was not observed.