Hydrostatic pressure-induced apoptosis on nauplii of Calanus sinicus

The effect of hydrostatic pressure on embryonic development of the calanoid copepod Calanus sinicus was studied. Differences of pressure effect among blastomere stages, 1-cell, 2-cell, 4-cell, 8-cell, 16-cell, blastula and limb-bud stage, were examined under two pressurizing conditions, abruptly (10 atm/min) and gradually (0.1 atm/min) increasing. Egg hatching success, deformity frequency and apoptotic cell degradation of hatched nauplii were examined. Egg hatching success rate was not significantly different between blastomere stages, and also between pressurizing conditions. Deformity frequencies of hatched nauplii were low in the early 1-cell and 2-cell stages, and high in the later blastula and limb-bud stages, in both abrupt and gradual pressurizing conditions. On the other hand, in regard to difference in pressurizing conditions, deformity frequency in gradual pressurizing was significantly higher than that in abrupt pressurizing rate. Gradual pressure increase seems to be more harmful to C. sinicus eggs than abrupt pressure change. Apoptosis induced in nauplii by hydrostatic pressure was detected for the first time in marine zooplankton. The embryos of C. sinicus are sensitive to pressure variations, that is, these embryos are supposed to sink to deeper waters, incurring greater risk of having deformities. In the field, C. sinicus ascend to the surface and spawn at night. By looking from this upward behavior, eggs are spawned at lower pressure and warmer temperature. Probably, the harmless low pressure and warm temperature lead eggs to hatch early and to recruit successfully.     

Development of the gooseneck barnacle Pollicipes polymerus (Cirripedia: Lepadomorpha): Fertilization through settlement

Pollicipes polymerus (Sowerby, 1833) is a common barnacle in rocky intertidal zones of the West Coast of North America whose development has been previously undescribed in detail. In the present study, certain aspects of the development of P. polymerus are recorded from fertilization through settlement. In vitro fertilization has been accomplished using already-implanted sperm plus ovulating eggs and oviducal gland fluid. The eggs are small (about 100 μ diameter at fertilization; 90 x 140 μ at first cleavage) and somewhat yolky. Embryos obtained from brooding adults and from in vitro fertilization were reared in glass dishes until hatching. Cleavage was total, asynchronous and unequal. Division of the D macromere lagged behind division of the other blastomeres, and gastrulation occurred by epiboly so that blastoderm surrounded the macromeres. The nauplii hatched an average of 25.4 days (range was 20.3 to 30.1 days) after fertilization, and molted within 1 day to Stage II nauplii. From Stages II through VI the nauplii required food. As they grew from stage to stage, the number of setae per appendage increased. Nauplii have feathery and hispid-type setae, previously described only in Chthamalus aestuarii. In contrast to other pedunculate larvae which have been described, P. polymerus nauplii are small and have specialized feathery setae. Cypris-larva settlement was stimulated only when healthy adult peduncles were available, thus showing an affinity for its own species.     

Deposit-feeding amphipods (Monoporeia affinis) reduce the recruitment of copepod nauplii from benthic resting eggs in the northern Baltic Sea

We experimentally investigated the effect of different densities of the burrowing, deposit-feeding amphipod Monoporeia affinis on the recruitment of zooplankton from benthic resting eggs. Intact sediment cores with in situ density and species composition of zooplankton resting eggs and benthic fauna were collected in the northern Bothnian Sea, part of the Baltic Sea. We removed as many M. affinis as possible from the cores and then added different numbers of M. affinis to the cores to generate a range of densities. The cores were exposed to different densities of M. affinis for either 3 or 40 days, after which the hatched zooplankton was registered. One subset of the cores were initially incubated under low temperature (2–3 °C, to prevent hatching) for 37 days (the resting phase), to allow for effects of M. affinis on unhatched resting eggs. These cores were then incubated under higher temperature (13 °C) for 3 days (the hatching phase), to induce hatching and allow for effects on hatching or hatched specimens. In a second subset of cores with the same time and temperature schedule, the M. affinis density was experimentally reduced at the start of the hatching phase, to evaluate the effect of M. affinis during the hatching phase. To a third subset of cores, we immediately initiated the hatching phase, without an experimental resting phase, to evaluate the effects induced during the resting phase. The most common zooplankton species that hatched was Eurytemora affinis (Copepoda), followed by Bosmina longispina maritima (Cladocera). In all cores that were subjected to a resting phase, the numbers of hatched E. affinis were log-linearly negatively related to density of M. affinis. An increase of M. affinis density from 1,000 to 5,000 individuals m⁻², normal field densities, reduced the hatching by 60–70%. The negative impact was mainly exerted during the hatching phase, suggesting predation on, burial of or physical injury of hatching nauplii or eggs in a late development stage as likely mechanisms. Also, the number of B. longispina maritima that hatched was reduced by M. affinis during the hatching phase, but no clear relation to density of M. affinis could be identified. The results show that M. affinis can reduce recruitment to zooplankton from benthic resting eggs. Such impact by the benthos on resting stages of zooplankton is therefore a potentially significant link between the benthic and pelagic systems. Received: 10 August 2000 / Accepted: 13 November 2000     

Hatching and viability of copepod eggs at two stages of embryological development: anoxic/hypoxic effect

The effects of low oxygen concentrations on the hatching and viability of copepod eggs at two stages of embryological development were investigated. Fully developed eggs from Acartia tonsa (Dana) and Labidocera aestiva (Wheeler) collected between July and September 1991 at Turkey Point, Florida, USA, hatched at lower oxygen concentrations than newly spawned eggs given the same incubation periods. Since many of the newly spawned eggs subsequently hatched when exposed to normoxic conditions, it is likely that the exposure to low oxygen delayed embryonic development. At oxygen concentrations where no initial hatching occurred, the subsequent hatching success of fully developed eggs of A. tonsa was higher than that of newly spawned eggs, indicating that newly spawned eggs were more sensitive to low oxygen concentrations. No such difference was observed for the eggs of L. aestiva.     

Effects of various environmental factors on egg development of several species of Acartia in Southern California

The hatching of the eggs of 3 Acartia species (A. tonsa, A. clausi, and Acartia sp. I) spawned in the laboratory and the eggs of Acartia (species undetermined) isolated from natural bottom sediments was examined under various environmental conditions (temperature, salinity and temperature combinations, oxygen concentration, illumination, and the presence of bottom mud). The range of temperature and salinity in which eggs hatched differed from one species to another. Egg hatching was inhibited under certain environmental conditions for all species, although egg viability under such conditions varied from one species to another. In relation to these findings, habitat separation of planktonic Acartia populations and the role of dormant eggs during their seasonal absence in the plankton of Southern California coastal waters are discussed.     

Calanoid resting eggs in the Baltic Sea: implications for the population dynamics of Acartia bifilosa (Copepoda)

Resting eggs of Acartia spp. (presumably A. bifilosa Giesbr.) at densities between 65 and 125 eggs cm^-2 were found in sediment off the southern coast of Finland and represent the first observations of dormant calanoid eggs in the Baltic Sea. The highest egg densities were found at sediment depths between 4 and 8 cm. The hatching percentage varied between 0 and 90% in the different sediment layers and at different experimental temperatures (13, 16 and 19°C). Some nauplii emerged from the eggs extracted from sediment layers 9 to 10 cm beneath the surface layer and other nauplii emerged from eggs after 82 d of dark storage at 3°C. Light was not needed to trigger hatching; the nauplii were able to hatch in darkness when the eggs were resuspended in filtered seawater. Indirect evidence suggests that the marked spring peak of Acartia spp. nauplii seen in a monitoring data from the years 1973 to 1984 was derived from benthic eggs and not from spawning. The possible mechanisms for induction of hatching and the adaptive benefits of resting egg production for A. bifilosa are discussed.     

Impact of a burrowing deposit-feeder, Monoporeia affinis, on viable zooplankton resting eggs in the northern Baltic Sea

We investigated the effect of different densities of the burrowing deposit-feeding amphipod Monoporeia affinis on the potential for recruitment of zooplankton from benthic resting eggs. Hatching of resting eggs was induced in the laboratory on sliced and resuspended 1-cm depth-sections of sediment cores, collected at six stations in an archipelago area of the Gulf of Bothnia, Baltic Sea. The uppermost 5 cm of the sediment was studied. The most common species that hatched was Eurytemora affinis (Copepoda). Individuals from another copepod genus, Acartia, hatched in significant numbers only in the cores from two stations with low amphipod abundance. Cores from stations with high amphipod densities showed a deeper distribution of emerging E. affinis nauplii compared with stations with few amphipods; the oxidised sediment layer was also deeper at high M. affinis densities than at low. Total (0 to 5 cm strata pooled) number of hatched E. affinis nauplii was independent of amphipod density. This indicates that the effect of M. affinis on E. affinis eggs involves deeper burial due to bioturbation, rather than predation. Decreased benthic recruitment of zooplankton at localities with high M. affinis density is suggested, since more deeply positioned eggs are less likely to hatch. When hatching was induced in intact, non-sliced cores from one station, the number of E. affinis nauplii that hatched was on average 43% of the number that hatched in the upper centimetre of the sliced cores from the same station. This fraction (43%), if applied to the other stations, implied a potential for benthic recruitment of up to 80 000 ind m⁻² for E. affinis. Due to its high abundance, M. affinis is likely to greatly reduce benthic recruitment of zooplankton in this system. Received: 17 September 1999 / Accepted: 23 February 2000     

Calanoid copepod eggs in sea-bottom muds. III. Effects of temperature,salinity and other factors on the hatching of resting eggs of Tortanus forcipatus

The “resting” eggs of a marine neritic copepod, Tortanus forcipatus Giesbrecht, recovered from sea-bottom sediment were hatched in the laboratory. Hatching occurred at temperatures of 13° to 30°C, no eggs hatched at 10°C. Temperatures around 25°C were found to be optimal for hatching, although the range of optimal temperatures for hatching was approximately 5°C lower in eggs stored for 14 to 15 months than in those stored for 1 to 2 months. A wide range of salinity, from 18 to 54%S, was favourable for hachting. Eggs failed to hatch within the sediment mud, which suggests that they are in a state of dormancy in the mud. Hatching was successful under both light and dark conditions.     

Laboratory rearing of the clupeid fish Harengula pensacolae from fertilized eggs

Pelagic eggs of the scaled sardine Harengula pensacolae (Goode and Bean), have been hatched and reared in the laboratory for the first time. Larvae were reared in two 75 l aquaria under constant illumination, at an average temperature of 26.2°C. Zooplankton collected in a 35 mesh net was fed to the newly hatched larvae, and the diet was supplemented later with Artemia salina nauplii and a pelleted food. Larvae hatched at 4 mm TL (total length), and metamorphosed about 25 days later at 25 to 30 mm TL. Survivors averaged 76 mm TL 100 days after hatching. Of the 500 incubated eggs, 2.8% survived until 20 days, after which no significant natural mortality occurred. Sources of natural mortality included starvation, a copepod parasite (Caligus sp.), and injuries from contact with the sides of the tank. Larvae began feeding at 4.5 mm TL on copepod nauplii averaging 62 in body width. Scaled sardines were photopositive throughout the larval stage.Contribution No. 149, Bureau of Commercial Fisheries Tropical Atlantic Biological Laboratory, Miami, Florida 33149, USA.     

Über den einfluß des hydrostatischen druckes auf die ultrastrukturen von zellen und geweben. III. Untersuchungen an filament-und mikrotubulisystemen verschiedener gewebe mariner muscheln und Branchiostoma lanceolatum

Employing the technique of pressure fixation, the effect of high hydrostatic pressure (1 to 800 atm) at 5°C has been investigated on cilia of the gill epithelium in Modiolus modiolus, Mytilus edulis (Baltic and North Seas), and on the skin and muscle cells of Branchiostoma lanceolatum (Pallas). With increasing pressure, the filaments and tubuli are increasingly disorganized to an electron-dense material, which seems to be a conglomeration of the globular structure units. Minimum pressure causing disintegration of filaments and tubules is 300 atm; 600 atm is critical, especially for filaments in skin cells of B. lanceolatum. Whereas the filaments do not show any intermediate stages of damage at any one pressure, microtubules show different stages of disorganization. There seems to be a direct relation between motility and structural organization of cilia. Probably the mechanisms of disintegration of filaments and microtubules are related to the enzymatic activities and the protein-protein-interactions of the subunits. The difference between di-and monomer enzymatic systems in the structures may be important for pressure resistance of the organelles.     

Predation of calanoid copepods on their own and other copepods’ offspring

Predation of eggs and nauplii by adult copepods is often used to explain unexpected death rates in population dynamics studies, but the phenomenon has been rarely investigated or quantified. Therefore, we studied the predatory feeding of adult females (Acartia clausi, Centropages hamatus, Centropages typicus, and Temora longicornis) on their own and other species’ eggs and young nauplii with different densities of single animal-prey, mixtures of animal-prey and in the presence of diatoms. All species preyed on eggs and nauplii of their own and all other species. Maximal egg predation varied between 7 and 64 eggs fem^?1 day^?1. Ingestion of Centropages spp. eggs was lowest, potentially due to the spiny egg surface. Maximal feeding rates on nauplii ranged from 5 to 45 nauplii fem^?1 day^?1. T. longicornis preferred eggs, when eggs and nauplii were offered together at the same densities, and the other predators selected for nauplii. At a diatom concentration of 60 μg C l^?1 predation on eggs by C. typicus was higher than without algae, whereas A. clausi and T. longicornis did not change their uptake of eggs. Feeding on nauplii in the presence of diatoms was again enhanced in C. typicus, and unaffected in A. clausi and C. hamatus. T. longicornis reduced its feeding on nauplii in the presence of diatoms. Calculated predation rates, using field abundances of predators and prey, suggest that predation of copepods on their own young stages may account for ca. 30 % of total mortality of young stages in North Sea copepod populations.     

A study of the variations in lipid levels,lipid class composition and fatty acid composition in the first stages ofArtemia sp.

The lipid class composition and the fatty acid composition of total lipids of the cysts, newly hatched nauplii and 24-h-old metanauplii of a Spanish parthenogenetic diploid strain ofArtemia sp. were studied. Substantial differences in the total lipid level occurred among these stages, with a marked increase from the cyst to the nauplii being followed by a decrease in the metanaupliar stages. This variation affected the absolute levels (mg/g dry wt) of the total lipid classes and individual fatty acids, although the percent composition of the fatty acids in total lipid was essentially unchanged. An exception occurred during hatching in that the percentages of 16:0 and 16:1n-7 in total lipid decreased whereas that of 20: 5n-3 increased. The lipid classes showed higher variation than the fatty acids both in absolute and in relative terms, and in particular, the ratio of phosphatidylcholine:phosphatidylethanolamine decreased progressively from cysts to nauplii and metanauplii. The implications of these findings for the use ofArtemia sp. as a larval feed in aquaculture are considered.     

Veränderungen der Eikapselvolumina während der entwicklung verschiedener Opisthobranchier-Arten (Mollusca,Gastropoda)

An attempt has been made to estimate volumes of eggs and egg-capsules employing the formula of the rotationellipsoid. Measurements of the following stages have been made: immediately after oviposition; blastula; gastrula; appearance of velumanlage; velarcilia, foot and velum small; velarcilia, foot and velum distinct; 1 to 2 days before hatching; hatching. Calculations permitt analysis of: (1) relationship between egg-case volume and egg-volume; (2) capsule volumes during development until hatching in comparison to those after oviposition (enlargement factor). The sacoglossan nudibranch Elysia viridis shows no increase in capsule volume during development. The nudibranchs Catriona aurantia, Tergipes despectus, Eubranchus exiguus, Eubranchus cingulatus, Eubranchus pallidus, Eubranchus farrani and Janolus cristatus reveal a distinct increase in capsule volume when velarcilia, foot, and velum appear. The degree of eggcapsule enlargement and its intensity during development exhibit interspecific differences. The results of this and of a previous paper (Kress, 1971) are compared and discussed with respect to possible explanations for the enlargements, (e.g. excretion of larval kidneys, composition of capsular fluid, influence of salinity).     

High reproduction of <Emphasis Type="Italic">Calanus finmarchicus</Emphasis> during a diatom-dominated spring bloom

Feeding, egg production, hatching success and early naupliar development of Calanus finmarchicus were measured in three north Norwegian fjords during a spring bloom dominated by diatoms and the haptophyte Phaeocystis pouchetii. Majority of the copepod diet consisted of diatoms, mainly Thalassiosira spp. and Chaetoceros spp., with clearance rates up to 10 ml ind⁻¹ h⁻¹ for individual algae species/groups. Egg production rates were high, ranging from ca 40 up to 90 eggs f⁻¹ d⁻¹, with a hatching success of 70–85%, and fast naupliar development through the first non-feeding stages. There was no correlation between the egg or nauplii production and diatom abundance, but the hatching success was slightly negatively correlated with diatom biomass. However, the overall high reproductive rates suggested that the main food items were not harmful for C. finmarchicus reproduction in the area, although direct chemical measurements were not conducted. The high population egg production (>1,20,000 eggs m⁻² d⁻¹) indicated that a large part of the annual reproduction took place during the investigation, which stresses the importance of diatom-dominated spring phytoplankton bloom for population recruitment of C. finmarchicus in these northern ecosystems.     

Effects of season and maternal food on<Emphasis Type="Italic"> Calanus finmarchicus</Emphasis> reproduction,with emphasis on free amino acids

Effects of maternal food environment and season were examined during spring and autumn on females, eggs and nauplii of Calanus finmarchicus, in different natural prey suspensions or cultures of Rhodomonas baltica. Females sampled in spring were in general larger, had higher protein content, and showed higher egg production and hatching rates, than in autumn. The cumulative egg production was almost double in spring compared to autumn (females fed R. baltica). Females had higher content of free amino acids (FAA) and free essential amino acids (EAA) in autumn than in the spring. Also, the FAA contents in eggs and nauplii were higher in autumn than in spring. In contrast, the composition of EAA in eggs was constant between seasons, indicating maternal regulation. The highest cumulative egg production was correlated with a high similarity in the free pool of EAA in the food suspension and the female copepod. Thus, the data support the hypothesis that similarity in the free pool of EAA of diet and female promotes high fecundity and egg hatching success in C. finmarchicus.     

Ontogenetic diel vertical migration of the planktonic copepod Calanus sinicus in the Inland Sea of Japan

The ontogenetic diel vertical migration of the planktonic copepod Calanus sinicus was investigated in the Inland Sea of Japan in June 1989, when the water column was thermally weakly stratified. Because of fewer eggs and less variation in their abundance, nocturnal spawning was not apparent. A pronounced upward migration occurred in NIII. NIII to CIII resided in the upper 20 m layer throughout the day, and from CIV on their median depths descended. CV and adult females underwent significant diel vertical migration, whereas adult males did not migrate. By integrating the results from the present study and those from our previous investigations (in August–September 1988, November 1988 and March 1989), we review seasonal variation in the ontogenetic diel vertical migration of C. sinicus. Spawning was largely nocturnal, reaching its maximum level around dawn, but spawning depth and fecundity changed seasonally. The distribution of pre-feeding stages, NI and NII, was similar to that of eggs. A pronounced upward migration always occurred in the first feeding stage, NIII, and late nauplii and early copepodites always resided in the food-rich upper layer, indicating that upward migration by NIII is feeding migration. As the stages progressed, they extended their vertical distribution range, and CV and adult females usually underwent diel vertical migration. However, the pattern and strength of this migration differed seasonally. Their day depths increased with the increase of relative biomass of planktivorous fish, indicating that predator avoidance induces their diurnal downward migration. High chlorophyll a concentrations in the upper layer (<15 m deep) relative to the lower layer (>20 m deep) amplified their diel vertical migrations. Diel vertical migration of C. sinicus is a phenotypic behavior.     

Ontogenetic diel vertical migration of the planktonic copepodCalanus sinicus in the Inland Sea of Japan

The ontogenetic diel vertical migration of the planktonic copepodCalanus sinicus was investigated in the Inland Sea of Japan in summer 1988, when the water was thermally stratified with a thermocline of ca 5 °C between 35 and 45 m. Stage-specific differences in the diel vertical migration behavior ofC. sinicus were found. Eggs were spawned primarily within the surface-waters between midnight and dawn by ascending females, and sank gradually to deeper waters until they hatched into nauplii. Non-feeding nauplius stages (NI and II) were distributed throughout the water column, but the first feeding stage (NIII) performed an ontogenetic upward migration. NIV to VI and copepodite (C) stages I to III continuously aggregated in the phytoplankton-rich euphotic layer. However, the depth of the median CI to III populations descended as stage progressed. The onset of prominent diel vertical migration took place in CIV, and the amplitude of vertical migration increased with age, being maximal in adult females (CVI). Adult males (CVI), however, remained in the layer below 20 m, and did not migrate dielly. The ecological significance of ontogenetic diel vertical migration is discussed.     

Wave action: the environmental trigger for hatching in the California grunion Leuresthes tenuis (Teleostei: Atherinopsidae)

 California grunion Leuresthes tenuis (Teleostei: Atherinopsidae) emerge from the ocean to spawn on beaches of southern California. Grunion eggs do not hatch at a set developmental age, but remain in the sand until turbulent surf at high tide washes them out to sea. In previously studied fishes and amphibians that lay eggs terrestrially, low oxygen is the trigger for hatching in water, and high oxygen tensions inhibit hatching. For the grunion, however, eggs placed in air, seawater and oil did not hatch at any at oxygen tension until they were agitated in fluid. Following agitation in seawater, all eggs hatched within several minutes. Grunion eggs in normoxic or hyperoxic water hatched significantly faster than eggs agitated at the lowest oxygen tensions. Mechanical agitation, not hypoxia, is the environmental trigger for hatching in California grunion eggs. Received: 15 May 1999 / Accepted: 5 April 2000     

Preferential incubation positions for different sized eggs and their influence on incubation period and hatching asynchrony in Snares crested (<Emphasis Type="Italic">Eudyptes robustus</Emphasis>) and yellow-eyed penguins (<Emphasis Type="Italic">Megadyptes antipodes</Emphasis>)

In crested penguins (Eudyptes spp.), second-laid eggs typically hatch before first eggs. Amongst a variety of factors that have been considered as mechanisms underlying this reversal, has been the idea that crested penguins can adjust the degree of hatching asynchrony by manipulating egg positions (i.e. placing the smaller first egg in the supposedly thermally disadvantaged anterior position) during incubation (termed Preferential Incubation Hypothesis). We tested this in the Snares crested penguin (Eudyptes robustus) and the closely related, but synchronously-hatching, yellow-eyed penguin (Megadyptes antipodes). Snares crested penguins were more likely to place their first eggs, which are smaller than second eggs, in the anterior incubation position than were yellow-eyed penguins, which have a clutch of two similar-sized eggs. But when yellow-eyed penguins, a non-brood reducing species, were provided with an artificial size-dimorphic clutch, they also placed smaller eggs more frequently in the anterior position, suggesting that a general preference exists among penguins to place smaller eggs in the anterior position. Egg temperatures of small first eggs of Snares crested penguins were higher in the anterior than in the posterior position. Large first eggs in lesser size-dimorphic clutches experienced high temperature differences in relation to position, while small first eggs in greater size-dimorphic clutches were incubated at similar temperatures. In yellow-eyed penguins, large eggs within clutches generally had higher egg temperatures than small eggs. Incubation periods of second eggs declined with increasing egg size. Egg-size variation, rather than egg positioning behaviour, influenced hatching patterns in Snares crested penguins. In lesser size-dimorphic clutches, second eggs were more likely to hatch first while in greater size-dimorphic clutches, small first eggs were more likely to hatch at the same time or before the second eggs. This was similar in yellow-eyed penguins, where second eggs hatched earlier in clutches with large first eggs. Our data contradicts the Preferential Incubation Hypothesis and we conclude that this hypothesis is unlikely to explain the reversed hatching asynchrony in crested penguins.Communicated by C. Brown     

Extensive cross-disciplinary analysis of biological and chemical control of Calanus finmarchicus reproduction during an aldehyde forming diatom bloom in mesocosms

Egg and faecal pellet production and egg hatching success of the calanoid copepod Calanus finmarchicus were monitored over a period of 14?days (14?C28 April, 2008) while fed water from 4 differently treated mesocosms and ambient water. Two of the mesocosms used were inoculated with the polyunsaturated aldehyde (PUA)-producing diatom Skeletonema marinoi, while 2 received only nutrient additions with or without silica. The mesocosms developed blooms of S. marinoi, mixed diatoms or the haptophyte Phaeocystis pouchetii, respectively. Faecal pellet production of C. finmarchicus increased with increasing food availability. Egg production increased with time in all mesocosms to a maximum single female production of 232 eggs female^?1?day^?1 (average of 90 eggs female^?1?day^?1) and followed the development of ciliates and P. pouchetii, but was not affected by the observed high (up to 15?nmol?L^?1) PUA production potential of the phytoplankton. The hatching success of the eggs produced on the mesocosm diets was high (78?C96%) and was not affected by either aldehydes in the maternal diet or exposure to the dissolved aldehydes in the water.