Cytogenotoxicity and histopathological assessment of Lekki Lagoon and Ogun River in Synodontis clarias (Linnaeus, 1758)

The cytogenotoxicity and histopathological alterations induced by xenobiotics in Lekki Lagoon and Ogun River on Synodontis clarias were investigated. Fish from these water bodies and a fish farm (control) were examined for micronucleated, binucleated, and immature erythrocytes in both gill and peripheral blood. Also gill, liver, kidney, and ovary were processed for histopathology using hematoxylin-eosin staining. Concentrations of cadmium, zinc, lead and copper in the water were determined. There was significant (p < 0.05) increase in micronucleated, binucleated, and immature erythrocytes in both gill and peripheral blood of S. clarias from the lagoon and river compared to the reference site. Loss and disorganization of the primary and secondary lamellae, multifocal degeneration, hemorrhages, cellular infiltration, congestions, vacuolations, atresia, and necrosis were common lesions in the examined tissues of fish from the lagoon and river. Cd, Zn, Pb, and Cu in water samples from the lagoon and river were higher than the reference site. Xenobiotics in Lekki Lagoon and Ogun River, mostly metals, induced deoxyribonucleic acid (DNA) and pathological damage in S. clarias.     

Bioremediation of aquaculture wastewater from Mugil cephalus (Linnaeus, 1758) with different microalgae species

Current aquaculture practices have a detrimental impact on the environment, in particular due to the release of high concentration of nitrogen and phosphorus that can induce eutrophication. This study investigates and compares the capacity of three microalgae species Tetraselmis suecica, Isochrysis galbana and Dunaliella tertiolecta, in the bioremediation of grey mullet Mugil cephalus wastewater. The experiment was conducted in batch conditions for 7 days using completely mixed bubble column photobioreactors. After two days, T. suecica and D. tertiolecta were able to remove more than 90% of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP), whereas I. galbana removed only 32% and 79% of DIN and DIP, respectively. A higher biomass yield resulted for T. suecica (603?±?34?mg/L, mean?±?SE). This study confirms the potential to employ T. suecica in an Integrated Multi-Trophic Aquaculture system for bioremediation of wastewater and identifies D. tertiolecta as another valid candidate species. Moreover, these species can growth in unsterilized culture media, and this reduces energy consumption, costs and efforts.     

Hazardous and essential trace elements profile in the different soft tissues of Lithophaga lithophaga (Linnaeus, 1758) from Southern Adriatic Sea (Italy)

A characterization study of 7 hazardous (Hg, Pb, Cd, As, Cr, U, and Ni) and 11 essential (Co, Mo, Se, Cu, Zn, V, Ca, Al, Sr, Mn, and Fe) trace elements in date mussels (Lithophaga lithophaga,Linnaeus, 1758) was carried out by inductively coupled plasma mass spectrometer. Date mussels (231 individuals), caught in the Gulf of Manfredonia (Southern Italy), were divided into 4 size-related groups. The different tissues (muscle, stomach, hepatopancreas and rest of soft tissues) were separated and analyzed to study the capability of absorption of this species. No particular differences were reported on the basis of the shell size; the soft tissues play an important role on the accumulation levels of hazardous and essential trace elements. These marine animals may be considered a good bioindicator of marine environmental pollution for their longevity and habitat permanence peculiarities.     

Food composition and feeding behavior of shallow-water crinoids at Eilat (Red Sea)

The food of 3 feather-stars, Lamprometra klunzingeri Hartlaub, 1890), Heterometra savignii (J. Müller, 1841) and Capillaster multiradiatus (Linnaeus, 1758), from the shallow water of Eilat (Red Sea) was found to be composed of planktonic and semi-benthalic organisms with a strong dominance of zooplankton. Monthly analyses of stomach contents showed seasonal changes in the participation of various systematic units in the diet. Food-comprising organisms were found to be selected according to size, and those measuring up to 400 formed 90% of the diet.This research has been sponsored partly by the Oceanic Biology Branch, Office of Naval Research, U.S.A. under contract N 62558-4556 and contract F 671052 67C 0043 between the Office of N.R. and the Tel-Aviv University. It represents part of the M.Sc. thesis of the first named author (in the framework of Red Sea investigations headed by Dr. L. Fishelson).     

Food quality,spatial deployment,and the intensity of feeding interference in yellow baboons (Papio cynocephalus)

Summary Optimization models lead one to predict that the energy invested in competitive interference with feeding should increase as the quality of the contested food increases. This prediction was tested in a study of feeding interruptions involving juvenile yellow baboons (Papio cynocephalus) in Amboseli National Park, Kenya. For each of the 50 foods eaten by these young primates, 6 measures of food quality (energy content, protein content, yield, yield rate, processing value, and dispersion) and one measure of the spatial deployment of baboons (number of neighbors) were examined for correlations with 4 measures of the frequency and intensity of interruptions (interruption rate, probability of unsuccessful attempts, probability of appropriation, and probability of agonistic behavior). Disperson of food and the proximity of neighboring baboons had little or no effect on the frequency or intensity of interruptions. Food quality had negligible effects on the probabilities of appropriation and agonistic behavior. Yield characteristics were the best predictors of the success of attempted interruptions: attempts were least likely to be successful when processing the food was time-consuming. These results suggest that (1) the interrupter decides whether to interrupt on the basis of increasing its probability of winning the contest and decreasing its cost, and (2) the victim decides whether to resist on the basis of the time that has been and must be invested in harvesting the contested food item.     

In situ evaluation of the genotoxic potential of the river Nile: I. Micronucleus and nuclear lesion tests of erythrocytes of Oreochromis niloticus niloticus (Linnaeus, 1758) and Clarias gariepinus (Burchell, 1822)

This study aimed to investigate the genotoxic potential of chemicals present along the course of the river Nile using frequencies of micronuclei (MN) and nuclear lesions (NL) in erythrocytes of Nile tilapia Oreochromis niloticus niloticus and African catfish Clarias gariepinus, as biomarkers. Results showed that most of the physicochemical parameters detected and heavy metal concentrations were significantly higher in the water collected from the estuaries of the river Nile compared to other sites of the upper Nile. The frequencies of MN and NL in peripheral blood erythrocytes of Nile tilapia and African catfish were significantly higher in estuary sites in Damietta and Rosetta compared to upper sites. The lowest level of genotoxicity was observed at two sites (Aswan and Kena), considered to be less contaminated. Our results suggested that higher frequencies of MN and NL determined at Damietta and Rosetta sites may be indicative of damage produced by pollutants in these areas. The most remarkable result was that MN and NL frequencies appear to be strongly related to water quality at different sites examined, indicating that MN frequencies may serve as a reliable biomarker for testing genotoxicity in situ. The positive correlation between MN and NL induction suggested that NL may be a useful complementary assay for genotoxicity analyses when fish are used as experimental animals. It was also found that seasonal variations in MN and NL frequencies might contribute to a better understanding of genotoxic responses in the field. The use of fish as indicator organisms for monitoring the presence of genotoxic-inducing contaminants in the environment seemed justified because the effects of exposure to a “complex mixture” such as river water were obtained. Nile tilapia appears to be a more suitable bioindicator species than African catfish in studying genotoxic chemical pollution in the river Nile attributed to a higher sensitivity.     

Food and feeding dynamics of the larval Antarctic fishNototheniops larseni

The feeding dynamics of larvae of the Antarctic fishNototheniops larseni were analyzed from data collected over three years in Bransfield Strait and adjacent waters (Antarctica). Seasonal feeding was examined from 1977/1978 (November–March). The diel feeding cycle was investigated during a 96 h station established in February 1976, while food selection was analyzed using larvae and zooplankton samples collected in February 1982. Hatching occurs in early spring, and larvae fed on eggs of calanoid copepods and on cyclopoid copepods. Copepod eggs were the principal food near the pack ice, and cyclopoids in open waters. Cyclopoids were the staple food in summer. Eggs of the Antarctic krillEuphausia superba were ingested selectively and formed major portions of the larval summer diet in neritic (Joinville Island) and oceanic (Elephant Island) spawning areas ofE. superba. In the fall, copepods predominated in the diets. Most abundant and most frequently ingested prey in summer and fall wereOncaea spp. Feeding commenced at dawn and continued at least until dusk. Krill eggs were taken chiefly during morning hours and egg incidence declined during the day, suggesting that eggs were ingested soon after spawning. Prey size at the onset of feeding was estimated as 0.130 to 0.330 mm. Size-selective feeding was evident in small larvae, while in larger larvae median prey length remained constant. High feeding incidence among yolk-sac larvae in spring, high overall feeding incidence in summer, and size-selective foraging of small larvae suggested favorable feeding conditions in the 1977/1978 season. Yolk-absorption times in Antarctic fish larvae vary on a scale of weeks and may be further retarded due to early feeding. Hence, year-to-year variability of yolk incidence inN. larseni indicated variable biotic environments of early feeding larvae rather than temporal shifts of hatching periods. As hatching periods are constant between years in contrast to the variable retreat of the pack ice and subsequent onset of the production cycle in space and time, maternal yolk reserves are probably utilized to compensate for such variations.     

Life cycle of <Emphasis Type="Italic">Carybdea marsupialis</Emphasis> Linnaeus, 1758 (Cubozoa,Carybdeidae) reveals metamorphosis to be a modified strobilation

Two types of metamorphosis occur in the life cycle of Carybdea marsupialis Linnaeus 1758 (Cubozoa, Carybdeidae). In addition to the metamorphosis described several times over, during which the entire polyp transforms into one medusa, we investigated a second type of metamorphosis which leaves a regenerative remnant. This mode of medusa formation seems to be derived from the strobilation known from Scyphozoa. Both types are described and the implications these results have on the idea about the origin of the class Cubozoa, are discussed.     

Population structure,mortality and growth of <Emphasis Type="Italic">Pinna nobilis</Emphasis> Linnaeus, 1758 (Mollusca,Bivalvia) at different depths in Moraira bay (Alicante,Western Mediterranean)

An investigation to characterize the causes of Pinna nobilis population structure in Moraira bay (Western Mediterranean) was developed. Individuals of two areas of the same Posidonia meadow, located at different depths (A1, −13 and A2, −6 m), were inventoried, tagged, their positions accurately recorded and monitored from July 1997 to July 2002. On each area, different aspects of population demography were studied (i.e. spatial distribution, size structure, displacement evidences, mortality, growth and shell orientation). A comparison between both groups of individuals was carried out, finding important differences between them. In A1, the individuals were more aggregated and mean and maximum size were higher (A1, 10.3 and A2, 6 individuals/100 m²; A1, x = 47.2 ± 9.9; A2, x = 29.8 ± 7.4 cm, P < 0.001, respectively). In A2, growth rate and mortality were higher, the latter concentrated on the largest individuals, in contrast to A1, where the smallest individuals had the higher mortality rate [A1, L = 56.03(1 − e^−0.17t ); A2, L = 37.59(1 − e^−0.40t ), P < 0.001; mean annual mortality A1: 32 dead individuals out of 135, 23.7% and A2: 16 dead individuals out of 36, 44.4%, and total mortality coefficients (z), z _A1(−30) = 0.28, z _A1(31–45) = 0.05, z _A1(46−) = 0.08; z _A2(−30) = 0.15, z _A2(31–45) = 0.25]. A common shell orientation N–S, coincident with the maximum shore exposure, was observed in A2. Spatial distribution in both areas showed not enough evidence to discard a random distribution of the individuals, despite the greater aggregation on the deeper area (A1) (A1, χ ² = 0.41, df = 3, P > 0.5, A2, χ ² = 0.98, df = 2 and 0.3 < P < 0.5). The obtained results have demonstrated that the depth-related size segregation usually shown by P. nobilis is mainly caused by differences in mortality and growth among individuals located at different depths, rather than by the active displacement of individuals previously reported in the literature. Furthermore, dwarf individuals are observed in shallower levels and as a consequence, the relationship between size and age are not comparable even among groups of individuals inhabiting the same meadow at different depths. The final causes of the differences on mortality and growth are also discussed.     

Food selectivity of the rotifer Brachionus plicatilis feeding on phytoplankton

Food selectivity was examined in amictic female rotifers, Brachionus plicatilis, fed Chlamydomonas sp. and Olisthodiscus sp. Filtering and ingestion rates of the rotifers in a single food suspension were higher with Chlamydomonas sp. than with Olisthodiscus sp. In every mixture of two food species, the apparent filtering rate on Chlamydomonas sp. was much higher than that on Olisthodiscus sp. Total filtering rate and apparent filtering rate in food suspensions containing Chlamydomonas sp. decreased with increasing cell concentration of Chlamydomonas sp. Total and apparent filtering rates were calculated from the decrease in total food concentration as well as from decreases in concentrations of each of the two food algae, respectively. B. plicatilis ingested Olisthodiscus sp. at an extremely low constant rate in all mixtures. The degree of food selectivity of the rotifers fed Chlamydomonas sp. (i.e., selective filtration) from the mixture of two food algae decreased with increasing cell concentration of Chlamydomonas sp. Filtering and ingestion rates of rotifers fed senescent Chlamydomonas sp. were relatively lower than those fed Chlamydomonas sp. in the exponential phase. This indicates that Brachionus plicatilis displays selectivity in regard to condition of cells as well as type of food.     

Swimming and feeding in Periphylla periphylla (Scyphozoa, Coronatae)

Some western Norwegian fjords host extraordinarily abundant and persistent populations of the mesopelagic, coronate scyphomedusa, Periphylla periphylla. In these environments, from late autumn to spring, the medusae undertake regular diel vertical migrations into surface waters. From unique observations obtained with a remotely operated vehicle (ROV), including observations made without artificial light, we observed that 90% of the medusae swam with their tentacles in aboral position. Stomach content analyses of surface-collected specimens revealed that the medusae ate mainly calanoid copepods, but ostracods and large euphausiids were also prominent components of their diets. The clearance rate potential of P. periphylla, assessed from in situ observations and stomach contents, was comparable to that of similar-sized, epipelagic gelatinous species. Our findings suggest that P. periphylla behave as active predators in surface waters.     

Trophic status and feeding selectivity of blennies (Blenniidae: Salariini)

An evaluation of the dietary resources available to, and selected by, blennies of the tribe Salariini was used to assess their trophic status on the Great Barrier Reef. Gut-content analysis of nine species of blennies found detrital aggregates to be the dominant item ingested. Samples of the dietary resources available to one of these species, Salarias patzneri, were compared biochemically. Of the two main dietary categories (detrital aggregates and filamentous algae), detrital aggregates were the major resource available, accounting for 53 ± 4.6% (SE) of the organic matter present. The mean C:N values for detrital aggregates (17.2 ± 0.8) and filamentous algae (20.0 ± 1.8) were very similar, as were protein concentrations (1.8 ± 0.1 and 2.1 ± 0.1 μg mg⁻¹, respectively). However, mean carbohydrate concentrations were much lower in the aggregates than the filamentous algae (19 ± 2 and 76 ± 13 μg mg⁻¹, respectively). Comparison of the inorganic particles ingested to those available indicated that S. patzneri selectively fed on particles <125 μm, (predominantly detrital aggregates) and avoided particles >250 μm, (predominantly algal filaments). The patterns of resource availability, nutritional quality and selectivity suggest that salariin blennies utilise detrital aggregates as their primary dietary resource. Received: 24 May 1999 / Accepted: 29 November 1999     

Nutrients uptake and growth of Ulva lactuca (Linnaeus, 1753) in grey mullet (Mugil cephalus) wastewater versus natural estuarine water

This study investigates the capability of Ulva lactuca to grow in an integrated system, aiming to optimise the needing of resources and to decrease the ecological impact of wastewater. The nutrients uptake and the growth of U. lactuca in Mugil cephalus wastewater (WW) were evaluated and compared with U. lactuca cultivated in estuarine water (EW). Fresh thalli of U. lactuca were cultivated for 10 days in 5?L cylindrical tanks, 3 replicates per treatment. The uptake of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP), as well as the biomass yield and specific growth rate of U. lactuca, were assessed every two days. At the end of the experiment, U. lactuca resulted in a higher assimilation of DIN in EW (95.7?±?0.3%, mean?±?SE) than in wastewater (68.7?±?1.0%) (p?80%), as well as in the biomass yield and specific growth rate. This study demonstrates the efficiency of U. lactuca in the assimilation of DIN and DIP from M. cephalus WW, contributing to reduce the release of dissolved inorganic nutrients in the natural environment.     

Functional morphology and feeding behavior of Scolelepis squamata (Polychaeta: Spionidae)

Functional morphology and feeding behavior of Scolelepis squamata (Müller) were studied. Gut contents consisted of unconsolidated sedimentary particles, fecal pellets of other species, and a wide variety of embryos, larvae, and juveniles. Unlike other spionid polychaetes the palps of S. squamata lack a median, ciliated groove. Particles captured by the palps were brought to the pharynx by a complete contraction of the palp. In the presence of a current, S. squamata helically coiled their palps, and fed almost exclusively on suspended and resuspended particles. In contrast to most spionid polychaetes the palps of S. squamata are not deciduous. Various aspects of the morphology and feeding behavior of S. squamata are discussed in terms of their functional and ecological significance.     

Ultra-structural observations on the lymphoid organs of the freshwater catfish, Clarias batrachus (Linnaeus)

Light microscopic and ultra-structural studies of the lymphoid tissues such as blood immunocytes, spleen and pronephros of the freshwater catfish, Clarias batrachus, were carried out. The peripheral blood showed nucleated erythrocytes, total leucocytic count (TLC) more than that observed in mammalian blood and leucocytes with morphological appearance similar to the mammalian white blood cells (WBCs). The spleen and pronephros showed presence of numerous lymphocytes, monocytes and nucleated red blood cells (RBCs) along with hemosiderin-containing macrophages. The morphology of lymphoid organs of the catfish has been discussed in light of the evolution of the immune system in this class of vertebrates.     

Functional morphology and feeding behavior of Paraprionospio pinnata (Polychaeta: Spionidae)

The functional morphology and feeding behavior of Paraprionospio pinnata (Ehlers) were studied. The tentacular feeding palps of P. pinnata possess four groups of cilia: laterals, latero-frontal cirri, frontals and basal transverse rows. The lateral cilia beat in metachronal waves creating in current that flows toward the frontal surface of the palp. The latero-frontal cirri deflect suspended particles onto the frontal surface and potentially resuspend deposited particles. The frontal cilia line the groove of the palp and transport particles to the ciliated pharynx. The basal transverse cilia also beat in metachronal waves and together with the frontal cilia of the branchiae produce a U-shaped current that removes particles rejected by the pharynx from the burrow. The significance of particle selection at the site of the pharynx in spionid polychaetes is hypothesized to be constrained by the interaction of specific morphologies and behaviors that reduce the effects of epifaunal predation and browsing. The relationship between sediment permeability and type of respiratory or ventilation current is hypothesized to be a potentially important factor in understanding the distribution of spionid polychaetes.     

Form and feeding mechanism of a living Planctosphaera pelagica (phylum Hemichordata)

We describe aspects of the anatomy and suspension-feeding mechanism of a single Planctosphaera pelagica captured from the plankton in June 1992 off Bermuda in the western Atlantic. We also describe several unusual features of the larva, including its occurrence in surface waters, unusually large size, and limited swimming ability. Our account of the form and feeding behavior of P. pelagica is the first based on observations of a specimen captured and observed alive. Our limited observations suggest that the planctosphaera may use a suspension-feeding mechanism much like that of the other feeding deuterostome larvae (the pluteus and bipinnaria larvae of echinoderms and the tornaria larva of enteropneust hemichordates) known to capture food particles using a single ciliated band. Although we could not observe cilia directly, the movement of dye streams and food particles and the structure of the ciliated band suggest that some particles may be captured at the ciliated band by the reversal of ciliary beat. The planctosphaera possesses many prominent mucous glands near the food grooves. This suggests an important role of mucus in the biology of the larva, but we were not able to observe directly any role of mucus in particle capture.     

On the feeding of Branchiostoma senegalense (Acrania: Branchiostomidae)

The feeding biology of Branchiostoma senegalense Webb from the North-West African shelf region off Mauritania was investigated. The hindgut contained almost exclusively seston components, ranging in size from less than 1 m (bacteria size) to 300 m. Numerous chloroplasts of ingested phytoplankton appeared to be undigested. Dunaliella salina was still alive when leaving the anus after 1 to 2 h. Detritus formed the greater part of the gut contents. The authors conclude that the lancelets feed mainly on detritus and thus are indiscriminate suspension feeders.     

Comparison of the feeding habits of migratory and non-migratory Stenobrachius leucopsarus (Myctophidae)

Stenobrachius leucopsarus, the most abundant species of myctophid fishes off Oregon, USA, has a bimodal distribution at night, with a peak of abundance in the upper 100 m composed of diel vertical migrants, and another peak at 300 to 500 m composed of fish that did not migrate the night they were caught. We compared the feeding habits of these two groups of fish in an attempt to learn if deep fish migrated to surface waters. Low similarity of diets, differences in the rank order of common prey, and similar states of stomach fullness and digestion of prey suggest that fish captured in deep water at night probably did not feed exclusively in shallow water on previous nights. They probably fed in deep water. The similarity in food habits between deep and shallow fish is most readily explained by daytime feeding by fish in deep water and by broad vertical distributions of prey.