Female discharges are more electrifying: spontaneous preference in the electric fish,Eigenmannia (Gymnotiformes,Teleostei)

Summary The tropical South American teleost Eigenmannia lineata showed a spontaneous preference for the female type, compared with the male type, of its sexually dimorphic, weak-electric organ discharge (EOD). Female and male EODs differ in waveform and harmonic content. An isolated fish was simultaneously stimulated with digitally synthesized natural male and female EODs of equal peak-to-peak amplitudes, at ±35 Hz frequency difference centered on its stable resting discharge frequency. The stimulus dipoles were arranged symmetrically to the right and left of the fish's hiding place. All stimulus conditions were permuted at random sequence. Among 11 fish tested, 8 showed a statistically significant preference for one stimulus, the female type, as measured by the amount of time a fish spent close to a stimulus dipole (P<0.05 in each fish, two-tailed). Thus female EODs rather than male EODs were more attractive to adult and juvenile fish of both sexes. It was also concluded that E. lineata is capable of discriminating female from male EODs by a complex sensory capacity requiring neither amplitude nor frequency cues. The EOD waveform changed very little within the ecological range of water conductivities (approximately 10–100 S·cm^-1); the P/N-ratio (a waveform character based on zerocrossing intervals) depended only weakly, but significantly, on conductivity (negative correlation in all four fish). Also, the effect of temperature on EOD waveform was very weak: Q ₁₀-values of the P/N-ratio were below but close to 1 in all fish (27±5°C). Thus, it can be concluded that the EOD waveform is remarkably stable within widely changing conditions-even beyond the variation found in the field-and is therefore potentially useful as a social cue.     

Electrosensory basis for individual recognition in a weakly electric, mormyrid fish, Pollimyrus adspersus (Günther, 1866)

Pollimyrus adspersus discriminates the individually variable waveforms of Electric Organ Discharges (EODs) of conspecifics of only 150–250 s duration. We examined: (1) the discrimination threshold for artificially generated EODs of similar waveform, (2) the mechanism of signal analysis (spectral vs temporal) present, by determining the discrimination between different waveforms of identical amplitude spectra, and (3) the threshold field intensity and reach of discrimination. The triphasic P. adspersus EOD waveform was artificially generated by superimposing two Gaussians, one wide, the second narrow, inverted, and of threefold amplitude. The natural variability among individual EOD waveforms was simulated by phase-shifting one Gaussian relative to the other. The symmetrical waveform where the peaks of the two Gaussians coincided was used as a reference (phase shift=0, rewarded stimulus S+). Results were: (1) in food-rewarded conditioning experiments, trained fish (N=7) detected a phase-shift in artificial EOD stimuli as low as 2 s (N=2 fish), 6 s (N=1) and 10 s (N=1). (2) All fish tested (N=3) discriminated between artificial EODs of identical amplitude spectra but different waveforms (hence, different phase spectra), demonstrating a temporal mechanism of signal analysis. (3) The maximum reach of waveform discrimination was 130 cm at 4.9 V_p-p/cm and 100 S/cm water conductivity (test signal generated at natural amplitude), that is, similar to the reach of EOD detection. Therefore, among the three kinds of electroreceptor organ present in mormyrids, we consider Knollenorgane the relevant sensory organs for EOD waveform discrimination.Communicated by J. Krause     

A comparative study of the toxicity of lead and its impact on the carbohydrate metabolism and some haematological parameters of cichlid fish,oreochromis niloticus and catfish,clarius gariepinus from saudi arabia

Fresh and healthy specimens of Oreochromis niloticus (mean weight 70.5± 1.23 g and mean length, 12.3± 1.5cm) and Clarias gariepinus (mean weight, 41.8±2.3 g and mean length 13.78 ± 1.2 cm) were exposed to heavy metal lead, ranging in concentration from 10 to 18 mg L^‐1 for O. niloticus and 20 to 28 mg L^‐1 for C. gariepinus respectively. The 96 h LC₅₀ for both the species was computed as 12.45 mg L^‐1 (O. niloticus) and 22.65 mg L^‐1 (C. gariepinus). The cichlid fish was exposed to sublethal concentration of lead (2, 4 and 6 mgL^‐1) and catfish (4, 8 and 12 mgL^‐1). The erythrocytes count, haemoglobin concentration, haematocrit and the value of serum glucose increased significantly (P < 0.01), whereas leucocytes count, serum protein and serum triglyceride after intoxication declined in both the species with the same pattern but in different quantity. After 96 h of time a significant depletion of muscle and liver glycogen was noted, being greater in muscle (16.7% in O. niloticus) and in liver (15.9% in C. gariepinus). The response of fish to lead was dose dependent.     

Male signaling behavior and sexual selection in a wolf spider (Araneae: Lycosidae): a test for dual functions

Male signaling behaviors are often studied in a single context but may serve multiple functions (e.g., in male–male competition and female mate choice). We examined the issue of dual function male signals in a wolf spider species Schizocosa ocreata (Hentz) that displays the same species-specific signaling behaviors in both male–male and male–female contexts. These signaling behaviors have been described as either aggression or courtship according to the context observed. We tested the possibility of dual functions by comparing the relationship between behaviors and outcome of male–male contests (winner/loser) and male–female mating encounters (mating success). Frequency, rate, and mean duration of signaling behaviors did not vary with outcome of male–male contests, which appears instead to be based upon relative size and body mass. Winners of contests had significantly greater body mass than losers, and greater mass relative to opponents was significantly associated with probability of winning. Overall, signaling rates were much higher in male–female interactions than in male–male contests and were higher for males that successfully mated than for those that did not mate. Mean duration of some male displays was also greater for males that successfully mated. However, male size was not associated with probability of mating. Taken together, results suggest an intersexual selection context for the current function of male signals in these wolf spiders and that increased display vigor is associated with male mating success.     

Echolocation and foraging behavior of the lesser bulldog bat, Noctilio albiventris : preadaptations for piscivory?

We studied variability in foraging behavior of Noctilio albiventris (Chiroptera: Noctilionidae) in Costa Rica and Panamá and related it to properties of its echolocation behavior. N. albiventris searches for prey in high (>20 cm) or low (<20 cm) search flight, mostly over water. It captures insects in mid-air (aerial captures) and from the water surface (pointed dip). We once observed an individual dragging its feet through the water (directed random rake). In search flight, N. albiventris emits groups of echolocation signals (duration 10–11 ms) containing mixed signals with constant-frequency (CF) and frequency-modulated (FM) components, or pure CF signals. Sometimes, mostly over land, it produces long FM signals (duration 15–21 ms). When N. albiventris approaches prey in a pointed dip or in aerial captures, pulse duration and pulse interval are reduced, the CF component is eliminated, and a terminal phase with short FM signals (duration 2 ms) at high repetition rates (150–170 Hz) is emitted. Except for the last pulses in the terminal phase N. albiventris avoids overlap between emitted signals and echoes returning from prey. During rakes, echolocation behavior is similar to that in high search flight. We compare N. albiventris with its larger congener, N. leporinus, and discuss behavioral and morphological specializations that can be interpreted as preadaptations favoring the evolution of piscivory as seen in N. leporinus. Prominent among these specializations are the CF components of the echolocation signals which allow detection and evaluation of fluttering prey amidst clutter-echoes, high variability in foraging strategy and the associated echolocation behavior, as well as morphological specializations such as enlarged feet for capturing prey from the water surface. Received: 21 April 1997 / Accepted after revision: 12 January 1998     

In situ ontogeny of behaviour in pelagic larvae of three temperate, marine, demersal fishes

The ontogeny of behaviour relevant to dispersal was studied in situ with reared pelagic larvae of three warm temperate, marine, demersal fishes: Argyrosomus japonicus (Sciaenidae), Acanthopagrus australis and Pagrus auratus (both Sparidae). Larvae of 5–14 mm SL were released in the sea, and their swimming speed, depth and direction were observed by divers. Behaviour differed among species, and to some extent, among locations. Swimming speed increased linearly at 0.4–2.0 cm s⁻¹ per mm size, depending on species. The sciaenid was slower than the sparids by 2–6 cm s⁻¹ at any size, but uniquely, it swam faster in a sheltered bay than in the ocean. Mean speeds were 4–10 body lengths s⁻¹. At settlement size, mean speed was 5–10 cm s⁻¹, and the best performing individuals swam up to twice the mean speed. In situ swimming speed was linearly correlated (R ²=0.72) with a laboratory measure of swimming speed (critical speed): the slope of the relationship was 0.32, but due to a non-zero intercept, overall, in situ speed was 25% of critical speed. Ontogenetic vertical migrations of several metres were found in all three species: the sciaenid and one sparid descended, whereas the other sparid ascended to the surface. Overall, 74–84% of individual larvae swam in a non-random way, and the frequency of directional individuals did not change ontogenetically. Indications of ontogenetic change in orientated swimming (i.e. the direction of non-random swimming) were found in all three species, with orientated swimming having developed in the sparids by about 8 mm. One sparid swam W (towards shore) when <10 mm, and changed direction towards NE (parallel to shore) when >10 mm. These results are consistent with limited in situ observations of settlement-stage wild larvae of the two sparids. In situ, larvae of these three species have swimming, depth determination and orientation behaviour sufficiently well developed to substantially influence dispersal trajectories for most of their pelagic period.     

Potential mechanisms for the communication of height and distance by a stingless bee, Melipona panamica

This study investigates the recruitment communication mechanisms of a stingless bee, Melipona panamica, whose foragers can evidently communicate the three-dimensional location of a good food source. To determine if the bees communicate location information inside or outside the nest, we conducted removal experiments by training marked foragers to one of two identical feeders and then separating these experienced foragers from potential recruits as they left the nest. The feeders were positioned to test the communication of each dimension. The results show that recruits do not simply follow experienced foragers to the food source. Height and distance are communicated within the nest, while direction is communicated outside the nest. We then examined the pulsed sounds produced by recruiting foragers. While unloading food, recruiting foragers produced several short pulses and one or more very long pulses. On average, the longest unloading pulse per performance was 31–50% longer (P ≤ 0.018) for bees foraging on the forest floor than for bees foraging at the top of the forest canopy (40 m high). While dancing, recruiting foragers produced sound pulses whose duration was positively correlated with the distance to the food source (P < 0.001). Dancing recruiters also produced several short sound pulses followed by one or more long pulses. The longest dance pulse per performance was 291 ± 194 ms for a feeder 25 m from the nest and 1858 ± 923 ms for a feeder 360 m away from the nest. The mechanism of directional communication remains a mystery. However, the direction removal experiment demonstrates that newcomers cannot use forager-deposited scent marks for long-distance orientation (>100 m from the nest). Received: 25 September 1997 / Accepted after revision: 31 May 1998     

Population biology and life strategies of Chlorophthalmus agassizii Bonaparte, 1840 (Pisces: Osteichthyes) in the Mediterranean Sea

The population biology and life strategies of Chlorophthalmus agassizii were studied in the Ionian Sea (eastern–central Mediterranean) using the data collected during the experimental trawl surveys carried out from 1995 to 2000. Depth-related trends of both density and size were found. With depth the former decreased while the latter increased. A typical bigger–deeper phenomenon was detected: young-of-the-year individuals occur on the shelf during autumn–winter months and move towards bathyal bottoms as they grow. The sampled population was made up of several size–age groups. The maximum age of 8 years was identified by means of otolith readings. The Von Bertalanffy growth parameters were estimated from the age–length key (L _∞=189.04±5.401 mm; k=0.24±0.021; t _o=−1.20±0.132; φ′=3.94) and modal progression analysis (L _∞=218.33±18.397 mm; k=0.164±0.028; t _o=−1.694±0.171; φ′=3.89). Reproduction of this monoecious fish was observed during summer–early autumn. Considering the female portion of the gonad, the size at attainment of 50% maturity was 115 mm TL. The corresponding age is within the third year of life. The simultaneous occurrence of oocytes in different development stages was shown in the ovary. Both the asynchronous ovary and oocyte size distribution indicate that C. agassizii spawns more than once during a reproductive season (batch spawner). Functional fecundity (on average 3,018 hydrated oocytes) was between 37 and 69% of the absolute fecundity and increased significantly with the individual size. Since adult specimens are mostly distributed on the slope, eggs and larvae develop in epipelagic waters and migrate in-shore where juvenile forms recruit on the shelf. Juveniles migrate ontogenetically towards deeper bottoms and after 2–3 years start to reproduce annually within a life span greater than 10 years.     

Patterns of the electric organ discharge during courtship and spawning in the mormyrid fish,Pollimyrus isidori

Summary Pollimyrus isidori's electric organ discharge (EOD) is of the pulse type. Patterns of EOD intervals were investigated prior to, during and following spawning behaviors as related with overt behaviors, and with the sound production by the nestbuilding male. Prior to the time of reproduction, isolated and socially interacting fish (n=15) showed characteristic discharge interval patterns for resting, swimming, probing, hovering and hiding activities. Males (n=8) and females (n=6) did not differ in their mean EOD repetition rates during resting (11.6±2.5 Hz), nor Short Bursts/min (less than 20 intervals of 8–13 ms). In interacting fish Long Bursts (greater than 20 intervals of 8–13 ms, lasting for more than 300 ms) were observed only during the attack and bite sequence. A pursuing fish displayed a rapid alternation of Long Bursts with Discharge Breaks (300–1000 ms silence) during the chase behavior. Avoidance behavior which followed from several attacks was correlated with a Medium Uniform Rate (8–12 Hz) normally lasting for 20 to 60 s, or a Discharge Arrest (silence greater than 1 s) in the submissive fish. The nocturnal courtship behavior began soon after dark (1900 h). Spawning typically started 2 to 5 h after dark, continuing for 2 to 6 h until about 0200 h. During courtship and spawning the female's brief visits (15–25 s) to the male's territory recurred every 30–60 s. At all other times the female was aggressively excluded from the nest region. Courtship and spawning behaviors are described along with the electrical displays identified from 19 spawnings in three fish pairs (from a total of 37 spawnings in 4 males and 4 females). Just prior to the onset of courtship behavior, with male territorial aggression beginning to decline, females switched from a Medium Sporadic Rate pattern (resting and hiding patterns; 13 Hz) to a Medium Uniform Rate pattern (6–8 Hz) while still in their hiding area. Females continued to display this uniform rate throughout the courship and spawning period, including the courtship and spawning bouts when Discharge Breaks or Arrests also occurred. This persistance distinguishes the courtship pattern from the similar avoidance pattern (see above). The male courtship and spawning EOD pattern was similar to the female's and unique for a territorial male. He switched from a High Sporadic Rate (swimming EOD pattern; about 18 Hz) to a regularized Medium Uniform Rate (about 9 to 11 Hz) only during courtship and spawning bouts, including 1–3 EOD Breaks during Vent-to-Vent coupling (average interval: 272±71 ms, n=37). No sooner had the female left the spawning site than he resumed displaying a High Sporadic Rate. This temporal correlation of reproductive behaviors with electrical displays suggests their instrumental role in mutual acceptance of mates. Males showed their sex-specific type of EOD phase-locking, the Preferred Latency Response, only during the first few hours of entry of a fish in their tank. Two females with EOD waveform features more typical of males also spawned repeatedly; waveform does not appear to be critical. Males stopped their nocturnal sound production for the later part of courtship and the whole spawning period. Except for infrequent attacks on the female between spawning bouts, the male did not resume singing until the end of spawning when all eggs were shed (around 0200 h); from this time on the male sang until dawn. The sequencing of the three acoustic elements (moans, grunts, growls) are described. A catalogue of discharge patterns correlated with overt behaviors (Tables 1, 2), and an integrated summary time table of P. isidori's complex reproductive behavior are presented.     

Distributional patterns of adult male loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) in the vicinity of Cape Canaveral,Florida, USA during and after a major annual breeding aggregation

Satellite transmitters were attached to 25 reproductively active and four inactive adult male loggerhead sea turtles (86.6–107.0 cm SCLmin) captured from the Port Canaveral, FL, USA shipping channel to assess horizontal and vertical distributions. During the breeding period, male loggerheads aggregated (44% of 755 turtle days) in a 117.6 km² core area that encompassed the shipping channel. Median dive duration during the breeding period was 27 min (IQR = 15–42 min) and males spent 4% (IQR = 3–5%) of the time at the surface, with significantly shorter dives associated with reproductively active males. Migrant and resident males dispersed concurrently, with residents shifting > 30 km east across the continental shelf over a more protracted departure schedule than migrants. Dive duration and time spent at the surface increased through the fall. Cluster analysis revealed the strongest association for dive duration with sea state during and after the breeding period, with significantly longer dives during more turbulent conditions. In contrast, univariate associations with surface interval duration were not elucidated.     

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.     

Size-dependent photosynthetic performance in the giant clam <Emphasis Type="Italic">Tridacna maxima</Emphasis>, a mixotrophic marine bivalve

Giant clams form a symbiosis with photosynthetic algae of the genus Symbiodinium that reside in clam mantle tissue. The allometry of symbiont photosynthetic performance was investigated as a mechanism for the increasing percentage of giant clam carbon respiratory requirements provided by symbionts as clam size increases. Chlorophyll fluorescence measurements of symbionts of the giant clam Tridacna maxima were measured during experiments conducted in September of 2009 using specimens 0.5–200 g tissue wet weight (3–25 cm long), collected from waters around southern Taiwan (N 21°36′, E 120°47′) from July to August of 2009. Light-dependent decreases in effective quantum yield (∆F/F _m′) calculated as the noontime maximum excitation pressure over PSII (Q _m), relative electron transport rates (rETR), and dark-adapted maximum quantum yield (F _v/F _m) all varied as a quadratic function of clam size. Both Q _m and rETR increased as clam size increased up to ~10–50 g then decreased as clam size increased. F _v/F _m decreased as clam size increased up to ~5–50 g then increased as clam size increased. Chlorophyll fluorescence measurements of rETR were positively correlated with gross primary production measured during chamber incubations. Overall, symbionts of mid-sized clams ~5–50 g exhibited the highest light-dependent decreases in effective photosynthetic efficiencies, the highest relative electron transport rates, and the lowest maximum photosynthetic efficiencies, and symbiont photosynthetic performance is allometric with respect to host clam size.     

Population dynamics,reproduction and growth of the Indo-Pacific horned sea star, <Emphasis Type="Italic">Protoreaster nodosus</Emphasis> (Echinodermata; Asteroidea)

The horned sea star (Protoreaster nodosus) is relatively common in the Indo-Pacific region, but there is little information about its biology. This study of the population biology of P. nodosus was carried out in Davao Gulf, The Philippines (7°5′N, 125°45′E) between September 2006 and May 2008. Protoreaster nodosus was found in sand and seagrass dominated habitats at a mean density of 29 specimens per 100 m² and a mean biomass of 7.4 kg per 100 m², whereas a significantly lower density and biomass was found in coral and rock dominated habitats. Adult specimens (mean radius R = 10.0 cm) were found at depths of 0–37 m, whereas juveniles (R < 8 cm) were only found in shallow sandy habitats with abundant seagrass (water depth ≤2 m). Increased gonad weights were found from March to May (spawning period), which coincided with an increasing water temperature and a decreasing salinity. Density and biomass did not change significantly during reproduction, but sea stars avoided intertidal habitats. All specimens with R > 8 cm had well developed gonads and their sex ratio was 1:1. Protoreaster nodosus grew relatively slowly in an enclosure as described by the exponential function G = 7.433 e^{−0.257 × R} . Maturing specimens (R = 6–8 cm) were estimated to have an age of 2–3 years. Specimens with a radius of 10 cm (population mean) were calculated to have an age of 5–6 years, while the maximum age (R = 14 cm) was estimated as 17 years. Potential effects of ornamental collection on the sea star populations are discussed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Aluminium in tea plantations: mobility in soils and plants, and the influence of nitrogen fertilization

The levels of extractable aluminum (Al) in soils of tea plantations, Al concentrations in tea leaves and the impact of nitrogen fertilization on these two parameters were investigated. In addition, the properties of soils from tea plantations were compared to those from soils of adjacent non-tea fields to evaluate the effect of land use conversion (from non-tea soils to tea soils). Exchangeable Al (extracted in 1 mol l⁻¹ KCl) ranged from 0.03 to 7.32 cmol_c kg⁻¹ in 94 tea fields and decreased rapidly with increasing soil pH. In comparison with non-tea soils, tea soils had a significantly lower pH and exchangeable Mg²⁺ concentration but higher organic matter contents and exchangeable K⁺ concentration. Contents of extractable Al were not different (P > 0.05) between these two soils. The concentrations of Al in mature tea leaves correlated significantly with exchangeable Al in soil samples taken at a depth of 20–40 cm and with exchangeable Al saturations in soil sampled at␣depths of 0–20 and 20–40 cm. In the pot experiment, nitrogen fertilization significantly increased extractable Al levels but decreased soil pH and the levels of exchangeable base cations. Nevertheless, the levels of Al in mature leaves and young shoots were significantly reduced by the application of large amounts of N fertilizer.     

Arsenic mineralization,source, distribution,and abundance in the Kutahya region of the western Anatolia,Turkey

Environmental exposure to arsenic (As) in the Kutahya region of the western Anatolia, Turkey has been reported to cause various types of arsenic-associated skin disorders (Dogan, Dogan, Celebi, & Baris, 2005). A geological and mineralogical study was conducted to find the sources and distribution of the As. Geogenic (background) levels were measured in samples collected from various sources in the Gediz, Simav, Tavsanli, Emet, Yoncali, Yenicekoy, and Muratdagi areas of the Kutahya region. Based on this analysis, we determined that natural sources are a domineering factor affecting the distribution of As, which was found: (1) mainly in evaporitic minerals, including colemanite (269–3900 ppm) and gypsum (11–99,999 ppm), but also in alunite (7–10 ppm) and chert (54–219 ppm); (2) in secondary epithermal gypsum, which has a high concentration of As in the form of realgar and orpiment along fracture zones of Mesozoic and Cenozoic carbonate aquifers; (3) in rocks, including limestone/dolomite (3–699 ppm) and travertine (5–4736 ppm), which are relatively more enriched in As than volcanics (2–14 ppm), probably because of secondary enrichment through hydrological systems; (4) in coal (1.9–46.5 ppm) in the sedimentary successions of the Tertiary basins; (5) in thermal waters, where As is unevenly distributed at concentrations varying from 0.0–0.9 mg/l. The highest As concentrations in thermal water (Gediz and Simav) correlate to the higher pH (7–9.3) and T (60–83°C) conditions and to the type of water (Na–HCO₃–SO₄ with high concentration of Ca, Mg, K, SiO₂, and Cl in the water). Changes in pH can be related to some redox reactions, such as the cation exchange reactions driving the dissolution of carbonates and silicates. Fe-oxidation, high pH values (7–9.3), presence of other trace metals (Ni, Co, Pb, Zn, Al), increased salinity (Na, Cl), high B, Li, F, and SiO, high Fe, SO₄ (magnetite, specularite-hematite, gypsum), and graphite, and the presence of U, Fe, Cu, Pb, Zn, and B, especially in the Emet, Gediz, and Simav areas, are the typical indicators for the geothermally affected water with high As content. A sixth source of As in this region is the ground (0.0–10.7 mg/l) and the surface waters (0.0022–0.01 mg/l), which are controlled by water–rock interaction, fracture system, and mixing/dilution of thermal waters. The high As concentration in groundwater corresponds to the areas where pathological changes are greatest in the habitants. Arsenic in ground water also effects ecology. For example, only Juriperus oxycedrus and J. varioxycedrus types of vegetation are observed in locations with the highest concentration of As in the region. Branches and roots of these plants are enriched in As.     

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.     

Variation in pelagic larval growth of Atlantic billfishes: the role of prey composition and selective mortality

Atlantic blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) larvae were collected from 10 monthly cruises (June–October 2003 and 2004) across the Straits of Florida to test (1) whether growth differed between the more productive western region near the Florida shelf, and the less productive eastern region toward the Bahamas, and (2) whether growth was related to prey consumption. Examination of larval sagittal otoliths revealed that instantaneous growth and daily growth during the first 2–3 weeks of life did not vary significantly between the two regions for either species. However, recent growth during the last two full days prior to collection was greater in the west for blue marlin larvae. Recent growth of blue marlin larvae <9 mm SL (primarily zooplanktivorous) was significantly related to prey composition (faster growth when higher proportions of Farranula copepods were consumed). Western larvae grew faster and had higher proportions of Farranula in their guts. Trends for sailfish larvae were not significant. In both species, comparison of early growth between <9 and ≥9 mm SL size groups indicated that growth trajectories diverged around 5–8 mm SL, the time when billfish larvae become capable of piscivory. Significantly faster growth of larger (older) larvae suggests that mortality was selective for fast growers and that the transition to piscivory may be a critical point in the early life of billfish.     

Extraction of Co,Ni, Cu,Zn and Cd ions using 2-aminophenylaminopropylpolysiloxane

Insoluble porous solid functionalized ligand system bearing 2-aminophenylaminopropyl chelating ligand of the general formula P–(CH₂)₃NH–(C₆H₄)–NH₂ was prepared via the sol–gel process, where P represents [Si–O] _n polysiloxane network. First, the 2-aminophenylaminopropylsilane agent was prepared by substitution reaction between 3-chloropropyltrimethoxysilane and 1,2-phenylenediamine, followed by hydrolytic polycondensation between 2-aminophenylaminopropylsilane agent and tetraethylorthosilicate(TEOS). The immobilized 2-aminophenylaminopropylpolysiloxane P–(CH₂)₃NH–(C₆H₄)–NH₂(P–AphA) was characterized by ¹³C NMR, XPS, and FTIR. The results showed that 1,2-phenylenediamine groups were introduced onto polysiloxane network. The functionalized ligand system exhibits 90–100% metal uptake capacity for all metal ions except Cd²⁺. The elemental analysis data and the metal uptake capacities of the immobilized ligand system suggest that over than 90% ligand sites were involved in coordination with metal ions except that of cadmium forming 1:1 metal to ligand ratio complexes.     

Assessment of acute toxicity of ��-cyhalothrin to a freshwater catfish, Clarias batrachus

Acute static bioassays were conducted for 96 h period with λ-cyhalothrin to determine its acute toxicity to a freshwater catfish, Clarias batrachus. The 96 h LC₅₀ value was estimated to be 5.00 μg l⁻¹ (95% confidence limit: 4.114–5.712). The alterations in behavioral pattern, such as change in the color of skin, hyperactivity, loss of balance, rapid swimming, increased surfacing activity, enhanced rate of opercular activity, as well as prominent rates of convulsions in treated fish were observed with the increasing concentrations of insecticide as compared to the control fish. The results indicate that λ-cyhalothrin is highly effective even at very low concentrations.     

Temporal variation in protein, carbohydrate, and lipid concentrations in Paramuricea clavata (Anthozoa, Octocorallia): evidence for summer–autumn feeding constraints

Temporal variations in protein, carbohydrate, and lipid levels were studied in a passive suspension feeder, the gorgonian Paramuricea clavata. The samples were collected every month for mature and immature colonies over a three-year period (1997–2000). The relationship between biochemical composition and reproductive output was examined on the basis of the 1998 and 1999 data. In female and male P. clavata colonies, the tissue displayed differences in lipid concentrations only in winter–spring, due to the high lipid levels attained by female colonies in this period. Immature colonies showed significant differences in lipid concentration only with respect to mature females in spring. There were clear seasonal trends in the lipid and carbohydrate levels in P. clavata, with maximum values in winter–spring [male lipid 212±75 SD μg mg⁻¹ of organic matter (OM) and female lipid 274±103 SD μg mg⁻¹ of OM; male and female carbohydrate 68±14 SD μg mg⁻¹ of OM], coinciding with maximum food concentration/quality, and minimum values in summer–autumn (male and female lipid 155±57 SD μg mg⁻¹ of OM; male and female carbohydrate 56±14 SD μg mg⁻¹ of OM), coinciding with low food concentration/quality. The relationship between reproductive output and tissue concentrations of lipids, carbohydrates, and proteins was not straightforward, although there was an evident overlap of the lipid accumulation and the gonadal development. The results of this study show that protein, carbohydrate, and lipid levels may provide a record of episodes in the ecological cycle bearing on the trophic aspects of the target species. The results indicate that information on seasonal biochemical levels may explain benthopelagic coupling processes, provided factors such as natural diet, feeding rates, reproduction, and growth are well understood.