Early life histories in the bryozoan<Emphasis Type="Italic"> Schizobrachiella sanguinea</Emphasis>: a case study

Mediterranean populations of Schizobrachiella sanguinea seem to span a wide range of contrasting benthic habitats. We have studied adult, larval, and recruit populations of S. sanguinea from sublittoral (approximately 10 m depth) communities at Blanes (Spain, NW Mediterranean). At the study site, the species colonises semi-obscure caves and, to a lesser extent, communities of sciaphilic algae. Our first goal was to show the periods of brooding, larval release, and recruitment. Plankton was collected about twice a week between July 1998 and June 2000 over an artificial reef. A total of 303 larvae were collected in 23 of the 102 days of sampling. At the study site the species shows a single, annual larval release period, which occurs from late March to June–July every year. Recruits were found from late May to late August 1999 and in late May 2000. A recruitment peak was observed in July 1999 and again in late May 2000. The presence of brooding adults corresponded to the periods of larval supply and recruitment. Our second goal was to investigate the causes of the variable distribution of the species along several communities in the north-west Mediterranean Sea. We describe adult distribution and the dynamics of larval supply, recruitment of early (15 days from settlement) and late (4 months from settlement) recruits. Patterns of larval presence and early recruit distribution along the communities on the reef did not reflect the adult distributions, whereas this was closely matched by the distribution of late recruits. Post-recruitment mortality strongly affected recruits of the PA (photophilic algae) and SA (sciaphilic algae) communities, whereas it was very low in the communities of SOC (semi-obscure caves). Mortality of recruits was density independent and colony survivorship in the SA communities, where recruitment was the highest, appeared strongly affected by competition with brown algae. Like the majority of cheilostomate bryozoans, S. sanguinea releases a coronate larva capable of active swimming and positive reaction to light. Such swimming abilities may allow larvae to actively select the substrate on which to settle and to avoid unsuitable substrates. It seems that larval behaviour does not explain the preference of S. sanguinea for sciaphilic habitats. High post-recruitment mortality due to various factors, especially competition with fast-growing algae, seems particularly relevant in determining the adult distributions observed.Communicated by S.A. Poulet, Roscoff     

The gametogenic cycle of<Emphasis Type="Italic"> Octopus vulgaris</Emphasis> (Mollusca: Cephalopoda) as observed on the Atlantic coast of Andalusia (south of Spain)

The present study reports the gametogenic cycle of the common octopus, Octopus vulgaris Cuvier, 1797 in the Atlantic coast of Andalusia between May 2001 and May 2002. A total of 673 specimens of total weight ranging from 30 to 3,732 g were analysed. The gonad development was defined by means of histological methods and gonadosomatic indexes. Four gametogenic stages were identified in males (I immature, II maturing, III mature, IV spawning) and in females (I immature, II maturing, III pre-spawning, IV spawning). The sex ratio obtained was not significantly different from 1:1 (P>0.01). Mature males were found during the whole year, September being the month when the highest rate of sexually active individuals occurred (48%). In females, the gametogenic cycle commenced in December and ended in November, and spawning occurred between April and October, with two maximum peaks in August and September (48% in each). Size at sexual maturity was 850 g of total body weight for males and 1,250 g of total body weight for females. Males mature earlier than females.Communicated by S.A. Poulet, Roscoff     

Short-term effects of data-loggers on Cory’s shearwater (<Emphasis Type="Italic">Calonectris diomedea</Emphasis>)

We investigated the possible effects of a 12-g data-logger attached to a darvic ring on the performance of Corys shearwater (Calonectris diomedea, 600–850 g) from two different colonies in the western Mediterranean Sea. We compared return rates, current breeding success and body condition between equipped and unequipped birds. Effects on feeding ecology during winter and breeding period was also evaluated through the measurement of stable isotopes of carbon (¹³C) and nitrogen (¹⁵N) in one of the colonies. We found no evidence of negative effects of loggers on demographic parameters analysed or in feeding ecology. Power analyses suggested a high power to detect medium effect size, but a low power to detect small changes. Despite the non-significant results we could only exclude medium to strong effects of the devices on one of these parameters. We detected some short-term negative effects on body condition for the equipped birds, but these were unlikely to have had important consequences. Results suggest that the use of loggers is an adequate methodology to obtain information from seabirds at sea, but data should be carefully interpreted with regard to potential biases during severe environmental conditions.Communicated by S.A. Poulet, Roscoff     

Reproductive strategy of<Emphasis Type="Italic"> Calanoides carinatus</Emphasis> and<Emphasis Type="Italic"> Calanus helgolandicus</Emphasis> during a summer upwelling event off NW Spain

Reproductive activity and production of the calanoid copepods Calanus helgolandicus and Calanoides carinatus were measured during a summer upwelling event off the coast of NW Spain. The upwelling pattern affected the distribution and fecundity of both species in the study area. The demographic composition of both populations and the stage of gonad maturation (e.g. the high abundance of fertilised females with mature ova) indicated active reproduction. C. carinatus, a highly fecund species associated with the African upwelling zones and considered as an upwelling specialist, showed low production rates (overall means of 15 eggs female^–1 day^–1 and 3% body C day^–1), despite the fact that the food conditions (high phytoplankton biomass dominated by diatoms) seemed to be optimal for this species. By contrast, C. helgolandicus, a temperate species that shows a strong link between spring phytoplankton blooms and reproduction time, seems to be flexible enough to take full advantage of shorter-term, enhanced feeding conditions associated with the pulsed nature of the summer coastal upwelling. Both the egg and carbon-specific production rates attained by this species (overall means of 26 eggs female^–1 day^–1 and 12% body C day^–1) were similar to values reported for a spring bloom situation. This high production would imply a long spring–summer recruitment event of C. helgolandicus in these waters. For both species the stage of gonad maturation was significantly correlated with their egg production rates and likely influenced by the food conditions; a species-specific nutritional requirement for final oogenesis is suggested. The carbon condition factor (carbon weight/prosome volume) of C. carinatus females was higher than that of C. helgolandicus, suggesting differential use of the carbon ingested; C. helgolandicus seems to use all ingested carbon to produce eggs at a high rates, whereas C. carinatus seems to store part of the ingested carbon as lipid reserves to ensure female survival and to support production during subsequent unfavourable food conditions.Communicated by S.A. Poulet, Roscoff     

Lifting a veil on diversity: a Bayesian approach to fitting relative-abundance models.

Bayesian methods incorporate prior knowledge into a statistical analysis. This prior knowledge is usually restricted to assumptions regarding the form of probability distributions of the parameters of interest, leaving their values to be determined mainly through the data. Here we show how a Bayesian approach can be applied to the problem of drawing inference regarding species abundance distributions and comparing diversity indices between sites. The classic log series and the lognormal models of relative- abundance distribution are apparently quite different in form. The first is a sampling distribution while the other is a model of abundance of the underlying population. Bayesian methods help unite these two models in a common framework. Markov chain Monte Carlo simulation can be used to fit both distributions as small hierarchical models with shared common assumptions. Sampling error can be assumed to follow a Poisson distribution. Species not found in a sample, but suspected to be present in the region or community of interest, can be given zero abundance. This not only simplifies the process of model fitting, but also provides a convenient way of calculating confidence intervals for diversity indices. The method is especially useful when a comparison of species diversity between sites with different sample sizes is the key motivation behind the research. We illustrate the potential of the approach using data on fruit-feeding butterflies in southern Mexico. We conclude that, once all assumptions have been made transparent, a single data set may provide support for the belief that diversity is negatively affected by anthropogenic forest disturbance. Bayesian methods help to apply theory regarding the distribution of abundance in ecological communities to applied conservation.     

Preliminary patterns of distribution and abundance of loggerhead sea turtles,<Emphasis Type="Italic"> Caretta caretta</Emphasis>, around Columbretes Islands Marine Reserve,Spanish Mediterranean

Aerial surveys were conducted to estimate the abundance and distribution of loggerhead turtles (Caretta caretta) in the Columbretes Islands Marine Reserve and surrounding waters (western Mediterranean). Four surveys were carried out during 2000 and 2001, following the line transect methodology. Loggerheads appeared to be present at high densities in the area throughout the whole year, although density varied between seasons, being more abundant during the spring. Mean density in the study area was 0.322 turtles/km² (range 0.200–0.516) and the mean abundance was 1,324 turtles (range 825–2,124). The turtles were distributed homogeneously throughout the study area, we found no difference in loggerhead density between the water around the reserve and that in the rest of the study area. Current conservation measures planned by the local authorities, which include increasing the area of the reserve, would be very positive for the conservation of this stock.Communicated by S.A. Poulet, Roscoff     

The energetics and evolution of intraspecific predation (egg cannibalism) in the anchovy Engraulis capensis

Anchovy feeding activity (based on samples collected around the South African coast between 1986 and 1988) seems to peak twice daily, with the major peak between 17:00 and 19:00 hrs. Mean daily consumption in the field was estimated at 3.45% of body wt d^-1. Since the various food types available to anchovy differ in their caloric values, this figure might be expected to vary according to the type of diet available to the fish. To obtain a diet energetically equivalent to that measured in the field anchovy feeding exclusively on phytoplankton would need to consume the equivalent of 5.8% of their body wt d^-1 and those feeding on zooplankton 3.5 to 4.5% of the body wt, while fish feeding on their own eggs would require only 2.5% of their body wt daily. Feeding on eggs at peak spawning on the spawning grounds —where there is limited alternative food (i.e., zooplankton) available — seems adequate to support reproduction. In selection at the population level, cannibalistic fish benefit from homeostatic self-regulation.     

Investigating the sources of the mutagenic activity found in a river using the Salmonella assay and different water extraction procedures

In the routine São Paulo state (Brazil) surface water quality-monitoring program, which includes the Salmonella microsome mutagenicity assay as one of its parameters, a river where water is taken and treated for drinking water purposes has repeatedly shown mutagenic activity. A textile dyeing facility employing azo-type dyes was the only identifiable source of mutagenic compounds. We extracted the river and drinking water samples with XAD4 at neutral and acidic pH and with blue rayon, which selectively adsorbs polycyclic compounds. We tested the industrial effluent, raw, and treated water and sediment samples with YG1041 and YG1042 and compared the results with the TA98 and TA100 strains. The elevated mutagenicity detected with YG-strains suggested that nitroaromatics and/or aromatic amines were causing the mutagenicity detected in the samples analyzed. Positive responses for the blue rayon extracts indicated that mutagenic polycyclic compounds were present in the water samples analyzed. The mutagen or mixture of mutagens present in the effluent and water samples cause mainly frameshift mutations and are positive with and without metabolic activation. The Salmonella assay combined with different extraction procedures proved to be very useful in the identification of the origin of the pollution and in the identification of the classes of chemical compounds causing the mutagenic activity in the river analyzed.     

Decolorization of synthetic dyes using a copper complex with glucaric acid

Selected azo, acridine, triphenyl methane, anthraquinone and thiazine-based dyes were decolorized using a catalytic system consisting of Cu(II)/glucaric acid/H(2)O(2). More than 90% decolorization was obtained with 100 ppm Acridine Orange, Azure B, Chicago Sky Blue, Crystal Violet, Methyl Orange, Poly B-411, Reactive Black 5, Reactive Blue 2, and Remazol Brilliant Blue R within 24 h. Seventy to eighty percent decolorization was achieved within the first 6 h. The decolorizaton was not affected by pH. The involvement of hydroxyl radicals produced in the system in the decolorization of the dye molecules was confirmed by electron spin resonance study.     

Contribution of the gasoline distribution cycle to volatile organic compound emissions in the metropolitan area of Mexico City

Gasoline distribution in the metropolitan area of Mexico City (MAMC) represents an area of opportunity for the abatement of volatile organic compound (VOC) emissions. The gasoline distribution in this huge urban center encompasses several operations: (1) storage in bulk and distribution plants, (2) transportation to gasoline service stations, (3) unloading at service stations' underground tanks, and (4) gasoline dispensing. In this study, hydrocarbon (HC) emissions resulting from breathing losses in closed reservoirs, leakage, and spillage from the operations just listed were calculated using both field measurements and reported emission factors. The results show that the contribution of volatile HC emissions due to storage, distribution, and sales of gasoline is 6651 t/year, approximately 13 times higher than previously reported values. Tank truck transportation results in 53.9% of the gasoline emissions, and 31.5% of emissions are generated when loading the tank trucks. The high concentration of emissions in the gasoline transportation and loading operations by tank trucks has been ascribed to (1) highly frequent trips from distribution plant to gasoline stations, and vice versa, to cope with excessive gasoline sales per gasoline station; (2) low leakproofness of tank trucks; and (3) poor training of employees. In addition, the contribution to HC evaporative and exhaust emissions from the vehicles of the MAMC was also evaluated.