César Megina

Quantification of the age-pigment lipofuscin in brains of known-age, pond-reared prawns Penaeus japonicus (Crustacea, decapoda).

A quantitative study of the lipofuscin content was carried out by image analysis in brains of known-age, pond-reared Penaeus japonicus (Crustacea, Decapoda) with the aim of assessing the applicability of the lipofuscin technique as an estimator of the physiological age in penaeids. With this purpose, three distinct measurements of lipofuscin levels (% area fraction, granule density and mean granule size) were recorded in ten sections of the olfactory lobe cell mass (OLCM) per animal. The image analysis was based on the autofluorescence emitted by the pigment, which accentuates the contrast between the lipofuscin granules and the background tissue. The concentration of lipofuscin increased significantly with age and was independent of sex. The relationship between age and lipofuscin concentration (area fraction and granule density) was best described by a seasonalized von Bertalanffy function, since the accumulation rate of the pigment dramatically slowed down in fall-winter, probably as a result of reduced seasonal metabolism. The present results confirm the potential of the lipofuscin method in the estimation of physiological age in penaeids and suggest that the application of this methodology can be useful in studies of age structure in wild populations and in the assessment of natural resources. J. Exp. Zool. 286:120-130, 2000.

Energy and Macronutrient Assimilation Efficiencies of Snowy Plover (Charadrius Alexandrinus) Feeding on the Polychaete Ragworm Nereis Diversicolor

Abstract Macronutrient (protein, lipids, and carbohydrates) assimilation efficiencies of wild birds have rarely been studied, but they may be particularly important for estimating the optimal diet. We assessed experimentally the energy and macronutrient assimilation efficiencies of captive Snowy Plover (Charadrius alexandrinus) feeding on the polychaete ragworm Nereis diversicolor, a major natural prey for migratory shorebirds (Charadrii) along intertidal habitats worldwide. Overall, Snowy Plover consumed 8.64 ± 1.54 (SD) g of dry ragworms per day, and the apparent metabolizable energy was 136.59 ± 27.69 kJ·day−1 (3.5–4.0 times the basal metabolic rate). Assimilation efficiencies were 80.04 ± 2.04%, 93.48 ± 1.08%, 84.75 ± 2.01%, and 89.23 ± 2.61% for energy, proteins, lipids, and carbohydrates, respectively. Macronutrient assimilation efficiencies were similar during early winter and premigration and between male and female Snowy Plover. Relatively high protein assimilation by Snowy Plover may be associated with their specialized high-protein diet.

BENFES, a new biotic index for assessing ecological status of soft-bottom communities. Towards a lower taxonomic complexity, greater reliability and less effort

The new biotic index BENFES (Benthic Families Ecological Status Index) for assessing the ecological status of soft-bottom communities based on presence/absence at the taxonomic family level, is described. BENFES was primarily developed for the communities from the Guadalquivir estuary (South-western Spain), but the aim of the present work was to evaluate the reliability and validity of this index for its application in the Water Framework Directive (WFD), especially as a preliminary and rapid assessment method for monitoring the ecological status of transitional and coastal waters. BENFES was compared with five widely used indices (BOPA, BO2A, BENTIX; AMBI and M-AMBI) in several studies from Southwestern Spain. In addition, we have also established comparisons between these indices and the most commonly used Shannon-Wiener diversity. M-AMBI and BENFES showed the best agreement in ecological status assignation and were the most useful and discriminant between the studied areas. BENTIX was a good discriminant in coastal areas but was severe with the environmental condition from estuaries; BOPA/BO2A did not show clear trends in most of the zones; and AMBI tended to provide overestimations of the ecological status. In conclusion, BENFES shows several advantages such as lower taxonomic resolution, greater reliability and only requiring presence/absence. All this implies a huge possibility to perform a simplified monitoring routine for the control of the ecological quality of water bodies.

Application of cnidae composition in phylogenetic analyses of North Atlantic and Mediterranean dendrophylliid corals (Anthozoa : Scleractinia)

Abstract. Scleractinian corals are widely distributed in all oceans and at all bathymetric levels. Corals are among the most important bio-building organisms in marine ecosystems. The systematics of this hexacoral group is currently undergoing much change owing to studies that combine molecular analyses with morphological research on the calcareous skeletons. However, information from polyp anatomy has been widely ignored, and some aspects, such as the diversity and distribution of the cnidocysts, might help to obtain a better understanding of the relationships at different taxonomic levels. In this study, the cnidocysts of four species of the family Dendrophylliidae (Dendrophyllia ramea, D. cornigera, D. laboreli and Astroides calycularis) are analysed to evaluate the application of cnidae in phylogenetic analyses, and to complete our knowledge of cnidae composition (types, distribution and sizes) for these species. A discriminant analysis based on the cnidae of these species supports the usefulness of these structures. The obtained results indicate that additional morphological characters in scleractinian corals that may help to clarify their phylogenetic relationships can still be found.

Benthic assemblages, biodiversity and invasiveness in marinas and commercial harbours: an investigation using a bioindicator group.

Abstract Fouling communities on artificial marine structures are generally different from benthic communities in natural rocky habitats. However, they may also differ among different types of artificial structures. Two artificial structures in direct contact with arriving vessels were compared: floating pontoons within recreational marinas, and sea-walls within commercial harbours. Natural rocky habitats were used as a reference, and the genus Eudendrium (Cnidaria, Hydrozoa) was chosen as a bioindicator. The assemblages were different among the three types of habitat studied, with different species characterising each habitat. The probability of finding an invasive Eudendrium species was significantly higher on pontoons. Diversity was the lowest on pontoons, but it was not significantly different between sea-walls and natural rocks. In general, a barrier to the spread of exotic species exists between harbours and natural rocky habitats. Floating pontoons seem to be a less suitable habitat for native fauna and a key element in marine biological invasions.

GROWTH DYNAMICS OF ULVA ROTUNDATA (CHLOROPHYTA) IN A FISH FARM: IMPLICATIONS FOR BIOMITIGATION AT A LARGE SCALE1

Changes in biomass of several macroalgae [Ulva rotundata Bliding; Gracilariopsis longissima (S. G. Gmel.) Steentoft, L. M. Irvine et Farnham; Ulva intestinalis L.; and Cladophora sp.] and marine plants (Zostera noltii and Ruppia cirrhosa) growing naturally in earthen ponds of a fish farm (Acuinova, San Fernando, Southern Spain) were recorded during a year. The farm is mainly devoted to the culture of gilthered seabream (Sparus aurata). The most conspicuous algal species thriving in the ponds was U. rotundata, which reached densities up to 600 g dry mass · m−2 and produced up to 20.45 g C · m−2 · d−1. Dissolved nutrients (phosphate and ammonium), tissue nutrient content, and growth rates of this species were estimated during 2001 and 2002. Evidence of natural biomitigation by U. rotundata when water circulates throughout the fish farm is presented. Due to the fish cultivation, both phosphate and ammonium increased as water circulated from the preculture ponds to the postculture ponds. As a consequence, U. rotundata tissue nitrogen (N) and phosphorus (P) increased from algae growing in preculture ponds to algae growing in the outflow channel, so that mean C:N:P ratio varied from 773:57:1 in preculture ponds to 567:64:1 in the outflow channel. Phosphorus limited growth of U. rotundata during the spring. As growth rates increased as a function of tissue P, data were fitted to the Droop equation. From this equation, the estimated maximal growth rate was 0.295 ± 0.041 d−1, the subsistence quota was 0.05 ± 0.01% P of dry mass, and the critical quota was 0.215% P of dry mass. The results suggest that management of the fish farm based on a large‐scale integrated mariculture system of fish and macroalgae may increase the total ecological and economic benefits, both for the farm and for the environment.

Cnidarian Alien Species in Expansion

The study of the diversity and composition of marine communities is the first step in understanding the development of marine ecosystems. While some cnidarian populations are in decline, others invade new regions and habitats. The pressure of the human actions on the marine ecosystems has increased in the past decades. The artificial structures in marine environments, shipping, aquaculture, global warming and interoceanic canals have contributed to the dispersion, establishment and invasion of many places by alien species around the world, in some cases, with major ecological and socio-economic impacts. Some cnidarian species may serve as examples of the truly widespread reach of invasive species. Benthic phase of hydroids and anthozoans are common components of harbours and fouling communities and, probably, they have been transported on ship hulls. Ephyrae and hydromedusae are also frequently found in ballast water. Additionally, the global climatic change allows cnidarian of tropical affinity to extend their range into the temperate zones. The biological invasions and range extensions may cause local native biodiversity and economic losses. Only recently have these biological invasions attracted the attention of the scientific community. Though invasive alien cnidarians are recognized now as a global threat to biodiversity, and monitoring their presence and impacts is considered a prerequisite for marine environmental management and sustainable development, it seldom takes place even in the coastal regions most vulnerable to introductions

The northern distributional limits of Dendrophyllia laboreli (Cnidaria: Scleractinia: Dendrophylliidae)

New findings of the scleractinian coral Dendrophyllia laboreli in various localities off the European coast in the Gulf of Cadiz and the Strait of Gibraltar, as well as the Atlantic coast of Morocco, are reported. These new findings redefine the current northernmost known limit of distribution of this species, previously known in African localities from Ghana to the Canary Islands. Some ecological and biogeographical remarks are also included.

Impact of dredged-material disposal on soft-bottom communities in a recurrent marine dumping area near to Guadalquivir estuary, Spain

This study assesses the effects of dredged material disposal in a recurrent marine dump near the Guadalquivir Estuary (south-western Spain). We compared the changes observed with two reference areas combining a classical ecological approach with new stable isotope techniques to analyse trophic structure. We detected permanent changes in the macrofaunal community structure as well as in the diversity and biotic indices applied, which showed higher values in the disposal area. The community in the marine dump had lost the natural temporal variations observed in the reference areas. These effects could be due to the last disposal event carried out in the summer of 2015 or to the recurrent disposals since 2010. Despite the structural changes shown by the benthic community, these impacts were not reflected in the food web structure of the marine dump. Our results confirm the high variability of disposal disturbances. Hence, we recommend performing studies in every disposal event, merging different functional and structural approaches.

A new species of Trapania Pruvot-Fol, 1931 from the Bay of Cadiz. With remarks on other Trapania species

Abstract Trapanici sanctipetrensis n. sp. is described from the southwestern Iberian Peninsula. The ground colour is translucent white with conspicuous, irregularly spread, black or dark brown flecks. The flecks can form dark patches on the head, dorsum, flanks and tail, and are also present on the rhinophores, the gills, the lateral process, the base of the oral tentacles and the foot corners. The radula is biseriate, and has radular teeth with a wide but relatively short outer denticle. The remaining denticles are much smaller. The labial cuticle has two areas composed of elongate rodlets. A buccal pump is placed dorsally on the buccal mass. The reproductive system has the typical arrangement of the genus. The ampulla is pyriform and elongate. The bursa copulatrix is rounded and the seminal receptacle is also elongate, but smaller than the bursa copulatrix. A comparison between T. sanctipetrensis and the other Atlantic and Mediterranean species of Trapania, as well as new data on uncommon Atlantic species, are presented.