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The origin of multicellular animals and how multicellularity evolved is one of those difficult and delicate biological problems that has been pondered over for centuries. This book attempts to summarize some of the more recent results in phylogenetics and developmental biology that address the evolution of key innovations in metazoans. The book has three main sections. The first section contains five chapters that address the phylogenetic issues involving this part of the tree of life. Even though modern genome technology has made it possible to study these issues using a vast information database the elucidation of the relationships in this part of the tree of life continues to be elusive. The second section of the book addresses some of the more prominent questions concerning the developmental biology of metazoan evolution. The topics in this section focus on nervous system development, sensory organ development and developmental systems. The third section of the book focuses on the evolution of pattern and process in the incredible forms of life that we call Metazoa. The topics covered in this part of the book include the evolution of life histories, ecological associations and the evolution of biogeochmical aspects of metazoa. The book has over 40 illustrations and an up to date bibliography of over 500 references. Each chapter concludes with a set of questions for study and discussion to assist instructors and students in delving more deeply into the topics covered by the seventeen chapters in the book. Table of Contents Introduction: A Phylogenomic Journey Through the Animal Tree of Life: Key Innovations in the Evolution of Metazoa; B. Schierwater and R. DeSalle Tangled Roots in the Animal Tree of Life Putting Animals in their Place Within a Context of Eukaryotic Innovations; D. Vazquez, L. Wegener Parfrey and L.A. Katz Elucidating Animal Phylogeny: Advances in Knowledge and Forthcoming Challenges; K.M. Kocot, J.T. Cannon and K.M. Halanych Key Transitions in Animal Evolution: a Mitochondrial DNA Perspective; D.V. Lavrov Pending Issues in Development and Phylogeny of Arthropods; J.S. Deutsch The Earliest Animals: From Genes to Transitions The Pre-nervous System and Beyond—Poriferan Milestones in the Early Evolution of the Metazoan Nervous System; M. Nickel A Key Innovation in Evolution, the Emergence of Neurogenesis: Cellular and Molecular Cues from Cnidarian Nervous Systems; B. Galliot, M. Quiquand, M. Miljkovic-Licina and S. Chera From Cnidaria to "Higher Metazoa" in One Step; F. Boero and S. Piraino Basal Metazoan Sensory Evolution; D.K. Jacobs, D.A. Gold, N. Nakanishi, D. Yuan, A. Camara, S.A. Nichols and V. Hartenstein Cnidarian Gene Expression Patterns and the Origins of Bilaterality—Are Cnidarians Reading the Same Game Plan as "Higher" Animals?; E.E. Ball, D.M. de Jong, B. Schierwater, C. Shinzato, D.C. Hayward and D.J. Miller Key Transitions During Animal Phototransduction Evolution: Co-duplication as a Null Hypothesis for the Evolutionary Origins of Novel Traits; T.H. Oakley and D.C. Plachetzki Vertebrate Hox Genes and Specializations in Mammals; C. Kappen Pattern and Process at the Base of the Metazoan Tree of Life Field Biology of Placozoans (Trichoplax): Distribution, Diversity, Biotic Interactions; V. Buchsbaum Pearse and O. Voigt Trichoplax and Placozoa: One of the Crucial Keys to Understanding Metazoan Evolution; B. Schierwater et al. A Food’s-Eye View of Animal Transitions; N.W. Blackstone Lost in Transition: The Biogeochemical Context of Animal Origins; E. Gaidos Redefining Stem Cells and Assembling Germ Plasm: Key Transitions in the Evolution of the Germ Line; J. Srouji and C. Extavour Questions and Discussion

A new genus and species of hydroid, Zanclella bryozoophila, symbiotic with bryozoans is described. The colony is polymorphic and highly integrated with its bryozoan host. The gastrozooids have one or, rarely, two tentacles; dactylozooids are without tentacles. The medusa stage is reduced to liberable eumedusoids produced on the hydrorhiza, and has exumbrellar nematocyst chambers. The cnidome of both stages consists of stenoteles and macrobasic euryteles. General morphology and cnidome structure place this newly described form in the Zancleidae. A new genus is recognized on the basis of polymorphism of the hydroid and reduction of the medusa stage. The association with the bryozoan is described as commensal. Hydranths appear to feed on particles gathered by ciliary action of the bryozoan lophophore, and the hydrorhiza is surrounded by the bryozoan skeleton. The advantage of this relationship to the bryozoan is believed to be protection, effected by the nematocysts of the hydroid.

Estimating diversity of modular organisms may be problematic due to actual difficulties in discriminating between 'individuals' and quantifying their abundances. Quantitative data, when available, are collected through methods that could preclude the application of classical diversity indices, making comparisons among studies difficult. Taxonomic distinctness indices, such as the 'Average Taxonomic Distinctness' (Delta(+)) and the 'Variation in Taxonomic Distinctness' (Lambda(+)) may represent suitable tools in investigating diversity beyond the simple species number. The potential usefulness of such indices has been explored almost exclusively on unitary organisms, neglecting modular ones. In this study, we employed Delta(+) and Lambda(+) to analyse patterns of diversity of epiphytic hydroid assemblages living on Cystoseira seaweeds at a hierarchy of spatial scales, along 800 km of rocky coast (SE Italy). ANOVA on species richness and Lambda(+) showed no significant difference in sample diversity at the investigated spatial scales. In contrast, there were significant differences at the scale of 10s of km in Delta(+). Analyses based on simulations detected significant variations at all spatial scales in Delta(+). Such findings underline the potential of Delta(+) in highlighting relevant spatial scales of variation in patterns of hydroid diversity. Our results also suggest that the interplay between natural environmental variations and the complex ecological traits of modular organisms might affect taxonomic distinctness indices. We stress the need for further investigations focusing on modular organisms before any generalizations on the use of taxonomic relatedness measures in examining marine biodiversity can be made.

In spite of being one of the most relevant components of the biosphere, the plank- ton-benthos network is still poorly studied as such. This is partly due to the irregular occurrence of driving phenomena such as gelatinous plankton pulses in this realm. Gelatinous plankters rely on their life cycles and histories to exploit temporarily abundant resources with an undeniable, but often overlooked, impact on marine food webs. Dramatic increases of gelatinous filter-feeders and/or carnivores (both native and nonindigenous species) are frequently observed, and explana- tions of these blooms alternatively invoke ecosystem variability, climate change, unspecified anthropogenic perturbation or removal of top predators from trophic networks. Gelatinous plank- ters, however, are not anomalies in plankton dynamics: the recognition of the ecological impor- tance of their pulses, based on their life cycle patterns (often involving benthic stages), is a critical breakthrough to understand the cycling diversity of plankton in space and time. The current study focuses on the many neglected aspects of the ecology and biology of gelatinous zooplankton, describes how life cycle patterns are central in marine ecology, as are the pulses of gelatinous organisms, and highlights how such a dramatic lack of knowledge can affect our understanding of the marine ecosystem as a whole.

Marine protected areas (MPAs) have become popular tools worldwide for ecosystem conservation and fishery management. Fish assemblages can benefit from protection provided by MPAs, especially those that include fully no-take reserves. Fish response to protection can thus be used to evaluate the effectiveness of marine reserves. Most target fish are high-level predators and their overfishing may affect entire communities through trophic cascades. In the Mediterranean rocky sublittoral, marine reserves may allow fish predators of sea urchins to recover and thus whole communities to be restored from coralline barrens to macroalgae. Such direct and indirect reserve effects, however, are likely to be related to the enforcement implemented. In Italy, many MPAs that include no-take reserves have been declared, but little effort has been spent to enforce them. This is a worldwide phenomenon (although more common in some regions than others) that may cause MPAs and reserves to fail to meet their targets. We found that 3 of 15 Italian marine reserves investigated had adequate enforcement, and that patterns of recovery of target fish were related to enforcement. No responses were detected when all reserves were analyzed as a whole, suggesting enforcement as an important factor to be considered in future studies particularly to avoid that positive ecological responses in properly managed reserves can be masked by neutral/negative results in paper parks. Positive responses were observed for large piscivores (e.g. dusky groupers) and sea urchin predators at reserves where enforcement was effective. Those reserves with low or null enforcement did not differ from fished areas.

Luminous bacteria are isolated from both Hydrozoa and Bryozoa with chitinous structures on their surfaces. All the specimens of the examined hydroid species (Aglaophenia kirchenpaueri, Aglaophenia octodonta, Aglaophenia tubiformis, Halopteris diaphana, Plumularia setacea, Ventromma halecioides), observed under blue light excitation, showed a clear fluorescence on the external side of the perisarc (chitinous exoskeleton) around hydrocladia. In the bryozoan Myriapora truncata, luminous bacteria are present on the chitinous opercula. All the isolated luminous bacteria were identified on the basis of both phenotypic and genotypic analysis. The isolates from A. tubiformis and H. diaphana were unambiguously assigned to the species Vibrio fischeri. In contrast, the isolates from the other hydroids, phenotypically assigned to the species Vibrio harveyi, were then split into two distinct species by phylogenetic analysis of 16S rRNA gene sequences and DNA-DNA hybridization experiments. Scanning electron microscopy analysis and results of culture-based and culture-independent approaches enabled us to establish that luminous vibrios represent major constituents of the bacterial community inhabiting the A. octodonta surface suggesting that the interactions between luminous bacteria and the examined hydrozoan and bryozoan species are highly specific. These interactions might have epidemiological as well as ecological implications because of the opportunistic pathogenicity of luminous Vibrio species for marine organisms and the wide-distribution of the hydrozoan and bryozoan functioning as carriers.

The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database. For each species, the following information is reported: description, cnidome, biology, occurrence in Salento, worldwide distribution, and bibliography. Descriptions refer to the benthic hydroid stage and, when present, also to the planktonic medusa stage. The 115 species of Hydrozoa, recorded along the Salento coastline, represent 25% of the Mediterranean Hydrozoa fauna (totaling 461 species), and nearly 3% of 3,702 world's known species covered in a recent monograph. Four species are non-indigenous, three of them with invasive behavior (Clytia hummelincki, Clytia linearis, and Eudendrium carneum), and one species now very common (Eudendrium merulum) in Salento. The complete life cycle of Clytia paulensis (Vanhoffen, 1910) is described for the first time.

1. Understanding whether Marine Protected Areas (MPAs) can be considered as a suitable tool for restoring the structure and function of populations and assemblages is urgently needed to achieve an effective policy of mitigation of human impact in coastal management. However, to date, the role played by MPAs in enhancing ecosystems resilience has been more advocated than unambiguously documented. 2. This study was designed to test whether full protection in marine reserves facilitates recovery of benthos impacted by the date mussel Lithophaga lithophaga fishery, one of the most harmful human activities affecting subtidal rocky habitats in the Mediterranean Sea. 3. The effects of this destructive fishery were reproduced at one fully protected location (P) and at two unprotected control locations (Cs) in the SW Mediterranean Sea. At each location, three plots (4 m2) of rocky surface at 4-6 m depth were disturbed experimentally, while another three plots served as reference. In each plot, the species composition and relative cover of the sessile benthic assemblages were sampled photographically on each of five occasions during a period of 20 months. 4. Over and above variation in habitat features among locations, multivariate and univariate analyses revealed significant differences between P-vs.-Cs in patterns of assemblage recovery and showed that, at the fully protected location, recovery was faster than at the unprotected control locations. 5. Our results suggest that MPAs have the potential to change the trajectories of recovery of disturbed assemblages by accelerating the processes of recolonization and call for further investigation to identify the specific mechanisms underlying increased resilience.

A previously unknown association between a luminous bacterium, Vibrio harveyi, and a benthic hydrozoan, Aglaophenia octodonta, is described. Aglaophenia hydrocladia showed a clear fluorescence in the folds along the hydrocaulus and at the base of the hydrotheca, suggesting the presence of luminous bacteria. This hypothesis was confirmed by isolation of luminous bacteria from Aglaophenia homogenates. Phenotypic characterization of bacterial isolates was performed by several morphological, biochemical, and cultural tests, completed with 16S rDNA sequence analysis. All the isolates were referred to a single species: V. harveyi. The association between V. harveyi and A. octodonta has epidemiological as well as ecological significance. Therefore, A. octodonta may function as habitat "islands" providing a unique set of environmental conditions for luminous bacteria colonization, quite different from those already recorded from the plankton for other Vibrio species.

Many hydroids are symbiotic with other organisms. Sponges, because of their complex canal system and their filter-feeding activity inducing a continuous water flow, are used by numerous species as either exclusive or facultative substrata. The associated hydroid fauna thriving on or inside sponges shows a wide range of relationships with their hosts. Hydroids may be simply epibiotic on sponges, their stolons running on the host surface. Alternatively, the stolons may grow inside the sponge body, the polyps emerging from the sponge surface, having also the possibility of retraction inside the sponge tissue. Finally, stolons and branches may develop deeply inside the sponge body, producing a skeletal network for sponge growth. This paper reviews the described relationships of hydrozoans symbiotic with sponges and reports new observations.

The recent setting of specific features of the Cnidaria into evolutionary and ecological frameworks suggests the centrality of this phylum in many fields of the life sciences. From an evolutionary point of view, the Cnidaria, with their diploblastic planulae, might represent the ancestral state of higher Metazoa in the light of a peramorphic origin of animal complexity from a simple, individual organism. Medusan development in the Hydroidomedusae via a medusaty nodule, furthermore, implies the formation of a third tissue layer (the muscle layer lining the subumbrellar cavity). Cnidarian polyps are diploblastic, whereas at least some of their medusae are triploblastic: the evolutionary enigma of the passage from a diplo- to a triploblastic organisation takes place every time hydrozoan polyps bud medusae! Cnidarian polyps have also the premises of the skeletal architecture of higher animals: their chitinous or carbonatic skeletons are similar to those of arthropods and vertebrates respectively. From an ecological point of view, the coelenterates probably play roles that are much more important than usually perceived. Both Cnidaria and Crenophora feed on the eggs and larvae of most benthic, planktonic and nektonic organisms and might be crucial (with a keystone role?) in maintaining biodiversity high, by feeding on potentially monopolising species. The efficiency of gelatinous predators becomes evident during periodic Outbreaks of their populations, with serious implications even on fisheries yields, demonstrating that their impact can be higher than ours!.

Macroalgal beds in temperate rocky habitats provide shelter and food for many adult reef fishes and their juvenile stages. In the Mediterranean Sea, the fishery of the endolithic date-mussel Lithophaga lithophaga (which involves dismantling of rocky substrates inhabited by these bivalves) may cause formation of barrens in shallow rocky reefs. Preliminary data collected in SW Apulia (SE Italy) show that rocky reefs impacted by this destructive fishery display different distribution patterns of adult Coris julis (a common labrid fish in the Mediterranean basin), and lower abundance of juveniles. The ecological implications of date-mussel fishery for dynamics of fish populations and rocky-reef ecosystem functioning (e.g., nursery role) are discussed.

Marine protected areas (MPAs) are aimed at managing and protecting marine environments. Their design, however, often disregards both a thorough knowledge of the distribution of habitats and assemblages and the use of proper experimental evaluations of the efficacy of MPAs by comparing protected vs. unprotected zones. About 200 MPAs have been recently instituted in the Mediterranean area, but the evidence of their efficacy is scant. The MPA of Torre Guaceto (Southern Adriatic Sea, Italy) is one of the rare cases of effective protection enforcement. The reserve was instituted more than 10 years ago, a period currently considered as sufficient to show responses by organisms to protection. The MPA is divided into a C zone, the general reserve, where many activities are permitted, a B zone, the partial reserve where restrictions increase and two A zones, the integral reserve where access is prohibited. The goals of the paper were to map the distribution of benthic assemblages to assess if they were properly represented in the differently protected zones, and to test the efficacy of protection by quantifying possible differences between the assemblages in two control areas and in the two A zones, where human impact is completely excluded. The analysis of habitat and assemblage distribution within the MPA showed that the zones with total protection do not include most valuable environmental types. Most of the considered variables (i.e. cover of substratum, number of taxa, and average abundance of the most common taxa) were not significantly different in and out of the A zones, at each time of sampling. Results, however, suggested a possible effect of protection in modifying patterns of abundance of sponges under Cystoseira canopy (more abundant in the fully protected zone). In the subtidal habitat, differences were found in the structure of the whole assemblage and in the abundance of encrusting coralline red algae (more abundant outside the fully protected area). Notwithstanding the correct general methodology employed in the study, a lack of statistical power could have a role in preventing the detection of ecologically relevant effects of protection. In some instances, data pooling allowed a discrimination between cases where there was clearly no effect of protection and cases where there might be. On this basis, the optimization of this experimental design should be considered in further studies. In any case, if the goals of MPAs have not been clearly stated, efficacy of protection might prove very difficult to test even with the use of sound experimental designs.

Man-made defence structures (e.g., breakwaters, jetties) are becoming common features of marine coastal landscapes all around the world. The ecology of assemblages of species associated with such artificial structures is, however, poorly known. In this study, we evaluated the density and size of fish predators of echinoids (i.e., Diplodus sargus, Diplodus vulgaris, Sparus aurata), and the density of sea urchins (i.e., Paracentrotus lividus) at defence structures (i.e., breakwaters) inside and outside the marine protected area of Miramare (northern Adriatic Sea) in order to: (1) assess possible differences in fish predator density and size between protected and fished breakwaters; (2) assess whether fish predation may have the potential to affect sea urchin density in artificial rocky habitats. Surveys were carried out at four random times over a period of two years. Total density, and density of medium- and large-sized individuals of the three predatory fishes were generally greater at the protected than at the fished breakwaters, whereas no differences were detected in the density of small-sized individuals. Density of the sea urchin P. lividus did not show any difference between protected and fished breakwaters. The results of this study suggest that: (1) protection may significantly affect predatory fishes in artificial rocky habitats; (2) differences in predatory fish density, and size may be unrelated with the density of the sea urchin P. lividus; (3) protected artificial structures such as breakwaters, originally planned for other purposes, could represent a potential tool for fish population recovery and enhancement of local fisheries.

The effects of the sea urchin Paracentrotus lividus (Lamarck) fishery, and possible indirect influences on the co-occurring (but not harvested) sea urchin Arbacia lixula (L.), were investigated in shallow rocky reefs in southern Apulia (SE Italy, Mediterranean Sea). Density, size (test diameter), biomass and size-frequencies of both species were assessed in summer 2001 at one location heavily impacted by P. lividus fishery (recreational and commercial), and at three controls. Average sea urchin density (pooling P. lividus and A. lixula), and density of P. lividus did not significantly differ between the impacted location and the controls, while average density of A. lixula was significantly greater at the location where P. lividus was fished. The average size of P. lividus was significantly lower at the exploited location than at the controls, whereas that of A. lixula did not differ. Total sea urchin biomass (pooling P. lividus and A. lixula) did not differ between the exploited location and the controls. The average biomasses of P. lividus and of A. lixula, conversely, were lower and greater, respectively, at the fished location than at the control sites. In some cases, distribution patterns of the investigated variables (i.e., density, size and biomass) were affected by fishery at the spatial scale of a few metres (i.e., between replicates). At the controls, P. lividus larger than 4 cm (the threshold size for commercialisation) accounted for about one third of the populations surveyed, whereas at the fished location specimens of this size were rare. Size-frequency distributions of A. lixula were fairly similar at the fished and control locations. Although appropriate experimentation would be needed to confirm these patterns, the present study provides suggestive evidence that intense P. lividus harvesting may cause reduction in average size and biomass of this echinoid because of the selective harvesting of largest specimens. Densities of P. lividus at fished and control areas, instead, did not change, which suggests that P. lividus populations subject to fishing could have the potential to recover by appropriate management policies (e.g., catch quotas). Indirect effects of the P. lividus harvesting on the co-occurring A. lixula suggest a possible competitive dominance by P. lividus in the absence of selective fishing on this latter species, and a sort of compensation when it is fished. Implications for management of P. lividus exploitation, and for possible ecological consequences of the sea urchin fishery, are also discussed.

We surveyed shallow, rocky reefs in southwestern Apulia (Mediterranean Sea) to assess the effects on coastal fish assemblages of the date mussel ( Lithophaga lithophaga) fishery, an illegal practice that strips the rocky reef bare. We visually sampled fish four times over 15 months at three locations, one affected by date-mussel fishery and two controls. The fish assemblage at the affected location differed significantly from those at the control locations over all sampling times. Herbivorous fishes, sparids, and labrids (genus Symphodus) contributed most to the differences between the affected location and controls. Lower densities of Symphodus spp. were observed at the affected location, whereas detritivorous fishes were recorded exclusively at control sites. Small serranids and sparids showed temporal trends that differed between the affected location and the control locations. Our results suggest that the date-mussel fishery affects fish assemblages chiefly through reduction of arborescent macroalgae (contributing to habitat complexity and primary production) and emphasize the need for more effective policing against this destructive practice. Resumen: Muestreamos arrecifes rocosos someros en Apulia sudoccidental (Mar Mediterraneo) para evaluar los efectos de la pesqueria de Lithophaga lithophaga, una practica ilegal que desnuda al arrecife rocoso, sobre ensambles de peces costeros. Visualmente muestreamos peces cuatro veces a lo largo de 15 meses en tres localidades diferentes, una afectada por la pesqueria y dos controles. El ensamble de peces en la localidad afectada difirio significativamente de los sitios control en todos lo tiempos de muestreo. Los peces que mas contribuyeron a las diferencias entre la localidad afectada y los controles fueron herbivoros, esparidos y labridos (genero Symphodus). En la localidad afectada se observaron densidades menores de Symphodus spp., mientras que en los sitios control se registraron peces detritivoros exclusivamente. Serranidos pequenos y esparidos mostraron tendencias temporales que difirieron entre la localidad afectada y los controles. Nuestros resultados sugieren que la pesqueria de mejillon afecta principalmente a los ensambles de peces por la reduccion de microalgas arborescentes (que contribuyen a la complejidad del habitat y a la produccion primaria) y enfatizan la necesidad de politicas mas efectivas contra esta practica destructiva.

The microplankton community was studied at 9 sites (29 sampling stations) along the Salento Peninsula (SE Italy). Integrated samplings from both the water column (to collect active stages), and sediments (to collect resting stages), were carried out. More than 400 taxa were recognised in total. As for phytoplankton, 64 taxa were new records from the area. In particular, 16 of them were found only as resting stages in the sediments. A harbour, a coastal lake, and a submerged cave were investigated to understand the role of confined or sheltered environments in the accumulation of resting stages. The harbour and the lake were found to be biodiversity reservoirs, due to the abundance of resting stages in their sediments. Only few species were found both in the water column, as plankton, and in the sediments, as resting stages. Furthermore, the most abundant species in the water column were not equally dominant as resting stages in the sediments. This suggests that species other than those observed in the plankton during the present work (i.e., those found as dominant among resting stages in the sediments) dominated the plankton in the past. Furthermore, they could dominate the future plankton, with multiannual cycles, starting from sediment reservoirs. The search for resting stages in the sediment, thus, is useful to discover temporarily rare species, because species persist in the sediments as resting stages for longer periods than those spent as active stages in the plankton. Se estudió la comunidad microplanctónica en 9 localidades (29 estaciones de muestreo) a lo largo de la península de Salento (Italia sudoriental). Se realizaron muestreos integrados de la columna de agua (para recolectar estados activos) y de los sedimentos (para recolectar estados quiescentes). En total, se reconocieron más de 400 táxones. En lo que respecta al fitoplancton, 64 táxones fueron nuevas citas para la zona. En particular, 16 de ellos se encontraron únicamente como estados quiescentes en el sedimento. Se estudiaron un puerto, un lago costero y una cueva submarina para comprender el papel de los ambientes confinados o resguardados en la acumulación de estados de quiescencia. Se encontró que el puerto y el lago eran depósitos de biodiversidad, debido a la abundancia de estados quiescentes en sus sedimentos. Sólo unas pocas especies se encontraron a la vez en la columna de agua, como plancton, y en los sedimentos, como estados quiescentes. Además, las especies más abundantes en la columna de agua no eran igualmente dominantes como estados quiescentes en los sedimentos. Esto sugiere que el plancton del pasado estaba dominado por otras especies (es decir, las que son más abundantes entre los estados quiescentes en el sedimento), distintas de las que se han observado en el plancton durante el presente trabajo. Además, dichas especies podrían dominar el plancton futuro, con ciclos multianuales, iniciados a partir de los depósitos de los sedimentos. Así, pues, la búsqueda de estados quiescentes en el sedimento es útil para descubrir especies que son raras a la escala temporal, porque las especies persisten como estados de quiescencia durante períodos más largos que los que pasan como estados activos en el plancton.

The hydrozoa life cycle is characterized, in normal conditions, by the alternation of a post-larval benthic polyp and an adult pelagic medusa; however, some species of Hydrozoa react to environmental stress by reverting their life cycle: i.e. an adult medusa goes back to the juvenile stage of polyp. This very uncommon life cycle could be considered as some sort of inverted metamorphosis. A morphological study of different stages during the reverted life cycle of Turritopsis nutricula led to the characterization of four different stages: healthy medusa, unhealthy medusa, four-leaf clover and cyst. The ultrastructural study of the cellular modifications (during the life cycle reversion of T. nutricula) showed the presence of both degenerative and apoptotic processes. Degeneration was prevalent during the unhealthy medusa and four-leaf clover stages, while the apoptotic rate was higher during the healthy medusa and cyst stages. The significant presence of degenerative and apoptotic processes could be related to the occurrence of a sort of metamorphosis when an adult medusa transforms itself into a polyp.

Taxonomic sufficiency (TS) involves the identification of taxa only to a level of taxonomic resolution sufficient to permit the detection of changes in stressed assemblages. Recently, however, TS has been proposed also for conservation issues as a tool to estimate biodiversity over large areas and in poorly known environments. This paper briefly reviews the use of TS in environmental impact studies and the effects of TS on sampling procedures and data analyses. The risk of possible loss of information depending on TS and the studied environment are discussed. Concluding remarks deal with the dangers of loss of taxonomic expertise in marine biological studies and assess critically the proposal of TS as a tool to describe biodiversity at a taxonomic level higher than species. (C) 2003 Elsevier Science Ltd. All rights reserved.

Biogeographia vol. XXIV - 2008 (Printed October, 3 1 st 2003) Marine biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity Who cares about the Hydrozoa of the Mediterranean Sea? An essay on the zoogeography of inconspicuous groups FERDINANDO BOERO*, JEAN BOUILLON**, CINZIA GRAVlLl*, STEFAN O PlRAlNO* *Dz'ptzrz‘i77zem‘0 di StiE7'2Z€ e Teena/ogie Biologic/7e eA77zbz’e72z‘t1/2', Strzzione 511' Bio/ogizz Mzzrimz e Museo dell 14172/7z'e72te, Univerxitfz di Lecce, ./373100 Lecce (Italy). **.l'.zzbonztoz're de Biologie Ma7qiI2e, C/Vziversite /ibre de Bruxelles, 50 A2/. FD. Roosevelt, 1 05 0 Bruxelles (Belgium) Key words: I-Iydrozoa, Mediterranean Sea, zoogeography. SUMMARY The Messininan crisis, 5 MY before pi'esent, marked the recent history of the Mediterranean Sea. The opening of Gibraltar, and the inflow of Atlantic water, brought in the ancestors of the species that inhabit the Mediterranean today. The opening of the Suez Canal allowed the entrance of Indo-Pacific species. Ships and aquaculture transported species from all over the world. At present, the Mediterranean Sea is a melting pot ofa blend of biota that probably has no equivalent in any other part of the world. The tropicalisation of the Mediterranean and Lessepsian migration are conductive to the establishment of tropical species into the basin, with some outstanding examples like that of Cm;/eipzz species, and of the scyphomedusa R/Japilenm mnmzdirzz. At present, the arrival of new conspicuous species is well monitored and researchers are ready to publish new records of recognisable species. These usually belong to popular groups such as fish, molluscs and decapod crustaceans, or to groups that cannot pass unnoticed due to a marked attitude to form outbreaks, like dinoflagellates or scyphozoan jellyfish and ctenophores. \Vhat about the other groups? The bulk of biodiversity, in terms of species numbers, is made of poorly known and inconspicuous species that, usually, can be noticed only by specialised taxonomists. Taxonomy is disappearing from most scientific communities, so that our appreciation of biodiversity is being biased towards conspicuous groups, The Hydrozoa are taken as an example of inconspicuous group whose knowledge has greatly progressed in the last decades due to the presence of some specialists in the Mediterranean area. The number ofspecies recorded from the Mediterranean almost doubled in thirty years and the number of new records is still increasing‘ The ecological rble of these animals, especially those represented also by a medusa stage, can be great due to their general ability to Feed upon fish eggs and larvae and/or on the plankton that fish larvae feed upon, so acting as potential predators and/ or competitors of commercial species. They might even be keystone predators, depressing potentially monopolising fish species, so leaving space for less competitive species. Neglecting this component of biodiversity might lead to ecological misunderstandings that, in their turn, might lead to misleading interpretations of the causes afTecting the yield offisheries. The main question arising from the example of the Hydtozoa is: are conspicuous groups sufficient to appreciate marine biodiversity and understand its functioning? The answer deriving from the example of the Hydrozoa is: No!

Shallow rocky habitats in SW Apulia (SE Italy, Mediterranean Sea) were surveyed in late spring 2002 to assess distribution patterns of sea urchins (Paracentrotus lividus and Arbacia lixula) and barren habitats (coralline barrens and bare substrates) in rocky reefs impacted by the destructive fishery of the rock-boring date-mussel Lithophaga lithophaga. Sea urchin density, test size-structure and biomass, and the percent cover of barrens were evaluated at four locations (5-6 km apart from each other), two heavily impacted by the date-mussel fishery and two controls. Sea urchin density and barren habitat cover were assessed at two and three sites (100-300 m apart), respectively, within each location. Sea urchin biomass was evaluated only at the scale of locations. Average density of P. lividus did not significantly change between impacted locations and controls, whereas A. lixula showed a greater density at the impacted locations. Distribution patterns of A. lixula, in addition, differed at the spatial scale of a few metres between impacted locations and controls, being generally more aggregated at the controls. The size-frequency distribution (test diameter) of P. lividus showed a mode at 3-4 cm at the impacted locations compared to a mode at 2-3 cm in the controls. The size-frequency of A. lixula was bimodal at the damaged locations (with modes at 1-2 and 4-5 cm, respectively) and unimodal (with the mode at 4-5 cm) at the controls. Average biomass of both sea urchins (P. lividus and A. lixula) was two- to fourfold greater at the impacted locations (similar to600 g wet wt m(-2)) than at the controls (150-250 g wet wt m(-2)). Barren habitats had a far greater average cover (mainly of macroalgae) at the impacted locations (from 79% to 96%) than at control locations (from 7% to 21%). These results show that the date-mussel fishery may have the potential to affect distribution patterns of sea urchins and to greatly enhance the percent cover of barren grounds in shallow Mediterranean rocky reefs.

An oceanographic survey was carried out along the Salento Peninsula in March 2000. Resting stages of plankton were searched for in coastal sediments to study the microplankton composition in addition to the classical analysis of active stages in the water column. A total of 215 taxa were recognised, 149 as active stages in the water column and 74 as resting stages in the sediments. Cysts were widely distributed and at Brindisi and Alimini their abundance was higher than elsewhere. A general trend was observed with resting stage abundance, species richness and diversity in the sediments: all three decreased with distance from the coast. The integrated water/sediments approach used in this study allowed us to collect 37 species (mainly as resting stages) new for the studied area.

The structure and organisation of aquatic communities, moulded in each environment by combinations of abiotic factors, recruitment and productivity rates, rely upon a network of both pairwise and transitive interactions among organisms. In many cases, a few strong interactors drive basic ecological processes by playing a leading role in channelling the available resources. Among these, keystone species may control the outputs of local biodiversity through large indirect effects, disproportionately large relative to their abundance. Functional roles are not fixed labels, and species interactions have variable outputs in both time and space: also, in spite of a growing literature on species interactions, terminology is often poorly applied. This leads to the loss of the informative value of concepts, like the keystone species, which might represent useful trade-offs between science and environmental politics. Species’ roles are often used to set taxonomic conservation priorities, although this might even be regarded as unethical, ecologically wrong, or in disregard of the evolutionary meaning of species coexistence and interaction. A re-assessment of species’ roles is given here, attempting to highlight their limits and applicability. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00227-001-0769-2.

Coastal fish assemblages were studied to assess two sorts of human impacts in southwestern Apulia (SE Italy, Mediterranean Sea). Fish assemblages were evaluated by visual census along two rocky locations impacted by a sewage outfall discharging nearshore (S) and by date-mussel (Lithophaga lithophaga) fisheries (F), respectively, and at two control locations (Cs). Multivariate analyses showed that fish assemblage structures at S and F differed from those at Cs. Asymmetric ANOVAs indicated that species richness were significantly lower both at S (approximately 27%) and at F (approximately 35%) compared with Cs. Total fish abundance was 5- to 7-fold higher at S than at Cs, while the values recorded at F were comparable to those of Cs. At S, average abundances of planktivorous fish and POM feeders were higher, and those of labrids and sparids of the genus Diplodus were lower, respectively, than at Cs. Labrids of the genus Symphodus and small serranids were significantly less abundant at F than Cs. Data suggested that coastal fish respond to the impact caused by the sewage discharge and provided a framework to assess potential benefits of its future displacement to deeper waters. For the first time, moreover, this study provided suggestive evidence that the habitat destruction caused by the illegal date-mussel fisheries may affect fish assemblages.

Science is often carried out with two apparently different approaches. Some scientists make experiments, whereas others make observations; the first ones manipulate the objects they scrutinize, whe...

A bloom of an unknown semaestome jellyfish species was recorded in the North Adriatic Sea from September 2013 to early 2014. Morphological analysis of several specimens showed distinct differences from other known semaestome species in the Mediterranean Sea and unquestionably identified them as belonging to a new pelagiid species within genus Pelagia. The new species is morphologically distinct from P. noctiluca, currently the only recognized valid species in the genus, and from other doubtful Pelagia species recorded from other areas of the world. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal DNA genes corroborate its specific distinction from P. noctiluca and other pelagiid taxa, supporting the monophyly of Pelagiidae. Thus, we describe Pelagia benovici sp. nov. Piraino, Aglieri, Scorrano & Boero.

Zoology and anthropology are usually considered as distinct disciplines, with different scientific communities, journals, scientific societies. The Italian Zoological Union (UZI) and its journal, t...

1. Marine fouling affects most man-made surfaces temporarily or permanently immersed in the sea, resulting in significant (or substantial) economic costs. Intense research is aimed at preventing or reducing fouling. 2. The most widespread solution to avoid fouling formation is to make surfaces unsuitable for settlers, coating them with antifouling (AF) paints containing toxic compounds. Most AF agents (e.g. tributyltin, (TBT)) have undesirable effects on non-target species, including commercially important organisms. 3. To date, the use of TBT in AF paints has been restricted (but not prohibited) in a number of countries and new biocides are in use. 4. The environmental problems posed to marine systems by AF technologies are here briefly reviewed. 5. New approaches focusing on alternatives to the use of biocidal AF paints are also considered and discussed. Copyright © 2001 John Wiley & Sons, Ltd.

The recognition of the value of biological diversity, especially after the famous Rio convention, has caused a flurry of national and international plans aimed at the exploration of biodiversity. Biodiversity is a magic word that opens many doors in funding agencies 1xAn international biodiversity observation year. Wall, D et al. Trends Ecol. Evol. 2001; 16: 52–54Abstract | Full Text | Full Text PDF | PubMed | Scopus (8)See all References1. The three definitions of biodiversity (subspecific, specific and supraspecific) involve genetic, organism, population and ecological approaches, even though the concern about biodiversity stems from the still unanswered question ‘How many species are there on earth?’ 2xHow many species are there on Earth?. May, R.M. Science. 1988; 241: 1441–1449Crossref | PubMedSee all References2.Genetics at a molecular level and ecology at a functional level were well represented in the scientific arena even before the biodiversity frenzy, whereas the science of species description, naming and classification (taxonomy and systematics) is passing through a world crisis that is far from being solved. There are two reasons for this crisis. One is the non-existent Impact Factor (IF) of most of the journals that publish species descriptions and taxonomic revisions. The IF is a widely used parameter to score the performance of researchers, leading to career opportunities and advancements. If you have a low IF, your future is dark. The other reason is that species description is seen as an old-fashioned way of doing research. The result is that experts in taxonomy retire and are not replaced, zoology and botany disappear from university curricula and new researchers in biodiversity end up being either molecular biologists or ecologists.Too extreme a statement? Consider this: a recent paper on animal evolution in Trends in Genetics 3xAnimal evolution, the end of intermediate taxa?. Adoutte, A et al. Trends Genet. 1999; 15: 104–108Abstract | Full Text | Full Text PDF | PubMed | Scopus (137)See all References3 included a glossary explaining the following terms: Bilaterians, Cambrian explosion, Clade or Natural group, Diploblasts, Evolutionary radiation, Metazoans, Monophyletic taxon, Phylum, Superphylum, Synapomorphy, Taxon, Triploblasts. This means that the editor of this journal supposes that a general reader interested in animal evolution is not familiar with these concepts. Look at a species list in a standard ecological paper and check how accurate are the data sets that, often, are then analyzed with the most sophisticated statistical packages.This is the dark. And here is the light. The dismissal of taxonomy worldwide originated from the USA. This mistake has now been recognized and a strategy has been implemented in the USA to correct it. The National Science Foundation of the USA has realized that taxonomy is dying and that the USA cannot have a scientific community that is deprived of taxonomists. This led to the launch of the Partnership for Enhancing Expertise in Taxonomy (PEET) (http://web.nhm.ukans.edu/∼peet/). Although other countries have begun to neglect their taxonomic expertise, they still have taxonomists and the situation is not as dire as that in the USA. Italy, for example, is the only country to have published a complete checklist of its fauna simply because it still has a breed of taxonomists 4xSystematics and biodiversity. Minelli, A. Trends Ecol. Evol. 1994; 9: 227Abstract | Full Text PDF | PubMed | Scopus (4)See all References4. Italian taxonomists are, however, getting older and are not being replaced, meaning that Italy is suffering today from the same mistake that affected the USA scientific community some 20 years ago. These non-USA countries harbor the experts in traditional taxonomy (those in the USA are very advanced in molecular aspects) and often provide the actual founders of the new breed of USA taxonomists. The PEET project on the Hydrozoa, for instance, is based on work by an Italian and a Brazilian student.A PEET taxonomist is a blend of a traditional morphological specialist and a molecular systematist. These two approaches to biodiversity rarely interact, producing paradox that traditional taxonomists have many problems that their techniques cannot solve, whereas molecular taxonomists have powerful techniques but not so many problems to solve, once the most obvious ones have been done. A standard product of a PEET project is a thorough revision of a taxon, which includes studying all the existing literature, inspecting type specimens, collecting new material, molecular analysis of specimens referred to as many nominal taxa as possible, disentangling of synonymies and production of a phylogeny based on both morphological and molecular approaches.Despite having no impact, taxonomic publications have eternal life and one cannot ignore old descriptions simply because they are old. A complete library is thus a prerequisite for good taxonomic work. Many PEET projects require that bibliographic data bases are made available through the Internet for free, also with the option of downloading articles in PDF format when possible. In this way, taxonomy will be enhanced not only in the USA but also in the rest of the world. As an example, refer to the bibliographic database on the Hydrozoa (http://siba2.unile.it/ctle/hydro/index.php3).The prominence of Europe as a land of taxonomists will not last long unless more PEET-like projects are launched soon, each with a carefully planned strategy of specialist training and proper career opportunities. If this does not happen, in 20 years, Europeans will send their youngsters to learn taxonomy in the USA.The problem of the decline of taxonomy, finally, is also due to taxonomists. Specialists in astrophysics are able to convince funding agencies to invest enormous amounts of money to look for extraterrestrial life. The same people who invest public money in these irrelevant enterprises 5xThe probability of extraterrestrial intelligent life. Mayr, E. : 67–74See all References5 are obviously not convinced by taxonomists that it is worthwhile investing money to explore the life of this planet!

The ecological importance of resting stages in shallow waters is well known, but their presence in the deep sea is practically unrecorded. Samples of sinking particles were collected from April 1993 to May 1994 in and around the Foix Canyon (northwest Mediterranean Sea) using PPS3 sediment traps located between —600 m and —1180 m. Dead and viable organisms were collected, and inorganic empty shells constituted most of the biologically-derived matter. Resting stages, considered as POM, had a flux of up to 70 000 items m−2 d−1. They were the second most abundant fraction of total POM after tintinnids (mainly represented by empty, chitinous loricas), and first of the viable POM fraction. Most remained unidentified, but 58 morphotypes were referable to coastal species of Dinophyta, Tintinnina and Calanoida. Resting stages were rare in samples collected from the open slope adjacent to the canyon. These preliminary data suggest an important role of submarine canyons in concentrating POM and transferring it from shallow to deep-sea habitats. Due to their resistance to degradation processes, resting stages are probably the only POM component that can return to shallow areas by upwelling currents occurring in the canyon.

The non-native estuarine shrimp, Palaemon longirostris H. Milne Edwards, 1837, is reported for the first time on the Sinop Peninsula coast (southern Black Sea). The species is previously known to occur in the northeastern Atlantic Ocean and the eastern Mediterranean including the Aegean Sea and the Sea of Marmara. © 2007 The Author(s). Journal compilation.

In temperate seas, many plankters avoid unfavourable periods by producing resting stages which accumulate in the sediments to form biodiversity banks from which plankton communities are seasonally restored. Most resting stages have typical spiny coverings. This morphology is common across phyla, and even kingdoms, and favours flotation, passive transport, and sensory activity, also opposing both predation and burial into the sediments. Spiny coverings are considered a convergence allowing survival of resting forms.

Plankton and benthos are popular concepts identifying two ways of life of aquatic organisms. Their spatial separation led to the development of different sampling techniques and to separate conceptualizations of the principles governing these subsets of the aquatic environment. Reciprocal connections between plankton and benthos, however, are very strong both from a functional (energy fluxes) and a structural (life cycle dynamics) point of view. A full appreciation of such links is forcing marine ecology towards a more integrated approach.

An integrated sampling of both active (cells in water column) and resting stages (cysts sinking to the bottom) of phytoplankton, was carried out on March 1996 in the Mar Piccolo of Taranto. At least 46 taxa were recognized in the water column. Cyst sinking rate was about 23,000 m-2 d-1. Out of 37 recognized morphotypes, mainly dinoflagellates, 18 were previously unrecorded from the area. The present sampling represents the preliminar test to outline an experimental design to an integrated study of plankton dynamics.

Proofs that climate change is a reality are increasingly evident: undeniably, the abiotic factors of today have changed much in respect to just a few decades ago. The bearing of these changes, howe...

The manifold aspects of variability of coastal marine ecosystems are reviewed, with special reference to the response of species and communities. Fluctuations are defined as recurrent modifications in community structure, for instance due to seasonality, whereas variations are defined as changes permanently leading from a given community to a different one. Both patterns are described and linked to the interaction between life history traits and environmental factors. Resting stages are proposed to play a still underestimated role in the dynamics of coastal communities, especially for plankton. Rare species are considered as an essential constant of communities, being the source of potential variation and alternance in the contribution to the standing biomass.

The Mediterranean parrotfish Sparisoma cretense is reported for the first time along the south-eastern coasts of Apulia (Ionian Sea, south-east Italy). Only juvenile specimens of S. cretense were observed during visual census surveys carried out in late August 2000, whereas adults were never observed in, or reported from, this region. Juvenile parrotfish were 3–4-cm long (TL), with a light-grey livery, pale-yellow heads and marked yellow margins around the eyes. They were recorded at 5–15 m depth, whereas they were absent near the surface (0–2 m depth) and in deeper areas (25–28 m depth). The possibility that climatic changes occurring in the Mediterranean basin (i.e. water warming) would be involved in the spreading of S. cretense outside its typical distribution range is discussed.