Giuseppe Cognetti

Biodiversity and adaptive mechanisms in brackish water fauna

A comparative analysis of estuaries, lagoons and coastal ponds focusing on population differentiation, and community structure is necessary to correctly address the issue of brackish water biology. Although the different biotopes all present similar features of environmental unpredictability and the common presence of the hypohalobic contingent (artenminimum), they each have their own characteristics, due to the evolution of peculiar balances in their relation to the sea on the one hand and inland waters on the other. In addition to euryhaline species, locally adapted populations of stenohaline species typical of marine habitats, as well as some recently introduced species, are also found. These species have given rise to euryhaline populations, reaching their maximum development in an optimal site. This situation occurs between basins with essentially similar ecological features and probably depends both on the different degree of adaptability of many species to a specific environmental parameter and the type of biocoenoses adjacent to the brackish basin. These populations possess genotypes allowing adaptation to brackish waters, which have resulted in the differentiation, through selection, of individuals capable of fine-grained perception of environmental unpredictability. Experimental works demonstrated the existence of genetically differentiated populations, or, ultimately, sibling species complexes, in several brackish species with broad geographical distribution and belonging to a wide range of taxonomic groups. The conceptions regarding the uniformity of brackish elements and the doubts concerning the existence of a specific brackish fauna come from the fact that attention generally focuses on species in the traditional meaning of the term, that is to say at the macrosystematic level. Comparative analyses of very fine morpho-physiological changes and genetic analyses result in a rather different picture, leading to the conclusion that in brackish waters a given species of marine origin often consists of many different forms at various levels of differentiation.

Colonization of stressed coastal environments

Stressed environments are dominated by a few species capable of adaptation to extreme variations of environmental parameters and to the presence of certain toxic substances. These species called opportunistic (McArthur, 1960), offer different degrees of adaptability to respond to unpredictable events. The comparative study of marine stressed environments is of great interest to assess the analogy of adaptation and colonization mechanisms for different species.

Perspectives on the ecological assessment of transitional waters

Brackish water biotopes (lagoons, estuaries, salt marshes, and coastal ponds) constitute transitional waters systems, the main characteristic of which is the instability of chemical and physical parameters and characteristic bio-ecological aspects (Cognetti, 1994; Cognetti and Maltagliati, 2000; Bilton et al., 2002). European transitional waters include a large range of diversified ecosystems of very important scientific and economic value; very often they are threatened by the effect of multiple anthropogenic activities. Their conservation needs careful attention and specific actions based on appropriate biological and ecological knowledge. Furthermore, a concept that differentiates the conservation approach of many transitional environments, such as coastal lagoons and coastal ponds, from the other aquatic biotopes is their ‘‘anthropodependence”. In fact, natural ecological succession of lagoon ecosystems proceeds toward a number of changes to the final transformation into terrestrial ecosystems. The maintenance and conservation of lagoon environments requires, and has required since ancient times, periodic human intervention, especially as regards lagoon aquaculture. The levels of uncertainty about the mechanisms and processes occurring in transitional waters makes it difficult to translate the assessment and the conservation strategies into political recommendations because they greatly differ from general guidelines that are effective for other ecosystems. For instance, if we consider the problem of water eutrophication, it is often difficult to disentangle the contribution of pressure by human activities from natural causes. Hence, appropriate and specific methodologies are required for the assessment of the ecological status of transitional environments. These methodologies may greatly differ from those classically used in marine or freshwater ecosystem monitoring, as recommended by the EU Water Framework Directive (WFD, 2000/ 60/EC). In fact, the concept of ecological quality status (EQS), included in the WFD as a way to assess the ecological quality of aquatic environments, can be sometimes unsuitable when applied to transitional waters (Dauvin, 2007). Additionally, another difficulty depends on biogeogeographical differences of various European basins. Currently, many attempts are being made to adapt biotic indices to specific situations related to transitional waters within a restricted geographical region. For instance, Munari and Mistri (2007) proved the effectiveness of a biotic index that did not conform to the WFD in four Tyrrhenian lagoons. Nevertheless, the importance of WFD has been underlined by Borja (2005), who depicted WFD as an opportunity to develop, standardise and implement a unique European methodology for monitoring and assessment of the status of aquatic ecosystems. This point was discussed in an international congress within the American Society of

Ecosystem service provision: An operational way for marine biodiversity conservation and management

Since no extensive conceptual framework has been developed on the issues of ecosystem service (ES) and service provider (SP) in the marine environment, we have made an attempt to apply these to the conservation and management of marine biodiversity. Within this context, an accurate individuation of SPs, namely the biological component of a given ecosystem that supports human activities is fundamental. SPs are the agents responsible for making the ES-based approach operational. The application of these concepts to the marine environment should be based on an model different to the terrestrial one. In the latter, the basic model envisages a matrix of a human-altered landscape with fragments of original biodiversity; conversely, in the marine environment the model provides fragments where human activities are carried out and the matrix is represented by the original biodiversity. We have identified three main classes of ES provision: in natural, disturbed and human-controlled environments. Economic valuation of marine ESs is an essential condition for making conservation strategies financially sustainable, as it may stimulate the perceived need for investing in protection and exploitation of marine resources.

Adaptive strategy of brackish-water fauna in pure and polluted waters

Abstract A comparative analysis of various brackish-water biotopes has indicated certain characteristics of the community structure, and the colonization and adaptation of various species to very different ecological situations. A large diversity of the fauna in the various biotopes has been ascertained, each of them showing peculiar properties. Together with species typical of these environments, there are many others, often until now never collected in brackish waters, which, according to different local situations, characterize and distinguish various situations. A comparison of the fauna between brackish waters and sea waters polluted by organic wastes point out to what degree adaptive strategies are analogous. Genetic variability of the organisms makes standardization of monitoring methods difficult in these unpredictable environments.

La partenogenesi negli Afidi

Abstract A comparative study of the parthienogenetic and amphigonic egg development of Aphids, has shown & clear resemblance between some aspects of the two maturative processes. In the amphigonie egg bivalents become indistinet soon after the stage of highest contraction. In the parthenogenetie egg however the bivalents the stae of highest contraction. In the parthenogenetie egg however the bivalents separate and the diploid number of chromosomes is restored within the nuelear membrane. The second maturative division originates, in the partheogenetic egg a single diploid polar body. In the amphigoni egg the emission of two aploid polar bodies occurs in the normal way. In both ovogenetic processes the bivalents reach threfore the highest contraction stage before the «resting» stage. A delay in the beginning of the resting stage of the nucleus is shown therefore in the egg maturation of Aphids, which is not shown in most other Inscets orders. Such peeculiar behaiour of the chromosomes of the amphigonic egg...

On some aspects of the ecology of the benthic littoral Polychaetes

Abstract Many studies carried out in environments polluted mainly by organic matter, point out the gradual change from biologically adapted communities to communities predominantly physically controlled where only a few well-represented species survive. However, of these factors the one concerning the nature of the bottom loses more and more of its importance in the distribution of Polychaetes and no longer has that fundamental importance which is ascribed to it as a limiting factor in biologically accomodated communities. This is an extreme example of the adaptive strategy of species with respect to the difficulties of the environment. In areas subject to mainly organic pollution, the extreme consequence of which is the disappearance of O2 from the water, saprobic species adapt with different degrees of resistence (opportunistic species). However, it does not seem very convincing to draw a sharp distinction between opportunistic and non-opportunistic species, and a distinction between the degrees of oppo...

Ecology of Polychaetes in the Orbetello lagoon (Tuscany)

Abstract In Orbetello lagoon 68 polychaete species have been collected. Their distribution related to different environmental conditions agrees with the Sanders stability-time hypothesis. However, the physically controlled communities of the most eutrophicated areas are not influenced by the type of bottom. Therefore the distribution becomes uniform and the nature of the bottom is no longer a limiting factor as for biologically accommodated communities in the lagoon zones more influenced by the sea. The opportunism of several species is discussed.

Autofecondazione in Asterina.

Summary In Asterina, the sperm appears when the eggs come out from the oviducte; moreover it is able to fertilize all the spawned eggs. It is assumed that in A. pancerii this spermatogenetic stage has a true functional meaning; indeed the young spermatogenetic stage is missing together with the partenogenetic development. In free individuals of A. pancerii probably there is not self-fecundation, at least for most of the eggs; the spawning in isolated bred animals of the species occurs indeed at the same hour in groups of individuals. In A. gibbosa the adaptive meaning of the secondary spermatogenesis is probably to be considered as the possibility for isolated individuals to occupy new areas.

Antifouling coatings and ecological control in marinas

The progressive increase of boat tourism and the consequent development of marina activities gives rise to a series of problems related to safeguarding the natural environment. Therefore, there is a need for appropriate monitoring of port facilities and water quality, as well as the development of new technologies dealing with yachting activities, suitable to minimizing their impact on biological communities. The peculiar ecological characteristics of marinas for their mono-functionality allow the accurate assessment of the different effects of specific contaminants on marine organisms. In fact, marinas constitute a valuable observation point from which pollution can be assessed on the basis of the responses of natural populations and communities, and make easier the control of the various pollutants, such as waste fuels, sewage discharges from craft and municipal waters and release of biocide from antifouling coatings. In particular, these paints are one of the main causes of concern and require careful assessment, in order to avoid deleterious effects on the natural environment. Biocide-based antifouling paints are a significant localized source of trace elements (in particular copper and zinc) and organic biocide in the water. In industrial ports the effects of antifouling paints on the biological component can be hardly distinguished from other sources of biocides, such as those generated by industrial activities, commercial shipping and agriculture. Therefore, taking advantage of marinas’ peculiarities in order to assess the effects of the different antifouling paints on marine organisms is an intriguing task. The need to use antifouling coatings is due to the occurrence of fouling organisms, such as algae, barnacles, and tube worms, which recruit and grow on any submerged surface, greatly increasing drag and reducing speed and fuel economy of boats. In the last decades, many biocides, such as tributyltin (TBT) copperand zinc-based compounds, were introduced in order to restrict the recruitment and growth of fouling organisms on ship and boat hulls. TBT has been referred to as perhaps the most effective antifouling biocide. Nevertheless, due to its negative effects on nontarget organisms, it was banned from 2001 onwards, according to the decisions taken by the International Convention on the Control of Harmful Antifouling Systems on Ships, adopted by the International Maritime Organization (IMO). Subsequently, the removal of over-coating of TBT antifouling paints became mandatory from 2008 (IMO, 2001). However, due to the high level of effectiveness of TBT paints, the risk of illegal use is present, even though it should be of minor concern in marinas with respect to commercial and industrial ports. Copper in the form of cuprous oxide continues to be a mainstay antifouling biocide but not necessarily the most effective. It re-