The future of the Mediterranean Sea Ecosystem: towards a different tomorrow

The structure and function of the Mediterranean Sea Ecosystems (MSE) are rapidly changing. Global warming is the main driver of change, and the MSE responses are dramatic. The establishment of non-indigenous species, heavily influenced ecosystem functioning; human pressures such as overfishing, triggered regime shifts such as that from fish to jellyfish; the Eastern Mediterranean Transient changed the circulation patterns of the Eastern Mediterranean basin. Models did not predict these changes. Science, so far, focused much on the constraints that lead to regular sequences of events, allowing for predictions. In periods of rapid change, though, the historical nature of ecology becomes prominent, and contingencies acquire an overwhelming importance. This calls for new approaches to the study of complex systems, for instance with a shift from monitoring to observation, with a revival of natural history. The identification of cells of ecosystem functioning, based on oceanographic processes that enhance production at different levels of marine food webs in specific areas, is a challenge for future studies that will eventually lead to better management and protection of the marine natural heritage. Even if historical systems do not allow for predictions, some trends are clear and a set of possible scenarios of what will happen in the future Mediterranean Sea can be proposed

La nostra specie, le leggi della natura e le priorità scientifiche

La nostra specie è un prodotto dell'evoluzione biologica e vive all'interno di sistemi ecologici (ecosistemi) da cui trae beni e servizi. La natura viva obbedisce a leggi che vanno oltre quelle che regolano la natura non viva. La legge della crescita impone a tutte le specie uno sforzo riproduttivo che ha come risultato l'aumento numerico degli individui che le rappresentano. La legge del limite impedisce che la crescita di qualunque specie possa andare oltre la capacità portante: il numero massimo di individui che un dato ecosistema può sostenere. Tutte le specie obbediscono attivamente alla prima legge (la crescita) e sono sottoposte passivamente alla seconda (il limite) che viene imposta dal sistema di sostegno e non dalla specie che, se potesse, continuerebbe a crescere all'infinito. La nostra specie, pur essendo in grado di capire anche la legge del limite, continua a perseguire la crescita infinita e sta erodendo le proprio possibilità di continuare ad avere un ruolo nel gioco della natura. Oggi, la priorità per la nostra sopravvivenza è di comprendere la struttura e la funzione degli ecosistemi e prendere atto della legge del limite, in modo da riparare agli errori del passato. Il primo sintomo di questi errori è il cambiamento climatico. Gli scienziati che studiano la natura vivente ripetono da decenni che ci stiamo comportando in modo poco avveduto, ma altri scienziati non accettano gli allarmi e ne negano il valore, entrando in campi in cui non sono competenti. Undicimila scienziati che lavorano in campi ambientali avvertono l'umanità che abbiamo sei priorità non più eludibili: 1 - cambiare il modo di produrre energia, in modo da uscire finalmente dall'età del fuoco, 2 - smettere di introdurre inquinanti nell'ambiente, 3 - rispettare la natura, comprenderne la struttura e la funzione e darle la possibilità di rigenerarsi, 4 - produrre cibo in modo sostenibile, 5 - concepire un'economia che non miri solo alla crescita del capitale economico, senza considerare la conseguente erosione del capitale naturale, 6 - fermare la bomba demografica: il pianeta non può sostenere un numero infinito di umani e, quindi, ci dobbiamo fermare. Se non lo faremo noi volontariamente lo farà la natura, imponendo la legge del limite. Non esistono priorità più impellenti, ne va della nostra possibilità di sopravvivere come specie intelligente

Changes and Crises in the Mediterranean Sea: Current problems

As a contribution to the World Environment Day 2017, the Accademia Nazionale dei Lincei promoted the meeting “Changes and Crises in the Mediterranean Sea” devoted to the effects of climate change and human impact on the Mediterranean ecosystems and biodiversity. Here is presented a selection of papers given at the meeting held in Rome, on October 17, 2017. Studies deal with structural changes in the marine communities, the impact of thermal stress, acidification, pollution and fishing activities on benthic communities, and on deep-sea biodiversity and ecosystems. Understanding human impact on the Mediterranean Sea is the first step to manage and protect marine environments in a sustainable way

The historical reconstruction of distribution of the genus Halecium (Hydrozoa: Haleciidae): a biological signal of ocean warming?

The distribution of 130 nominal species of the genus Halecium, based on published records, has been mapped for the first time in a comprehensive set of marine ecoregions, to analyse their distribution. Most Halecium species are found at mid- and high latitudes, with some overlaps in distribution ranges across regions. The species richness of Halecium is strongly related to the latitudinal gradient, with maximal diversity at polar and temperate latitudes. Previous detailed studies in the Mediterranean Sea show that large Halecium species of coldwater affinity have regressed or disappeared in recent years, probably due to global warming. Worldwide, however, the overall species richness of Halecium has not changed along the latitudinal gradient over recent decades, with some changes in species composition at temperate-tropical latitudes in both hemispheres, even though the majority of the species that have not been recorded for more than 50 years are of coldwater affinity. The genus can be considered an indicator for biological responses to climate changes for the Mediterranean Sea, but the available distribution data do not allow extending this possibility to the rest of the world. A focused evaluation on the distribution of Halecium species with the addition of new field data might reinforce the picture stemming from the present analysis

Marine Sciences: from natural history to ecology and back, on Darwin's shoulders

The naturalist Charles Darwin founded modern ecology, considering in a single conceptual framework the manifold aspects regarding the organization of life at various levels of complexity and its relationship with the physical world. The development of powerful analytical tools led to abandon Darwin's natural history and to transform naturalists, as Darwin labelled himself, into the practitioners of more focused disciplines, aimed at tackling specific problems that considered the various aspects of the organization of life in great detail but, also, in isolation from each other. Among the various disciplines that stemmed from the Darwinian method, ecology was further split into many branches, and marine ecology was no exception. The compartmentalization of the marine realm into several sub-domains (e.g., plankton, benthos, nekton) led to neglect of the connections linking the various parts that were separated for the ease of analyses that, in this way, prevented synthetic visions. The way marine sciences were studied also led to separate visions depending on the employed tools, so that ship-based biological oceanography developed almost separately from marine station-based marine biology. The necessity of putting together such concepts as biodiversity and ecosystem functioning is rapidly leading to synthetic approaches that re-discover the historical nature of ecology, leading to the dawn of a new natural history

Variability of species’ roles in marine communities: change of paradigms for conservation priorities.

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