Marina Antonia Colangelo

Meiofauna of the Adriatic Sea: present knowledge and future perspectives

Owing to technical problems and difficult taxonomic identification, meiofauna have been generally less studied than macrofauna. However, the role of meiofauna in marine ecosystem functioning, and their effective and rapid response to anthropogenic alterations and climatic changes have recently been acknowledged, leading to increasing scientific and applied interest. At present, systematic and biogeographic knowledge of the meiofauna of the Adriatic Sea is extremely heterogeneous, because most of the data are limited to a few taxa and the sampled areas are scattered, being located mainly in the coastal areas of the northern basin. Analysis of the composition and distribution of meiobenthic groups in the Adriatic Sea highlights the presence of several endemisms. Meiofauna also include bioindicator taxa, which allow assessment of the quality of marine sediments; this is particularly useful in systems characterised by the synergistic effect of different forms of anthropogenic impact, such as the Adriatic basin. Current knowledge about the ecology of the meiofauna and use of this component in applied ecological studies, along with the availability of a standardised protocol for the analysis of meiofaunal assemblages, allows us to recommend formal acknowledgement of the need to integrate information derived from the analysis of macrofauna with information derived from the study of meiofauna. Future research based on the simultaneous use of both of these benthic components will allow faster and more accurate evaluation of the response of coastal marine ecosystems to anthropogenic disturbance.

Comparing efficacy of different taxonomic resolutions and surrogates in detecting changes in soft bottom assemblages due to coastal defence structures

Sandy shores on the West coast of the North Adriatic Sea are extensively protected by different types of defence structures to prevent coastal erosion. Coastal defence schemes modify the hydrodynamic regime, the sediment structure and composition thus affecting the benthic assemblages. This study examines the effectiveness in detecting changes in soft bottom assemblages caused by coastal defence structures by using different levels of taxonomic resolution, polychaetes and/or bivalves as surrogates and different data transformations. A synoptic analyses of three datasets of subtidal benthic macrofauna used in studies aimed at assessing the impact of breakwaters along the North Adriatic coast has been done. Analyses of similarities and correlations between distance matrices were done using matrices with different levels of taxonomic resolution, and with polychaetes or bivalves data alone. Lentidium mediterraneum was the most abundant species in all datasets. Its abundance was not consistently related to the presence of defence structures. Moreover, distribution patterns of L. mediterraneum were masking the structure of the whole macrofaunal assemblages. Removal of L. mediterraneum from the datasets allowed the detection of changes in benthic assemblages due to coastal defences. Analyses on different levels of taxonomic resolution showed that the level of family maintained sufficient information to detect the impacts of coastal defence structures on benthic assemblages. Moreover, the outcomes depended on the transformation used. Patterns of distribution of bivalves, used as surrogates, showed low correlations with the patterns of the total macrofaunal species assemblages. Patterns of polychaetes, if identified to the species or genus level showed higher correlations with the whole dataset. However, the identification of polychaetes to species and genus level is as costly as the identification of all macrobenthic taxa at family level. This study provided additional evidences that taxonomic sufficiency is a useful tool in environmental monitoring, also in investigations on the impacts of coastal defence structures on subtidal macrofauna. The use of coarser taxonomic level, being time-efficient, would allow improving sampling designs of monitoring programs by increasing replication in space and time and by allowing long term monitoring studies.

Effects of an artificial protection structure on the sandy shore macrofaunal community: the special case of Lido di Dante (Northern Adriatic Sea)

This study analysed the benthic compartment at Lido di Dante (Northern Adriatic Sea, Italy) within the frame of an integrated European project (DELOS), which aimed to identify, describe and quantify the effects of the Low Crested Structures (LCS) on the beach environment of many European coastlines. Both macrofaunal benthic communities and sediment characteristics were analysed in a sandy beach protected by a LCS parallel to the shoreline and laterally connected to land by two groynes, which have been responsible for changes of hydrodynamic patterns. A first survey (2001) focused on three exposure levels with respect to wave action. A higher species richness and a different community structure were found in the sheltered site as compared to the exposed and partially exposed sites. In addition, changes in sediment variables were found according to the exposure levels. A second survey (2002) assessed the combined effects of exposure and depth on both benthic communities and sediment variables. Our results suggest that both exposure and depth interact on measured biotic and abiotic variables. Species richness, community structure and size-classes distribution of the macrofauna, as well as the sediment composition, showed the greatest differences among the shallowest exposed zone and the deepest sheltered ones. On the contrary no difference at all occurred between the shallowest sheltered zone and the deepest exposed ones.

Trade-off between conservation and exploitation of the transitional water ecosystems of the northern Adriatic Sea

Transitional waters (TWs) provide ecosystem goods and services that are essential for the well-being of human populations. These unpredictable aquatic systems, characterised by large environmental fluctuations, are under severe stress due to human activities. Increasing pressures (e.g. over-harvesting, eutrophication, habitat loss) inevitably lead to the degradation of these ecosystems. Analysis of the complexity of species distribution patterns within and among TW habitats is relevant to understanding the underlying processes and promoting appropriate management strategies. Assessment of the trophic status is one of the most critical aspects of TWs. Untangling the relevance of anthropogenic nutrient inputs from internal biogeochemical processes is of primary importance in defining appropriate restoration strategies. Biotic indices have been suggested as an operational tool to assess environmental quality in TWs. However, the application in TWs of indices developed for coastal waters can give distorted results (e.g. low species diversity and high abundance are natural features). The BITS approach provides a rapid assessment of ecological quality, although its sensitivity in reflecting field conditions remains to be assessed. The major challenge to TWs management is to couple long-term conservation with productive activities. This goal can be achieved using an integrated approach, forecasting conservation of TW ecosystem functioning together with sustainable economic development. North-western Adriatic TW habitats have been exploited for centuries and major shifts in ecological processes have occurred. In this study, knowledge of the ecological features of these habitats is summarised and analysed using recent ecological tools. Based on these findings, possible strategies for conservative management have been discussed.

Ecological approaches to coastal risk mitigation

Natural coastal habitats play an important role in protecting coastal areas from sea water flooding caused by storm surge events. Many of these habitats, however, have been lost completely or degraded, reducing their ability to function as a natural flood defense. Once degraded, natural habitats can potently be destroyed by storm events, further threatening these systems. Much of the loss of coastal habitats is caused by increased human activity in coastal areas and through land claimed for urban, industrial, or agricultural use. As a result, some coastal habitats have become rare and threatened across much of Europe and the world. An associated problem is that of sea level rise, which has the combined impact of both increasing the risk of flooding in coastal ecosystems and increasing the severity of storm surge events. This chapter addresses two key topics: (1) the use of natural habitats as a form of coastal defense focusing on the required management and how to restore and/or create them and (2) ecological considerations in the design of hard coastal defense structures. The habitats that play a role in coastal deface and considered here are: (1) saltmarshes, (2) sand dunes, (3) seagrass meadows, and (4) biogenic reefs, including Sabellaria reefs, oyster beds, and mussel beds. As part of coastal habitat restoration and management, the process of saltmarsh creation, either through seaward extension or managed realignment is discussed focusing on potential benefits. Finally, key cumulative stressors that can hinder ecological approaches to coastal risk mitigation are reviewed.

CHAPTER 14 – Background knowledge and tools for prediction of ecological impacts

The species pool in a particular locality is determined by its biogeographic context. The evolution of the species pool is a dynamic and ongoing process. Biodiversity patterns on a broad-scale are the functions of adaptation, extinction, and speciation. The species pool may also change following the introduction of alien species, often through human activities. Broad-scale biodiversity patterns are influenced by major physical factors, such as climate, currents, upwelling, tidal elevation, wave climate, salinity, coastal topography, and seabed composition, which can all vary with geographical location. The environmental impact of any amount of cases can be predicted by numerical modeling. The result for each case is a set of BioMar class values for physical parameters being designated for each cell. A procedure is then applied that selects the biotopes that can occur within the predicted set of parameter class values for each cell. Biotopes recorded in the field during baseline data survey can be compared with those predicted by the model. This enables calibration of the model to the present situation and allows evaluation of the type and magnitude of changes for each computed case in a straightforward fashion. These initial trials with the model are encouraging, and the model is still being refined to develop a tool to more accurately predict change in the identity and extent of biotopes because of the addition of breakwaters.