Gianluca Poeta

Marine litter in Mediterranean sandy littorals: Spatial distribution patterns along central Italy coastal dunes

Sandy shores are generally considered important sinks for marine litter and the presence of this litter may represent a serious threat to biotic communities and dune integrity mostly due to cleaning activities carried out through mechanical equipment. In spring (April-May) 2012 we sampled 153 2×2m random plots to assess the spatial distribution patterns of litter on Central Italy sandy shores. We analysed the relationship between the presence of litter and coastal dune habitats along the sea-inland gradient. Our results showed that the most frequent litter items were plastic and polystyrene. Differences of marine litter spatial distribution were found between upper beach and fore dune habitats and fixed dune habitats: embryo dune and mobile dune habitats show the highest frequency of litter, but, surprisingly, marine litter did not impact fixed dune habitats, these possibly acting as a natural barrier protecting the inner part of the coast from marine litter dispersion.

The cotton buds beach: Marine litter assessment along the Tyrrhenian coast of central Italy following the marine strategy framework directive criteria

We assessed the annual accumulation rates of beach litter on the Tyrrhenian coast of central Italy, providing the characterization of litter following European standardized guidelines. Three different sites of a beach were sampled seasonally from spring 2014 to winter 2015. A total of 31,739 items were removed and classified into 103 categories. Plastic represented the majority (94.4%) of the collected items. We detected temporal and spatial differences in the abundance and composition of litter between seasons and between sites. Furthermore, we found that plastic cotton bud sticks composed >30% of the total amount of litter and, together with plastic and polystyrene pieces, made up >70% of the total items. Finally, our results led us to propose that the most effective strategy to reduce litter pollution is to devise specific management procedures focusing on the most abundant items.

Plastisphere in action: evidence for an interaction between expanded polystyrene and dunal plants

Among the many threats that can be recorded on sandy beaches, plastic litter represents a serious problem for these complex and endangered ecosystems. Expanded polystyrene (EPS) is increasingly abundant as a form of plastic litter in natural environments, particularly along shores and waterways. Nevertheless, despite the great number of scientific articles concerning the impact of litter on animal species, there are still no research focusing on the interaction between this type of beach litter and other biodiversity components. In this work, we reported the first evidence of interactions between EPS and living plants along a sandy beach of Tyrrhenian central Italy. We sampled 540 EPS items, mainly deriving from fishery activities (>75%). We obtained evidence for an interaction between EPS and plants: about 5% of items resulted perforated or have roots of three species (Phragmites australis, Spartina versicolor, Anthemis maritima). Apparently, we did not observed a relationship between plants and EPS items size. More research is needed to assess if the plant assemblage growing on EPS is random or if peculiar substrate exerts some sort of selection on the plant community.

Measuring non-biological diversity using commonly used metrics: Strengths, weaknesses and caveats for their application in beach litter management

Due to increasing worldwide anthropogenic pressure and in order to promote adequate environmental conservation strategies, quantification of non-biological diversity, such as considering marine and beach litter, is becoming increasingly useful. Information on beach litter in terms of richness and diversity may have a consistent influence regarding the evaluation of its pressure and impact on coastal ecosystems. Highlighted are strengths, weaknesses and caveats concerning the use of uni- and bi-variate diversity metrics applied to a class of man-made non-biological objects periodically accumulated on the beaches. Two case studies show evidence that the application of diversity metrics on non-biological objects may have different implications. In absence of a universal and standardized non-biological taxonomy, it is important to be cautious when comparing values obtained from non-living assemblages, in particular if different sites, time or operators are considered. Moreover, different indices provide different information. Therefore, users should pay particular attention on the application of diversity metrics, addressing specific research questions and avoiding automatic calculation of redundant and “magic” indices.

An Unexpected Consequence of Plastic Litter Clean-Up on Beaches: Too Much Sand Might Be Removed

We removed plastic meso- and macro-litter (PML) during a beach clean-up practice on a protected Mediterranean sandy beach in central Italy from the high tide line to a berm half-way up the beach and from the berm to a sand dune the rest of the way up the beach. Plastic fragments, cotton buds, and expanded polystyrene (EPS) fragments were the most common categories constituting about 90% of total abundance. We separated sand from PML and found that the weight of the sand was about 14% of the total weight removed. Although our data may be affected by local factors, they have general implications for management actions. Environmental practitioners who develop projects in beach cleaning should pay attention when removing PML since a significant amount of sand could be unintentionally removed resulting in unnecessary material in landfills or other disposal, and over time potentially could significantly affect sandy beaches.

Role and Effects of Disturbances in Natural Systems

Disturbances constitute a complex set of events that play a very important role in the structure and functioning of environmental systems. They induce a change in their state and cause a large portion of the temporal variability and spatial heterogeneity that can be observed at different scales of reference and grains of definition (Whittaker 1965, 1972; Wiens 1989; Hobbs and Huenneke 1992; Myster 2003).

Nomenclature and Taxonomy of Threats

Conservation biology is an action-oriented scientific discipline. Practitioners in this field need to utilize a standard terminology which allows clarification of the concepts involved, information acquisition, and quick sharing/transfer of the experiences (Pullin and Stewart 2006).

Applying diversity metrics to plastic litter ‘communities’: a first explorative and comparative analysis

In this explorative study we applied a set of uni- and bi-variate diversity metrics (α-diversity, Whittaker β-diversity, γ-diversity, Whittaker plot) to two sampled ‘communities’ of anthropogenic beach litter. Meso-litter represented the ‘species’ with the highest number of items. Comparing the two sampled sites, we observed different values in total number of items, in α-, β- and γ-diversity and in the shape of Whittaker plot: we think that these results might have implication for assessing the impact of marine litter and the necessary operation measures aimed to its removal: (i) the higher is the amount of litter, the higher the effort in its removal, (ii) the higher is the α- and γ-diversity, the higher the number of tools and equipment to differentiate it, (iii) Shannon index, evenness and β-diversity provide interesting information on, respectively, diversity of sources, their frequency distribution and turnover, so implying different impacts on specific sensitive targets in different sites and the necessity of oriented operational actions. Moreover, the higher is the β-diversity, the higher the heterogeneity of litter with implication on a possible change of resources and equipment involved. Although we highlighted some caveat in the use and misuse of diversity metrics in beach litter management, we suggest further application of these indices to beach litter ‘communities’ to build a general conceptual framework in this sense.

The Disturbance Regime

To thoroughly understand the extent, the spatial and temporal articulation and the action modalities of a disturbance event on one or more particular environmental components present in a site, knowing its specific regime is a necessary starting point (White and Pickett 1985).

Disturbances and Coexistence of Species

Some conceptual models have been proposed to attempt an explanation of the mechanisms of coexistence of species groups inside environmental systems subjected to disturbances. Some of these models emphasize the role disturbances (and, more specifically, their regimen) may have in maintaining or altering the diversity of species observed in the ecosystems (Petraitis et al. 1989; McCabe and Gotelli 2000).