The ever-increasing level of marine pollution due to plastic debris is a globally recognized threat that needs effective actions of control and mitigation. Using marine organisms as bioindicators of ...plastic pollution can provide crucial information that would better integrate the spatial and temporal presence of plastic debris in the sea. Given their long and frequent migrations, numerous marine species that ingest plastics can provide information on the presence of plastic debris but only on large spatial and temporal scales, thus making it difficult to identify quantitative correlations of ingested plastics within well-defined spatio-temporal patterns. Given the complex dynamics of plastics in the sea, the biomonitoring of marine plastic debris should rely on the combination of several bioindicator species with different characteristics that complement each other. Other critical aspects include the standardization of sampling protocols, analytical detection methods and metrics to evaluate the effects of ingested plastics in marine species.
•Few species have been used as bioindicators of marine plastic pollution.•Well-defined spatio-temporal gradients are a prerequisite to using bioindicators.•Toxicity thresholds of plastics ingested by marine organisms need to be set.•Detection methods of ingested plastics need to be standardized.
We investigated the concentration and composition of plastics in 7 Special Areas of Conservation (SACs) from the Gulf of Venice (northern Adriatic Sea). A total of 42 sediment samples were analyzed ...from 21 sites from 2017 to 2018. All sites except one were found to be polluted by plastics, with density ranging between 2250 and 28.4 items kg
−1
. Microplastics ranged from 100 to 61.6% of the collected plastics. Fragments were more represented than filaments. The greatest plastic concentrations were generally recorded in western SACs. Identification through FT-IR spectroscopy evidenced the presence of 8 polymer types: in western SACS, the majority were low-density polymers (PE, PP, PS, and TPU), while in eastern SACs they were high-density polymers (PET, nylon, and PVC). In addition to the role of large rivers (all on the western side of the Gulf) in conveying plastics into the sea, a possible role of the cyclonic water circulation of the northern Adriatic Sea on distribution and composition of plastics along the Gulf coasts is likely.
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•Changes in the structure and abundance of macroalgae.•Long term decline in the number of canopy-forming algal taxa.•Critical loss in the coverage of canopy-forming algal taxa.•Shifts ...from canopy-forming to turf-forming algal taxa.
Canopy-forming macroalgae, especially those belonging to the order Fucales, are creating the so-called brown algal forests that are considered amongst the most productive assemblages in the shallow coastal area. Moreover, they are biological indicators that are used for the assessment of the status of coastal belts according to important European Directives. Along Mediterranean rocky coasts they are disappearing quickly, Cystoseira species (sensu lato) in particular, and are gradually being replaced by turf-forming smaller and persistent algae, due to multiple anthropogenic pressures. The scope of this research was to verify changes in macrophyte structure and abundance, especially canopy-forming taxa, and the loss of Cystoseira s.l. species at two reference sites for macroalgae in the northern Adriatic Sea, during the period 2007–2019. At both sites, the decline of total Cystoseira s.l. spp. coverage (%) was substantial, both in the spring and autumn samples, while some rare and sensitive species were not found during the last surveys. The results of this study should help improving the conservation status of important canopy-forming species, focusing on the revitalisation of benthic critical habitats.
This review investigates the current state of knowledge on the levels of the main essential and non-essential trace elements in Mediterranean vascular plants and macroalgae. The research focuses also ...on the so far known effects of high element concentrations on these marine organisms. The possible use of plants and algae as bioindicators of marine pollution is discussed as well. The presence of trace elements is overall well known in all five Mediterranean vascular plants, whereas current studies investigated element concentrations in only c. 5.0% of all native Mediterranean macroalgae. Although seagrasses and macroalgae can generally accumulate and tolerate high concentrations of trace elements, phytotoxic levels are still not clearly identified for both groups of organisms. Moreover, although the high accumulation of trace elements in seagrasses and macroalgae is considered as a significant risk for the associated food webs, the real magnitude of this risk has not been adequately investigated yet. The current research provides enough scientific evidence that seagrasses and macroalgae may act as effective bioindicators, especially the former for trace elements in sediments, and the latter in seawater. The combined use of seagrasses and macroalgae as bioindicators still lacks validated protocols, whose application should be strongly encouraged to biomonitor exhaustively the presence of trace elements in the abiotic and biotic components of coastal ecosystems.
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•Seagrasses and macroalgae accumulate similar levels of trace elements.•Seagrasses and macroalgae show similar tolerance to high levels of trace elements.•The phytotoxic level of most trace elements is unknown in seagrasses and macroalgae.•Seagrasses and macroalgae act as bioindicators of trace element pollution.•Validated monitoring protocols that combine seagrasses and macroalgae are scarce.
Plastic debris is nowadays a well-recognized global threat to marine ecosystems, due to its increasing abundance and pervasiveness. Although the effects of marine plastics on animal wildlife is ...generally documented, the available studies of plastics affecting seagrasses and their associated biota are relatively scarce. This makes the degree of risk uncertain as regards seagrass ecosystems affected by plastic debris, but also it results in several critical knowledge gaps such as to what extent plastic debris can affect food webs supported by seagrasses. In the age of plastics, the Plasticene, the international political agenda shows great interest in this matter. However, to date, no conservation policies have specifically targeted the protection of seagrasses from plastics debris. Future actions should therefore move in two directions: prompting a radical shift in plastics consumption, and shedding further light on plastics-biota interactions in the marine environment.
•Plastics impact on seagrasses is poorly studied compared to other marine biota.•The effects of plastics-seagrasses interactions are largely unknown.•A critical knowledge gap is plastics impact on food webs supported by seagrasses.•Current political agenda is particularly sensitive to marine plastics pollution.•No anti-plastics regulation aims specifically to protect seagrass ecosystems.
(J. Ellis & Solander) J.V. Lamouroux is the only
species found in the Mediterranean Sea, and it is an important habitat former. In the northern Adriatic,
is among the ten most abundant seaweeds in ...the upper-infralittoral belt in spring and autumn. The modular thalli consist of serially arranged calcified segments. Calcification is closely related to photosynthesis, which causes alkalinization of the inter-utricular space and triggers aragonite formation. Understanding of the complex patterns of segment shape plasticity in relation to CaCO
content at different depth levels is still incomplete. Geometric morphometrics was used to investigate
segment shape variation on the depth transect at Cape Madona Nature Monument in the northern Adriatic Sea. The position on the thallus and the CaCO
content of each studied segment were recorded, allowing slight changes in mineral content to be detected at the microscale of the segments. Our results showed that shape, size, or asymmetry of
segments were not significantly affected by depth. On the other hand, plants that grew deeper were generally more calcified. The apical and subapical segments contributed to the increase in CaCO
content at the deeper sites, whereas the basal segments did not. This indicates that reniform or oval segments positioned apically or subapically play a key role in calcification of
in Mediterranean ecosystems.
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•Estimating marine plastics is difficult for poor uniform approach to quantification.•Lack of standardized definitions of marine microplastics hinders investigation.•Biomagnification ...of plastics is relatively unknown across marine food webs.•Human health will be affected by plastic-contaminated seafood sooner or later.•Legislation should favour prevention by smart disposal of plastics and recycling.
This paper aims to investigate some of the hottest issues that concern the increasing presence of plastics in the sea. In an attempt to identify the main knowledge gaps and to suggest future research, we discuss priority topics on marine plastic pollution through ten thought-provoking questions on the current knowledge of multiple consequences of plastics on the marine ecosystem. Our investigation found that the majority of knowledge gaps include not only intrinsic aspects of plastics (e.g. quantification, typology, fate), but also biological, ecological and legislative implications (e.g. ingestion rate by wildlife, biomagnification across food webs, spread of alien species, consequences for human nutrition, mitigation measures). The current scenario shows that science is still far from assessing the real magnitude of the impact that plastics have on the sea. In particular, the transfer of plastics across marine trophic levels emerged as one of the most critical knowledge gaps. Current regulations seem not sufficient to tackle the massive release of plastics into the sea. Within this complex picture, a positive note is the ever-increasing public awareness. The release of plastics into the sea is certainly a serious environmental issue that can be effectively addressed only through the combined efforts of the three main stakeholders: ordinary citizens through more eco-friendly behaviours, scientists by filling knowledge gaps, and policymakers by passing conservation laws relying on prevention and scientific evidence.
This review analyzes the state of knowledge on the capacity of Mediterranean macroalgae to accumulate, tolerate and biomonitor macro- and micro-elements present in seawater and sediments. The results ...show that the investigated macroalgal species amount to c. 5.0% of all Mediterranean native Rhodophyta, Chlorophyta and Ochrophyta. The most commonly analyzed elements in algae were Pb, Cd, Zn and Cu, whereas very few studies were available for macroelements such as Ca and K. Uptake mechanisms and the factors influencing accumulation are overall well known, but the available studies are restricted to a limited number of chemical elements and algal species. This review also shows that macroalgae can accumulate and tolerate high concentrations of chemical elements, and can act as effective bioindicators of marine pollution. Phytotoxic limits for algal species are not clearly identified by the available studies and require further investigation. Future research should focus on the development of protocols for long-term biomonitoring programmes through the use of macroalgae. Future studies also need to investigate the biomagnification of toxic trace elements in macroalgae-based food webs.
•Chemical element concentrations are known for few Mediterranean macroalgal species.•The relationship between chemical elements in sediments and macroalgae is not clear.•Well-established phytotoxicological limits are lacking for Mediterranean macroalgae.•Macroalgae act as good bioindicators of trace element pollution in seawater.•Trace element biomonitoring with macroalgae needs validated protocols.
The present research compared the capability of the green seaweed Ulva lactuca and the seagrass Posidonia oceanica to accumulate and biomonitor the levels of six trace elements: Cd, Cr, Cu, Ni, Pb, ...Zn. The concentrations of these elements were analyzed in seawater, bottom sediments, U. lactuca thalli and P. oceanica leaves, in four sites of Sicily (Italy) with different levels of pollution. The results showed that P. oceanica is able to accumulate greater concentrations of trace elements compared to U. lactuca. Both species, instead, acted equally as good bioindicators of marine pollution, showing significant correlations with the levels of trace elements in the surrounding environment. The use of P. oceanica and U. lactuca as bioindicators is still limited in biomonitoring programs, and should be further encouraged given the ever-increasing marine pollution.
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•Posidonia oceanica and Ulva lactuca can accumulate high levels of trace elements.•P. oceanica shows higher concentrations of trace elements than U. lactuca.•The influence of salinity, temperature and pH was minor in species element levels.•P. oceanica and U. lactuca perform equally well as bioindicators of trace elements.•P. oceanica and U. lactuca are not sufficiently used for sea pollution monitoring.
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