Monk seal faeces as a non-invasive technique to monitor the incidence of ingested microplastics and potential presence of plastic additives.

Anthropogenic debris, including plastics, has recently been identified as a major threat for marine mammals and the Marine Strategy Framework Directive aims to achieve the good environmental status of European waters by addressing among other criteria, the effects of marine litter on biota. This study implemented for the first time a non-invasive technique for collecting monk seal samples to assess microdebris ingestion in combination with identifying plastic additives and porphyrins biomarkers. A total of 12 samples of monk seal faeces were collected from marine caves in Zakynthos Island, Greece. A total of 166 microplastic particles were identified; 75 % of the particles were smaller than 3 mm. Nine phthalates and three porphyrins were detected. A strong correlation was found between the number of microplastics and the concentration of phthalates. The values of both phthalates and porphyrins were found lower than in other marine mammal tissues, suggesting that seals might not be impacted by them yet.

First Documented Uses of Caves along the Coast of Albania by Mediterranean Monk Seals (Monachus monachus, Hermann 1779): Ecological and Conservation Inferences.

Information on the habitat use of the Mediterranean monk seal (Monachus monachus) along the coast of Albania (Adriatic and Ionian Sea) has so far been limited to vague and generalised data. A survey conducted in the National Marine Park Karaburun-Sazan in the summer of 2019 identified two marine caves with morphological characteristics best suited for use by such species. The two caves were subsequently equipped with infrared camera traps in 2020. The recovery of a scat in one of the caves during the 2019 survey and the photographic material obtained confirmed the use of the cave. This research provides the first documentation of marine cave habitat use by the Mediterranean monk seal in Albania. Quantitative and qualitative assessment of specimens frequenting the area could not be performed due to the limited data obtained on seal presence along the Albanian coasts. Nevertheless, the retrieved information is relevant for Albania and for the species conservation. The collected scat was analysed for trophic and anthropogenic contamination data. Three species (gilthead sea bream, European sea bass, and garfish), as well as four anthropogenic items (including a piece of nylon net), were identified. The inferences resulting from the analyses of the data presented in this study provided additional information on the ecology of the species and its conservation priorities, which need to be contextualized at the Adriatic-Ionian regional scale.

Microplastic Extraction from Marine Vertebrate Digestive Tracts, Regurgitates and Scats: A Protocol for Researchers from All Experience Levels.

It is essential to provide a protocol for the separation and identification of microplastics in marine vertebrates (mammals, birds, turtles and fish) that is easy to follow and adaptable depending on research infrastructure. Digesting organic material is an effective way to analyze samples for microplastics. Presented here is an optimized protocol which uses potassium hydroxide (KOH) for processing samples of digestive tracts, scats and regurgitates. KOH is a cheap, effective and simple alkaline digestant that allows extraction of plastics from the sample matrix. Samples are first digested, then filtered before visual and chemical analysis of remaining particle. This allows size, shape, color and polymer of each particle to be ascertained. This protocol has been harmonized with other protocols for the collection of different samples (e.g., diet, parasites, other pathologies). The implementation of this protocol at different levels of economic and/or laboratory resources make information on microplastic incidence available to the entire research community.

Incidence of marine debris in cetaceans stranded and bycaught in Ireland: Recent findings and a review of historical knowledge.

Interactions between marine mammals and plastic debris have been the focus of studies for many years. Examples of interactions include entanglement in discarded fishing items or the presence of ingested debris in digestive tracts. Plastics, including microplastics, are a form of marine debris globally distributed in coastal areas, oceanic waters and deep seas. Cetaceans which strand along the coast present a unique opportunity to study interactions between animals with macro- and microplastics. A combination of novel techniques and a review of historical data was used to complete an extensive study of cetaceans interacting with marine debris within Irish waters. Of the 25 species of marine mammals reported in Irish waters, at least 19 species were reported stranded between 1990 and 2015 (n = 2934). Two hundred and forty-one of the stranded cetaceans presented signs of possible entanglement or interactions with fisheries. Of this number, 52.7% were positively identified as bycatch or as entangled in fisheries items, 26.6% were classified as mutilated and 20.7% could not be related to fisheries but showed signs of entanglement. In addition, 274 cetaceans were recorded as by-catch during observer programmes targeting albacore tuna. Post-mortem examinations were carried out on a total of 528 stranded and bycaught individuals and 45 (8.5%) had marine debris in their digestive tracts: 21 contained macrodebris, 21 contained microdebris and three had both macro- and microdebris. Forty percent of the ingested debris were fisheries related items. All 21 individuals investigated with the novel method for microplastics contained microplastics, composed of fibres (83.6%) and fragments (16.4%). Deep diving species presented more incidences of macrodebris ingestion but it was not possible to investigate this relationship to ecological habitat. More research on the plastic implications to higher trophic level organisms is required to understand the effects of these pollutants.

Microplastic and macroplastic ingestion by a deep diving, oceanic cetacean: the True's beaked whale Mesoplodon mirus.

When mammals strand, they present a unique opportunity to obtain insights into their ecology. In May 2013, three True's beaked whales (two adult females and a female calf) stranded on the north and west coasts of Ireland and the contents of their stomachs and intestines were analysed for anthropogenic debris. A method for identifying microplastics ingested by larger marine organisms was developed. Microplastics were identified throughout the digestive tract of the single whale that was examined for the presence of microplastics. The two adult females had macroplastic items in their stomachs. Food remains recovered from the adult whales consisted of mesopelagic fish (Benthosema glaciale, Nansenia spp., Chauliodius sloani) and cephalopods, although trophic transfer has been discussed, it was not possible to ascertain whether prey were the source of microplastics. This is the first study to directly identify microplastics <5 mm in a cetacean species.

Ultrastructure of the Odontocete organ of Corti: scanning and transmission electron microscopy.

The morphological study of the Odontocete organ of Corti, together with possible alterations associated with damage from sound exposure, represents a key conservation approach to assess the effects of acoustic pollution on marine ecosystems. By collaborating with stranding networks from several European countries, 150 ears from 13 species of Odontocetes were collected and analyzed by scanning (SEM) and transmission (TEM) electron microscopy. Based on our analyses, we first describe and compare Odontocete cochlear structures and then propose a diagnostic method to identify inner ear alterations in stranded individuals. The two species analyzed by TEM (Phocoena phocoena and Stenella coeruleoalba) showed morphological characteristics in the lower basal turn of high-frequency hearing species. Among other striking features, outer hair cell bodies were extremely small and were strongly attached to Deiters cells. Such morphological characteristics, shared with horseshoe bats, suggest that there has been convergent evolution of sound reception mechanisms among echolocating species. Despite possible autolytic artifacts due to technical and experimental constraints, the SEM analysis allowed us to detect the presence of scarring processes resulting from the disappearance of outer hair cells from the epithelium. In addition, in contrast to the rapid decomposition process of the sensory epithelium after death (especially of the inner hair cells), the tectorial membrane appeared to be more resistant to postmortem autolysis effects. Analysis of the stereocilia imprint pattern at the undersurface of the tectorial membrane may provide a way to detect possible ultrastructural alterations of the hair cell stereocilia by mirroring them on the tectorial membrane.

Species effects on ecosystem processes are modified by faunal responses to habitat composition.

Heterogeneity is a well-recognized feature of natural environments, and the spatial distribution and movement of individual species is primarily driven by resource requirements. In laboratory experiments designed to explore how different species drive ecosystem processes, such as nutrient release, habitat heterogeneity is often seen as something which must be rigorously controlled for. Most small experimental systems are therefore spatially homogeneous, and the link between environmental heterogeneity and its effects on the redistribution of individuals and species, and on ecosystem processes, has not been fully explored. In this paper, we used a mesocosm system to investigate the relationship between habitat composition, species movement and sediment nutrient release for each of four functionally contrasting species of marine benthic invertebrate macrofauna. For each species, various habitat configurations were generated by selectively enriching patches of sediment with macroalgae, a natural source of spatial variability in intertidal mudflats. We found that the direction and extent of faunal movement between patches differs with species identity, density and habitat composition. Combinations of these factors lead to concomitant changes in nutrient release, such that habitat composition effects are modified by species identity (in the case of NH4-N) and by species density (in the case of PO4-P). It is clear that failure to accommodate natural patterns of spatial heterogeneity in such studies may result in an incomplete understanding of system behaviour. This will be particularly important for future experiments designed to explore the effects of species richness on ecosystem processes, where the complex interactions reported here for single species may be compounded when species are brought together in multi-species combinations.

Influence of macrofaunal assemblages and environmental heterogeneity on microphytobenthic production in experimental systems.

Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment-water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production.