Laboratory culture and evaluation of the tubeworm Ficopomatus enigmaticus for biofouling studies

Heterocyclic Group Functionalized Siloxane-Based Polymers for Interruption of pH-Dependent Marine Settlement

Marine biofouling is the natural accumulation of organisms on substrates that reside in rivers, lakes, and seas. To combat this issue, polymer-based coatings historically utilized tin or copper compounds, which, though effective, are also highly toxic. In this study, a series of functionalized toxicant-free PDMS-type polymers were designed with pH buffer and zwitterionic moieties for fouling inhibition. The water contact angles ranged from 41 to 98°, demonstrating significant differences in the wettability of the coated surfaces. XPS and SEM-EDS testing confirmed the surface presence of buffer and zwitterionic functional groups. Assays were carried out using both laboratory and field testing against an array of marine species to gain an understanding of how these buffered polymer coatings hold up in the environment and to measure their antifouling and fouling-release capabilities. The organisms used for testing were a diatom, Navicula incerta, and two types of tubeworms, spirorbid and nonspirorbid serpulids. Piperazine and piperazine zwitterionic-based coatings performed the best overall as antifouling and fouling-release materials. Preliminary biological assays suggest that hydrophobic zwitterion-functionalized siloxane-based polymers may have both preventative antibacterial and antifouling interactions with target species compared to previously studied hydrophobic materials.

Interrupting marine fouling with active buffered coatings

Biofouling on marine surfaces causes immense material and financial harm for maritime vessels and related marine industries. Previous reports have shown the effectiveness of amphiphilic coating systems based on poly(dimethylsiloxane) (PDMS) against such marine foulers. Recent studies on biofouling mechanisms have also demonstrated acidic microenvironments in biofilms and stronger adhesion at low-pH conditions. This report presents the design and utilization of amphiphilic polymer coatings with buffer functionalities as an active disruptor against four different marine foulers. Specifically, this study explores both neutral and zwitterionic buffer systems for marine coatings, offering insights into coating design. Overall, these buffer systems were found to improve foulant removal, and unexpectedly were the most effective against the diatom Navicula incerta.

Nitroxide-Containing Amphiphilic Random Terpolymers for Marine Antifouling and Fouling-Release Coatings

Two types of amphiphilic random terpolymers, poly(ethylene glycol methyl ether methacrylate)-ran-poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate)-ran-poly(polydimethyl siloxane methacrylate) (PEGMEMA-r-PTMA-r-PDMSMA), were synthesized and evaluated for antifouling (AF) and fouling-release (FR) properties using diverse marine fouling organisms. In the first stage of production, the two respective precursor amine terpolymers containing (2,2,6,6-tetramethyl-4-piperidyl methacrylate) units (PEGMEMA-r-PTMPM-r-PDMSMA) were synthesized by atom transfer radical polymerization using various comonomer ratios and two initiators: alkyl halide and fluoroalkyl halide. In the second stage, these were selectively oxidized to introduce nitroxide radical functionalities. Finally, the terpolymers were incorporated into a PDMS host matrix to create coatings. AF and FR properties were examined using the alga Ulva linza, the barnacle Balanus improvisus, and the tubeworm Ficopomatus enigmaticus. The effects of comonomer ratios on surface properties and fouling assay results for each set of coatings are discussed in detail. There were marked differences in the effectiveness of these systems against the different fouling organisms. The terpolymers had distinct advantages over monopolymeric systems across the different organisms, and the nonfluorinated PEG and nitroxide combination was identified as the most effective formulation against B. improvisus and F. enigmaticus.

FEATURES OF THE BIOLOGY OF THE POLYCHETE <i>FICOPOMATUS ENIGMATICUS</i> (FAUVEL, 1923) FROM MASS SETTLEMENTS IN THE COASTAL WATERS OF THE KERCH STRAIT (BLACK SEA)

In September 2019, the polychaeta (Fauvel, 1923), formerly known as Fauvel, 1923, was found in mass colonial settlements in the coastal waters of the Kerch Strait near the Arshintsevskaya Spit. Some workers believe that the original natural distribution of this polychaeta was in brackish water bodies of India. This species is currently known to be widely distributed along the coasts of the Atlantic, Pacific, and Indian Oceans, and of the North, Mediterranean, and Caspian Seas. Only a few isolated individuals of have been found so far along the Crimean coast of the Black Sea, in the coastal zone of Sebastopol and along the Karadag shores. The colonies described in this study do not constitute reef structures yet but have already reached high population numbers. The colony have a diameter of 46 cm and comprise 1774 individuals. The settlements of are true populations represented by individuals of different sizes ranging in length from 2 to 39 mm. The populations include both males and females: males comprise 56% and females 44% of the population. The fecundity of the worms expressed as the number of mature eggs per female depends on the body size and ranges from 5800 eggs for the body size of 12 mm to 24820 eggs for the body size of 29 mm. The present study described the morphology of using scanning electron microscopy and identified numerous sensory structures on the surface of the body, gills and the pygidium for the first time. Judging from the presence of a mass settlement of the polychaeta in the coastal waters of the Kerch Strait, it can be presumed that this species has become completely naturalized in the Black Sea. Since this species is eurybiontic, it can be assumed that it will invade the Sea of Azov and adjacent estuaries, river deltas and coastal lakes successfully, which will have an inevitable effect on the life of the local species and the ecosystems in general.

Laser ablation of the apical sensory organ of Hydroides elegans (Polychaeta) does not inhibit detection of metamorphic cues

Larvae of many marine invertebrates bear an anteriorly positioned apical sensory organ (ASO) presumed to be the receptor for settlement- and metamorphosis-inducing environmental cues, based on its structure, position and observed larval behavior. Larvae of the polychaete Hydroides elegans are induced to settle by bacterial biofilms, which they explore with their ASO and surrounding anteroventral surfaces. A micro-laser was utilized to destroy the ASO and other anterior ciliary structures in competent larvae of H. elegans. After ablation, larvae were challenged with bacterial biofilmed or clean surfaces and percentage metamorphosis was determined. Ablated larvae were also assessed for cellular damage by applying fluorescently tagged FMRF-amide antibodies and observing the larvae by laser-scanning confocal microscopy. While the laser pulses caused extensive damage to the ASO and surrounding cells, they did not inhibit metamorphosis. We conclude that the ASO is not a required receptor site for cues that induce metamorphosis.

A data-driven approach to predicting the attachment density of biofouling organisms

The attachment efficiency of biofouling organisms on solid surfaces depends on a variety of factors, including fouler species, nutrition abundance, flow rate, surface morphology and the stiffness of the solid to which attachment is to be made. So far, extensive research has been carried out to investigate the effects of these factors on the attachment of various fouling species. However, the results obtained are species-dependent and scattered. There is no universal rule that can be applied to predict the attachment efficiency of different species. To solve this problem, the authors carried out meta-analysis of the effects of ten selected factors on attachment efficiency, resulting in a universal correlation between the attachment density and the selected factors, which was validated by attachment tests of tubeworms on PDMS surfaces. The results provide a practical approach to predicting the attachment efficiency of fouling organisms and should be of great value in the design of anti-biofouling materials.

Soluble esterases as biomarkers of neurotoxic compounds in the widespread serpulid Ficopomatus enigmaticus (Fauvel, 1923)

The characterization of soluble cholinesterases (ChEs) together with carboxylesterases (CEs) in Ficopomatus enigmaticus as suitable biomarkers of neurotoxicity was the main aim of this study. ChEs of F. enigmaticus were characterized considering enzymatic activity, substrate affinity (acetyl-, butyryl-, propionylthiocholine), kinetic parameters (K_m and V_max) and in vitro response to model inhibitors (eserine hemisulfate, iso-OMPA, BW284C51), and carbamates (carbofuran, methomyl, aldicarb, and carbaryl). CEs were characterized based on enzymatic activity, kinetic parameters and in vitro response to carbamates (carbofuran, methomyl, aldicarb, and carbaryl). Results showed that cholinesterases from F. enigmaticus showed a substrate preference for acetylthiocholine followed by propionylthiocholine; butyrylthioline was not hydrolyzed differently from other Annelida species. CE activity was in the same range of cholinesterase activity with acetylthiocholine as substrate; the enzyme activity showed high affinity for the substrate p-nytrophenyl butyrate. Carbamates inhibited ChE activity with propionylthiocholine as substrate to a higher extent than with acetylthiocoline. Also CE activity was inhibited by all tested carbamates except carbaryl. In vitro data highlighted the presence of active forms of ChEs and CEs in F. enigmaticus that could potentially be inhibited by pesticides at environmentally relevant concentration.

Toxicity evaluation of carboxylated carbon nanotubes to the reef-forming tubeworm Ficopomatus enigmaticus (Fauvel, 1923)

In recent years, oxidative stress has been recognized as one of the most common effects of nanoparticles in different organisms. Ficopomatus enigmaticus (Fauvel, 1923), a member of a large family of serpulidae polychates, is an important encrusting organism in a diverse set of marine habitats, from harbours to coral reefs. This species has been previously studied for ecotoxicological purposes, despite the lack of reported studies on this species biochemical response after exposure to different pollutants. For these reasons, and for the first time, a set of biomarkers related to oxidative status were assessed in polychaetes after 28 days of exposure. Furthermore, polychaetes metabolic performance and potential neurotoxicity were investigated. Results clearly demonstrated induced toxicity in the filter-feeder polychaetes after exposure to nanoparticles. Indeed, CNTs altered the biochemical and physiological status of F. enigmaticus, both in terms of energy reserves (reduction of protein and glycogen contents), oxidative status (expressed as damage in cell function such as protein carbonyl content and lipid peroxidation) and activation of antioxidant enzymes defences (Glutathione reductase, Catalase, Glutathione peroxidase and Glutathione S-transferases activities). The present study showed for the first time that this species can be used as a model organism for nanoparticle toxicology.

The serpulid Ficopomatus enigmaticus () as candidate organisms for ecotoxicological assays in brackish and marine waters

Ficopomatus enigmaticus is an ubiquitous fouling reef-forming species, easy to sample and recognize, diecious with gamete spawning along different seasons in different salinity conditions. Due to its characteristics it could become a good candidate for the monitoring of both marine and brackish waters. The suitability of F. enigmaticus as a promising model organism in ecotoxicological bioassays was evaluated by a sperm toxicity and a larval development assay. The fertilization rate in different salinity conditions (range 5-35‰) was first assessed in order to detect the salinity threshold within which profitably perform the assays. Afterward copper (Cu²⁺), cadmium (Cd²⁺), sodium dodecyl sulfate (SDS) and 4-n-nonylphenol (NP) were used as reference toxicants in exposure experiments with spermatozoids (sperm toxicity assay) and zygotes (larval development assay). A dose-response effect was obtained for all tested toxicants along all salinity conditions except for 5‰ salinity condition where a too low (<30%) fertilization rate was observed. NP showed the highest degree of toxicity both in sperm toxicity and larval development assay. In some cases the results, expressed as EC₅₀ values at 35‰ salinity condition, were similar to those observed in the literature for marine organisms such as the sea urchin (Paracentrotus lividus) and the marine serpulid Hydroides elegans, while the exposure of F. enigmaticus spermatozoids' to Cd²⁺ and NP resulted in toxicity effects several orders of magnitude higher than observed in P. lividus. Spermatozoids resulted to be slightly more sensitive then zygotes to all different toxicants.

Photopolymerized Network Polysiloxane Films with Dangling Hydrophilic/Hydrophobic Chains for the Biofouling Release of Invasive Marine Serpulid Ficopomatus enigmaticus

Novel photopolymerized network films based on a polysiloxane matrix containing varied amounts of polyoxyethylene (P3) or perfluorohexylethyl (F) dangling side chains were investigated. For films containing less than 10 wt % P3 and F, the wettability and elastic modulus were similar to those of the photopolymerized network matrix. However, angle-resolved X-ray photoelectron spectroscopy measurements proved that the surface of films with F dangling chains was highly enriched in fluorine depending on both the amount of P3 and F and their relative ratio in the films. The biological performance of the films was evaluated against a new widespread and invasive marine biofoulant, the serpulid Ficopomatus enigmaticus. The diatom Navicula salinicola was also assayed as a conventional model organism for comparison. Films richer in P3 better resisted the settlement and promoted the release of calcified tubeworms of F. enigmaticus.