Small Marine Research Articles

Reef fish biodiversity and occurrence of endangered sharks within a small marine protected area off Sint Maarten, Dutch Caribbean

AbstractMarine protected areas (MPAs) are common conservation tools supporting the protection of threatened marine fishes, such as sharks. However, the creation of shark MPAs has been less common in the Greater Caribbean region despite a growing need and opportunity. In this study, we evaluated the occurrence of shark and reef fish biodiversity off Sint Maarten, Dutch Caribbean, with a particular emphasis on endangered shark presence within the Man of War Shoal Marine Protected Area (MPA). We utilized baited remote underwater video systems (BRUVs) to gather non-invasive data on the abundance and diversity of reef fish and shark species inside and outside the local MPA. Generalized linear models (GLMs) revealed no significant effect of protection status on the presence of the endangered Caribbean reef shark (Carcharhinus perezi). However, we found a significant influence of depth on shark occurrence, as well as an effect of habitat type on shark and reef fish biodiversity, with reef habitats showing the greatest significance. These results suggest that the effect of small coastal MPAs on bolstering local endangered species conservation in the Dutch Caribbean is likely to vary according to habitat features and how those species utilize those habitats across various life stages. These findings have implications for adaptive MPA management, which should be informed by the ecology and habitat preferences of target species to achieve maximum benefits for biodiversity conservation.

Armed on the back: Hidden biomineralized scales in the ventral girdle of chiton Acanthopleura loochooana

Flexible protective armors are found in large animals such as fish skins, snake skins, and pangolin scales. For small-sized invertebrates, such armors are paid less attention and overlooked. Chitons, a type of marine mollusk, possess mineralized armors covering the whole dorsal body. The dorsal scales in the girdle tissue are well known, in this study, we reported hidden mineralized scales in the ventral side of chiton Acanthopleura loochooana girdles for the first time. The ventral surface is covered with scales with ca. 40 μm in length, forming continuous but overlapped scales. Additionally, scales are formed from aragonitic spicule-like and square-like scales, embedded in the cuticle layer. Nanoindentation testing results showed that the hardness and elastic modulus of ventral scales were ∼20 % higher compared to those in the dorsal scales, exhibiting good hardness and wear resistance. The combination of the ventral scales and cuticle, along with the regular arrangement of ventral scales, may allow chitons to simultaneously address complex and variable attachment interfaces while also providing wear-resistant protection. This study provides insights for designing protective structures that balance flexibility and durability. Statement of significanceBiomineralization is universal in nature and provides protection and support for animals. However, mineralization of dermal skin is not commonly seen. Herein, for the first time, we reported hidden minerals covering the whole ventral side of skin in a small marine animal, chitons. Calcium carbonate minerals are arranged regularly and manifest different morphology in different regions. Additionally, these minerals are embedded in a continuous cuticle layer covering the whole animal. The material also indicates a higher wear-resistant property. This study extends our understanding of the diverse functionality of biominerals and provides a prototype for designing wear-resistant materials.

Ретроспективный сравнительный анализ эффективности хондропротективной терапии пациентов с хронической болью в нижней части спины

INTRODUCTION. The choice of optimal therapy for chronic lower back pain includes: influence on all links of the pain vicious circle, has analgesic and anti-inflammatory effects, chondroprotective effect. AIM. A retrospective comparative analysis of outpatient records of patients with chronic lower back pain with a course of therapy with drugs containing chondroitin sulfate – Chondroguard, and bioactive concentrate of small marine fish – Alflutop. MATERIAL AND METHODS. Outpatient records of patients who took Chondroguard and Alflutop in the period from January 2022 to April 2024 were included. Data from 60 patients (medium age 51.5±9.7 years). Patients were retrospectively divided into two groups depending on the strategy of pain management. The main group (n=30; medium age 51.0±9.8 years), who received Chondroguard intramuscularly (I/ m) every other day No. 25 according to the scheme: the first 3 injections (1st, 3rd, 5th day) - 1 ml (100 mg), with good tolerability from the 4th injection (7 day) – 2 ml (200 mg); and the Comparison group (n=30; medium age 49.3±9.9 years), received Alflutop 2 ml, 1 time a day, every other day, a short course of 10 days. The dynamics of the condition was assessed on days 10, 20, 50. RESULTS AND DISCUSSION. By day 50 in the Main group, there was a decrease in pain by an average of 86.6% according to the numerical rating scale and an improvement in the functional status according to the Oswestry scale of 95.5%, in the comparison group there was a decrease in pain by an average of 77.2%, an improvement in the functional status according to Oswestry scale of 86.7%. By day 50, the severity of pain syndrome in the Main group decreased by 91.2%, in the Comparison group – by 33.9%; indicators of the functional status of Oswestry scale in the Main group improved by 97.3%, in the Comparison group – by 84.8%. In the Main group, the need for multiple nonsteroidal anti-inflammatory drugs on the 10th day of therapy decreased to 1 tablet per day in 76.7%, in the Comparison group – in 16.7%. In the main group, after a course of therapy for 21.3±2.2 months. they did not consult a doctor in the comparison group after 5.3±1.1 months. A second course of therapy was conducted. CONCLUSION. In the Main group, the effects of therapy can be regarded as long-term, since the effects of highly purified chondroitin sulfate on the pathogenetic mechanisms of the formation of chronic lower back pain remain. KEYWORDS: pain syndrome, lower back pain, chondroitin sulfate, Chondroguard

A matter of scale: Identifying the best spatial and temporal scale of environmental variables to model the distribution of a small cetacean.

The importance of scale when investigating ecological patterns and processes is recognised across many species. In marine ecosystems, the processes that drive species distribution have a hierarchical structure over multiple nested spatial and temporal scales. Hence, multi-scale approaches should be considered when developing accurate distribution models to identify key habitats, particularly for populations of conservation concern. Here, we propose a modelling procedure to identify the best spatial and temporal scale for each modelled and remotely sensed oceanographic variable to model harbour porpoise (Phocoena phocoena) distribution within the Irish Exclusive Economic Zone. Harbour porpoise sightings were recorded during dedicated line-transect aerial surveys conducted in the summers of 2016, 2021 and 2022. Binary generalised additive models were used to assess the relationships between porpoise presence and oceanographic variables at different spatial (5-40 km) and temporal (daily, monthly and across survey period) scales. Selected variables included sea surface temperature, thermal fronts, chlorophyll-a, sea surface height, mixed layer depth and salinity. A total of 30,514 km was covered on-effort with 216 harbour porpoise sightings recorded. Overall, the best spatial scale corresponded to the coarsest resolution considered in this study (40 km), while porpoise presence showed stronger association with oceanographic variables summarised at a longer temporal scale. Habitat models including covariates at coarse spatial and temporal scales may better reflect the processes driving availability and abundance of resources at these large scales. These findings support the hypothesis that a multi-scale approach should be applied when investigating species distribution. Identifying suitable spatial and temporal scale would improve the functional interpretation of the underlying relationships, particularly when studying how a small marine predator interacts with its environment and responds to climate and ecosystem changes.

Marine Debris Harbor Unique, yet Functionally Similar Cryptofauna Communities.

Human-made debris is entering the ocean at alarming rates. These artificial structures are becoming habitats for small marine taxa known as cryptofauna. Cryptofauna are among the most essential reef taxa; however, little is known about these organisms, let alone their fate considering degrading coral reefs and increasing anthropogenic disturbance. The current study explores differences in naturally occurring cryptofauna biodiversity compared to those inhabiting benthic marine debris. To explore this difference, we measured invertebrate diversity from autonomous reef monitoring structures (ARMS) located on patch reefs along the middle Florida Keys reef tract. ARMS were used as a proxy for natural structure to compare to marine debris removed from five reef locations. Plastic debris was the most abundant of all the debris material collected. Wood and concrete were identified as covariates since they are sourced from wooden lobster traps. Taxa diversity varied significantly between ARMS and debris, indicating that each structural unit contained significantly different and diverse communities. The most influential taxa identified included commensal shrimps, hermit crabs, brittle stars, segmented worms, and several families of crabs. Additionally, while functional richness increased with taxa richness for ARMS communities, debris communities showed decreasing functional richness and high functional similarity, suggesting a specialization of debris-specific taxa. Overall, these data assist in better understanding of the marine community ecology surrounding anthropogenic marine debris for future debris removal and management practices for comprehensive reef health.

A new species of Paranerilla Jouin & Swedmark, 1965 (Annelida: Polychaeta) from Brazil

Nerillids are small marine annelids, once placed at the artificial group ‘Archiannelida’, which contained all families of the exclusively interstitial polychaetes. Nerillidae is the most species rich family among them, with 71 species grouped into 15 genera, and represents an important component of the interstitial fauna, occupying a wide bathymetric range. Despite its problematic placement among the ‘Archiannelida’ families, the group per se is considered monophyletic. Currently, only two species of Paranerilla are valid, both being reported from the northern hemisphere. It is presented herein as the first description of a species of Paranerilla from tropical waters, named as Paranerilla schiavettii sp. nov., which is also considered as a unique record by the presence of a modified acicular spine in noto- and neuropodia from chaetiger 3–7, not mentioned in its congeners descriptions. Hence, we also propose an emendation on the genus diagnosis to embrace the presence of acicular spines within Paranerilla. So, the presented information complements the current knowledge about the group’s taxonomy and expands its distribution to South Atlantic waters.

Brute force prey metabarcoding to explore the diets of small invertebrates.

Prey metabarcoding has become a popular tool in molecular ecology for resolving trophic interactions at high resolution, from various sample types and animals. To date, most predator-prey studies of small-sized animals (<1 mm) have met the problem of overabundant predator DNA in dietary samples by adding blocking primers/peptide nucleic acids. These primers aim to limit the PCR amplification and detection of the predator DNA but may introduce bias to the prey composition identified by interacting with sequences that are similar to those of the predator. Here we demonstrate the use of an alternative method to explore the prey of small marine copepods using whole-body DNA extracts and deep, brute force metabarcoding of an 18S rDNA fragment. After processing and curating raw data from two sequencing runs of varying depths (0.4 and 5.4 billion raw reads), we isolated 1.3 and 52.2 million prey reads, with average depths of ~15,900 and ~120,000 prey reads per copepod individual, respectively. While data from both sequencing runs were sufficient to distinguish dietary compositions from disparate seasons, locations, and copepod species, greater sequencing depth led to better separation of clusters. As computation and sequencing are becoming ever more powerful and affordable, we expect the brute force approach to become a general standard for prey metabarcoding, as it offers a simple and affordable solution to consumers that is impractical to dissect or unknown to science.

Analysis of Integrated Coastal Management (ICM) of El Salvador

The Republic of El Salvador has a small marine coastal zone that is deteriorated by uncontrolled anthropogenic activities; the implementation of an integrated coastal management program (ICM) is necessary to mitigate the damage caused to marine zones and the performance of coastal governance to provide sustainable development. The purpose of this study is collect information on policies, laws and instruments that focus on the conservation and development of the coastal marine areas of El Salvador. Keywords: Integrated Coastal Management (icm), coastal policies, coastal conservation, development of the coastal zone, El Salvador.

Pre-Processing of Simulated Synthetic Aperture Radar Image Scenes Using Polarimetric Enhancement for Improved Ship Wake Detection

Ship wake detection using synthetic aperture radar (SAR) imagery provides a way to obtain small marine ship information, but it often becomes unavailable and unreliable during a high sea state. Polarimetric information provides a potential way to solve this problem, which can enhance the ship target as well as the ship wake features. However, three challenges still exist in ship wake detection in polarimetric SAR imagery: the unwanted influences of bright and singular points on ship wake detection, the lack of performance analysis of wake detection by new-type polarimetric enhancement methods, and the difficulty of using the assessment criteria for ship wake detection. In this paper, we try to solve the above problems. Firstly, fully polarized SAR imagery of both ship turbulent and Kelvin wake is simulated based on the two-scale composite model, and the Polarimetric Whitening Filter (PWF) and Polarimetric Detection Optimization Filter (PDOF) are applied to the simulated fully polarized SAR imagery to enhance the ship wake features. Secondly, since the bright and singular points resulting from the ship echoes and the polarimetric enhancement methods may lead to misdetections, a logarithm process and z-score normalization pre-processing has been applied to the images. Then, a new assessment criterion for wake detection performance has been formulated, and the probability of missing detections (PMDs) and the probability of false alarms (PFAs) have been defined for two different requirements. And a Radon transform-based ship wake detection method for both ship turbulence and Kelvin wake has been carried out in horizontal–horizontal (HH), vertical–vertical (VV), horizontal–vertical (HV), PWF and PDOF SAR imagery. Finally, an analysis of the wake detection performance has been carried out. The PWF and PDOF can improve the wake detection performance by an average of nearly 50 percent compared with the HH and VV.

Phage-inducible chromosomal minimalist islands (PICMIs), a novel family of small marine satellites of virulent phages

Phage satellites are bacterial genetic elements that co-opt phage machinery for their own dissemination. Here we identify a family of satellites, named Phage-Inducible Chromosomal Minimalist Islands (PICMIs), that are broadly distributed in marine bacteria of the family Vibrionaceae. A typical PICMI is characterized by reduced gene content, does not encode genes for capsid remodelling, and packages its DNA as a concatemer. PICMIs integrate in the bacterial host genome next to the fis regulator, and encode three core proteins necessary for excision and replication. PICMIs are dependent on virulent phage particles to spread to other bacteria, and protect their hosts from other competitive phages without interfering with their helper phage. Thus, our work broadens our understanding of phage satellites and narrows down the minimal number of functions necessary to hijack a tailed phage.

LPG, Gasoline, and Diesel Engines for Small Marine Vessels: A Comparative Analysis of Eco-Friendliness and Economic Feasibility

As an escalating global concern for environmentally sustainable marine fuels, liquefied petroleum gas (LPG) is attracting attention as an eco-friendly and economical alternative. This study explored LPG utilization in small marine vessels, focusing on its eco-friendliness and economic feasibility. To assess its environmental implications, the AVL FIRE simulation program was used to compare CO2, CO, NO, and soot emissions from LPG engines with those from conventional gasoline and diesel engines. The LPG engine model relied on data from a pioneering type-approved experimental LPG engine designed for small South Korean marine vessels, while parameters for gasoline and diesel engines were adjusted to suit their distinctive features. Regarding long-term economic feasibility, assuming a 30-year ship lifespan, incorporating 2022 annual average prices, average annual price growth rates, and annual fuel consumption data of each fuel, results indicate that LPG engines exhibited lower CO2, CO, NO, and soot emissions than conventional engines, except that NO emissions were higher than gasoline engines. Evaluating LPG’s economic feasibility over a 30-year ship life cycle for an individual vessel revealed varying fuel cost savings, with the greatest savings observed in gasoline–other (KRW 2220.7 million) and the least in gasoline–coastal (KRW 1152.5 million). These findings offer vital insights for ship operators and policymakers seeking a balance between eco-friendliness and cost-effectiveness, as well as LPG engine technology emerging as pivotal for a sustainable future, harmonizing environmental protection and economic viability.

Assessing the Effect of Wind on the Motion Peaks of Small Marine Vessels

Assessing the Effect of Wind on the Motion Peaks of Small Marine Vessels

Elasmobranch diversity around the southern Caribbean island of Tobago: opportunities for conservation in a regional trade hub

Abstract Sharks are scarce in much of the Caribbean due to widespread depletion. Trinidad and Tobago, in the southern Caribbean, is a shark meat consumer and international exporter of dried shark fins. Despite limited fisheries management there is a small Marine Protected Area (MPA; 7 km2) in urbanised southwest Tobago, but its effect on sharks and rays (elasmobranchs) is unknown. The rural northeast is a recently designated UNESCO Man and the Biosphere Reserve with a significant marine component and plans for a large MPA, but no baseline data for elasmobranchs exist. Given the local importance of elasmobranchs and a newly drafted Sustainable Shark and Ray Management Plan, we used baited remote underwater video stations within a 40 m depth contour at 270 randomly generated points around Tobago to: (i) establish a baseline of species richness and relative abundance, (ii) investigate the influence of season, habitat relief, depth and water temperature on relative abundance, and (iii) investigate spatial variation in relative abundance. Caribbean reef sharks, nurse sharks, and southern stingrays were observed at all sites, the latter two more frequently in the urbanised southwest. Shark diversity was unexpectedly high in the northeast, driven by rarer species (sharpnose, smoothhound, tiger, scalloped hammerhead, great hammerhead) only observed there. Habitat relief, depth and season likely influence relative abundance of elasmobranchs around Tobago, but research is needed to elucidate species-level effects. Shark species richness in northeast Tobago is high for the Caribbean, warranting research attention, while the larger MPA presents an opportunity to strengthen elasmobranch management.

77 GHz FMCW Imaging Radar for Low Observable and Small Marine Target Detection in Dynamic Sea Conditions Based on Combined MIMO and DBS

77 GHz FMCW Imaging Radar for Low Observable and Small Marine Target Detection in Dynamic Sea Conditions Based on Combined MIMO and DBS

Effects of small marine energy deployments on oceanographic systems

The placement and operation of marine energy deployments in the ocean have the potential to change flow patterns, decrease wave heights, and/or remove energy from the oceanographic system. Changes in oceanographic systems resulting from harvesting marine energy, particularly tidal and wave energy, may be of concern. These changes include alterations in nearfield and farfield physical processes, as well as potential secondary environmental effects such as changes in sediment transport patterns, biological processes, or coastal erosion. Knowledge of changes in oceanographic systems associated with marine energy is primarily available from numerical modeling studies, informed by some laboratory tests and very few field measurements. A literature review was conducted using the Tethys knowledge base and other online sources, building on conclusions from the Ocean Energy Systems-Environmental State of the Science report. Potential changes in oceanographic systems that may be caused by marine energy differ between tidal and wave devices because of different extraction mechanisms and siting locations. Numerical models show that tidal extraction on the order of hundreds of megawatts or with significant channel blockage is required to create changes in oceanographic processes that exceed natural variability. Effects from wave energy extraction in arrays are localized and dependent on array spacing and proximity to the shore. Available evidence supports the conclusion that the risk of significant environmental effects from such changes could be retired (i.e., less investigation required for every project) for small deployments—those representative of the state of the industry in 2021. Determining changes in oceanographic systems to be low risk for small deployments can thereby streamline environmental consenting by reducing monitoring needs at this early stage in the industry.

Transcription of biochemical defenses by the harmful brown tide pelagophyte, Aureococcus anophagefferens, in response to the protozoan grazer, Oxyrrhis marina.

Aureococcus anophagefferens is a small marine pelagophyte that forms recurrent harmful brown tides blooms with adverse ecological and economic impacts. During blooms, A. anophagefferens experiences lower zooplankton grazing mortality than other phytoplankton potentially due to the synthesis of anti-predator compounds including extracellular polysaccharides. This study characterized the transcriptomic response of A. anophagefferens when exposed to the protozooplankton, Oxyrrhis marina, and assessed whether this response involved chemical cues. Transcriptomes were generated from A. anophagefferens populations grown at high (1×106 cells mL-1) and low (5×105 cells mL-1) cell densities incubated directly with O. marina or receiving only filtrate from co-cultures of A. anophagefferens and O. marina to evaluate the role of chemical cues. There were a greater number of genes differentially expressed in response to grazing in the lower concentration of A. anophagefferens compared to the high concentration treatment and in response to direct grazing compared to filtrate. KEGG pathway analysis revealed that direct grazer exposure led to a significant increase in transcripts of genes encoding secondary metabolite production (p < 0.001). There was broad transcriptional evidence indicating the induction of biosynthetic pathways for polyketides and sterols in response to zooplankton grazers, compounds associated with damage to marine organisms. In addition, exposure to O. marina elicited changes in the abundance of transcripts associated with carbohydrate metabolism that could support the formation of an extracellular polysaccharide matrix including genes related to glycoprotein synthesis and carbohydrate transport. Collectively, these findings support the hypothesis that A. anophagefferens can induce biochemical pathways that reduce grazing mortality and support blooms.

Morphological, molecular identification and evaluation of antioxidant activity of seahorses from the Moroccan coasts

Seahorses, part of the small marine teleost fish family Syngnathidae, are increasingly under threat due to habitat degradation and overfishing. Notably used in traditional Chinese medicine, these fish have demonstrated significant pharmacological and cosmetic properties. In Morocco, however, seahorses are minimally exploited. This study aims to explore the biodiversity of Moroccan seahorses, focusing on identifying species from the Atlantic and Mediterranean coasts both morphologically and molecularly, and evaluating their antioxidant activity.The research involved collecting 62 dried seahorses from local fishermen. These specimens were subjected to detailed morphological and molecular identification through the DNA barcoding method, concentrating on the mitochondrial marker Cytochrome Oxidase I (COI) gene. Following DNA extraction and amplification, the sequences were analyzed for species identification and phylogenetic relationships. Additionally, the antioxidant activities of the seahorses were quantified using assays such as ABTS, reducing power, phosphomolybdenum, and β-carotene-linoleic acid.The combined morphological and molecular analyses consistently identified all specimens as Hippocampus hippocampus, and phylogenetic trees suggested a close relation with European and Turkish counterparts. Furthermore, the antioxidant assays revealed significant activity, with the ABTS assay showing an IC50 of 14.571 mg/mL ± 0.334, and the β-carotene-linoleic acid assay showing an IC50 of 1.273 mg/mL ± 0.166. The reducing power and phosphomolybdenum assays recorded EC50 values of 1.868 mg/mL ± 0.033 and 1.156 mg/mL ± 0.112, respectively. These results confirm the high antioxidant potential of Moroccan seahorses, suggesting their therapeutic value and necessitating measures for their biodiversity preservation at a national level.

Analytical modeling and experimental verification of a multi-DOF spherical pendulum electromagnetic energy harvester

Low-frequency vibration energy harvesting is a promising technology for providing floating buoys and small marine robots with sustainable energy from ocean waves. A spherical vibration energy harvester with multiple degrees of freedom has the advantages of good multi-directional adaptability and compact structure. However, its magnetic field distribution in three-dimension space is much more complex due to the combined effect of a series of cylindrical permanent magnets mounted on the surface of a gimbaled pendulum. The traditional finite element method is too time-consuming to perform efficient parameter design and optimization. To solve this problem, this work develops an analytical electromagnetic model for the spherical vibration energy harvester based on Biot-Savart Law. This model can be used to predict spatial magnetic flux distribution and electromotive force for given magnet and coil parameters. The accuracy and computational cost of the analytical model is verified by the comparison with the finite element method. Furthermore, the optimization of electromagnetic parameters is implemented to achieve maximum energy conversion efficiency. Finally, an optimized prototype is fabricated and tested in both laboratory and real sea. The resonant frequency and energy conversion efficiency of the prototype reaches 1.0 Hz and 25.45 %, respectively. It is shown that the experimental results are in good accordance with the analytical results.

Temperature analysis of extra vessel electromagnetic pump cooling for a Micro nuclear reactor with an electric power of 20 MW

Lead bismuth eutectic (LBE) is used as coolant for MicroURANUS, a small marine nuclear power plant, and this coolant is transported in the plant by an electromagnetic pump. Given the considerable heat generated by the electromagnetic pump, the cooling of the pump is essential. This study compared air cooling and water-cooling methods and found that the maximum temperatures during air and water cooling were 640 K and 372 K, respectively. These findings were utilized to design an electromagnetic pump with water-cooling. The maximum temperature of the pump was lower than the boiling point of water; thus, the pump did not require a separate pressurization. Consequently, the resistance problem of the coil and the deformation problem of the material caused by generated heat can be solved through water-cooling.

Marine invertebrates as proxies for early kelp use along the western coast of South America

Coastal societies have lived at the seaward edge of the Atacama Desert since at least 12,000 years ago. Kelp forest ecosystems provide evidence for important subsistence activity along the entire Chilean coast through fishing and gathering. Despite their importance, especially in hyperarid contexts with limited plant abundance, there is scarce evidence of kelp in archaeological contexts, hampering the study of kelp use in the past. In the present study, we use the presence of small marine invertebrates, inhabitants of stipes and holdfasts of macroalgae, as proxies that indicate past kelp presence. We analyze samples of three species of snails (Tegula atra,Tegula tridentata,andDiloma nigerrima) and one limpet (Scurria scurra) from nine archaeological sites dated between 7,000 and 500 cal years before present located around the area of Taltal (25°Lat S). Modern samples of these species were collected to reconstruct the size of fragmented archaeological shells and subsequently estimate the size of harvested kelps. Through this approach, we estimated the size and relative abundance of kelp used by coastal groups that inhabited the southern part of the Atacama Desert for around 6,500 years. Our results are a contribution to the scarce information on the presence and use of kelp in the prehistory of the Americas and contribute to comparative perspectives with other areas of the world where the use of kelp by humans in the past has already been explored.