Marine soundscape and fish biophony of a Mediterranean marine protected area

Background Marine soundscape is the aggregation of sound sources known as geophony, biophony, and anthrophony. The soundscape analysis, in terms of collection and analysis of acoustic signals, has been proposed as a tool to evaluate the specific features of ecological assemblages and to estimate their acoustic variability over space and time. This study aimed to characterise the Capo Caccia-Isola Piana Marine Protected Area (Italy, Western Mediterranean Sea) soundscape over short temporal (few days) and spatial scales (few km) and to quantify the main anthropogenic and biological components, with a focus on fish biophonies. Methods Within the MPA, three sites were chosen each in a different protection zone (A for the integral protection, B as the partial protection, and C as the general protection). In each site, two underwater autonomous acoustic recorders were deployed in July 2020 at a depth of about 10 m on rocky bottoms. To characterise the contribution of both biophonies and anthrophonies, sea ambient noise (SAN) levels were measured as sound pressure level (SPL dB re: 1 μ Pa-rms) at eight 1/3 octave bands, centred from 125 Hz to 16 kHz, and biological and anthropogenic sounds were noted. Fish sounds were classified and counted following a catalogue of known fish sounds from the Mediterranean Sea based on the acoustic characteristic of sound types. A contemporary fish visual census had been carried out at the test sites. Results SPL were different by site, time (day vs. night), and hour. SPLs bands centred at 125, 250, and 500 Hz were significantly higher in the daytime, due to the high number of boats per minute whose noise dominated the soundscapes. The loudest man-made noise was found in the A zone, followed by the B and the C zone, confirming that MPA current regulations do not provide protection from acoustic pollution. The dominant biological components of the MPA soundscape were the impulsive sounds generated by some invertebrates, snapping shrimps and fish. The vast majority of fish sounds were recorded at the MPA site characterized by the highest sound richness, abundance, and Shannon-Wiener index, coherently with the results of a fish visual census. Moreover, the acoustic monitoring detected a sound associated with a cryptic species (Ophidion spp.) never reported in the study area before, further demonstrating the usefulness of passive acoustic monitoring as a complementary technique to species census. This study provides baseline data to detect future changes of the marine soundscapes and some suggestions to reduce the impact of noise on marine biodiversity.

Environmental DNA (eDNA) reveals endangered narrow sawfish across Indonesian Reefs

Environmental DNA or eDNA is a powerful method to uncover marine organisms in the seawaters. Furthermore, many marine species are difficult to determine in the sea waters because of their rare existence based on the visual census. In this study, we implemented environmental DNA to investigate the presence of the endangered species of narrow sawfish Anoxypristis cuspidata in Indonesia. Four liters of seawater samples were collected at six locations near the coral reefs ecosystem of Indonesia and filtered at 0.45 μm filter paper. DNA was extracted from the filter paper then Polymerase Chain Reaction (PCR) amplification was performed using the cytochrome c oxidase subunit I (COI) primer and analyzed by Next Generation Sequencing (NGS). The findings revealed that narrow sawfish exist in Indonesian waters, and it also simultaneously showed that environmental DNA could detect rare species. The environmental DNA approach to identifying narrow sawfish can provide reliable results and be used as a survey tool to protect endangered threatened and protected (ETP) species.

Citizen Science for Marine Litter Detection and Classification on Unmanned Aerial Vehicle Images

Unmanned aerial vehicles (UAV, aka drones) are being used for mapping macro-litter in the environment. As drone images require a manual processing task for detecting marine litter, it is of interest to evaluate the accuracy of non-expert citizen science operators (CSO) in performing this task. Students from Italian secondary schools (in this work, the CSO) were invited to identify, mark, and classify stranded litter items on a UAV orthophoto collected on an Italian beach. A specific training program and working tools were developed for the aim. The comparison with the standard in situ visual census survey returned a general underestimation (50%) of items. However, marine litter bulk categorisation was fairly in agreement with the in situ survey, especially for sources classification. The concordance level among CSO ranged between 60% and 91%, depending on the item properties considered (type, material, and colour). As the assessment accuracy was in line with previous works developed by experts, remote detection of marine litter on UAV images can be improved through citizen science programs, upon an appropriate training plan and provision of specific tools.

Analisis Kesesuaian Kawasan Perairan untuk Ekowisata Diving di Pulau Soreh Kabupaten Bintan

Tujuan penelitian ini adalah untuk mengetahui potensi ekologis serta analisis kesesuaian dan daya dukung kawasan perairan Pulau Soreh untuk ekowisata diving. Metode penelitian yang digunakan adalah metode survei dengan teknik pengambilan sampel secara purposive sampling yang terdiri dari 2 stasiun. Pengambilan data karang mengunakan metode PIT (Point Intersept Transect), data ikan menggunakan metode UVC (Underwater Visual Census), data kecerahan mengggunakan secchi disc, data kecepatan arus menggunakan botol berisi air dan dikat dengan tali berukuran yang sudah ditentukan, data kedalaman menggunakan bandul atau pemberat dengan tali yang sudah ditentukan ukurannya dan data sosial dengan metode wawancara. Berdasarkan hasil pengamatan potensi tutupan karang hidup sebesar 1–70 %, kecerahan perairan memiliki kecerahan berkisar 47,2-100%, jumlah jenis life form karang sebanyak 1-13 jenis, jenis ikan karang sekitar 4-14 jenis, kecepatan arus sebesar 10,82-13,36 cm/detik, kedalaman terumbu karang sekitar 3,50-10 meter, aksesibilitas sebanyak 1 aspek, dan biota berbahaya sebanyak 1 jenis. Kesesuaian wisata diving di Perairan P. Soreh pada setiap stasiun merupakan kawasan yang sesuai untuk dilakukan pengembangan ekowisata diving. Daya dukung terumbu karang untuk pengembangan ekowisata diving di Perairan P. Soreh pada setiap stasiun sesuai untuk dilakukan pengembangan wisata diving.

Performance of a baited underwater video system vs. the underwater visual census technique in assessing the structure of fish assemblages in a Mediterranean marine protected area

Accurate, rapid and cost-effective fish assemblage monitoring is fundamental for marine protected area (MPA) management as a pivotal tool to verify whether and to what extent MPA conservation objectives have been achieved and to redefine these objectives in the framework of an adaptive management. Recently, there has been a sharp increase in the number of video-based methods to study fish fauna, such as baited remote underwater video (BRUV) systems, that, depending on the objectives of the monitoring, can provide complementary or additional data to the more commonly used underwater visual census (UVC). Even though BRUV systems have been widely used in a wide range of geographic contexts and habitats, their use in the Mediterranean basin is still sporadic and the evaluation of the efficiency of BRUV systems and whether they can be used to complement other techniques needs investigation. Thus, the objective of this study was to assess the performance of a BRUV system in a Mediterranean MPA and to evaluate its effectiveness in assessing the structure of fish assemblages (abundance and species richness) by comparing estimates with those obtained by the UVC technique. The fish fauna were monitored by BRUV and UVC in the Capo Caccia – Isola Piana Marine Protected Area (Sardinia, Italy), in July and October-November 2020, at four sampling sites and two areas, hundreds of meters apart, for each site. Overall, 46 taxa and a total of 3620 individuals were observed by BRUV, while 36 taxa and a total of 2995 individuals were observed by UVC. The species first observed in front of the camera’s field of view and able to reach the maximum abundance were the planktivores (Chromis chromis and Oblada melanura) followed by several carnivorous species belonging to the families Labridae, Serranidae and Sparidae, and lastly two carnivores (Mullus surmuletus and Mugilidae spp.) and some high-level predators (Dentex dentex, Seriola dumerili, Sphyraena viridensis, Dicentrarchus labrax). The maximum species richness and abundance were reached between 39 and 50 min. The cumulative species richness increased until around 30 min. Species richness was higher during the BRUV compared to the UVC monitoring. The consistency in findings between BRUV and UVC and a better performance of BRUV in detecting some species (mainly high-level predators), supports BRUV as an additional technique for describing and quantifying species richness and abundance also in the Mediterranean Sea. Based on the results of this study, the advantages/disadvantages, shortcomings, suggestions and resources needed for the two techniques are outlined.

Seascape Context as a Driver of the Fish Community Structure of Posidonia oceanica Meadows in the Adriatic Sea

Marine underwater habitats dominated by seagrass Posidonia oceanica play an essential role in fish community assembly, affecting taxonomic and functional diversity, abundance and fish behavior. The value of seagrasses as habitat depends on the spatial arrangement of the seascape elements and the availability of alternative habitats. Little is known about the effect of the seascape context of P. oceanica meadows on fish assemblages in the Mediterranean Sea. To identify P. oceanica meadows’ relative importance as a habitat for fishes, fish communities in the Croatian Adriatic Sea were investigated, using SCUBA lure-assisted visual census. The results show a significant effect of different arrangements of P. oceanica meadows’ seascape elements and surrounding habitats on fish community structure. Fragmented mosaic meadows with P. oceanica growing directly on and between rocky-algal reefs/boulders had significantly higher fish abundances compared to both types of continuous meadows (bordering rock and bordering sand). Continuous meadows bordering sand harbored the highest number of unique species. Evidence that alternative structured habitats within proximity to seagrass beds may affect the community structure of associated fish assemblages is provided, highlighting the need to consider P. oceanica meadows’ seascape context in conservation management and experimental design for fish community structure.

Variasi Temporal Kelompok Ikan Terumbu Karang di Pulau Tidung Kecil Menggunakan eDNA Metabarkoding dan Sensus Visual

Coral reef fish are play key role in coral reef ecosystem. The presence of reef fish affected by antrophogenic and natural factors, such seasonal changes. This study aimed to asess the temporal variation of coral reef fish group in Tidung Kecil Island using eDNA metabarcoding and Undewater Visual Census. This research was conducted at December 2019 (West season) and August 2020 (East season). Target group are dominated in west season (64.1%) and east season (59.25%) using eDNA metabarcoding. While, major group fish are the highest relative abundance in both season by using Underwater Visual Census. Family Carangidae are the highest species richness (15 species) in wet season and Serranidae (3 species) in east season, respectively. Futhermore, famili Pomacentridae are the most richness species in west and east seasons 10 and 11 species respectively. Thus, it can be concluded these two methods are effective for monitoring structure or abundance of coral reef fish based on seasonal variation. Ikan karang menjadi indikator dalam menilai keanekaragaman hayati di ekosistem tersebut. Keberadaan ikan di ekosistem terumbu karang dapat dipengaruhi oleh faktor antropogenik dan faktor alam salah satunya perubahan musim. Penelitian ini bertujuan untuk menganalisis kelimpahan kelompok ikan terumbu karang di Pulau Tidung Kecil menggunakan eDNA metabarkoding dan Sensus Visual. Pengambilan data dilakukan pada bulan Desember 2019 (musim barat) dan Agustus 2020 (musim timur). Ikan target mendominasi pada musim barat dan timur dengan persentase sebesar 64.11% dan 59.25%. Sensus visual berhasil mendeteksi ikan mayor dengan persentase tertinggi 62.5% di musim barat dan 82.8% di musim timur. Famili Carangidae merupakan famili dengan jumlah spesies tertinggi di musim barat (15 species) dan Siganidae di musim timur menggunakan eDNA metabarkoding (3 species). Hasil UVC menunjukkan famili Pomcentridae memilki jumlah spesies tertinggi di kedua musim (11 dan 10 spesies) menggundakan sensus visual. Dapat disimpulkan bahwa kedua metode tersebut dapat menjadi pendekatan dalam monitoring struktur atau kelimpahan ikan terumbu karang berdasarkan musim.

Prvi dokumentirani zapis o Tetragonurus cuvieri Risso, 1810. (Perciformes, Stromatoidea) duž kalabrijskih obala (Južna Italija, Središnji Mediteran)

The first record of Tetragonurus cuvieri Risso, 1810 off Calabrian coast (Southern Italy, Central Mediterranean) is reported. The specimen, a male of 361 mm total length, was found at a depth of 7 m during a scientific visual census research activity, in March 2017. The sighting was located off the Tyrrhenian coast of Calabria (Paola: 39.355453N, 16.029192E). The present finding represents the 1st documented record for the Tyrrhenian coast of the Calabria region.

Combining Methods to Better Estimate Total Fish Richness on Temperate Reefs: The Case of a Mediterranean Coralligenous Cliff

Coralligenous habitat is considered as one of the most important special habitat types in the Mediterranean; however, due to its inaccessibility, little is known about it, although it is considered as one of the Mediterranean’s richest habitats in terms of species. Due to a low number of studies, it was presumed that the richness of coralligenous fish assemblages is underestimated using traditional visual census methods which are not applicable to the deep, steep, and vertical slopes of coralligenous cliffs and do not capture exhaustively cryptobenthic species commonly found in this habitat. This paper aims at producing a more complete assessment of fish assemblages on a coralligenous cliff by combining different methods, particularly the deep vertical transect visual census and square with anesthetics method. A total of 76 fish species were recorded on a single coralligenous cliff, supporting the opinion that coralligenous cliffs are important Mediterranean biodiversity hotspots. The analysis of species traits between species recorded by the different methods showed how complementary they are to better describe species compositions. Hence, the result of this study demonstrates that the combined use of methods is essential for a more exhaustive description of the whole fish community structure and for accurate estimates of the abundance and diversity patterns, particularly in complex habitats such as coralligenous cliffs.