Underwater Photography Research Articles

Fast cropping method for proper input size of convolutional neural networks in underwater photography

AbstractThe convolutional neural network (CNN) is widely used in object detection and classification and shows promising results. However, CNN has the limitation of fixed input size. If the input image size of the CNN is different from the image size of the system to which the CNN is applied, additional processes, such as cropping, warping, or padding, are necessary. They take additional time to process these processes, and fast cutting methods are required for systems that require real‐time processing. The purpose of our system to which the CNN model will be applied is to classify fish species in real time, using cameras installed in a shallow stream. Therefore, in this paper, we propose a straightforward real‐time image cropping method for fast cutting to the proper input size of CNN. In the experiments, we evaluate the proposed method using CNNs (AlexNet, Vgg 16, Vgg 9, and GoogLeNet).

Health Status of Coral Reef in Tunda Island, Banten Province, Indonesia

Coral reef is an important underwater ecosystem supporting people’s lives in coastal areas. One of the communities depending on the coral reef ecosystem for its food, livelihood, shoreline protection, and recreation needs is a community in Tunda Island. This research aims to analyze and determine the health status of coral reef in the island using a survey method. It was conducted in July 2018 and July 2019. Underwater photography transects were established at two depth areas of ± 3-4 m (shallow water) and ± 10-11 m (reef slope). Analysis of the results of live coral cover was divided into eight categories of groups based on CPCe output series 4.1. The values of coral reef cover at first depth (± 3-4 m) were 64.86% (east side of the island), 55.76% (north toward east side), and 32.22% (west side). The values of coral reef cover at second depth (± 10-11 m) were 36.36%, 25.00%, and 23.63% on the north toward east, east, and central north sides of the island, respectively. In shallow waters of Tunda Island, the coral reef health is classified as moderate to good, mostly those located on the east and the north toward the east sides. At reef slope, the coral reef health is classified as damaged to poor, particularly those located on the south and the south toward the west sides. The difference in the health values implies that most corals occur in shallow waters while deep corals differ from those near the surface and are not safe from impacts of the activities in the coastal area of Tunda Island.

Conservation value of a subtropical reef in south-eastern Queensland, Australia, highlighted by citizen-science efforts

Subtropical reefs are important habitats for many marine species and for tourism and recreation. Yet, subtropical reefs are understudied, and detailed habitat maps are seldom available. Citizen science can help fill this gap, while fostering community engagement and education. In this study, 44 trained volunteers conducted an ecological assessment of subtropical Flinders Reef using established Reef Check and CoralWatch protocols. In 2017, 10 sites were monitored to provide comprehensive information on reef communities and to estimate potential local drivers of coral community structure. A detailed habitat map was produced by integrating underwater photos, depth measurements, wave-exposure modelling and satellite imagery. Surveys showed that coral cover ranged from 14% to 67%. Site location and wave exposure explained 47% and 16% respectively, of the variability in coral community composition. Butterflyfishes were the most abundant fish group, with few invertebrates being observed during the surveys. Reef impacts were three times lower than on other nearby subtropical reefs. These findings can be used to provide local information to spatial management and Marine Park planning. To increase the conservation benefits and to maintain the health of Flinders Reef, we recommend expanding the current protection zone from 500- to a 1000-m radius.

High-resolution optical remote sensing for coastal benthic habitat mapping: A case study of the Suape Estuarine-Bay, Pernambuco, Brazil

The benefits of high resolution remote sensing techniques and data for the mapping of coastal environments include their ability to capture the spatial variability of the rich and diverse sedimentary landforms and habitats of coastal systems as well as gather and manage different types of data and information using the same platform for multi-scale and multi-layer analysis. This work analyses the efficacy of high resolution satellite imagery for mapping benthic habitat and the seascape characteristics of a coastal lagoon (Suape Bay - 40 km south of Recife, Pernambuco, Brazil) subjected to high anthropogenic impact and exposed to different conditions of tides, suspended sediment regime, and wave dynamics, using different types of processing and classification methods. We analyzed two World View 2 images acquired in 2010 and 2015 in similar tidal conditions and low water turbidity. Preprocessing included the application of radiometric and atmospheric correction, sunglint removal, and land/sea areas masking. To extract the depth information, a Band Ratio and Simple Radiative Transfer Model were employed. The model was corrected and calibrated by using a set of 150 control points collected by echo sounding surveying. A benthic terrain model was developed to identify and map topographic features at broad and fine scales. Supervised Pixel and Object-Based classification methods were applied to visible bands of WV2 and bathymetric data to produce benthic habitat maps of the lagoon area. The analyses were validated by ground truthing based on bottom sediment sampling, underwater photographs, and side scan sonar surveys.

Data On Percentage Coral Reef Cover In Small Islands Bunaken National Park.

This article describes the data on coral reef percent cover small islands (Bunaken Island; Siladen Island; Manado Tua Island; Mantehage Island; Nain Island) in Bunaken National Park, Noth Sulawesi Province, Indonesia. The data of coral percent cover from 20 stations (1000 quadrans), surveys were done by scuba diving along 50 m belt transects established on upper reef slope, mostly with depths ranging from 5 to 10 m. The method Used Underwater Photo Transect (UPT) and Coral Point Count with excel (CPCe) analysis. Percentage of coral cover between 6,27% and 69,20%. Manado Tua Island has a percentage of coral cover 42,02%, Bunaken Island 39,63%, Mantehage Island 29,10%, Siladen Island 27,87%, and Nain Island 25,97%. The average of live coral cover on the five islands is 32.92% with moderate category [2].

Study of Corellation between Coral Reef Cover and Abundance of Reef Fish in Poncan Gadang Island Sibolga City

Poncan Gadang Island used by people for marine tourism, underwater and fisheries activities. These activities make the island’s area as a ship transportation route and feared the condition of the coral reef ecosystem will be damaged. This research aims to find out the condition of coral reef (life coral), the abundance of reef fish and the corellation between those two variables in Poncan Gadang Island. This research was conducted in June 2018 using Underwater Photo Transect (UPT) and Underwater Visual Cencus (UVC) methods. From the results of this research were found 14 species of reef fish that consists of 5 families and 161 individual fish with 23.96 % coral reef lifeform percentage (damaged category). The corellation between coral reef lifeform and abundance of reef fish is 29.5%, which means showing sufficient or moderate corellation.

Providing antifouling properties to fishing nets with encapsulated econea

Aquaculture is usually carried out in cage nets made of textile materials. Fouling organisms settle on the cage nets over time, close the mesh openings, and cause unwanted weight gain. In order to prevent this problem, fishing nets or cages are treated with antifouling paints. Therefore, there is a great need for developing eco-friendly antifouling biocides since negative ecological effects have been proven for the current antifouling biocides and paints. In this study, it was aimed to take advantage of the slow and sustained release of microcapsule technology. For this purpose, econea active agent (an eco-friendly antifouling chemical) was encapsulated with spray-dryer method, carried out capsule optimization studies, and impregnated to the ultra-high-molecular-weight polyethylene fishing nets with two different binders as polyurethane and acrylic. Fishing nets, which transferred microcapsules, were compared with a commercial copper oxide-based dye. Microcapsule-treated and untreated net samples were immersed in a marine ecosystem next to an aquaculture zone for six months in the Aegean Sea. Fouling organisms on nets were observed by taking underwater photographs at periodic intervals. Physical tests (tensile strength, variation in mass) were performed on the nets before and after the treatment with microcapsules. Solidity of the nets and analyses of fouling organisms were examined after the field study. These results show that copper-free eco-friendly antifouling microcapsules are effective against the fouling mechanism. The novel ecofriendly formulation has promising results, and slightly dissolving versions of studied ecofriendly microcapsules could be an alternative for copper-based antifouling biocides.

Coral conditions and reef fish presence in the coral transplantation area on Kapoposang Island, Pangkep Regency, South Sulawesi

Coral reefs are currently suffering from serious degradation due to human activities. In 2015, the condition of coral reefs in Kapoposang Island has been very poor with the live coral cover only 16%. Therefore, the coral reef ecosystem on this island needs to be rehabilitated. This study aims to assess coral cover based on the age of transplantation and examine abundance of reef fish in relation to age of transplant module at Kapoposang Island which is in the Wallacea region. Coral transplant was carried out from 2014 to 2018. The transplanted corals were corals of the genus Acropora. Transplants were carried out at a depth 3 to 4 m. The determination of the transplant module as the reef fish’s observation was based on the age of the transplant module, i.e. 1, 2, 3 and 4 years old. Data collection was carried out using the UVC (Underwater Visual Census) method. Data collection was done by using the UPT (Underwater Photo Transect) method. Photograph data was processed using CPCe (Coral Point Count with Excel extension) software using 30 random points for each frame. The significant relationship between live coral cover and reef fish shows that the coral transplantation was successful. There was linear relation between coral habitat cover and the reef fish. The difference in abundance in each transplant module shows the linier relation between the increase of reef fishes and live coral cover. The live coral cover was higher at the two and three years old of the transplant module. During the study, it was found 13 families and 56 species of reef fish. Planktivorous group was the most dominant of reef fish.

Underwater Photogrammetry Application for Coral Reef Mapping and Monitoring

Underwater 3D reconstruction techniques such as underwater photogrammetry are the latest trend in low cost survey techniques. This article explains how the data acquisition process is up to the process of producing an underwater photo map. Automatic data processing for coral reef objects from the initial data acquisition stage to building 3D models from seabed objects to rendering in virtual reality. In this paper, underwater photogrammetry was applied with SfM (Structure from Motion) algorithm in performing 3D reconstruction of coral reefs that will be produce orthophoto map. Geodetic measurements also performed to the model for control point. The analysis will be divided into t-test and F-test. From the processing, coral reef modeling has obtained the result of a linear error which t-test produce <50% data, both at 95% and at 99 % confidence level. The F-test gain a positive value where the point value used in the linear error test on marker L and K, the value at α = 0.05. The 3D coral reef model in the resulting orthophoto still has weaknesses, for example the color appearance that depends on the level of clarity of the water as well as the camera filter used. However, in 2D display is sufficient and can be an alternative to other methods, for example, the LIT method.

A new model study species: high accuracy of discrimination between individual freckled hawkfish (Paracirrhites forsteri) using natural markings.

Variations between distinct natural markings of freckled hawkfish (Paracirrhites forsteri) could allow in situ identification of individuals from underwater photography. Receiver operating characteristic analysis was used to assess the ability of the Interactive Individual Identification System (I3 S) software to assist in discriminating between images of P. forsteri individuals. This study's results show the high discriminant ability of I3 S to differentiate between unlike individuals and identify images of the same individual. The ability to use automatic computer-aided assistance in the study of this species will enable future research to explore behaviour and movements of individuals in the wild.

Prevention of biofouling on aquaculture nets with eco‐friendly antifouling paint formulation

AbstractAquaculture, which is an important part of food supply, is usually carried out in cage nets made of textile materials. Fouling organisms settle on the cage nets over time, close the mesh openings, and cause unwanted weight gain. In order to prevent fouling, aquaculture nets are generally treated with antifouling paints. In this paper, warp knitted cage nets made from various raw materials were treated with three different antifouling paints. Econea was used as a biocide to prepare an eco‐friendly antifouling paint formulation, and two copper‐based commercial antifouling paints were supplied for comparison. Antifouling paint‐treated and untreated net samples were immersed in a marine ecosystem next to an aquaculture zone for 6 months. Settlement of fouling organisms on nets was observed by taking underwater photographs at periodic intervals. Following the field study, changes in the structure of the nets and antifouling performance of the paints were evaluated considering the results of underwater photographs, biomass growth, variation in mass and strength tests. Colour fastness of the antifouling paints to sea water was also measured to learn about biocide release and surface hydrophobicity. The results show that copper‐free eco‐friendly antifouling paint is just as effective against the fouling mechanism for all types of nets as copper‐based commercial antifouling paints. The novel eco‐friendly formulation has promising results, which provides an alternative for producers when considering the selection of raw materials.

Transmission of Desulfovibrio salexigens DSM2638 Bacteria in Pachyseris involuta-Infection Rate and changes in Coral Morphology at different temperatures

Desulfovibrio salexigens is one of the bacteria that infect corals with black band disease (BBD). These bacteria develop fast and cause damage to corals. Therefore, there is a monitor disease transmissinon, especially BBD, in healthy corals to determine the extent to which pathogens can infect coral tissue and the impact of these bacteria on infected coral populations. This study was conducted at the Marine Station Laboratory on Barrang Lompo Island, South Sulawesi, Indonesia. Bacteria were cultured in the Laboratory of Microbiology, Faculty of Medicine, Hasanuddin University. Corals were acclimatised in controlled containers, followed by transmission tests using aquaria (24 units, 45cmx30 cm x30 cm) filled with 15 litres of sterile seawater. A multifactorial approach was used with treatments comprising different incubation temperature (29⁰C and 31⁰C) and different bacterial concentration in the maintenance media (102, 104, and 106 UNIT), as well as the interaction between the effects of temperature and bacterial concentration. Trial parameters were observed every day at intervals of 5 hours. Changes in the appearance diameter of corals infected with pathogenic bacteria were analysed descriptively using underwater photography (Nikon Collfix P7100 camera) and the corals were measured with callipers (precision 0.1 mm). The study concluded that the infection rate of the bacterium D. salexigens strain DSM 2638 in Pachyseris involuta was higher at 31⁰C-29⁰C. There was no interaction between the effects of temperature and bacterial concentration on the infection rate of infected coral fragments. Bacterial attack was more severe on Pachyseris involuta fragments maintained at 31⁰C than at 29⁰C.

Assessing coral reefs condition for rehabilitation site selection using diver-towed survey in an island of Anambas Islands

To select a rehabilitation area of coral reefs in Pahat Island within Anambas Islands, this study was conducted to asses coral reefs condition using diver-towed or manta tow surveys and underwater photo transects (UPT). The results of the manta tow surveys showed coral cover dominated by hard corals percentage ranged between 11% and 50% (categories 2 and 3) in the western, northern and southern parts of Pahat Island. Distribution of hard coral percentage with more than 50% (Category 4: 51% - 75% and 5: 76% -100%) was observed in the eastern part of Pahat Island. While results from UPT showed the hard coral percentage of 62.5%, 33.67% and 17% in the eastern, western and northern of Pahat Island, respectively. There are similarities in the results of coral reef cover Obtained by the manta tow and UPT methods. Conclusions, this study recommends western Pahat Island as a good alternative for a rehabilitation site as the coral coverage was in poor condition.

Review of heterobranch molluscs fauna in the Boka Kotorska Bay, Montenegro

Heterobranch molluscs fauna in Montenegro has been poorly investigated so far. The aim of the present paper is to improve the knowledge about species diversity of these marine organisms in the Boka Kotorska Bay, specific fjord-like entity in the southern Adriatic Sea. New records of seven heterobranch species were obtained by field surveys in 2017, while three new records were provided by analysing underwater photographs from previous periods. The resulted checklist summarizes the knowledge of the diversity of heterobranchs in the Boka Kotorska Bay from the oldest record in 1967 to the present day and consists of a total of 62 heterobranch species.

Review of the moray eels (Anguilliformes: Muraenidae) of the Red Sea, with description of a new species.

Thirty-eight species of moray eels (Muraenidae) from the Red Sea are reported in an updated review. A species account is provided for each species, along with a full synonymy of all nominal species described from the Red Sea. One species is new to science, G. pharaonis, and two species are new for the Red Sea, Gymnothorax phasmatodes (Smith) and Scuticaria tigrina (Lesson). Gymnothorax pharaonis n. sp. is a common species that has long been misidentified as G. undulatus (Lacepède), although it more closely resembles G. margaritophorus Bleeker, to which it is closely related phylogenetically. It is characterized by the following combination of characters: total vertebrae 123-128; body slender, depth at anus 17-28 in TL; maxillary teeth biserial, dentary and vomerine teeth in a single row; color brown with irregular dendritic pale markings, not interconnected or chain-like, with oblique, conspicuous, parallel streaks posteriorly in dorsal fin. The new record of the distinctive whitish G. phasmatodes is based on an underwater photograph taken at Jeddah, Saudi Arabia. The new record of Scuticaria tigrina is based on a specimen collected from Jeddah, Saudi Arabia, and underwater photographs taken from the northern part of the Red Sea. Based on an integrative taxonomical approach by a combination of morphological and phylogenetic analyses and re-examination of holotype specimens, Gymnothorax cinerascens (Rüppell) is resurrected as a valid species, and it is shown that previous records of G. hepaticus (Rüppell), with which it has previously been synonymized, should refer to G. cinerascens. The true G. hepaticus is redescribed based on examination of the holotype and additional specimens collected during the course of this study. The two species are distinguished by the color of the jaws, the position of the median intermaxillary teeth, and a slight difference in the preanal length. They are also clearly distinct genetically. The Red Sea record of Gymnothorax atolli (Pietschmann) is based on an error, possibly a misidentification of G. griseus (Lacepède). A key to the species of Red Sea moray eels and a phylogenetic tree of presently known lineages of Indo-Pacific moray eels are provided including recently collected Red Sea specimens.

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ON THE COVER: Underwater photo showing luxurious growth of the obligately epizoic red alga Melanothamnus maniticola Woodworth, Frankovich & Freshwater sp. nov. on a West Indian Manatee (Trichechus manatus). This species has developmentally different rhizoids that are unique within Melanothamnus and may be an evolutionary adaptation for anchoring the thalli to manatee epidermis. Photo courtesy of Cathy Beck, USGS.

Trissopathes (Anthozoa: Antipatharia) in the north-east Atlantic, with a description of T. grasshoffi sp. nov.

A new species of antipatharian (black coral) in the genus Trissopathes is described. It is common in the bathyal zone of the north-east Atlantic, including the Bay of Biscay, Celtic Slope and adjacent banks and seamounts. The species is often observed in underwater photographs from untrawled parts of carbonate mounds in the area. Trissopathes grasshoffi sp. nov. can be easily distinguished from its three congeners by having relatively sparse branching, a higher density of primary pinnules, and 3-6 secondary anterolateral pinnules as well as by the shape and size of its spines. The present state of knowledge of Trissopathes is reviewed.

Citizen science yields first records of Hippocampus japapigu and Hippocampus denise (Syngnathidae) from Taiwan: A hotspot for pygmy seahorse diversity.

Relatively very little is known about pygmy seahorses, and even basic information regarding their distributions is largely inconsistent and often based on unofficial reports. However, monitoring marine diversity, particularly for small and cryptic species, such as pygmy seahorses, can be both costly and time consuming. In such cases, the use of citizen science can offer an effective tool for addressing knowledge gaps caused by a lack of biodiversity-related data. Scuba divers and underwater photographers were engaged through social media in order to investigate pygmy seahorse diversity in Taiwan. Using this approach five species of pygmy seahorses were identified, including two new records for Taiwan: Hippocampus denise and Hippocampus japapigu, the latter of which is the first record of the species from outside of Japan. These new records mark Taiwan as one of the world’s pygmy seahorse diversity hotspots, matching that of Japan and Indonesia, as well as demonstrating the value of citizen science for marine biodiversity monitoring, particularly for small cryptic species.

Development and application of a low-cost rapid assessment system for coastal benthic habitats.

Information on community structure and spatial distribution of benthic habitats are important in marine conservation and management. Coral areas, often monitored by trained scuba divers, are of importance for the ecosystem goods and services they provide. The data gathered may, however, be limited due to cost and time constraints. These restrictions and the continuing decline in coral reef health contribute to the need to develop rapid methods to efficiently document the distribution and status of coral reefs. A Rapid Assessment Instrument for Coastal Benthic Habitats (ARAICoBeH) System was developed to enable large-scale but low-cost coastal benthic habitat characterization and mapping without compromising accuracy. Inquiries on community structure and status in coral-dominated areas are also possible with the data collected using the method. The instrument, as well as the data processing and mapping algorithm are described in detail in this paper. A comparative study was conducted between ARAICoBeH and the frequently used underwater photo transect method. Variables compared were percent coral cover, functional group diversity, community structure as well as time and monetary requirements. There were no significant differences in estimates of percent coral cover and diversity of benthic functional groups for majority of sites while estimates of community structure were very similar. ARAICoBeH is cheaper and requires less time to gather the same amount of data as that of the photo transect method. The spatial distribution of coastal benthic habitats and community structure of coral-dominated areas in El Nido, Palawan, Philippines, are included to illustrate the application of the method.

Organically enriched sediments and foraminiferal species from the Açu Reef, indicators of upwelling in NE Brazil?

Shallow and deep-water oceanographic confluence over shelf-edge environments affects the development of benthic habitats. We investigated these oceanographic influences on a narrow (6 km wide) and shallow (25–80 m water depth) outer shelf with warm waters (27–30 °C) through 84 sediment samples, CTD profiles, and underwater photographs. We analysed benthic foraminiferal content, sedimentary facies, carbonates, and organic matter in the inter-reef sediments of the newly discovered Açu Reef in north-eastern Brazil. Univariate and multivariate statistical analyses on biotic (foraminiferal assemblages) and abiotic data (temperature, salinity, sediments, depth) were carried out. The results highlight similarity with the Caribbean-type reef community. Among 45 species, the spatial distribution of living Buccella peruviana is directly associated with organically enriched sediments underlying areas of canyon heads and the terminal portion of shelf valleys, where temperature and salinity vertical gradients depict deflection patterns on the near-bottom seafloor, evidencing an upwelling of colder waters and nutrients between 25 m and the shelf edge. Furthermore, Quinqueloculina patagonica, which predominates inside the shelf valley, and Quinqueloculina lamarckiana, surrounding the reef field, reveal that variations in currents energy in the Açu Reef and the valley morphology constrain the transport and deposition of organic carbonate-enriched sediments. This is consistent with the high abundance and diversity of living foraminifera in the inner reef environment, including both large-sized foraminiferal species and colder water-related foraminiferal species that are autochthonous, supporting “in situ” carbonate production and deposition. Therefore, local upwelling associated with canyon heads on the Brazilian Equatorial shelf might be responsible for maintaining remains of living coral-algal systems on mesophotic outer shelves such as the Açu Reef. Our study also shows that foraminifer-derived upwelling signatures at the sediment-water interface could serve as a potential tool to reconstruct paleoenvironmental and climate changes.