Underwater Photography Research Articles

Oyster reef habitat depends on environmental conditions and management across large spatial scales

Oyster reefs provide important services to ecosystems and people, with many of these benefits depending on structurally complex reef habitat. Despite the key role of oyster reef habitat, we have yet to understand natural and anthropogenic drivers of subtidal reef habitat over large spatial scales (>200 km). Chesapeake Bay (USA) offers a valuable system to explore how salinity, restoration, and harvest compare in their influence on subtidal oyster reef habitat because of its broad environmental gradient and mosaic of management types. We applied a remote rapid assessment method using underwater photographs to survey oyster reef habitat in 12 tributaries and scored images based on estimates of oyster percent cover and vertical relief. The broad spatial scale (~215 km) of the survey includes reefs that vary in management status and salinity. Bay-wide habitat scores were higher with greater estimated oyster percent cover and vertical relief on unharvested and restored reefs. Salinity also contributed to Chesapeake Bay-wide patterns, but the relationship depended on harvest status. In assessing the separate management jurisdictions, scores were higher on restored reefs in Maryland and on anthropogenic (i.e. artificially supplemented) reefs in Virginia. A time series over 4 yr in 2 Maryland tributaries showed high and persistent habitat scores in restored sanctuaries, but habitat scores increased for all reefs over time. The results highlight the combined roles of the natural environment and management decisions on oyster reef habitat. The effect of harvest and restoration on habitat underscores the importance of local management decisions in determining the future status of oyster reefs.

Impact of Ship Grounding on Coral Reefs in Indonesian Waters

Indonesia as an archipelagic country is prone to damage to coral reefs. The grounding of ships on coral reefs has resulted in severe physical and biological damage. The grounding of ships on coral reefs has resulted in severe physical and biological damage, including the uprooting and crashing of coral skeletons, dislodgment and displacement of sediment, and loss of three-dimensional complexity. Most of the damage was devastating. The purpose of this study is to identify levels of damage and impact of shipgrounding to coral reefs in Indonesian waters. The research method in this study uses the Line Intercept Transect (LIT) and underwater photo transect (UPT) to measurement of the level of damage and its impact. The result of this study is profile of coral reefs that were predominantly hit by ships was a patch reef (67%) and and mostly occurred due to human error (78%). This research found some types of damage in the form of a trajectory, mounds, propeller, partials, and dispersals. There has been a very significant change in the bottom substrate of the waters both by large, medium, and small vessels. The average live hard coral cover in affected area from 42.70 ± 5.26%, changing to no live coral, it is mean the mortality of live coral cover reached 100%. And rubble coverage increased from 11.19±6.10% to 61±18.41%. Increasing of rubble is an important concern because it causes acute damage to coral reefs, the same as coral damage caused by fishing bombs and destructive fishing.

Coral recruitment and its relationship to hard coral cover in the Derawan Islands, East Kalimantan

Coral recruitment is the process when coral larvae settle to the substrate and establish themselves as a reef community. The success of coral recruitment is very important for the sustainability of coral reefs in an area, including the Derawan Islands which develop underwater tourism. Observations on coral reef recruitment were carried out in the Derawan Islands. This study aimed to determine the density of coral recruitment, hard coral cover, and the relationship between coral recruitment and hard coral cover. Data were collected using the Underwater Photo Transect method at 11 stations in the Derawan Islands. The results showed that coral recruitment in the Derawan Islands was low, ranging from 1.41 to 3.13 colonies.m−2. Hard coral cover was categorized as “moderate” with an average of 28.04% (+SE=3.63%). The relationship between coral recruitment and hard coral cover occurred for medium-sized juvenile corals (3-6 cm). Their negative relationship was shown by the presence of more medium-sized juvenile corals in areas with lower hard coral cover. The large availability of stable substrates such as DCA in areas with low hard coral cover can increase the potential for coral reef ecosystems to recover naturally.

The condition of megabenthos and reef fish in coral reef ecosystems in Aru Islands National Conservation Area, Southeast Maluku, Indonesia

The waters of the Aru Islands are part of the National Marine Protected Areas (MNR), and have extensive coral reefs with high biodiversity. The study was conducted in October 2016 at twelve stations to determine the status of coral cover, composition, and density of megabenthos and reef fishes. Coral reef data collection refers to the Underwater Photo Transect (UPT), and data processing uses Coral Point Count for Excel (CPCe). The Benthos Belt Transect (BBT) method was used for megabenthos data, and the Underwater Visual Census (UVC) method was used for reef fish observations.The result of the benthic component analysis showed that the proportion of live corals at each station ranged from 10.60% to 54.27%, with an average cover value of 31.21%, which fell into the “fairly good” category. Megabenthos density analysis revealed that Drupella cornus had the highest density value (0.29 individuals/m2) and Holohuria edulis (0.01 individuals/m2) had the lowest density. Analysis of the reef fish community revealed that the indicator fish were 168 individuals from the family Chaetodontidae. The group of herbivore fish recorded 116 individuals from threee families: Acanthuridae, Scaridae, and Siganidae. Acanthurus auranticavus and Acanthurus pyroferus are common species found in the waters of the Aru Islands.

An Adaptive Technique for Underwater Image Enhancement with CNN and Ensemble Classifier

Image Restoration is a significant phase to process images for their enhancement. Underwater photographs are subject to quality issues such as blurry photos, poor contrast, uneven lighting, etc. Image processing is crucial in the processing of these degraded images. This research introduced an ensemble-based classifier based on the bagging approach to enhance UW images. The support vector machine and random forest classifiers serve as the ensemble classifier's main classifiers. Additionally, to complement the feature optimization technique, the proposed ensemble classifier leverages particle swarm optimization. The feature selection method for the classifier is improved by the feature optimization process. To validate results, underwater images are collected by the Kaggle repository. In this process, Extreme Learning (EL) and Convolution Neural Network (CNN) are compared with suggested algorithms. The simulation results indicate that the proposed algorithm outperformed the existing work.

Conservation or Degradation? Assessing The Behavior of Underwater Photographers In Italian Marine Protected Areas

Underwater photography is increasing in popularity. It can have positive effects such as conservation awareness and citizen science. Often, however, photographers neglect good environmental practices and engage in potentially damaging behaviors to the marine environment. The management of underwater photography is particularly relevant in marine protected areas (MPAs), where uses of the marine environment need to be carefully balanced. This study aimed to assess and compare underwater photographers' and nonphotographers' knowledge of codes of conduct in MPAs, as well as self-reported and observed compliance with these codes of conduct, and perceptions of the health of the marine environment including dive sites. Through direct observations and questionnaires, 84 divers were studied in three Italian MPAs in the summer of 2021. The difference between underwater photographers and nonphotographers was stark, with the former being more likely to violate MPA rules compared to the latter. There was no difference in knowledge of the effects of their behavior on the marine environment between underwater photographers and nonphotographers. Our results can help provide management considerations to reduce the impacts of underwater photography. Awareness campaigns, predive briefings and the promotion of low-impact underwater photography courses can help to limit unsustainable underwater behaviors among underwater photographers. Effective regulation of underwater photography can increase the carrying capacity of dive sites and have positive environmental and economic effects on MPAs and diving destinations.

The Economic Value of Capture Fisheries Service from Coral Reef Ecosystem on Kelapa Dua Island

Coral reefs are critical ecosystems for coastal and marine biota interaction. The coral reef ecosystem on Kelapa Dua, Seribu Islands, is in poor condition with a low live coral cover. This condition decreases fishery productivity, as the coral reef is the habitat and nursery ground for fish and marine biota. The problem in this research is how to increase the percentage of live coral cover on Kelapa Dua Island, so fishermen do not have to fish further to other islands. This study aims to analyze the coral cover percentage and the economic value of the direct use value of capture fisheries services from the coral reef ecosystem on Kelapa Dua Island. The method used in this study to calculate the percentage of coral reef cover is Underwater Photo Transect (UPT) at a depth of 5 meters along 50m at three locations. The method for the capture fisheries data collection is an accidental sampling questionnaire to 30 out of 50 fishermen with a market value approach. The results of this study indicate that the economic valuation of coral capture fisheries services on Kelapa Dua Island per year for fishermen is IDR 394,800,000/US$ 25,165 (1 USD=15,688 IDR) with a coral reef coverage percentage of 12.45%. This value contributes 2.5% of the economic value of capture fisheries services of the coral reef ecosystem in the entire Kepulauan Seribu National Park. This value can be increased by increasing the diversity of types of catch, the biomass of the catch, and the selling price of the catch.

Coral reef health and the distribution of soft coral abundance in Banten Bay

Banten Bay has several islands which also have coral reefs around them. This study was carried out from October 2021-March 2022 at 9 observation points spread across the islands. This study aims to determine the health of coral reefs and the distribution of soft coral abundance in the three islands. Coral reef data was taken through diving at the depth where coral reefs were first discovered at each station, using the Underwater Photo Transect (UPT) method. The observation line transect was stretched parallel to the shoreline for a length of 50 m. The data in the form of photos were taken using a square transect (58 cm x 44 cm) which was placed alternately in each meter. Based on the observation, the presence of soft coral found at Stations 1-8 were 0.21%, 0.99%, 0.70%, 13.89%, 7.61%, 16,80%, 5,78%, and 4,62%, respectively. Fairly large value of abundance was found at Station 4 and Station 6, while small value of abundances was found at Station 1, Station 3 dan Station 2. Based on Decree of Ministry of Environment No. 4 of 2001, the coral reefs around Pulau Panjang are categorized as bad and fair (unhealthy).

First specimen-based Indonesian record of a rare scorpionfish, Scorpaenopsis obtusa (Actinopterygii: Perciformes: Scorpaenidae), from Alor Island

A single specimen of the shortsnout scorpionfish, Scorpaenopsis obtusa Randall et Eschmeyer, 2002 (Scorpaenidae), collected from the south coast of Ampera, Alor Barat Laut, Alor Island, Indonesia, at 5 m depth, represents the first voucher specimen-supported record of the species from Indonesian waters (previous records from Nusa Penida and northern Sulawesi having being based on underwater photographs). At 91.1 mm in standard length, the Alor specimen is the largest recorded individual of the species to date.

Dominance of the scleractinian coral Alveopora japonica in the barren subtidal hard bottom of high-latitude Jeju Island off the south coast of Korea assessed by high-resolution underwater images.

Coastal benthic communities in temperate regions have been influenced by climate change, including increasing sea-surface temperature. Nevertheless, scleractinian coral Alveopora japonica Eguchi, 1968, is thriving in shallow subtidal hard bottoms around Jeju Island, off the southern coast of Korea. The presence of this corals has negatively impacted subtidal kelp populations in Jeju Island. However, there is no study to document how the presence or absence of this coral relates to other benthic communities. This study investigated the benthos in three shallow subtidal sites (Shinheung (SH), Bukchon (BC), and Seongsan (SS)) in northern Jeju using underwater photography. Macro-benthic organisms appearing on a 1 × 20 m line transect installed at depths of 5, 10, and 15 m at each site were analyzed. Results showed that of the three sites investigated, A. japonica colonies were most abundant at BC, accounting for 45.9% and 72.8% of the total transect area at 10 m and 15 m, respectively. At SS, A. japonica occupied 15.3% of the total area at 15 m and less than 1% at 5 m and 10 m. The same at SH accounted for 10% of the total area at 5 m, and less than 1% at 10 m and 15 m. Dead and bleached colonies accounted for 1.2-11.5% and 1.8-5.7%, respectively, at 5, 10, and 15 m at three sites. At SS, canopy-forming brown algae Ecklonia cava and Sargassum spp. accounted for 20.2 and 24.3% of the total transect area, respectively, at 5 m depth. In contrast, the percent cover of E. cava and Sargassum spp. at SH and BC ranged from 0.1 to 1.8%, respectively. Moreover, non-geniculate coralline algae dominated the subtidal substrate at SH, ranging between 60.2 and 69% at 15 and 10 m. The low cover of A. japonica in SS (at 5 m) coincided with a high percent cover of canopy-forming brown algae. However, canopy-forming brown algae were rare at all depths at SH and BC and were dominated instead by coralline algae and the scleractinian corals. This study, by utilizing a non-destructive method, provides a baseline qualitative and quantitative information for understanding the site and depth-dependent distribution of A. japonica and algal populations, which is important to understand climate change related changes in benthic communities in Jeju and elsewhere.

Diversity of reef fish species in presence of mangrove habitat in Ternate, North Maluku, Indonesia

Abstract. Utama RS, Renyaan J, Nurdiansah D, Makatipu PC, Suyadi, Hapsari BW, Martha E, Rahayu EMD, Sugiharto A. Akbar N. 2022. Diversity of reef fish species in presence of mangrove habitat in Ternate, North Maluku, Indonesia. Biodiversitas 23: 5184-5193. Research on reef fish has been widely reported, where information about reef fish communities is an important factor for evaluating fisheries management and coral reef management. Mangroves as the nursery, foraging, and growing areas were also important to assure sustainable reef fish fisheries. This paper studies reef fish abundance and diversity in Ternate Waters in the presence of mangrove in coral reef habitats. To determines coral reef condition underwater photo transect was performed while an underwater visual census (UVC) was used to determine the abundance and diversity of reef fishes in Ternate waters between 2017 and 2018. A total of 14 stations were used, with eight stations near the mangroves and six stations that did not contain mangroves. Based on the observation, fish species richness in mangrove absence was higher than in the presence of mangroves, with 68 and 65 species in 2017 and 66 and 62 species in 2018. However, the abundance of reef fish was recorded high in the presence of mangroves than in the absence of mangroves, with 390 and 289 individual differences in 2017 and 2018. Mangroves' complexity affected part of reef fish communities in Ternate water, particularly Lutjanidae, Serranidae, and Scaridae, which might influence the abundance of reef fishes rather than the species richness. In addition, carnivore shows a negative effect in the presence of mangroves, in contrast with herbivores. It is related to mangrove functioning as a temporary shelter when high-pressure presence in their natural habitat (reef) and a place for foraging. Therefore, mangrove management must be a consideration in the coral reef or fisheries management program.

Management strategy for marine tourism in Bunaken National Park North Sulawesi Province

Bunaken National Park is well-known as one of the special interest tourist destinations with diving activities as its main attraction. Bunaken National Park is also famous for its unique underwater landscape in the form of coral reef walls. Some of the marine tourism attractions in Bunaken National Park are diving, snorkeling, underwater photography, Bottom Glass Boat (catamaran), dolphin watching, and dugong watching. In its management, Bunaken Park has several problems, such as the potential for tourist attractions that are not optimal, mass tourism, litter and the illegal capture of protected marine animals. This study aims to obtain a marine tourism management strategy and its priorities. The analysis method used is interpretative structural modeling using experts as data sources. The experts used as data sources are 2 people from academics and 1 person from the former manager of the Bunaken National Park (DPTNB). The strategies obtained are visitor management strategies, environmental quality improvement strategies and community empowerment strategies. To realize this strategy, program implementation is strengthening regulations and permits, Waste Management, Destination development, community empowerment and stakeholder cooperation.

A Review of Methods of Removing Haze from An Image

A literature review aids in comprehending and gaining further information about a certain area of a subject. The presence of haze, fog, smoke, rain, and other harsh weather conditions affects outdoor photos. Images taken in unnatural weather have weak contrast and poor colors. This may make detecting objects in the produced hazy pictures difficult. In computer vision, scenes and images taken in a foggy atmosphere suffer from blurring. This work covers a study of many remove haze algorithms for eliminating haze collected in real-world weather scenarios in order to recover haze-free images rapidly and with improved quality. The contrast, viewing range, and color accuracy have been enhanced. All of these techniques it is used in countless fields. Some of the applications that use this technology outdoor surveillance, object recognition, underwater photography, and so on.

Geotechnical performance of fine tailings in an oil sands pit lake

Syncrude Canada Ltd.’s Base Mine Lake (BML), the first commercial-scale demonstration of an oil sands pit lake, was commissioned in December 2012, following in-pit deposition of fine tailings (FT) between 1995 and 2012. The geotechnical design basis for the FT in BML is that it will consolidate and densify over time, contributing to fines sequestration below the water cap. This paper presents the geotechnical performance of the FT in BML within the context of this geotechnical design basis. The FT has settled from 196.0 to 171.6 Mm3 by 2019, with cumulative settlement varying spatially between 0.3 and 6.7 m. FT settlement is consistent with the expected self-weight consolidation as modeled by finite-strain non-linear consolidation theory, and is reflected as temporal increase in the profiles of solids content and effective stress. Sonar surveying, profile sampling, shear strength, and underwater photography show that the transition of geotechnical properties at the mudline becomes increasingly distinct over time. These observations support the geotechnical design basis for BML and indicate the fines continue to be sequestered below the water cap.

In-situ electro-stimulation enhanced branching but not massive scleractinian coral growth

Calcium carbonate (CaCO3) is the main component of the skeleton of scleractinian corals and is a preferable substrate for attachment and growth. An electro-stimulation method based on the electrolysis of seawater, which generates calcium and magnesium minerals as a crystalline coating over artificial metal structures, was used to boost coral growth during the 1970s. Few studies have attempted to compare survival and growth between electro-stimulated corals and non-electro-stimulated corals in situ. In this study, we used 2D image analysis to quantify the growth of branching and massive corals on electro-stimulated structures. Among four metallic structures that were deployed in Sabang, Aceh, Indonesia, three were electro-stimulated (12 V) and one was used as a control. Two branching corals (Acropora gemmifera and Pocillopora verrucosa) and two massive coral species (Porites murrayensis and Porites lobata) were selected. A total of 256 fragments, comprising 128 fragments derived from two branching species and 128 fragments derived from two massive species, were randomly dispatched to each structure. Underwater photographs were taken at three intervals from August 2019 to December 2020. The results showed that the survival rates (excluding lost fragments) of branching corals under electro-stimulation were approximately 19% higher than massive. However, no significant difference was found between the survival rates of the treatment and control groups for both branching and massive corals. Furthermore, we found that under electro-stimulation, branching corals grew faster than controls but not massive. Our study provides pieces of evidence for the potential use of electrochemical processes in stimulating the growth of branching corals.

Identification of enigmatic Mediterranean fish Gobius ater Bellotti, 1888 (Teleostei: Gobiidae) based on morphology from underwater photographs.

Gobius ater Bellotti, 1888 is the Mediterranean gobiid species whose live appearance has remained unknown the longest since its description. A goby observed in southern France in 2021 is here identified as G. ater based on a diagnosis of morphological characters visible on high-quality underwater photographs. Then, the authors provide the first description of colouration in live G. ater and a species diagnosis based on colouration. This diagnosis allows the authors to validate a previous photographic record, also from France. Reviewing all claims of G. ater, they argue that only seven records are unambiguously valid, including the two photographic records presented here.

A Novel Technique For Enhancing Underwater Visibility Using Non-Local Stretch Directional Gradient

Owing to the many effects of the underwater medium, underwater images are often captured with a hazy quality. These effects are caused by suspended particles in the image forming phase, which cause light absorption and scattering. On account of these pictures with fluctuating levels of dimness and colour variation, traditional algorithms have several disadvantages. Underwater image enhancement’s main goal is to increase the clarity and contrast of underwater photographs in order to solve these issues. Our paper describes a novel technique by combining several algorithms characteristics for achieving the following goals: i) better scattering, (ii) grey world assumption, (iii) non-Local stretch Directional Gradient process. For example, a better scattering model would be better at modelling hazy scenes and overcoming the image illumination dimming effect. Second, for uniform visibility recovery on the captured picture, an appropriate gray world-assumption is used. Finally, the Non-Local stretch and Directional gradient filter work on the edge details and overall dual tone enhancement required for a high-quality picture. Simulation experiments indicate that the proposed methodology produces improved visual effects and has a greater impact on consistency metrics than other methods.

Comparative Study of Point Intercept Transect (PIT) Method and Underwater Photo Transect (UPT) to Calculate Hard Coral Cover Percentage

Highlight ResearchPoint Intercept Transect Method (PIT) and Underwater Photo Transect (UPT) to monitor coral cover was comparedPercentage of hard coral cover was analyzedThe average difference of the percentage of hard coral cover obtained from the PIT and UPT was analyzed AbstractCoral reef ecosystems are vulnerable to damage and extinction. Therefore, it is imperative that, as part of conservation, their conditions are monitored using straight forward or easy-to-use methods. The research was intended to compare the effectiveness of using Point Intercept Transect (PIT) and Underwater Photo Transect (UPT) methods in calculating percent hard coral covers. It was conducted at six sites in Karimunjawa Islands, Indonesia: Cemara Besar, Cemara Kecil, Taka Malang, Tanjung Gelam, Menjangan Besar, and Menjangan Kecil. At each site, photographs of coral reefs were taken in two ranges of depths, shallow (3–6 m) and deep (9–12 m), along the length of the predefined transects (100 m for PIT and 50 m for UPT). In UPT, the photos were taken using a 58 x 44 cm frame. Fifty photo frames were collected then processed using Coral Point Count with Excel extensions (CPCe) 4.1. The results showed that PIT and UPT produced different percentages of hard coral cover at each site, with the most significant difference found in deep waters of Menjangan Besar (45.27%) and the least one in deep waters of Menjangan Kecil (0.08%). Overall, the difference in percent covers was averagely 9.79 percentage points, which is still categorized into small. Both methods have their own advantages and disadvantages. However, UPT is preferable because its results can be reanalyzed, especially the identified coral reef species.

New Data on the Biology of Kildin Cod Gadus morhua kildinensis (Gadidae) from Lake Mogilnoe (Kildin Island, the Barents Sea) Obtained by Echo Sounding and Underwater Photography

The distribution of the Kildin cod Gadus morhua kildinensis in Lake Mogilnoye (Kildin Island, Barents Sea) is assessed based on the results of echo sounding and hydrological surveys, underwater photography and field observations. Underyearlings live in the lower part of the freshened upper layer, younger age groups locate in vicinity of the natural dam in the southeastern part of the lake, adults are distributed along the water area of the lake within the depth range of 4.0–6.4 m (mainly 5.0–5.4 m), characterized by favorable temperature values, water salinity, and oxygen saturation.

Effective Framework of Underwater Image Enhancement

Abstract: Underwater photographs are an excellent resource for learning about marine life and analysing the hydrothermal winds that blow across the seafloor. Low contrast, colour distortion, and poor visual appeal are the main obstacles that an underwater image faces. Light disperses and refracts as it progresses from rarer to denser, resulting in a plethora of complexities. The dispersion of light reduces the colour contrast. Water, in addition to dispersion, modifies subsea images due to the presence of subsea animals. We provide a new method for improving underwater fusion photos that accurately restores images underwater. Because the input and a set of processes, such as white balance, gamma correction, sharpening, and weight map manipulation, result in a single image. This research suggests a novel method for recovering and improving underwater photos. We recommended a light canal in front of the underwater environment as the initial step. A clear channel image was analysed and adjusted, environmental light was approximated, and the transmission image was refined in order to reconstruct underwater photos. The simulation was run using the MATLAB software.