scholarly journals Detection of Stones in Marine Habitats Combining Simultaneous Hydroacoustic Surveys

Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 279 ◽  
Author(s):  
Svenja Papenmeier ◽  
H. Hass
Keyword(s):  
Marine Protected Area ◽  
Benthic Communities ◽  
Sediment Surface ◽  
Sidescan Sonar ◽  
Marine Biodiversity ◽  
Outer Reef ◽  
Single Beam ◽  
Marine Deposits ◽  
Marine Habitats ◽  
High Backscatter

Exposed stones in sandy sublittoral environments are hotspots for marine biodiversity, especially for benthic communities. The detection of single stones is principally possible using sidescan-sonar (SSS) backscatter data. The data resolution has to be high to visualize the acoustic shadows of the stones. Otherwise, stony substrates will not be differentiable from other high backscatter substrates (e.g., gravel). Acquiring adequate sonar data and identifying stones in backscatter images is time consuming because it usually requires visual-manual procedures. To develop a more efficient identification and demarcation procedure of stone fields, sidescan sonar and parametric echo sound data were recorded within the marine protected area of “Sylt Outer Reef” (German Bight, North Sea). The investigated area (~5.900 km2) is characterized by dispersed heterogeneous moraine and marine deposits. Data from parametric sediment echo sounder indicate hyperbolas at the sediment surface in stony areas, which can easily be exported. By combining simultaneous recorded low backscatter data and parametric single beam data, stony grounds were demarcated faster, less complex and reproducible from gravelly substrates indicating similar high backscatter in the SSS data.

scholarly journals Species diversity and status of key marine habitats in Cu Lao Cham Marine Protected Area, Quang Nam province

2021 ◽  
Vol 21 (2) ◽  
pp. 201-213
Author(s):  
Long Nguyen Van ◽  
Tuan Vo Si ◽  
Vu Nguyen Van
Keyword(s):  
Coral Reefs ◽  
Protected Area ◽  
Marine Protected Area ◽  
Good Condition ◽  
Marine Biodiversity ◽  
Rocky Shores ◽  
Seagrass Beds ◽  
Soft Bottom ◽  
Marine Habitats ◽  
Submerged Reefs

In recent years, several studies relating to assessments of marine biodiversity conducted in the Cu Lao Cham Marine Protected Area. However, the data and information from these studies have not been synthesized. This study was based on analyses of data and information from 22 sites of coral reefs, ten sites of rocky shores, five sites of seagrass beds, eight sites of Sargassum beds, and four sites on soft-bottom communities conducted in 1994, 2004, 2008, 2016 and 2017. A total of 976 species belonging to 223 families of 9 common groups (330 species corals, 277 species of fishes, 156 species mollusks, 91 species seaweeds, 71 species of polychaetes, 24 species crustaceans, 22 species of echinoderms and five species of seagrasses) were found. Coral reefs supported the highest number of species (779 species) compared to that of the soft- bottom (135 species), seagrass beds (124 species), and rocky shores (58 species). In general, most of the coral reefs and seagrass beds were not in good condition, with a low mean cover of hard corals (24,8 ± 15,7%) and of seagrasses (11,9 ± 11,6%). Densities of target macro-invertebrates and fishes with large sizes and high value were extremely low, giving exception of a high density of large fishes of fusiliers, snappers, emperors, rabbitfishes, queenfishes, barracuda) found at Bai Dau Tai, Bai Bac, Hon Mo, Hon Tai and the submerged reefs (Ran La, Ran Manh).

scholarly journals Protecting the North Sea: New research for biodiversity recovery.

2020 ◽  
Author(s):  
Oceana ◽  
Helena Álvarez ◽  
Allison L. Perry ◽  
Jorge Blanco ◽  
Silvia Garcia ◽  
...  
Keyword(s):  
North Sea ◽  
Marine Biodiversity ◽  
Legal Requirements ◽  
Marine Life ◽  
The North ◽  
Marine Habitats ◽  
Wide Range ◽  
The Face ◽  
The North Sea ◽  
New Research

To help fill gaps in knowledge about marine biodiversity in the North Sea, Oceana carried out two eight week research expeditions, in 2016 and 2017. Oceana’s surveys documented a wide range of habitats and species that are considered priorities for conservation, under national, EU, and international frameworks that recognise them as threatened and/or establish legal requirements for their protection.Oceana’s research has underscored the fact that much remains to be discovered about marine life on the seabed of the North Sea. Continued research is critical for informing efforts to recover biodiversity, an urgent priority in the face of the multiple, intense pressures facing the North Sea’s marine habitats and species.

scholarly journals Development of marine landscape maps for the Baltic Sea and the Kattegat using geophysical and hydrographical parameters

2007 ◽  
Vol 13 ◽  
pp. 61-64 ◽  
Author(s):  
Zyad K. Al-Hamdani ◽  
Johnny Reker ◽  
Jørgen O. Leth ◽  
Anu Reijonen ◽  
Aarno T. Kotilainen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Marine Environment ◽  
Leisure Activities ◽  
Biological Information ◽  
Marine Biodiversity ◽  
The European Union ◽  
The Baltic Sea ◽  
Marine Habitats ◽  
The Baltic ◽  
Bothnian Bay

The Baltic Sea is one of the largest brackish water bodies in the world (Segerstråle 1957) with a number of basins varying from almost fresh water in the northern part of the Bothnian Bay via the more brackish conditions in the southern part to the saline waters of the Kattegat. The Baltic Sea is subject to severe environmental degradation caused by commercial and leisure activities, including fisheries, dredging, tourism, coas t a l development and land-based pollution sources. This causes severe pressures on vulnerable marine habitats and natural re- sources, and a tool for aiding marine management is therefore strongly needed. The marine landscape concept presented by Roff &Taylor (2000) is based on the use of available broad-scale geological, physical and hydrographical data to prepare ecologically meaningful maps for areas with little or no biological information. The concept, which was elaborated by Day & Roff (2000) was applied in UK waters (Connor et al. 2006) before it was adopted by the BALANCE project described here. The aim of developing marine landscape maps is to characterise the marine environment of the Baltic Sea region (the Baltic Sea together with the Kattegat) using geophysical and hydrographical parameters. Such maps can be applied, for example, to an assessment of the Baltic-wide network of marine protected areas, and thus provide a sustainable ecosystem-based approach to the protection of the marine environment from human activities, and contribute to the conservation of marine biodiversity. The BALANCE project is based on transnational and cross-sectoral co-operation with participants from nine countries surrounding the Baltic Sea as well as Norway (Fig. 1), and is partially financed by the European Union through the BSR INTERREG IIIB programme.

scholarly journals Importance of outer reef slopes for commercially important fishes: implications for designing a marine protected area in the Philippines

2017 ◽  
Vol 83 (4) ◽  
pp. 523-535 ◽  
Author(s):  
Kentaro Honda ◽  
Wilfredo H. Uy ◽  
Darwin I. Baslot ◽  
Allyn Duvin S. Pantallano ◽  
Masaaki Sato ◽  
...  
Keyword(s):  
Protected Area ◽  
Marine Protected Area ◽  
The Philippines ◽  
Outer Reef ◽  
Commercially Important

scholarly journals Detection of Boulders in Side Scan Sonar Mosaics by a Neural Network

Geosciences ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 159 ◽  
Author(s):  
Peter Feldens ◽  
Alexander Darr ◽  
Agata Feldens ◽  
Franz Tauber
Keyword(s):  
Neural Network ◽  
Training Dataset ◽  
Habitats Directive ◽  
Sidescan Sonar ◽  
Side Scan Sonar ◽  
Shelf Seas ◽  
Expert Analysis ◽  
Human Interpretation ◽  
High Backscatter ◽  
Network Backbone

Boulders provide ecologically important hard grounds in shelf seas, and form protected habitats under the European Habitats Directive. Boulders on the seafloor can usually be recognized in backscatter mosaics due to a characteristic pattern of high backscatter intensity followed by an acoustic shadow. The manual identification of boulders on mosaics is tedious and subjective, and thus could benefit from automation. In this study, we train an object detection framework, RetinaNet, based on a neural network backbone, ResNet, to detect boulders in backscatter mosaics derived from a sidescan-sonar operating at 384 kHz. A training dataset comprising 4617 boulders and 2005 negative examples similar to boulders was used to train RetinaNet. The trained model was applied to a test area located in the Kriegers Flak area (Baltic Sea), and the results compared to mosaic interpretation by expert analysis. Some misclassification of water column noise and boundaries of artificial plough marks occurs, but the results of the trained model are comparable to the human interpretation. While the trained model correctly identified a higher number of boulders, the human interpreter had an advantage at recognizing smaller objects comprising a bounding box of less than 7 × 7 pixels. Almost identical performance between the best model and expert analysis was found when classifying boulder density into three classes (0, 1–5, more than 5) over 10,000 m² areas, with the best performing model reaching an agreement with the human interpretation of 90%.

scholarly journals Unusually variable paleocommunity composition in the oldest metazoan fossil assemblages

Paleobiology ◽  
2019 ◽  
Vol 45 (02) ◽  
pp. 235-245 ◽  
Author(s):  
Seth Finnegan ◽  
James G. Gehling ◽  
Mary L. Droser
Keyword(s):  
Fossil Record ◽  
Benthic Communities ◽  
Benthic Assemblages ◽  
Β Diversity ◽  
Marine Habitats ◽  
Fossil Assemblages ◽  
Early Metazoan ◽  
Insight Into ◽  
Faunal Variability ◽  
Ecological Differences

AbstractRecent excavations of Ediacaran assemblages have revealed striking bed-to-bed variation in diversity–abundance structure, offering potential insight into the ecology and taphonomy of these poorly understood early Metazoan ecosystems. Here we compare faunal variability in Ediacaran assemblages to that of younger benthic assemblages, both fossil and modern. We decompose the diversity of local assemblages into within-collection (α) and among-collection (β) components and show that β diversity in Ediacaran assemblages is unusually high relative to younger assemblages. Average between-bed ecological dissimilarities in the Phanerozoic fossil record are comparable to within-habitat dissimilarities typically observed over meter to kilometer scales in modern benthic marine habitats, but dissimilarities in Ediacaran assemblages are comparable to those typically observed over 10–100 km scales in modern habitats. We suggest that the unusually variable diversity–abundance structure of Ediacaran assemblages is due both to their preservation as near snapshots of benthic communities and to original ecological differences, in particular the paucity of motile taxa and the near lack of predation and infaunalization.

Subtidal assemblages associated with a geotextile reef in south-east Queensland, Australia

2005 ◽  
Vol 56 (2) ◽  
pp. 133 ◽  
Author(s):  
Rhys A. Edwards ◽  
Stephen D. A. Smith
Keyword(s):  
Fish Assemblages ◽  
Benthic Communities ◽  
Artificial Reef ◽  
Demersal Fish ◽  
Diverse Range ◽  
Marine Habitats ◽  
Sessile Invertebrates ◽  
Hard Structures ◽  
Asymmetrical Design ◽  
Natural Reefs

In marine habitats, the use of geotextile materials as a ‘soft-engineering’ solution is increasingly being considered as an alternative to hard structures. However, very little is known about biological assemblages that develop on geotextile structures. This study provides the first ecological comparison of subtidal assemblages between Narrowneck Artificial Reef (NAR), a geotextile reef in south-east Queensland, Australia, and three nearby natural reefs. Benthic community structure, fish assemblages and habitat complexity were compared between reef types using an asymmetrical design. Although natural reefs supported distinct biotic assemblages, as a class, these reefs differed significantly from NAR. The artificial reef was dominated by macroalgae and supported fewer benthic categories, whereas the natural reefs were characterised by a diverse range of sessile invertebrates. Benthic and demersal fish assemblages were less diverse on NAR, but pelagic fish assemblages were similar on both reef types. The substratum of NAR was less complex than that of the natural reefs; this physical variable was correlated with some of the differences in benthic communities and benthic and demersal fish assemblages. It is likely that the key determinants of the biotic patterns observed in this study are interactions between the age of NAR and the physical properties of geotextile substratum.

scholarly journals Uncovering the environmental drivers of short-term temporal dynamics in an epibenthic community from the Western English Channel

2019 ◽  
Vol 99 (7) ◽  
pp. 1467-1479
Author(s):  
Elizabeth Talbot ◽  
Jorn Bruggeman ◽  
Chris Hauton ◽  
Stephen Widdicombe
Keyword(s):  
Time Series Data ◽  
Temporal Dynamics ◽  
Anthropogenic Impacts ◽  
Benthic Communities ◽  
Food Limitation ◽  
Environmental Drivers ◽  
Sediment Surface ◽  
Series Data ◽  
English Channel ◽  
Larval Recruitment

AbstractBenthic communities, critical to the health and function of marine ecosystems, are under increasing pressure from anthropogenic impacts such as pollution, eutrophication and climate change. In order to refine predictions of likely future changes in benthic communities resulting from these impacts, we must first better constrain their responses to natural seasonality in environmental conditions. Epibenthic time series data (July 2008–May 2014) have been collected from Station L4, situated 7.25 nautical miles south of Plymouth in the Western English Channel. These data were analysed to establish patterns in community abundance, wet biomass and composition, and to link any observed patterns to environmental variables. A clear response to the input of organic material from phytoplankton blooms was detected, with sediment surface living deposit feeders showing an immediate increase in abundance, while predators and scavengers responded later, with an increase in biomass. We suggest that this response is a result of two factors. The low organic content of the L4 sediment results in food limitation of the community, and the mild winter/early spring bottom water temperatures allow the benthos to take immediate advantage of bloom sedimentation. An inter-annual change in community composition was also detected, as the community shifted from one dominated by the anomuran Anapagurus laevis to one dominated by the gastropod Turitella communis. This appeared to be related to a period of high larval recruitment for T. communis in 2013/2014, suggesting that changes in the recruitment success of one species can affect the structure of an entire community.

scholarly journals Effect of hypoxia and anoxia on invertebrate behaviour: ecological perspectives from species to community level

2014 ◽  
Vol 11 (6) ◽  
pp. 1491-1518 ◽  
Author(s):  
B. Riedel ◽  
T. Pados ◽  
K. Pretterebner ◽  
L. Schiemer ◽  
A. Steckbauer ◽  
...  
Keyword(s):  
Benthic Macrofauna ◽  
Sediment Surface ◽  
Small Scale ◽  
Marine Biodiversity ◽  
Ecosystem Structure ◽  
Natural Setting ◽  
Sea Anemones ◽  
Ecological Processes ◽  
Individual Organism ◽  
Key Species

Abstract. Coastal hypoxia and anoxia have become a global key stressor to marine ecosystems, with almost 500 dead zones recorded worldwide. By triggering cascading effects from the individual organism to the community- and ecosystem level, oxygen depletions threaten marine biodiversity and can alter ecosystem structure and function. By integrating both physiological function and ecological processes, animal behaviour is ideal for assessing the stress state of benthic macrofauna to low dissolved oxygen. The initial response of organisms can serve as an early warning signal, while the successive behavioural reactions of key species indicate hypoxia levels and help assess community degradation. Here we document the behavioural responses of a representative spectrum of benthic macrofauna in the natural setting in the Northern Adriatic Sea (Mediterranean). We experimentally induced small-scale anoxia with a benthic chamber in 24 m depth to overcome the difficulties in predicting the onset of hypoxia, which often hinders full documentation in the field. The behavioural reactions were documented with a time-lapse camera. Oxygen depletion elicited significant and repeatable changes in general (visibility, locomotion, body movement and posture, location) and species-specific reactions in virtually all organisms (302 individuals from 32 species and 2 species groups). Most atypical (stress) behaviours were associated with specific oxygen thresholds: arm-tipping in the ophiuroid Ophiothrix quinquemaculata, for example, with the onset of mild hypoxia (< 2 mL O2 L−1), the emergence of polychaetes on the sediment surface with moderate hypoxia (< 1 mL O2 L−1), the emergence of the infaunal sea urchin Schizaster canaliferus on the sediment with severe hypoxia (< 0.5 mL O2 L−1) and heavy body rotations in sea anemones with anoxia. Other species changed their activity patterns, for example the circadian rhythm in the hermit crab Paguristes eremita or the bioherm-associated crab Pisidia longimana. Intra- and interspecific reactions were weakened or changed: decapods ceased defensive and territorial behaviour, and predator–prey interactions and relationships shifted. This nuanced scale of resolution is a useful tool to interpret present benthic community status (behaviour) and past mortalities (community composition, e.g. survival of tolerant species). This information on the sensitivity (onset of stress response), tolerance (mortality, survival), and characteristics (i.e. life habit, functional role) of key species also helps predict potential future changes in benthic structure and ecosystem functioning. This integrated approach can transport complex ecological processes to the public and decision-makers and help define specific monitoring, assessment and conservation plans.

scholarly journals Impaired benthic macrofauna function 4 years after sediment capping with activated carbon in the Grenland fjords, Norway

2020 ◽  
Author(s):  
Caroline Raymond ◽  
Göran S Samuelsson ◽  
Stefan Agrenius ◽  
Morten T Schaanning ◽  
Jonas S Gunnarsson
Keyword(s):  
Activated Carbon ◽  
Biological Effects ◽  
Benthic Communities ◽  
Ecosystem Functions ◽  
Sediment Surface ◽  
Sediment Remediation ◽  
Vital Functions ◽  
Southern Norway

AbstractThe sediments in the Grenland fjords in southern Norway are heavily contaminated by large emissions of dioxins and mercury from historic industrial activities. As a possible in situ remediation option, thin-layer sediment surface capping with powdered activated carbon (AC) mixed with clay was applied at two large test sites (10,000 and 40,000 m2) at 30-m and 95-m depths, respectively, in 2009. This paper describes the long-term biological effects of the AC treatment on marine benthic communities up to 4 years after treatment. Our results show that the capping with AC strongly reduced the benthic species diversity, abundance, and biomass by up to 90%. Vital functions in the benthic ecosystem such as particle reworking and bioirrigation of the sediment were also reduced, analyzed by using novel bioturbation and bioirrigation indices (BPc, BIPc, and IPc). Much of the initial effects observed after 1 and 14 months were still present after 49 months, indicating that the effects are long-lasting. These long-lasting negative ecological effects should be carefully considered before decisions are made on sediment remediation with powdered AC, especially in large areas, since important ecosystem functions can be impaired.

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