benthic habitats
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Hydrobiology ◽  
2022 ◽  
Vol 1 (1) ◽  
pp. 76-88
Author(s):  
David E. Bowles ◽  
Leroy J. Kleinsasser

We collected environmental and habitat data for nymphs of 12 dragonfly species (Odonata: Anisoptera) from 91 stream sites throughout eastern Texas, including urban and non-urban locations. Understanding the relationship of dragonflies to habitat structure and other environmental variables is crucial for the purpose of conserving these insects and better using them as predictive tools for water quality assessments, and refining tolerance values. The objectives of this study were to determine the key environmental variables influencing the diversity and distribution of dragonflies in eastern Texas streams, and further determine if differences in those factors could be observed between urban and nonurban sites. We collected samples separately from benthic habitats and woody snag habitats. Significantly fewer sites were observed to have dragonfly species on snag habitat (mean = 1.25) compared to benthic samples (mean = 14.67) (t-test, p = 0.001). The number of dragonfly species collected among non-urban streams (mean = 9.83) was not significantly different than urban streams (mean = 6.08; t-test, p = 0.07). Detrended correspondence analysis of benthic and snag habitat data collected from non-urban and urban locations showed that most of the species are oriented most closely to benthic habitats in non-urban streams. Snag habitat was shown to be poorly ordinated for all of the species. A canonical correspondence analysis of 29 water quality and habitat variables as environmental determinants of dragonfly diversity and distribution showed that distributional relationships among species are complex and often described by multiple environmental factors.


Marine Policy ◽  
2022 ◽  
Vol 135 ◽  
pp. 104850
Author(s):  
A. De la Torriente Diez ◽  
J.M. González-Irusta ◽  
A. Serrano ◽  
R. Aguilar ◽  
F. Sánchez ◽  
...  

2021 ◽  
Vol 14 (1) ◽  
pp. 133
Author(s):  
Alyson Le Quilleuc ◽  
Antoine Collin ◽  
Michael F. Jasinski ◽  
Rodolphe Devillers

Accurate and reliable bathymetric data are needed for a wide diversity of marine research and management applications. Satellite-derived bathymetry represents a time saving method to map large shallow waters of remote regions compared to the current costly in situ measurement techniques. This study aims to create very high-resolution (VHR) bathymetry and habitat mapping in Mayotte island waters (Indian Ocean) by fusing 0.5 m Pleiades-1 passive multispectral imagery and active ICESat-2 LiDAR bathymetry. ICESat-2 georeferenced photons were filtered to remove noise and corrected for water column refraction. The bathymetric point clouds were validated using the French naval hydrographic and oceanographic service Litto3D® dataset and then used to calibrate the multispectral image to produce a digital depth model (DDM). The latter enabled the creation of a digital albedo model used to classify benthic habitats. ICESat-2 provided bathymetry down to 15 m depth with a vertical accuracy of bathymetry estimates reaching 0.89 m. The benthic habitats map produced using the maximum likelihood supervised classification provided an overall accuracy of 96.62%. This study successfully produced a VHR DDM solely from satellite data. Digital models of higher accuracy were further discussed in the light of the recent and near-future launch of higher spectral and spatial resolution satellites.


2021 ◽  
Vol 9 (12) ◽  
pp. 1368
Author(s):  
Eun Ju Kang ◽  
Sukyeon Lee ◽  
Juhyun Kang ◽  
Hanbi Moon ◽  
Il-Nam Kim ◽  
...  

Caulerpa, a (sub) tropical seaweed, is a notorious taxonomic group and an invasive seaweed worldwide. Similar to several species that have been introduced to benthic habitats through aquariums, Caulerpa sertularioides has also been introduced into Korean aquariums, although it is not native to the region. Thus, it is necessary to evaluate the potential of this species for invading domestic macroalgal habitats. Therefore, an indoor mesocosm experiment was conducted to examine the ecophysiological invasion risk of non-native seaweed C. sertularioides under various climate conditions and exposure to three future climate scenarios: acidification (doubled CO2), warming (5 °C increase from ambient temperature), and greenhouse (GR: combination of acidification and warming); additionally, we compared the invasion risk between future and present climates (control: 20 °C and 470 µatm CO2). High CO2 concentrations and increased temperatures positively affected the photosynthesis and growth of C. sertularioides. Photosynthesis and growth were more synergistically increased under GR conditions than under acidification and warming. Consequently, the performance of this potentially invasive species in the native macroalgal Korean habitat will be higher in the future in coastal environments. Therefore, proper management is required to prevent the geographic expansion of C. sertularioides in the Korean coastal ocean.


2021 ◽  
Vol 944 (1) ◽  
pp. 012035
Author(s):  
M Hamidah ◽  
R A Pasaribu ◽  
F A Aditama

Abstract Tidung Island is one of the islands in Kepulauan Seribu, DKI Jakarta, Indonesia. This island has various benthic that live on the coastal areas, and benthic habitat has various functions both ecologically and economically. Nowadays, remote sensing technology is one way to detect benthic habitats in coastal areas. Mapping benthic habitat is essential for sustainable coastal resource management and to predict the distribution of benthic organisms. This study aims to map the benthic habitats using the object-based image analysis (OBIA) and calculate the accuracy of benthic habitat classification results in Tidung Island, Kepulauan Seribu, DKI Jakarta. The field data were collected on June 2021, and the image data used is satellite Sentinel-2 imagery acquired in June 2021. The result shows that the benthic habitat classification was produced in 4 classes: seagrass, rubble, sand, and live coral. The accuracy test result obtained an overall accuracy (OA) of 74.29% at the optimum value of the MRS segmentation scale 15;0,1;0.7 with the SVM algorithm. The results of benthic habitat classification show that the Seagrass class dominates the shallow water area at the research site with an area of 118.77 ha followed by Life Coral 104.809 ha, Sand 43.352 ha, and the smallest area is the Rubble class of 42.28 Ha.


2021 ◽  
Vol 13 (21) ◽  
pp. 4452
Author(s):  
Bisman Nababan ◽  
La Ode Khairum Mastu ◽  
Nurul Hazrina Idris ◽  
James P. Panjaitan

Spatial information on benthic habitats in Wangiwangi island waters, Wakatobi District, Indonesia was very limited in recent years. However, this area is one of the marine tourism destinations and one of the Indonesia’s triangle coral reef regions with a very complex coral reef ecosystem. The drone technology that has rapidly developed in this decade, can be used to map benthic habitats in this area. This study aimed to map shallow-water benthic habitats using drone technology in the region of Wangiwangi island waters, Wakatobi District, Indonesia. The field data were collected using a 50 × 50 cm squared transect of 434 observation points in March–April 2017. The DJI Phantom 3 Pro drone with a spatial resolution of 5.2 × 5.2 cm was used to acquire aerial photographs. Image classifications were processed using object-based image analysis (OBIA) method with contextual editing classification at level 1 (reef level) with 200 segmentation scale and several segmentation scales at level 2 (benthic habitat). For level 2 classification, we found that the best algorithm to map benthic habitat was the support vector machine (SVM) algorithm with a segmentation scale of 50. Based on field observations, we produced 12 and 9 benthic habitat classes. Using the OBIA method with a segmentation value of 50 and the SVM algorithm, we obtained the overall accuracy of 77.4% and 81.1% for 12 and 9 object classes, respectively. This result improved overall accuracy up to 17% in mapping benthic habitats using Sentinel-2 satellite data within the similar region, similar classes, and similar method of classification analyses.


2021 ◽  
Vol 8 ◽  
Author(s):  
Feifei Liu ◽  
Ute Daewel ◽  
Annette Samuelsen ◽  
Sebastian Brune ◽  
Ulrike Hanz ◽  
...  

Predicting the ambient environmental conditions in the coming several years to one decade is of key relevance for elucidating how deep-sea habitats, like for example sponge habitats, in the North Atlantic will evolve under near-future climate change. However, it is still not well known to what extent the deep-sea environmental properties can be predicted in advance. A regional downscaling prediction system is developed to assess the potential predictability of the North Atlantic deep-sea environmental factors. The large-scale climate variability predicted with the coupled Max Planck Institute Earth System Model with low-resolution configuration (MPI-ESM-LR) is dynamically downscaled to the North Atlantic by providing surface and lateral boundary conditions to the regional coupled physical-ecosystem model HYCOM-ECOSMO. Model results of two physical fields (temperature and salinity) and two biogeochemical fields (concentrations of silicate and oxygen) over 21 sponge habitats are taken as an example to assess the ability of the downscaling system to predict the interannual to decadal variations of the environmental properties based on ensembles of retrospective predictions over the period from 1985 to 2014. The ensemble simulations reveal skillful predictions of the environmental conditions several years in advance with distinct regional differences. In areas closely tied to large-scale climate variability and ice dynamics, both the physical and biogeochemical fields can be skillfully predicted more than 4 years ahead, while in areas under strong influence of upper oceans or open boundaries, the predictive skill for both fields is limited to a maximum of 2 years. The simulations suggest higher predictability for the biogeochemical fields than for the physical fields, which can be partly attributed to the longer persistence of the former fields. Predictability is improved by initialization in areas away from the influence of Mediterranean outflow and areas with weak coupling between the upper and deep oceans. Our study highlights the ability of the downscaling regional system to predict the environmental variations at deep-sea benthic habitats on time scales of management relevance. The downscaling system therefore will be an important part of an integrated approach towards the preservation and sustainable exploitation of the North Atlantic benthic habitats.


Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2227
Author(s):  
Andrea Desiderato ◽  
Jan Beermann ◽  
Maria Angelica Haddad ◽  
Luciano Felicio Fernandes

Epibiotic associations can result in co-introductions of non-indigenous species, which may affect ecosystems in several ways. In fouling communities of three estuaries in southern Brazil, a number of amphipods was found to harbour a dense coverage of epibionts. Three different species, the two globally widespread caprellids Caprella equilibra and Paracaprella pusilla, as well as the ischyrocerid Jassa valida, had been colonised by diatoms. Further scanning electron microscope analyses assigned these diatoms to 14 different species that had previously been reported from benthic habitats. This is one of the scarce records of diatoms attached to amphipods. The occurrence of the diatom Amphora helenensis represents the first report for Brazilian waters as well as the second record for the whole SW Atlantic Ocean. As some diatoms were associated with common fouling amphipods, a possible regional spread aided by these crustaceans seems likely. Possible effects of this amphipod-diatom association on the animals and their implications for the underlying ecosystems of this remain to be elucidated.


2021 ◽  
Vol 8 ◽  
Author(s):  
Dominique Pelletier ◽  
David Roos ◽  
Marc Bouchoucha ◽  
Thomas Schohn ◽  
William Roman ◽  
...  

Essential Biodiversity Variables (EBV) related to benthic habitats and high trophic levels such as fish communities must be measured at fine scale but monitored and assessed at spatial scales that are relevant for policy and management actions. Local scales are important for assessing anthropogenic impacts, and conservation-related and fisheries management actions, while reporting on the conservation status of biodiversity to formulate national and international policies requires much broader scales. Measurements must account for the fact that coastal habitats and fish communities are heterogeneously distributed locally and at larger scales. Assessments based on in situ monitoring generally suffer from poor spatial replication and limited geographical coverage, which is challenging for area-wide assessments. Requirements for appropriate monitoring comprise cost-efficient and standardized observation protocols and data formats, spatially scalable and versatile data workflows, data that comply with the FAIR (Findable, Accessible, Interoperable, and Reusable) principles, while minimizing the environmental impact of measurements. This paper describes a standardized workflow based on remote underwater video that aims to assess fishes (at species and community levels) and habitat-related EBVs in coastal areas. This panoramic unbaited video technique was developed in 2007 to survey both fishes and benthic habitats in a cost-efficient manner, and with minimal effect on biodiversity. It can be deployed in areas where low underwater visibility is not a permanent or major limitation. The technique was consolidated and standardized and has been successfully used in varied settings over the last 12 years. We operationalized the EBV workflow by documenting the field protocol, survey design, image post-processing, EBV production and data curation. Applications of the workflow are illustrated here based on some 4,500 observations (fishes and benthic habitats) in the Pacific, Indian and Atlantic Oceans, and Mediterranean Sea. The STAVIRO’s proven track-record of utility and cost-effectiveness indicates that it should be considered by other researchers for future applications.


2021 ◽  
Vol 8 ◽  
Author(s):  
Lily S. R. Tao ◽  
Yanny K. Y. Mak ◽  
Valerie C. M. Ho ◽  
Ronia C.-t. Sham ◽  
Tommy T. Y. Hui ◽  
...  

Trawl fisheries have been shown to cause overfishing and destruction of benthic habitats in the seabed. To mitigate these impacts, a trawling ban has been enforced in Hong Kong waters since December 31, 2012 to rehabilitate the ecosystem and enhance fisheries resources. Previous studies demonstrated that reduced trawling activities would increase the heterogeneity of benthic habitats, thereby enhancing species richness and abundance of benthic fauna and providing more prey resources for predatory fishes. This study aimed to test a hypothesis that the population and trophic dynamics of the Bartail flathead Platycephalus indicus, a heavily fished benthic predatory fish, at inner and outer Tolo Channel of Hong Kong (i.e., EI and EO) improved with increases in their body size, abundance, biomass, trophic niche, and trophic position after the trawl ban. Samples were collected from trawl surveys before and after the trawl ban to compare the pre-ban and post-ban populations of P. indicus from EI and EO. Body size, abundance, and biomass were assessed in 2004, 2013–2014, and 2015–2016, whereas trophic niche and trophic position were analyzed based on stable isotopes of fish samples collected in dry season of 2012, 2015, and 2018. Following the trawl ban, the abundance and biomass of P. indicus increased in EO, with body size increased in EI. Furthermore, as indicated by the results of stable isotope analysis (SIA) on their tissues and prey items, trophic niche, and trophic position of P. indicus increased in EI and EO, respectively. Our study demonstrated that the trawl ban had promoted the recovery of a predatory fish population through restoring size structure and trophic dynamics.


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