Sand Bottom Research Articles

Reefs, sand and reef-like sand: A comparison of the benthic biodiversity of habitats in the Dutch Borkum Reef Grounds

Reefs play an important role in the distribution of species associated with hard substrates and are of value for biodiversity conservation. High densities of the habitat building annelid Lanice conchilega also increase local biodiversity. This study describes the benthic biodiversity of a rocky reef and its surrounding sand bottom with dense L. conchilega beds in the Borkum Reef Grounds, north of the island of Schiermonnikoog in the Dutch North Sea. A side-scan sonar survey revealed distinct seabed areas with high acoustic reflections, indicating the presence of hard substrate on the sandy seafloor. To ground truth the side-scan sonar data and make an inventory of the biodiversity of the observed habitats, a multi-method sampling approach (box corer, SCUBA airlift sampler and visual transects, drop-down camera) was used. This revealed (1) rocky reefs: a combination of gravel, stones and rocks; (2) individual rocks in a sandy environment; (3) sand with dense L. conchilega beds (>1500ind·m−2) and (4) sand bottom habitat. A total of 193 taxa were found with many unique species per habitat. Species richness was significantly higher on sand when compared to the rocky reef (NB-GLM; p=0.006), caused by the presence of dense L. conchilega beds (Poisson GLM; p<0.001). Including dense L. conchilega beds as an additional habitat showed that these held a higher species richness than the rocky reefs (NB-GLM; p=0.002), while sand without dense L. conchilega beds did not (NB-GLM; p=0.14). Since the rocky reefs were present on a sandy bottom, the local biodiversity more than doubled with the presence of rocky reefs. The nMDS plot clearly separated the sand and rocky reef communities and also showed a clustering of dense L. conchilega beds within the sand samples. Each method detected unique species, demonstrating the value of a multi-method approach compared to e.g. box coring alone. This study identified several species previously unknown to the Borkum Reefs Grounds area. The total area of rocky reefs in the southern part of the Dutch Borkum Reef area is estimated to be 9.8km2 and of L. conchilega beds with densities >1500ind·m−2 to be 74km2. Further research should focus on the possible function of L. conchilega as an ecosystem engineer creating intermediate sand-reef systems. For mapping these L. conchilega beds, we advise using side-scan sonar imaging combined with ground truthing by drop-down cameras.

Capture, adaptation and artificial control of reproduction of Lophiosilurus alexandri: A carnivorous freshwater species

The present study describes the capture adaptation and reproduction of wild Lophiosilurus alexandri broodstock in laboratory conditions. There were two periods when capturing was performed in natural habitats. The animals were placed in four tanks of 5m3 with water temperatures at 28°C with two tanks having sand bottoms. Thirty days after the temperature increased (during the winter) the first spawning occurred naturally, but only in tanks with sand on the bottom. During the breeding season, there were 24 spawning bouts with egg mass collections occurring as a result of the spawning bouts that occurred in the tanks. The hatching rates for eggs varied from 0% to 95%. The spawning bouts were mainly at night and on weekends. In the second reproductive period, the animals were sexed by cannulation and distributed in four tanks with all animals being maintained in tanks with sand on the bottom at 28°C. During this phase, there were 36 spawning bouts. Findings in the present study contribute to the understanding of the reproductive biology of this endangered species during captivity.

Long-term effects of an offshore wind farm in the North Sea on fish communities

Long-term effects of the Horns Rev 1 offshore wind farm (OWF) on fish abundance, diversity and spatial distribution were studied. This OWF is situated on the Horns Reef sand bank in the North Sea. Surveys were conducted in September 2001, before the OWF was established in 2002, and again in September 2009, 7 yr post-establishment. The sampling surveys used a multi- mesh-size gillnet. The 3 most abundant species in the surveys were whiting Merlangius merlan- gus, dab Limanda limanda and sandeels Ammodytidae spp. Overall fish abundance increased slightly in the area where the OWF was established but declined in the control area 6 km away. None of the key fish species or functional fish groups showed signs of negative long-term effects due to the OWF. Whiting and the fish group associated with rocky habitats showed different dis- tributions relative to the distance to the artificial reef structures introduced by the turbines. Rocky habitat fishes were most abundant close to the turbines while whiting was most abundant away from them. Species diversity was significantly higher close to the turbines. Overall, these results indicate that the artificial reef structures were large enough to attract fish species with a prefer- ence for rocky habitats, but not large enough to have adverse negative effects on species inhabit- ing the original sand bottom between the turbines.

연안 해저 피복 분류를 위한 항공 초분광영상의 수심보정

Remote sensing data is used to increasing efficiency on benthic cover type survey. Satellite and aerial imagery has variance of reflectance by water column effect even if bottom is consisted with same cover type and condition. This study tried to analyze advances of surveying extent and accuracy through water column correction of CASI-1500 hyperspectral image. Study area is coast of Gangneung city, South Korea where benthic environment is rapidly changing with bleaching of coral reef. Water column correction coefficient was estimated using regression models between water reflectance ( ) and depth for sand bottom then the coefficients were applied to whole image. The results shows that expanded interpretable depth from 6-7m to 15m and decreased variation of reflectance by depth. Additionally, water column corrected reflectance image shows 13%p increased accuracy on benthic cover type classification.

Effects of Rearing Density on Growth of the Polychaete Rockworm Marphysa sanguinea

Effects of rearing density on growth and survival of the polychaete rockworm Marphysa sanguinea have been investigated in order to develop rearing techniques for this species. This study was examined over a nine-month period in the Fisheries Science and Technology Center of Pukyong National University. Three rockworm densities, 500, 1,000 and 2,000 worms∙m -2 with weight ranges of < 0.5 g, 0.6-1.5 g, and 1.6-2.5 g, and the no feed control treatment, were stocked in triplicate 0.10 m 2 boxes with sand bottoms. Growth rates were checked with 15 randomly sampled rockworms from each box at months 3, 6 and 9. Results showed that SGRs in all treatments were higher during the first period (0-3 months) than the second (3-6 months) and third periods (6-9 months) for all treatment densities, while SGRs decreased with increasing density. However, survival and growth of worms at high density was not better than low density, but daily biomass production in medium and high density groups was 6.28 g m -2 day -1 for the rockworms of 0.6-1.5 g with 2,000 inds∙m -2 , and 12.6 g m -2 day -1 for group between 1.6-2.5 g with 2,000 inds∙m -2 , and 14.7 g m -2 day -1 for the group of individuals <0.5 g with 1,000 inds∙m -2 . Results showed that M. sanguinea can be one of the most suitable species to commercially exploit in a farming system. In particular, specified densities permit elevated pure production.

Natural recovery and restoration of acidified shallow soft-water lakes: Successes and bottlenecks revealed by assessing life-history strategies of chironomid larvae

Acidification has led to a strong decline of species characteristic of shallow soft-water lakes. In spite of reductions in acidifying deposition, natural recovery of biodiversity is modest or even absent, suggesting that the impact of acidification is difficult to reverse. We compared recovery from acidification in non-restored and restored lakes using data from 1983 and 2004. In restored lakes, accumulated organic matter was removed and alkaline water was supplied, resulting in an increase in pH and alkalinity and a decrease in ammonium, sulphur and aluminium. For evaluation of biotic changes we selected chironomid larvae (Diptera). In restored lakes, rarefied species richness increased, chironomid species composition changed and responses of chironomid taxa and their life-history strategies indicated a shift towards pre-acidification assemblages. Species adapted to dynamic and stressful environments decreased in favour of those with life history strategies suitable for more benign environments. In non-restored lakes, chironomid response did not indicate a recovery, despite an improved water chemistry in terms of decreased acidity and sulphur (not ammonium and aluminium). Instead, stressful conditions related to oxygen shortage became more prevalent as a decrease was observed in the chironomids least adapted to periods with low oxygen availability. Acidification has inhibited decomposition, resulting in the accumulation of organic material. Natural recovery from acidification resumed and increased the decomposition of this accumulated organic material, resulting in release of nutrients, consumption of oxygen and a decline of sensitive bottom-dwelling fauna such as chironomids. Therefore, active restoration by removal of accumulated organic matter from sand bottoms is essential for a recovery of chironomid assemblages.

Descriptive and illustrated diagnosis of Ophiuroidea fauna (Echinodermata) in the shallow waters of North-eastern Brazil

In this study, we present descriptions, illustrations, comments, and bathymetric and geographic distributions of the brittle star species related to the estuary region of Camamu Bay, located in the State of Bahia, Brazil. The brittle star fauna lives on biological substrates, sand bottoms, mud and rubble in the Camamu Bay and comprises 12 species divided into five families. Almost all of them are common in the tropical and subtropical fauna of the regions of shallow water.Ophiophragmus filograneusis reported for the first time in Bahia, and nine other species are recorded for the first time in Camamu Bay:Amphipholis januarii, Amphipholis squamata, Ophiophragmus filograneus, Ophiostigma isocanthum,Ophioderma cinerea, Ophioderma januarii, Ophiactis lymani, Ophiactis savignyi andOphiocoma echinata.The results suggest that the ophiuroid assemblages are strongly affected by marine currents as well as by different kinds of bottom substrate.

Ecology and conservation of dusky grouper (Epinephelidae) in southern Brazil

Event Abstract Back to Event Ecology and conservation of dusky grouper (Epinephelidae) in southern Brazil Mario V. Condini1*, João P. Vieira1, Henrique Cabral2 and Alexandre M. Garcia1 1 Federal University of Rio Grande, Institute of Oceanography, Brazil 2 Universidade de Lisboa, Faculdade de Ciências, Portugal The dusky grouper Epinephelus marginatus has a broad global distribution and is currently listed as an endangered species at the IUCN Red List. This species has large commercial and ecological importance, but only at the last decade the first studies were carried out on its bioecology at its southernmost distribution limit in Southwestern Atlantic. This region is largely formed by sand bottoms, where the occurrence of reefs and rocks are scarce. Rocky bottoms occur in the neritic region (along 20 to 30 m isobaths) and in the jetties in the littoral region, and in both areas the dusky grouper occur frequently. Our studies showed that immature individuals (mean: 4 yrs) of dusky groupers inhabiting rocky jetties in the littoral region represents an important economical incoming for artisanal fishermen, whereas adults (mean: 8 yrs) are mostly caught at offshore banks 15-25 m deep by coastal fisheries. Microscopic analyses of gonads of littoral and neritic individuals suggest that the littoral region is a growing nursery area and the neritic is a reproductive site. Feeding ecology studies based on stomach content and stable isotopes showed that the species has an important role as top predators in both regions. Future studies on the residence time of immature individuals in the littoral using telemetry are fundamental to further understand the ecology of this endangered species in the Southwestern Atlantic and to help its fishing management and conservation. Acknowledgements This study received financial support from the CAPES-Brasil (PVE NºA101/2013) and Fundação O Boticário de Proteção a Natureza (0962_20122). MVC and AMG acknowledge fellowship support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq: 140570/2013-6 and 305888/2012-9, respectively). Keywords: Epinephelidae, conservation, IUCN Red list, Endangered Species, Brazil Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Poster Presentation Topic: Ecology, Conservation and Invasive Species Citation: Condini MV, Vieira JP, Cabral H and Garcia AM (2015). Ecology and conservation of dusky grouper (Epinephelidae) in southern Brazil. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.FMARS.2015.03.00196 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Nov 2015; Published Online: 02 Dec 2015. * Correspondence: Mr. Mario V Condini, Federal University of Rio Grande, Institute of Oceanography, Rio Grande, Rio Grande do Sul, 96203-900, Brazil, mvcondini@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Mario V Condini João P Vieira Henrique Cabral Alexandre M Garcia Google Mario V Condini João P Vieira Henrique Cabral Alexandre M Garcia Google Scholar Mario V Condini João P Vieira Henrique Cabral Alexandre M Garcia PubMed Mario V Condini João P Vieira Henrique Cabral Alexandre M Garcia Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

First record of three Bivalvia species: Thyasira succisa, Lyonsia norwegica and Poromya granulata in the Adriatic Sea (Central Mediterranean)

Three species of bivalves,Thyasira succisa,Lyonsia norwegicaandPoromya granulate, were recorded for the first time in the Adriatic Sea during surveys conducted from 2010 to 2012 on offshore relict sand bottoms at a depth range of 45–80 m.

1P6-2 Bottom sand waves influence on low-frequency propagation in shallow water environment

1P6-2 Bottom sand waves influence on low-frequency propagation in shallow water environment

Reverberation models as an aid to interpret data and extract environmental information

Reverberation measurements obtained with towed arrays are a valuable tool to extract information about the ocean environment. Preston pioneered the use of polar plots to display reverberation and superimpose the beam time series on bathymetry maps. As part of Rapid Environmental Assessment (REA) exercises Ellis and Preston [J. Marine Syst. 78, S359–S371, S372–S381] have used directional reverberation measurements to detect uncharted bottom features, and to extract environmental information using model-data comparisons. One enthusiast declared “This is like doing 100 simultaneous transmission loss runs and having the results available immediately.” Though that was clearly an exaggeration and the results are not precise, the approach provides valuable information to direct more accurate and detailed surveys. The early work used range-independent (flat bottom) models for the model-data comparisons, while current work includes a range-dependent model based on adiabatic normal modes. A model has been developed which calculates reverberation from range-dependent bottom bathymetry, echoes from targets and discrete clutter objects, then outputs beam time series directly comparable with measured ones. Recent work has identified interesting effects in sea bottom sand dunes in the TREX experiments. This paper will provide an overview of the earlier work, and examples from the recent TREX experiment.

Effects of time and duration of rearing with bottom sand on the occurrence and expansion of staining-type hypermelanosis in the Japanese flounder Paralichthys olivaceus

We previously reported that the progression of staining-type hypermelanosis spontaneously ceased at a specific time and area in Japanese flounder Paralichthys olivaceus. To examine whether time is a limiting factor in the spontaneous cessation of staining, we experimentally controlled the initiation and duration of staining by manipulating the bottom substrate condition in the fish tanks. At 151 days post hatching (DPH; 11 weeks), spontaneous cessation of staining was observed in fish reared in tanks without a sandy substrate. However, staining resumed (or was initiated) in tanks where sand was removed from 11 weeks, indicating a strong but temporary effect of bottom sand and the absence of time limitation in the staining progression by 151 DPH. Extended duration of the inhibitory period of hypermelanosis expansion (9 weeks or more) aided in only a 20 % reduction of the final staining area because of the increased rate of staining expansion. The bottom sandy substrate decreased the visibility of the staining area in individuals, but this was observed only before the completion of the staining expansion. These findings are discussed in relation to possible presence of area limitation of future staining, as well as the fundamental nature of staining.

Correlated evolution between mode of larval development and habitat in muricid gastropods.

Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.

Moluscos asociados al arrecife coralino de Tenacatita, Jalisco, en el Pacífico central mexicano

An analysis of the most common species of mollusks of the coral reef of Tenacatita, Jalisco, in the central Mexican Pacific is presented. The study includes species found both in the reef structure as well as in the surroundings of bottom sand adjacent rocky intertidal zone. The systematic list comprises species of mollusks of the Gastropoda, Bivalvia, Polyplacophora and Cephalopoda classes making a total of 123 different species in 48 families, from which Calyptraeidae, Thaididae, Columbellidae, Conidae, Arcidae, Pteridae, Chamidae and Ischnochitonidae are the most representative. A series of ecological observations on the most conspicuous species and their affinity for the various types of habitat on the coral reef are made. A synthesis of all species that have had a change in nomenclature in the last 40 years is carried out. According to a review of the published literature, we found the species listed here are within their known geographic environment; however, they are new records for the study area. Finally, we carried out a comparative analysis between the species richness of the Tenacatita reef and that recorded in other locations of the Pacific coast with and without the presence of coral reefs.

Bathyal suprabenthic assemblages from the southern margin of the Capbreton Canyon (“Kostarrenkala” area), SE Bay of Biscay

The bathyal suprabenthic fauna of the Kostarrenkala area (Capbreton Canyon, SE Bay of Biscay) was sampled during daytime at eight stations located on a bathymetric transect between 175 and 1000m depth using a multinet suprabenthic sled. Two hundred and five suprabenthic taxa were recorded in this area, mainly amphipods, cumaceans, isopods and mysids. Total abundances ranged from 752 to 2640ind./100m2, showing a decreasing trend with depth. Diversity values (H′) ranged between 3.83 and 5.72, increasing significantly with depth. Multivariate analysis of abundance data discriminated three assemblages according to depth: shelf break (72 sp., 1924ind./100m2), upper slope (93 sp., 1485ind./100m2) and mid slope (135 sp., 857ind./100m2) assemblages. Each assemblage was characterised by a distinct dominant species: the shelf amphipod Westwoodilla caecula at the shelf break, the isopod Munnopsurus atlanticus on muddy sand bottoms of the upper bathyal, and the amphipod Rhachotropis gracilis on mid-slope muddy bottoms below the mud line. Such a structure of bathyal assemblages seems to be generalised for the whole margin of the Bay of Biscay.

Environmental changes in Hunshandake (Otindag) sandy land revealed by optical dating and multi-proxy study of dune sands

A stabilized sand dune from the southern Hunshandake (Otindag) sandy land in northeastern China was studied for reconstructing past environmental changes by optically stimulated luminescence (OSL) dating, magnetic susceptibility and particle size analysis. The OSL dating results indicate that the sandy deposits at the bottom of the section formed at ∼11.8ka ago, corresponding to low magnetic susceptibility and low fractions of fine particles (<63μm). The variations of the two climate proxies suggest that the region was mainly influenced by arid climate. Above the bottom sand layer, there are loamy soils, which formed between ∼6.2 and ∼4.3ka ago. The soils have relatively higher magnetic susceptibility and finer grain size than the bottom sands. The climate of this period was relatively warm and humid, dominated by enhanced summer monsoon. During the late Holocene (from ∼4ka to present), Hunshandake was dominated by semi-humid to arid climate, as indicated by the aeolian sand beds and interbedded weak sandy soils.

A laboratory study of irregular shoaling waves

The present research aims to investigate the dynamics of a single laboratory irregular wave, characterized by a narrow-banded spectrum and developing on a sloping sand bottom, in intermediate waters up to the surf zone. Experiments focused on the wave shoaling region, in order to examine how the wave is affected by breaking induced turbulence offshore the surf zone. A 3D acoustic Doppler velocimeter was used to measure the three wave velocity components, which were all processed to evaluate the time-averaged vertical distributions of orbital velocities, wave and turbulent Reynolds shear stresses and turbulent intensities. The vertical distributions of the phase-averaged velocity components, turbulent kinetic energy and transport of turbulence were also analysed. The adopted phase-averaging technique was applied to each investigated measurement point. Therefore, the crucial element of the study is that all the analysed values derive directly from real measurements and are not approximated by any kind of interpolation. The study confirmed some dynamic behaviour in the shoaling zone already known in the literature, such as the typical cell-type flow pattern of the mean flow and the necessity to evaluate the turbulent kinetic energy with all the three velocity components, when available, which would otherwise be underestimated. Referring to the time-averaged wave and Reynolds shear stresses, a contribution was added to the open debate on their order of magnitude. The measured wave Reynolds shear stresses were also compared with the results of the model by Zou et al. (J Geophys Res 111:C09032, 2006), confirming the behaviour typical of dissipative breaking waves. The analysis of turbulence transport in the shoaling zone revealed that it is seaward directed close to the surface and landward directed close to the bottom. The results presented in the paper can be extended only to other analogous flow conditions.

キャピラリーバリアを利用した盛土式廃棄物処分施設における底部集排水砂層の垂直応力下での排水に関する性能評価

キャピラリーバリアを利用した盛土式廃棄物処分施設における底部集排水砂層の垂直応力下での排水に関する性能評価

Holocene intensification of the East Asian summer monsoon: timing and mechanism

A stabilized sand dune from the southern Hunshandake (Otindag) sandy land in northeastern China was studied for reconstructing past environmental changes by optically stimulated luminescence (OSL) dating, magnetic susceptibility and particle size analysis. The OSL dating results indicate that the sandy deposits at the bottom of the section formed at ∼11.8 ka ago, corresponding to low magnetic susceptibility and low fractions of fine particles (<63 μm). The variations of the two climate proxies suggest that the region was mainly influenced by arid climate. Above the bottom sand layer, there are loamy soils, which formed between ∼6.2 and ∼4.3 ka ago. The soils have relatively higher magnetic susceptibility and finer grain size than the bottom sands. The climate of this period was relatively warm and humid, dominated by enhanced summer monsoon. During the late Holocene (from ∼4 ka to present), Hunshandake was dominated by semi-humid to arid climate, as indicated by the aeolian sand beds and interbedded weak sandy soils.

Frequency response of ordnance replicas across multiple scales

Broad-band, multi-aspect backscatter data obtained using small-scaled and full-scaled replicas of Unexploded Ordnance (UXO) are reported. Data were collected using either linear or circular rail systems. The experiments were performed in: (1) NSWC PCD's small scale test bed (less than 1/16 scaled) which has a simulated bottom, (2) NSWC PCD's Facility 383 9-million gallon fresh water test pool which has a 5-ft sand bottom, and (3) the Gulf of Mexico during GULFEX12 off Panama City, Florida. Data were processed using linear and circular synthetic aperture sonar techniques to generate both images and plots of target strength as functions of frequency and aspect angle. The results from all three experiments are compared to each other and with predictions from Finite-element (FE) analysis. These comparisons are used to assess the utility of alternative methods for generating sonar data from bottom targets of sufficient fidelity to study scattering phenomena and support development of automated target recognition. [Work supported by ONR Code 32 and SERDP.]