Natural Beds Research Articles

Pre-domestication bottlenecks of the cultivated seaweed Gracilaria chilensis.

Gracilaria chilensis is the main cultivated seaweed in Chile. The low genetic diversity observed in the Chilean populations has been associated with the over-exploitation of natural beds and/or the founder effect that occurred during post-glacial colonization from New Zealand. How these processes have affected its evolutionary trajectory before farming and incipient domestication is poorly understood. In this study, we used 2232 single nucleotide polymorphisms (SNPs) to assess how the species' evolutionary history in New Zealand (its region of origin), the founder effect linked to transoceanic dispersion and colonization of South America, and the recent over-exploitation of natural populations have influenced the genetic architecture of G. chilensis in Chile. The contrasting patterns of genetic diversity and structure observed between the two main islands in New Zealand attest to the important effects of Quaternary glacial cycles on G. chilensis. Approximate Bayesian Computation (ABC) analyses indicated that Chatham Island and South America were colonized independently near the end of the Last Glacial Maximum and emphasized the importance of coastal and oceanic currents during that period. Furthermore, ABC analyses inferred the existence of a recent and strong genetic bottleneck in Chile, matching the period of over-exploitation of the natural beds during the 1970s, followed by rapid demographic expansion linked to active clonal propagation used in farming. Recurrent genetic bottlenecks strongly eroded the genetic diversity of G. chilensis prior to its cultivation, raising important challenges for the management of genetic resources in this incipiently domesticated species.

Erosional Damages on Concave Banks of Directional Arcs in Natural Torrent Bed

Erosional Damages on Concave Banks of Directional Arcs in Natural Torrent Bed

Evaluation of Food Web Structure and Complexity in the Process of Kelp Bed Recovery Using Stable Isotope Analysis

Kelp forests have declined gradually all over the world. Understanding the trophic structure of such a productive and diverse ecosystem is crucial for its restoration and effective management. Few studies, however, have focused on the trophic structure and functional recovery of kelp forests in the process of restoration. This study was conducted in the eastern coast of Korea where kelp bed restoration was in process with the removal of sea urchins. In addition to quantitative measurement for recovery using common community parameters, we investigated how fast the stability of a food web structure could be established in the newly restored kelp beds with an initially barren condition, using stable isotope analysis, in comparison with a nearby natural bed and barren site. At the restored bed, total algal biomass and diversity reached the levels of the natural bed within 1 year. While the δ13C and δ15N values of macroalgae and organic matter were separated isotopically, they were similar among sites, excluding organic matter at the natural bed in 2019. Most consumers showed similar isotopic values among sites, with overlapping range for δ13C of producers. However, some herbivores showed higher δ15N values as predators/omnivores, particularly at barrens, which could be explained by trophic plasticity depending on the macroalgal structure. In the restored bed, for the first year, higher trophic diversity (CR, CD) and lower trophic redundancy (MNND, SDNND) showed non-overlapping >50% CIs among sites. However, this distinctive stage moved toward the natural bed upon entering the second year as trophic diversity decreased and trophic redundancy increased while natural bed overlapped at<50% CIs. The recovery speed in this system was fast (1 year for quantitative perspectives and 2 years for functional completion). After removing the sea urchins, recruitment of macroalgae quickly increased concomitantly with consumer groups, boosting the diversity and trophic structure of the restored bed. The trophic structure of the first year of restoration was not an intermediate stage toward the completion, but a transient over-shooting state. This might have been triggered by the fast introduction of diverse macroalgae to the urchin-free bare rock space, providing an interesting finding needed to be tested in other temperate marine systems.

Hindistan’da Çay Kültürü ve Terakota Bhar Fincanları

Dünya’nın en köklü uygarlıklarına ev sahipliği yapan Hindistan, geçmişin izlerini nesilden nesile devam ettirerek geleneklerini etkili şekilde sürdüren önemli bir kültüre sahiptir. Kültürel miraslarına değer veren ülke, geleneksel çömlekçilik üretimini günümüzde halen devam ettirmektedir. Ülkede geleneksel pişmiş toprak üretimi oldukça eskilere dayanmakta olup, pek çok farklı bölgede yer alan doğal yataklardan çıkarılan killi topraklar; kullanım eşyalarına, zanaata ve sanata dönüşmektedir. En çok kullanılan terakota üretimlerden biri, tek kullanımlık çay fincanları olan Bhar’dır. Günümüzde ülke genelinde çay içmek için pişmiş toprak fincanlar, halk tarafından yoğun talep görmektedir. Köklü çay kültürüne sahip olan ve farklı damak tatlarını içeren Hint çayları; çoğunlukla tercihen geleneksel yöntemlerle çömlekçi tornasında şekillendirilen Bhar’larda içilmektedir. Düşük derecelerde geleneksel fırınlarda pişirilerek kullanıma hazır hale getirilen bu terakota fincanlar, çömlekçiler tarafından günlük üretilmektedir. Bu araştırmada, Hindistan’a özgü çay kültürü ile bu kültür içinde yer alan ve toplum tarafından kanıksanmış terakota Bhar fincanlar incelenmiştir. Bu bağlamda; terakota çay fincanlarının geleneksel üretim yöntemlerine ilişkin süreçleri, Bhar kullanımının kültürel ve geleneksel boyutu, çömlek üreticilerinin sosyo-ekonomik durumu, fincanların tek kullanımlık olması sebebiyle ortaya çıkan çevre faktörü ile ilgili konular ele alınmıştır.

Hydraulic Jump on a Partially Vegetated Bed

AbstractHydraulic jump may form when a supercritical flow runs over a vegetated bottom and change the downstream flow hydraulics and fluid properties after air‐water mixing and energy dissipation at the flow transition. Unlike the abundant literature on hydraulic jump characteristics on engineered or natural sediment rough beds, few studies of vegetation roughness effects have been reported. New experiments were conducted by creating hydraulic jumps with identical inflow Froude numbers on a smooth bed, fully and partly grated rough beds, and partially vegetated grate‐rough beds covered with artificial plants of different densities. The free‐surface dynamics and air‐water flow properties were investigated with primary focus on the interaction between the flow and flexible vegetation barrier/roughness, in addition to the effects of Froude number and inflow roughness conditions. The characteristic jump and jump roller lengths were found shortened as the jump roller was deflected over the vegetation layer. The flow structure modification was observed with a steepening of the roller free‐surface profile and enhanced surface wave propagation, especially when the flow experienced an invert roughness discontinuity at the toe. An increasing bubble detection frequency was obtained in nonvegetated channels when the bed was roughened, but additional vegetation on the rough invert caused reduction in the bubble frequency and cross‐sectional mean air concentration by inducing roller deflection and air bubble detrainment. The results indicated that the effects of perturbing artificial flexible vegetation with relatively large plant height could be different from uniformly distributed rigid bed roughness elements and complicated by the time‐varying flow‐vegetation interaction.

Recent advances in seaweed seedling production: a review of eucheumatoids and other valuable seaweeds

Modern seaweed farming relies heavily on seedlings from natural beds or vegetative cuttings from previous harvests. However, this farming method has some disadvantages, such as physiological variation in the seed stock and decreased genetic variability, which reduces the growth rate, carrageenan yield, and gel strength of the seaweeds. A new method of seedling production that is sustainable, scalable, and produces a large number of high-quality plantlets is needed to support the seaweed farming industry. Recent use of tissue culture and micropropagation techniques in eucheumatoid seaweed production has yielded promising results in increasing seed supply and growing uniform seedlings in large numbers in a shorter time. Several seaweed species have been successfully cultured and regenerated into new plantlets in laboratories using direct regeneration, callus culture, and protoplast culture. The use of biostimulants and plant growth regulators in culture media increases the seedling quality even further. Seedlings produced by micropropagation grew faster and had better biochemical properties than conventionally cultivated seedlings. Before being transferred to a land-based grow-out system or ocean nets for farming, tissue-cultured seedlings were recommended to undergo an acclimatization process to increase their survival rate. Regular monitoring is needed to prevent disease and pest infestations and grazing by herbivorous fish and turtles during the farming process. The current review discusses recent techniques for producing eucheumatoid and other valuable seaweed farming materials, emphasizing the efficiency of micropropagation and the transition from laboratory culture to cultivation in land-based or open-sea grow-out systems to elucidate optimal conditions for sustainable seaweed production.

An experimental study on the anisotropic and intermittent behaviour of a turbulent flow over a rough bed

The flow field in open channels can be classified into different zones according to the velocity distribution. To explore the anisotropic and intermittent behaviour in the turbulent flow layers, an experimental study was performed using Particle Image Velocimetry (PIV) measurements in a hydraulic flume with rough bed. Specifically, the analysis has been focused on the two-dimensional (2D) high-order structure functions applied to the velocity data. It is demonstrated that the system spans from large-scale anisotropy, which is induced by the main shear of the boundary layer, to small-scale isotropy. Moreover, it is shown that the intermittency is more pronounced in the near-bed layer, where the flow is more populated by coherent whirling structures. In essence, both anisotropy and intermittency are proved to be important phenomena for natural bed rivers, since they affect the turbulence transport characteristics of the flow.

Numerical Study on the Shear Stress Characteristics of Open-Channel Flow over Rough Beds

Bed shear stress is an important measure of benthic habitats since it is related to many ecological processes. In this study, we focused on the fluctuating characteristics of shear stress in rough-bed open-channel flows. The roughness element method was adopted to mimic natural rough beds and the Improved Delayed Detached Eddy Simulation (IDDES) model was used to obtain comprehensive information about shear stress near the rough bed. Three arrangement patterns of the roughness elements were simulated to compare their effects on flow structure and shear stresses. The arrangements of the roughness elements altered the Reynold stress and turbulent kinetic energy characteristics, due to the variance of blockage in lateral directions that led to flow detachment and changes in the flow directions. Quadrant analysis revealed the spatial variations of the instantaneous shear stress burst events at different locations in the wake. By using spectrum analysis, the accumulation of shear-stress energy from small to large vortex scales was estimated, which revealed that the instantaneous effect of the shear stress was significantly stronger than the effect of the time-averaged shear stress, especially on small scales. The results of this study suggest the significance of the fluctuation part of shear stress in further studies on ecological processes.

Seaweed Beds and Community Structure in the East and South Coast of Korea

This study conducted a community investigation via scuba-diving excursions into the subtidal regions of seven sea areas on the eastern coasts and three sea areas on the southern coasts, from October to December 2017, to determine the characteristics of seaweed communities and the current status of barren ground in natural seaweed beds in Korea. The results showed that species composition and average biomass in the sea area were 5–48 species and an average of 114.42 g/m2 (0.29–273.60 g/m2) in the eastern coasts, where red algae—an annual opportunity species—were dominant, and 21–48 species and an average of 1056.84 g/m2 (53.03–2683.02 g/m2) in the southern coasts, where perennial large brown algae were dominant. Using Orfanidis’ EEI-c model, evaluations of the community states showed they varied significantly depending on the inclusion of melobesidean algae, and this model was determined to be inappropriate for direct application in sea areas with a low coverage of all macroalgae. A comprehensive review of the seaweed community characteristics of seaweed beds, the marine environment, the coverage of melobesidean algae, and the analysis results regarding the density of grazers showed that a decrease in the seaweed community, according to the barren ground phenomenon, was more severe in the eastern than southern coasts. Furthermore, there were also significant differences in seaweed community characteristics according to sea area and barren ground. Therefore, suitable countermeasures corresponding to the characteristics of each sea area are necessary; for example, the creation of growth substrates for the colonization of macroalgae in Deoksin and Saido Is., the transplantation of large brown algae in Gangyang and Daedurado Is., action plans for marine forest monitoring in Geomundo Is., and an improvement in substrates in Yeongjin, Mangsang, Daejin, Chogok, and Geundeok are possible countermeasures.

Forensic carbon accounting: Assessing the role of seaweeds for carbon sequestration.

Carbon sequestration is defined as the secure storage of carbon-containing molecules for >100 years, and in the context of carbon dioxide removal for climate mitigation, the origin of this CO2 is from the atmosphere. On land, trees globally sequester substantial amounts of carbon in woody biomass, and an analogous role for seaweeds in ocean carbon sequestration has been suggested. The purposeful expansion of natural seaweed beds and aquaculture systems, including into the open ocean (ocean afforestation), has been proposed as a method of increasing carbon sequestration and use in carbon trading and offset schemes. However, to verify whether CO2 fixed by seaweeds through photosynthesis leads to carbon sequestration is extremely complex in the marine environment compared to terrestrial systems, because of the need to jointly consider: the comparatively rapid turnover of seaweed biomass, tracing the fate of carbon via particulate and dissolved organic carbon pathways in dynamic coastal waters, and the key role of atmosphere-ocean CO2 exchange. We propose a Forensic Carbon Accounting approach, in which a thorough analysis of carbon flows between the atmosphere and ocean, and into and out of seaweeds would be undertaken, for assessing the magnitude of CO2 removal and robust attribution of carbon sequestration to seaweeds.

A trishear model with self-adaptive propagation-to-slip ratio

Natural beds at different stratigraphic levels display different degrees of folding. Variable propagation-to-slip ratios in the trishear models are more appropriate for the reproduction of natural folds. An improved trishear model with self-adaptive propagation-to-slip ratio, called TMSP, is proposed in this paper. Transverse isotropy elastic constitutive relationships are utilized to formulate the mechanic behaviors of the overlying sediments. The von Mises failure criterion is introduced to determine whether the material points are destroyed in TMSP. Compared with previous trishear models, TMSP has the advantage that propagation-to-slip ratio can be updated with the proceeding of fault rupture propagation and is not required to be predetermined. A natural fault-propagation fold, Tejerina fold, can be reproduced well by TMSP. Finally, a series of simulations are conducted to investigate the influences of three key parameters of TMSP, including apical angle, yield stress, and elastic modulus, on faulting process and folding growth.

Gonadal cycle, reproductive indices and detection of parasitism in the clam Ameghinomya antiqua in natural beds of importance for fisheries.

The clam Ameghynomia antiqua is a highly important resource for fisheries due to its high catches volume. It is the bivalve mollusc with the highest fisheries landings from natural beds on the Pacific coast of southern South America; however, studies of the reproductive conditions of this species are scarce and date back many years. The object of the present work was to evaluate the reproductive characteristics of the species, analysing its gametogenic and gonadal cycle, and reproductive indices, in fishery locations that present the natural beds with the highest fisheries catches, as well as parasite loads in the species. The gonads of the individuals were sampled monthly over a year and classified into one of three states called: “in development”, “ripe” and “spawned”. Synchrony between the sexes was observed in the indicators of the Gonadosomatic Index and Condition Index in each of the locations, although no synchrony was observed between locations. In the gametogenic cycle, the "ripe" state was observed in females in spring-summer, followed by rapid recovery to new development of the gonads; in males the "ripe" state was observed throughout the year. It was observed that males entered the “spawned” state one month ahead of females. The presence of digenean parasites in the state of metacercariae was detected in the gonads and mantle. No significant differences were found in the prevalence or intensity of infection when analysed by sex and month. The metacercariae were identified, by sequencing of three DNA regions, as belonging to the clade shared by species of the genus Parvatrema and close to the Gymnophalloides; both these genera belong to the family Gymnophallidae of the superclass Digenea. Infection was observed to reduce the gonadal tissue, in some cases causing castration. This is the first record of the presence of these parasites of A. antiqua, with genetic identification at genus level. These results are relevant for act proper management of this resource, which is important for fishing.

Settlement of oyster Magallana bilineata (Röding, 1798) spat in the natural environment: seasonality and substrate texture preference

ABSTRACT This study determined the seasonality of Magallana bilineata spat settlement in a natural oyster bed and established surface texture preference of competent larvae by comparing the numbers of spat settling on the smooth and rough surfaces of ceramic tiles over a period of 31 months. This will guide farmers when to deploy cultches to maximise spat harvest. Regardless of tile orientation, spat numbers were significantly higher on the rough side (129.07 ± 9.3 m−2) than on the smooth side (66.95 ± 7.0 m−2). Spat collection was highest in March, June and July in each of 2015, 2016 and 2017. There was no significant correlation between the number of spat settling in each month with temperature, salinity, pH, dissolved oxygen (DO), sulphide, phosphate, nitrate, nitrite and ammonia concentrations, plankton density measured at deployment and retrieval of tiles, except for DO during deployment. The only significant correlations with mean shell length (SL) were with DO and ammonia during tile retrieval. Mean SL did not significantly differ between tile orientations and surfaces but differed between months, being highest in August 2015 and August 2016. From these results, it is best to deploy roughened cultches in this particular area in March, June and July.

Mapping oysters on the Pacific coast of North America: A coast-wide collaboration to inform enhanced conservation.

To conserve coastal foundation species, it is essential to understand patterns of distribution and abundance and how they change over time. We synthesized oyster distribution data across the west coast of North America to develop conservation strategies for the native Olympia oyster (Ostrea lurida), and to characterize populations of the non-native Pacific oyster (Magallana gigas). We designed a user-friendly portal for data entry into ArcGIS Online and collected oyster records from unpublished data submitted by oyster experts and from the published literature. We used the resulting 2,000+ records to examine spatial and temporal patterns and made an interactive web-based map publicly available. Comparing records from pre-2000 vs. post-2000, we found that O. lurida significantly decreased in abundance and distribution, while M. gigas increased significantly. Currently the distribution and abundance of the two species are fairly similar, despite one species being endemic to this region since the Pleistocene, and the other a new introduction. We mapped the networks of sites occupied by oysters based on estimates of larval dispersal distance, and found that these networks were larger in Canada, Washington, and southern California than in other regions. We recommend restoration to enhance O. lurida, particularly within small networks, and to increase abundance where it declined. We also recommend restoring natural biogenic beds on mudflats and sandflats especially in the southern range, where native oysters are currently found most often on riprap and other anthropogenic structures. This project can serve as a model for collaborative mapping projects that inform conservation strategies for imperiled species or habitats.

Response of Flow and Saltating Particle Characteristics to Bed Roughness and Particle Spatial Density

AbstractWith the goal to explore the effects of natural bed roughness on bedload transport, numerical simulations of flow and particle saltation are carried out with varying bed roughness and particle spatial density. A combination of Eulerian and Lagrangian point‐particle methods is applied to solve the equations of motion of the fluid and the particles within the large‐eddy simulation framework. Flows over smooth and rough beds with four particle densities are considered. As the bed roughness increases, there is a leftward shift of the double‐averaged streamwise velocity profiles against dimensionless vertical distance, which is scaled with the bed roughness height, an upward shift of the peak values of double‐averaged Reynolds stresses, and a fragmentation and disappearance of coherent structures in the form of high‐speed and low‐speed near‐bed streaks. These observations are consistent with those of previous studies. As the bed roughness increases, the mean resting time of saltating particles increases, however the particles' saltation length, velocity, and angular velocity decrease, while their saltation height remains almost unchanged. Saltation height, saltation length, particle angular velocity, and resting time exhibit linear, gamma, normal, and exponential distributions, respectively. Further, as the bed roughness increases, the kurtosis and skewness of some particle parameters vary, and the particle velocity shifts from a symmetrical normal to an asymmetrical gamma distribution.

Spatiotemporal distribution of paralytic shellfish poisoning (PSP) toxins in Beagle Channel (South America) during 2005–2017

Toxigenic algal blooms have been reported since 1886 in the Beagle Channel, at the southern limit of South America, mainly associated with the occurrence of paralytic shellfish poisoning (PSP) toxins produced by dinoflagellates of the genus Alexandrium. Toxic outbreaks have serious impacts on marine wildlife and ecosystem services, particularly on fisheries and mussel aquaculture. Within the framework of the Shellfish Toxicity Monitoring Program carried out close to Almanza in Beagle Channel eastern coastal waters, here we analyzed the spatiotemporal patterns of PSP toxins in the Magellan mussel Aulacomya ater and the blue mussel Mytilus edulis, measured by the mouse bioassay for 12 years, between 2005 and 2017. PSP outbreaks occurred mostly during summer and their duration was significantly longer than for outbreaks detected during spring and winter. A marked interannual variability in their magnitude was also evident. The largest outbreaks were detected in summers 2010–2011, in extreme warm and low-wind conditions, reaching up to 5600 µg saxitoxin equivalent per 100 g of tissue, causing a closure of shellfish fisheries of up to 200 days. Small scale spatial variability in PSP was also found, the highest values being observed in the main mussel culture areas, and the lowest in the natural mussel beds. PSP toxicities for the Magellan mussel were significantly higher than for the blue mussel. Natural detoxification in mussels from Beagle Channel followed an exponential decay, with mean detoxification rates of 3.5% toxin day−1, lower than those from elsewhere in the world for similar PSP toxin concentrations, which means a longer time to attain concentration limits safe for human consumption. Understanding PSP dynamics is important to avoid large economic losses related to halting mussel production.

First insights into population parameters and spatial distribution of the two morphotypes of Mactra stultorum (brownish and whitish) (Linnaeus, 1758) (Mollusca: Bivalvia) along the southwestern Spanish coast

ABSTRACT The aim of this study was to address an analysis of spatial distribution, reproduction, population parameters and secondary production of the natural beds of the well-defined morphotypes of the clam Mactra stultorum (brownish and whitish variants) along the SW Spanish coast. The main findings showed that the presence and the frequencies of both morphotypes increased near the estuaries of rivers, particularly the Guadalquivir River. However, subtle differences in habitat preferences have been revealed and the brownish variant showed a wider and deeper distribution. High similarity in the gonadal development was recorded for both variants. It started in January, continued into late winter and early spring and ended with a spawning period from April to August. An energy storage-utilization cycle, coupled to the reproductive and resting periods and driven by seawater temperature variations and food availability, was also observed. The abovementioned period of gamete emissions resulted in a recruitment pattern with a one-time settlement period per year. Von Bertalanffy growth functions provided an asymptotic length of 46.7 mm (whitish) and 50 mm (brownish) and growth constants of 0.55 (whitish) and 0.50 year−1 (brownish). The mean annual biomass () ranged between 0.062 (whitish) and 0.076 g AFDW m−2 year−1 (brownish) (AFDW: ash-free dry mass). Individual somatic production showed the highest value at 32 and 34 mm shell length, and annual production (P) ranged between 0.075 and 0.113 g AFDW m−2 year−1, resulting in renewal rate (P/) values between 1.21 and 1.37 for the whitish and brownish variants, respectively. These results provide basic knowledge about the reproduction and population dynamics of this species along the Atlantic coast, particularly in the sandflats near the estuary of the Guadalquivir River. They could also shed additional light upon taxonomic differentiation and clarify the ecological role of both variants when compared with two bivalve sympatric species of the intertidal and subtidal areas.

Genetic structure and diversity of the Chilean flat oyster Ostrea chilensis (Bivalvia: Ostreidae) along its natural distribution from natural beds subject to different fishing histories.

Ostrea chilensis (Küster, 1844), the flat oyster, is native to Chile and New Zealand. In Chile, it occurs in a few natural beds, from the northern part of Chiloé Island (41 ºS) to the Guaitecas Archipelago (45 ºS). This bivalve is slow growing, broods its young, and has very limited dispersal potential. The Ostrea chilensis fishery has been over-exploited for a number of decades such that in some locations oysters no longer exist. The aim of this study was to study the genetic diversity of the Chilean flat oyster along its natural distribution to quantify the possible impact of the dredge fishery on wild populations. The genetic structure and diversity of Ostrea chilensis from six natural beds with different histories of fishing activity were estimated. Based on mitochondrial (Cytb) and nuclear (ITS1) DNA sequence variation, our results provide evidence that genetic diversity is different among populations with recent history of wild dredge fishery efforts. We discuss the possible causes of these results. Ultimately, such new information may be used to develop and apply new management measures to promote the sustainable use of this valuable marine resource.

First Demonstration of Nitrate Reduction Using Woodchip Bioreactor Technology at a Small Community Wastewater Treatment Plant

Eutrophication can be accelerated by excess amounts of reactive Nitrogen (Nr) entering aquatic ecosystems. Historically, the circa 1960 Bolton Wastewater Treatment Plant, Warren County, New York (USA), discharged plant effluent for final polishing to natural sand infiltration beds, which entered the groundwater and then tributaries to Lake George. The absence of a denitrification unit process at the Bolton facility resulted in the construction of a woodchip bioreactor and a corresponding demonstration project to evaluate denitrification of plant effluent prior to sand bed discharge. This Denitrifying Bioreactor (DNBR) installation was the first real time, in-situ application of this “green technology” for a small wastewater treatment plant world-wide. The Bolton DNBR reduced nitrate-nitrogen concentrations in the tertiary effluent by 38% when compared with untreated tertiary effluent. Here we show that wastewater denitrification using this passive, environmentally compatible technology offers a low-cost, effective tool for small community wastewater treatment plants where excess Nr is problematic. Combined with diligent plant operator attention, this innovative treatment should move beyond concept into full scale field applications for other small community wastewater treatment plants globally, using lessons learned at the Bolton facility.

Fish Capacity of a Sand Pit by Zoobenthos of the Sura River Floodplain within Penza Region

Sand pits have great potential in terms of domestic aquaculture development, therefore assessment of their natural fish capacity is essential in terms of food resources. The assessment of fish capacity by zoobenthos in a sand pit deprived of representatives of ichthyofauna was carried out. It was found out that zoobenthos of a sand pit in the flood plain of the Sura river has not rich species composition that varies considerably by seasons with multiple fluctuations of population number and biomass. At the same time the highest values were observed in June, the productivity of zoobenthos increases with increasing water temperature and decreasing water level. By the number of taxa, the number of population and biomass of fodder zoobenthos the sand pit is inferior to the Municipal water storage basin on the Sura river. Fish capacity of forage zoobenthos of the pit by zoobenthos was 14.42 kg/ha, which was 2-3 times lower than in Sursky and City reservoirs, the natural bed of the Sura river. Due to reclamation works in drained pits it is possible to increase the productivity of zoobenthos. In permanently watered pits the cultivation of benthic fishes is rather limited.