Use Of Artificial Substrates Research Articles

Unveiling the role of taxonomic sufficiency for enhanced ecosystem monitoring

The use of Artificial substrates (AS) as sampling devices addresses challenges in macrofaunal quantitative sampling. While effectively capturing biodiversity patterns, the time-intensitive identification process at the species level remains a substantial challenge. The Taxonomic Sufficiency approach (TS), where only taxa above species level are identified, arises as a potential solution to be tested across different environmental monitoring scenarios. In this paper, we analyzed three AS macrobenthic datasets to evaluate the odds of TS in improving the cost-effective ratio in AS monitoring studies and establish the highest resolution level to detect assemblage changes under different environmental factors. Results indicated that the family level emerged as a pragmatic compromise, balancing precision and taxonomic effort. Cost/benefit analysis supported TS efficiency, maintaining correlation stability until the family level. Results also showed that reducing resolution to family does not entail a significant Loss of Information. This study contributes to the discourse on TS applicability, highlighting its practicality in monitoring scenarios, including spatial-temporal studies, and rapid biodiversity assessments. Additionally, it highlights the “second best approach” of family-level practicality depending on the specific monitoring scenario and recognizes the importance of the species-level “best approach” before applying TS in monitoring studies.

The Effect of Artificial Substrate and Carbon Source Addition on Bacterial Diversity and Community Composition in Water in a Pond Polyculture System

The use of artificial substrates and biofloc technology can favor fish culture and improve water quality. The aim of this study was to evaluate whether artificial substrates and carbon source additions modify the microbial activity of water bodies. The diversity and structure of microflora in the water after adding artificial substrates and carbon sources to the ponds were analyzed using high-throughput sequencing based on the V3-V4 region of 16S rRNA genes. The results showed that there was no difference in the richness and diversity of intestinal microflora between the control and experimental groups. Principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) showed that artificial substrate and carbon source addition changed the structure of the microflora. The results of a linear discriminant analysis (LDA) effect size (LefSe) indicated 11 biomarkers in the EGˍst group. Spearman correlation heatmap analysis showed that environmental factors affected the bacterial communities, and the results of a redundancy analysis indicated that chemical oxygen demand was a critical factor in controlling the bacterial communities in the water. These results provide an understanding of the effect of artificial substrate and carbon source addition on bacterial diversity and community composition in water.

Microperiphyton development in lakes and reservoirs

Biofilms play an important role in the material flux of lakes and other aquatic ecosystems, but little is known about the mechanisms controlling their community structure under natural conditions. In the present study, we focused on the use of artificial substrates for the life strategies of microbial communities investigation. Heterotrophic nanoflagellates (HNF) are known as most important grazers of bacteria in the biofilm communities. The Choanoflagellida have an essential role in microbial food webs contributing to a process of self-purification of water bodies as well as sponge choanocytes, filtering large water volumes. Effects of Cyanobacteria and other pathogenic microorganisms on sponges are very similar to the same effects on Choanoflagellida and HNF in the early phase of biofilm colonization. Standard microbial biofilms (model communities) can serve for ecorobots development.

Lessons learned implementing mineral accretion and coral gardening at Agincourt Reef, Great Barrier Reef

SummaryThe health and diversity of coral reefs are critically important to the stability and value of the marine tourism industry. Declines in coral reef health through climate change impacts and cyclones, and associated media coverage, have impacted tourism visitation. In January 2018, a major change in Australian Government policy included a Reef Restoration and Adaptation Program to investigate the best science and technology options for helping the Great Barrier Reef recover and adapt to the changing environment. We report on a trial of two intervention methods, mineral accretion and coral gardening, to improve hard coral recovery at a popular site on the Great Barrier Reef. We installed six artificial reef substrates onto which an equal number of coral fragments of seven species were transplanted over the course of two years. During this time, three of the six treatments were connected to a low‐voltage power source to encourage mineral accretion and enhance coral growth. Electrolysis resulted in substantial mineral accretion on the steel substrate, however, the technology had no positive effect on the survival or growth of transplanted coral colonies. After 13 months, a second round of transplanted coral fragments was undertaken, and the electrolysis was discontinued. Over a four‐year period, mean live coral cover increased significantly in both treatment locations, from 1.7% and 0% to 80.8% and 75.8%, respectively. Control locations increased insignificantly from a mean of 5% to 14.2%. The mineral accretion technology proved technically challenging and did not support the growth or health of transplanted corals, providing no evidence to support the use of mineral accretion technology for this purpose. The technology may, however, have applications in the creation of new, solid substrates and for initial rubble stabilisation efforts. These results demonstrate the effective use of artificial substrates in conjunction with coral gardening techniques for the recovery of hard coral at degraded tourism sites.

Using artificial substrates to quantify Gambierdiscus and other toxic benthic dinoflagellates for monitoring purposes

Collecting methods generally used to determine cell abundances of toxic benthic dinoflagellates (BHAB) use cells dislodged from either macrophytes or artificial substrates. This article compares the advantages of the macrophyte and artificial substrate methods and discusses which method is more appropriate for use in monitoring programs that focus on toxic BHAB species identification and quantification. The concept of benthic dinoflagellate “preference” for specific macrophytes was also reviewed. Examination of data from 75 field studies showed macrophytes with higher surface area per unit biomass harbored higher concentrations of Gambierdiscus cells. There was no definitive evidence that cells were actively selecting one macrophyte over another. This observation supports the use of artificial substrates (AS) as a means of assessing cell abundances in complex habitats because cell counts are normalized to a standardized surface area, not macrophyte biomass. The artificial substrate method represents the most robust approach, currently available, for collecting toxic, benthic dinoflagellates for a cell-based early warning system.

Macroinvertebrates’ response to different land use in lowland streams from Uruguay: use of artificial substrates for biomonitoring

ABSTRACT The use of macroinvertebrates as indicators of water quality is an effective and low-cost tool, which is widely implemented in biomonitoring programmes. Certain taxa are characteristic of impaired watercourses (e.g. Oligochaeta, Chironomidae and Amphipoda), while others are characteristic of good-quality watercourses (e.g. Ephemeroptera, Plecoptera and Trichoptera; EPT). In this work, we evaluated the response of the macroinvertebrate assemblages to different land uses. For this purpose, artificial substrate colonization experiments were conducted in streams including urban (U, n = 3), intensive agriculture and dairy production (AD, n = 4) and extensive cattle ranching (CR, n = 4) land uses. Because in Uruguay pristine ecosystems are practically non-existent and streams of low order streams associated with extensive cattle production represent the lowest deterioration water quality condition, CR sites were used as control reference streams. Physicochemical water parameters were measured. For macroinvertebrate sampling, 10 artificial substrates were installed in each stream. A total of 110 artificial substrates were analysed. Each sample/site consisted of a plastic mesh bag of 1.2 cm opening, which were filled with 160 cm3 (including 73.3 ± 5.8 cm3 interstitial water) of stones sieved between 1.3 and 1.5 cm. During the summer of 2018 (February), devices were left in streams for 15 days for communities to colonize them. U and AD land use represented the stressors with the highest impact on the attributes and composition of the macroinvertebrate communities. Abundance of EPT was higher in CR, meanwhile Caenogastropoda dominated in AD, and Amphipoda in U sites. Macroinvertebrate groups to order level classification were able to effectively discriminate between different land uses. The use of artificial substrate also demonstrated to be efficient method for monitoring macroinvertebrate community. We did not find a correlation between the physicochemical water parameters and the macroinvertebrate community. In this context, we propose a rapid and cost-effective biomonitoring approach, capable of estimating the degree of impact of different land uses.

The use of artificial substrate and materials for nest building in 2 ground-finches (Geospiza spp.) under human-altered conditions

Urbanization is one of the main problems for biodiversity around the world, associated with a decrease of natural habitats and its resources. In contrast, urbanization can also provide new resources that could be used by species that thrive in cities. Understanding why this happens is basic to understand species adaptation to urban areas. Here, we report a nest of a Medium Ground-Finch (Geospiza fortis) built inside a C-purlin beam and artificial materials used for nest building by Medium and Small (G. fuliginosa) ground-finches. The changes that can be observed in some populated areas of the Galapagos Islands, where land cover has been transformed from native habitats into farms, plantations, and urban areas, provide new resources and challenges for native birds and other animals. We discuss the advantages and disadvantages of using artificial materials in nest building and how this may help birds survive in urbanized areas.

Two better than one: The complementary of different types of artificial substrates on benthic marine macrofauna studies

Non-destructive methodologies based on the use of artificial substrates (AS) for quantitative sampling of macrofauna have been used to solve sampling problems in complex benthic environment, such as rocky reefs. The macrofauna assemblages of two different types of AS (dendritic and crevice), at two different locations were studied. The main goal was to evaluate the complementarity of dendritic and crevice AS when sampling the macrofauna associated with rocky environments, in two scenarios: within the same location and between locations. With this approach, we intend to contribute to the development of a non-destructive sampling methodology based on AS. The hypotheses tested were that i) the assemblages associated with each type of AS would differ between them and, ii) regardless of AS type, assemblages would differ between locations. Our results revealed significant differences after three months between the macrofauna assemblages from dendritic and crevice substrates in both locations and differences between locations irrespective of the AS type used. Hence, due to the high number of species that only were attracted by each type of AS and the species settlement preferences, our findings have shown the complementarity of the two types of AS (dendritic and crevice). This suggests that the mixed use of AS could be the best approach to non-destructive standard monitoring programs based on benthic marine macrofauna.

Effects of salinity on growth, competitive interaction and total nitrogen content of two estuarine macrophyte species cultivated on artificial substrate

Salinity can compromise the growth of aquatic macrophytes, influencing their nutrient content and interspecific interactions. In estuaries, the sediment characteristics vary in salinity as well as nutrient availability, granulometry and microbiota. The use of artificial substrates in manipulative experiments allows the evaluation of the isolated effect of salinity on plants. We evaluated the effects of salinity on growth, interspecific interaction and total nitrogen (TN) content of the estuarine macrophytes Spartina alterniflora and Crinum americanum cultivated on expanded vermiculite. We conducted a two-factor experiment (3 cultures × 3 salinities × 5 replicates = 45 experimental units) lasting 185 days in a greenhouse. We cultivated monocultures (8:0 and 0:8) and mixed cultures (4:4) at 0, 20 and 30 ppt salinity levels with the same concentration of nutrient solution. We found that salinity did not influence the growth of S. alterniflora and C. americanum in monoculture. In mixed culture, there was an asymmetric competition, as S. alterniflora limited the growth of the aboveground fraction of C. americanum at higher salinity; however, C. americanum did not limit the growth of S. alterniflora at any treatment. Salinity did not influence the TN content in S. alterniflora. However, C. americanum had greater TN content in the aboveground fraction at higher salinity, possibly as a strategy of salt tolerance. The TN content in the aboveground fraction of C. americanum was lower in the mixed cultures than in the monocultures, indicating an effect of the interspecific interaction.

The effects of artificial substrate and stocking density on Pacific white shrimp (Litopenaeus vannamei) performance and water quality dynamics in high tunnel-based biofloc systems

The use of artificial substrates in shrimp aquaculture may allow for production of shrimp at increased densities while providing a growth medium for microbes that assist with water quality processes and provide supplemental nutrition for shrimp. Greenhouse-based shrimp production systems can extend the shrimp production season in temperate climates while conserving water and energy. For this study, we evaluated the effects of providing extra substrate and shrimp density on water quality and shrimp production in greenhouse-based biofloc systems. Four 11-m3, wood framed, and rubber-lined tanks were constructed in each of four high tunnel greenhouses (for a total of 16 tanks). Four treatments were evaluated: high-density stocking with substrate (HDS), high-density stocking with no substrate (HDNS), low-density stocking with substrate (LDS), and low-density stocking with no substrate (LDNS). Each treatment was randomly assigned to one tank in each tunnel to block for location. No artificial heat was used, and shrimp were grown for 120 days. High-density systems were stocked at 200 shrimp/m³ while low-density tanks had 100 shrimp/m³. Adding substrate increased total in-tank surface area by 13.4%. The addition of substrate had no significant effect on any shrimp production or standard water quality parameters. Shrimp had significantly greater final weight, faster growth rate, and lower feed conversion rate in low-density treatments (P ≤ 0.02 for all). Total shrimp biomass production was significantly higher in high-density treatments (HD: 4.0 kg/m3; LD: 2.3 kg/m3; P < 0.05). There were no significant differences in survival between densities (HD: 91.3%; LD: 94.5%; P = 0.43). Peak and overall mean nitrite levels were significantly higher in high-density treatments compared to low-density treatments. Dissolved oxygen levels and pH over the course of the study were significantly lower in high-density treatments, likely due to increased respiration rates in the water column. This project shows the feasibility of shrimp production in temperate climates with no artificial heat using high tunnel greenhouses, few impacts of added substrate on shrimp production, and increased shrimp density can result in much larger harvests with few negative impacts on production metrics.

Benthic dinoflagellates: Testing the reliability of the artificial substrate method in the Macaronesian region

The suitability of the ‘artificial substrate’ method, i.e. standardized surfaces of fiberglass screens, for the quantification of four benthic harmful algal bloom (BHAB) dinoflagellates (Gambierdiscus, Ostreopsis, Prorocentrum and Coolia) was tested relative to estimates from natural macroalgal substrates. Sampling took place in a variety of intertidal and subtidal coastal habitats under different water motion conditions, at depths from 1 to 7 m, in two archipelagos of the Macaronesia region: The Canary Islands and Cape Verde. An immersion time of 24 h was sufficient to adequately estimate dinoflagellate abundances. Seven replicates were established as the ideal replication level, considering both reproducibility and sampling effort. In most cases, cell abundances of the four dinoflagellate genera showed lower variability on artificial substrates than on macroalgae, leading to more reliable estimates of abundances. The ratio of mean cell abundances on artificial substrates to mean cell abundances on macroalgae highly varied among sampling sites for each genus. This was especially true for Ostreopsis and Coolia. Thus, given the potentially harmful nature of benthic dinoflagellates, the transformation of abundances expressed as cells g−1 of macroalgae to abundances expressed as cells cm-2 is risky, and it should not be attempted in monitoring and management programs of harmful microalgae. In summary, results of this study support the use of artificial substrates in monitoring programs of BHAB dinoflagellates, while the risks of using macroalgae are stressed.

Preliminary investigation on the use of artificial substrates to favor Tritia mutabilis (Linnaeus, 1758) spawning in Central Adriatic Sea: a possible contribution to stock maintenance

Tritia mutabilis, formerly classified as Nassarius mutabilis, represents an important but declining resource for small scale fishery in the central Adriatic Sea, likely due to overfishing. A preliminary investigation on the use of artificial substrates to favour its spawning was carried out in a coastal area off the Abruzzi region, central Italy. Between May and June 2015, five groups of six pyramid structures made of a steel frame covered by plastic net, with a \(0.5 m^2\) surface available for deposition, were placed on sandy bottoms at about 0.5 nautical miles from the coast and at sea depths ranging from 5.5 m to 7.5 m. A density of T. mutabilis egg capsules \(&amp;gt; 1 per 100 cm^2\) was observed in two of the pyramid groups. The number of embryos present in each capsule ranged from 8 to 22 (mean number: 14). At the end of the study, almost all the capsules presented an apical opening and were empty, thus indicating successful hatching and larval release. This preliminary investigation shows that the natural deposition of T. mutabilis egg capsules can be facilitated by placing artificial substrates on sandy bottoms and it is conceivable that their use would contribute to maintain sustainable stocks of this species.

Assessing the use of artificial substrates to monitor Gambierdiscus populations in the Florida Keys

Four distinct coastal locations were sampled on a monthly basis near Long Key (Florida Keys, USA) over a 13-month period to study Gambierdiscus population dynamics on different substrates, including four macrophyte species (Dictyota spp., Halimeda spp., Laurencia spp., and Thalassia testudinum) and three artificial substrates (polyvinyl chloride (PVC) tiles, burlap, and fiberglass window screen). Cell densities of Gambierdiscus were generally lower on Dictyota versus Halimeda and Laurencia. Cell densities of Gambierdiscus were significantly correlated among macrophyte hosts in 54% of the comparisons, and between macrophyte hosts and artificial substrates in 72% of the comparisons. Predictive slopes determined from regression analyses between cell densities on artificial substrates and macrophyte hosts indicated that, on an areal basis, fewer cells were present on macrophytes versus artificial substrates (cells cm−2) and that slope variation (error) among the different macrophytes and sites ranged from 5% to 200%, averaging 61% overall. As the data required log-transformation prior to analyses, this level of error translates into two-orders of magnitude in range of estimation of the overall average abundance of Gambierdiscus cells on macrophytes (135 cells g−1 wet weight); 20–2690 cells g−1 ww. The lack of consistent correlation among Gambierdiscus cell densities on macrophytes versus artificial substrates, coupled with the high level of error associated with the predictive slope estimations, indicates that extreme caution should be taken when interpreting the data garnered from artificial substrate deployments, and that such deployments should be thoroughly vetted prior to routine use for monitoring purposes.

Nesting stingless bees in urban areas: a reevaluation after eight years

Studies of nesting ecology have proven to be extremely important for stingless bee conservation. These studies have rarely been conducted in urban landscapes, and even fewer have compared species diversity and abundances over time. We surveyed native stingless bee nests at the Federal University of Juiz de Fora campus in Minas Gerais, southeastern Brazil, from May 2008 to April 2009. We recorded the number of nests, nest height, species diversity, and nest substrate type (i.e., natural or artificial). We compared our results to those of a similar survey carried out in the same location eight years prior (2000/2001) in order to evaluate how urban expansion on campus has influenced the Meliponini bee community. Stingless bee abundance and richness were greater in the second survey. The use of natural substrates decreased, while the use of artificial substrates increased. This suggests that the increase in man-made structures on the UFJF campus has provided favorable sites for establishment of some stingless bee species.

Substrate Selectivity and Food Preference of the Caprellid Amphipod (Caprella Penantis); Evaluation of a Possible Aquaculture Resource for Marine Hatcheries

Marine aquaculture is growing at a significant rate with an increasingly diverse range of fish being cultured In order to maintain and enhance the growth and prosperity of the industry additional feed sources are required for different fish species Caprellid amphipods have been identified as a possible candidate for exploitation as an aquaculture live feed Caprella penantisis a globally distributed caprellid species found in the littoral zones of many coastal habitats throughout the world Like several other species it has been acknowledged as one of the most suitable species for culture due to its diverse range and wide environmental tolerances This paper examined the survivability of C Penantis when reared on different substrate types in closed systems Laboratory experiments used L carboys as culture vessels with each being equipped with a particular culture substrate The substrates that were tested in this experiment included natural substrates artificial substrates and no substrate and consisted of Sargassum spp seaweed and rope respectively In addition feeding habits uptake and population growth performance on each of the different substrate types were observed monitored and assessed over a sixteen week trial period The use of artificial substrate produced the highest survivability and population growth in addition to the highest feed uptake Average survival for populations of the control natural and artificial substrate groups were and respectively suggesting that artificial substrate is the most suitable culture medium for this particular caprellid The study found the culture of caprellids to be of relatively high labour intensity particularly when compared with currently used live feeds they are perhaps therefore best suited for use in small scale mariculture systems that have been established for the production of high value species

Effect of degradation of poly(epsilon-caprolactone) films on functional properties for tissue engineering bioreactors

Event Abstract Back to Event Effect of degradation of poly(epsilon-caprolactone) films on functional properties for tissue engineering bioreactors Nazely Diban1, Sandra Sanchez-González1, Inmaculada Ortiz1 and Ana M. Urtiaga1 1 University of Cantabria, Department of Chemical and Biomolecular Engineering, Spain The regeneration of the central nervous system (CNS) is one of the major challenges that regenerative medicine faces nowadays. In order to promote in vitro neural cell regeneration, the use of artificial substrates may provide support for the neural cell growth and axon regeneration [1]. The scaffolds used in the tissue engineering bioreactors must provide sufficient mechanical stability and high transport of nutrients towards the cells and good removal of the metabolites during the whole lifetime of the in vitro cultures. The scaffold porous structure and hydrophilic character are important properties determining the mechanical and mass transport performance and the functionality of the scaffolds for this application. Scaffolds of biodegradable and biocompatible polymers have been proven as promising substrates to promote cell adhesion and proliferation [2]. The scaffolds must provide an adequate functionality in the bioreactor during suficient time so the regeneration of the tissue occurs simultaneously with the lost of functional properties of the scaffold due to degradation. In our previous work [2], flat Poly(ε-caprolactone) (PCL) films with adequate morphology to allow neuronal tissue growth were fabricated using a phase inversion casting technique and isopropanol (IPA) as coagulant (Figure 1). PCL is a polyester that degrades through a characteristic hydrolitical mechanism. In this work, we explore the effect of degradation on the structural (aspect, porosity, morphology), mechanical and transport properties (water and model ovine serum albumim solution transport) of the PCL films under the typical bioreactor conditions (37 ºC in a Phosphate Buffer Solution (PBS) at pH 7.4). The adequacy of the change of the functional properties to match the neural celular proliferation rate will be studied. Figure 1. SEM images of the cross section and surface of the PCL films and confocal images of U87 human glioblastoma static cell culture after 48 hours on the PCL films. All cell nuclei are shown in blue, and the actin cytoskeletal architecture is show in green. Financial support of the Cantabria Explora call through project JP03.640.69 is gratefully acknowledged

Chironomidae and Oligochaeta for water quality evaluation in an urban river in southeastern Brazil.

Considering the importance of benthic macroinvertebrates for diagnosis of variations in the ecological conditions of aquatic habitats, the aim of this study was to investigate the structure of the Chironomidae and Oligochaeta assemblages along an organic pollution gradient. The fauna specimens were obtained with the use of artificial substrates, and the environmental variables were recorded at five sites of the São Lourenço River, during 12months. Metrics of the assemblage and detrended correspondence analysis were used to verify the response of the fauna to the pollution gradient. Procrustes analysis was used to verify whether the data on the Chironomidae and Oligochaeta assemblages, as well as the taxonomic and numerical resolution of these groups, provide similar results in relation to the pollution gradient. The richness, evenness, and taxonomic composition of the Chironomidae and Oligochaeta assemblages varied significantly among the collection sites, with distinct conservation conditions. Genera of the subfamilies Orthocladiinae and Tanypodinae were associated with the sites upstream of the urban area, where the dissolved oxygen levels are higher. Species of Oligochaeta and the genus Chironomus were associated with more organically polluted sites. No concordance was observed in the response of the Chironomidae and Oligochaeta assemblages in relation to the environmental variables, indicating the need to use both groups in biomonitoring studies. On the other hand, both the data on composition (presence or absence) and those on the lowest taxonomic resolution (abundance of subfamilies) were effective to diagnose the pollution gradient in the river studied. Therefore, when the environmental conditions along a river's gradient are contrasting, we suggest the use of the lowest taxonomic resolution of Chironomidae and Oligochaeta in biomonitoring. That procedure considerably reduces the assessment time, besides being a method that can be used by people not specializing in the taxonomy of groups.

Use of artificial substrate in pond culture of freshwater prawn (Macrobrachium rosenbergii): a new approach regarding growth performance and economic return

An experiment was conducted for six months to evaluate the effects of artificial substrates on the survival, growth and production of Macrobrachium rosenbergii juveniles. The T1 contained locally available bamboo-made substrate both vertical and horizontal and T2 received no substrate. Juvenile prawns (0.40±0.13 g) were stocked at the rate of 19,760 prawns ha-1. The water quality parameters range such as temperature, pH and DO were 22.06-33.45°C, 7.70-8.40 and 4.75-6.15 mgl-1 respectively which was no significant difference (P&lt;0.05) between two treatments. The final weight was 56.48±6.56 g and 45.03±2.11 g in T1 and T2 respectively. The survival rate of T1 was 63.12% which was significantly higher (P&gt;0.05) than T2 (56.87%). The specific growth rate, food conversion ratio and protein efficiency ratio were 1.19 % and 1.14 %, 3.15 and 4.39, 0.98 and 0.71 in T1 and T2 respectively which were not significantly different (P&lt;0.05) between treatments. The total production and net profit in T1 was 1408 kgha-1 and BDT 117,325 ha-1 which was significantly higher (P&gt;0.05) than T2. Thus growth and survival of prawn juveniles improved in presence of artificial substrate which could be economically viable technique for the freshwater prawn culture.

Use of artificial substrate in pond culture of freshwater prawn (Macrobrachium rosenbergii): a new approach regarding growth performance and economic return

An experiment was conducted for six months to evaluate the effects of artificial substrates on the survival, growth and production of Macrobrachium rosenbergii juveniles. The treatment T1 contained locally available bamboo-made substrate both vertical and horizontal and treatment T2 received no substrate. Juvenile prawns (0.40±0.13 g) were stocked at the rate of 19,760 prawns ha-1. The water quality parameters range such as temperature, pH and DO were 22.06-33.45°C, 7.70-8.40 and 4.75-6.15 mgl-1 respectively which was no significant difference (P&lt;0.05) between two treatments. The final weight was 56.48±6.56 g and 45.03±2.11 g in T1 and T2 respectively. The survival rate of T1 was 63.12% which was significantly higher (P&gt;0.05) than T2 (56.87%). The specific growth rate, food conversion ratio and protein efficiency ratio were 1.19 % and 1.14 %, 3.15 and 4.39, 0.98 and 0.71 in T1 and T2 respectively which were not significantly different (P&lt;0.05) between treatments. The total production and net profit in T1 was 1408 kgha-1 and BDT 117,325 ha-1 which was significantly higher (P&gt;0.05) than T2. Thus growth and survival of prawn juveniles improved in presence of artificial substrate which could be economically viable technique for the freshwater prawn culture.

Complexity for Artificial Substrates (CASU): Software for Creating and Visualising Habitat Complexity

Physical habitat complexity regulates the structure and function of biological communities, although the mechanisms underlying this relationship remain unclear. Urbanisation, pollution, unsustainable resource exploitation and climate change have resulted in the widespread simplification (and loss) of habitats worldwide. One way to restore physical complexity to anthropogenically simplified habitats is through the use of artificial substrates, which also offer excellent opportunities to explore the effects of different components (variables) of complexity on biodiversity and community structure that would be difficult to separate in natural systems. Here, we describe a software program (CASU) that enables users to visualise static, physical complexity. CASU also provides output files that can be used to create artificial substrates for experimental and/or restoration studies. It has two different operational modes: simple and advanced. In simple mode, users can adjust the five main variables of informational complexity (i.e. the number of object types, relative abundance of object types, density of objects, variability and range in the objects’ dimensions, and their spatial arrangement) and visualise the changes as they do so. The advanced mode allows users to design artificial substrates by fine-tuning the complexity variables as well as alter object-specific parameters. We illustrate how CASU can be used to create tiles of different designs for application in a marine environment. Such an ability to systematically influence physical complexity could greatly facilitate ecological restoration by allowing conservationists to rebuild complexity in degraded and simplified habitats.