Pond Size Research Articles

Stocking Hatchery-Produced Mola (<i>Amblypharyngodon mola</i>) Seed in Carp Polyculture Ponds: A Performance Assessment in Odisha, India

Small indigenous fish species (SIS) such as mola (Amblypharyngodon mola) regarded as natural ‘superfoods,’ due to their high nutrient content, offer a promising avenue for addressing the nutritional deficiencies in India. Over the past decade, integrating mola into conventional carp polyculture systems has emerged as a promising nutrition-sensitive innovation, significantly enhancing micronutrient intake, particularly for women and children. However, the lack of hatchery-reared mola seed has hindered the sustainability of this approach. Recently, this bottleneck was addressed by developing a hatchery-based mass seed production protocol for mola, which was introduced into carp farming systems on a pilot basis. This study evaluates the performance of hatchery-produced mola seed inhomestead carp polyculture ponds in Odisha, India by using a field survey. Of the surveyed farmers, 24% purchased mola spawn, while 76% opted for mola fry. The average pond size of surveyed farmers was 0.32 ha with an average culture duration of 9months. Farmers stocked mola spawn at an average density of 283,583/ha and fry at 22,190/ha. Results showed that 93% of farmers achieved successful mola production, with an average mola yield of 194 kg/ha and total production of 2831 kg/ha. Molacontributed an average of 9% to the total fish production reaching a maximum contribution of up to 26%. The mola fish contributed significantly to the household in terms of additional revenue. Household consumption averaged 14 kg of mola per year, with a per capita consumption of 3 kg. Increasing pond size and optimizing stocking density emerge as critical factors positively impacting mola production and income. Overall, this study demonstrates the potential of hatchery-produced mola seed in promoting nutrition-sensitive aquacul-ture in Odisha, offering valuable insights for its scaling up.

Evaluation of Indian white shrimp (Penaeus indicus) rearing technique at Balai Besar Perikanan Budidaya Air Payau (BBPBAP) Jepara

Abstract Indian white shrimp is one of the important fishery commodities with high economic value after banana prawns (Penaeus merguiensis) in the northern coastal waters of Central Java Province. This shrimp needs to be more developed since its aquaculture technique was not quite as well-known as in other shrimps such as P. vannamei or P. monodon. This study aimed to unveil the techniques for rearing white shrimp and its influencing factors. The method in this research used active participation and descriptive methods. The data collection method used was from primary and secondary data. Both primary data were FCR (Feed Conversion Rate), ABW (Average Body Weight), ADG (Average Daily Growth), and water quality parameters while the secondary data were literature review and staff information. The results showed that the FCR values in the three pools were high (1: 5.5, 2: 24.57, 3: 10.36). For growth parameters, the ABW values for the three ponds were 29.57, 20.00, and 23.91 while the final ADG values were 0.53, 0.14, and 0.52 respectively. It can be concluded that the enlargement activity of Indian white shrimp needs to be improved due to high FCR value and fluctuating water quality. Higher FCR value would reduce the feed efficiency so that a lot of feed was given to the shrimps but their growth is less than optimal. The Enlargement activities at Jepara should use feed with a minimum protein content of 33% by the protein requirements of Indian white shrimp so that it can support gonad maturity. Additionally, it is necessary to rearrange the pond size to conform to the standard size (2000-5000 m2), as well as manage water quality through daily siphoning so that the water quality remains optimal.

Post‐fire sediment attenuation in beaver ponds, Rocky Mountains, CO and WY, USA

AbstractWe evaluated the post‐fire sediment dynamics in beaver ponds to examine these ponds' contributions to sediment storage following disturbance. Beaver dams and beaver mimicry structures impound water and sediment, a function that is of growing interest in wildfire‐prone landscapes. Wildfires typically lead to high sediment loading into rivers in the years following fire, constituting a disturbance to aquatic ecosystems and a challenge to water resource managers. Previous work establishes that beaver dams trap substantial volumes of sediment, but sedimentation appears spatially and temporally heterogeneous and it remains unclear the extent to which short‐term pulses of sediment are attenuated by these structures. We examine the conditions under which beaver dams and beaver mimicry structures store post‐fire sediment by quantifying the sediment volume of 40 ponds, about half of which were burned in large wildfires in the Colorado and Wyoming Rocky Mountains in 2020. The median relative volume of burned ponds is 85%, which is greater than the median for unburned ponds (58%), meaning that burned ponds store higher relative volumes of sediment when pond size is accounted for. Furthermore, sediment accumulated at a median rate of 3.0 cm/year over the entire history of the pond. Post‐fire sedimentation rates, with a median of 20.4 cm/year, were an order of magnitude higher than pre‐fire rates with a median of 1.8 cm/year. In addition, vegetation and geomorphic characteristics correlated with sediment storage in ponds. Sediment surveys confirmed that ponds with greater surface areas contain higher volumes of sediment. Additionally, older ponds and ponds abandoned by beavers stored higher volumes of sediment compared to recently constructed ponds, ponds actively maintained by beaver, and beaver mimicry structures. These findings demonstrate that beaver ponds and mimicry structures may function as sediment sinks capable of attenuating post‐fire sediment. The biogeomorphic context, defined across multiple scales from the pond to the catchment, provides additional explanation for the wide range of sediment storage observed and remains an important consideration for beaver‐based restoration, catchment sediment management, and resilience evaluation.

Economics of Fresh Water Cultured Fish Production in Odisha and Bihar, India: A Comparative Analysis

Fisheries and aquaculture are important sectors that provide nutritional security, contribute to agricultural exports, and provide livelihoods to about 28 million fishermen, fish farmers, and other value-chain actors. The study was conducted in two states of Eastern India, i.e. Odisha and Bihar, to estimate the comparative economics of freshwater fish production and its profitability. The results showed that the cost of fish production was estimated to be Rs. 346943.45/ha of pond, constituting Rs. 208582.74 as a variable cost and Rs.138360.71 as a fixed cost in Odisha. In Bihar, the per hectare fish production for an average pond size was estimated to be Rs. 318445.47, comprising variable cost as Rs 188061.82 and fixed cost as Rs. 130383.64. On average, per hectare, fish production in Odisha from all ponds was estimated to be 45.69 quintals, while in Bihar, it was 35.67 quintals. The profitability analysis revealed that in Odisha, per hectare gross income, on average, for all ponds was Rs. 717763.06. In the case of Bihar, the gross income for all the ponds was calculated to be Rs. 540352.02/ha. It was concluded that returns on investments in all pond categories were comparatively higher in Odisha than in different pond size groups of Bihar.

Profitability Level of Fish Farming In Ife-Ijesa Agricultural Development Programme, Osun State, Nigeria

The objective of this paper is to estimate the profitability level of fish farmers in Ife-ijesa zone of Osun State Agricultural Development Programme (OSADEP), Nigeria using standard procedures of structured questionnaires administered to 100 respondents that were randomly selected. The study revealed that fish farming in the Area was male dominated with 89%. For the respondents using earthen 41.3% were range between50-60% and 31.6% of the respondents using concrete were within the range of 50-60years. 70.3% of the respondents using concrete were married and 56.6% of the respondents using earthen were married. 40.5% of the respondents using concrete had tertiary education and 45.2% of the respondents using earthen had tertiary education. 95.7% of the respondents using earthen operate by self-savings and 98.1% of the respondents using concrete also operate by self-saving and the average pond size used was 0.5 hectares. Findings also showed that the estimated average fixed cost and variable cost incurred for all fish farmers were N109.296.43 for the respondents using concrete and N173,473.38 for the respondents using earthen, while gross margin and average farm profit were N108, 718,43 for the respondents using concrete and N172,734.88 for the respondents using earthen per annum respectively.

Impact of soil and water quality on the sustainable management of mangrove-compatible brackishwater aquaculture practices in Indonesia

The widespread degradation of mangroves has been attributed to their conversion into other land uses and purposes, most notably their destruction to construct extensive brackishwater aquaculture ponds. This study investigated the relationship between environmental factors and management alternatives for an integrated mangrove-aquaculture system in Derawan Island District, Berau Regency, East Kalimantan Province, Indonesia. The study collected a total of 56 soil and water samples from around 50 ha to assess environmental limiting factors for integrated mangrove-brackishwater aquaculture management. The measured soil quality variables included field pH (pHF), pH of hydrogen peroxide extract (pHFOX), peroxide oxidizable sulfur (SPOS), pyrite (FeS2), organic matter (OM), nitrogen-total (N-TOT), iron (Fe), and aluminum (Al). Water quality variables included salinity, temperature, pH, dissolved oxygen (DO), different forms of nitrogen (NH3–ammonia, NO3–nitrate, and NO2–nitrite), phosphate (PO4), Fe, and total organic matter (TOM). The study employed a hydrological restoration approach to suggest a mangrove-friendly aquaculture pond design and layout. The study generally showed that Acid Sulfate Soils (ASS) significantly restricted the existing mixed-mangrove aquaculture pond management by negatively impacting water quality. This study highlights that, given the characteristics of ASS-affected aquaculture ponds, reducing pond size for shrimp culture (mangrove-to-pond ratio of 80% and 20%) will simplify managing ASS environmental limiting factors through cost-effective remediation techniques and a Balanced Fertilization Strategy (BFS). The reduced shrimp pond size will also provide direct opportunities for mangrove restoration and allow effective hydrological restoration. The economic benefit of the proposed pond design and management model focuses on diversifying production units which include shrimp aquaculture ponds, milkfish or tilapia culture in the peripheral canals of the mangrove compartment, juvenile shrimp production, and periodic harvest from the primary pond canal. The study findings are particularly applicable to ponds that have already been built in ASS to improve productivity in addition to supporting the mangrove rehabilitation program. Converting mangrove and ASS-affected land is not advisable for constructing new aquaculture ponds.

Comparative Study of Hydrobiological Parameters Between Earthen and High-Density Polyethylene (HDPE) Brackishwater Shrimp Ponds in Ratnagiri, Maharashtra

The current study was carried out to compare the hydrobiological characteristics of a selected shrimp farm in district Ratnagiri taking pond size, stocking density and culture practices into consideration. For sampling, four earthen and four high-density polyethylene (HDPE) ponds were chosen. Most of the water parameters showed significant difference with respect to different types of ponds (earthen and HDPE) viz. temperature, pH, salinity, dissolved oxygen, alkalinity and net primary productivity (NPP) of both crops (p<0.05). First crop showed significant difference among all water parameters except biochemical oxygen demand (p<0.05). Second crop (January-May) showed significant difference (p<0.05) among all parameters except hardness, ammonia, nitrite, gross primary productivity (GPP) and community respiration (CR). Phytoplankton showed significant difference (p<0.05) with respect to different types of ponds for both crops and zooplankton showed significant differences (p<0.05) only during first crop. Results indicated that high-density polyethylene (HDPE) ponds have greater consistency in water quality characteristics than earthen ponds, which could contribute to enhanced shrimp growth and survival.

Patterns and correlates in the distribution, design and management of garden ponds along an urban–rural gradient

Urbanisation results in the loss and alteration of natural wetlands and ponds. However, garden ponds in cities and towns can potentially act as rich reservoirs of aquatic biodiversity and stepping stones for dispersal. Homeowners with a range of different motivations, including biodiversity values, install garden ponds. Here, our main aim was to study whether the design and management choices of garden pond owners depended on the location of ponds (capital city vs. countryside), when ponds were installed (pond age), or whether fish were introduced. We surveyed 834 garden pond owners across Hungary using a citizen science questionnaire, asking questions on pond size, location, construction date and materials, vegetation structure, introduction of fish and management practices. From 753 validated responses, we found that the introduction of fish into ponds and high urbanisation were strongly associated with local features and management practices, especially large ponds with a water circulation feature, irrespective of pond age. A typical garden pond in Hungary is ~ 20 m2, < 10 years old, made of rubber lining, contains fish, aquatic vegetation and circulating water, and is actively managed. There was a spatial separation of ponds based on local features between ponds in the capital city (Budapest) and elsewhere. These findings suggest that garden pond owners in the city were more likely to make different choices in pond design and management compared to owners in regional areas. Our results also suggest that pond owners may primarily select management practices to improve habitat quality for ornamental fish. Our findings have important implications for maintaining aquatic biodiversity in urban areas, where garden ponds may be the only aquatic habitat available.

Diversity and distribution of chironomids in Central European ponds.

Ponds are common freshwater habitats in the European landscape that substantially contribute to local and regional biodiversity. Chironomids often dominate invertebrate communities in ponds but are usually disregarded in ecological studies due to relatively complicated taxonomy and identification issues. We present a comprehensive overview of the chironomid diversity in 246 ponds spanning a wide range of conditions extending from the Pannonian Plain to the Carpathians. Altogether, we recorded 225 taxa including 192 species from six subfamilies (Podonominae, Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae). However, the chironomid taxa inventory is far from complete and about 16% of the total diversity of pond-dwelling chironomids remains undetected. Chironomid alpha diversity showed a significant unimodal pattern along the elevation gradient with the highest number of taxa per pond expected around 790 m a.s.l. Gamma diversity also peaked in mid-elevations (600-800 m), and the common chironomid taxa partitioned the 2100-m long altitudinal gradient relatively evenly. The heterogeneity of chironomid communities among ponds measured as beta diversity was significantly higher in elevations below 800 m. Temperature and the proportion of surrounding forests significantly influenced alpha diversity of chironomid communities, while urban land cover and pond size had no significant effect. Ponds with a mean annual air temperature of approximately 4.8°C and a low proportion of surrounding forests are expected to harbour the most diverse chironomid communities. Our study showed that chironomids represent a very diverse and often exceptionally rich group of pond-dwelling macroinvertebrates. Given the high diversity and broad range of occupied niches, chironomids should not be overlooked in pond ecology studies. On the contrary, they should be considered a potential model group.

Aquaculture: A hidden goldmine for the rural poor—A cost–benefit analysis of fish farming for sustainable development and food security in Vihiga County, Kenya

AbstractIn Kenya, aquaculture plays a significant role in enhancing the livelihoods of rural communities by boosting the local economy and diversifying protein sources. Although Vihiga County in Western Kenya boasts considerable potential for aquaculture, it paradoxically experiences some of the highest levels of poverty and malnutrition in the country. The profitability of fish farming has also been affected by inefficiencies and poor resources, disproportionately affecting the income and nutritional value of rural poor who rely on Aquaculture as a source of cheap protein. The study was conducted in Vihiga County to assess the cost–benefit of aquaculture production, selecting 100 fish farmers through a stratified random sampling technique from five sub‐counties. A descriptive research design was employed, and data analysis was conducted using correlation and regression analysis with SPSS. Budgetary techniques were used for the cost–benefit analysis. Data presentation was by comparing the mean and standard deviation in US dollars of different pond size production. The research findings indicated that the size and type of pond do not have a significant correlation and differences in production (p‐value &gt;.05). There is a strong positive correlation between the size of the pond and the stocking density. The variable cost (VC) has a positive correlation with pond productivity meaning that an increase in VC leads to an increase in production. And is not statistically significant (p‐value = .21827, p‐value &gt;.05). Moreover, the total cost (TC) correlation is statistically significant (p‐value = .0351, p &lt; .05). Larger ponds are more profitable but require higher costs production than smaller ponds. The study concludes that pond size significantly impacts productivity, advocating for smaller ponds to achieve higher net returns with lower production costs. Major challenges include high costs of feeds, inputs, fish diseases, and post‐harvest losses. Key policy variables influencing aquaculture in Vihiga County include infrastructure, fish feed production, capital, and fisheries extension services. Adequate financial support from both National and County governments is crucial for sustainable aquaculture in alignment with Kenya's Vision 2030 and Global Sustainable Development Goals. Policymakers are urged to assist small‐scale farmers with financing, training, and market information to optimize returns on investment.

Exploitation and survival of Yellow Perch introduced into community ponds

Increased urbanization paired with stagnant or decreasing fishing license sales has bolstered the importance of community fishing programs. Community fisheries require fish introductions, have highly variable chemical and physical characteristics, and are situated in urban settings with non-traditional fishers that can prefer unique species. Community ponds also often receive high angling pressure and exploitation that can hinder the establishment of sustainable populations. We evaluated angler exploitation and its effects as well as biotic (i.e., stocking density, predator relative abundance) and abiotic (i.e., water temperature, pond size, pond depth) factors affecting survival of stocked adult Yellow Perch Perca flavescens in community ponds. We tagged 580 adult Yellow Perch (≥150 mm) and stocked them into four community ponds at 74 or 148 fish/ha in September 2018. We collected two years of fishery dependent (angler tag reporting) and independent recapture data to estimate angler exploitation and survival of Yellow Perch using a joint live-recapture and dead-recovery model. We estimated anglers harvested 44% (95% CI ± 6%) of stocked Yellow Perch across the four ponds in two years, with the majority (81%) coming from one pond. Additionally, anglers harvested 66% of captured Yellow Perch and harvest probability increased with fish size. Seasonal exploitation ranged from 0% to 37% and was more prevalent in cold water seasons. Yellow Perch survival was negatively related to harvest (β = −0.14; 95% CI = −0.17 to −0.10) and a quadratic effect of water temperature (temperature: β = 0.28; 95% CI = 0.02–0.53; temperature2: β = 0.01; 95% CI = −0.01–0.01). Yellow Perch survival was not related to stocking density or pond characteristics. After two years, cumulative survival in three ponds ranged from 0.83 to 0.87 whereas survival in one pond with high exploitation was 0.22. Our results suggest Yellow Perch can be successfully introduced in community fisheries, but populations may not be sustainable when harvest is high. Thus, management strategies to mitigate excessive harvest or multiple put-and-take stockings may be necessary to maintain Yellow Perch populations in community fishing programs.

Untangling the roles of centrality and environmental contribution in diversity patterns across spatial scales

AbstractThe application of graph theory to metacommunity ecology allows a deeper analysis of the effect of network structure on diversity patterns. Here, we set out to test the role of network centrality metrics and environmental characteristics in diversity patterns of pond macroinvertebrate metacommunities. We tested two approaches to construct the networks: one used the percolation distance, whereas the other was based on a community‐contingent distance. The role of each patch within the network was then analyzed using its centrality value. Later, we analyzed the relationships between the macroinvertebrate diversity and centrality metrics for four study sites. The calculated diversity metrics cover different facets of biodiversity at two scales: pond and pondscape. Environmental characteristics of the studied ponds were also included. All relationships were tested considering the entire macroinvertebrate dataset, but also differentiated by dispersal mode (i.e., active vs. passive) and considering the two types of network approaches analyzed. The results were mostly consistent when comparing the network approaches used. Centrality metrics tended to be positively related to alpha and negatively to beta diversity. Environmental uniqueness showed a positive effect on beta diversity metrics, regardless of the dispersal mode. We only observed a weak negative relationship between eutrophication and species richness of active dispersers. Pond size showed a positive effect on both alpha and beta diversity, but was detected more frequently on alpha diversity metrics. We could not find evidence for a clear negative effect of habitat degradation on diversity. We found a greater importance of environmental characteristics versus the centrality metrics for both alpha and beta diversity of active dispersers, while a combination of their contributions for passive dispersers. An unexpected importance of centrality was observed for alpha diversity of passive dispersers. Using empirical data, we demonstrate that the centrality of a patch in an undirected network affects diversity regardless of the approach used to construct the networks, with a higher influence at local scale regardless of the dispersal mode. This study broadens knowledge of the relationships between environmental features and network centrality, demonstrating the important role of centrality as a determinant of diversity in metacommunities.

Bussiness Management System Of Catfish Cultivation Using Fuzzy Inference System Tsukamoto Methods

Catfish is a type of freshwater fish that is in great demand among people because it has high nutritional value. The high demand for catfish on the market is a promising business opportunity. The relatively fast maintenance period makes this cultivation much in demand. Management of a catfish farming business requires good strategy and planning so that the business process can provide optimal profits. Appropriate management practices, good planning can predict crop yields with minimal error rates. Based on past data from catfish farming businesses, catfish pond production results are influenced by several factors including pond area, number of seeds, and amount of feed. The catfish cultivation management system produces predictions of catfish harvest but ignores weather conditions, natural disasters and infectious diseases. The method used in crop yield prediction management is the Tsukamoto Fuzzy inference system. The Tsukamoto method applies monotonous reasoning and rules are built using expert knowledge, enabling the system to be able to conclude and manage predictions of catfish harvest based on data regarding pond size, number of seeds and amount of feed. System testing using 10 data shows prediction results obtained through manual calculations and system calculations, resulting in identical results. Further testing uses the white box method to ensure that the data implemented in the Tsukamoto fuzzy management system accurately produces logical decisions. Hence, it can be concluded that the management system using the Tsukamoto method is able to show effective performance in predicting harvest results based on data on pond area, number of seeds and amount of feed consumption. This management system is expected to be able to provide recommendations for catfish cultivation business planning for the community.

Does Microfinance Participation Affect Food Insecurity? An Empirical Evidence from Fish Farmers in Osun State, Nigeria.

Nigeria at the moment is currently experiencing a surge in prices of food items with inflation on the rise. Although food insecurity affects the entire world, it is more severe in developing countries; hence, the need to examine the impact of Microfinance Participation on food insecurity among fish farming households in Osun State, Nigeria. A total of 284 respondents who are into fish farming were used for this study. Household food insecurity access scale (HFIAS) and Recursive Bivariate Probit Regression Model were used for the analysis and the impact study. The findings from this research established that most of the fish farming households were food insecured (86.6%) while only a few were food secured (13.4%). Age, years of education, household size, pond size, farming as major occupation and fish farming experience significantly influenced microfinance participation. Conclusively, microfinance participation is established to reduce food insecurity among fish farmers in Osun State, Nigeria. It is recommended therefore, that there should be establishment of more microfinance institutions which will be strictly for fish farmers so as to reduce their food insecurity status and other fish farmers who are not into microfinance participation be encouraged to do so through effective extension agent services.

Experimental investigation of the partitioning of radiation in the melt pond–ice–ocean system

To study the partitioning of solar radiation over the melting Arctic sea ice and address the lack of systematic measurements of the optical properties of melt ponds and the underlying ice, four experiments in non-Arctic regions were designed to explore the distribution of solar irradiance on pond surface, pond bottom, and underlying ice. These experiments also investigated the influence of different pond depths (Hp), underlying ice thicknesses (Hi), and melt pond sidewall conditions (i.e., the black sidewalls, ice sidewalls, and pond horizon size) on the apparent optical properties (AOPs) of melt ponds. The black sidewalls with a small pond radius (barrel experiment) showed the greatest influence on the AOPs, significantly lowering the albedo and transmittance, and increasing the energy absorbed by the pond (Ψp) and underlying ice (Ψi). Different sidewall types, such as the black and ice sidewalls, did not affect the AOPs' trend, but affected their values. The AOPs were also influenced by pond size. The albedo linearly decreased and Ψp linearly increased with the increase of pond radius. The albedo and Ψp were almost independent of pond radius as pond radius larger than 0.58 m and 1.25, respectively. The black sidewalls experiment, in which the pond radius was 2.5 m, and the pond size experiment showed that solar energy was mainly absorbed by the melt pond. Ψp increased from 19% to 62%, which corresponded to Hp increasing from 5 cm to 35 cm in the pond size experiment. The results of the four experiments were consistent with the values obtained from numerical simulations and in situ measurements in the Arctic. The experiments conducted in this study were shown to be effective tools to complement and verify the optical measurements of Arctic melt ponds. They allow us to obtain the key information in Arctic pond measurements, which is difficult to achieve due to the severe weather conditions and marine environment.

Karadeniz Somonunun Yolculuğu: Havuzdan Sofraya

Black Sea salmon is from the Salmonidae family and is an endemic species distributed in the Black Sea. These fish, which exhibit anadromous behavior, prefer parts of rivers close to their source for reproduction and the Black Sea for feeding. The first cultivation study of this species, which has high consumer preference and economic value, was started by SUMAE in 1998. As a result of 24 years of work, F7 generation broodstock was created. In order to popularize the production of the species, the private sector was supported with broodstock. In this study, the breeding process of Black Sea salmon was examined and the introduction of the species was aimed. Today, 25 private sector enterprises have production licenses and many enterprises carry out commercial production of the species in the form of trial production with 1603 tons in total. Commercial production is concentrated in the Eastern Black Sea Region, which is the natural distribution area of the species. While enterprises that produce portion size in ponds and have restaurants prefer the red-spotted stream ecotype in production, enterprises that produce large-sized fish in dam lakes and the sea prefer the marine ecotype, which reaches sexual maturity late and has a better growth performance than other ecotypes. Since Black Sea salmon is our only endemic trout species showing typical salmon characteristics, its adaptation to the natural environmental conditions of our country for sea net cage and freshwater aquaculture is quite good.

Interplay between pond size and matrix extent drives odonate diversity patterns in a fragmented landscape

AbstractLandscape fragmentation impacts freshwater habitats and their quality, affecting aquatic insect assemblages. Adjacent terrestrial areas are important secondary habitats where amphibiotic insects mature, feed, find mates, and move to locate aquatic breeding habitats. Using a factorial design with 27 small and large ponds within small and large natural patches in an exotic tree plantation-fragmented landscape of South Africa, and odonates as model organisms, we investigated (1) how pond size/natural terrestrial patch size interaction affects odonate diversity patterns versus habitat quality variables, and (2) determined whether anisopterans and zygopterans respond differently to landscape fragmentation. Species richness was similar among ponds. However, odonate abundance was highest in large ponds regardless of natural terrestrial patch size. Zygopteran functional richness and diversity was driven by pond and natural patch size, suggesting that zygopterans are sensitive to landscape fragmentation. In contrast, anisopterans were more resilient to fragmentation and more likely to select suitable habitats following water chemistry and vegetation characteristics. Overall, large ponds were occupied by different odonate assemblages compared to small ponds, and occupancy was strongly associated with mobility traits. These findings emphasize that ponds in both small and large natural terrestrial patches have conservation value. A pondscape that represents various pond sizes is important for maintaining regional odonate diversity. Pond conservation needs to be considered in the wider terrestrial context, which host a range of important secondary habitats. Adjacent natural terrestrial habitats also connect nearby aquatic habitats, which enable insects to move across the landscape in response to natural and artificial drivers.

Assessment of the Livelihood Status of the Carp Fish Farmers in Two Unions of Puthia Upazila Under Rajshahi District, Bangladesh

Nowadays, carp culture has become an important sector in terms of nutrition supply, income generation, and increasing scope of employment in Bangladesh. The present survey was conducted to evaluate the livelihood condition of the carp fish farmers in the Shilmaria and Valukgasi unions of Puthia upazila under the Rajshahi district. The survey was done for a period of 6 months from January to June 2023. All the necessary data were collected through a structured questionnaire. Sixty farmers were included in this study. Thirty farmers were taken from the Shilmaria union and another thirty farmers were taken from the Valukgasi union. All of them were involved in carp fish farming. The average pond size of the study area was 0.35 ha. The ponds are belonging to both single (23%) and multiple ownership (77%). The majority of the carp farmers were under the age group of 41 to 50 years and had a level of education up to primary (23%). Most of the farmers were Muslims (98%) and few of them were Hindus (2%). The annual incomes of the majority of carp farmers (30%) were above Tk. 1,00,000. Sixty-seven percent of the carp farmers used semi-pucca sanitary, 22% used pucca sanitary, and 12% used kacha sanitary. Among the sample farmers, about 32% had half-building house while 14%, 11%, and 3% of the farmers had tin shed, building, and kacha house (made of mud and straw) respectively. Ninety-eight percent of the carp fish farmers availed of electricity facilities and 2% of them did not have. Most of the carp farmers (92%) used their tube well, while a few numbers of them (8%) used a neighbor's tube well for drinking water. About 60% of the carp farmers took health services from village doctors, 22% went to the upazila health complex, 8% went to the district hospital and 10% had access to the MBBS doctors in private clinics. The major constraints were the lack of scientific knowledge, the high price of fish feed, and a lack of capital for carp fish culture. So, the livelihood status of the carp fish farmer can be increased through proper training on carp fish culture and providing additional Government and Non-Government support.

Addressing the trophic status in urban ponds: An evaluation of current trophic state indexes

AbstractPonds are generally understudied. Quality problems in urban freshwaters can arise from eutrophication, and trophic status classification gives information related to their ecological situation. Ponds may strongly differ from larger lakes for which most current trophic status classification methods have been developed. This paper seeks to compare and contrast the suitability of six trophic status indexes (TSI) and OECD trophic classifications system currently used to evaluate the eutrophication level of urban ponds in the Subtropical region. The trophic status was evaluated based on total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN) and phytoplankton chlorophyll a (Chl a) in 12 ponds placed in different cities from the Pampean region (Argentina), in the warm and cold seasons. Our results demonstrate that there was no relationship between pond size (0.08–2.45 ha) and trophic status. TSIs estimated with Chl a showed significant differences between seasons and the range oligotrophic‐hypertrophic of trophism was encountered. Conversely, TSIs estimated with nutrient concentrations (TP, SRP, TN) did not. The pond's classification in trophic levels fell in the eutrophic‐hypertrophic extreme, and only considering TN/TP broadened the trophic range. No relationship was encountered between Chl a and P; however, Chl a and TN/TP were positively correlated during the warm season. Lower trophic levels regarding TSI (Chl a) were generally associated with a dense floating‐macrophyte cover. We suggest that the TSI considered should correspond to the latitudinal region in which the ponds are located. Our results indicate that it appears restrictive to consider only P contents in ponds to assess eutrophication. Under the proposed framework, the key issues for the study of pond trophic classification will be to include not only P but N concentrations and TN/TP. Also, phytoplankton Chl a concentration jointly with floating macrophytes biomass/coverage should be considered as diagnosis parameters.

Performance of phytase-treated fishmeal-free and all-plant protein diets in pond production of market sized hybrid striped bass

We determined if ideal protein (IP) fishmeal-free (FMF) or all-plant protein (PP) diets of available ingredients satisfied production needs of hybrid striped bass (HSB; Morone chrysops x M. saxatilis) grown to market size in ponds managed according to industry practices, and if phytase (Phy) superdosing (20,000 FTUs) could alleviate inorganic phosphorus supplementation. An off-the-shelf commercial feed (COM), an IP control diet containing 16% fishmeal (FM), and four IP test diets with or without phytase superdosing (FMF, FMF + Phy, PP, PP + Phy) were evaluated. Inorganic phosphorus was excluded from phytase treated diets. Hybrid striped bass (averaging 344 g/fish) were stocked (5187 fish/ha) in 4 ponds/diet (0.1 ha) and grown for 5.5 months. Most responses of the five ideal protein diets did not differ significantly (P > 0.1) from the COM. Only net fish yield, weight gain, and FCR of the PP diet were less than those of the COM diet. Fish fed FMF and FMF + Phy diets had higher fish yields, mean weights, and gains than PP and PP + Phy diets. FMF ponds had fewer than expected large (907–1134 g) and more jumbo (>1135 g) fish and FMF + Phy ponds had fewer medium (680–906 g) and more large fish. PP ponds had fewer than expected jumbo fish. The COM diet resulted in larger livers (HSI), lower muscle ratio, but less feed phosphorus added to ponds compared to the FM diet. Absence of differences for other responses confirms the FM diet is a valid proxy for the COM diet. Phytase increased energy and protein retention of the PP diet but not the FMF diet. FM can be replaced with animal and/or plant proteins exclusively without major reductions in hybrid striped bass performance. The PP diet likely requires optimization of Met and branched chain amino acid levels to improve performance. Inorganic phosphorus can be replaced by diet phytase top-coating and judicious inclusion of phytate‑phosphorus without negative impact on HSB production. Phytase superdosing of the FMF and PP diets did not improve production variables but did improve mineral retentions, more so for the PP diet. Phytase superdosing reduced feed phosphorus fed by 60% and pond phosphorus loading by 40% but requires optimization of inclusion levels and economic evaluation before recommendation.