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The present research is an attempt to screen five perennial indigenous grass species for their biochemical constituents seasonally for one year in order to determine the exact season for the harvest of the target species which will be used as feed ingredient. Among them, Cynodon dactylon has shown better result compared to other grass species and was hence incorporated as micronutrient in the formulated feed. Macrobrachium rosenbergii culture was carried out by feeding conventional and formulated feed (prepared from grass species) in tanks and ponds filled with spring water for 180 days in 2020 in the Eastern Ghats region of Koraput district, Odisha, India. Two treatments namely T1 and T2 having four replications each were supplied with commercial feed and formulated feed. Feeds were applied as per the body weight of prawns at 20% for the 1st month, 15% for the 2nd month, 10% for the 3rd and the 4th month, 5% for the 5th month and 2% till the end of the experiment. The water temperature, pH, dissolved oxygen, transparency, nitrate, phosphate, silicate, Chl a in the culture tanks and ponds were monitored fortnightly. ANOVA results between all the water parameters for both culture tanks and ponds showed significant variation (P < 0.05). The survival rate (77.0% ± 0.89%), daily growth rate (0.233 ± 0.05) g/day, specific growth rate (4.657% ± 1.04%) per day and condition index (2.638 ± 0.05) were found to be highest in prawns fed formulated feed. The feed conversion ratio varied from (2.03 ± 0.05) to (2.68 ± 0.04). Benefit cost ratio of field culture were 1.46 with yield of 702 kg/ha in conventional feed and 1.75 with yield of 950 kg/ha in formulated feed respectively. The study proved grass extracts to be efficient micronutrients for prawn feed which can be easily adopted in prawn production. [ABSTRACT FROM AUTHOR]

The oyster Striostrea prismatica is a fishery-relevant species in the eastern tropical Pacific, particularly in the Mexican Central Pacific (MCP), and little is known about its reproductive cycle. Therefore, our study analysed gametogenesis, sex ratio, sexual maturity stages, shell height at first maturity, and condition index during 2014 and 2015 in El Tizate and La Victoria in the MCP. The sex ratio was significantly biased towards males at both sites, presumably due to ontogeny or fishing pressure. The highest condition index was observed between April and May in both years, while lower values were observed from September to December. The reproductive cycle in both sites was annual, with maturity and spawning from June to August and the degradation phase in August. The condition index showed a negative correlation with temperature and chlorophyll a in both sites: as a result, the period of maximum maturity and spawning coincided with the closure of the fishery in Mexico (June-August). Females had more significant shell height at first maturity than males at both sites, possibly associated with fishing pressure. The information from this study is a significant contribution, but it is necessary to extend the studies to populations further south and further north. [ABSTRACT FROM AUTHOR]

This paper presents a maintenance prioritisation framework for Taiwan's 1268 pedestrian bridges. It aims to standardise their inspection and maintenance, as Taiwan's current bridge management specifications and manuals only apply to its highway and railway bridge infrastructure. It is designed to assess the structural safety and serviceability of six pedestrian bridge types by visual inspection. To assign weight factors to the structural safety and serviceability components of the identified bridge types, two rounds of Delphi method interviews with bridge experts were conducted. The framework is centred on a weighted average condition assessment method that integrates expert-determined weight factors with visual inspection results to calculate a condition index (PBCI). Pedestrian bridges are ranked and classified based on their PBCIs to set appropriate inspection frequency and scope, and to inform maintenance resource allocation. The application of the framework to five pedestrian bridges in Taoyuan City demonstrated its practicality and value for bridge authorities tasked with managing large inventories of pedestrian bridges. [ABSTRACT FROM AUTHOR]

The present study provides length-weight relationships (LWRs) and condition factors (Kn) estimates for ten deep-sea scorpaeniform fishes based on data consisting of new maximum size. The samples were collected from Sakthikulangara Harbour, located on the southwest coast of India, from September 2021 to December 2022. These samples were obtained as bycatch from deep-sea shrimp trawlers operating in the Arabian Sea at depths ranging from 200 to 420 m. The estimated b values ranged from 2.92 (Brachypterois serrulata) to 3.76 (Pterygotrigla arabica). The Kn ranged from 0.56 (Satyrichthys laticeps) to 1.53 (Neomerinthe erostris), with four species exhibiting Kn values higher than 1. The LWR estimates and Kn provided in this study are helpful to understand the growth characteristics of these data limited species and also to revalidate the modeled growth parameters using the Bayesian approach. [ABSTRACT FROM AUTHOR]

We investigated the annual gametogenic development of the Asiatic hard clam, Meretrix meretrix, collected from the west coast of Moheshkhali Island, Cox's Bazar, Bangladesh, by using biometry and histology through monthly sampling from July 2018 to June 2019. After biometric measurements, cross sections were cut for histology to determine the sex and gonadal maturity of the clams. Condition index (CI) showed two distinct peaks in July and December, which indicated that clams were ripe during these months, and a subsequent decrease in CI reflected spawning, which was consistent with histology. Our study revealed a biannual spawning cycle of the clams and gametogenesis starting in October and June. Spawning occurred from February to May and July to September. Maturity index (MI) showed two distinct peaks in July (3.50) and January (3.60) when most of the clams were in late developing or ripe stages. A gradual increase in temperature from annual minima in conjunction with decreasing salinity levels may trigger spawning in February, but spawning in July was initiated when salinity levels increased from annual minima. The data could be used by resource managers for the conservation of this commercial species and to time harvesting for the best quality clams without interrupting spawning activity. [ABSTRACT FROM AUTHOR]

This study provides a comparative analysis of the population dynamics and growth parameters of Mytilus galloprovincialis, based on monthly monitoring in three natural beds along the Moroccan Atlantic coast south of Agadir: Sidi R'bat, Douira, and Tifnit. Conducted over two years, from January 2018 to December 2019, the research aimed to assess the impact of mussel harvesting on their spatial distribution and ecological sustainability. Parameters were determined from size frequencies using FiSAT II software (FAO-ICLARM Stock Assessment Tools). Results showed significant variations in density, biomass, and condition index across all three sites, influenced by environmental and physicochemical factors, as well as the life cycle of the mussels. Douira exhibited the highest levels in the first year. Size class frequency distributions revealed slight differences among stations, with recruitment occurring throughout the study, peaking in winter-spring and summer. The growth rate, measured using the von Bertalanffy equation, was K = 0.5 yr-1 at all sites, with maximum asymptotic length (L∞) and growth performance index (Φ') at Tifnit, recorded at 112mm and 3.7, respectively. Mortality rates (total mortality Z, natural mortality M, fishing mortality F) and exploitation rate (E) were at their highest at Douira (Z = 2.84 yr-1, M = 0.87 yr-1, F = 3.45 yr-1, E = 0.81 yr-1), resulting in a low survival rate (S = 0.014 yr-1). The findings underscore the importance of sustainable management practices by local communities and cooperatives to ensure ecosystem sustainability and product quality. [ABSTRACT FROM AUTHOR]

Striostrea prismatica is an oyster of commercial importance present in several locations of the Eastern Tropical Pacific. The objective of this study was to evaluate the sex ratio, gametogenic cycle, maturity stages, size at first maturity (SH50) and monthly variation in the condition index of this species over the course of an annual cycle on the coast of Colima, Mexico. The oysters found in the shallow sublittoral areas near Faro de Campos were larger and heavier than those in Cuyutlan lagoon. The sex ratio was significantly shifted towards males at both sites. The gonad showed a prolonged undifferentiated stage lasting from November to April, a spawning period limited to June through October and an extended post-spawning period from August to December. SH50 was higher in females in the lagoon as well as in the shallow sublittoral. Monthly variation in surface temperature and chlorophyll a in both study areas only correlated with the condition index of populations in the shallow sublittoral and inner lagoon in the months of lowest temperatures and highest chlorophyll a. These findings provide basic information on the reproductive cycle of rock oysters that may prove useful for the development of improved harvesting practices in the study region. [ABSTRACT FROM AUTHOR]

Crassostrea (Magallana) saidii has been commercially ranched in Malaysia and consumed for more than 160 years, but it was only recently identified as a new species to science. This study was conducted to evaluate the reproductive phenology of C. (M.) saidii. Samples of 30 individual oysters were taken monthly for 15 months from the sole population at Sungai Muar estuary in Johor, Malaysia. The sex ratio was 1:1.64 (male:female) for all examined specimens, with female numbers significantly higher. Hermaphrodism was detected in 1.56% of all samples. Spawning peaks in April (2019) and November (2018 and 2019), and were positively associated with the increased rainfall upstream. Gametogenesis occurred throughout the research period with temporal variations. The highest values of maturity index (MI) were recorded in March, August and October 2019, when most oysters were in matured and maturing stages. Condition index (CI) ranged from 31.90 ± 1.25 (April 2019) to 70.03 ± 3.23 (October 2019), exhibiting two peaks (March and October 2019) and subsequently reduced in CI indicating spawning consistency with histological observations. Anthropogenic stressors such as heavy sedimentation and inland development are threatening the survival of this species. The understanding of their reproductive biology is essential to ensure the survival and sustainability of C. (M.) saidii fishery. [ABSTRACT FROM AUTHOR]

The condition of fish relates to their energy reserves, and a suite of proxies exist to approximate condition, including biochemical and morphometric indices. Biochemical indices directly measure energy stores but are expensive and sometimes lethal. Morphometrics offer several advantages, but their utility as condition proxies is debated and largely untested experimentally. Here, we manipulated the condition of yellowfin bream (Acanthopagrus australis, Günther, 1859) via food reduction to simulate the effect of poor habitat quality and calculated a variety of condition indices through time. We measured four non‐lethal morphometrics (Fulton's K, Le Cren's relative condition, width‐to‐length ratio and girth), the hepatosomatic index and a biochemical benchmark (liver lipid content). Girth and width‐to‐length ratio were reasonably well correlated with lipid content (R2 = 0.74 and 0.56, respectively). The hepatosomatic index was only weakly or uncorrelated to other indices, including lipid content (R2 = 0.35). Where precise estimates of body condition are not needed or repeat measures on the same individual are useful, non‐lethal morphometrics provide a fast, cheap and non‐lethal alternative to biochemical and lethal morphometric methods for this species. We finish by outlining how artificial intelligence‐based automation can be combined with morphometrics to further enhance ethical monitoring by eliminating the need to capture and handle fish entirely. [ABSTRACT FROM AUTHOR]

Simple Summary: The increased application of chromium compounds in several fields has resulted in elevated levels of toxic hexavalent chromium (Cr6+) in the aquatic environment, thus creating the potential for bioaccumulation of Cr6+ in the tissues as well as eliciting various toxic effects in organisms. The present study investigated the effects of Cr6+ exposure on the tissue distribution, proximate composition, and histopathology of an aquatic mollusk, periwinkle (Littorina littorea). The animals were exposed to sublethal concentrations of Cr6+ (0.42, 0.84, and 4.2 mg/L) for 30 days. Exposure to Cr6+ resulted in changes in the proximate composition and histological architecture of L. littorea. There was a low potential for bioaccumulation of Cr6+ in the tissue of L. littorea. Thus, its consumption did not pose any serious health risks to humans. The increased use of hexavalent chromium (Cr6+) in various industrial applications has contributed to its elevated levels in the environment, especially the aquatic environment. Thus, there is the potential for accumulation of Cr6+ in the tissues of aquatic organisms and consequent toxic effects. The toxic effects of Cr6+ in aquatic organisms have been widely reported; however, little is known about the patterns of tissue accumulation of Cr6+ and its toxicity in aquatic mollusks. Thus, the present study investigated the effects of Cr6+ exposure on the tissue distribution, proximate composition, and histopathology of an aquatic mollusk, periwinkle (Littorina littorea). The animals were exposed to sublethal concentrations of Cr6+ (0.42, 0.84, and 4.2 mg/L) for 30 days, after which the condition index, tissue accumulation, proximate composition, and histopathological effects were determined. The control animals were maintained in a medium that did not contain Cr6+ (0 mg/L). The condition index did not differ significantly among the groups. The levels of Cr6+ in the tissues differed significantly among the different tissue types while there was no significant effect of the exposure concentration, except in the foot tissue. The proximate parameters (protein, carbohydrates, lipid, crude fiber, and moisture contents) differed significantly among the groups. The protein contents of the exposed animals were significantly lower than those of the control animals and the histological architecture of the major organs was altered in the chromium-exposed animals. The findings from this study indicate a low potential of L. littorea to bioaccumulate Cr6+ in its tissues at the low exposure concentrations tested in this study; as such, its consumption may not pose any serious health risks to humans. However, changes in the proximate composition and histological architecture of the exposed L. littorea show that Cr6+ is potentially toxic to periwinkles. [ABSTRACT FROM AUTHOR]

The reproductive biology of Mactra stultorum from the Gulf of Gabes was investigated monthly during a one-year period (2017). This study is the first study examining its reproductive biology during one-year in the south of Tunisia. The overall samples presented a balanced sex ratio, with males dominating among smaller individuals (< 22 mm) and females predominating in larger size classes (> 34 mm). The obtained total sex ratio (F:M) was equal to 1.03:1. The size at first maturity (SL50%) was 20.43 and 22.10 mm for males and females, respectively. The seasonal variations assessed through macro- and microscopic characteristics in the gonads of both sexes indicated a clearly defined annual reproductive cycle with a principal spawning peak during summer and a resting period during December and January. The reproduction of M. stultorum was strongly influenced by fluctuations in the seawater temperature, as reflected through the temporal variation in the gonadal cycle, condition index (CI) and tissue weight rate (TiWR). If managed properly, M. stultorum is expected to meet the domestic market demand through artisanal fishery. The adoption and implementation of rules, such as limiting the size of clams, is required to protect this new exploitable fishery resource. [ABSTRACT FROM AUTHOR]

The reproductive performance knowledge of economically important bivalves is essential to establish better shellfishery management measures and aquaculture programs. The reproductive cycle, as well as the nutrient storage and utilization of two Portuguese Cerastoderma edule populations from Óbidos and Ria Formosa lagoons were characterized by evaluating gonadal development stages, gonadal and condition indexes, as well as glycogen and total lipid content, over several consecutive years. The relationship between reproduction and environmental parameters (sea surface temperature and chlorophyll a) was assessed. The reproductive cycle of both populations of C. edule followed a clear seasonal pattern. The onset of gametogenesis took place in early autumn for both populations, and its evolution coincided with a temperature decrease which progressed throughout the winter. The mature stage was reached in spring, followed by a spawning period during spring and summer, triggered by a rise in temperature. After spawning, both populations progressed to a prolonged inactive stage. The condition index reflected the accumulation and utilization of glycogen, which was considerably higher in the Óbidos population. However, no relationships were found in the reproductive cycle of the species. Total lipids remained similar not only during the gametogenesis period, but also during the spawning period, which may be related to successive and simultaneous gamete production and release. [ABSTRACT FROM AUTHOR]

The average values of the seasonal flesh biochemical composition (%) of the pearl oyster Pinctada imbricata radiata originated form 2 sampling sites, the gulfs of Evoikos (E) and Saronikos (S) in the Western Aegean Sea, showed that is rich in proteins (64.00 ± 1.86 -(E), 64.67 ± 2.95-(S)) with low fat content (10.96 ± 1.04-(E), 11.86 ± 1.13-(S)) and carbohydrates (13.29 ± 2.48- (E), 9.94 ± 4.32 (S)). The condition index ranged from 26.16% ± 5.04 in the autumn in (E), to 44.73% ± 7.50 in the summer in (S). The meat yield varied from 20.49% ± 3.20% in the summer in (E) to 30.73% ± 3.47% in the summer in (S). Both results demonstrate the high nutritional profile of the pearl oyster, supporting its suitability as a potential new Mediterranean seafood source for human consumption. [ABSTRACT FROM AUTHOR]

Pacific Northwest Indigenous communities historically managed terrestrial and marine environments to increase the productivity and access of traditional foods. Sea gardens, also called clam gardens, were an Indigenous aquaculture method that increased traditional food habitat for targeted food species such as bivalves. This study utilized fatty acid biomarker analysis alongside stable isotopic analysis with bivalve condition indices of traditionally harvested littleneck clams (Leukoma staminea) to investigate dietary and trophic differences between sea gardens and non-walled beaches in Kanish Bay, Quadra Island, British Columbia. We utilized non-metric multidimensional scaling, distance-based redundancy analysis (db-RDA), and Bayesian three-source isotopic mixing models to examine impacts of environmental drivers on bivalve dietary composition and condition at four sea garden sites and four non-walled sites. Bivalve tissue saturated fatty acids (sum SFAs) showed statistical significance (Mann-Whitney U-Test, W = 3447, P = 0.01), indicating that sea garden clams (x2 = 34.96; SD = 7.56) had higher mean relative percent areas of SFAs compared to nonwalled sites (x2 = 31.76; 7.71). Bivalve monounsaturated fatty acids (MUFAs) showed statistical significance (Mann-Whitney U-Test, W = 1202, P = 0.01, a = 0.05), indicating sea garden clams (x2 = 3.48; SD = 3.78) had lower mean relative percent areas of MUFAs compared to those in non-walled sites (x2 = 6.97; SD = 5.90). Sea garden bivalves were found to feed at a higher trophic level, with a slimmer dietary range, compared to non-walled clams. Both dietary marker differences and differentiated trophic positioning suggest decreased physiological stressors impacting feeding of bivalves, differences in dietary particulate intake, or a combination of both occurring at sea garden sites compared to non-walled sites. Correlations within a db-RDA indicate that bivalves with high body condition indices at sea garden sites were benefiting from decreased stress related to favorable salinity and oxygen parameters, which positively impacted bivalve feeding and respiration. Observed trophic niche differences and fatty acid differences would also be explained by this suggested mechanism. We conclude that partial trophic shifts and fatty acid changes of sea garden L. staminea bivalves are consistent with stress-alleviated bivalve responses, and match correlated variables in our db-RDA. Trophic niche differences and fatty acid shifts between sea gardens and non-walled sites should be further explored by using a quantitative method to identify sea gardens from nonwalled sites in addition to established field verification methods. [ABSTRACT FROM AUTHOR]

The relevance of the study is related to the need to determine the current state of windbreaks as a component of the forest-agrarian landscape of a particular region. The purpose of the study is to conduct a comprehensive assessment of windbreaks. During the study, data from remote sensing of the Earth using satellite imagery was utilised, which allowed for determining field parameters, the placement of the windbreak system, and their characteristics. Forest inventory works were conducted using commonly accepted methods in forest mensuration, with adjustments made specifically for windbreaks. The quality class of windbreaks was determined based on the percentage of healthy trees out of the total number, and the sanitary condition index was calculated according to established categories. The analysis of the obtained data clearly shows a decline in the quality sequence of common oak from 9 to 3 units within the plantations. The windbreaks were created using the method of oak nest planting, with oak nests placed at a spacing of 5.0*3.0 m and a total windbreak width of 15.0 m. Two additional rows of companion trees were introduced in the wide 5-metre alleys, and companion and shrub species were added within the nest rows. The analysis of the characteristics of windbreaks showed that they have protective heights ranging from 19.6 m to 23.4 m and provide reliable protection for adjacent agricultural fields. Based on the range of effective protective effects of windbreaks, it can be noted that the calculated indicators provide protection with a reliable safety margin of up to 17%. If there is a need to create new windbreaks using the nest planting method in the future, a more efficient scheme is proposed, which involves placing companion tree species in the outer rows to prevent the crowns of the inner rows from spreading towards the field. As a result of the obtained findings, it became possible to conduct a comprehensive expert assessment of the state of windbreaks according to the following criteria: forestry and inventory parameters, meliorative properties, and the sanitary condition index [ABSTRACT FROM AUTHOR]

Oysters are a foundational part of their ecosystem and research has shown they are negatively impacted by exposure to microplastics (MPs). High MP levels have been documented in waters surrounding oyster reefs, and as filter feeders, oysters can ingest MPs along with their food. Here, we determined MPs (>30 µm) in oysters (Crassostrea virginica) from ten sites across the Mississippi Gulf Coast. Further, a subset of these samples was dissected to quantify MPs within specific tissues. Average concentrations ranged from 30.7± 11.5 to 4.7 ± 0.25 putative MPs/g wet weight (ww) of whole tissue, with sites inside bays near population centers displaying higher levels of MPs than those exposed directly to the Gulf. Mantle, gill, and adductor muscle tissues had similar concentrations of putative MPs (15.9 ± 13.4, 11.5 ± 8.6 and 12.8 ± 6.7 MPs/g, respectively), whereas digestive system tissues had lower concentrations (6.8 ± 6.1 MPs/g of tissue). This suggests that most MPs in an oyster likely adhere to external tissues and are not actually ingested. Most of the MPs retained were in the smallest size fraction of 30‐90 µm (80%), followed by 125‐250 µm (9%), 90‐125 µm (8%), and >250 µm (3%). Analysis of samples from Biloxi Bay by µ‐FTIR to assess MP composition shows that polyurethane, polyethylene, and polyamide are common, but additional analyses are needed to fully characterize the MP profile across sites. Overall, this work provides much‐needed empirical data on the abundances and sizes of MPs in oysters from the Mississippi Sound, as well as the tissues where they reside. [ABSTRACT FROM AUTHOR]

In this paper, a new D-distance factor is proposed to determine the failure probability and to prioritize maintenance actions of power circuit breakers in high-voltage substations. The D-distance factor is calculated by using the condition index and renovation index of a high-voltage circuit breaker (HVCB). To facilitate effective decision-making on maintenance with a simple method and less computational effort, the proposed model incorporates the weighting–scoring method (WSM) and analytical hierarchy process (AHP) with the various diagnostic methods for condition index assessments as well as the operation requirements of HVCBs for renovation index assessments. Many significant parameters from circuit breaker testing, such as insulation resistance, contact resistance, contact timing, SF6 gas measurements, gas leakage rate, visual inspection, etc., have been considered for condition index determination. In addition to these, other significant parameters, such as age of the circuit breaker, age of the interrupter and mechanism, number of fault current interruptions, actual load current to rated current ratio, actual short circuit current to rated interrupting current ratio, maintenance ability, spare parts availability, maintenance expertise level, etc., are also considered for renovation index determination. To validate the proposed model, the practical test data of twenty 115 kV HVCBs in various substations of a distribution utility in Thailand were utilized and tested. By analyzing the actual condition and operation requirement of the circuit breaker, the output, as the condition index and renovation index using the proposed method, is discussed with HVCB experts in the utility to adjust the scores and weights of all criteria to obtain the most accurate and reliable model. The results show that the D-distance technique measured from the risk matrix, which is defined as the failure probability, can be used to rank the maintenance schedule from urgent to normal maintenance tasks. In addition, various failure probabilities in the risk matrix of the circuit breaker can be used to determine the appropriate maintenance strategies for the power circuit breaker in each group. Finally, the proposed method could help the utility managers and maintenance engineers manage the maintenance planning effectively and easily for thousands of HVCBs in the grid, and it can be further applied with other high-voltage equipment in both transmission and distribution systems to facilitate the maintenance activities according to available costs and human resources. [ABSTRACT FROM AUTHOR]

In this study, we investigate whether the Tukey M robust regression method provides a solution for the data sets suffering from multicollinearity problem. It is observed that high values of variance inflation factors (VIF) which is a sign of the multiple linear link among the explanatory variables, cannot be controlled by the robust methods which work through the residual values. The reason for this fact is that multicollinearity and high values of VIF which is a result of multicollinearity do not produce extreme residuals. For this reason, the robust methods cannot provide a solution for the high VIF problem. This fact is shown by an extensive simulation study. In the simulation study, the explanatory variables were derived from trivariate normal distribution for three different correlation values. In this study, we also used two real-life data examples and we observed that the results support the findings of the simulation study. For all these reasons, we can conclude that specialized methods should be utilized in the case of multicollinearity. [ABSTRACT FROM AUTHOR]

Grow-out methods like the raft and longline have been utilized by various countries in growing green mussel, Perna viridis. In the Philippines, the stake method using bamboo poles is still widely used, which is believed to cause siltation that negatively affects green mussel production. In this study, the feasibility of raft and longline methods was determined based on mussel growth and the condition index (CI). Environmental conditions in Cañas Bay, Iloilo were also presented. Results showed that there was no significant difference in mussel growth except for final weight, where mussels in the raft were found to be significantly heavier than those in the longline. Meanwhile, the CI of mussels did not significantly differ between the two methods. Physico-chemical parameters of the water in Cañas Bay were found to be suitable for growing green mussels. Phytoplankton was composed of diatoms (86%), dinoflagellates (6%), green algae (5%), and blue-green algae (3%). This study showed the feasibility of using suspended methods like raft and longline in areas where environmental conditions favor mussel growth. [ABSTRACT FROM AUTHOR]

Complex coastal currents control early-stage larval dispersal from intertidal populations, and late-stage settlement patterns, but are often poorly resolved in larval dispersal models. Generally, there is high uncertainty in the timing of larval spawning, which markedly affects larval dispersal. In this study, we describe the physical parameters that induce spawning events in the blue mussel, Mytilus edulis, using a variation of the Condition Index (which relates the mass of meat to the mass of the shell) as a proxy. We developed a high-resolution Eulerian coastal hydrodynamic model, coupled with a Lagrangian particle tracking model, to quantify the potential dispersal of early-stage mussel larvae based on differing spawning dates obtained from field data. Our results showed that (1) the timings of larval spawning cannot be explained solely by 'thermal shocks' in the sea or air temperatures (i.e. fluctuations in temperature causing stress); (2) larger spawning events generally occurred during neap tides; (3) the simulated larval dispersal was largely but not always predicted by averaged current pathways (calculated over two weeks period); and (4) simulated self-recruitment was low at sites associated with strong tidal currents. These results have important implications for shellfisheries stock management and sustainability. Specific to this study, simulated mussels from shellfishery beds off North Wales dispersed more than 25 km in one week and so could feasibly contribute to the wider population throughout the northern part of the Irish Sea. [ABSTRACT FROM AUTHOR]

The widespread occurrence of plastic has become a significant problem in the natural environment and may give rise to a range of deleterious impacts in biota, particularly where plastic particles overlap in size with that of the particles that are naturally ingested by filter-feeders. In this context, the effects of two particle sizes (10 μm and 50 μm) of polymethylmethacrylate (PMMA) on ecologically and commercially significant mussel Mytilus galloprovincialis have been investigated. Mussel health status was evaluated by measuring the condition index and stress-on-stress test during and after 72 h exposure to PMMA microparticles in the 0.1–10 mg L−1 concentration range. The decreased condition and fitness indices in the exposed mussels pointed to significant physiological effects at the entire organism level. The 10 μm and 50 μm PMMA particles were noted to rapidly increase the total haemocytes count in haemolymph, and significantly reduce cell viability at higher concentrations of both particle sizes. The results also indicated a significant increase in levels of vacuolised haemocytes as a result of PMMA exposure. While both microparticles were detected in the haemolymph, only the 10 μm PMMA was observed in the gill tissue and digestive gland by histological cryosections, indicating their rapid uptake, transport, and accumulation in tissue. Lack of accumulation of 50 μm microparticles in tissue may be related to a combination of chemical identity and size considerations, enabling more efficient depuration of microparticles in pseudofaeces. The PMMA particles did not induce significant changes in activity of a range of enzymes involved in neurotransmission and responses to oxidative stress. [ABSTRACT FROM AUTHOR]

Native to the Gulf of Mexico, Gulf wedge clam (Rangia cuneata) has been successfully invading Baltic Sea since first introduction with ballast waters in 2010. In this study, we report new occurrence sites in the Pomeranian Bay and in the brackish water of the Szczecin Lagoon. We aimed to describe the structure and stability of the new population of Gulf wedge clam using ecological indicators (i.e. condition index, length-at-age) and a molecular approach targeting first cytochrome oxidase subunit (COX1) fragments. The study showed an age structure dominated by adult clams (aged 4+), rather than the often reported juveniles. We found that the condition of the R. cuneata population in the Pomeranian Bay is characteristic of the expansion model after bottleneck. Genetic analyses indicated low nucleotide (π = 0.00387 ± 0.00012) and haplotype (h = 0.79 ± 0.018) diversity. A haplotype network inferred by a median-joining method showed lack of haplotype H6 (Chesapeake Bay, NW Atlantic) and numerous individuals with haplotype H1 (Gulf of Mexico). Demographic parameters (non-significant Tajima's D = 2.058, Fu's Fs = 2.298, Fu and Li's D* = 1.195, and significant Fu and Li's F test = 1.757) suggested that the population underwent a moderate population bottleneck, while analysis of mismatch distribution showed a bimodal shape which may imply population admixture as a consequence of "allelic surfing". Moreover, we concluded that R. cuneata has successfully invaded the basin of the LNG terminal, although our study proved non-linear growth of this species. [ABSTRACT FROM AUTHOR]

Along the northern Mid-Atlantic Ridge (nMAR), in habitats under moderate (<10 °C) hydrothermal influence on the Snake Pit vent field (SP), large assemblages dominated by Bathymodiolin mussels remain poorly characterised, contrary to those in warmer habitats dominated by gastropods and alvinocaridid shrimps that were recently described. In this study, we assessed and compared the population structure, biomass, diversity and trophic interactions of two Bathymodiolus puteoserpentis assemblages and their associated fauna at SP. Three sampling units distanced by 30 cm were sampled in 2014 during the BICOSE cruise at the top of the Moose site (''Elan'' site), while few meters further down three others, distanced by ∼1 m were obtained in 2018 during the BICOSE 2 cruise at the edifice's base. We observed a micro-scale heterogeneity between these six sampling units partially explained by temperature variations, proximity to hydrothermal fluids and position on the edifice. Meiofauna dominate or co-dominate most of the sampling units, with higher densities at the base of the edifice. In terms of macrofauna, high abundance of Pseudorimula midatlantica gastropods was observed at the top of the vent edifice, while numerous Ophioctenella acies ophiuroids were found at the base. Contrary to what was expected, the apparent health and abundance of mussels seems to indicate a current climax stage of the community. However, the modification of B. puteoserpentis isotopic signatures, low number of juveniles decreasing over the two years and observations made during several French cruises in the study area raise questions about the fate of the B. puteoserpentis population over time, which remains to be verified in a future sampling campaign. • Assemblage heterogeneity at different scales linked to fluid proximity & location. • Meiofaunal groups dominated. Macrofaunal disparity between top and base of edifice. • Low number of mussel juveniles over time questions the future of the population. [ABSTRACT FROM AUTHOR]

Corbicula fluminea is a known aquatic invasive species responsible for several ecological and economic impacts. In Portugal, it is found in all major watersheds, although to varying degrees of invasion (regarding density, biomass and spatial distribution). The aim of this study was to evaluate the spatio-temporal differences in condition indices (CIs) and biochemical composition (proteins, lipids and energy) of individuals collected in Lima (low invasion) and Minho (high invasion) Rivers, as well as the effects of intra-specific competition (densities: 150, 500, 1000 individuals/m2) on the CIs of C. fluminea. CIs and biochemical composition varied between rivers and over time, with populations in Lima and Minho showing different patterns. Corbicula fluminea in Lima River had higher CIs and lower densities with more individuals of larger size, while individuals in Minho River had lower CIs and high densities with a more uniform size distribution. The intra-specific competition experiment showed that the optimum of C. fluminea was reached at 500 individuals/m2 density, possibly related to the species ability of enrich sediments with organic matter, leading to a positive feedback on phytoplankton and/or microbial communities. This study improves the understanding of the ecophysiological conditions of C. fluminea populations, a topic neglected in previous studies. [ABSTRACT FROM AUTHOR]

In the mobile sedimentary environment of San Antonio Bay (northern Patagonia), where hard substrate is scarce, the mussel Brachidontes rodriguezii dominates the intertidal zone, there being covered by the introduced epibiotic barnacle Balanus glandula. The aim of this study was to evaluate the distribution and the recruitment of B. glandula on different non‐living substrates (cobbles, biogenic debris) and on live‐mussel shells and to assess the effect of the epibiotic interaction on the condition index and the attachment strength of B. rodriguezii. Field samplings revealed that adult barnacles mainly fouled live mussels, with the main differences in biomass being between the high and mid‐intertidal. These differences in barnacle biomass between heights and substrates were greater in spring and autumn than in winter and summer. To assess the recruitment of barnacles, we performed a field experiment manipulating living and non‐living substrates. We found no differences in the density of barnacles recruitment; thus, the barnacle distribution on different substrates throughout the intertidal would vary solely according to the settling substrates available. The relationship between epibiosis and the condition index exhibited no pattern. Furthermore, the experimental manipulation of epibiosis (i.e., removing epibionts or adding epibionts mimics) did not affect the condition of the mussels. Finally, the attachment strength of mussels with epibionts was up to fivefold greater than that of clean mussels. In a system with high tidal hydrodynamic energy, epibiosis is thus seen to stimulate a greater byssal production in mussels for the prevention of detachment. [ABSTRACT FROM AUTHOR]

Local environmental conditions can have strong effects on ecophysiological responses in bivalve molluscs. Molluscs must allocate the energetic resources acquired in their habitats to survival and fitness. In this study, we investigated the spatial and temporal patterns of response in relation to byssus strength and soft tissue weight during the maximum growth stage in the subtidal mussel Mytilus galloprovincialis between March and July 2015 in the Ría de Arousa (NW Spain). Mussels growing in high‐energy environments secreted stronger byssus than those inhabiting low‐energy sites. The integrated values of wave height and food availability for the previous 15 days showed a positive relationship explaining 45% and 9% of total variability in tenacity of the byssus threads. Differences in condition index were greatest between the northern (highest values) and southern sites at the mouth of the ria owing to differences in food availability. Despite similar hydrodynamic energy values, the high food availability in the exposed northern zones supplied sufficient energetic resources for both strong byssus secretion and high CI. Despite lower food availability, high CI values were also reached in mussels in the innermost, sheltered sites, because of the low need for survival with strong attachment. The condition index was positively correlated with temperature and food availability integrated during 45 previous days prior explained a 57% and 13% of total variance, respectively, while wave height explained 2% but with an inverse relationship. Environmental differences between the geographical zones of the estuary modulated byssus secretion functionality affecting the soft tissues status of mussels. [ABSTRACT FROM AUTHOR]

The peppery furrow shell Scrobicularia plana is a commercial valuable bivalve in the east Atlantic and Mediterranean Sea. To ensure the sustainability of this resource and implement efficient management strategies, it is essential to understand the life history traits of the species, such as growth, reproduction, and size at first maturity. These features were investigated in the southern range of the species' European distribution, specifically in Ria de Aveiro (Portugal), and compared to other geographical areas. At Ria de Aveiro S. plana spawns from June to October, with a peak in August/September, aligning with the typical reproductive pattern of mid latitude European populations. The condition index is lowest in March and highest in May just before spawning. Sexual maturity (L 50 = 27 mm SL) is attained at approximately 1 year of age, enabling offspring to reproduce in the subsequent spawning season. In this study, the overall sex ratio did not differ significantly from 1:1. Hermaphroditism (ovotestis) was detected in one specimen, representing 0.3% of the total examined males. Shell rings are formed annually during growth cessation in fall/winter and become conspicuous when growth resumes in March. The growth equation parameters, estimated from surface shell ring analysis and internal shell microgrowth bands, were: Lt = 58.1[1 - e−0.46(t −0.09)]; Lt = 54.7[1 - e−0.53(t −0.30)], respectively. Values for K and L ∞ are among the highest recorded for the species, highlighting the growth performance of S. plana in the Ria de Aveiro and its potential for commercial exploitation. An analysis of morphometric relationships between shell length, height, and width was performed to optimize the harvesting process of S. plana. Management measures are proposed for the fishery of S. plana in Ria de Aveiro, based on the species' biological traits. [Display omitted] • Reproductive biology of Scrobicularia plana is described. • Condition index exhibited a seasonal pattern linked to the reproductive cycle. • Fast growth and rapid maturity allow first-year reproduction. • A minimum conservation reference size of 27 mm SL can enhance sustainable exploitation. • A closed fishing season between August and November should be enforced. [ABSTRACT FROM AUTHOR]

Blue mussels, Mytilus galloprovincialis, are a widespread and ecologically important species in New Zealand coastal ecosystems, yet, there is limited information on the seasonality and variability in reproduction among populations. The reproductive cycle of M. galloprovincialis was studied monthly over 1-year in two southern New Zealand populations (Aramoana (45.7787°S, 170.7037°E) and Timaru (44.3905°S, 171.2498°E)). Tissue indices were determined, and gonads examined histologically. At both sites, males and females displayed synchronous changes in condition indices and gonad indices, with both indices generally greater in the Timaru population than in the Aramoana population. Both sampling sites presented with comparable seasonality of reproduction with spawning over spring and summer months (September to February). Gametogenic development occurred over the autumn and early-winter period (March to August). Spatial differences in reproduction coincided with differences in phytoplankton food abundance (greater in Timaru), while there were only small differences in sea temperatures between sites. This study indicates the likelihood of spatial variation in reproductive biology between M. galloprovincialis populations, even across small spatial scales (<200 km). [ABSTRACT FROM AUTHOR]

Ecological impacts caused by invasive alien species can be severe but may vary depending upon environmental conditions. Many European populations of the native mussel, Mytilus edulis, have been invaded by the Pacific oyster, Crassostrea (Magallana) gigas. Although widespread invasions have occurred, interactions between M. edulis and C. gigas have largely been investigated with regards to competition for space and food as well as effects on species assemblages. Experimental investigation of competitive interactions on physiological responses of the two species requires further exploration. To this end, we used a 12-month field manipulation experiment to examine growth rates, mortality and condition indices of the two species occurring in monospecific and heterospecific groups. Growth rates and mortality of both species were similar in monospecific and heterospecific groups, whereas condition indices were significantly reduced for both species in heterospecific groups. Growth rates and condition indices also differed amongst experimental sites, potentially due to differing water motion. Shell weight-length relationships did not explain the observed differences in condition for either species. We show that coexistence between the two species may occur but could be detrimental for both species. We also provide a preliminary viewpoint that water motion can mediate competitive interactions between these species. [ABSTRACT FROM AUTHOR]

The study was carried out with a four-summer-old male Siberian sturgeon, reared in net cages, installed in a large warm reservoir in Bulgaria. Two groups of fish were formed for the purpose of the analysis made at the end of the vegetation period – with lower (2823.0 ± 126.04 g) and higher (4273.2 ± 110.29 g) live weight. Fish of the first group had significantly lower weight of the carcass, fillet, total insides, gonads, liver, fins and tail, head without gills, gills, swim bladder and chord, compared to fish with higher live weight. The two groups did not differ significantly in the weight of heart, spleen and bone plates. In the frames of the experiment, the eviscerated weight and the relative share of carcass in the total body weight was 86.40-86.86% and 57.07-61.52%, respectively. The relative share of the whole fillet with skin in the body and in the carcass was 45.61-50.75% and 78.37-82.54%, respectively. All the parameters characterizing the slaughter value showed better results in fish with higher live weight, but the difference between the groups was significant only in the relative share of the fillet in the carcass (4.16%, p<0.001). All the indices of fish condition were higher in the group with higher live weight, the difference being significant in the condition index IC (p<0.01) and in the modified Fulton’s coefficient ICR (p<0.05). Referring to the interior indices, no clear dependencies were established related to fish live weight. The viscerosomatic and cardiosomatic indices were higher in the smaller fishes, and the hepatosomatic, spleen-somatic and gonadosomatic indices – in the heavier representatives, the difference being significant only in the latter index (p<0.05). [ABSTRACT FROM AUTHOR]

Condition index (CI) is a widely used parameter in ecological and physiological studies. For molluscan bivalves, no universal consensus exists for CI calculation. A literature review revealed that a total of 19 methods have been used for CI calculation in molluscan bivalves. To evaluate the CI calculation in northern quahogs Mercenaria mercenaria (also called hard clams), market‐sized clams at 12–14 months old (n = 300 from three populations) were collected for gravimetrical and volumetric measurements. Significant correlations were identified among body sizes (body length, height and width), body weights (total weight, wet meat weight, dry meat weight, wet shell weight, dry shell weight) and body volume (p <.0001, R values ≥.800). Referencing previously used CI equations for molluscan bivalves, a total of 18 equations were evaluated the suitability, considering non‐lethal measurements, for northern quahogs through correlation analysis of the CIs from different equations. With equations constructed as the percentages of dry or wet meat weight out of total weight, dry shell weight, dry shell plus meat weight, body volume, body length*height*width, shell length or cubic of shell length, CIs were significantly correlated, meaning that these equations were exchangeable. Specifically, three equations with non‐lethal measurements (percentages of total body weight out of total body volume, body length*height*width or cubic of body length) were evaluated effective. Overall, this publication provided a review for CI calculations in molluscan bivalves and evaluated the CI equations for northern quahogs. [ABSTRACT FROM AUTHOR]

The cockle Cerastoderma glaucum represents a significant element of the benthic community in Lake Qarun, Egypt. The population of this species has severely declined in the lake. For stock position assessment, cockles were collected in the winter of 2008 and 2018. The body size (length-frequency) distributions considerably varied among the collections. A single peak at 14 mm was present in 2008, and two peaks appeared ten years later (one at 13mm and another at 19 mm). The total weight, shell weight and flesh weight of individuals collected in 2008 exhibited isometric increase with shell length (SL). For samples collected in 2018, flesh weight increase was slower than shell length, indicating negative allometric growth. When 50% of the population achieved maturity (SM50), their sizes were 7.7 and 7.4 mm of SL for 2008 and 2018 collections, respectively, consistent with the sexual maturity being related to size rather than age. The overall sex ratios did not significantly differ from unity (1:1). The results of this study suggest that the species is sensitive to salinity changes and water pollution, with larger individuals being more resistant than the smaller ones. This may have implications for species' long-term reproduction and density. [ABSTRACT FROM AUTHOR]

Females of many species select mates based on important morphological and performance traits. This behaviour likely facilitates reproductive success thus exhibiting sexual selection. Most such studies have evaluated a single morphological variable, and only a minority of them studies the effects of behaviour and performance (functional capacity: Irschick et al., Evolutionary Ecology Research, 10, 177–196, 2008) at all.This study compares male morphological and performance traits differing in three variables that may correlate with fitness: condition index, flight ascent speed and resistance to torpor in relation to male mating success in the parasitoid wasp species Alabagrus texanus (Braconidae), a species where males swarm about emerging virgin females that display both choosy and non‐choosy behavioural phenotypes.Males that successfully mated with choosy females exhibited higher condition indices and somewhat stronger resistance to torpor than other males. Conversely, males that mated with non‐choosy females did not differ in any trait from other males we measured. Early‐arriving males did not have higher condition indices or greater mating success than other males.Thus, both morphological and performance traits contributed to male success, which acted through female choice, indicating a role for sexual selection. Patterns of choice further differed among females, independent of male traits. [ABSTRACT FROM AUTHOR]

Various drought indices are developed to monitor drought conditions. Each drought index applies to specific environments given its own characteristics. This article aims to compare the drought conditions of continental China detected by remote sensing. We compare diverse types of remote sensing-based indices for studying drought situation in 2017. The Station-based precipitation data with different scales are used to evaluate drought phenomena. The drought indices compared in this article include the precipitation condition index (PCI) derived from tropical rainfall measuring mission data, vegetation condition index (VCI), temperature condition index (TCI) derived from moderate-resolution imaging spectra-radiometer (MODIS) data, and other integrated drought indices, which combine VCI, TCI, and PCI. Vegetation health index (VHI), scaled drought condition index (SDCI), and synthesized drought index (SDI) constitute the integrated drought indices. The results indicate that numerous indices have different applicability across continental China. VHI has the optimal correlation with short-term and long-term precipitation. The SDI, SDCI, VCI, TCI, and temperature–vegetation dryness index (TVDI) are also reliable for monitoring drought conditions and are more suitable for long-term than short-term precipitation. Furthermore, combined indices (VHI, SDI, and SDCI) perform better than single drought indices (PCI, TCI, and VCI). VHI, SDI, and SDCI did not show good consistency in croplands when monitoring agricultural drought. [ABSTRACT FROM AUTHOR]

Although the false mussel Mytilopsis sallei Recluz, 1849 is recognised as an aggressive invasive species, its populations in several estuaries in Thailand are restricted to small areas. A salinity gradient is a major characteristic of its habitat, hence the effect of various salinity levels (0–40 ppt) on the mortality of larvae, juveniles and adults of M. sallei was investigated. Condition Indices of adults reared at different salinity levels for two months were measured. Spatial and temporal variations of salinity and false mussel abundance in a canal with a salinity gradient were also monitored. After an acute (48 h) test, survival of larvae was highest at salinity levels of 12.5 and 16.25 ppt and decreased at lower and higher levels. Juveniles survived at all salinity levels, but most adults died in the first 24 h at a salinity of 40 ppt, while condition indices were lowest at salinity levels of 30 and 35 ppt. In the field survey, highest false mussel abundance was consistently found at the middle part of the canal with mid-range salinity. The results suggested that salinity is a determinant of survival in M. sallei larvae and potentially regulates the dispersal success of false mussels. However, the importance of salinity was marginal in the later stages of its life history. [ABSTRACT FROM AUTHOR]

The national transport matrix is represented by predominance in the use of highways, which receive investments from the population in the form of taxes or toll rates. Thus, their condition and care is related to the development of the country and directly influences the lives of Brazilians. In the present study evaluated stretches of highways managed by public bodies and companies in Rio Grande do Sul state with the objective of identifying the quality obtained through different forms of management. The composition of Highway Condition Index - IC indicates that the presence of the toll does not result, by itself, in better condition states, as well as the degree of local urbanization can also be relevant factor in these highways. Despite the demands of large centers, quality is required in all road modalities and requires a careful inspection of the results of investments. [ABSTRACT FROM AUTHOR]

Global warming and ocean acidification influence marine calcifying organisms, particularly those with external shells. Among these, mussels may compensate for environmental changes by phenotypic plasticity, but this may entail trade-offs between shell deposition, growth and reproduction. We assessed main and interactive effects of pH and temperature on four mussel species on the west coast of South Africa (33°48′ S, 18°27′ E) in October 2012 by comparing shell dissolution, shell growth, shell breaking force and condition index of two native species, the ribbed mussel Aulacomya atra and the black mussel Choromytilus meridionalis, and two aliens, the Mediterranean mussel Mytilus galloprovincialis and the bisexual mussel Semimytilus algosus. Live mussels and dead shells were exposed for 42 days to seawater of pH 7.5 or 8.0, at 14 °C or 20 °C. Low pH, high temperature and their combination increased shell dissolution of the two aliens but their growth rates and condition indices remained unchanged. Aulacomya atra also experienced greater shell dissolution at a low pH and high temperature, but grew faster in low-pH treatments. For C. meridionalis, shell dissolution was unaffected by pH or temperature; it also grew faster in low-pH treatments, but had a lower condition index in the higher temperature treatment. Shell strength was not determined by thickness alone. In most respects, all four species proved to be robust to short-term reduction of pH and elevation of temperature, but the native species compensated for greater shell dissolution at low pH by increasing growth rate, whereas the aliens did not, so their invasive success cannot be ascribed to benefits accruing from climate change. [ABSTRACT FROM AUTHOR]

We investigated the annual gametogenic phenology of the freshwater pearl mussel, Lamellidens marginalis (Lamarck, 1819), collected from a lentic habitat at Mymensingh, Bangladesh, using biometry and histology through monthly sampling from August 2015 to July 2016. After biometric measurements, thin slices of dorso-ventral sections were cut from the middle of the mussels for histology to determine sex and level of gonadal maturation. The condition index (CI) ranged from 0.64 (March) to 0.99 (January) over the study period. The CI peaked three times (January, April and July) indicating that the mussels were ripe during these months and subsequent decreases in CI indicated spawning, which was consistent with histology. Both males and females exhibited similar patterns in terms of gonadal development, maturation and spawning activity. It was confirmed that natural populations of L. marginalis spawn throughout the year with remarkable temporal variations, except during December when the surface water temperature reaches annual minima (16.5°C). Highest spawning activity of L. marginalis was noted during February–March, May and July–November. The data obtained in the present study could be useful for the conservation managers of this commercial species by allowing harvesting of better quality mussels to be timed without interrupting major spawning activity. [ABSTRACT FROM AUTHOR]

Morphometric parameters and their indices are central to characterization, selection and genetic improvement of farm animals. The present study was conducted to fix multicollinearity among predictors and to fit optimum regression model for prediction of 14-week body weight of 150 un-sexed Sudani ducks from early age (0, 2, 4 and 6 weeks of age) morphometric measurements (body weight, body length, breast circumference and keel length). Pairwise correlation between the 14-week body weight (BWT) and measured variables was the highest with 2-week BWT (r=0.934, P<0.001). Application of multicollinearity diagnostics (variance inflation factor, tolerance, eigenvalues and condition index) revealed collinearity among six variables. Stepwise regression equation identified 2-week BWT as the most important predictor accounting for 87.30% of the total variation of the response variable. However, the optimum regression model for prediction of adult body weight was fitted with 2-week BWT in quadratic model having the highest predictive power (Coefficient of determination/R2/=0.966 and least root mean square error/RMSE/=4.269). This result is applicable under field conditions for both researchers and duck farmers for early selection of 14-week market body weight of Sudani ducks at 2 weeks of age. [ABSTRACT FROM AUTHOR]

Cage fish farming is an important economic activity in Brazil where tilapia (Oreochromis niloticus) is the main cultivated species. To investigate the cage fish farm as a vector for golden mussel invasion, we hypothesised that: (1) Limnoperna fortunei, a freshwater bivalve mollusc, finds greater food availability in the cage fish farm; (2) the cage fish farm favours mollusc colonisation and its nutritional status; and (3) its performance in the reservoir would vary over the year.We obtained data from limnological variables as well as the number of larvae and adult individuals, to evaluate condition index (CI) monthly from February 2015 to January of 2016. We established sampling stations at three points with fish farming and three points without fish farming (controls) in the Canoas II Reservoir, Paranapanema River, Brazil. We used principal component analysis (PCA) to identify spatial and temporal distribution of samples according to limnological variables. We performed a linear mixed model analysis to test the hypothesis of no difference between areas (fish farm and control) and time (months) for larval density and CI of L. fortunei.The first PCA axis (28.48% of variance) revealed a temporal gradient, showing the separation between cold and hot months. The second PCA axis (19.61% of variance) separated the samples of control and fish farms; fish farms displayed higher concentrations of total phosphorus, nitrite, and chlorophyll a. Larval densities of L. fortunei were higher in fish cage areas with time being responsible for 35% of this variation. Mussel CI was also higher in fish farms and time was responsible for 36% of the variation.We conclude that fish production in cages contributes to the establishment of golden mussels in the reservoir. Our results serve as a warning that other molluscs or invasive species may be favoured by aquaculture activities in aquatic environments. The colonisation of the mussel in the reservoir varies during the year in response to seasonality. [ABSTRACT FROM AUTHOR]

The current study was undertaken to investigate the ovarian cycle of freshwater pearl mussel, Lamellidens marginalis (Lamarck, 1819) collected monthly from a rearing pond in Bangladesh. Gonadal maturation was determined from 2 to 3 mm thick slices of dorso-ventral section cut from the middle of the mussels for histology. The overall male-female sex ratio, 1:1.08 did not deviate significantly from the 1:1 ratio as expected (2-test). Lamellidens marginalis females exhibited a prolonged spawning period from February to November when water temperature remains above 22 °C. Oogenesis occurred round the year although the majority of the females were in early and late-developing stages during January and February. Four distinct peaks in maturity indices (MIs) of L. marginalis females were noted during October, February, June and August when most of the females were ripe and ready for spawning. Condition indices (CIs) ranged from 0.42 ± 0.23 (September 2016) to 0.85 ± 0.25 (October 2015) by mean (± SD) exhibiting five peaks over 12-month study period. Further study should be designed to investigate the timing and brooding pattern of this freshwater unionid species. [ABSTRACT FROM AUTHOR]

Habitat patterns, growth and reproductive traits of the freshwater mussel Unio ravoisieri were investigated for the first time in two streams (Sejenane and Elmaleh) of the Ichkeul Lake basin (northern Tunisia) over the course of a year. A very similar profile was observed for the two studied populations. The median age class dominated in the age structure, indicating good recruitment and viability. The reproductive period lasted approximately 10 months (from September to June). Females at different gametogenesis stages were found during autumn, winter and spring. Gravid females were sampled during winter and spring, and larval release occurred from early spring to early summer. The number of embryos produced per female reached 84,000 per year. In Elmaleh stream, characterized by high salinity, reproduction of the mussel took place slightly earlier than in the other habitat (Sejenane). However, the variation in reproduction traits between the two populations was not significant (p > 0.05). Similar patterns, but with a difference in the timing of the breeding season, were recorded for Spanish populations. The results highlight a reproductive plasticity of U. ravoisieri and an ability to tolerate harsh abiotic conditions. Nevertheless, salinity and temperature seem to have a stressful effect on different reproductive stages, mainly during the brooding period; negative correlation was found between condition index and the two parameters: Pearson's r = 0.4–0.8; p < 0.05. To avoid their adverse effects, U. ravoisieri appears to be able to adjust its reproductive cycle to the wet season when these parameters are moderate. [ABSTRACT FROM AUTHOR]

Choosing an alternative species of mussel for the aquaculture industries, will be possible if it has equal or greater yield than the mussel cultivated. This study compares the growth of the chilean native mussel Mytilus chilensis with the non-native Mediterranean mussel Mytilus galloprovincialis and evaluate if environmental variables and cultivation depth affects mussels growth. Mussel were seeded in summer, with the same mean total weight and shell length for both species. At the end of the experiment, shell length (SL), condition index and gonadosomatic index were compared over month, depth and species. Highly significant differences were found in shell length between month and depth and between month and species (p < 0.05). The linear relationship between the gonad weight and wet meat weight in M. chilensis present a higher gonad weight for the same wet meat weight than M. galloprovincialis. It can be concluded that at the end of the harvest size cultivation M. chilensis presents a greater gonad weight, condition index and gonadosomatic index. • Growth were compared at aquaculture system between Mytilus chilensis and Mytilus galloprovincialis • No differences were found for shell length between species • Gonad weight, condition index and wet meat weight was found higher in the native mussel than non-native. [ABSTRACT FROM AUTHOR]

Abstract Estuarine abiotic characteristics vary with tidal variations and fresh water input, both driven by climatic conditions and often cyclical climatic events. Estuaries are very productive and bivalves often represent a substantial proportion of the biomass with important ecological role. Salinity fluctuation is often a key environmental factor affecting bivalves shell growth and individual condition index (CI), parameters that in turn can be used to show the quality of the environment for one population. The stout razor clam Tagelus plebeius is an euryhaline filter-feeder species that inhabits sandy-silt tidal flats within a wide salinity range. The objective of this study was to evaluate, by survey sampling and in situ transplant experiments among sites with different salinity, whether shell growth and CI of T. plebeius vary with the salinity regime. We hypothesized a higher growth and CI related to the intermediate salinity. Clams and abiotic parameters were sampled in three estuaries of the northern Argentinian coast with different salinity regimes (Bahía Samborombón (36°19′S), Mar Chiquita coastal lagoon (37°32′S) and Bahía Blanca (38° 47′S)) and in three sites along the salinity gradient of the Mar Chiquita coastal lagoon where the manipulative experiments were also conducted. Shells were more elongated in sites with lower salinity; but the growth rate (k) and the CI were higher in sites with intermediate salinity. Furthermore, clams transplanted from intermediate salinity sites to those with higher or lower salinity showed a disadvantage in shell growth. Considering the scenario of climatic-driven salinity changes in these estuaries and given that T. plebeius is the only native bivalve species in those intertidal zones, having a relevant ecological role and conspicuous fossil presence in Holocene outcrops, our results highlight the relevance of this clam as a valuable target for future studies on conservation biology and paleobiology. Highlights • The effects of salinity on Tagelus plebeius growth and condition index are evaluated. • Growth changes associated with salinity variations could be seen in field experiments. • Clams' growth is higher in sites characterized by intermediate salinity. • The study highlights the relevance of T. plebeius as a tool for conservation biology. [ABSTRACT FROM AUTHOR]

This work aims to examine the reproductive cycle of the bivalve Mactra corallina inhabiting the Gulf of Tunis (Tunisia). Histological analysis indicated that the reproductive cycle is composed of six stages and was synchronous between sexes. Gonadal development began in January. From April to July, an increase in temperature (from 16 to 28°C) and a rise in chlorophyll a (from 3.25 to 6.35 mg/L) marked the period of sexual maturity in both sexes, which was also confirmed by an elevation in condition index (CI). Partial spawning started in April for males and in May for females, peaking in late summer indicating a prolonged reproductive period. The reproductive cycle of M. corallina finished with an inactive stage during autumn. From the total number of animals used in this study, we identified 104 females (52%) and 96 males (48%) corresponding to a sex ratio 1:0.92 that did not differ significantly from a 1:1 ratio. [ABSTRACT FROM AUTHOR]

Production protocols as well as the origin of broodstock in hatcheries are the important factors determining the attributes of Crassostrea gigas oyster spat. Spat from diverse hatcheries may have different attributes for commercial activities. We described the biological performance (growth and condition index – CI) of spat stocks produced at different hatcheries (H1, H2, H3 and H4), and simultaneously cultivated in La Cruz lagoon (Mexico). Analysis of pathogens and genetic variability was performed for each stock. Temperature, salinity, chlorophyll a and seston were measured during samplings. Stocks showed similar growth patterns but each one showed a distinctive curve. Temperature was the governing factor on growth but its effect was variable depending on the stock and whether the temperature increases, stays high or decreases. Availability of food was high producing elevated CI. No presence of pathogens was detected and it was not possible to obtain amplicons of the mitochondrial regions. Despite differences in performance among stocks, all of them showed higher values (growth rates, CI, survival) than the standards reported for the Gulf of California. These findings are useful for the production and cultivation of C. gigas, but more studies are needed to understand the influence of hatchery protocols on spat quality. [ABSTRACT FROM AUTHOR]

Clarias gariepinus and Oreochromis niloticus are two hot-water fish species of African origin that have been recently reported to occur unnaturally in hot-water resources and springs in the Sakarya River Basin (northwestern Turkey). Within effective planning strategies to maintain native biodiversity, monitoring fishes' well-being can be useful to evaluate the status of nonnative fish populations and their degree of adaptation to new environments. Relative weight (Wr) is a condition index widely used to estimate the well-being of fish by comparing the actual weight of a specimen with a standard weight (Ws) that is the ideal weight of that fish at that length. In this study, length and weight data of C. gariepinus and O. niloticus, collected throughout the Sakarya River Basin, were used to estimate Ws equations. The resulting Ws equations were log10Ws = -3.668 + 1.885 log10TL + 0.2087 (log10TL)2 (TL range: 18-45 cm) for C. gariepinus and log10Ws = -8.796 + 6.751 log10TL - 0.8479 (log10TL)2 (TL range: 8-28 cm) for O. niloticus. The use of these Ws equations to estimate the fishes' condition is suggested as a monitoring tool to assess the status and the best management actions of these two nonnative species populations throughout the Sakarya River Basin. [ABSTRACT FROM AUTHOR]

The Arctic marine environment is rapidly changing with rising sea surface temperatures, declining sea ice habitat and projected increases in boreal species invasions. The success of resident Arctic fish will depend on both their thermal tolerance and their ability to cope with changing trophic interactions. Larval fish energetic condition is closely associated with mortality rates and therefore provides an indicator of overall well-being or fitness. In this study, we experimentally determined larval morphometric and lipid-based condition in an Arctic gadid (Arctic cod, Boreogadus saida) and a boreal gadid (walleye pollock, Gadus chalcogrammus) in response to different temperatures and food rations. Our results suggest that larval condition is highly sensitive to both factors but varies in a species- and ontogenetic-dependent manner. Results indicated that condition metrics based on length–weight relationships were not as sensitive as those based on lipid storage. Further, condition metrics changed with ontogeny and were best used within a developmental stage rather than across developmental stages. As expected, larval condition in first-feeding Arctic cod was higher at colder temperatures (2–5°C) than in the boreal gadid (5–12°C). However, at more developed larval stages the peak condition for Arctic cod was at warmer temperatures (7°C), while walleye pollock had the same thermal optimum as during earlier stages. Arctic cod were more sensitive to food ration at first feeding than walleye pollock, however; at later larval stages both species had a negative condition response to low food ration, especially at elevated temperatures (5 vs. 7°C). The lower thermal tolerance of Arctic cod, coupled with a higher sensitivity to food availability indicates that Arctic cod are particularly vulnerable to on-going environmental change. Arctic cod is a lipid-rich keystone species and therefore a reduction in their energetic condition during summer has the potential to affect the health of higher trophic levels throughout the Alaskan Arctic. [ABSTRACT FROM AUTHOR]

In Portugal, the European clam (Ruditapes decussatus) is an important commercial resource. Óbidos Lagoon is a strong candidate as a cultivation area to increase European clam exploitation. However, the reproductive biology of this population has not been described. In this work, the reproductive cycle of R. decussatus was characterized by determining gonadal development stages, gonad index, condition index, and biochemical composition. The relationship between reproduction and environmental parameters (sea surface temperature, chlorophyll a, and particulate organic matter) was assessed. Ruditapes decussatus had an annual reproductive cycle. The gametogenic cycle started in late winter, and the ripe stage in spring was followed by spawning that began at the end of spring/early summer and extended until early autumn. The subsequent period of sexual rest occurred during the winter. Condition index showed seasonal variations related to food availability (chlorophyll a). The European clams in Óbidos Lagoon recovered rapidly after their reproductive period, most likely owing to the availability of food. This study will help to improve sustainable management of this wild stock and is important for future aquaculture development of this species. [ABSTRACT FROM AUTHOR]

This study reports, for the first time, data on nutritional quality parameters in Tunisian mussels, Mytilus galloprovincialis , with an especial emphasis on lipid compounds. Mussel condition index (CI), proximate composition and fatty acid profiles were investigated for a one year period in order to identify the best harvesting period. Analysis revealed that polyunsaturated fatty acids (PUFA) were the dominant fatty acids with a prevalence of n-3 over n-6 forms. Pearson’s correlation indicated a strong relationship between CI and PUFA compound and Principal Components Analysis suggested that, from winter to summer, the product maintained a condition sufficiently good for marketing. The best CI and lipid quantity/quality occurred during summer and this may be used as criteria for product labelling. The study also included a thorough literature review that allowed data comparison on mussels from various Mediterranean sites and allowed the mussels from the Bizerte lagoon (North of Tunisia) to be differentiated. [ABSTRACT FROM AUTHOR]