Survival Of Mussels Research Articles

Increasing mussel transplantation success by initiating self-facilitating feedback mechanisms

Transplantation success of ecosystem-engineering species can be low in dynamic environments, as such ecosystem-engineers often require density-dependent positive feedback mechanisms to overcome environmental stressors. These self-facilitating feedback mechanisms play an important role in self-organization, whereby complex systems tend to organize and create patterns in order to ameliorating physical and/or biological stressors. In this study we used biodegradable structures to ameliorate self-facilitating feedback mechanisms to overcome environmental stressors in the initial post-transplantation phase. The biodegradable structures tested are an innovation of the traditional Seed Mussel Collectors (SMCs) used in mussel cultivation. The so-called “BioShell-SMC” does not contain any plastic, but is made up of a coconut fiber rope surrounded by empty cockle shells and held together by a biodegradable net based on a compound of aliphatic polyesters. We tested if the survival of two size classes of blue mussel (Mytilus edulis) transplants, on a tidal flat in the Oosterschelde estuary in the Netherlands, increased when mussel seed was transplanted attached to the BioShell-SMCs instead of single mussels in combination with empty cockle shells. The results of this study revealed that the survival of larger mussel seed significantly improved when attached to the BioShell-SMC compared to those transplanted loosely. Factors contributing to the difference in mussel loss between BioShell-SMC mussels and loosely transplanted mussels include predation, competition and dislodgement due to hydrodynamic forces. For small mussel seed, mussel biomass decreased strongly in the first three days of the experiment, irrespective of transplantation method. This is due the small size of the mussels in combination with low mussel densities. Overall, this study highlights the potential of using biodegradable structures to initiate self-facilitating feedback mechanisms in establishment of ecosystem engineers in dynamic environments.

EFEKTIVITAS SUHU TERHADAP KELANGSUNGAN HIDUP KERANG ABALONE Haliotis squamata

Abalone (Haliotis squamata) is a species of mollusk that has important economic value. The high market demand causes an increase in the level of exploitation in nature. Therefore, abalone cultivation activities in controlled containers must be carried out to meet market demand and prevent over-exploitation in nature. One of the parameters that must be considered for the success of abalone cultivation is temperature. This study aims to determine the effect of different temperatures on the survival rate of abalone shellfish. This study used a completely randomized design with 3 treatments, A (temperature 24 oC), B (temperature 27 oC), C (temperature 30 oC) and temperature 29 oC as a control. The parameters measured were the survival and weight growth of abalone mussels. The results showed that the highest survival rate was in treatment A with a value of 70% and B with a value of 50%. The lowest survival rate was in treatment C with a value of 40% while the weight growth of abalone mussels in treatment A increased more with the growth value of abalone weight 8.91 gr. Based on the results of the analysis of variance ANOVA showed that the temperature difference treatment had a significant effect on the survival of abalone shells where F count 2.126 F table 0.219 and the results of calculating the weight of abalone shells that were kept at different temperature media obtained F count 3.385 F table 0.140, which means there was a significant difference in the survival and growth of abalone shell weights.

Warming and parasitism impair the performance of Baltic native and invasive macroalgae and their associated fauna

AbstractGlobal warming, bioinvasions, and parasitism affect single‐species performances and species interactions, substantially impacting the structure and stability of marine ecosystems. In light of accelerated global change, the information derived from studies focusing on single species and single drivers is insufficient, calling for a multi‐stressor approach under near‐natural conditions. We investigated the effects of warming (+3°C) on the performance of a benthic community composed of native and invasive macroalgae, consumers and a trematode parasite in a mesocosm setting. We also assessed the effects of warming and parasitism on the survival and growth of gastropods and mussels and the thermal dependency of trematode performance. Our findings show that warming and grazing by infected gastropods had a large detrimental effect on the invasive macroalga growth. Furthermore, the single and interactive effects of parasitism and warming were detrimental to intermediate host survival and growth, especially to large mussels. Finally, cercarial emergence positively correlated to the natural peaks of summer temperatures, while infection intensity in mussels was higher in larger individuals. Our findings suggest that grazing and warming will be detrimental to the invasive macroalga, favoring the native alga. Moreover, parasitism will enhance grazing, especially in summer, when higher temperatures trigger parasite development. However, parasite‐enhanced grazing may be buffered by higher mortality or a shift in the size of infected intermediate hosts under warming. Our findings demonstrate how complex effects of ocean warming can be on food webs and how they can be mediated by parasitism and, as a result, influence native and invasive macroalgae differently.

Determining restoration potential by transplanting mussels of different size classes over a range of aerial exposures

Restoration of mussels typically focuses on either subtidal or intertidal habitats, although it is important to consider the full historical range of a species. However, it remains unclear how environmental changes can impact the ability of mussels to survive in tidal heights where they occurred historically. Additionally, there is limited research on the viability of reducing mussel stock size for restoration purposes. In this study, green-lipped mussels Perna canaliculus of 2 size classes (80 and 60 mm) were assessed when transplanted as a single size class or as mixed cohorts in 9 m2 plots at 3 shore heights (i.e. neap low tide, spring low tide, and subtidal). The mussels were sampled over a 1 yr period to understand the effect that shore height and size class had on mussel metrics, such as survival, growth, and condition. The results revealed that shore height had a greater effect than size class on mussel survival, with a total loss of mussels transplanted into areas that were exposed at neap tides in contrast to 39% mussel survival transplanted into areas that were only exposed on spring low tides. Further, mussels transplanted in the adjacent subtidal had higher overall survival (74%). This suggests that aerial exposure time determines the upper vertical limit for restoration by transplantation of mussels sourced from aquaculture, despite their historical distribution. The results of this study also support the use of smaller mussels (~60 mm) for transplantation for mussel reef restoration, as a 25% reduction in size resulted in 50% more mussels being deployed.

Complex interplays between limpets and alien species in South Africa: multispecies interactions, zonation and size effects

Integrating observations and experiments, we address the progressive effects of three alien species, the musselsMytilus galloprovincialisandSemimytilus patagonicus, and the barnacleBalanus glandula, on limpet species in South Africa. We describe four aspects: (1) Interactions among algae, the limpetScutellastra granularisandM. galloprovincialis. (2) The influences ofB. glandulaonS.granularisand on the periwinkleAfrolittorina knysnaensis. (3) Transformation of the zonation ofS. granularisby the successive arrival of these three aliens. (4) Assessment of how effective the published predictors of the effects ofM. galloprovincialishave been when applied toS. patagonicus. We conclude: (a)Scutellastra granularisimproves mussel survival and condition by regulating algae that would otherwise overgrow and smother the mussels. (b)Balanus glandulahas largely occupied the upper half of rocky shores, and at high densities depletes or eliminates suitable bare-rock habitat forS. granularis. However, it has positive effects on another gastropod,A. knysnaensis.(c)Mytilus galloprovincialisdominates the midshore and has positive effects on the recruitment ofS. granularis, but negatively influences adults of this limpet, so that its size composition, density, reproductive output and zonation are all altered by this mussel. (d)Semimytilus patagonicuspresents different challenges to those created byM. galloprovincialis, settling at much greater densities, lower down the shore, and reaching smaller maximum sizes. Rather than generating a favourable habitat for epizooticS. granularisrecruits and juveniles, it almost completely excludes that limpet. We conclude that the influences of alien species are not readily predictable, depending on the nature of the invader and recipient species, environmental conditions and complex interactions among species. Collectively, the three alien species now cover almost all zones on wave-exposed rocky shores, completing the ‘zonation squeeze’ on limpets, but are less influential on wave-sheltered shores and in years when recruitment is low.

POTENSI KIJING LOKAL (Pilsbryoconcha exilis) SEBAGAI BIOFILTER TERHADAP PENURUNAN KADAR SIANIDA (CN)

Local gravestone (Pilsbryconcha exilis) is an animal that lives in fresh waters such as rivers, lakes, and other waters. The survival of local mussels is very high so that in large quantities it can be used as a water purification process due to pollutants and heavy metal pollution. Cyanide is commonly used to extract gold ore, waste that is wasted in waterways contains a lot of CN compounds so that it can pollute the living things in it. The purpose of this study was to determine the potential of local gravestone (Pilsbryoconcha exilis) as a biofilter to decrease cyanide (CN) levels. This study consisted of three treatments and one control (without KCN) with one replication. The number of mussels in each treatment amounted to 10 tails with the concentration of cyanide used was 0.04; 0.07; and 0.1 ppm. The results of this study indicate that local gravestone can affect the decrease in cyanide levels in the experimental aquarium media. In the treatment with KCN concentration of 0.07 ppm there was a decrease in cyanide levels of 0.011 mg/L and the treatment with 0.1 ppm KCN concentration decreased cyanide levels of 0.025 mg/L. The survival rate of the mussel during the research process was 100%, because there were no local dead mussels found. The best daily growth rate was in treatment 3 with 0.1 ppm KCN concentration of 2.3%.

Salinity and pH effects on survival, growth, and reproduction of quagga mussels.

In recent decades, invasive quagga mussels have expanded to the Western United States from the Great Lakes region of North America. Most studies that evaluate the invasion potential of quagga mussels in western water bodies have utilized physiological and life history information from zebra mussels, a related taxon. Few studies have assessed the potential for invasion using specific information from quagga mussel life history or experiments that test for their survival in the fresh and saline waters of the western United States. We investigated quagga mussel survival, growth, and reproduction using semi-natural experiments under temperature and light controlled conditions across a gradient of water salinity (fresh to brackish) and pH (8.4-11). Water from Lake Mead was used as a positive control in our experiment, and water from Pyramid Lake and the Truckee River was used as brackish and freshwater treatments, respectively. The mussels used in the experiments were collected from Lake Mead. After 12 h in brackish water (4 ppt, pH 9.3), we observed 100% mortality of adult mussels. The swelling and disintegration of body tissues and high mortality rates indicated that high potassium, sodium, and chloride concentrations were the likely causes of death in brackish water treatments. In contrast, mussels were able to survive, grow, and reach sexual maturity in freshwater (0.1 ppt) with a low calcium concentration (17 mg L-1) after 57 days. Mussels died after 2 days at pH 11 and after 12 days at pH 10; during the 14-day monitoring period, no mortality was detected at pH 9.0, 9.3, or 9.5 and mussels did not exhibit any visual indications of stress. Understanding quagga mussel physiological and environmental tolerances appears to be essential for assessing their invasion potential in aquatic habitats.

Dreissena polymorpha responses under thermal and hypoxic stress: New insights in the tolerance of this freshwater sentinel species

Dreissena polymorpha is a sentinel freshwater mussel providing key functional ecosystemic services like nutrient recycling and suspended matter filtration. Global warming and especially extreme events imply rapid fluctuations of environmental parameters that sessile organisms could not escape. The increase occurrence of heat waves and the subsequent expansion of hypoxic areas could challenge the survival of mussels. This study provided a deeper knowledge of energy management and cellular function during thermal (+15 °C) or hypoxic (30% of dissolved oxygen saturation) stress for 7 days. A potential metabolic rate depression was highlighted in D. polymorpha under hypoxia through a decline in the mitochondrial activity and a constant AMP content over time. A contrasted pattern of response was observed in thermal-stressed mussels between 24 h and 7 days of exposure. A global increase of metabolic activity was noticed in mussels after 24 h while a return to control level was noticed at the end of the experiment. Although D. polymorpha is considered as a temperature tolerant species, a significant increase of ADP:ATP ratio, related to a decrease of mitochondrial activity and density, suggested an overwhelming of organisms. This study pointed to the importance of considering time of exposure to natural factor variations in tolerance window of organisms in a long-term changing environment. The apparent short-term tolerance of D. polymorpha could hide much more deleterious consequences, i.e. mortality, if abiotic stresses persist, as suggested by climate change models.

Survival and growth assessment after reintroduction of the pocketbook mussel, Lampsilis cardium Rafinesque, 1820 among three streams in Nebraska (USA)

Abstract Freshwater mussels are a globally diverse and fundamental group in aquatic ecosystems. However, 65% of freshwater mussel species have become endangered over the past century and 10% of them are already extinct. Natural population preservation and restoration efforts have been expedited, but the complicated life history of this taxon presents many challenges since species‐specific ecology involved in restoration projects is often poorly understood. Lampsilis cardium is an imperilled freshwater mussel in Nebraska, USA. A reintroduction project has been carried out to restore L. cardium populations among three streams in Nebraska, during autumn 2016 and summer 2017. A 2‐year mark–recapture study was used to determine habitat, timing and size‐at‐introduction effects on mussel survival and growth following introduction. Water quality and habitat parameters were seasonally recorded from each site to assess potential effects on mussel growth and survival. The highest daily growth rates of L. cardium ranged between 145 and 185 μm d−1, whereas the lowest daily growth rates observed were ∼88–107 μm d−1, with the greater rate of shell growth always recorded for those individuals introduced in spring and lower for those individuals introduced in summer or autumn. Survival models indicated that mussels were most susceptible to mortality immediately following introduction in spring, whereas size at introduction had almost no effect on survival. At each site, habitat parameter measurements recorded during different seasons indicated that calcium availability, water temperatures, water depth and water quality may contribute to differences in growth and survival rates. Survival rate estimation and population growth predictions are essential knowledge to understand population dynamics; this study provides useful information and a framework for management decisions that may influence L. cardium population dynamics, such as identifying more suitable habitats and introduction times not only for this species but also other similar unionids.

Growth performance and survival of oyster, Saccostrea cucullata (Born, 1778) and green mussel, Perna viridis (Linnaeus, 1758) cultivated in Bangladesh Coast

Oyster and mussel farming along the coasts and the desire to increase fishing revenue have created a boom in these types of farms. An experiment on culture of edible oyster (Saccostrea cucullata) and green mussel (Perna viridis) was performed at Gangamoti estuary in Kuakata, Bay of Bengal coast of Bangladesh from December 2021 to March 2022 to find out the appropriate culture method of the oyster, S. cucullata and green mussel, P. viridis. Initially, the average shell heights of S. cucullata and P. viridis were 8.8±1.62 and 6.9±1.89 cm, respectively; where average weights were153.4±13.23 and 84.78±11.78 g, respectively. After the culture period, oysters shell height and weight grew up to 9.1±1.98 cm and 163.2±12.54 g, respectively in rectangular basket and 8.9±1.45 cm and 157.2±11.31 g, respectively in velon screen bag. In case of oysters, the rectangular basket and velon screen bag displayed the minor progress in specific growth rate, 0.09±0.01 and 0.07±0.03, respectively. But green mussels did not show any growth rate. Oysters cultured in rectangular basket showed total mortality at day-90 and velon screen bag at day-75. Green mussels showed 100% mortality within 21 days of culture. Our experiment was the first attempt to culture these two mollusks in the Kuakata coast of Bangladesh. However, further intensive researches would be required to evaluate the culture feasibility of these two mollusks’ species in the Kuakata coast of Bangladesh.

Potential for Concentrated Microalgae as Replacement Diets for Juvenile Green-Lipped Mussels, Perna canaliculus

The nursery culture of bivalves typically relies on the feeding of costly live microalgae, while the use of natural sources of phytoplankton for feed is uncertain due to their variable quality and abundance. Replacement diets have been applied in bivalve nursery culture to replace live microalgae with varying success. This study investigated the potential use of two concentrated microalgal diets at a range of levels of substitution with live microalgae. Shellfish Diet 1800® (called SD) and LPB™ Frozen Shellfish Diet® (called LPB) were fed to juvenile green-lipped mussels (Perna canaliculus) at five levels of substitution for live microalgae (i.e., 0, 25, 50, 75, and 100%) for 27 days. The mortality of mussels fed with 100% LPB replacement was significantly higher than the mortality of mussels fed at the lower levels of replacement, i.e., 0 and 25%. The overall final size of spat tended to decrease with the increasing level replacement of live microalgae. Proximate analysis (i.e., crude ash-free dry weight, crude protein, crude lipid, and carbohydrate) showed that only the proportion of carbohydrate content of spat was influenced by feeding treatments, with the mean total carbohydrate content of mussels tending to decrease with increasing levels of replacement of live microalgae. The results indicate that both concentrated microalgal feeds (SD and LPB) are effective at replacing live microalgae by up to 50% without compromising the survival and nutritional profile (AFDW, protein, lipid, and carbohydrate content) of juvenile green-lipped mussels and are therefore a useful resource for improving the efficiency of production.

The effect of high oxygen modified atmospheres on the quality degradation of packed live blue mussels (Mytilus edulis)

Oxygen (O2) plays a vital role in the blue mussel (Mytilus edulis) survival, microbial growth, and volatile organic compounds (VOCs) formation during transport and storage. This study measures the impact of different atmospheres (% CO2/O2/N2): 30/40/30; 40/60/0; and 0/60/40 on blue mussels' spoilage. Quality parameters were monitored at 4 °C for up to 16 days of storage, including headspace composition (% CO2/O2), pH, mortality, microbial analysis, and VOCs concentrations. Selected-ion flow-tube mass spectrometry (SIFT-MS) was used for real-time VOCs measurements. At the end of storage, odor activity values (OAVs) were calculated to assess VOCs that contributed to the overall odor profiles (OAV ≥1). Different atmospheres result in a different shelf life in which B60 condition (% CO2/O2/N2: 40/60/0) prolonged the life span of blue mussels for nine days of storage. A total of 23 compounds were identified in packed blue mussels. The evolution of ethanol; 3-methyl-1-butanol; 2,3-butanediol; acetone; 2,3-butanedione; dimethylamine (DMA); dimethyl sulfide; dimethyl disulfide; and methyl mercaptan were associated with mortality and total plate count (TPC >7 log CFU g−1). This study identifies dimethyl sulfide and methyl mercaptan as the primary contributors to malodor of blue mussels at the end of storage (OAVs = 182–66716).

Testing habitat suitability for shellfish restoration with small‐scale pilot experiments

AbstractThe global loss in ecosystem engineers has initiated calls for restoration, which includes the UN declaration of 2021–2030 as the decade of ecosystem restoration. As researchers dive into this decade it is important to consider the current state of an ecosystem to ensure restoration success. Pilot‐scale restoration has been recommended by global guidelines and standards as an effective starting point for restoration to provide valuable initial information to increase efficiency and success of subsequent larger‐scale restoration. To test habitat suitability, 4 t of green‐lipped mussels were placed onto three 2.25 m2plots at five locations with differing benthic environments and assessed over 2 years. This study had a mean of 85% mussel survival at four of the five locations, while the restored shellfish in one location were completely extirpated, most likely by sea star predation. This pilot‐scale restoration revealed location‐specific differences that have implications for ensuring larger‐scale restoration success, including mussel survival, density, and health, and recommends a timeframe of at least 18 months to properly assess habitat suitability. Overall, the results validated the efficacy of using small‐scale pilot experiments to test habitat suitability and optimize location selection to maximize success and efficiency of larger‐scale restoration efforts.

The Effectiveness of Providing Shell Substrate for the Restoration of Adult Mussel Reefs

Providing benthic substrate is the most common method used for oyster reef restoration. The physical relief from the seabed, increased habitat complexity, and attachment surfaces have been shown to improve oyster health, recruitment, and survival. While the addition of shell material is an effective substrate for oyster restoration, its usefulness in mussel restoration has been understudied. This study tested the effectiveness of adding shell substrate to two different types of soft sediment for the restoration of adult green-lipped mussels. Over 10 t of shell was used to create a 10 cm layer on the seabed in replicated experimental plots at the two locations. 10 t of live adult mussels were deployed onto the shell substrate and an additional 10 t of mussels onto adjacent soft sediment control plots. A year after deploying the live mussels, mussel survival across all plots was 80.6 ± 6.5%, with no differences between mussel plots with or without the added shell substrate for either of the two locations. This study emphasizes the importance of context-dependency, revealing promising avenues for future research, and indicates that for adult green-lipped mussels the addition of a shell substrate appears to provide little advantage for adult mussel restoration at high deployment densities.

Combined Effects of Temperature and Salinity Affect the Surviv-Al of Asian Green Mussel (Perna viridis) through Digestive and Antioxidant Performance.

Changes in temperature and salinity of the marine environment fluctuate continuously, and the effects of these changes on shellfish survival are significant. In this study, the survival rate of adult Asian green mussels (Perna viridis) was measured after short-term treatments (7 days) for a range of temperature (20 °C, 25 °C, 30 °C) and salinity (23‰, 28‰, 33‰). The digestive (amylase, lipase, trypsin and pepsin activities) and antioxidant performance (SOD and GPX gene expression; SOD, GPX and CAT activities; GSH and MDA Concentration) were measured and MANOVA results were obtained using a generalized linear model between certain factors (temperature (T), salinity (S) and temperature × salinity (T × S)) and survival rate. Both T and T × S significantly affected the survival rate of Asian green mussels. The overall relationship between the survival rate of P. viridis and T and S within the experimental range can be summarised by the equation: ln(Survival rate) = 54.9282 − 2.5627 × T − 3.6180 × S + 0.1857 × T × S + 0.0156 × T2 + 0.0520 × S2 − 0.0012 × T2 × S − 0.0023 × T × S2. The optimal temperature–salinity combination was 23.698 °C/30.760‰. T, S and T × S all had a significant impact on amylase and lipase activities of Asian green mussels. In the hepatopancreas, gill, mantle, adductor muscle, gonad and foot tissues of Asian green mussel, the SOD and GPX gene expression were responsive to temperature–salinity changes. The antioxidant performance of the combinations far from the optimal temperature–salinity combination were significantly improved. Our results suggest that combined temperature and salinity effects have a regular impact on the survival of Asian green mussels and that there is a link between survival and digestive and antioxidant performance.

Natural heavy metal concentrations in seawater as a possible cause of low survival of larval mussels

BackgroundA period of seismic activity starting in 2010 coincided with a decline in commercial catches of wild seed mussels in a major aquaculture production region of New Zealand. Analyses of over 40 years of mussel seed catch data from in the Pelorus and Kenepuru Sounds, confirmed a marked decline since 2010 in catches of the preferred, green-lipped mussel (Perna canaliculus), the larvae of which is known to have low tolerance of heavy metals in seawater. MethodsHeavy metal mean concentrations were measured throughout the Pelorus and Kenepuru Sounds. The concentrations ranged from < 0.60–3.24, < 16.94–74.35, < 1.47–4.00, 2.23–19.02, 1.86–3.29 and 0.12–0.52 µg L−1 for Cr, Fe, Cu, Zn, As, and Cd, respectively. Seawater from six locations in the Sounds, historically associated with high commercial catches of settling mussel larvae, was used for experimental rearing of green-lipped mussel larvae. ResultsNo mussel embryos survived when incubated in these seawater samples. The mean concentrations of Cr, Fe, As, and Cd were significantly higher in the seawater from the Sounds than in the hatchery seawater. A higher concentration of one or a combination of these heavy metals could be the cause of the poor larval survival. These findings could be crucial for the sustainability of mussel farming in the area.

Hydrology and invasive macrophytes may mediate freshwater mussel density and population size structure in a hydropeaking reservoir

Globally-threatened freshwater mussels belonging to the order Unionida (Bivalvia) may be adversely affected by dense beds of submerged macrophytes that modify habitat at the sediment-water interface. Such effects can be particularly pronounced in modified lentic ecosystems such as reservoirs which are subject to hydrological regimes (e.g., hydropeaking) that can exacerbate macrophyte-mediated impacts, including anoxic or hypoxic conditions, the related release of toxic ions (e.g., ammonia), and silt accumulation that inhibits filter-feeding. Accordingly, we compared how population size-structure and biomass of the New Zealand mussel Echyridella menziesii varied inside and outside of dense beds of invasive macrophytes known to have similar impacts on water chemistry (e.g., anoxia) in two northern New Zealand hydroreservoir locations with contrasting hydrology (lacustrine location dominated by Ceratophyllum demersum; and riverine location dominated by Egeria densa). We found adverse sediment-water interface conditions were not always associated with dense submerged macrophyte beds in littoral zones. Nonetheless, where they occurred, adverse sediment-water interface conditions were related to reduced mussel density and adult skewed size-structure, inferring reduced recruitment. Disentangling direct and indirect effects with structural equation modelling indicated that increased pore-water ammonia did not impact these primarily adult populations of freshwater mussels. Increased sediment organic matter, silt, and previously recorded hypoxia and anoxia were exacerbated in the lacustrine section where variable flows promoting water mixing were not present. High densities of mussels <40 mm in length were associated with favourable sediment-water interface conditions of low silt and sediment organic matter, suggesting that enhanced water exchange in and around macrophyte beds may increase juvenile mussel survival in littoral zones of the riverine lake section. Our findings highlight a potential role for hydropeaking management in mitigating the development of adverse physicochemical conditions, and underscore the context-specific effects that dense non-native macrophyte beds can have on mussel populations.

Ecotoxicological effects of the UV-filter 4-MBC on sperms and adults of the mussel Mytilus galloprovincialis

Present in an increasing number of products, UV-filters are continuously discharged into aquatic environments. Despite potential risks for inhabiting organisms are recognized, the effects of UV-filter 4-methylbenzylidenecamphor (4-MBC) on marine invertebrates are poorly investigated. By combining in vitro/in vivo exposures through a multi-biomarker approach on sperms and adults, the present study evaluated how 4-MBC affect the mussel species Mytilus galloprovincialis, providing ecologically relevant information on organisms' responses. From the obtained results, considering mortality as endpoint, sperms revealed a greater sensitivity (EC50:347 μg/L) than adults (EC50: not calculable). From an ecotoxicological perspective, this resulted in a derived threshold concentration (LOEC) of 100 μg/L and 72 μg/L, respectively. Effects at the cell/molecular level were provided by general redox-status imbalance and oxidative stress. Sperms showed functional and structural impairments, hyperactivation and DNA damage, while adults showed physiological, metabolic/energetic dysfunctions, DNA damage and activation of oxidative and biotransformation enzymes. High 4-MBC bioaccumulation was also observed in exposed mussels (BCFs:14.0-32.0 L/kg). These findings suggest that 4-MBC may impair fitness and survival of the broadcast spawning mussel M. galloprovincialis, affecting reproduction success and population growth.

The last hope: the struggle for survival of fan mussels in the Gulf of Erdek, Sea of Marmara, Turkey

This study presents the results of the first broad-scale assessment of the spatial distribution of the fan mussel (Pinna nobilis Linnaeus, 1758) population in the Gulf of Erdek (Sea of Marmara, Turkey), based on underwater surveys. The population density and structure of mussels were estimated by diving along strip transects between the shoreline and a depth of 15.8 m, in a study area of 9080 km2. A total of 2164 mussels were counted, of which 78.8% were alive, and 21.2% were dead in 29 sites. The mean density was calculated as 18.3 ± 3.3 ind·100 m-2, and recorded densities reached 71.2 ind·100 m-2 among the studied sites. Although mussel density was very high (&gt;15 ind·100 m-2) in nine sites, dead mussels were also recorded in the gulf. Benthic habitats, depth range, and exposure levels seem to play a crucial role in the spatial distribution and survival of fan mussels. The average height (± SE) was calculated as 19.5 ± 0.35 cm and 24.9 ± 0.37 cm for alive and dead mussels, respectively. The percentage of juveniles (≤20 cm) was 57% in the population, and they dominated in seagrass meadow beds and shallow waters. Despite many deaths due to uncertain causes, the results indicate a partially promising scenario for the fan mussel population in the Gulf of Erdek and highlight the existence of many alive juveniles that could play a primary role in the sustainability of the population. This situation is not static, as anthropogenic changes and human activities could affect population welfare in the future. These high-density sites need to be protected, and protection measures in these locations should include all effects that may cause incidental mortality.

Effects of food abundance on juvenile freshwater mussel survival and growth in aquaculture, and comparison with growth in streams

Captive propagation has become an important tool in the conservation of imperiled freshwater mussels. Previous studies provide conflicting results about the effects of food abundance on survival and growth of juvenile mussels in aquaculture, and the extent to which growth in the hatchery reflects growth in the wild is unknown. We evaluated the effects of abundance of an algal-based diet on survival and growth of juvenile Cumberland Bean (Venustaconcha troostensis) in a recirculating aquaculture system. We compared food abundance (as fine particulate organic matter, FPOM) in our experimental food rations with FPOM in 14 streams to assess the similarity of hatchery and natural food sources. We compared growth in our experiments with previously published growth estimates of Cumberland Bean at 17 stream sites. Growth in the hatchery increased linearly with increasing food abundance from 3.5 to 27.6 mg/L algal dry mass (about 111,000–1,147,225 cells/mL), and mussel size after two weeks increased 2.9% for every doubling of algal dry mass within the range of our experimental rations. We observed no negative effects of increasing food abundance on survival, and ammonia concentrations remained below chronic effect concentrations in all treatments, even in food rations much higher than recommended by previous studies. FPOM in our experiments spanned a similar range of values as FPOM in streams. Growth in our experiments was similar to growth in streams, but our experimental temperatures were higher than in streams. When the probable effect of temperature was accounted for, growth in most experimental food rations was substantially lower than expected in streams despite similar FPOM. This suggests that food quality or other conditions are more favorable for mussel growth in the wild.