Larval Ecology Research Articles

Larval trophic ecology of small pelagic fishes: a review of recent advances and pathways to fill remaining knowledge gaps

Early life stages constitute a bottleneck for most fish populations, particularly for small pelagic fish (SPF), for which the interannual variability in recruitment strength is very high, and recruits frequently constitute the bulk of the population biomass. Finding the right prey (in terms of size and quality) during these early stages is critical for recruitment success. In this work, we synthesize the available literature on the trophic ecology of the early life stages of SPF, particularly clupeiforms. Works published during the last decade (2013-2022, 37 papers) were compared to those published previously (1920-2012, 107 papers). Gut content analysis of field-caught larvae is still the most commonly used technique (44%), while the use of biomarkers (e.g. stable isotopes and fatty acid composition), molecular tools (e.g. metabarcoding) and multitrophic approaches has increased in the last decade. Significant new knowledge was gained recently, such as that on larval feeding rates and behavior through laboratory experiments for species kept in culture (e.g. Atlantic herring, Pacific and Atlantic sardines), but some old challenges remain, such as the high vacuity rates of field-caught larvae. Lastly, we provide recommendations for future studies, such as the use of complementary techniques, the importance of studying ontogenetic shifts, the use of metabarcoding for analyzing the diet of early larvae that depend on microplankton, and the identification of prey with high taxonomic resolution. Such studies are essential to better understand larval growth and survival at sea, and thus to better understand and predict SPF population dynamics.

Diversity and Distribution of Culicidian Fauna in Urban and Rural Areas of Setif Region (North-East Algeria).

Objective: The study explored larval mosquito breeding sites in urban and rural areas from March 2021 to February 2022 in the North-East region of Algeria to provide information on larval biology and ecology of different mosquito species. Methodology: It focused on the effect of the physicochemical characteristics of the breeding sites (pH and water temperature), area, and months on the larval mosquito abundance. Diversity index and equitability were calculated for the registered mosquito species in both areas. Results: Months significantly affected the larval mosquito abundances, with a clear abundance increase from March to August 2021, and then, a clear decrease to February 2022. The interactions between rural and urban areas, water pH, and water temperature as well affected the mosquito abundance. Twelve species of Culicidae were identified and distributed in three genera: Culex, Culiseta, and Aedes. Culex pipiens was the most dominant species in rural and urban sites, with a rate of 69% and 48%, respectively. In rural site, Aedes caspius and Aedes vexans occupied the second position with value of 7-8% each. In urban sites, the second position was occupied by Culiseta longiareolata (36%) and then by Culex theileri (10%). In terms of site diversity, only one site was highly diversified in rural sites, El Hchichia (H' = 1.12 bits). In urban sites, Setif Center, Guellel an Ain Trick, had almost similar diversity with values between 1.03 and 1.04 bits. Equitability values were 0.48 in rural sites and 0.55 in urban sites. Therefore, the Culicidae species presented in these study sites are moderately balanced. Conclusion: The present study provides key tools for planning a better vector control through the information on the effect of some factors on the proliferation of mosquitoes in the urban and rural sites of the Setif region and on the Culicidae diversity and abundance.

Application of biomolecular techniques on tsetse fly puparia for species identification at larvipostion sites.

Puparia are commonly found in tsetse fly larviposition sites during studies on larval ecology. This chitinous shell is representative of past or ongoing exploitation of these sites by tsetse flies. The morphological characteristics of the puparium are not sufficiently distinctive to allow identification of the species. This study explores the applicability of biomolecular techniques on empty puparia for tsetse fly species identification. Five techniques were compared for DNA extraction from tsetse fly puparia, 1/Chelex® 100 Resin, 2/CTAB, 3/Livak's protocol, 4/DEB + proteinase K and 5/QIAamp® DNA Mini kit, using two homogenisation methods (manual and automated). Using a combination of two primer pairs, Chelex, CTAB, and DEB + K proved the most efficient on fresh puparia with 90, 85, and 70% samples identified, respectively. Shifting from fresh to one- to nine-month-old puparia, the Chelex method gave the best result allowing species identification on puparia up to seven months old. The subsequent testing of the Chelex extraction protocol identified 152 (60%) of 252 field-collected puparia samples at species level. The results show that reliable genetic identification of tsetse flies species can be performed from empty puparia, what can prove of great interest for future ecological studies on larviposition sites. The Chelex technique was the most efficient for DNA extraction, though the age-limit of the samples stood at seven months, beyond which DNA degradation probably compromises the genetic analysis.

Seasonal Diversity in Mosquito Larval Ecology and Its Public Health Implications in Urban Slums of Lagos, Nigeria.

Mosquito-borne diseases (MBDs) are major public health burdens in tropical nations, including Nigeria. This study assessed mosquito larval species composition, abundance, and abiotic factors influencing mosquito breeding in slum communities of Lagos with the goal of informing MBD control measures. Three slum communities-Bariga, Makoko, and Ajegunle-were selected along with the nonslum community of Ikeja, which served as a control site. Larval sampling was done using the standard dipping technique between December 2021 and July 2022 across the dry and wet seasons. Mosquito larvae were raised to adults and identified using morphological keys and molecular assays. A total of 57,753 immature mosquitoes were collected from all study sites, with a significantly (P < 0.05) greater abundance in the dry season than the wet season. The majority (98.1%) of the mosquitoes collected belonged to Culex pipiens s.l., the only species found during the dry season in almost all locations. In the wet season, species identified from all sites combined were Anopheles gambiae ss., Anopheles arabiensis, Aedes aegypti, Aedes albopictus, Cx. pipiens s.l., and Lutzia tigripes, with Ajegunle having the greatest species diversity (H = 0.593). Among physicochemical parameters measured, only water temperature had a significant positive correlation (r = 0.934, P = 0.020) with larval densities in Ajegunle only. Permanent mosquito-breeding habitats had significantly greater larval densities than temporary habitats within the slum communities. These findings could inform the development of integrated vector control strategies that address the different species of mosquitoes in the fight against MBDs in urban slums.

Laboratory and Field Culture of Larvae of The Slipper Limpet, Crepidula fornicata.

The calyptraeid gastropod mollusk, Crepidula fornicata, has been widely used for studies of larval developmental biology, physiology, and ecology. Brooded veliger larvae of this species were collected by siphoning onto a sieve after natural release by adults, distributed into the culture at a density of 200/L, and fed with Isochrysis galbana (strain T-ISO) at 1 x 105 cells/mL. Shell growth and acquisition of competence for metamorphosis were documented for sibling larvae reared in ventilated 800 mL cultures designed for equilibration to ambient air or to defined atmospheric gas mixtures. Contrasting with these laboratory culture conditions; growth and competence data were also collected for larvae reared in a 15 L flow-through ambient seawater mesocosm located in a field population of reproductive adults. Growth rates and timing of metamorphic competence in the laboratory cultures were similar to those reported in previously published studies. Larvae reared in the field mesocosm grew much faster and metamorphosed sooner than reported for any laboratory studies. Together, these methods are suited for exploring larval development under predetermined controlled conditions in the laboratory as well as under naturally occurring conditions in the field.

The outbreak of Drupella snails and its catastrophic effects on coral reefs: a comprehensive review

The recurring outbreaks of Drupella snails are a significant threat to coral reef ecosystems on a global scale. However, research on Drupella snails is currently very fragmentary. This article explores the ecological impacts and mitigation methods of Drupella snails and its outbreaks, and draws the following main conclusions. 1) Drupella snails inhabit the tropical oceans of the Indo-Pacific, utilizing their specialized radula to feed on coral polyps, and they predominantly spawn during summer, attaching egg capsules onto coral skeletons. 2) An outbreak of Drupella snails is defined by a density of &amp;gt; 2 ind/m2, but large aggregations alone do not necessarily indicate an outbreak. 3) The damage of coral reef ecosystem is the primary cause of Drupella snail outbreaks, with the hypotheses of “terrestrial nutrient input” and “overfishing of predator” being widely accepted but not fully explaining all outbreak events. 4) Countering Drupella snail outbreaks involves improving the health of coral reef ecosystems, protected areas, biological control and manual removal, though manual removal is the most direct and effective in short-term. 5) The understanding of the physiological and ecological characteristics of Drupella snails is inadequate at present, with larval development and population ecology being areas of particular under-investigation. 6) Studies of Drupella snail outbreaks have focused mainly on mid-outbreak stages, with little attention to early warnings beforehand or adverse outcomes afterwards. Despite significant challenges, addressing knowledge gaps in the biology of Drupella snails is crucial to determine the true causes of their outbreaks and identify corresponding solutions.

Feeding rates and carbon and nitrogen partitioning in crown-of-thorns sea star larvae (Acanthaster cf. solaris) during development

Crown-of-thorns sea star (CoTS; Acanthaster cf. solaris) outbreaks are a significant cause of coral decline. Enhanced food supply for the larvae via eutrophication is implicated as a cause of outbreaks, yet larval feeding ecology is poorly understood. In this study, feeding experiments were carried out at two algal food concentrations of 1000 cells mL−1 (~ 1.52 µg chl a L−1) and 3000 cells mL−1 (~ 4.56 µg chl a L−1) across six successive larval stages to investigate the effect of food concentration on filtration rate and ingestion rate for these stages. Filtration rate increased with larval stage and more than tripled from 127 ± 32 µL larva−1 h−1 (mean ± SE) of the youngest (2–3 dpf) larvae to 497 ± 109 µL larva−1 h−1 at late brachiolaria stage (9–10 dpf). Ingestion rate increased with food concentration and larval age, with advanced brachiolaria larvae consuming 313.5 ± 39.1 cells larva−1 h−1 in the higher algal food treatment. Organic carbon (C) and nitrogen (N) measured in larvae and their food indicated that the youngest feeding larvae ingested 13% their body carbon content daily, with that number almost doubling to 24% by advanced bipinnaria stage. The C/N ratio decreased sharply for brachiolaria larvae, reflecting developmental changes and greater dependence on exogenous nutrition. These results add to our understanding of the role food concentration plays in the growth and survivorship of CoTS larvae in the field.

Larval development of Argia joergenseni (Odonata: Coenagrionidae) at two different latitudes in Argentina

Our aim was to investigate the larval development of Argia joergenseni Ris in three streams located at different latitudes and ecoregions (Yungas and Chaco) in Argentina. We measured the head width and the metathoracic wing sheath length, and classified larvae into five size classes. Our results showed different patterns of larval growth between the three study sites. At the Yungas sites (latitude 26º S), larvae exhibited a high proportion of small individuals throughout the year, suggesting a multivoltine life cycle. In contrast, larvae in the Chaco region (latitude 32º S) showed marked seasonality in growth. The findings indicate a negative correlation between voltinism and latitude in A. joergenseni. The species exhibited an almost continuous flight season in the Yungas, while at the southern limit of its distribution (Chaco), the flight season was limited to the warmest months. This study provides important information on the larval ecology of A. joergenseni, contributing to a better understanding of the dynamics of damselfly communities and facilitating the development of effective conservation measures.

Determinants of Aedes mosquito larval ecology in a heterogeneous urban environment- a longitudinal study in Bengaluru, India.

Aedes-borne disease risk is associated with contemporary urbanization practices where city developing structures function as a catalyst for creating mosquito breeding habitats. We lack better understanding on how the links between landscape ecology and urban geography contribute to the prevalence and abundance of mosquito and pathogen spread. An outdoor longitudinal study in Bengaluru (Karnataka, India) was conducted between February 2021 and June 2022 to examine the effects of macrohabitat types on the diversity and distribution of larval habitats, mosquito species composition, and body size to quantify the risk of dengue outbreak in the landscape context. A total of 8,717 container breeding sites were inspected, of these 1,316 were wet breeding habitats. A total of 1,619 mosquito larvae representing 16 species from six macrohabitats and nine microhabitats were collected. Aedes aegypti and Aedes albopictus were the dominant species and significantly higher in artificial habitats than in natural habitats. Breeding preference ratio for Aedes species was high in grinding stones and storage containers. The Aedes infestation indices were higher than the WHO threshold and showed significant linear increase from Barren habitat to High density areas. We found Ae. albopictus breeding in sympatry with Ae. aegypti had shorter wing length. A large proportion of larval habitats were man-made artificial containers. Landscape ecology drives mosquito diversity and abundance even at a small spatial scale which could be affecting the localized outbreaks. Our findings showed that sampling strategies for mosquito surveillance must include urban environments with non-residential locations and dengue transmission reduction programmes should focus on 'neighbourhood surveillance' as well to prevent and control the rising threat of Aedes-borne diseases.

Impacts of artificial light at night on the early life history of two ecosystem engineers.

Sessile marine invertebrates play a vital role as ecosystem engineers and in benthic-pelagic coupling. Most benthic fauna develop through larval stages and the importance of natural light cycles for larval biology and ecology is long-established. Natural light-dark cycles regulate two of the largest ocean-scale processes that are fundamental to larvae's life cycle: the timing of broadcast spawning for successful fertilization and diel vertical migration for foraging and predator avoidance. Given the reliance on light and the ecological role of larvae, surprisingly little is known about the impacts of artificial light at night (ALAN) on the early life history of habitat-forming species. We quantified ALAN impacts on larval performance (survival, growth, development) of two cosmopolitan ecosystem engineers in temperate marine ecosystems, the mussel Mytilus edulis and the barnacle Austrominius modestus. Higher ALAN irradiance reduced survival in both species (57% and 13%, respectively). ALAN effects on development and growth were small overall, and different between species, time-points and parentage. Our results show that ALAN adversely affects larval survival and reiterates the importance of paternal influence on offspring performance. ALAN impacts on the early life stages of ecosystem engineering species have implications not only for population viability but also the ecological communities that these species support. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Characterization of Anopheles funestus Larval Habitats in Fiyoni, Kwale County, Kenya: Insights into Malaria Vector Ecology and Control

The breeding of malaria-spreading vectors such as Anopheles funestus is influenced by various environmental factors that contribute indirectly to the transmission of the Plasmodium parasite. However, there is limited knowledge of larval habitat ecology that hinder prevention and control of mosquito-borne diseases. This study aimed to characterize larval habitats based on physicochemical and habitat characteristics, considering the abundance of A. funestus. A cross-sectional survey method was used to collect data on the established transects. Physical parameters (water temperature, pH, conductivity, and total dissolved solids) were measured using a 5-in-1 meter probe. Levels of chemical parameters (sulphate, COD, and BOD) were determined in the laboratory using standard methods. Observations were also made on habitat characteristics (including watercolor, habitat size, and canopy). There was significant effect (P&lt;0.05) of conductivity, pH, sulphate, COD, and BOD on the number of A. funestus larvae. Water samples with a high population of A. funestus larvae were found to have higher conductivity (Me of 470.5), TDS (Me = 235), and pH levels (Me of 6.71). Conversely, water samples with a high population of non-Anopheles funestus larvae were found to have higher COD (Me of 843.20), BOD (Me of 367.2), and SO4 levels (Me of 11.3). A significant correlation (p&lt;0.5) existed between A. funestus larvae and physical water parameters. For instance, Anopheles funestus larvae was high (Me of 36.85) in stagnant water and in semi-permanent water (Me of 47.37). The study demonstrates that both physicochemical and habitat parameters significantly influence the abundance of Anopheles funestus larvae in larval habitats. Parameters such as conductivity, pH, total dissolved solids, sulphate, COD, BOD, watercolor, depth, distance from the homestead, and habitat size were found to be important in determining the presence of A. funestus larvae. Therefore, vector control strategies should include larval source management by targeting rivers and other water bodies to prevent the emergence of Anopheles funestus.

Eumasia venefica sp. nov. a new species of the subfamily Eumasiinae (Lepidoptera: Psychidae) from India with atypical larval ecology.

A new species of bagworm moth, Eumasia venefica sp. nov., from the subfamily Eumasiinae, is described from Kerala, India. This species has a peculiar larval ecology, larval case structure and an association with lichens. The paper describes the detailed taxonomy of the adult and the larval stages of the species.

SEASONAL AND HOST-ASSOCIATED VARIATION IN BOT FLY (OESTRIDAE: CUTEREBRINAE) PARASITISM OF LAGOMORPHS ACROSS AN ARID-LAND ECOSYSTEM IN SOUTHERN NEW MEXICO.

Bot flies (Oestridae: Cuterebrinae) are obligate mammalian parasites that complete the larval stage of their life cycle under the skin of their host. Most detailed studies of bot fly larval disease ecology have been conducted in temperate deciduous zone rodent systems. To understand the relative importance of seasonal and spatial factors, as well as factors intrinsic to the host, in underpinning the likelihood and extent of parasitism by bot flies in non-rodent hosts as well as in arid-land ecosystems, we examined the dynamic for black-tailed jackrabbit (Lepus californicus) and desert cottontail (Sylvilagus audubonii) parasitism by bot fly larvae (Cuterebra spp.) across 7 repeatedly sampled sites spread across approximately 500 km of the Chihuahuan Desert ecoregion of southern New Mexico. This environment is characterized by a climate that includes hot dry summers and cool to cold dry winters, as well as strongly seasonal summer monsoonal rains. Lagomorphs are a common mid-sized mammal in these landscapes. Bot fly parasitism was strongly seasonal, with peak prevalence and abundance in the spring, and there was spatial variation in the extent of parasitism between collection sites. Additionally, jackrabbits in better body condition were less likely to be parasitized (as indicated by kidney fat index). We did not find sex-based differences in bot fly parasitism between male and female jackrabbits. Thus, in arid-land ecoregions, abiotic factors are likely the primary driver of the bot fly-host interaction, whereas factors intrinsic to the host were of secondary importance for characterizing the interactions of bot flies and lagomorphs.

Ecology and diversity of mosquito larvae in ponds and lagoons of Northwestern Spain.

Galicia, located in the northwestern part of Spain,has a great number and variety of aquatic ecosystems where mosquitoes can breed. Despite the sanitary relevance of these insects, studies on mosquito populations in the region are still scarce. The field research was carried out in 48 sampling points (27 continental lagoons, 12 coastal lagoons and 9 temporary ponds) throughout the entire Galician territory. The samples were collected intermittently and seasonally through different water quality monitoring projects between 2001 and 2017. More than 1500 mosquito larvae belonging to 10 species of five genera (Aedes, Anopheles, Coquillettidia, Culex and Culiseta) were identified. Anopheles (Anopheles) maculipennis s.l. Meigen was the most widely distributed species in the study, being especially dominant in rural areas. In contrast, Culex (Culex) pipiens Linnaeus and Culex (Culex) theileri Theobald showed a preference for breeding in urban areas. New contributions to the knowledge about the larval ecology and distribution of these mosquito species are made throughout this study, including information about the tolerance of each species to water parameters (temperature, pH, dissolved oxygen and conductivity). Likewise, the relationship between culicid diversity and the habitat characteristics of the breeding sites (water body type, climate and level of anthropization) is discussed.

One genus, four different stories: evolutionary history, bionomics and biogeography of the monotypic tribe Stenostomatini (Coleoptera: Oedemeridae)

Abstract The false blister beetle tribe Stenostomatini includes only the genus Stenostoma, with four species showing an intriguing distribution: Stenostoma lowei (Madeira), Stenostoma cossyrense (Pantelleria), Stenostoma melitense (Malta and southern Sicily) and Stenostoma rostratum, widely distributed along the Mediterranean and North Atlantic coasts. The evolutionary history leading to this distribution has not been investigated. Here, we explore the phylogeny and evolutionary history of the tribe, adopting an integrative approach that combines morphological and molecular data (mitochondrial COI and nuclear CAD and 28S). Moreover, we propose a new key for species identification and update the knowledge on adult and larval ecology. Finally, we propose the following explanation for the current distribution of the species. The genus originated in the Miocene, with S. lowei belonging to the oldest lineage. The remaining species share a common ancestor, dating to the Messinian Salinity Crisis. Stenostoma melitense and S. cossyrense are well differentiated according to morphology, but not according to molecular analysis. The wide distribution of S. rostratum might be related to its strategy of laying eggs within beached driftwood, where larvae develop, easily transported by the currents. Given that neither morphological nor molecular differentiation was detected between the two subspecies of S. rostratum, we propose the new synonymy Stenostoma rostratum septentrionaleŠvihla, 2005 = Stenostoma rostratum (Fabricius, 1787) syn. nov.

Effects of elevated temperatures and health status of the crustose coralline algae Hydrolithon boergesenii (Corallinales: Mastophoroideae) on the larval settlement of Diploria labyrinthiformis (Scleractinia: Faviinae)

Crustose Coralline Algae (CCA) is a well-known settlement inducer for stony corals and vital for successful recruitment, reef growth and resilience. However, potential impacts of diseased CCA on larval settlement are not fully understood, especially on particular coral species. As oceans continue to warm, coral larvae need to be able to respond to settlement cues amid elevated temperatures, yet the combined effects of thermal stress and CCA health status on larval behavior is not well known for most coral species. Here, we assessed the effect of elevated temperatures and health status on the ability of the CCA Hydrolithon boergesenii to induce settlement of coral Diploria labyrinthiformis larvae. D. labyrinthiformis planulae were exposed to 4 substrate combinations (healthy CCA, diseased CCA, bare substratum, and bare tissue culture plate) and three temperatures (27.5 °C, 29 °C, and 31 °C). Overall, settlement started earlier and was 1.5-3x higher at 31 °C, regardless of CCA health status, but at this temperature, larval mortality increased two-fold in diseased CCA. Settlement differences between healthy and diseased H. boergesenii were only observed at 29 °C, with healthy CCA facilitating twice as much settlement and having 3x lower mortality than diseased. Our findings suggest that, even though larvae can settle in both healthy and diseased CCA, temperature plays an important role in whether larvae will settle or perish. This study highlights the importance of healthy CCA to maintain and increase settlement and the ability of larvae to adapt to a warming ocean, contributing to the knowledge of D. labyrinthiformis larval ecology, valuable for larval rearing for restoration purposes.

Sensitivity to life-history parameters in larval fish drift modelling predictions for contrasting climatic conditions

Many marine fish species display a long larval drift between offshore spawning grounds and coastal nursery areas. This drift, whose efficiency drive the renewal of the population, critically depends on many environmental factors and on the spawning behaviour of species. Given the complexity to collect field data on fishes early life stages, modelling has proved to be one of the most valuable tool to explore such questions. However, these complex models require many parameters, many of which are uncertain, making a comprehensive sensitivity analysis a crucial step before drawing conclusions on the effects of environmental drivers. This study focused on the larval drift of five species archetypes mimicking five commercially important fish species with contrasted spawning strategies and larval ecology, in five different sub regions over Western Europe, from the Iberian coast to the North Sea. Using an hydrodynamic model (MARS3D) coupled with an individual-based model, and by building a simulation design suitable for such sensitivity analysis, we assessed the relative influence of extrinsic (years and region’s hydrodynamics) and intrinsic (spawning grounds’ depth, spawning period, vertical migration, developmental rate, daily mortality and tolerance to temperature) factors and their two-ways interactions on recruitment success to nurseries. The thermal tolerance of species was one of the leading factors, suggesting that this is a critical parameter, especially when modelling species recruitment success at the edge of their distribution range. On the other hand, other parameters such as the nycthemeral vertical migration, that are often discussed in such larval drift simulation exercise, have proved to have a more limited influence for an analysis at such a large spatial scale. Overall, when studying larval drift on a large scale, local hydrodynamics and inter-annual variations hold most of the explained variance in the recruitment success, confirming the importance of repeating simulations over multiple years before exploring the connectivity among spawning and nursery areas.

&lt;i&gt;Chrysoritis&lt;/i&gt; Butler (Papilionoidea: Lycaenidae: Aphnaeinae) – Part II: Natural history: morphology, ecology, and behaviour, with accounts of larval ecology and insights into the aphytophagous &lt;i&gt;C. dicksoni&lt;/i&gt; (Gabriel)

The natural history, morphology, ecology, and behaviour of adults and juveniles of Chrysoritis, and their larval associations with host ants, are described in detail, including insights into the aphytophagous species C. dicksoni.

Impact of anthropogenic sounds (pile driving, drilling and vessels) on the development of model species involved in marine biofouling

The uncontrolled colonization of benthic organisms on submerged surfaces, also called biofouling, causes severe damage in the shipping and aquaculture industries. Biofouling starts with a benthic biofilm composed of a complex assemblage of microbes, bacteria and benthic diatoms, called microfouling, on which macrofouling invertebrate species settle and grow. Invertebrate larvae may use natural soundscapes to orientate inshore and choose their optimal habitat. Recent studies have demonstrated that ship sounds enhance the larval settlement and growth of several invertebrate species, such as mussels, associated with biofouling. Among invertebrates, effects of sound generated by offshore human activities are still poorly studied. This study aims to assess the effect of pile driving, drilling and vessel sounds on model species associated with micro and macrofouling. First, the biofilm development of Navicula pelliculosa and Amphora coffeaeformis was assessed, then, the larval development of the blue mussel (Mytilus edulis) was evaluated from the D-veliger to the postlarval stage. Mussel larvae and microalgae were exposed 12 h each day in tanks (Larvosonic) adapted to sound experiments under controlled conditions. All anthropogenic sounds induced a thinner N. pelliculosa biofilm coupled with a lower microalgae concentration. The drilling sound had a stronger effect on the biofilm thickness. The drilling sound significantly reduced the pediveliger settlement and the postlarvae clearance rate by 70.4% and tended to diminish settler sizes compared to control sound. Contrary to our expectation, pile driving tended to enhance larval recruitment by 22% (P=0.077) and the boat sound did not stimulate larval settlements or recruitment. Drilling sound generated a stressful acoustic environment for pediveliger settlements and postlarvae seem to maintain their shell valves closed to preserve energy. We identify potential causes and mechanisms involved in these impacts of anthropophony on larval ecology and microfouling dynamics.

Parasite control in regenerative livestock farming

Advocates of regenerative livestock farming claim a multitude of benefits following adoption of practices based on high intensity, short duration, long rest rotational grazing, amongst which is a reduction in parasitism and the use of anthelmintics. There are limited scientific data to support such claims and much of what little evidence there is emanates from North America and South Africa, so it would be useful if the observations and experiences of UK adoptees could be backed up with some well-controlled field studies. In their absence, considerations of some aspects of known parasite biology, such as the larval ecology of parasitic nematodes, can shed light on likely outcomes of various types of pasture, grazing and animal management. Minimising the use of anthelmintics in regenerative systems requires effective monitoring to ensure that animal performance and health do not suffer as a result of parasitism; for youngstock, growth rate is the most reliable marker for subclinical parasitic gastroenteritis. Consideration should also be given to other parasites that can affect grazing livestock, such as lungworm, fluke, ticks and flies, in order to determine the influence of regenerative management on the parasite fauna and their collective impact on sheep and cattle.