Seasonal Life Cycle Research Articles

Distribution and life cycles of mayflies Andesiops torrens (Lugo-Ortiz and McCafferty, 1999) and Andesiops peruvianus (Ulmer, 1920) (Ephemeroptera: Baetidae): importance for environmental monitoring

Streams are suffering multiple disturbances worldwide, directly threatening biodiversity. Studying species in minimally disturbed streams will help to understand ecological patterns before they are altered by humans. The distribution and life cycles of the mayflies Andesiops torrens (Lugo-Ortiz and McCafferty, 1999) and Andesiops peruvianus (Ulmer, 1920) were investigated in a perennial Mediterranean coastal stream of Chile (Nonguén) from September, 2017 to August, 2018. Andesiops peruvianus had higher abundance throughout the year with 29.6 to 1117.4 ind/m2, whereas A. torrens had from 33.3 to 481ind/m2. Both species have a univoltine seasonal life cycle, with emergence in late winter and early spring; A. torrens larvae mature from September to October, and A. peruvianus larvae from August to October. A significant correlation was found between density of species and water temperature, precipitation, water velocity and discharge. Our data found some differences in emergence periods compared to previous studies on both species in other streams from South America. We report on the species distribution and argue the importance of life cycles in freshwater biomonitoring, highlighting the biological traits of Andesiops Lugo-Ortiz and McCafferty, 1999 that could prove useful for biomonitoring purposes.

Molecular evidence reveals fish-pathogenic Aphanomyces spp. (Oomycetes: Saprolegniales) on new host of the threatened seasonal cyprinodont fish Nothobranchius spp. (Teleostei: Cyprinodontiformes) in south-eastern Democratic Republic of Congo

The Aphanomyces species pose an important global threat and cause damage to aquaculture and agriculture by infecting aquatic animals and plants. Several subpopulations of the seasonal cyprinodont fish genus Nothobranchius with lesions suggestive of infection with Aphanomyces invadans, were observed in ephemeral wetland habitats of the upper Congo drainage in the south-eastern Democratic Republic of Congo. Molecular analyses on samples collected in 2023 revealed evidence of fish-pathogenic oomycetes Aphanomyces invadans and A. laevis, for the first time in the host of fish genus Nothobranchius spp. All Nothobranchius fishes in the upper Congo drainage are subject to a high level of threat and belong to one of the threatened Red List categories, due to habitat degradation of seasonal wetlands. These fishes complete their seasonal life cycle in ephemeral natural habitats. The latter makes them highly vulnerable, as such wetland habitats are often degraded by the cumulative effect of multiple human stressors which include: the cultivation of wetlands for agriculture, the abstraction of water, the expansion of urban areas and the pollution load. Evidence of infection by oomycete pathogens documented in this study, represents a critical additional threat to the unique seasonal aquatic biodiversity of the region.

Variability in spruce beetle (Coleoptera: Curculionidae, Scolytinae) adult diapause and evidence for oocyte development prior to winter in a Colorado population.

Diapause regulates seasonal insect life cycles and may be highly variable within and among populations due to genetic and environmental variability. Both types of variation may influence how populations respond plastically or evolutionarily to changing climates. We assessed diapause variability in spruce beetle Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae, Scolytinae), a major forest pest whose life cycle timing is regulated by both prepupal and adult diapauses. Using mating studies and ovary dissections, we tested for variability in adult diapause within and between collection sites in Colorado and Wyoming, USA. Ovary morphology suggested that most females from both sites enter diapause prior to egg formation (oogenesis) when reared at warm temperatures. Though previous studies suggested that adult diapause is obligate, we found that a small proportion of females from both populations terminated diapause without winter chilling in the lab. Moreover, we found that most female beetles sampled at the Colorado field site had mature ovaries relatively early in the fall, suggesting that transient exposure to low temperatures may potentiate pre-winter reproductive development. Adult diapause may act primarily as a block to prevent offspring production late in the season but not necessarily as an overwintering phenotype. Overall, our data do not suggest imminent life cycle shifts mediated by adult diapause, but if the observed variability is heritable, diapause regulation may evolve in response to changing environmental conditions.

Wild black soldier flies, Hermetia illucens (Diptera: Stratiomyidae): Seasonal availability and life history traits in two common organic streams in Bangladesh

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) is a “crown jewel” in waste management because it rapidly bioconverts organic streams into nutrient-rich biomass. Bangladesh's inefficient waste management has caused serious environmental issues due to the massive amounts of organic waste, mainly livestock manures and municipal organic waste, generated daily. We need reliable BSF to maximize our organic resources. To establish a long-term, stable BSF colony, we closely examined the seasonal abundance and life cycle features of BSF raised on municipal garbage and poultry manure in a regional natural environment in the lab. This investigation lasted two years (2019–2020). Season and raising substrates affected wild BSF egg clutches and life cycles. Organic waste dumps captured the most egg clutches in rainy seasons and the fewest in cooler months. Municipal rubbish dumps consistently produced wilder BSF egg clutches than poultry manure dumpsites. The BSF larvae grew slower in winter and faster in the rainy season, independent of substrate. Winter was optimal for adult BSF longevity in all organic streams. Winter cultivated wild BSF on two organic streams exhibited fewer egg clutches per female, shorter and lighter prepupae, and lower adult ecolosion rates than wetter months. While BSF given municipal organic wastes had the highest adult ecolosion rates, BSF fed poultry manure had more variation in prepupae length and weight, adult lifespan, and egg clutches. Larval development was faster with poultry manure BSF than with municipal organic waste. The protein and ash content of prepupae rearing on poultry manure exceeded those of prepupae on urban organic waste, although fat content was equivalent. These findings indicate that both types of organic streams may be suitable substrates for BSF larvae for trash treatment.

An independent origin of an annual life cycle in a North American killifish species

Abstract An annual life cycle is characterized by short-lived adults that exploit seasonally productive but temporary habitats, paired with a hardy embryo stage that survives unfavourable environmental conditions, such as winter or the dry season. This life cycle is rare amongst vertebrates but has evolved independently several times in African and South American killifishes adapted to life in seasonally ephemeral aquatic pools. A single species of North American annual killifish, with a limited geographical distribution in Mexico, also exhibits this seasonal life cycle. This enigmatic species, Millerichthys robustus, is geographically separated from the nearest South American annual killifish species by >2000 km. Millerichthys robustus exhibits morphological features that have led to several competing phylogenetic hypotheses. To date, its phylogenetic relationships are unclear because no molecular data have been available. Here, we sequence the mitochondrial genome of Millerichthys robustus and generate a molecular phylogeny of killifishes that includes this species. Our results indicate that, rather than being most closely related to South American annual killifishes, this species is sister to two non-annual killifish species from Cuba (Rivulus cylindraceus and Rivulus berovidesi). Ancestral state reconstruction strongly supports an independent origin of an annual life cycle and embryonic diapause in Millerichthys robustus.

Life cycle and seasonal regulation of Onychogomphus forcipatus unguiculatus in the Seybouse River, Algeria (Insecta: Odonata)

Understanding the seasonal regulation and life cycle patterns of Odonata is critical to identifying the factors that influence their voltinism. While the life history and seasonal regulation of Odonata, particularly gomphids, has been studied extensively, few studies have focused on North African gomphids. This study aims to contribute to the understanding of the life cycle of Onychogomphus forcipatus unguiculatus (Vander Linden, 1823), a western Mediterranean gomphid, on the Seybouse River in northeastern Algeria and discuss its seasonal regulation. Our results imply that a generation of O. f. unguiculatus requires two years to develop. The appearance of small (F-6) larvae in early spring can be attributed to the hatching of eggs in the previous year, followed by their overwintering in interstitial habitats. This abrupt appearance of small larvae is the result of their unique life history strategy of developing and surviving in specialized habitats during winter, then continuously growing and developing. The senior cohort overlaps with its junior counterpart, overwintering primarily in instars F-1, F-2, and, to a lesser extent, F-3, before beginning to emerge in late spring and early summer. By examining the voltinism and life cycle patterns of O. f. unguiculatus, this study contributes to our understanding of the reproductive strategies and population dynamics of this western Mediterranean gomphid, as well as of factors affecting the phenology and ecology of Odonata, particularly in North Africa, and in this manner contributes to overall efforts to protect and manage freshwater ecosystems in this region.

Asynchronous contributions of decapod life history stages to the zooplankton of tropical estuarine, coastal and shelf ecosystems - new insights from semi-automatic image analysis

Decapod crustaceans include many species of socioeconomic importance and are key components of pelagic ecosystems, both as adults and as larval forms. Knowledge on seasonal and spatial synchronicity of planktonic larvae in coastal tropical ecosystems is fundamental to understand the dynamics of these complex ecosystems. The objective of the present study was to quantify the contributions of decapods to the zooplankton in adjacent tropical estuarine, coastal and shelf ecosystems, while considering their seasonal life cycles and probable dispersal strategies. We evaluated the contributions of decapod biomass and biovolume in three distinct ecosystems: Rio Formoso estuary, Tamandaré bay, and Pernambuco continental shelf off Tamandaré, northeastern Brazil. Zooplankton samples were taken bimonthly from June 2013 to May 2015, with a 300 μm mesh net, and analyzed using a ZooScan equipment. Decapods were the second most important organisms (after copepods), in abundance, biomass and biovolume, in all sampling areas. Total decapods contributed on average with 33.6%, 4.4% and 7.1% relative abundance and 30.9%, 30.9%, and 15.2% relative biovolume in estuary, bay, and shelf areas, respectively. Overall, the most relevant decapod taxa and stages found in the three sampling areas were brachyuran crab zoeae and megalopae, penaeid shrimp postlarvae (mostly Penaeus spp.), holoplanktonic luciferids (adults, protozoeae and mysis), anomuran zoeae (mostly Paguridae and Diogenidae hermit crabs), pistol shrimp zoeae (Alpheidae), and porcelain crab zoeae (Porcellanidae). Brachyuran zoeae contributed with up to 81.3% abundance and up to 69% biovolume, in the estuary. Penaeid postlarvae comprised up to 28.1% of total abundance and up to 94.7% of total biovolume, on the shelf. These postlarvae were transported shorewards from the offshore shelf. Decapod contributions were especially relevant during massive larval release events of crab zoeae and during shoreward migration of pre-settlement stages. Seasonal peaks were clearly asynchronous between taxa and areas. Possible functional relationships between copepods and key decapod groups are discussed, as well as the processes triggering and regulating the input of larvae. Our results show the importance of quantitative, semi-automatic approaches and the relevance of decapod larvae for pelagic food webs in tropical coastal areas.

Discovery of an underground chamber to protect kings and queens during winter in temperate termites

Overwintering is a critical part of the annual cycle for species that live in temperate, polar, and alpine regions. Consequently, low-temperature biology is a key determinant of temperate species distribution. Termites are distributed predominantly in tropical regions, and a limited number of species are found in the temperate zone. Here, in the termite Reticulitermes speratus, we report the discovery of an underground chamber that protects kings and queens to survive the winter, which is separate from the one they used during the warmer breeding season. In the spring, the royals inhabited decayed logs on the ground, then moved to their underground chamber located in the roots of stumps in the fall. The winter minimum temperature measured in the royal chamber was higher than that in the logs on the ground. In overwintering termites, the kings and queens had higher cold tolerance than workers and soldiers. Air temperatures dropped below the critical temperature multiple times, as evidenced from the past 140 years of weather records in Kyoto. These results demonstrated the survival strategies of reproductives to overcome the environment at the latitudinal limits. This study helps further the understanding of the termite’s seasonal phenology, long-term survivorship, and life cycle.

How do host plant use and seasonal life cycle relate to insect body size: A case study on European geometrid moths (Lepidoptera: Geometridae).

We used European geometrid moths (>630 species) as a model group to investigate how life history traits linked to larval host plant use (i.e., diet breadth and host-plant growth form) and seasonal life cycle (i.e., voltinism, overwintering stage and caterpillar phenology) are related to adult body size in holometabolous insect herbivores. To do so, we applied phylogenetic comparative methods to account for shared evolutionary history among herbivore species. We further categorized larval diet breadth based on the phylogenetic structure of utilized host plant genera. Our results indicate that species associated with woody plants are, on average, larger than herb feeders and increase in size with increasing diet breadth. Obligatorily univoltine species are larger than multivoltine species, and attain larger sizes when their larvae occur exclusively in the early season. Furthermore, the adult body size is significantly smaller in species that overwinter in the pupal stage compared to those that overwinter as eggs or caterpillars. In summary, our results indicate that the ecological niche of holometabolous insect herbivores is strongly interrelated with body size at maturity.

Altitudinal distribution and seasonal life cycle of drosophilid flies (Diptera: Drosophilidae) in central Japan, with reference to their biogeographic features

AbstractAltitudinal distribution and seasonal life cycle of drosophilid flies (Diptera) were studied on the southwestern slope of Mt. Higashi‐Kagonoto in Tomi and at Ishi‐no‐yu in Shiga Heights, Nagano, central Japan. Collections of flies were carried out from early spring to late autumn using traps baited with fermenting banana. Based on the present results and previous faunal reports from central Japan, major native drosophilid species collected in this study were classified into migratory (5 species), high‐altitude (6), mid‐altitude (14) and low‐altitude (14) species. The migratory species are assumed to perform extensive seasonal migration between low‐ and high‐altitude areas. Among these native species, Drosophila alpina (a high‐altitude species) and D. moriwakii (a mid‐altitude species) are assumed to pass only one generation in a year, while the others pass two or more generations. Five of the six high‐altitude species are assigned as the Palearctic elements, while four of the five migratory species and 12 of the 14 low‐altitude species are assigned as the Sino‐Japanese elements. The mid‐altitude species consist of approximately equal numbers of the Palearctic and Sino‐Japanese elements. Among the high‐altitude species, D. alpina and Hirtodrosophila makinoi are also distributed in high‐altitude areas in Hokkaido, northern Japan. The other high‐altitude species and most of the mid‐altitude species generally occur in low‐altitude areas in Hokkaido or the further north. The Sino‐Japanese elements occurring at high and mid altitudes in central Japan are also distributed at high altitudes in southern and southwestern China.

Observations on growth rate and allometry in the seasonal predatory killifish Nothobranchius ocellatus (Teleostei: Cyprinodontiformes).

During the course of a taxonomic study involving Nothobranchius ocellatus, a fast-growing seasonal killifish of predatory behaviour, important morphometric differences were observed between the original measurements of the lost holotype and the neotype and additional available material of the species. In a laboratory study, the total length (TL) of selected specimens was measured from hatching and, during the sub-adult to sexually mature young adult phase, from 37 to 84 days age, subjected to an additional suite of detailed morphometric measurements. Growth rate was relatively rapid and linear at 1.31.4 mm/day through the first phase to sexual maturity at 78 weeks, followed by a marked flattening of the growth curve with, from 14 weeks, rates of only about 1.0 mm/week in males and 0.6 mm/week in females. Under captive conditions, maximum TL for adult male specimens ranged from 101 to 116 mm and 88 to 102 mm for females. Analyses of the morphometric character measurements made during the 3784 day development phase showed allometric shape changes, primarily seen in body depth, head length and several other measures of head features, proportions of caudal peduncle, and length of fin bases. These changes are most prominently seen in males and changes in head proportions are important in relation to the predatory behaviour of the species. Morphometric differences between the immature holotype and the newly available material, including the neotype, are consistent with allometric shape variation, particularly in males of this species. Considering the seasonal life cycle common to all Nothobranchius species, and similar growth patterns, it is likely that allometric growth has broad relevance within the genus, suggesting it is a factor that should be taken into account in taxonomic endeavours, especially when the number of study specimens is limited.

Sugars and the speed of life-Metabolic signals that determine plant growth, development and death.

Plant growth and development depend on the availability of carbohydrates synthesised in photosynthesis (source activity) and utilisation of these carbohydrates for growth (sink activity). External conditions, such as temperature, nutrient availability and stress, can affect source as well as sink activity. Optimal utilisation of resources is under circadian clock control. This molecular timekeeper ensures that growth responses are adjusted to different photoperiod and temperature settings by modulating starch accumulation and degradation accordingly. For example, during the night, starch degradation is required to provide sugars for growth. Under favourable growth conditions, high sugar availability stimulates growth and development, resulting in an overall accelerated life cycle of annual plants. Key signalling components include trehalose‐6‐phosphate (Tre6P), which reflects sucrose availability and stimulates growth and branching when the conditions are favourable. Under sink limitation, Tre6P does, however, inhibit night‐time starch degradation. Tre6P interacts with Sucrose‐non‐fermenting1‐Related Kinase1 (SnRK1), a protein kinase that inhibits growth under starvation and stress conditions and delays development (including flowering and senescence). Tre6P inhibits SnRK1 activity, but SnRK1 increases the Tre6P to sucrose ratio under favourable conditions. Alongside Tre6P, Target of Rapamycin (TOR) stimulates processes such as protein synthesis and growth when sugar availability is high. In annual plants, an accelerated life cycle results in early leaf and plant senescence, thus shortening the lifespan. While the availability of carbohydrates in the form of sucrose and other sugars also plays an important role in seasonal life cycle events (phenology) of perennial plants, the sugar signalling pathways in perennials are less well understood.

Seasonal patterns of growth, alginate content and block structure of the alien invader Sargassum muticum (Fucales, Ochrophyta) from the Atlantic coast of Morocco

Abstract In the present study, alginate yield and composition were investigated during the seasonal life cycle of the alien brown alga Sargassum muticum harvested from the Atlantic coast of Morocco. Alginate yield ranged from 11.14% in winter to 25.62% in spring/early summer, coinciding with maximum vegetative growth. Monthly monitoring of the alginate block structure showed that the highest mannuronate (M)/guluronate (G) ratio was recorded during the maximum development of S. muticum, before sexual maturity and during resumption of vegetative growth, giving maximum flexibility to the alga. The unusually high molar monad fractions (FG) and dyad fractions (FGG) of guluronic acid in late summer/early autumn appeared to be related to stiffness of senescent thalli. Rheological characterisation showed that the alginate of S. muticum exhibited pseudoplastic behaviour, with the highest apparent viscosities measured in late summer/early autumn when the G blocks dominated the alginate structure. This study suggests that S. muticum could be exploited as an alginophyte for commercial applications. The best harvest time is May-June, which corresponds to the highest alginate yield, maximum thallus growth, and largely completed sexual reproduction, ensuring sustainable exploitation of the species.

A review of the conservation status of seasonal Nothobranchius fishes (Teleostei: Cyprinodontiformes), a genus with a high level of threat, inhabiting ephemeral wetland habitats in Africa

Abstract The small and colourful Nothobranchius fishes inhabit ephemeral habitats in freshwater wetlands of Africa and have extreme life‐history adaptations that allow their eggs to survive the periodic drying up of the seasonal natural habitats. They are subject to high levels of threat, with 72% of the 94 assessed species falling into one of the threatened Red List categories, as a consequence of habitat degradation of seasonal wetlands. There is, therefore, a need to conserve ephemeral waters for species that rely on the seasonality of habitats. Extinction risk factors for all species of the genus were entirely reworked with IUCN Red List assessments, whereas first‐time assessments were established for species that had previously not been evaluated. These fishes complete their seasonal life cycle in ephemeral natural habitats and this makes them highly vulnerable, as such wetland habitats are often degraded owing to multiple interacting human‐induced stressors and threats, including cultivation of wetlands for agriculture, abstraction of water, expansion of urban areas and pollution load. A fine‐scale classification scheme based on habitat type was used for each site to identify ecological characteristics and the pattern of threats. The classification scheme is based on a primary subdivision of natural habitats compared with those modified by human activities, with further subdivision within the two fundamental groupings. Out of the 478 analysed habitat site observations by the authors, 46% were affected by human activities. Recommended conservation actions include: conducting surveys to better understand habitat trends and threats; establishing protected areas and effectively allocating resources to preserve wetland habitats; managing protection of the structural integrity of the habitats throughout the seasonal phases of wet and dry seasons; and raising awareness of the importance of healthy wetland systems and the value of the unique seasonal freshwater biodiversity.

Supporting an Expert-centric Process of New Product Introduction With Statistical Machine Learning

Industries that sell products with short-term or seasonal life cycles must regularly introduce new products. Forecasting the demand for New Product Introduction (NPI) can be challenging due to the fluctuations of many factors such as trend, seasonality, or other external and unpredictable phenomena (e.g., COVID-19 pandemic). Traditionally, NPI is an expertcentric process. This paper presents a study on automating the forecast of NPI demands using statistical Machine Learning (namely, Gradient Boosting and XGBoost). We show how to overcome shortcomings of the traditional data preparation that underpins the manual process. Moreover, we illustrate the role of cross-validation techniques for the hyper-parameter tuning and the validation of the models. Finally, we provide empirical evidence that statistical Machine Learning can forecast NPI demand better than experts.

A Novel Approach of Intermittent Demand Prediction in Industrial Domain

Intermittent demand, one of the categories of unusual demand, such as demand of spare parts of industry equipment management, seasonal and short life cycle products, is characterized by infrequent demand arrivals and variable demand sizes, which is difficult to predict. To solve this problem, a novel approach was proposed in this paper to predict intermittent demand. It provided mechanism to forecast demand arrival time with demand values at the same time when demand occurs. It firstly applied Decision Tree to predict a 0-1 binary values of demand arrival time. Meanwhile Neural Network was built to predict demand values. Then the time points of these two results were matched. The demand values for those moments when predicted demand that did not occur were replaced by zero. Finally we applied this approach to predict sparse demand of products, the results showed that the predicting accuracy was superior to traditional Back-propagation Neural Network through comparison.

A Review of Trimen’s False Tiger Moth, Agoma trimenii (Lepidoptera: Agaristidae): Seasonal Biology, Potential Monitoring and Control Techniques

Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has recently been found to occur in vineyards in the Northern Cape and Limpopo (Groblersdal area) provinces of South Africa. As little is known about the biology and behaviour of the moth, no official monitoring methods or economic thresholds relating to it, exist. Consequently, management and registered control options still require development. The first aim in the current review, was to gather and critically discuss all the available information on A. trimenii in the context of the information gained from field observations conducted in the Northern Cape, South Africa, during the 2016/2017 and 2017/2018 seasons. The paper also includes reporting on field observations made with regard to various aspects of the seasonal life cycle and ecology of A . trimenii , with a view to investigate, in future research, the potential biological control options available. Potential monitoring strategies of A. trimenii in the field were investigated. Various life stages of A. trimenii were identified, peak flight times were established, overlapping generations were determined, and the behavioural traits of all life stages were documented. Ultraviolet blue light traps proved to be the most promising potential monitoring strategy, with the prospect for an A. trimenii pheromone lure holding potential as an alternative monitoring strategy in future. With summarising all current information on A. trimenii , recommendations for growers to monitor and control A. trimenii are presented, towards the development of an integrated pest management system for the moth.

Seasonal energy performance characteristics of novel ejector-expansion air conditioners with low-GWP refrigerants

The objective of this study is to investigate the seasonal performance characteristics of novel ejector-expansion air conditioners (EEACs) with low global warming potential refrigerants. A simplified simulation model for EEACs is developed and validated using measured data. Using a simulation model, the coefficient of performance, cooling seasonal performance factor, and life cycle climate performance of the EEACs employing low global warming potential refrigerants are analyzed at various operating conditions and modes. In addition, the climatic effects on the cooling seasonal performance factors and life cycle climate performances of the EEACs are evaluated at four different weather conditions. The EEAC with R290 exhibits the cooling seasonal performance factor and total CO2 emissions that are 22% higher and 23.3% lower, respectively, than those of the baseline air conditioner with R410A. In general, R290 is the best working fluid for EEACs in terms of the seasonal performance and lifetime environmental factor.

Seasonal gene expression profiling of Antarctic krill in three different latitudinal regions.

The Antarctic krill, Euphausia superba, has evolved seasonal rhythms of physiology and behaviour to survive under the extreme photoperiodic conditions in the Southern Ocean. However, the molecular mechanisms generating these rhythms remain far from understood. The aim of this study was to investigate seasonal differences in gene expression in three different latitudinal regions (South Georgia, South Orkneys/Bransfield Strait, Lazarev Sea) and to identify genes with potential regulatory roles in the seasonal life cycle of Antarctic krill. The RNA-seq data were analysed (a) for seasonal differences between summer and winter krill sampled from each region, and (b) for regional differences within each season. A large majority of genes showed an up-regulation in summer krill in all regions with respect to winter krill. However, seasonal differences in gene expression were less pronounced in Antarctic krill from South Georgia, most likely due to the milder seasonal conditions of the lower latitudes of this region, with a less extreme light regime and food availability between summer and winter. Our results suggest that in the South Orkneys/Bransfield Strait and Lazarev Sea region, Antarctic krill entered a state of metabolic depression and regressed development (winter quiescence) in winter. Moreover, seasonal gene expression signatures seem to be driven by a photoperiodic timing system that may adapt the flexible behaviour and physiology of Antarctic krill to the highly seasonal environment according to the latitudinal region. However, at the lower latitude South Georgia region, food availability might represent the main environmental cue influencing seasonal physiology.

Botrylloides crystallinus n. sp., a new Botryllinae Adams & Adams, 1858 (Ascidiacea) from Mediterranean Sea

Botrylloides crystallinus n. sp., collected on sublittoral hard substrata in North Mediterranean Sea is here described. The species presents a seasonal life cycle with a spring-summer regression of the zooids and their buds as known in the congeneric species B. leachii (Savigny, 1816), from which however differs in many unusual morphological traits.