Comparative description of the beaks of Chiroteuthis (cf) veranyi Férussac, 1835, Liocranchia reinhardti Steenstrup, 856, and Doryteuthis opalescens Berry, 1911 paralarvae (Cephalopoda: Teuthoidea)

Resumo: Estudos sobre o desenvolvimento morfológico do bico nos estágios iniciais do ciclo de vida de um cefalópode podem aumentar o conhecimento sobre a ecologia de paralarvas, mas são raros na literatura. No presente trabalho foram examinados bicos de 18, 16 e 31 paralarvas de Chiroteuthis cf. veranyi (3,62 a 13,62 mm comprimento do manto (CM)), Liocranchia reinhardti (2,80 a 20,63 mm CM) e Doryteuthis opalescens (2,25 a 12,30 mm CM), respectivamente. As estruturas das mandíbulas superior (MS) e inferior (MI) foram medidas e os valores foram comparados ao CM por regressão linear múltipla, de forma a determinar as influências relativas de cada uma no crescimento. Cada estrutura foi comparada entre espécies através de ANOVA para detectar possíveis diferenças. As mandíbulas apresentaram diferentes níveis de desenvolvimento e mudanças marcadas puderam ser observadas em CM distintos. Coloração foi observada principalmente em L. reinhardti e em D. opalescens. As paredes laterais e capuz (MS) e asas e paredes laterais (MI) foram as estruturas mais robustas, com uma importância significativa também do rostro (MI) para L. reinhardti. Dentes (MI) e uma fenda no rostro, características de cefalópodes ancestrais, foram observados em todas as espécies. Essas estruturas desapareceram total e parcialmente (fenda persistente) nos maiores indivíduos de L. reinhardti e D. opalescens, respectivamente, e foram retidas em todos os indivíduos analisados de C. cf. veranyi. Os resultados deste estudo revelam informações importantes sobre a morfologia funcional do bico durante os primeiros estágios do ciclo de vida de um cefalópode

Zooplankton performance in a changing ocean : adaptive capacities to a shifting food regime in the North Sea

Zooplanktonic organisms are often vulnerable to fluctuations in food supply. Their population dynamics is directly influenced by changes in phytoplankton availability and nutritional quality, which in turn is affected by changes in parameters such as nutrient loading. The aim of this study was to investigate how nitrogen (N) limitation in prey (i.e., food quality) affects the performance of zooplankton. Females of the copepod Temora longicornis and larvae of the polychaete Lanice conchilega were sampled in May and June 2016 off the German island of Helgoland, in the southern North Sea, for five-day laboratory feeding experiments. They were fed with diets of different quality - diatoms and dinoflagellates cultured in nutrient-replete (Diat and Dino , respectively) and in N-depleted (Diata and Dinoa , respectively) conditions. Sodium bicarbonate enriched with the 13C isotope (NaH13CO3) was added to prey cultures in order to label dietary fatty acids (FA) and to follow carbon (C) transfer into copepods and polychaetes. Zooplankton performance was assessed by analysis of the elemental and biochemical compositions and of the assimilation and turnover of C in copepods and polychaetes, and by measuring copepod physiological rates. Copepods feeding on Dino had the highest investment in somatic and reproductive growth. Copepods feeding on Diata had the highest N excretion rates. Egestion was a major pathway for eliminating excess C, and low food quality affected respiration rates and the intensity and speed with which dissolved organic carbon leaked from faecal pellets. Copepod physiological rates indicated that dinoflagellates are a food source of superior or similar quality to diatoms under nutrient-replete or N-depleted conditions, respectively. In addition, copepods feeding on Diata showed the highest lipid C assimilation and turnover rates. These results suggest a shift in copepod resource allocation (reproductive output or lipid accumulation) depending on food quality. Experiments with the polychaete revealed that larvae are able to regulate their lipid C content (homeostasis) regardless of the availability of dietary FA via selective accumulation and biosynthesis of FA. Lipid C assimilation results from both species, together with literature data, were used to formulate a hypothesis on different patterns of lipid homeostasis in zooplankton. These results present a robust contribution towards a better understanding of how zooplanktonic organisms might be affected by changes in the quality of their prey in the near future

Descrição comparativa dos bicos de paralarvas de Argonauta nodosa LIGHTFOOT, 1786 e Octopus vulgaris CUVIER, 1797 (Cephalopoda: Incirrata): evidências de adaptações ambientais

Orientador: Erica Alves Gonzales VidalTexto digitadoMonografia (Graduação) - Universidade Federal do Paraná, Centro de Estudos do Mar, Curso de Graduação em OceanografiaResumo: Estudos sobre as estruturas bucais e suas funções em paralarvas de cefalópodes são inexistentes na literatura e fundamentais para uma maior compreensão da ecologia e biologia destes animais. O objetivo deste estudo é examinar a morfologia e morfometria do bico de paralarvas de Argonauta nodosa e Octopus vulgaris e assim comparar as características das estruturas destes com as possíveis adaptações ambientais das espécies. Foram examinados os bicos de 32 paralarvas de A. nodosa com comprimento do manto (CM) entre 0,96mm e 8,16mm, obtidas em arrastos de plâncton na costa sul e sudeste do Brasil, com rede Bongo de 60cm de diâmetro e 300µm de malha, entre 1984 e 1997. Foram examinadas os bicos de 32 paralarvas de O. vulgaris entre 1,68 e 3,40mm de CM obtidas de um cultivo realizado no Instituto Espanhol de Oceanografia em Vigo, Espanha. Imagens digitais foram obtidas para posterior medição das estruturas das mandíbulas superior (capuz, rostro, amplitude da mandíbula, abertura da parede lateral, comprimento e largura) e inferior (capuz, rostro, amplitude da mandíbula, abertura da asa, comprimento e largura da asa e comprimento da crista e da base). Os valores foram comparados contra o comprimento do manto (CM) da paralarva através de regressão linear para determinar o crescimento relativo das estruturas e comparados entre si através de teste t para avaliar possíveis diferenças entre as espécies. Entre 20 e 32 dentes foram contados nas mandíbulas de A. nodosa e entre 20 e 34 nas de O. vulgaris, sendo que as espécies não apresentaram padrão claro de dentição. A pigmentação das mandíbulas aumenta em intensidade e área de ocorrência à medida que as paralarvas se desenvolvem, e esse processo é mais rápido e intenso em A. nodosa. Na mandíbula inferior das duas espécies é possível notar a presença de uma fenda, que sugere o não colabamento do rostro. O aspecto geral das mandíbulas variou bastante entre as espécies: o CM foi semelhante, entretanto, quase todas as estruturas medidas em A. nodosa apresentaram médias maiores que as de O. vulgaris. Este é o primeiro relato na literatura sobre dentes na mandíbula superior de paralarvas de A. nodosa. As mandíbulas de paralarvas, apesar de exibirem partes típicas do bico de um adulto, apresentam formato diferente. O capuz e as paredes laterais na mandíbula superior e o capuz e as asas na mandíbula inferior são as estruturas mais robustas do bico e possuem função importante na alimentação, uma vez que seu rápido crescimento permite adequação à ingestão de fragmentos de alimento maiores à medida que o animal cresce. Durante o desenvolvimento as mandíbulas se tornam mais robustas e aptas para a predação em ambientes competitivos, conferindo uma vantagem adaptativa aos adultos. A estrutura mandibular de A. nodosa e de O. vulgaris está relacionada à sua estratégia de alimentação e reflete tanto a evolução dos cefalópodes quanto o ambiente no qual estes estão inseridos. As paralarvas de espécies atuais conservaram características das mandíbulas de cefalópodes ancestrais. Os resultados obtidos representam informações importantes e inéditas sobre a morfologia funcional dos bicos nos primeiros estágios do ciclo de vida das espécies estudadas. Palavras-chave: Cefalópodes. Paralarva. Bico. Argonauta nodosa. Octopus vulgarisAbstract: Information on the buccal structures and their associated function in cephalopod paralarvae are unknown in the literature and fundamental to a better understanding of the ecology and biology of these animals. The aim of this study is to examine the morphology and morphometry of the beaks of Argonauta nodosa and Octopus vulgaris, and compare their characteristics with the environmental adaptations exhibited by these species. The study examined beaks from 32 paralarvae of A. nodosa with mantle length (ML) between 0,96 and 8,16mm, obtained from plankton tows between 1984 and 1997 off southern Brazil, with 60cm diameter and 300µm mesh size Bongo nets. The study also examined beaks from 32 paralarvae of O. vulgaris with ML between 1,68 and 3,40mm, obtained from a rearing experiment at the Spanish Institute of Oceanography in Vigo, Spain. Digital images were taken for later measurement of the structures of the upper (hood, rostrum, jaw amplitude, lateral walls’ opening, length and width) and lower (hood, rostrum, jaw amplitude, wing opening, wing length and width and crest and base length) jaws. The structures of the beaks were compared against the mantle length (ML) of paralarvae through linear regression, so as to determine the relative growth of the structures. Also, the structures were compared against each other through T- tests, in order to identify differences between A. nodosa e O. vulgaris. Between 20 and 32 teeth were counted on A. nodosa’s jaws, and between 20 and 34 on O. vulgaris, and neither showed a clear dentition pattern. This is the first report on the presence of teeth in the upper jaw of A. nodosa paralarvae. Jaw pigmentation becomes more intense and spread out as paralarvae develop, and this process is faster and more conspicuous in A. nodosa. In both species the lower jaws showed a tiny opening, suggesting a division in the rostrum, as if it was not completely fused by the chitin layers at the time, an ancestral characteristic of cephalopods’ jaws. The general aspect of the jaws varied considerably between the species. Almost all measured structures from A. nodosa showed higher mean values when compared to O. vulgaris of similar ML. Although the jaws of paralarvae exhibit typical parts of an adult’s beak, their format is distinct from that of the latter. The hood and lateral walls in the upper jaw and the hood and wings in the lower jaw are the most robust structures within the beak, and play a key role in feeding. Due to their rapid growth they allow the ingestion of greater food particles as the animal grows. Paralarvae of modern cephalopod species retained some characteristics of ancestral cephalopods’ jaws, but during their ontogeny the mandibles become more robust and fit for predation, an adaptive advantage to adults. The jaw structure of A. nodosa and O. vulgaris is related to the feeding strategy of each species and reflects both the cephalopod evolution throughout time and the environment in which they live. The results of this study represent important and exclusive information on the functional morphology of the beak during the first stages of the life cycle of A. nodosa and O. vulgaris. Key words: Cephalopod. Paralarvae. Beak. Argonauta nodosa. Octopus vulgari

You are not always what you eat : fatty acid bioconversion and lipid homeostasis in the larvae of the sand mason worm Lanice conchilega

The meroplanktonic larvae of benthic organisms are an important seasonal component of the zooplankton in temperate coastal waters. The larvae of the reef-building polychaete Lanice conchilega contribute up to 15% of the summer zooplankton biomass in the North Sea. Despite their importance for reef maintenance (which positively affects the benthic community), little is known about the trophic ecology of this meroplanktonic larva. Qualitative and quantitative estimates of carbon (C) transfer between trophic levels and of fatty acid (FA) specific assimilation, biosynthesis, and bioconversion can be obtained by compound-specific stable isotope analysis of FA. The present work tested the hypothesis that the concept of fatty acid trophic markers (FATM), widely used for studies on holoplankton with intermediate to high lipid contents, is also applicable to lipid-poor organisms such as meroplanktonic larvae. The incorporation of isotopically-enriched dietary C by L. conchilega larvae was traced, and lipid assimilation did not follow FA-specific relative availabilities in the diet. Furthermore, FAs that were unavailable in the diet, such as 22:5(n-3), were recorded in L. conchilega, suggesting their bioconversion by the larvae. The results indicate that L. conchilega larvae preferentially assimilate certain FAs and regulate their FA composition (lipid homeostasis) independently of that of their diet. Their quasi-homeostatic response to dietary FA availability could imply that the concept of FATM has limited application in lipid-poor organisms such as L. conchilega larvae

A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality

The Pierre Auger Observatory is the most sensitive detector to primary photons with energies above ∼0.2 EeV. It measures extensive air showers using a hybrid technique that combines a fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures of a photon-induced air shower are a larger atmospheric depth at the shower maximum (X$_{max}$) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced background. Using observables measured by the FD and SD, three photon searches in different energy bands are performed. In particular, between threshold energies of 1-10 EeV, a new analysis technique has been developed by combining the FD-based measurement of X$_{max}$ with the SD signal through a parameter related to its muon content, derived from the universality of the air showers. This technique has led to a better photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a tighter upper limit than before. The outcome of this new analysis is presented here, along with previous results in the energy ranges below 1 EeV and above 10 EeV. From the data collected by the Pierre Auger Observatory in about 15 years of operation, the most stringent constraints on the fraction of photons in the cosmic flux are set over almost three decades in energy

Study on multi-ELVES in the Pierre Auger Observatory

Since 2013, the four sites of the Fluorescence Detector (FD) of the Pierre Auger Observatory record ELVES with a dedicated trigger. These UV light emissions are correlated to distant lightning strikes. The length of recorded traces has been increased from 100 μs (2013), to 300 μs (2014-16), to 900 μs (2017-present), to progressively extend the observation of the light emission towards the vertical of the causative lightning and beyond. A large fraction of the observed events shows double ELVES within the time window, and, in some cases, even more complex structures are observed. The nature of the multi-ELVES is not completely understood but may be related to the different types of lightning in which they are originated. For example, it is known that Narrow Bipolar Events can produce double ELVES, and Energetic In-cloud Pulses, occurring between the main negative and upper positive charge layer of clouds, can induce double and even quadruple ELVES in the ionosphere. This report shows the seasonal and daily dependence of the time gap, amplitude ratio, and correlation between the pulse widths of the peaks in a sample of 1000+ multi-ELVES events recorded during the period 2014-20. The events have been compared with data from other satellite and ground-based sensing devices to study the correlation of their properties with lightning observables such as altitude and polarity