Factors affecting accumulation of lipofuscin age pigment in arthropod neural tissue and its use as an ecological tool for age determination

This project aimed to explore factors that modulate neurolipofuscin accumulation, using two experimental arthropod species, the locust, Locusta migratoria, and the freshwater crayfish, Pacifastacus leniusculus. The pattern of age-related accumulation of neurolipofuscin in L. migratoria was found to differ from that previously reported for crustaceans, with little accumulation prior to maturity and an exponential increase with high variability thereafter. It was shown, for the first time in any crustacean, that unilateral eyestalk ablation reduces neurolipofuscin accumulation rate in the contra-lateral eyestalk of P. leniusculus. It is hypothesized that this represents either reduced lipofuscinogenesis due to neurohormonal effects on oxidative catabolism or increased lipofuscin degradation by accelerated proteolysis following CNS damage. This finding means that longitudinal measurements of lipfuscin, i.e. in the same individual, by eyestalk biopsy, cannot be used to assessa natural lipofuscin accumulation rates in individuals of unknown age. Neurolipofuscin accumulation rate in ablated signal crayfish was found to be strongly inversely correlated with physiological age, with old individuals generally losing lipofuscin after ablation. Although this pattern is likely to be an artefact of ablation, it is the first quantitative evidence of in vivo reversibility of lipofuscin accumulation for any species and has important gerontological implications. Annual cohorts were detected by modal analysis of a neurolipofuscin concentration histogram for a pond population of P. leniusculus for the first time. Growth curves fitted to the length-at-age data obtained from this analysis were compared with results of three conventional methods for growth curve estimation: size-frequency analysis, anniversary tag-recapture and laboratory rearing. This analysis highlighted problems with extrapolation of growth rates from laboratory rearing to the field. Neurolipofuscin methodology is the only approach that can give age-length data for older individuals in the wild population and measurements of longevity

Mortality of Kalliapseudes schubartii in Unvegetated Soft Bottoms of the Estuarine Region of the Lagoa dos Patos

Studies were carried iut on seasonal mortality by taking samples of Kalliapseudes schubartii (Crustacea: Tanaidacea) for a year in the estuarine region of the Lagoa dos Patos (southern Brazil). Results demonstrated no significant difference in seasonal mortality rates, which suggest that populations of K. schubartii was heavily preyed on year round and that an assumption of a significantly higher mortality in summer/autumn than in spring/winter might not be held in unvegetated soft bottoms of the estuarine regions of the Lagoa dos Patos.Kalliapseudes schubartii (Crustacea: Tanaidacea) é um invertebrado tubícola que habita fundos moles de regiões estuarinas e que distribui-se ao longo da costa sudeste e sul do Brasil e na costa uruguaia. Este tanaidaceo é comedor de depósitos e filtrador, e é presa de vários consumidores secundários. Taxas de mortalidade sazonal foram examinadas através de amostras feitas durante um ano num local da região estuarina da Lagoa dos Patos. Os resultados não demonstraram diferenças significativas entre as taxas de mortalidade nas diferentes estações do ano, o que sugere que populações de K. schubartii são fortemente predadas ao longo de todo o ano e que a premissa de maior mortalidade no verão/outono pode não ser correta em fundos de águas rasas não vegetados

Growth, mortality, and reproduction of Excirolana brazilienssis richardson 1912 (Isopoda, Cirolanidae) on the prainha beach, Rio de Janeiro, Brazil

With the aim of estimating the growth parameters, mortality, and reproduction of a population of Excirolana braziliensis, monthly samplings were performed in the period from June 1993 to May 1995 at Prainha Beach, Rio de Janeiro, Brazil. The average size at rst sexual maturity was estimated to be 6.9 mm(TL) with an average fecundity of 13 embryos per female. There was a signi cant linear regression between the clutch size and the length of the female. The growth analyses demonstrated that there is seasonality in growth with smaller rates coincident with lower temperatures. This paper discusses the existence of a size gradient, indicated by an increase in total length with decreasing temperatures.Com o objetivo de estimar os parâmetros de crescimento, mortalidade e reprodução de uma população de Excirolana braziliensis, amostragens mensais foram feitas no período entre Junho de 1993 e Maio de 1995 na Praia da Prainha (Rio de Janeiro, Brasil). O tamanho médio da primeira maturação sexual foi estimado em 6,9 mm (CT) com fecundidade média de 13 embriões por fêmea. Houve uma signi cativa regressão linear entre o tamanho da ninhada e o comprimento da fêmea. Foi observada sazonalidade no crescimento, com menores taxas coincidindo com temperaturas mais baixas. Este artigo discute a existência de um gradiente de tamanho, indicado pelo aumento do comprimento total com a diminuição da temperatura

Bilateral comparison of in situ neurolipofuscin accumulation in Callinectes sapidus caught in the wild

Age determination using quantification of in situ neurolipofuscin has been an useful and reliable tool to understand population dynamics of crustaceans. In the present investigation, in situ neurolipofuscin was quantified in the medulla terminalis of eyestalks (cluster A cell mass, MT-A), and in the olfactory lobe cell mass 10 (OLCM-10) of the supra-oesophageal ganglion of unknown age blue crabs (Callinectes sapidus) caught in the wild. No significant difference in neurolipofuscin quantity was found between right and left MT-A and between right and left OLCM-10. Comparison between MT-A and OLCM-10 resulted in a weaker correlation. Average neurolipofuscin was 0.353+0.038% vol. and 0.896+0.105% vol. in MT-A and OLCM-10, respectively. Size explained 23% of the variation of neurolipofuscin loading in OLCM-10. No significant relationship was found between size and MT-A neurolipofuscin content. It can be concluded that both structures are suitable for the quantification of neurolipofuscin, and they have the potential for age determination for C. sapidus

Natural diet of neohelice granulata (Dana, 1851) (Crustacea, Varunidae) in two salt marshes of the estuarine region of the Lagoa dos Patos Lagoon

Natural diet of Neohelice granulata in two salt marshes of Lagoa dos Patos, RS were studied. Sampling was performed seasonally and crabs were captured by hand by three persons during one hour, fixed in formaldehyde (4%) during 24 h, transferred to alcohol (70%). Each foregut was weighed and repletion level was determined. Differences between sexes in the frequencies of occurrence of items were tested by χ2test. A total of 452 guts were analyzed. Quali-quantitative analyses were calculated following the method of relative frequency occurrence and relative frequency of the points. At both sites, for both sexes and in all seasons, the main food items were sediment, Spartina sp. and plant detritus. The highest values of mean repletion index were estimated for the spring and summer. Analysing both salt marshes, in different seasons significant shifts in the natural diet of Neohelice granulata was not observed throughout the period of study

The pink-shrimp trawling bycatch in the northen coast of São Paulo, Brazil, with emphasis on crustaceans

The pink shrimp trawling fishery (Farfantepenaeus brasiliensis and F. paulensis) in the Ubatuba region acts intensely on the populations of some benthic species. The impact of fisheries on herbenthic community is unknown. Samples of herbenthic community were obtained monthly from July/1995 to August/1996. The last haul from a commercial trawler operating on the northern coast of São Paulo State and the southern coast of Rio de Janeiro State was preserved (from being discarded) and identified at the species level. 29 species of crustaceans were found, but only Hepatus pudibundus, Callinectes ornatus, Dardanus insignis, Libinia spinosa, Sicyonia tipica, Portunus spinimanus, Portunus spinicarpus, and Persephona mediterranea had high occurrence and frequency values. Such species were the main crustacean itens in the bycatch of the pink shrimp fisheries in Ubatuba for the period of study. The total bycatch was about 1502 tons, composed by 119 tons of incidental catch and 1383 tons of discarded catch. Considering the study area, these values were quite high demonstrating that some species may have beenove rfished

The pink-shrimp trawling bycatch in the northern coast of São Paulo, Brazil, with emphasis on crustaceans

The pink shrimp trawling fishery (Farfantepenaeus brasiliensis and F. paulensis) in the Ubatuba region acts intensely on the populations of some benthic species. The impact of fisheries on herbenthic community is unknown. Samples of herbenthic community were obtained monthly from July/1995 to August/1996. The last haul from a commercial trawler operating on the northern coast of São Paulo State and the southern coast of Rio de Janeiro State was preserved (from being discarded) and identified at the species level. 29 species of crustaceans were found, but only Hepatus pudibundus, Callinectes ornatus, Dardanus insignis, Libinia spinosa, Sicyonia tipica, Portunus spinimanus, Portunus spinicarpus, and Persephona mediterranea had high occurrence and frequency values. Such species were the main crustacean itens in the bycatch of the pink shrimp fisheries in Ubatuba for the period of study. The total bycatch was about 1502 tons, composed by 119 tons of incidental catch and 1383 tons of discarded catch. Considering the study area, these values were quite high demonstrating that some species may have been overfishe

Effects of seasonality and moult cycle on the proliferation of nerve cells and on the labelling of ecdysone receptors in an estuarine crab

Decapod crustaceans show proliferation of the nerve cells in the olfactory lobe throughout their lives. However, the regulation of this process is still poorly understood, since it may vary with endogenous and exogenous factors. The objective of the present investigation was to quantify the proliferation of nerve cells and number of nerve cells with ecdysone receptors in the clusters of the central olfactory system in Neohelice granulata, according to moult stages and in different seasons (summer and winter). Three injections of bromodeoxyuridine (BrdU) were administered to the crabs. Brains were sectioned by microtome and fixed on slides for immunohistochemistry with anti-BrdU and anti-EcR antibodies. The proliferation of nerve cells was higher in winter than in summer, probably because in winter the crabs do not breed and the premoult and postmoult periods are longer. Crabs in postmoult exhibited more BrdU-labelled cells than crabs in premoult or intermoult in winter, because of a greater number of mitoses related to an increase in body size and addition of olfactory receptor neurons. The number of EcRlabelled cells was higher in premoult than in postmoult or intermoult in winter. The proliferation of nerve cells is regulated seasonally and according to moult stages