Technical note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment

Various methods have been used to remove organisms from sediments to investigate structure and function of faunal assemblages in intertidal habitats. Nevertheless, little is known about how these treatments affect properties of the sediments themselves, although changing these properties may cause changes in the assemblages, independently of other hypotheses being tested. This study assesses the efficacy of defaunation and effect on selected biogeochemical properties of five different methods of defaunating soft muddy sediments in an estuary. The methods were removal and freezing of sediment, removal and oven-heating, freezing in situ with liquid N2, spraying with formalin and spraying with hydrogen peroxide. The first four of these methods have been used in previous studies, whilst the fifth was considered to be a potentially useful defaunator because it does not leave toxic residues. The first two methods required sediment to be brought back to the lab, disrupting the natural structure of the sediment; the last three were done in situ, with much less disturbance.  Variables measured to assess effects of the treatments on the sediment were amount of water, grain size, total carbohydrate, suspension index (relative erosion rate), erosion threshold, chlorophyll a and b, colloidal carbohydrate, Fo (minimal fluorescence) and Fv/ Fm (photosynthetic yield). There were no significant effects of any treatment on the first four variables. For the others, effects of defaunation varied from treatment to treatment and with time after treatment. Generally, the greatest disturbance was to the microphytobenthos (MPB, measured by chlorophyll and fluorescence) and related variables. For most treatments, recovery was rapid, but the effects of formalin and H2O2 persisted for a few days. Effects on physical properties of the sediment were mostly minor and insignificant. Removal and freezing or heating, however, caused major changes to the sediments because of the disturbances involved. Choosing the appropriate method of defaunation is very important if interpretations are not to be confounded between the effects of defaunation per se and any effects of changes to other biota (such as microphytobenthos) and/or the properties of sediments caused by the method used to defaunate experimental areas

Efeito do intervalo de alimentação na reprodução e na longevidade do predador Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae).

O efeito do intervalo de alimentacao em femeas de Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae), foi estudado a 24 +\\- 3oC, UR de 70 +\\- 10% e fotofase de 12 horas. Os tratamentos consistiram no fornecimento de larvas de Musca domestica L. (Diptera: Muscidae), durante 24 horas a cada um, dois, quatro, oito ou 16 dias. Femeas de P. nigrispinus, alimentadas a cada um, dois e quatro dias, produziram maior numero de ovos (225,4; 184,6 e 135,3 ovos, respectivamente), que aquelas alimentadas a cada oito ou 16 dias (8,3 e 0,0 ovos, respectivamente). A longevidade das femeas que receberam presa a cada quatro dias (43,0 dias), foi maior do que aquelas alimentadas a cada oito ou 16 dias (27,3 e 10,6 dias)

Can the study of self-assembly in solution lead to a good model for the nucleation pathway? The case of tolfenamic acid

To further our understanding of the role of solution chemistry in directing nucleation processes new experimental and computational data are presented on the solution and crystallisation chemistry of tolfenamic acid (TA), a benchmark polymorphic compound. With these, and previously published data, we were able to establish that TA is rapidly fluctuating between conformers in solution with either solvated monomers or dimers present depending on the solvent. Hence, despite the fact that conformational polymorphs can be obtained from crystallisations in ethanol, we found no links between solution chemistry and crystallisation outcomes. We discuss the implications of these conclusions for the nature of the nucleation pathway via dimers and clusters and raise experimental questions about how best to undertake relevant crystallisation studies

Preliminary attempt to develop a path-flow analysis model for swimming performance in children

The aim of this research was to develop a path-flow analysis model from age-group swimmer’s performance based on biomechanical and energetic parameters. Twenty two young male age-group swimmers with several competitive levels volunteered to serve as subjects. It was assessed swim velocity, stroke length, stroke frequency, stroke index, propulsive efficiency, critical velocity and 200 m freestyle event performance. To verify the quality of the model, root mean square residuals (RMSR) was computed. The confirmatory model explained 54% of swimming performance. RMSR was 0.064. As a conclusion, the model based in biomechanical and energetic variables, according to the relationships suggested is appropriated to explain performance in age-group swimmers

Preliminary attempt to develop a path-flow analysis model for swimming performance in children

The goal of competitive swimming is to travel the event distance as fast as possible. The identification of the parameters that predict swimming performances is one of the main aims of the swimming “science” community. Indeed, it is consensual that biomechanical and energetic variables are determinant for performance in this sport. Several research groups dedicate their attention to the relationships establish between biomechanical and energetic variables on adult swimmers, with special emphasis on elite adult swimmers

Comparação cinemática e neuromuscular de um exercício de abdominais no solo e na fitball

O objectivo deste estudo foi comparar a cinemática e a actividade neuromuscular em exercícios de abdominais no solo e na Fitball. Quinze jovens mulheres participaram voluntariamente neste estudo. Cada sujeito efectuou duas vezes, três séries de dez abdominais com um intervalo mínimo de 60 segundos entre cada série. O exercício foi efectuado uma vez no solo e outra na Fitball. Os dados cinemáticos e neuromusculares foram recolhidos ao longo de todo o protocolo. Foi avaliada a actividades neuromuscular do recto femoral, do recto abdominal superior, do recto abdominal inferior e do oblíquo externo. Um electrogoniómetro foi colocado entre a sexta costela e a crista ilíaca (coluna) e outro entre a crista ilíaca e a zona trocantérica (anca) para avaliação cinemática. O período do exercício entre as condições em estudo não foi significativo. O ângulo mínimo da anca e da coluna lombar foram significativamente inferiores durante a execução do exercício no solo do que na Fitball. A actividade neuromuscular foi significativamente superior quando o exercício foi realizado na Fitball do que no solo em todos os grupos musculares. Como conclusão, actividade neuromuscular é superior aquando da exercitação na Fitball do que no solo

Path-flow analysis model for anthropometric, hydrodynamic and biomechanical variables in age-group swimmers

The goal of competitive swimming is to travel the event distance as fast as possible. The identification of the parameters that predict swimming performances is one of the main aims of the swimming “science” community

Evolution in swimming "science" research

Swimming seems to be one of the sports more studied . More than one decade ago, Clarys (1996) made an content analysis of the research about swimming. However, in these last 13 years several developments happened in the aquatic activities

Path-flow analysis model for anthropometric, hydrodynamic and biomechanical variables in age-group swimmers

The aim of this research was to develop a path-flow analysis model for age-group swimmer’s speed based on anthropomeric, hydrodynamic and biomechanical determinants

Evolution on Swimming Science Research: content analysis of the “Biomechanics and Medicine in Swimming” Proceedings Books from 1971 to 2006

Swimming seems to be one of the sports more studied . More than one decade ago, Clarys (1996) made an content analysis of the research about swimming. However, in these last 13 years several developments happened in the aquatic activities