Infaunal benthic communities of the New Zealand continental shelf

Seventeen infaunal benthic communities are recognised from sampling on the New Zealand continental shelf and upper continental slope. These are characterised in terms of geographic distribution, substrate and bathymetric range, and commoner infaunal bivalves and echinoderms.     

Age and Growth of <Emphasis Type="Italic">Sillago aeolus</Emphasis> in Okinawa Island,Japan

In a study of the age and growth of Sillago aeolus, a total of 414 fish were collected from December 2000 to March 2002, around Okinawa Island. Ages of 403 specimens were determined by otoliths. Monthly changes in the percentage of otoliths with an opaque zone in the outer margin indicated that an opaque ring formed once a year, occurring between February and May. The rings can therefore be defined as annual rings. Ages of females were estimated to be 0+ to 4+, while those of males were 0+ to 2+. The von Bertalanffy growth curves were well fitted to age-standard length data of males and females, as follows: Male: L_t = 209.6 [1 − exp{−0.70 (t + 0.58)}]. Female: L_t = 297.7 [1 − exp{−0.42 (t + 0.61)}].     

Classification of juvenile flatfishes to estuarine and coastal habitats based on the elemental composition of otoliths

The elemental composition of otoliths from juvenile English sole Pleuronectes vetulus and speckled sanddab Citharichthys stigmaeus living in estuaries and sandy coastal habitats were compared to determine if a chemical habitat tag existed that could be used to differentiate fish living in the alternative juvenile habitats. Juveniles of both species were collected from seven estuaries and 11 coastal sites along 500 km of the central California coast. Collections occurred in three years: 1998, 1999 and 2000. The chemical composition of the otoliths was analyzed using solution-based inductively coupled plasma mass spectrometry. The multi-elemental composition (Sr, Li, Ba, Mn) of otoliths from estuarine and coastal fish differed significantly for all models (global, region and years models) examined in this study. For each species, discriminant function analysis (DFA) for the global model, which pooled juveniles collected from three regions over multiple years, classified fish into estuarine and coastal groups with close to 80% accuracy. The two main elements in the discriminant models, Sr and Li, differed consistently between habitats; Sr was higher and Li was lower in estuarine fish. Classification success was modestly improved by generating separate discriminant functions for each region (regions model) because of some regional differences in Sr and Li concentrations. Classification success also was improved in some cases by generating separate discriminant functions for each year (years model) because Ba and Mn differed between habitats in only some years. Despite this variability in the concentration of elements in some regions and years, a chemical habitat tag was present in each species that could be used to discriminate coastal and estuarine juveniles over a large geographic area and over three years with very different oceanographic conditions (e.g., El Niño, La Niña). In addition, I found that English sole and speckled sanddab had striking similarities in their chemical habitat tags and that, in some cases, one species could be used as a proxy to classify juveniles of the other species without compromising the accuracy of the habitat tag. The ability to use a proxy classification model would significantly reduce the number of juvenile fish that would need to be collected and analyzed in order to classify members of an ecologically similar species. The chemical habitat tags found in this study appears to be promising tools for identifying fish that have lived in alternative juvenile habitats and, ultimately, the proportional contribution of estuarine and coastal habitats to the central California populations of English sole and speckled sanddab.     

Late Miocene fish otoliths from the Colombacci Formation (Northern Apennines,Italy): implications for the Messinian ‘Lago‐mare’ event

A fish otolith assemblage from the Messinian ‘Lago‐mare’ deposits of the Colombacci Formation cropping out in the Montecalvo in Foglia Syncline, Marche, central Italy, is described. The assemblage displays a low diversity and consists of seven taxa belonging to three families: the Gobiidae, Myctophidae and Sciaenidae. Sciaenid otoliths are the most abundant elements representing 88% of the entire assemblage. The palaeoecological analysis reveals a coastal shallow marine environment strongly influenced by continental outflow. The low diversity and high abundance of the euryecious sciaenids are indicative of a very simplified food web, which probably represented an ecological response to the fluctuating environmental parameters and available food resources. The fish remains documented here provide an unambiguous evidence that normal marine conditions were present in the Mediterranean, at least in the upper part of the ‘Lago‐mare’ event, and unquestionably demonstrate that the marine refilling preceded the Mio‐Pliocene boundary. These findings clearly demonstrate that fishes, because of their mobility and migratory behaviour, represent a useful tool for the large‐scale interpretation of the environmental conditions of the Messinian Mediterranean water body. The necessity of a new scenario of palaeoenvironmental evolution for the post‐evaporitic Messinian of the Mediterranean is also discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Insights into the diet of a poorly known species: pygmy killer whale Feresa attenuata from Cape Verde,West Africa

Despite having a worldwide distribution in tropical waters, knowledge on pygmy killer whales Feresa attenuata, including diet, is poor, with only a few studies carried out to date. The presence of otoliths and beaks in stomachs that have been examined indicate that the diet of F. attenuata includes squid, octopus and fish. In this study, the stomach contents of two F. attenuata recently stranded in Cape Verde, West Africa, were examined. A variety of fish hard parts and otoliths were recovered, in addition to the upper beak from an unidentified cephalopod and the remains of some marine arthropods. Lanternfish (Myctophidae) and deepbody boarfish Antigonia capros were identified from otoliths and comprised 95.4% of prey items. Whereas the sizes of the myctophids in the two whale stomachs were similar, those of other prey items differed. The findings provide important information on the diet of F. attenuata in the Cape Verde region.     

白洋淀和密云水库野生鲤鱼耳石热释光特征研究

鱼耳石的主体由生命矿物文石组成，其研究在过去二三十年中已取得了不少成果，但是将热释光技术用于鱼耳石的研究未见报道。本文对生长在河北白洋淀和北京密云水库的野生鲤鱼耳石的热释光曲线特征进行了研究，分析了两水域野生鲤鱼耳石中陷阱深度（E）值的差别。热释光测试结果显示，白洋淀10颗鲤鱼耳石样品热释光曲线的峰点温度（T）、发光强度（J）、积分强度（S）和半高宽（w）的均值大于密云水库，而且前者热释光曲线各参数值和E值的稳定程度均不如后者。分析还表明白洋淀鱼耳石在不同温度下的电子和空穴的逃逸几率（α）均大于密云水库。据调查，白洋淀各水体较密云水库水体的环境复杂，污染程度高。研究结果表明，鱼耳石的热释光曲线特征对鱼所生长的水体水质和水环境相当敏感，通过更深入研究，可能成为水质和水环境的重要标型。