Larval and juvenile Australian smelt Retropinna semoni somatic and otolith growth parameters – implications for growth interpretation of wild fish

Abstract –  Relationships between fish length, otolith size, age and weight were assessed for a population of wild Australian smelt ( Retropinna semoni ) larvae and juveniles captured over a 4-year period to aid further interpretation of growth and condition during the early life history of the species. Nonlinear smoothed generalized additive models best described the fish–otolith size relationship during the larval and juvenile period, indicating that the proportionality between fish length and otolith size varies in relation to size. It is proposed that back-calculated predictions of fish size at a previous age or otolith size, accounting for individual variation is possible by assuming a body proportional hypothesis. Growth rate of larval and juvenile Australian smelt was best described using the Gompertz model that indicated a steady decline in growth rate after around 30 days of age. The allometric growth of larval and juvenile Australian smelt established from the length/weight relationship can subsequently be used to assess the condition of fish within this population using a relative condition or relative weight condition index. The results of the study have provided significant information to enable more precise growth reconstruction and condition assessment for the species in Australian lowland rivers.     

一种新型公路划线车的专用喷涂系统

简要介绍了一种新型公路划线车专用喷涂系统的设计特点和使用功能。     

Marking springtails (Folsomia candida) with rubidium

Marking springtails is a basic tool to evaluate their fundamental ecological phenomena. Rb marking is based on the fact that enriched rubidium in an organism can be tracked trough the experiment. Our goal was to improve the rubidium-marking technique in Folsomia candida (Willem) for both microcosm and field experiments. We investigated four methodological problems of this technique, in particular, we determined the required Rb concentration in the diet to reach marking level, measured the period when labeling could be detected under two different feeding conditions, and we estimated the effects of Rb on springtails' growth. Because marked and unmarked animals are always mixed in the course of recapture we also measured the levels of contamination between labeled springtails and those in the control groups. For introducing rubidium, we fed animals with Rb-treated Baker's yeast. Rubidium-chloride labeling persisted in springtails for 27 days during which the Rb-levels in marked animals remained distinguishable from those in unmarked ones. Rb-elimination rate depended highly on the feeding conditions, with Rb-elimination being faster when food was in excess. The fitted exponential model to Rb-elimination suggested that Rb-labeling may be used for 46 and 103 days for experiments with and without food respectively. We found no effect on Collembola growth at low Rb-levels (1.2 μg Rb/g dry yeast) but at higher concentration growth was reduced. We found that contamination occurred when springtails were stored together in glycerin, however the unmarked sample with the highest Rb content was still just 4.8% of the lowest marked sample. These results provide a basis for mark-release-recapture and other studies using Rb marking on springtails.     

鮻鱼稚鱼在沿岸碎波带的出现和滞留时间

2004年3-8月在长江口沿岸碎波带5个站位用小型拖网(1 m×4 m,网目1 mm)采集到鱼稚鱼754尾,平均密度为10.9尾/网次,以6月的出现尾数最多,5月份最少。平均密度以St.2最高(80.6尾/网次)。通过研究St.2鱼稚鱼的平均体长及生长规律,其平均体长呈逐月递增趋势,表明该鱼以沿岸碎波带作为其保育场。对205尾鱼稚鱼的耳石日生长轮的观察结果,其日轮数与体长呈对数相关,并由耳石日轮数推算出其为3-6月孵化的个体。孵化后约20~46 d的个体在沿岸碎波带水域进行短期生活。鱼稚鱼在保育场的生长规律揭示了在进行海岸工程时必须强调对生态环境和水生生物保护的重要性。     

京杭大运河苏州城区段景观标识系统设计

在研究分析京杭大运河城市滨水景观的基础上,首次提出"景观标识系统"的概念和苏州城区段景观标识系统的设计方案。首先分析并提出了景观标识系统的概念,然后结合景观标识系统的功能,以景观标识系统设计的原则、组成和设计内容为依据,从形象标识、信息标识、导向标识和管理标识的角度出发,最终完成了京杭大运河苏州城区滨水空间景观标识系统的设计。目的是通过京杭大运河景观标识系统的建立,帮助游玩者顺利地完成游览活动,并获取可信的环境信息。     

杉木种子园管理和建园无性系筛选的研究

本文综合分析了45个无性系单株产量、早期败育率、中期败育率、后期败育率、中期后期总败育率、优良粒率、发芽率、活力等指标的差异,并用单指标和多指标综合评分法,从原有一代种子园淘汰15个劣质无性系来改善种子园的产量和质量;另从中选出速生、丰产、结实量高、质量好的15个无性系,结合子代测定,作为营建二代种子园材料。为现有一代种子园经营管理和二代种子园营建提供科学依据。     

国外对鱼类耳石日轮生长的研究

鱼类耳石日轮生长的研究是国际上70年代初开展起来的新领域,它的研究为我们开辟了一条更精确研究鱼类生长、鱼类生长与环境关系的新途径. 本文概述了1980年以来国际上在耳石日轮生长研究方面的进展,比较详细地介绍了日轮的观察方法、日轮的鉴定、日轮的形成与环境的关系、日轮研究的野外应用、存在的问题和展望.     

Mass-marking of grayling, Thymallus thymallus (L.), larvae by fluorochrome tagging of otoliths

Abstract Larvae of grayling, Thymallus thymallus (L.) were immersed in tetracycline hydrochloride (TC) and alizarin red S (AL) solutions for 3–4 h at concentrations of 300 and 70 ppm, respectively. Fluorescent marks on the otoliths from the marked fish were identified using a UV-light microscope. Results obtained with AL were superior to TC in marking otoliths. Fish kept in an aquarium retained good marks for 842 days. Stocking of the Carpathian River Ochotnica with marked grayling larvae revealed good mark retention for 128 days and a survival rate of approximately 12.2%.     

Abundance estimates of perch fry (Perca fluviatilis), complicated by grouped behaviour

Schnabel's mark and recapture abundance estimates of perch fry in Kli?ava Reservoir (Czech Republic), differentially marked in autumn and in spring, partly failed due to the existence of groups of individuals which behaved differently. There were three groupings. 1) a group of fry caught by shore seining from autumn of the first year (O+) to summer of the second year of life (1+), the only group in the littoral during late autumn and early spring and the fry with the slowest growth rate; 2) a group of perch fry that consisted of males maturing at 1 year and that dominated the trap catches in reservoir; 3) a group of fry that avoided the littoral in late autumn and during March-May 1983, which appeared in the littoral in May and June 1983, thus diluting the previously marked littoral fry. These 3 groupings of fry were relatively stable and separable throughout 1–2 years, apart for the mixing of groups 1 and 3 that took place in the littoral during the summer. The density of perch fry of 1982 year class in spring 1983 was estimated to be about 0.094 individuals per m².