光周期对松江鲈鱼生长和性腺发育影响的初步研究

在松江鲈鱼(Trachidermis fasciatus)生长和性腺发育的关键时期,挑选其同规格的幼苗分为长光照组(LL)与自然光照组(对照组,NL),研究光周期对其生长和性腺发育的影响。本研究将LL组与NL组分别设计3组平行,共计150尾。实验起始:LL组体质量:(3.7256±0.8236)g,全长:(6.2253±0.3687)cm;NL组体质量:(3.7179±0.7893)g,全长:(6.2053±0.3436)cm,组间体质量及全长差异不显著。经过76 d的光周期实验,在前中期体质量检测中,LL组体质量、全长大于NL组;最终LL组体质量:(29.0328±3.06437)g,全长:(13.2361±0.3861)cm;NL组体质量:(28.6639±2.4460)g,全长:(13.2684±0.6432)cm;LL组的肝指数均值为(9.1525±0.5053)%,相对于NL组的(5.2675±0.1504)%,为极显著(P0.001)。最终,LL组的性腺发育指数均值为(5.8150±0.1396)%,相对于NL组的(5.7625±0.3404)%,为极显著(p0.001)。LL组肝指数(HSI)、性腺发育指数(GSI)均显著高于NL组;卵巢从外观及卵径判断,LL组已发育至第V期,大部分卵粒饱满,卵粒清亮饱满相互黏连,而NL组卵巢为第IV期,颜色偏红且卵径显著偏小。LL组卵径均值为(1.2118±0.3136)mm,而NL组则为(0.8356±0.0935)mm,LL组卵径偏大(P0.001)。结果表明:在松江鲈鱼的幼鱼至成鱼阶段,即生殖洄游阶段,适当的延长光照对松江鲈鱼的性腺发育及肝脏能量储均存有显著性影响。     

紧密角管藻的有性生殖研究

１９９４年７月在厦门近岸分离紧密度管藻，培养研究有性生殖过程和氮营养、光条件对生殖的影响。结果显示，该藻卵配生殖中，复大孢子形成后，在经里面形成一个休眠孢子，然后休眠孢子再发育成大型的原初细胞。氮营养丰富时，只有小型细胞能够性化，并且只产生雄配子，氮营养贫乏可以诱导中型细胞同时产生雌雄配子。每天１２ｈ光照和１１μＥｉｎ（ｓ．ｍ＾２）光强度最有地性化。研究结果表明，紧密角管藻有性周期中形成休眠孢子是     

Seasonal occurrence and growth of benthic algae in the Patos Lagoon estuary, Brazil

The seasonal occurrence of 94 benthic algal species, including Cyanophyta, was observed on a monthly basis over one year in the Patos Lagoon estuary (32°S, 52°W), Brazil, and showed three patterns of algal periodicity. An aseasonal group of 46 species was present throughout the year and two groups of 24 species each occurred either during summer and fall or winter and spring. The seasonal growth of 55 green, brown and red algae was correlated with monthly variations of salinity, water temperature, daylength and light radiation energy, which were measured daily in the estuary. Summer/fall peak growth was observed in 15 algae most of which correlated significantly with high salinities alone or in combination with other factors during this period. Growth peak of 11 species in winter/spring was principally a function of low water temperatures alone or together with a reduced light regime.Both periodicity of benthic algae and their seasonal growth, as a more sensitive measure of their floristic affinity, demonstrated the presence of cool temperate and tropical elements in this flora typical for warm temperate biogeographic regions. Correlations between seasonal variation of algal growth and selected environmental parameters aided in the evaluation of causal factors for algal seasonality.