Dynamic regulation of larval fish self‐recruitment in a marine protected area

The factors that regulate the self‐recruitment of fish larvae were explored in Cabrera National Park (CNP), an insular Marine Protected Area (MPA) located off southern Mallorca (Western Mediterranean). Our study attributes the regulation of larval arrival to the MPA to a combination of retention by topographically generated circulation patterns around the island and shelf break frontal dynamics. Specifically, within the shelf, interaction of the wind‐induced oscillatory flow with the island was shown to generate ephemeral recirculation patterns that, over time, favor larval retention in the proximity of the MPA. According to our measurements, oscillatory flows produced by wind‐forced island‐trapped waves (ITWs) dominate the flow around CNP. ITW‐forced dispersion simulations were in agreement with the observed distributions of several typical fish species that breed in the CNP. A second regulator of environmental variability is the influence of boundary currents and open ocean mesoscale structures at the shelf break. These structures generate frontal zones that are comparatively more long‐lived than inner‐shelf circulation patterns, and they were shown to act as barriers to the offshore dispersion of coastal fish larval assemblages. Finally, inferences from larval size distributions around the MPA together with particle‐tracking model simulations suggested the relevance of behavioral processes for larval recruitment to the MPA. Based on these observations, the waters around the CNP can be viewed as a relatively stable system that allows breeding fish populations to rely on self‐recruitment for their long‐term persistence, independent of other source populations along the coast of Mallorca.     

Decapsulated Artemia cysts of different quality (high or low hatch‐rate) as direct food for tench (Tinca tinca L.) larvae

Three 30‐day experiments were conducted to evaluate decapsulated Artemia cysts with different quality (high or low hatch‐rate) as food for tench (Tinca tinca L.) larvae from the onset of exogenous feeding. In experiment 1, three diets were tested: Artemia nauplii‐only or cysts‐only for 30 days, and nauplii for the first 7 days and cysts thereafter. The cysts used had 86% hatching rate (high hatch‐rate cysts). The same feeding treatments were replicated in experiment 2 but with low hatch‐rate cysts (10% hatching rate). In experiment 3, five diets were tested: high hatch‐rate cysts only or low hatch‐rate cysts only for 30 days, and nauplii for the first 7, 4 or 2 days and low hatch‐rate cysts thereafter. In overall, survival was high, except with the low hatch‐rate cysts only diet. Feeding tench larvae with cysts resulted in higher growth and lower FCR compared to feeding with live nauplii only. High hatch‐rate Artemia cysts are a suitable food from the onset of exogenous feeding and low hatch‐rate cysts can be successfully used after 2–7 days feeding on nauplii.     

Allometric growth patterns and development in larvae and juveniles of thick‐lipped grey mullet Chelon labrosus reared in mesocosm conditions

Allometric growth and ontogeny were studied in thick‐lipped grey mullet Chelon labrosus reared in mesocosms from 1 to 71 day post hatching (dph). Multivariate allometric analysis of morphometric growth distinguished three distinct developmental stanzas separated by two morphometric metamorphosis lengths (L_m1 = 4.46 ± 0.06 mm; L_m2 = 28.56 ± 1.04 mm). Body mass growth also showed three distinct episodes separated by two inflections, correlated with morpho‐functional changes. First episode concerned pre‐flexion larvae and ended around 4.5 mm‐L_T (14‐dph), coinciding with estimated L_m1. It was distinguished by reduced growth, but intense morphogenesis and differentiation processes. Organogenesis and allometric changes indicated that development priorities concerned feeding efficiency, by improving detection ability (sensory system development), ingestion capacity (head growth) and assimilation performance (digestive system differentiation), together with respiration efficiency (gill development). Second episode concerned post‐flexion larvae and, ended around 8.6 mm‐L_T (25‐dph). It was distinguished by fast growth of trunk and tail, acquisition of adult axial muscle distribution and completion of gill filament development, improving locomotion and oxygenation performances. It corresponded to transition towards metamorphosing stage as indicated by later isometric growth, musculature maturation and acquisition of juvenile phenotype. Metamorphosis seemed to end at L_m2, suggesting to avoid zootechnic handling before this size.     

紫海胆不同家系早期发育、变态、生长和肠道微生物的比较

为比较紫海胆不同家系间幼体生长发育的差异,实验构建了9个紫海胆全同胞家系,比较了其受精率、孵化率、幼体存活率、变态率、开口率、幼胆生长、性腺发育和消化道微生物组成。方差分析表明,各个家系的受精率均在95%以上,无显著性差异,而其他指标在不同家系间均存在显著性差异。孵化率、早期幼体存活率、晚期幼体存活率、变态率和开口率最高的家系分别为3号(58%)、1号(83%)、4号(90%)、2号(75%)和9号(100%),最低的家系分别为6号(0%)、3号(42%)、2号(76%)、9号(6%)和5号(24.5%)。幼胆生长速率最快是3号家系为146%;最慢的是5号家系为76%。3号家系在实验结束时性腺发育明显;而其他家系性腺未见发育。3号家系的消化道微生物中拟杆菌门丰度较高,变形菌门丰度低;生长速率较慢的5号家系则与之相反。研究结果表明,紫海胆不同家系间的生产性状存在差异,具有选育改良的潜力,实验为紫海胆良种培育积累了相关数据。     

幼虫液体人工饲料中主成分对橘小实蝇的影响

研究了橘小实蝇幼虫液体人工饲料主要组成成分——啤酒废酵母和蔗糖对橘小实蝇生长发育的影响。结果表明,在一定浓度范围内,随着啤酒废酵母浓度的提高,橘小实蝇化蛹率、蛹重、羽化率、单雌产卵量、F1卵孵化率均升高,然而,当啤酒废酵母浓度高于0.142 4 g.mL-1时,化蛹率、单雌产卵量、F1卵孵化率下降;当啤酒废酵母浓度高于0.178 9 g.mL-1时,羽化率下降;当啤酒废酵母浓度高于0.215 4 g.mL-1时,蛹重下降。在一定的浓度范围内,随着蔗糖浓度的提高,橘小实蝇化蛹率、蛹重、羽化率、单雌产卵量、F1卵孵化率均升高,而当蔗糖浓度超过0.123 0 g.mL-1时,化蛹率、蛹重、羽化率下降;当蔗糖浓度超过0.152 0 g.mL-1时,单雌产卵量、F1卵孵化率下降。     

Synthetic Analogue of Butenolide as an Antifouling Agent

Butenolide derivatives have the potential to be effective and environmentally friendly antifouling agents. In the present study, a butenolide derivative was structurally modified into Boc-butenolide to increase its melting point and remove its foul smell. The structurally modified Boc-butenolide demonstrated similar antifouling capabilities to butenolide in larval settlement bioassays but with significantly lower toxicity at high concentrations. Release-rate measurements demonstrated that the antifouling compound Boc-butenolide could be released from polycaprolactone-polyurethane (PCL-PU)-based coatings to inhibit the attachment of foulers. The coating matrix was easily degraded in the marine environment. The performance of the Boc-butenolide antifouling coatings was further examined through a marine field test. The coverage of biofouler on the Boc-butenolide coatings was low after 2 months, indicating the antifouling potential of Boc-butenolide.     

黑水虻虫卵冷藏保存技术研究

【目的】持续低温或阴雨天气对黑水虻成虫产卵量造成较大影响,在产卵高峰期冷藏多余虫卵用于卵量低谷期,将有利于规模化标准化生产黑水虻。【方法】研究了不同发育阶段黑水虻虫卵经12 ℃冷藏不同天数后的孵化情况,以及原肠期虫卵经12 ℃分别冷藏5、10、15 d后在32 ℃下孵化生长发育情况。【结果】初产虫卵不能直接冷藏,12 ℃冷藏1 d后转32℃孵化,死亡率达100%。胚盘胚带形成期、原肠期、体壁背合期和破壳期的虫卵在12 ℃下冷藏10 d转置32 ℃孵化,平均孵化率分别为94%、94%、27%、0%,体壁背合期和破壳期虫卵不适宜冷藏。胚盘胚带形成期虫卵冷藏13 d后孵化率降至80%以下;原肠期虫卵冷藏15 d后孵化率降至80%以下。冷藏5、10 d原肠期虫卵孵化的幼虫生长发育与对照无显著差异;冷藏15 d原肠期虫卵存活率低于对照,百头虫重无显著差异。【结论】在12 ℃冷藏的原肠期虫卵能保持较高的存活率,幼虫生长发育正常,该结果为黑水虻的工厂化生产提供理论依据与实践指导。     

松墨天牛ADP核糖基化因子1基因的序列及表达特性分析

为了探讨Ras基因超家族中ADP核糖基化因子1基因(ARF1)在昆虫生长发育进程中以及在温度胁迫下的表达特性,以松墨天牛为研究对象,从已构建的cDNA文库中筛选到松墨天牛ARF1基因,命名为MaARF1(Gen Bank:KY368168),对其进行序列分析以及不同虫态和不同温度胁迫下的表达特性分析。结果显示,MaARF1基因编码区序列长为549 bp,编码182个氨基酸。预测蛋白质二级结构主要由α螺旋与β片层组成,其次是无规则卷曲和β转角。通过DNAMAN软件比对发现,MaARF1与赤拟谷盗ARF1蛋白氨基酸序列完全一致,二者同源性为100%,且存在1个十四酰基化位点(G~2)和5个保守域(G_1 box—G_5 box)。通过RT-qPCR分析表明,MaARF1的表达量与松墨天牛的完全变态发育相关,各虫态不间断表达,幼虫期在2龄幼虫(L2)、5龄幼虫(L5)中表达量较高,蛹化期间(L5—P0)表达量表现为上升趋势,并在第2天蛹(P2)中达到最大值,羽化期间(P10—A0)表达量表现为下降趋势;MaARF1在不同温度胁迫下均有表达,低温与高温都会导致表达量下调,温度越高或越低,表达量下调越显著。因此,MaARF1可能主要影响松墨天牛蛹化和羽化这2个变态发育关键点,从而影响整个变态发育历程,同时其也可能参与了松墨天牛体内依赖温度的Ca~(2+)信号途径。     

浓缩单胞藻在虾夷扇贝育苗中的应用效果

将超滤浓缩单胞藻分别以25％、50％、75％和100％的比例与鲜活饵料配合用于培育虾夷扇贝Patinopecten yessoensis幼虫,通过对虾夷扇贝苗种培育过程中幼体生长发育指标的观测和水质指标的分析,研究了浓缩单胞藻在贝类育苗中的应用效果。结果表明：100％浓缩藻组水质较稳定;培育前期,25％、50％的浓缩藻组对苗种无不利影响;中后期幼体的附着率、成活率均高于单独投喂鲜活饵料的对照组,表明在幼体的中后期可完全投喂浓缩单胞藻饵料。