Associated Data for "Fluctuating asymmetry as an indicator of estuarine fish health in Queensland, Australia"

Fluctuating asymmetry (FA), the minute, random deviations from perfect symmetry in morphological characters, is a potentially useful tool for assessing fish health in estuarine environments. FA has been widely used internationally as an indicator of fish health due to developmental instability in response to various environmental pressures, both natural and anthropogenic. In Australia, however, literature on the subject is sparse and the utility of the method is not well understood. As a rapidly developing, multi-use port, Gladstone Harbour is subject to a variety of stressors from industrial, commercial and community uses. The occurrence of FA in Gladstone Harbour (defined as a Moderately Disturbed estuarine system (MD)) was investigated in this study by assessing fish captured over five seasonal sampling events in 2019-2022. Sampling was undertaken in Gladstone Harbour, as well as at some relatively unimpacted sites in Central Queensland, classified as being of High Ecological Value (HEV) in the relevant Queensland Government Water Quality Objectives. Following the assumption that increased developmental instability, and therefore poorer health, is represented by increased FA in a population, it was hypothesized that fish from the moderately impacted Gladstone Harbour would exhibit higher FA than those from the less-impacted HEV sites. Five suitable estuarine fish species were targeted (Ellochelon vaigiensis, Mugil cephalus, Neoarius graeffei, Netuma thalassina, and Pomadasys kaakan), and a range of bilaterally symmetrical morphometric traits measured. There is some debate as to the efficacy of FA as an indicator of fish population health, and methodological problems are evident in the large body of literature. Measurement error (ME) is an important factor in FA studies that is often unacknowledged or poorly accounted for. This study compared two methods of taking FA measurements - (1) taking measurements by hand using digital calipers; and (2) taking measurements from digital photographs using image analysis software – to examine the impact of method on ME. It was hypothesised that image analysis software would reduce the margins for error, and that the data collected using this method would exhibit much lower levels of ME. There were no significant differences in FA between sites for all traits for all species. When analysing the data from measurements taken by hand, we found that asymmetry exceeded ME significantly in two or more traits for all species. Taking measurements using image analysis software greatly increased the chances of discovering asymmetry that exceeded ME. Almost all ME indices were decreased using image analysis software, and the results of FA analyses changed, sometimes considerably, when using image analysis software to take and record measurements. However, there were still no significant differences in FA between Gladstone Harbour and the reference sites. While the two different methods of measurement yielded datasets that were strongly correlated, correlation coefficients varied among traits within each species group. Although there are no baseline levels of FA to compare the results of this study to, it could be inferred that the FA occurring in the fish in Central Queensland estuaries, both Moderately Disturbed and HEV, is the result of natural variation, or that the differences between the condition of the study sites are not sufficient to impact fish development. While FA is an interesting potential epigenetic measure of stress, it does not appear to respond to low-level differences in estuary condition and may be better suited to monitoring the effects of specific toxicants or of highly polluted waters. This dataset contains replicate photographs of eyes, pectoral fins, pelvic fins, and otoliths of the abovementioned species of fish, as well as Microsoft Excel raw data files, cleaned data files, and manipulated SPSS and PRIMER-e data files.

波动不对称性（Fluctuating asymmetry, FA）指形态性状偏离完美对称的微小随机偏差，是评估河口环境鱼类健康状况的潜在有效工具。FA已在国际范围内被广泛用作鱼类健康的指示指标，因其可反映生物对各类自然及人为环境压力产生的发育不稳定状态。但在澳大利亚，相关主题的文献较为匮乏，该方法的应用价值尚未得到充分认知。作为快速发展的多功能港口，格拉德斯通港面临来自工业、商业及社区活动带来的多种环境压力源。本研究针对格拉德斯通港（定义为中度扰动河口系统（Moderately Disturbed estuarine system, MD））的FA发生情况展开调查，通过对2019-2022年间5次季节性采样捕获的鱼类进行分析。采样覆盖格拉德斯通港，以及昆士兰州中部若干受干扰程度较低、被昆士兰州政府《水质目标》归类为高生态价值（High Ecological Value, HEV）的区域。基于“种群发育不稳定程度越高、健康状况越差，其FA水平也越高”的前提，本研究提出假说：受中度扰动的格拉德斯通港的鱼类，其FA水平将高于受干扰程度更低的HEV区域鱼类。本研究选定5种适宜的河口鱼类物种（Ellochelon vaigiensis、Mugil cephalus、Neoarius graeffei、Netuma thalassina及Pomadasys kaakan），并测量了一系列双侧对称的形态性状。
关于FA作为鱼类种群健康指示指标的有效性尚存争议，大量相关文献中也存在方法学上的问题。测量误差（Measurement Error, ME）是FA研究中的重要影响因素，但该因素常被忽视或未得到合理处理。本研究对比了两种FA测量方法：① 使用数显卡尺手工测量；② 通过图像分析软件对数码照片进行测量，以探究测量方法对ME的影响。研究假说为：图像分析软件可降低误差范围，采用该方法收集的数据将呈现更低水平的ME。
所有物种的所有性状在不同采样点间的FA均无显著差异。对手工测量的数据进行分析时，我们发现所有物种的2个及以上性状的不对称性显著高于ME。采用图像分析软件进行测量时，发现不对称性超过ME的概率大幅提升。几乎所有ME指标在采用图像分析软件时均有所降低，且使用该软件进行测量与记录时，FA分析的结果会发生不同程度的变化，有时变化较为显著。但格拉德斯通港与参考站点间的FA仍无显著差异。尽管两种测量方法得到的数据集相关性较强，但各物种组内不同性状的相关系数存在差异。
尽管本研究缺乏可用于对比的FA基线水平，但可推断昆士兰州中部河口（包括中度扰动区域与HEV区域）鱼类的FA源于自然变异，或是研究站点间的环境差异不足以影响鱼类发育。尽管FA是一种颇具潜力的表观遗传压力监测指标，但它似乎无法响应河口环境的轻度差异，或许更适用于监测特定有毒物质或高污染水体的影响。本数据集包含上述鱼类物种的眼部、胸鳍、腹鳍及耳石的重复拍摄照片，同时包含Microsoft Excel原始数据文件、清洗后的数据文件，以及经处理的SPSS与PRIMER-e数据文件。