Whitehead Michelle C, Vanetten Chelsey L, Zheng Yaxin, Lewbart Gregory A
Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States of America.
Department of Statistics, North Carolina State University, Raleigh, NC, United States of America.
PeerJ. 2019 Apr 4;7:e6669. doi: 10.7717/peerj.6669. eCollection 2019.
Largemouth bass () are an economically important freshwater fish species that have been investigated for both the short and long-term effects of stress, secondary to angling. Limited data has been published on the hematological parameters of this species and blood sample stability is a notable limitation of hematologic field studies. A relatively novel technique using 10% neutral buffered formalin preserves heparinized whole blood and maintains blood cell stability beyond one month in striped bass. The objective of this study was to evaluate the differences in hematological parameters between tournament-caught and captive-raised largemouth bass using whole blood preservation with neutral buffered formalin.
Two populations of largemouth bass ( = 26 wild; = 29 captive) underwent coccygeal venipuncture to collect heparinized whole blood for packed cell volume, total solids, and manual differential. Formalin preservation of heparinized whole blood facilitated manual hemocytometer analysis. Results were compared between the populations (tournament-caught, and captive-raised) with Wilcoxon rank sum test, a Hotelling's test, and Bonferroni simultaneous 95% confidence intervals to determine significance.
The mean packed cell volume (44.9 ± 5.4%) and total solids (7.2 ± 1.1 g/dL) were significantly higher, while the total leukocyte count (7.08 ± 1.86 × 10/µL) was significantly lower in the wild tournament-caught population of largemouth bass, as compared to the captive-raised counterparts (PCV 34.4 ± 7.2%; TS 5.2 ± 1.0 g/dL; WBC 16.43 ± 8.37 × 10/µL). The wild population demonstrated a significantly distinct leukogram characterized by a neutropenia (24.1 ± 12.7%), lymphocytosis (67.7 ± 13.0%), and monocytopenia (8.3 ± 2.9%), while the erythrocyte and thrombocyte counts were not significantly different between populations.
Numerous factors have been demonstrated to influence hematologic parameters in fish including age, size, sex, temperature, environmental oxygen level, population density, and infection. The wild population endured stress during angling capture, live-well hypoxia, transport, and extended air exposures at weigh in, which may have caused a stress leukopenia as well as osmoregulatory dysfunction and subsequent hemoconcentration. Further evaluation of seasonal impact as well as increased sample size is warranted to enhance our understanding of largemouth bass hematology.
This study concluded that wild largemouth bass captured via tournament angling have higher packed cell volume and total solids, and lower total leukocyte counts, compared to captive-reared individuals. Through the completion of this study, we demonstrated the successful use of 10% neutral buffered formalin to preserve heparinized whole blood for precise hemocytometer cell counts in a new teleost species, the largemouth bass.
大口黑鲈是一种具有重要经济价值的淡水鱼类，人们已经对其因垂钓产生的应激的短期和长期影响进行了研究。关于该物种血液学参数的已发表数据有限，并且血液样本稳定性是血液学野外研究的一个显著限制因素。一种使用10%中性缓冲福尔马林的相对新颖的技术可以保存肝素化全血，并使条纹鲈的血细胞稳定性维持超过一个月。本研究的目的是使用中性缓冲福尔马林保存全血来评估竞技钓获的大口黑鲈和圈养的大口黑鲈之间血液学参数的差异。
两组大口黑鲈（野生组n = 26；圈养组n = 29）接受尾静脉穿刺以收集肝素化全血，用于检测血细胞比容、总固体含量和手工分类计数。福尔马林保存肝素化全血便于进行手工血细胞计数板分析。使用Wilcoxon秩和检验、Hotelling's T²检验和Bonferroni同时95%置信区间对两组（竞技钓获组和圈养组）的结果进行比较，以确定差异是否显著。
与圈养的大口黑鲈相比（血细胞比容34.4 ± 7.2%；总固体含量5.2 ± 1.0 g/dL；白细胞计数16.43 ± 8.37×10⁹/µL），野生竞技钓获的大口黑鲈的平均血细胞比容（44.9 ± 5.4%）和总固体含量（7.2 ± 1.1 g/dL）显著更高，而白细胞总数（7.08 ± 1.86×10⁹/µL）显著更低。野生组呈现出明显不同的白细胞分类特征，表现为中性粒细胞减少（24.1 ± 12.7%）、淋巴细胞增多（67.7 ± 13.0%）和单核细胞减少（8.3 ± 2.9%），而两组之间的红细胞和血小板计数没有显著差异。
已证明许多因素会影响鱼类的血液学参数，包括年龄、大小、性别、温度、环境氧气水平、种群密度和感染。野生组在垂钓捕获、活鱼舱缺氧、运输以及称重时长时间暴露于空气中的过程中承受了应激，这可能导致了应激性白细胞减少以及渗透调节功能障碍和随后的血液浓缩。有必要进一步评估季节影响以及增加样本量，以加深我们对大口黑鲈血液学的理解。
本研究得出结论，与圈养的大口黑鲈相比，通过竞技垂钓捕获的野生大口黑鲈具有更高的血细胞比容和总固体含量，以及更低的白细胞总数。通过完成本研究，我们证明了成功使用10%中性缓冲福尔马林保存肝素化全血，以便在一种新的硬骨鱼物种大口黑鲈中进行精确的血细胞计数板细胞计数。
