The mating system of the Weddell seal, Leptonychotes weddelli

Metadata record for data from ASAC Project 2184See the link below for public details on this project.The objectives of this project were:To characterise the mating system of the Weddell seal by:1) acoustically tracking males under the ice during the breeding season,2) measuring changes in health and condition of individual males over the breeding season,3) determining whether vocalisations are used as advertisements of individual quality to attract females, and/or in male-male competition,4) develop and use a combination of microsatellite loci tests to assign paternity to newborn pups, and then use these results to determine whether the variance in male mating success is related to territory size, tenure and/or individual characteristics.A large number of collected data files are available for download. Many files are in an unknown format, but will open with a standard text editor. See below for summaries of the two seasons of fieldwork.1997/1998 Season:In November/December 1997, we conducted a pilot study at the Turtle Rock colony (77.727S, 166.85E) in McMurdo Sound. All of the techniques outlined in the proposal were successfully trialled. Acoustic pingers were attached to seven males and five females for a total deployment of 104 seal days and mass and morphometrics obtained for each animal. Preliminary analysis of male movements indicate that males held adjacent yet non-overlapping territories on the southern side of Turtle Rock, along a major ice crack and where the congregation of females was highest. Both the size and shape of the males territories, and the evidence from the vocalisation data show that we captured the dominant males at the site.Both males and females were immobilised using Ketamine/Diazepam with no loss of an animal, nor signs of respiratory depression. Vocalisations were recorded from all territory holding males, and both behavioural and vocal responses of both male and female seals to familiar and unfamiliar calls were observed. We bleach marked all animals to which we attached pingers and these markings were visible on our under-ice video - with which we also recorded behavioural responses to both animals and our under-ice speaker during playback experiments. We conducted a daily census of all animals at Turtle Rock and above-ice movements were recorded. Skin samples were taken from 24/25 males seen at the site and 43/45 mother-pup pairs (One male was only seen on a single occasion at the colony, though sighted elsewhere, and two females disappeared shortly after our arrival at the colony).Significant findingsDominant males hold under-ice territories which are adjacent yet non-overlapping - however territory boundaries change considerably over the course of the breeding season. Males respond to playbacks of their own and others calls as do females. Females towards the end of lactation will visit each males territories. Whether to assess individual males or not is yet to be determined.1998/1999 SeasonBetween October 29 through December 10 1998, the behaviour of male and female weddell seals at the Turtle Rock colony (77.727S, 166.85E) were monitored both above and below the ice. This season, we switched from the seal sled method of capture and restraint (see K027 report 1997) to the use of a pole net and tripod. Seals were bagged by placing a seal hood over their head and then a 3m pole net (consisting of two, 3m long poles connected by a 2m wide, 2.5cm mesh, net , was placed over them and the poles tied tightly at both ends, leaving them constrained within the netting bag. The pole net was then hoisted under a tripod (built by Antarctica New Zealand) using a chain block suspended from the head of the tripod, and the animal weighed using electronic scales. For attachment of instruments, animals were immobilised with an intra-muscular injection of Ketamine/Diazepam at a dose rate of approximately 2.0mg/100 kg Ketamine, 0.4mg/100 kg Diazepam as was used successfully in 1997. Animals were only immobilised for attachment of instruments with HR electrodes (ie 3 males and 7 females). Animals were not immobilised for removal of instruments with the exception of one female who was particularly active. A small number of untagged animals were tagged in the rear flippers using tags provided by the University of Minnesota Weddell seal program as part of their long-term studies of the McMurdo Sound Weddell seal population. Maximum animal handling time including gluing of instruments and allowing for equilibration of isotopes (see below) was approximately 3 hours/seal. The mass of animals at first and last capture is shown in Table 1 below.Animal Movements - Males: Movements under the ice were monitored using depth modulated acoustic transmitter (Vemco V16P). An array of three hydrophones, each approximately 500m apart, was placed around the colony on the southern side of Turtle Rock.. The position of each animal (x, y, z locations) was automatically logged when it was underwater at intervals of between 15 and 60 sec. The array was powered continuously using 12V dry-fit batteries connected in series. A VHF radio transmitter (Sirtrack) was glued to the dorsal surface of each male using a quick-dry Epoxy (Araldite). Time depth recorders (MkV1) Heart rate loggers, and an Acoustic Heart Transmitter were attached to three males. The VHF transmitter was used to assist in relocating animals that left the study site during the breeding season and to monitor time spent on the ice via a Televilt Scanning receiver mounted atop a Wannagan placed near the SW side of Turtle Rock. The position of males on the surface at the colony was also mapped approximately once every two days.Females: Under ice movements and feeding behaviour of six females was monitored by attachment of acoustic pingers as outlined above. We attached Time depth recorders (MkV1) Heart rate loggers, and an Acoustic Heart Transmitter to each of five of these females, the sixth did not appear to transmit heart-rate. A seventh female was captured but no instruments fitted, as she did not respond to the immobilising agents.Energetics -Body composition of 12 males was determined by measuring total body water using hydrogen isotope dilution on two separate occasions. At first capture, a blood sample (5ml) was drawn directly into Vacutainer collection tubes from the femoral vein at the base of the rear flippers using a 1 * inch, 18g needle and each animal was then injected with 5ml tritiated water (HTO) (specific activity 1 mCi per ml). The animal was then weighed as outlined above. Unless further instrument attachment was to occur, the animal was then released in order to allow the HTO to equilibrate with the body water pool (approximately three hours), and later recaptured for a second blood sample to be taken. Recapture and sampling usually took less than 10min. The blood samples were allowed to settle in the warmth of the Apple in the field and the serum fraction separated. Aliquots of serum were then held frozen for later analysis in Australia at the University of Tasmania. This procedure was repeated later in the season, and the changes in mass and TBW will be used to estimate energy expenditure (Reilly and Fedak 1991).Mass changes are shown in Table 1.Seal Tag Name Mass1 (kg) Mass2 (kg) Mass loss Seal Days Rate of mass lost/dayPurple 37 #1 Dudley 413.5 354.5 59 24 2.46Purple 547 #2 Shed 369.5 319.5 50 20 2.50Pink 928 #3 385.5 338.5 47 22 2.14Red CT 283/965 #4 352.5 304.5 48 22 2.18White 423 #5 King C 455 428.5 26.5 22 1.20Pink 981 #6 Whiteboy 370.5 331.5 39 17 2.29Y1339 #7 405.5 384.5 21 15 1.40Pink CT 549 #8 Joe 362 325.5 36.5 15 2.43Y1299 #9 Markboy 314.5 280.5 34 16 2.13Orange CT 842 #10 344.5 293.5 51 14 3.64Purple 808 #11 337.5 . .Red 347 #12 313.5 . .2) Function of VocalisationsMethod:Hydrophones were used to obtain several recordings of five major call types from 8 of our captured males (pinger frequency allowed us to distinguish between individuals occupying the array). Following the 1999 field season, a correlational analysis will be used to determine if information on male characteristics (assessed using our physiological measures of their health or "quality") are revealed by vocalisations of the males we sampled over the three field seasons. Our current total sample size for this component of the research stands at 13 (1997 and 1998). It has become increasingly clear that the Long Trill calls, produced exclusively by males, may play important role in attracting females and challenging rivals. Two playback experiments were conducted to examine the function(s) of this important vocalisation, and other call types used by males. In the first experiment (initiated in 1997), the responses of 8 monitored males and a single female to the playback of each major call type and a control sound (walrus calls) were examined according to a systematic experimental schedule. For both males and females, we were able to record changes in position relative to the underwater speaker (using data from the pinger array), vocal behaviour (using a DAT recorder and a pair of hydrophones), activities near the playback speaker (using three underwater video cameras), swimming speed and heart rate of specific animals. Our current total sample size for this component of the research stands at 13 males and 2 females (1997 and 1998). The second experiment (also initiated in 1997) examined male-male competition and inter-sexual call function more directly. Our pilot study showed that males actively overlap the Long Trill songs of rivals with their own Trills, in a manner that is similar to territorial songbirds. We conducted "interactive" playback experiments to examine the consequences of overlapping the Long Trill calls of rivals. Five consecutive Long Trill calls of specific resident males (identified using a "real time" field spectrograph) were either (1) completely overlapped, (2) partially overlapped or (3) preceded by the recorded Long Trill calls of an unfamiliar male. A MiniDisc player was used to broadcast these calls to different resident males according to a systematic schedule. Underwater video cameras, the pinger array and hydrophones were then used to record the changes in patterns of under-ice movements and the vocal responses of 4 males and 5 females. Our current total sample size for this component of the research now stands at 7 males and 8 females (1997 and 1998). We also obtained continuous sound and video samples of male and female Weddell seals occurring along the main ice crack at Turtle Rock using a timelapse VCR connected to fixed video cameras and a hydrophone.3) Paternity analysis: collection of samplesMethodThe mating success of males at Turtle Rock will be determined by laboratory analysis of skin samples (6 mm diameter). These were collected from the edge of the interdigital webbing of the hind flipper using a leather punch, from all males, females and pups in 1997 and 1998, with further collections planned for 1999 and 2000. Samples were stored in eppendorf tubes filled with 100% ethanol. Sample degradation is minimal using this technique. Analysis has still to be conducted. This season we trialled a new technique for sampling using a small biopsy punch on the end of a pole but this technique proved unsatisfactory as biopsy heads became blunt after only 2-3 animals had been sampled. However, the clipping technique proved so successful that an experienced clipper could remove samples with such discretion that at times the animal being sampled did not wake.Significant findingsSome of the results from the first year of this study were presented at the SCAR conference in Christchurch last August, and the abstract published in the NZ Natural Sciences series.Harcourt, R.G., Hindell, M.A. and Waas, J.R. 1998. Under-ice movements and territory use in free-ranging Weddell seals during the breeding season. New Zealand Natural Sciences 23: 72-73One of the most interesting findings relates to the interpretation of three dimensional dive profiles. One paper on three dimensional dive profiles in free-ranging Weddell seals is nearing completion. Other planned papers include measurement of heart-rate during diving, female foraging behaviour, communication and territorial behaviour, as well as the major reproduction papers.

本数据集元数据来自ASAC项目2184，项目公开详情请见下方链接。本项目的研究目标如下：
1. 通过声学手段追踪繁殖季冰下雄性威德尔海豹（Weddell seal）的活动；
2. 监测繁殖季内雄性个体的健康与身体状况变化；
3. 明确鸣声是否用于展示个体质量以吸引雌性，或用于雄性间的竞争；
4. 开发并结合微卫星位点检测技术为新生幼崽确定父权，随后利用该结果分析雄性交配成功率的差异是否与领地面积、领地持有时长及/或个体特征相关。

本项目收集了大量数据文件可供下载，多数文件格式未知，但可通过标准文本编辑器打开。以下为两次野外工作季的研究概况。

### 1997/1998野外季
1997年11-12月，我们在麦克默多湾（McMurdo Sound）的龟岩（Turtle Rock）繁殖群（77.727°S，166.85°E）开展预实验。研究方案中提出的所有技术手段均顺利完成测试。我们为7只雄性和5只雌性个体佩戴了声学信标，总有效佩戴时长为104海豹日，并为每只个体测量了体重与形态测量数据。对雄性移动模式的初步分析显示，雄性个体在龟岩南侧沿主要冰裂缝区域建立了相邻但不重叠的领地，该区域也是雌性聚集密度最高的地带。雄性领地的面积与形态，以及鸣声数据均证实，我们成功捕获了该区域的优势雄性个体。

所有雄性与雌性个体均通过氯胺酮（Ketamine）/地西泮（Diazepam）完成麻醉，无个体死亡或呼吸抑制症状。我们记录了所有领地雄性的鸣声，并观察到雌雄海豹对熟悉与陌生鸣声的行为与鸣声反应。我们为所有佩戴信标的个体进行了漂白标记，该标记可在冰下视频中清晰识别；实验期间我们还通过冰下视频记录了海豹对受试个体与冰下扬声器的行为反应。我们每日对龟岩区域的所有个体进行普查，并记录了个体在冰面的移动情况。我们采集了该区域内24/25只观测到的雄性个体，以及43/45对母幼对的皮肤样本（1只雄性仅在繁殖群出现过1次，但在其他区域被观测到；另有2只雌性在我们抵达繁殖群后不久失踪）。

#### 主要研究发现
优势雄性拥有相邻但不重叠的冰下领地，但领地边界在繁殖季内会发生显著变化。雄性与雌性均会对同类鸣声回放产生反应。处于哺乳后期的雌性会造访每一只雄性的领地，雌性是否通过该行为评估雄性个体，目前仍有待确认。

### 1998/1999野外季
1998年10月29日至12月10日，我们在龟岩繁殖群（77.727°S，166.85°E）开展了冰上与冰下的海豹行为监测。本季我们将原有的海豹雪橇式捕获约束方法（详见1997年K027报告）更换为杆式网兜与三脚架装置。捕获时，先将海豹头罩套在海豹头部，再将3米杆式网兜（由两根3米长杆连接一张2米宽、2.5厘米网眼的网组成）罩住海豹，随后将杆的两端绑紧，使海豹被约束在网兜内。随后通过由新西兰南极局（Antarctica New Zealand）搭建的三脚架顶部悬挂的链式滑车将网兜吊至冰面，并用电子秤称量海豹体重。

为佩戴仪器，我们参照1997年的成功方案，通过肌肉注射氯胺酮/地西泮对个体进行麻醉，给药剂量为每100千克体重使用2.0mg氯胺酮与0.4mg地西泮。仅在佩戴心率（HR）电极时对个体进行麻醉，共计3只雄性与7只雌性个体。除1只极度活跃的雌性个体外，其余个体拆卸仪器时均无需麻醉。我们使用明尼苏达大学威德尔海豹研究项目提供的标记物，为少量未佩戴标记的个体在后鳍肢佩戴标记，该项目长期监测麦克默多湾的威德尔海豹种群。包括粘贴仪器与同位素平衡（详见下文）在内的最长个体处理时长约为每只3小时。个体首次与末次捕获的体重数据详见下表1。

#### 个体移动模式
##### 雄性个体
冰下移动通过深度调制声学发射器（Vemco V16P）进行监测。我们在龟岩南侧的繁殖群周边布置了三台水听器阵列，各水听器间距约500米。当个体在水下时，系统会自动记录其三维位置坐标（x、y、z轴），记录间隔为15至60秒。该阵列通过串联的12V干电池持续供电。我们使用快干环氧树脂（Araldite）将甚高频（VHF）无线电发射器（Sirtrack）粘贴在每只雄性个体的背部，并为3只雄性个体佩戴了时间深度记录仪（MkV1）、心率记录仪与声学心脏发射器。VHF发射器用于辅助定位离开研究区域的个体，并通过安装在龟岩西南侧Wannagan平台上的Televilt扫描接收器监测个体在冰面的停留时长。我们约每两日对冰面繁殖群内雄性个体的位置进行一次测绘。

##### 雌性个体
我们通过上述声学信标监测了6只雌性个体的冰下移动与觅食行为。我们为其中5只雌性个体佩戴了时间深度记录仪（MkV1）、心率记录仪与声学心脏发射器，第6只个体未传输心率数据。另有1只雌性个体被捕获，但未佩戴任何仪器，因其对麻醉剂无反应。

#### 能量代谢
我们通过两次氢同位素稀释法测定总体水分（TBW, total body water），以此评估12只雄性个体的身体成分。首次捕获时，我们使用1英寸18G针头从后鳍肢基部的股静脉采集5ml血液样本至真空采血管（Vacutainer），随后为每只个体注射5ml氚化水（HTO, tritiated water），比活度为1mCi/ml。随后按照前述方法称量个体体重。若无额外仪器佩戴需求，我们会将个体释放以等待氚化水与身体水池达到平衡（约需3小时），之后再次捕获并采集第二次血液样本。再次捕获与采样的时长通常少于10分钟。血液样本在野外的Apple保温装置中静置，随后分离血清组分；血清分装后冷冻保存，后续将送往澳大利亚塔斯马尼亚大学进行分析。本季后期我们重复了该流程，体重与总体水分的变化将用于估算能量消耗（Reilly和Fedak，1991）。体重变化数据详见下表1。

| 海豹标记名称 | 初始体重(kg) | 末次体重(kg) | 体重损失量 | 有效佩戴天数 | 日均体重损失量(kg/天) |
|-------------------|-------------|-------------|-----------|-------------|---------------------|
| 紫色37号（#1 Dudley） | 413.5 | 354.5 | 59 | 24 | 2.46 |
| 紫色547号（#2 Shed） | 369.5 | 319.5 | 50 | 20 | 2.50 |
| 粉色928号（#3） | 385.5 | 338.5 | 47 | 22 | 2.14 |
| 红色CT 283/965号（#4）| 352.5 | 304.5 | 48 | 22 | 2.18 |
| 白色423号（#5 King C）| 455 | 428.5 | 26.5 | 22 | 1.20 |
| 粉色981号（#6 Whiteboy）| 370.5 | 331.5 | 39 | 17 | 2.29 |
| Y1339号（#7） | 405.5 | 384.5 | 21 | 15 | 1.40 |
| 粉色CT 549号（#8 Joe）| 362 | 325.5 | 36.5 | 15 | 2.43 |
| Y1299号（#9 Markboy）| 314.5 | 280.5 | 34 | 16 | 2.13 |
| 橙色CT 842号（#10） | 344.5 | 293.5 | 51 | 14 | 3.64 |
| 紫色808号（#11） | 337.5 | - | - | - | - |
| 红色347号（#12） | 313.5 | - | - | - | - |

### 2. 鸣声功能
#### 研究方法
我们利用水听器记录了8只捕获雄性个体的5种主要鸣声类型（信标频率可区分阵列内的不同个体）。1999野外季结束后，我们将通过相关分析明确，在三次野外季采样的雄性个体的鸣声是否传递了其生理健康或"质量"相关的特征信息。本研究该部分的当前总样本量为13只个体（1997与1998季数据）。

现有研究结果愈发表明，仅雄性个体发出的长颤音（Long Trill）可能在吸引雌性与挑战竞争对手方面发挥重要作用。我们开展了两次回放实验，以明确该重要鸣声以及雄性其他鸣声类型的功能。

首次实验始于1997年，我们按照系统实验流程，测试了8只观测雄性与1只雌性对各主要鸣声类型以及对照声音（海象鸣声）的反应。针对雌雄个体，我们可通过信标阵列记录其相对于水下扬声器的位置变化，通过数字音频磁带（DAT）记录仪与水听器记录其鸣声行为，通过三台水下摄像机记录回放扬声器附近的活动，并记录特定个体的游泳速度与心率。本研究该部分的当前总样本量为13只雄性与2只雌性个体（1997与1998季数据）。

第二次实验同样始于1997年，更直接地测试了雄性间竞争与雌雄间鸣声的功能。预实验结果显示，雄性个体会主动用自身的长颤音重叠竞争对手的长颤音，这一行为与领地鸣禽类似。我们开展了"交互式"回放实验，以测试重叠竞争对手长颤音的行为后果。我们选取特定领地雄性的连续5次长颤音（通过实时野外声谱仪识别），分别设置三种处理方式：1）完全重叠该鸣声；2）部分重叠该鸣声；3）用陌生雄性的长颤音先于该鸣声播放。我们按照系统流程，使用迷你光碟（MiniDisc）播放器向不同领地雄性播放上述处理后的鸣声。随后我们利用水下摄像机、信标阵列与水听器，记录了4只雄性与5只雌性个体的冰下移动模式变化以及鸣声反应。本研究该部分的当前总样本量为7只雄性与8只雌性个体（1997与1998季数据）。

我们还通过连接固定摄像机与水听器的延时录像机，记录了龟岩区域主要冰裂缝沿线雌雄威德尔海豹的连续声像样本。

### 3. 父权分析：样本采集
#### 研究方法
我们将通过实验室分析皮肤样本（直径6mm），确定龟岩繁殖群雄性个体的交配成功率。1997与1998季，我们使用皮革打孔器从所有雄性、雌性与幼崽的后鳍肢趾间蹼边缘采集样本，1999与2000季计划进一步采集样本。样本储存在装有100%乙醇的离心管（Eppendorf管）中，该储存方法可最大程度降低样本降解风险。相关分析仍在进行中。

本季我们测试了一种新型采样技术：使用安装在杆末端的小型活检打孔器，但该技术效果不佳，因为仅采样2-3只个体后打孔头就会变钝。但剪取技术效果极佳：经验丰富的采样人员可精准剪取样本，有时被采样的个体甚至不会苏醒。

#### 主要研究发现
本研究第一年的部分结果已于去年8月在基督城举办的SCAR（南极科学研究委员会）会议上展示，摘要发表于《新西兰自然科学》系列期刊：
> Harcourt, R.G., Hindell, M.A. and Waas, J.R. 1998. Under-ice movements and territory use in free-ranging Weddell seals during the breeding season. *New Zealand Natural Sciences* 23: 72-73

最有趣的研究发现之一与三维潜水剖面的解读相关，一篇关于自由活动威德尔海豹三维潜水剖面的论文即将完成。其他计划发表的论文内容包括潜水期间的心率测量、雌性觅食行为、交流与领地行为，以及核心繁殖相关研究。