碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 102 / Present study analysed statolith chemical signature and microstructure to investigate monthly early life growth variation of swordtip squid (Uroteuthis edulis) off northeastern Taiwan, and to discriminate different hatching cohorts by using the statolith elemental composition of individuals at their early life stage. Samples were collected between July, 2011 and December, 2012 from northeastern Taiwan. Mantle length ranged from 7.9-279.0 mm, wet body weight ranged from 0.2-372g and the number of daily growth increments ranged 41-254 days. Radius of natal ring (NRR) and incremental widths (IW) in statolith were measured and correlated to with sea surface temperature (SST). SST was highest in July (29.6°C), and was lowest in January (16.3°C). Natal ring radius of statoliths was significantly lower in the individuals hatched in July and August (p<0.05), but no significant difference among the other months. The mean first 30 incremental width was significantly narrower in the individuals hatched in January and February but significantly wider in May (p<0.05). The mean first 30 days statolith incremental width was positive corresponded to temperature, but not in the hottest June and July. Therefore, higher temperature may inhibit their growth. A total of 65 statoliths elemental composition of Uroteuthis edulis at paralarval stage were qualified. The ranged of each elemental ratio were Sr/Ca: 3.34-12.09 mmol•mol-1, Ba/Ca: 1.3-39.59 µmol•mol-1, Mg/Ca: 1.15-113.54 mmol•mol-1, Fe/Ca: 86.49-1242.82 µmol•mol-1, Zn/Ca: 32.55-2983.12 µmol•mol-1, Cu/Ca: 6.81-763.52 µmol•mol-1, K/Ca: 1.16-113.81 mmol•mol-1, Pb/Ca: 0.09-32.23 µmol•mol-1. The elemental signatures of statolith can discriminate the individuals from spring cohort (January to August) to autumn cohort (September to December) by using principal component analysis (PCA). Overall, 87.7% individuals can correctly be classified between spring and autumn cohorts by using discriminant function analysis (DFA). The differences of trace elements of statolith might can from different chemical signature in water masses. It inferred that the early life history individuals of spring cohort lived habitat closer to continentally sourced China Costal Current, while autumn cohort inhabit in off-shored Kuroshio Current. In statolith microstructure, the natal ring radius has no significant difference between cohorts. In the monthly incremental width, statolith incremental width has no significant difference (p>0.05) for the first 60 days, but spring cohort grew significantly higher than autumn cohort at 61 to 150 days by analysing statolith incremental width (p<0.05). There had no significant difference after 150 days (p>0.05). Therefore, by using the incremental width per 30 days, swordtip squids growth faster in spring than autumn cohort because of higher temperature in the ambient water.
| Identifer | oai:union.ndltd.org:TW/102NTOU5451031 |
| Date | January 2014 |
| Creators | Hsu, Zhi-Zheng, 徐至正 |
| Contributors | Wang, Chai-Hui, 王佳惠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 56 |
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