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Claassens L, Harasti D. Life history and population dynamics of an endangered seahorse (Hippocampus capensis) within an artificial habitat. JOURNAL OF FISH BIOLOGY 2020; 97:974-986. [PMID: 32621517 DOI: 10.1111/jfb.14452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/18/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
Species-specific life-history information is critical for successful conservation, particularly in establishing an accurate baseline status. Obtaining such information is challenging for most species, but in particular for rare and threatened marine species. To facilitate future conservation of the endangered Knysna seahorse (Hippocampus capensis) this study aimed to determine important life-history information for this species. Visible implant fluorescent elastomer (VIFE) tags were used to mark 78 seahorses within a residential marina estate in the Knysna estuary, South Africa, in February 2018. Using a mark-resight approach, the size and movement patterns of the population and growth rate of seahorses were determined over a 14-month period. The closed population estimate for H. capensis, within Thesen Islands Marina, was estimated to be 134 (118-152 95% C.I.) in February 2018 compared to only 72 (48-108 95% C.I.) in February 2019. The species showed rapid initial growth with males and females having similar rates of growth based on the specialised von Bertalanffy growth function model. The importance of Reno mattresses as a habitat for H. capensis was confirmed based on the high abundance and site fidelity of the population, which emphasises the conservation potential of heavily modified environments for threatened seahorse species. The use of VIFE tags was deemed effective in studying this endangered seahorse and allowed the collection of important information for this species which can be used in future Red List assessments and conservation actions.
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Affiliation(s)
- Louw Claassens
- Department of Zoology & Entomology, Rhodes University, Grahamstown, Republic of South Africa
- Knysna Basin Project, Knysna, Republic of South Africa
| | - David Harasti
- Fisheries Research, NSW Department of Primary Industries, Taylors Beach, New South Wales, Australia
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Masonjones H, Rose E, Elson J, Roberts B, Curtis-Quick J. High density, early maturing, and morphometrically unique Hippocampus erectus population makes a Bahamian pond a priority site for conservation. ENDANGER SPECIES RES 2019. [DOI: 10.3354/esr00949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Jiang H, Wang K, Fang Y, Chen J, Li Y, Xia G, Zhang Y, Liu Y, Ren C, Lin Q. Sex-biased regulation of respiratory burst, phagocytic activity and plasma immune factors in lined seahorse (Hippocampus erectus) after subchronic benzo[a]pyrene exposure. FISH & SHELLFISH IMMUNOLOGY 2019; 86:1162-1168. [PMID: 30599255 DOI: 10.1016/j.fsi.2018.12.068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/22/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
Both wild and aquacultured seahorses are currently under great threat from marine pollution, notably from the potent contaminant and carcinogen benzo[a]pyrene (BaP). However, very little data are available regarding the immunomodulating effects of BaP in seahorses. Therefore, in this study, we exposed lined seahorses (Hippocampus erectus) for 7 d to BaP at three dosages (0.5, 5, and 50 μg/L) to evaluate sexual dimorphism in immune response. We measured eight immune parameters in the blood, including respiratory burst (RB), phagocytic activity (PA), monocytes/leucocytes, immunoglobulin M, complement 3, complement, interferon-a, and interleukin-2. Male seahorses had significantly higher parameters than females, except in terms of monocytes/leucocytes (P < 0.05). Although flow cytometry showed that RB and PA variation per BaP dose were roughly similar across sexes, RB and PA exhibited distinct patterns. Additionally, fluorescence intensity and leucocyte percentage were positively correlated in PA but not RB for all treatment and sex combinations. Through ELISA, we showed that the other six parameters had complex responses that nevertheless varied in a BaP-dosage and sex-dependent manner. Overall, adult male seahorses had higher immunocompetence than females before BaP exposure, and sexual dimorphism continued to be apparent during BaP exposure. Furthermore, all eight parameters were sensitive to BaP. Based on these results, we highly recommend H. erectus as a sentinel species for crude contamination, whereas PA and RB are valuable bioindicators of marine contaminants such as BaP.
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Affiliation(s)
- Han Jiang
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Kai Wang
- School of Agriculture, Ludong University, Yantai, 264025, China.
| | - Yan Fang
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Jun Chen
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Yanmin Li
- School of Life Sciences, Ludong University, Yantai, 264025, China
| | - Guangbo Xia
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Yingfeng Zhang
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Yu Liu
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Chuanbo Ren
- Shandong Provincial Key Laboratory of Restoration for Marine Ecology, Shandong Marine Resource and Environment Research Institute, Yantai, 264006, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
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