Corresponding author: Mitsuharu Yagi ( yagi@kyudai.jp ) Academic editor: Alexei Orlov
© 2021 Mitsuharu Yagi.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Yagi M (2021) Short-term change in fish assemblages after the passage of a typhoon in a temperate, coastal bay. Acta Ichthyologica et Piscatoria 51(2): 175-183. https://doi.org/10.3897/aiep.51.63622
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To study the effects of a typhoon on a temperate, coastal bay community, the species composition, catch amount, and diversity of epipelagic fish assemblages were investigated. Fish samples were taken from catches of a purse seine fishery in Tachibana Bay, Japan between May and July 2011, covering before and after the passage of a typhoon in the area. Although major changes in total catch amount were not observed before and after the passage of the typhoon, the abundance of the Japanese anchovy, Engraulis japonicus Temminck et Schlegel, 1846, markedly decreased and bycatch of species increased, accompanied by increasing levels of diversity of the fish assemblage. Multivariate analysis showed that community differences before and after the passage were quantitative rather than qualitative. Comparisons in total length frequencies between the two periods indicated that specimens of the species compared were bigger in size for Trachurus japonicus (Temminck et Schlegel, 1844) and smaller for E. japonicus in the “after” period. These results suggest that the passage of the typhoon triggered not only interspecific faunal change but also intraspecific recruitment shifts in and around the bay.
bycatch, diversity, fish assemblage, migration, purse seine fishery, typhoon
The effects of hurricanes, typhoons (also termed tropical cyclones), and tropical storms, are major sources of physical disturbance to shallow water communities, affecting geological features (
It has been suggested that global warming may increase the frequency of strong typhoons (
On 26 June 2011, the typhoon MEARI (international number: 1105) passed approximately 500 km offshore of the west coast of Kyushu, Japan (Fig.
Tachibana Bay is located in the southern part of Nagasaki Prefecture, Kyushu, Japan. The northern and southern sides of this bay are enclosed by the Nagasaki and the Shimabara peninsulas, and the bay is connected to the Ariake Sound in the east, and exposed to the East China Sea in the west (Fig.
Best track data of MEARI (1105) in 2011 from the Regional Specialized Meteorological Center (RSMC), Tokyo, Japan.
Date (June) | Time | Center position (DDM) Latitude and Longitude | Central pressure [hPa] | Maximum wind speed near the center [m•s–1] | Radius of area of winds [km] | |
25 m•s–1 | 15 m•s–1 | |||||
09 | 13°12′N, 129°18′E | 998 | 18 | – | NE: 440 SW: 280 | |
15 | 14°00′N, 128°54′E | 998 | 18 | – | NE: 440 SW: 280 | |
21 | 14°48′N, 128°42′E | 994 | 20 | – | E: 700 W: 370 | |
23 | 03 | 15°36′N, 128°24′E | 990 | 23 | – | E: 700 W: 370 |
09 | 16°36′N, 127°54′E | 985 | 25 | – | SE: 750 NW: 370 | |
15 | 17°24′N, 127°24′E | 985 | 25 | – | SE: 750 NW: 370 | |
21 | 18°12′N, 126°54′E | 985 | 25 | – | SE: 750 NW: 370 | |
24 | 03 | 19°18′N, 126°30′E | 985 | 25 | – | SE: 750 NW: 370 |
09 | 20°48′N, 126°00′E | 980 | 30 | 190 | SE: 750 NW: 440 | |
15 | 22°48′N, 125°18′E | 980 | 30 | 190 | SE: 750 NW: 440 | |
18 | 23°36′N, 125°00′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 | |
21 | 24°24′N, 124°30′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 | |
25 | 00 | 24°54′N, 124°06′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 |
03 | 25°30′N, 123°48′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 | |
06 | 26°00′N, 123°36′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 | |
09 | 26°36′N, 123°18′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 440 | |
15 | 27°42′N, 123°18′E | 975 | 30 | E: 220 W: 190 | SE: 750 NW: 370 | |
21 | 29°12′N, 124°06′E | 980 | 30 | 150 | SE: 700 NW: 370 | |
26 | 03 | 32°06′N, 124°42′E | 980 | 30 | 150 | SE: 700 NW: 370 |
09 | 35°06′N, 124°24′E | 980 | 30 | 150 | SE: 700 NW: 370 | |
15 | 36°48′N, 123°00′E | 980 | 30 | 130 | SE: 650 NW: 370 | |
21 | 37°06′N, 122°48′E | 980 | 30 | 130 | E: 600 W: 370 | |
27 | 03 | 37°30′N, 123°00′E | 985 | 25 | – | E: 560 W: 370 |
09 | 38°30′N, 124°18′E | 990 | 23 | – | 330 |
Six random sampling operations were carried out opportunistically before and after the passage of the typhoon MEARI from May to July in 2011. Each sample of approximately 3 kg was taken from the purse seine catches prior to the sorting procedure at the Kyodomari Port of Tachibana Bay. The fishing gear was approximately 380 m in length, 30 m in depth, and 6 mm in minimal stretched mesh size. Total catch amount, the number of hauls, and sea surface temperature of the fishing grounds on sampling days were collected from the fishing master of this fishery.
In the laboratory, fishes from each sample were counted and identified to the lowest possible taxonomic level. The total weight of each taxon was also recorded in 0.1 g order and the total length frequency for each species, except for Japanese anchovy, was measured from randomly chosen 100 individuals.
The total catch amount and abundance of the samples were expressed as the weight of fish per haul. To analyze the species composition per haul before and after the typhoon, the following indices were calculated: number of species, abundance (i.e., weight of fish) of E. japonicus and of bycatch species, Simpson’s reciprocal index (1∙D–1), Shannon–Wiener species diversity (H′). Simpson’s reciprocal index 1∙D–1 was calculated as:
where S is the number of species and pi is the ratio of abundance of occurrences of the ith species to that of total species in the sample. Similarly, H′ was derived by:
where H′ is the Shannon–Wiener function, S is the number of species and pi is the ratio of abundance of occurrences of the ith species to that of total species in the sample. Both indices 1∙D–1 and H′ reflect not only species richness but also provide an index of the evenness of a community (
The mean values of the pooled data from the 3 purse seine fishing samples carried out ‘before’ and in the 3 samples ‘after’ the passage of the typhoon of total catch amount, abundance, and diversity for the community were compared by student t-test. Mann–Whitney U test was used to compare the total lengths of three species, Engraulis japonicus, Trachurus japonicus (Temminck et Schlegel, 1844), and Sarda orientalis (Temminck et Schlegel, 1844) (for which the data greater than two individuals were recorded in both ‘before’ and ‘after’ the typhoon) between the two sampling periods (P < 0.05).
The distribution of sea surface temperature data in Tachibana Bay, Kyushu, Japan is presented in Fig.
Changes in sea surface temperature and total catch amount during the experimental period in Tachibana Bay, Kyushu, Japan in 2011. A: Observed maximum and minimum sea surface temperature in the fishing ground, B: Total catch amount per haul, C: Mean total catch amount between ‘before’ and ‘after’ the passage of the typhoon. Data are means ± S.D. Arrows indicate the passage of the typhoon, A1~B3 indicate sample numbers and numbers in parentheses indicate dates.
Ratios of the number of individuals and of the abundance of bycatch species such as T. japonicus and S. orientalis abruptly increased just after the passage of the typhoon, and E. japonicus decreased (Fig.
Changes in species composition of the fish community during the period before (A1, A2, and A3) and after (B1, B2, and B3) the passage of the typhoon in Tachibana Bay, Kyushu, Japan. Percentages of the Japanese anchovy Engraulis japonicus (grey) and bycatch species, based on A: The number of individuals and B: Total wet weight of the species sampled (abundance) data.
Several descriptors of the fish community are shown in Fig.
Comparisons of several descriptors of the fish community between the two sampling periods ‘before’ and ‘after’ the passage of the tropical cyclone (*P < 0.05, **P < 0.01, student-t test). A: Number of species, B: Abundance (wet weight) of the Japanese anchovy Engraulis japonicus, C: Simpson’s reciprocal index 1∙D–1, D: Shannon–Weiner species diversity H′ (log 2). Data are means ± SD.
The classification dendrogram showed two defined clusters corresponding to the ‘before’ and ‘after’ periods, except for one sample (B3), at similarity levels of 52% and 74%, respectively (Fig.
Comparisons in total length frequencies between the two periods indicated that specimens of the species compared were not significantly different in size for S. orientalis (P = 0.68; Fig.
In the presently reported study, although major changes in the total catch amount per haul obtained from purse seine catches were not observed before and after the passage of the typhoon, the abundance of E. japonicus markedly decreased and that of bycatch species such as T. japonicus and S. orientalis increased in the ‘after’ period, accompanied by increasing levels of diversity in the fish assemblage. Furthermore, changes in total length frequencies of two fish species (T. japonicus and E. japonicus) occurred, respectively. These results support the hypothesis that the typhoon was likely to have changed the structure and spatial organization of multispecies aggregations of the fish community in the temperate, coastal bay.
An explanation for changes in fish assemblages could be that typhoon-induced forces affected the fish distribution. Typhoons have both direct and indirect effects on the distribution of fish species (
Indirect effects could be caused by changes in abiotic factors, such as temperature, salinity, and turbidity of seawater. The main parameter known to affect the spatial organization of coastal communities is the temperature (
Although multivariate analysis showed that the overall changes in community structure between the two periods are quantitative rather than qualitative, changes in total length frequencies between the two periods of two fish species may be thought of as qualitative. In this study, the mean total length for E. japonicus decreased from 98 mm (sub-adults) to 64 mm (juveniles) in the period after the passage of the typhoon. E. japonicus generally spawn from spring to autumn, resulting in the occurrence of several seasonal cohorts (
Finally, before–after comparisons have an advantage over those involving impact since it is easier to eliminate the factor of spatial variability. However, this type of comparison might be sensitive to seasonal and inter-annual variability (
I thank H. Takayama for providing constructive information prior to publication. I also am grateful to the three anonymous referees involved for providing excellent comments.
This research work was supported by the Human Resource Development Program (Ministry of Education, Culture, Sports, Science, and Technology, Japan; Marine Cybernetics For Fisheries Innovation).