Regional and Seasonal Differences in Species Composition and Trophic Groups for Tidepool Fishes of a Western Pacific Island – Taiwan

Abstract

Spatial and temporal variations in the species composition of assemblages are common in many marine organisms, including fishes. Variations in the fish species composition of subtidal coral reefs have been well documented, however much less is known about such differences for intertidal fish assemblages. This is surprising, given that intertidal fishes are more vulnerable to terrestrial human disturbances. It is critical to evaluate the ecology and biology of intertidal fishes before they are severely impacted by coastal development, especially in developing countries such as those in the tropical western Pacific region where coastal development is rapidly increasing. In this study, we investigated the species composition, abundance, biomass and species number (richness) for intertidal fish assemblages in subtropical (northern) and tropical (southern) Taiwan across four seasons by collecting fishes from tidepools using clove oil. We also examined the gut contents of collected fishes to identify their trophic functional groups in order to investigate regional and seasonal variations for different trophic groups. We found significant differences in the species composition of tidepool fish assemblages between subtropical and tropical Taiwan. Bathygobius fuscus, Abudefduf vaigiensis and Istiblennius dussumieri were dominant species in subtropical Taiwan, whereas Bathygobius coalitus, Abudefduf septemfasciatus and Istiblennius lineatus were dominant in tropical Taiwan. Other species such as Bathygobius cocosensis, Abudefduf sordidus and Istiblennius edentulus were common in both regions. For trophic groups, omnivores and detritivores had or showed trends towards higher species numbers and abundances in the subtropical region, whereas herbivores, planktivores and general carnivores had or showed trends towards higher species numbers and biomass in the tropical region. Overall, many intertidal fish species and trophic groups showed differences in abundance, biomass and species number between subtropical and tropical Taiwan. Further studies on large scale geographical gradients in trophic groups and species compositions in the Indo-west Pacific region are encouraged to assist with ecosystem monitoring and assessment. Keywords: Intertidal fishes, spatio-temporal pattern, feeding guild, diet

Coastal development threatens Datan area supporting greatest fish diversity at Taoyuan Algal Reef, northwestern Taiwan

“…The same approach was also used to compare the diversity of the fish community at Taoyuan Algal Reef with that of other coastal locations previously sampled around Taiwan. Fish communities in the north (Keelung) and south (Kenting) of Taiwan were sampled between 2001 and 2002 from tidal pools using clove oil (Wen, Chen & Shao, 2018). Fish communities from the east (Hualien) and west (Dadu Wetland MPA) were sampled from estuaries using cast nets between 2014 and 2015 (Wen et al, unpublished data).…”

Quần xã cá vùng triều san hô chết ở vịnh Vân Phong

“…Sự thay đổi không gian theo đới triều có thể ảnh hưởng đến sự phong phú và phân bố của loài, trong đó sự phong phú về loài của Tạp chí Khoa học -Công nghệ Thủy sản Số 2/2022 cá vùng triều giảm dần từ vùng triều thấp đến vùng triều cao [33]. Tuy nhiên một số nghiên cứu khác lại cho thấy không có sự khác biệt rõ ràng về số lượng cá thể trung bình giữa các khu vực bãi triều, trong khi thành phần loài có sự khác biệt [23].…”