Spatial and temporal patterns of abundance of coral reef gobies (Teleostei: Gobiidae)
This study investigated the spatial and temporal patterns of abundance of four substratum-associated species of Gobiidae on a heterogeneous reef flat comprised of four distinct habitat zones, and examined microhabitat use within each zone. Asterropteryx semipunctatus had the widest distribution and was the most abundant species in each habitat zone, followed by Amblygobius bynoensis, Valenciennea muralis and Amblygobius phalaena. Significant temporal and spatial differences in mean density were evident. The highest density of A. semipunctatus (312 individuals 10 m–2) was recorded in a habitat zone dominated by algal-covered rubble, whereas A. bynoensis and V. muralis were most abundant (mean summer density 5·5–5·8 individuals 10 m–2) in habitats containing both sand and hard substrata. In contrast, A. phalaena was uncommon (mean density ≤ 0·4 individuals 10 m–2) in all four habitat zones. Significant seasonal differences in abundance were due to the large influx of recruits in summer. Ontogenetic shifts in habitat use were not evident at either the macrohabitat (i.e. among habitat zones) or microhabitat scale (i.e. substratum use within zones). At the microhabitat scale, V. muralis consistently exhibited a strong positive association with sand and was rarely associated with hard substrata. In contrast, the two Amblygobius species were commonly associated with both sand and hard substrata, but patterns of microhabitat use differed among habitat zones. Substratum composition at the microhabitat scale may influence spatial patterns of abundance at larger spatial scales by providing essential resources and, or influencing carrying capacity and predation risk.
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