Seasonal and habitat structures of crustacean decapod assemblages associated withZostera marinabeds in northern Jinhae Bay, Korea

Abstract

Crustacean decapod assemblages were surveyed in Zostera marina beds adjacent to tidal flats (ET) and rocky shore (ER), and in unvegetated habitats (UV). Decapod samples were collected monthly throughout 2002 using a small beam trawl from northern Jinhae Bay, Korea. Water temperature, salinity, eelgrass biomass, sediment composition and organic matter were also monitored to assess any correlation between environmental variables and decapod fauna. A total of 31 decapod species belonging to five taxa (three prawns, 13 caridean shrimps, one hermit crab, one mud shrimp and 13 crabs) were collected at three different habitats. To assess variations in decapod assemblages in relation to habitat type and season, various multivariate analyses were used. The dominant caridean shrimps were Palaemon macrodactylus, Alpheus digitalis and Crangon uritai, and the dominant crabs were Charybdis japonica, Hemigrapsus penicillatus and Charybdis bimaculata. The number, abundance and diversity of decapod species varied greatly with habitat type and season, peaking in eelgrass beds and during spring, and showing the lowest catch rate in unvegetated habitat and during winter months. The nMDS ordination and multivariate analyses revealed that habitat type and season were determinant factors affecting the structure of decapod assemblages. Seasonal shifts in the abundance of decapods corresponded with changes in eelgrass biomass and loss on ignition (LOI), but not with water temperature or salinity.

Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

“…Similar community structures from other South Korean regions were reported. Heptacarpus, Latreutes, Eualus, and Palaemon were the dominant shrimp genera at the seagrass habitats in Kwang Bay and Jinhae Bay [4,36,59]. Charybdis (Charybdis) japonica, Pu.…”

“…quadridens, and Te. acutidens were the common crab species at the seagrass beds of Jinhae Bay, but they were not in adjacent unvegetated areas of the bay [36]. Compared with seagrass beds of temperate regions worldwide, the genera Eualus, Heptacarpus, and Latreutes were the principally North Pacific caridean genera often abundant in Zostera meadows [42].…”

“…Bloomfield and Gillanders [35] reported similar faunal assemblages between non-vegetated and seagrass habitats in southern Australia, with the caveat of higher loss rates of species richness and abundance in seagrass habitats. More recently, Park and Kwak [36] showed that seagrass beds adjacent to both tidal flats and rocky shores supported greater decapod abundances and diversities than adjacent unvegetated habitats. The importance of large seagrass beds to abundance and diversity [36][37][38] may be due to the high abundances of eelgrass residents [39].…”

“…More recently, Park and Kwak [36] showed that seagrass beds adjacent to both tidal flats and rocky shores supported greater decapod abundances and diversities than adjacent unvegetated habitats. The importance of large seagrass beds to abundance and diversity [36][37][38] may be due to the high abundances of eelgrass residents [39]. Comparative studies of decapod assemblages between vegetated and unvegetated seagrass habitats have shown bare habitats with fewer species [36] and associated with considerable diel and seasonal variations in abundance and assemblage structure [36,[40][41][42].…”

“…Although a number of studies comparing fish and decapod assemblages in seagrass meadows have been conducted globally [39,40,[46][47][48][49][50], few such studies have been conducted in the eelgrass beds of South Korean waters. Of the few, the focus was limited to estimating the effects on fish communities [36,43,51]. Studies on the effects on decapod diversity, including assessment of bottom sediment structure, presence of seagrasses, and hydrodynamic features, such as water temperature, tidal current, and seasonal storms, might provide key insight into the factors influencing the maintenance of decapod assemblages [52].…”