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

Decapod assemblages in Zostera marina beds from two bays adjacent to unvegetated habitats were investigated to assess their influence on decapod assemblages. Thirty-eight decapod species belonging to four taxa were collected using a small beam trawl at four habitat types from two different locations off the coast of Namhae Island, South Korea. Dominant decapod taxon at all habitats was the caridean shrimps, with Eualus leptognathus, Heptacarpus pandaloides, Latreutes anoplonyx, La. Laminirostris, and Palaemon macrodactylus being the most abundant caridean species. Crabs were characterized with the highest biomass, but with moderate species richness and abundance. Penaeoid and sergestoid shrimps only accounted for <1% of the total decapod abundance. The number of species and their abundance of decapod assemblages varied greatly by habitat type, season, and diel patterns, but not diversity. Species number and abundance peaked in seagrass beds of southern exposed bays during the autumn and were lowest in unvegetated habitats during the summer months. Diel decapod catch rates were higher at night. Dense seagrass vegetation and nighttime supported higher decapod mean densities, but not species richness and diversity. Multivariate analyses revealed that habitat type and season significantly affected the structure of decapod assemblages, but diel patterns had a minor influence. Among decapod species, Pa. macrodactylus and Pugettia quadridens characterized the decapod assemblages in seagrass beds at the northern semi-closed bay, while Telmessus acutidens, Crangon affinis, Cr. hakodatei, Charybdis (Charybdis) japonica, and Portunus sanguinolentus were significantly associated with both vegetated and unvegetated habitats at the southern exposed bay, with the former two species more abundant during the colder season.

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

Decapod assemblages in Zostera marina beds from two bays adjacent to unvegetated habitats were investigated to assess their influence on decapod assemblages. Thirty-eight decapod species belonging to 4 taxa were collected using a small beam trawl at four habitat types from two different locations off the coast of Namhae Island, southern Korea. Dominant decapod taxon at all habitats was the caridean shrimps, with Eualus leptognathus, Heptacarpus pandaloides, Latreutes anoplonyx, La. laminirostris and Palaemon macrodactylus being the most abundant caridean species. Crabs were characterized by the highest biomass, but moderate species richness and abundance. Penaeoids and sergestoids shrimps only accounted for &lt;1% of the total decapod abundance. The number of species, their abundance, and the diversity of decapod assemblages varied greatly by habitat type, season, and diel patterns. Species number and abundance peaked in seagrass beds of southern exposed bays during the autumn, and were lowest in unvegetated habitats during the summer months. Diel decapod species and catch rates were higher at night. Dense seagrass vegetation and nighttime supported greater decapod species richness and higher mean densities, but not diversity. Multivariate analyses revealed that habitat type and season significantly affected the structure of decapod assemblages, but diel patterns had a minor influence. Among decapod species, Pa. macrodactylus and Pugettia quadridens characterized the decapod assemblages in seagrass beds at the northern semi-closed bay, while Telmessus acutidens, Crangon affinis, Cr. hakodatei, Charybdis japonica and Portunus sanguinolentus were significantly associated with both vegetated and unvegetated habitats at the southern exposed bay, with the former two species more abundant during winter and spring.

Seasonal and habitat structures of crustacean decapod assemblages associated with Zostera marina beds in northern Jinhae Bay, Korea

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.

Decoupling the response of an estuarine shrimp to architectural components of habitat structure

In order to explore biotic attraction to structure, we examined how the amount and arrangement of artificial biotic stalks affected responses of a shrimp,Palaemon macrodactylus, absent other proximate factors such as predation or interspecific competition. In aquaria, we tested the effect of differing densities of both un-branched and branched stalks, where the amount of material in the branched stalk equaled four-times that of the un-branched. The results clearly showed that it was the amount of material, not how it was arranged, that elicited responses from shrimp. Also, although stalks were not purposefully designed to mimic structural elements found in nature, they did resemble biogenic structure such as hydroids, algae, or plants. In order to test shrimp attraction to a different, perhaps more unfamiliar habitat type, we examined responses to plastic “army men.” These structural elements elicited similar attraction of shrimp, and, in general, shrimp response correlated well with the fractal dimension of both stalks and army men. Overall, these results indicate that attraction to physical structure, regardless of its nature, may be an important driver of high abundances often associated with complex habitats.

Use of rocky intertidal pools by shrimp species in a temperate area

Rocky shores are among the most-intensively studied ecosystems, however, tidal pools remain relatively understudied. This study aims to investigate the habitat use and dynamics of the shrimp species that occur in tidal pools of a North-eastern Atlantic coast, the Portuguese coast, in particular species composition, abundance, seasonality and size structure. Shrimps were sampled monthly from six tidal pools for one year, in the west Portuguese coast. Species diversity was much higher than that found in previous studies, in other parts of the world. The shrimp population comprised 8 species: the European rock shrimp, Palaemon elegans, the common prawn, Palaemon serratus, the Atlantic ditch shrimp, Palaemon varians, the Baltic prawn, Palaemon adspersus, the Oriental shrimp, Palaemon macrodactylus and the relatively rare shrimps Eualus sollaudi, Eualus drachi and Caridion gordoni. Shrimp populations varied seasonally and among pools, with peak numbers in spring and summer. The most abundant species was P. elegans. P. elegans was present in all pools, throughout most of the year. Rare and exotic species were present mostly in spring-summer. Lower mean sizes of all shrimp were registered in the beginning of spring, most often in April or May, and gradually increased until winter. New-recruits of the most abundant species, P. elegans, generally entered the pools in spring and formed a high proportion of the population between April and August. They were responsible for the highest abundance peaks of shrimps occurring in the pools. The species richness and high numbers of juveniles occurring in tidal pools suggest that these environments may be nursery areas for coastal shrimp.