Invasion of Laguncula pulchella (Gastropoda: Naticidae) and predator–prey interactions with bivalves on the Tona coast, Miyagi prefecture, northern Japan

Chiba

2016

PLoS ONE

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We examined structural changes in the molluscan community for ten years (2001–2010) before and five years (2011–2015) after the 2011 Great East Japan Earthquake and subsequent tsunami around Matsushima Bay, Miyagi Prefecture, northeastern Japan. Before the earthquake and tsunami, Ruditapes philippinarum, Macoma incongrua, Pillucina pisidium, and Batillaria cumingii were dominant, and an alien predator Laguncula pulchella appeared in 2002 and increased in number. After the tsunami, R. philippinarum and M. incongrua populations quickly recovered in 2012, but P. pisidium and B. cumingii populations did not recover until 2015. By contrast, Musculista senhousia, Mya arenaria, Retusa sp., and Solen strictus were found in low densities before the tsunami, but they rapidly increased in abundance/number over five years after the tsunami. These results suggest that the molluscan community on the Tona Coast was drastically changed by the earthquake and tsunami, and some species mainly inhabiting the intertidal—subtidal zone may have increased in number because of land subsidence. We also emphasize that the seawall delayed recovery of the intertidal community after the earthquake and tsunami.

“…philippinarum and M . incongrua , resulting in a decline in these populations between 2002 and 2004 [11, 13, 14]. In contrast, the proportions of B .…”

Section: Resultsmentioning

confidence: 99%

Structural Changes in Molluscan Community over a 15-Year Period before and after the 2011 Great East Japan Earthquake and Subsequent Tsunami around Matsushima Bay, Miyagi Prefecture, Northeastern Japan

Chiba

2016

PLoS ONE

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“…pulchella individual was detected on the Tona Coast (see Sato et al . ; Chiba & Sato ). After 2005, the DI values for the smallest size class became much higher, suggesting that juveniles were frequently consumed by the naticid predator.…”

Section: Discussionmentioning

confidence: 96%

“…pulchella also had a top‐down effect on prey populations and bivalve community structure on the Tona Coast (Sato et al . ; Chiba & Sato ). A single L .…”

Section: Introductionmentioning

confidence: 96%

Invasion of a naticid predator and associated changes in death assemblages of bivalve prey in northern Japan: implications for palaeoecological studies

Chiba

2014

LET

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The recent invasion of a naticid predator (Laguncula pulchella) and associated changes in the death assemblages of bivalve prey (Ruditapes philippinarum) provide a baseline for interpreting predator–prey interactions in the fossil record. This article presents quantitative data on size‐frequency distributions (SFDs) of living and death assemblages, prey size selectivity and drillhole site selectivity from the Tona Coast, northern Japan. Before the appearance of the predator, the SFD of the death assemblage exhibited a right‐skewed platykurtic distribution, and there were very few predatory drillholes. Once the predator appeared, frequencies of predatory drillholes increased, particularly in the smallest size class (2–10 mm shell length). Furthermore, juvenile peaks in the SFDs of death assemblages sharpened, and thus, SFDs exhibited strongly right‐skewed leptokurtic distributions. These changes suggest that intense naticid predation precluded juvenile clams from growing to adulthood, and thus, many dead shells of juvenile clams were introduced into the sediment. The changes in SFDs may also indicate intensification of predation pressure in the fossil record. No temporal shifts in prey size selectivity and drillhole site selectivity were noted, despite substantial changes in the demographics of Ruditapes philippinarum. This suggests that lack of specific size classes of preferred prey species is unlikely to be a primary factor accounting for size mismatches between predator and prey, because, in such situations, naticid predators probably attack other prey species. Therefore, such a factor is unlikely to primarily explain the less stereotypical predatory behaviour (i.e. low prey size selectivity and low drillhole site selectivity), which has been frequently recognized in fossil assemblages. Such less stereotypical predatory behaviour in fossil assemblages is likely to be explained by other factors, such as the existence of multiple predator taxa and lack of specific size classes of all available prey.

“…Such size-dependent predation would affect the size composition of prey (Commito 1982). Moreover, L. pulchella feeds on other mollusks when the size of the R. philippinarum population decreases , Chiba & Sato 2013. Dead shells with drill holes observed in some bivalve species at Site H indicate the predation mortality caused by L. pulchella.…”

Section: Discussionmentioning

confidence: 99%

Abundance and body size of the moonsnail <i>Laguncula pulchella</i> in the Misuji River estuary, Seto Inland Sea, Japan: comparison with a population in northern Japan

Yoshida

Narita

et al. 2017

Plankton Benthos Res

Abstract:The moonsnail Laguncula pulchella (Naticidae, formerly known as Euspira fortunei) is an invasive species that has had a negative impact on the Manila clam (Ruditapes philippinarum) population in northern Japan. In southern Japan, few records of L. pulchella exist; furthermore, the knowledge concerning the ecology of this organism is currently limited. Unexpectedly, we found many L. pulchella individuals in the Misuji River estuary, located in Hiroshima in southern Japan, during May 2015. We conducted a field survey on the density and body size of L. pulchella at a tidal flat in the Misuji River estuary (Site H) and compared those to L. pulchella in Matsukawaura Lagoon, located in Fukushima in northern Japan (Site F). The adult population of L. pulchella in a clam fishing ground (40,500 m 2 ) at Site H was estimated to be 2,048 individuals in 2015. Densities of both surfaced individuals and egg collars of L. pulchella were lower at Site H than at Site F. Sizes of L. pulchella individuals and their egg collars as well as the somatic weight of the individuals at Site H were significantly smaller than those at Site F. These results suggest that the biological characteristics of L. pulchella largely differ between the two sites.