Impacts of the 2011 Tsunami on Sediment Characteristics and Macrozoobenthic Assemblages in a Shallow Eutrophic Lagoon, Sendai Bay, Japan

Abstract

A huge tsunami is one of the greatest disturbance events in coastal benthic communities, although the ecological consequences are not fully understood. Here we examined the tsunami-induced changes in the sediment environment and macrozoobenthic assemblage in a eutrophic brackish lagoon in eastern Japan. The 7.2-m-high tsunami completely replaced muddy sediment with drifting sea sand throughout the lagoon, leading to the drastic changes in quantity and quality of sedimental organic matters, sulfide contents, and sediment redox condition. Intensive physical stress devastated the benthic community, but the disappearance of sulfidic muddy bottoms significantly improved the habitat quality for macrozoobenthos. The re-established macrozoobenthic community after 5 months was characterized by (1) a 2-fold higher total density, but sharp declines in species richness, diversity, and evenness; (2) an increased density of opportunistic taxa (e.g., polychaete Pseudopolydora spp. and amphipod Monocorophium uenoi) in newly created sandy bottoms; and (3) disappearance of several dominant taxa including bivalves and chironomid larvae. These findings indicate that the sensitivity and recovery potential of macrozoobenthos were highly taxa-specific, which was closely related to the taxa’s ecological characteristics, including tolerance to physical disturbance, life-history traits, and life form. Our data revealed the rapid recolonization of opportunistic macrozoobenthos after a huge tsunami, which would contribute to the functional recovery of estuarine soft-bottom habitats shortly after a disturbance event.

Cosmopolitan or Cryptic Species? A Case Study ofCapitella teleta(Annelida: Capitellidae)

“…I sensu Grassle and Grassle (1976) from Massachusetts (USA) based on the karyotype, ability to interbreed, and lifehistory; this taxon has subsequently been reported from Japan in various ecological papers under the name Capitella sp. I (e.g., Tsutsumi, 2005;Tsutsumi et al, 2005a, b;Kinoshita et al, 2008) or C. teleta (Nishi et al, 2010;Kanaya, 2014;Kanaya et al, 2015). These records, together with reports from California and the Mediterranean , suggested that C. teleta is broadly distributed ( Fig.…”

“…jonesi (Hartman, 1959); C. minima Langerhans, 1880;and C. teleta (e.g., Kitamori, 1960;Imajima and Hartman, 1964;Imajima, 2015;Kanaya et al, 2015). Before C. teleta was described in 2009, most Capitella specimens from Japan were identified as C. capitata (e.g., Kitamori and Funae, 1959;Imajima and Hartman, 1964;Honma et al, 1974;Ueno and Yamamoto, 1982;Tsutsumi and Kikuchi, 1984;Tsutsumi, 1987;Tsutsumi et al, 1991).…”

Effects of sedimentary sulfide on community structure, population dynamics, and colonization depth of macrozoobenthos in organic-rich estuarine sediments

“…The water in the lagoon often becomes anoxic at night during the summer and fall (Kurihara et al 1997). Sediment in the inner portion is sulfidic and muddy (silt-clay N 50%), whereas it is sandier and oxidized near the levee (Kanaya et al 2015b). Macrozoobenthos rarely occur in the muddy sulfidic zone but densely colonize the sandy areas (Kanaya et al 2015b).…”

“…Organic-rich mud containing high levels of H 2 S was distributed in the northern subtidal portion of this lagoon (Kanaya and Kikuchi 2004;Kanaya et al 2015b). In our previous study, we investigated the effects of sedimentary H 2 S on the macrozoobenthic community structure in an in situ recolonization experiment using sediment with Marine Pollution Bulletin xxx (2016) xxx-xxx controlled H 2 S contents (Kanaya 2014).…”

The “tsunami break:” impact of the Great East Japan Earthquake and the accompanying tsunamis on the shell growth of the invasive clam-eating snail Laguncula pulchella

“…It caused massive tsunamis that struck northern Japan. The sandy and rocky shore habitats where marine organisms, including mollusks, live in the intertidal zone were drastically changed by the tsunamis, and marine ecosystems suffered great damage (Miura et al 2012Okoshi 2013Okoshi , 2015Okoshi , 2016Suzuki 2013;Tamaki and Muraoka 2013;Takami et al 2013;Urabe et al 2013;Kawamura et al 2014;Kanaya et al 2014Kanaya et al , 2015Abe et al 2015Abe et al , 2017Noda et al 2016;Noda and Iwasaki 2017;Muraoka et al 2017).…”