Table 1.
Opportunistic observations of actively walking and non-walking epibenthic hard clams, Mercenaria mercenaria, made while diving in the Peconic Bays, New York, USA, June 2007 –June 2016.
Table 2.
Summary of factors hypothesized to affect specific metrics of observed hard clam walking behavior in the Peconic Bays, New York, USA.
Table 3.
Summary of factors hypothesized to differ between adjacent (~50–60 m apart) areas at the East Marion site where hard clam walking was frequently observed (‘walking area’) versus rarely observed (‘non-walking’ area).
Fig 1.
Hard clam, Mercenaria mercenaria, walking at East Marion, New York, USA.
(A) Active walker illustrating typical shell orientation: ligament parallel to sediment surface, siphon above sediment in furrow. (B) Active walker with freshly excavated trail (furrow). (C) Non-walking clam lying on sediment surface, next to active walker. (D) Active walker at end of semi-circular trail. (E) Epibenthic clams, with posterior ends (where siphons are located) adjacent to one another.
Fig 2.
Bar plots of mean (±1 standard error of the mean, SE) Mercenaria mercenaria density versus site/walking designation in Orient Harbor, New York, USA.
(A) Total (epibenthic + endobenthic) clam density. (B) Surface (epibenthic) clam density. All densities quantified at the East Marion site, except where noted as * (= Peter’s Neck site). W = walking clams, in ‘walking’ areas; NW = non-walking clams, in ‘non-walking’ area; WNW = non-walking clams in ‘walking’ area.
Fig 3.
Morisita’s Index for Mercenaria mercenaria versus site/walking designation in Orient Harbor, New York, USA.
W = walking clams, in ‘walking’ areas; NW = non-walking clams, in ‘non-walking’ area; WNW = non-walking clams in ‘walking’ area. Dashed line demarcates transition from a random (IM = 1) to an aggregated distribution (IM > 1); asterisk denotes a significant χ2 test: p = 0.001.
Fig 4.
Bar plots of mean (±1 standard error of the mean, SE) nearest neighbor distances of Mercenaria mercenaria at East Marion, New York, USA.
(A) endo- + epibenthic clams and (B) epibenthic clams only. W = walking clams, in ‘walking’ area; NW = non-walking clams, in ‘non-walking’ area; WNW = non-walking clams in ‘walking’ area. Different letters above bars represent significantly different densities at p < 0.05.