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Natural populations of shipworm larvae are attracted to wood by waterborne chemical cues.

Toth GB, Larsson AI, Jonsson PR, Appelqvist C - PLoS ONE (2015)

Bottom Line: Natural populations of teredinid larvae were significantly more abundant close to wooden structures enclosed in plankton net compared to empty control nets, clearly showing that shipworm larvae can sense and respond to chemical cues associated with suitable settling substrate in the field.However, the flume experiments, using ecologically relevant flow velocities, showed that the boundary layer around experimental wooden panels was thin and that the mean flow velocity exceeded larval swimming velocity approximately 5 mm (≈ 25 larval body lengths) from the panel surface.Therefore, we conclude that the scope for remote detection of waterborne cues is limited and that the likely explanation for the higher abundance of shipworm larvae associated with the wooden panels in the field is a response to a cue during or after attachment on, or very near, the substrate.

View Article: PubMed Central - PubMed

Affiliation: University of Gothenburg, Department of Biological and Environmental Sciences-Tjärnö, Strömstad, Sweden.

ABSTRACT
The life cycle of many sessile marine invertebrates includes a dispersive planktonic larval stage whose ability to find a suitable habitat in which to settle and transform into benthic adults is crucial to maximize fitness. To facilitate this process, invertebrate larvae commonly respond to habitat-related chemical cues to guide the search for an appropriate environment. Furthermore, small-scale hydrodynamic conditions affect dispersal of chemical cues, as well as swimming behavior of invertebrate larvae and encounter with potential habitats. Shipworms within the family Teredinidae are dependent on terrestrially derived wood in order to complete their life cycle, but very little is known about the cues and processes that promote settlement. We investigated the potential for remote detection of settling substrate via waterborne chemical cues in teredinid larvae through a combination of empirical field and laboratory flume experiments. Natural populations of teredinid larvae were significantly more abundant close to wooden structures enclosed in plankton net compared to empty control nets, clearly showing that shipworm larvae can sense and respond to chemical cues associated with suitable settling substrate in the field. However, the flume experiments, using ecologically relevant flow velocities, showed that the boundary layer around experimental wooden panels was thin and that the mean flow velocity exceeded larval swimming velocity approximately 5 mm (≈ 25 larval body lengths) from the panel surface. Therefore, we conclude that the scope for remote detection of waterborne cues is limited and that the likely explanation for the higher abundance of shipworm larvae associated with the wooden panels in the field is a response to a cue during or after attachment on, or very near, the substrate. Waterborne cues probably guide the larva in its decision to remain attached and settle, or to detach and continue swimming and drifting until the next encounter with a solid substrate.

No MeSH data available.


Related in: MedlinePlus

Laboratory flume experiment.Results from laser induced fluorescence (LIF) recordings on dye solution diffusing out of wooden panels. The fluorescent dye mimics any water soluble chemical that might act as attractive cues. A) Instantaneous cue distribution around the wooden panel at a free stream velocity of 1 cm s-1 with a high concentration diffusive boundary layer (DBL) on the panel surface and filaments of lower concentration transported from the DBL into the surrounding water. B) The maximum vertical distribution of cue filaments above the panel surface in the three tested free stream velocities; thin lines also show the DBL thickness for comparison. C) Average thickness of DBL as a function of free stream velocity and distance from the leading edge, i.e. upstream end of panel.
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pone.0124950.g004: Laboratory flume experiment.Results from laser induced fluorescence (LIF) recordings on dye solution diffusing out of wooden panels. The fluorescent dye mimics any water soluble chemical that might act as attractive cues. A) Instantaneous cue distribution around the wooden panel at a free stream velocity of 1 cm s-1 with a high concentration diffusive boundary layer (DBL) on the panel surface and filaments of lower concentration transported from the DBL into the surrounding water. B) The maximum vertical distribution of cue filaments above the panel surface in the three tested free stream velocities; thin lines also show the DBL thickness for comparison. C) Average thickness of DBL as a function of free stream velocity and distance from the leading edge, i.e. upstream end of panel.

Mentions: From instantaneous intensity images of the LIF recordings (Fig 4A) average and SD images were produced using the DaVis 8.2.0 software. The maximum vertical distribution of the dye filaments above the panel surface (extension of the cue "plume") in the different free stream velocities could most easily be derived from the SD images and are presented in Fig 4B. Below these lines approaching larvae could encounter attractive cue filaments. The diffusive boundary layer (DBL) on top of the wooden panels could clearly be distinguished on images from the LIF recordings (Fig 4A). The high concentration of Rhodamin dye in the DBL is shown as a white stripe of high fluorescing intensity on the panel surface. Measurements of the thickness of the DBL were done on average intensity images from the different free stream velocities. As expected, the DBL thickness decreased with free stream velocity although the difference between 3 and 5 cm s-1 is minor. The average DBL thickness also varied along the panel surface (Fig 4C), which can be explained by the flow pattern around the panels measured by PIV.


Natural populations of shipworm larvae are attracted to wood by waterborne chemical cues.

Toth GB, Larsson AI, Jonsson PR, Appelqvist C - PLoS ONE (2015)

Laboratory flume experiment.Results from laser induced fluorescence (LIF) recordings on dye solution diffusing out of wooden panels. The fluorescent dye mimics any water soluble chemical that might act as attractive cues. A) Instantaneous cue distribution around the wooden panel at a free stream velocity of 1 cm s-1 with a high concentration diffusive boundary layer (DBL) on the panel surface and filaments of lower concentration transported from the DBL into the surrounding water. B) The maximum vertical distribution of cue filaments above the panel surface in the three tested free stream velocities; thin lines also show the DBL thickness for comparison. C) Average thickness of DBL as a function of free stream velocity and distance from the leading edge, i.e. upstream end of panel.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430175&req=5

pone.0124950.g004: Laboratory flume experiment.Results from laser induced fluorescence (LIF) recordings on dye solution diffusing out of wooden panels. The fluorescent dye mimics any water soluble chemical that might act as attractive cues. A) Instantaneous cue distribution around the wooden panel at a free stream velocity of 1 cm s-1 with a high concentration diffusive boundary layer (DBL) on the panel surface and filaments of lower concentration transported from the DBL into the surrounding water. B) The maximum vertical distribution of cue filaments above the panel surface in the three tested free stream velocities; thin lines also show the DBL thickness for comparison. C) Average thickness of DBL as a function of free stream velocity and distance from the leading edge, i.e. upstream end of panel.
Mentions: From instantaneous intensity images of the LIF recordings (Fig 4A) average and SD images were produced using the DaVis 8.2.0 software. The maximum vertical distribution of the dye filaments above the panel surface (extension of the cue "plume") in the different free stream velocities could most easily be derived from the SD images and are presented in Fig 4B. Below these lines approaching larvae could encounter attractive cue filaments. The diffusive boundary layer (DBL) on top of the wooden panels could clearly be distinguished on images from the LIF recordings (Fig 4A). The high concentration of Rhodamin dye in the DBL is shown as a white stripe of high fluorescing intensity on the panel surface. Measurements of the thickness of the DBL were done on average intensity images from the different free stream velocities. As expected, the DBL thickness decreased with free stream velocity although the difference between 3 and 5 cm s-1 is minor. The average DBL thickness also varied along the panel surface (Fig 4C), which can be explained by the flow pattern around the panels measured by PIV.

Bottom Line: Natural populations of teredinid larvae were significantly more abundant close to wooden structures enclosed in plankton net compared to empty control nets, clearly showing that shipworm larvae can sense and respond to chemical cues associated with suitable settling substrate in the field.However, the flume experiments, using ecologically relevant flow velocities, showed that the boundary layer around experimental wooden panels was thin and that the mean flow velocity exceeded larval swimming velocity approximately 5 mm (≈ 25 larval body lengths) from the panel surface.Therefore, we conclude that the scope for remote detection of waterborne cues is limited and that the likely explanation for the higher abundance of shipworm larvae associated with the wooden panels in the field is a response to a cue during or after attachment on, or very near, the substrate.

View Article: PubMed Central - PubMed

Affiliation: University of Gothenburg, Department of Biological and Environmental Sciences-Tjärnö, Strömstad, Sweden.

ABSTRACT
The life cycle of many sessile marine invertebrates includes a dispersive planktonic larval stage whose ability to find a suitable habitat in which to settle and transform into benthic adults is crucial to maximize fitness. To facilitate this process, invertebrate larvae commonly respond to habitat-related chemical cues to guide the search for an appropriate environment. Furthermore, small-scale hydrodynamic conditions affect dispersal of chemical cues, as well as swimming behavior of invertebrate larvae and encounter with potential habitats. Shipworms within the family Teredinidae are dependent on terrestrially derived wood in order to complete their life cycle, but very little is known about the cues and processes that promote settlement. We investigated the potential for remote detection of settling substrate via waterborne chemical cues in teredinid larvae through a combination of empirical field and laboratory flume experiments. Natural populations of teredinid larvae were significantly more abundant close to wooden structures enclosed in plankton net compared to empty control nets, clearly showing that shipworm larvae can sense and respond to chemical cues associated with suitable settling substrate in the field. However, the flume experiments, using ecologically relevant flow velocities, showed that the boundary layer around experimental wooden panels was thin and that the mean flow velocity exceeded larval swimming velocity approximately 5 mm (≈ 25 larval body lengths) from the panel surface. Therefore, we conclude that the scope for remote detection of waterborne cues is limited and that the likely explanation for the higher abundance of shipworm larvae associated with the wooden panels in the field is a response to a cue during or after attachment on, or very near, the substrate. Waterborne cues probably guide the larva in its decision to remain attached and settle, or to detach and continue swimming and drifting until the next encounter with a solid substrate.

No MeSH data available.


Related in: MedlinePlus