Blind dating—mate finding in planktonic copepods. II. The pheromone cloud of Pseudocalanus elongatus

Abstract

Receptive females of Pseudocalanus elongatus, like many other planktonic copepods, produce pheromones to signal their presence and position to males, and thus enhance the rate of mate encounter. By means of 3D video recordings we describe how a characteristic behaviour is elicited in males that encounter the pheromone signal of a female. For several minutes the male speeds around the female along zigzagged and looped swimming trails. Every 10 to 20 s he approaches the female, slows down, and makes physical contact with her. Between visits, the male makes long excursions that may take him up to 15 mm away from her. The multiple excursions define a near-spherical volume around the female within which he is capable of navigating back to her. During courtship the female hovers, but she frequently changes her body orientation and, thus, the direction of her feeding current, which also causes her to move a little. Due to this small-scale dance of the female, pheromones are constantly being spread in different directions and from constantly shifting positions. Based on male and female behaviour and simple advection-diffusion models, we characterise the pheromone plume surrounding the female as an almost spherical cloud with a very heterogeneous internal structure. This is very different from the long, distinct pheromone trails deposited by females of many cruising copepods and appears to be characteristic of hovering females. We estimate the encounter cross-section area of the pheromone plume of P. elongatus and find that it enhances the mate encounter probability by a factor of about 40, and we show that this area increases in proportion to the rate at which pheromones are released. We also show that pheromone clouds are affected by -but still quite robust to -turbulence, with the encounter cross section declining with the turbulent dissipation rate raised to a power of 1/2. The sensitivity of mate encounter rates to turbulence is similar among copepods that produce pheromone trails and pheromone clouds. KEY WORDS: Courting behaviour · Chemical signals · Sensitivity to turbulence · Scaling propertiesResale or republication not permitted without written consent of the publisher

The effect of mating behavior and temperature variation on the critical population density of a freshwater copepod

“…An alternative, more complex formulation (Kiørboe 2006) was less suitable because data for accurately estimating the stage-specific mortalities are not available for this or related species. An estimate of maximum population growth rate (R max ) cannot be obtained from established populations of H. shoshone (or many other alpine copepods) because this species is univoltine (producing resting eggs during the summer that hatch the following spring or remain in the egg bank) and because population density varies little from year to year.…”

“…Below this threshold, mate limitation is expected to result in a negative population growth rate. Mate limitation has been hypothesized to explain observed minimum population densities in other copepod species (Kiørboe 2006;Choi and Kimmerer 2008) and has been shown to contribute to the failure of H. shoshone populations to reestablish after fish disappearance (Sarnelle and Knapp 2004;Kramer et al 2008).…”

“…In a threedimensional (3D) habitat that is large relative to copepod body size, the rate of male-female encounters can limit population growth and persistence (Gerritsen 1980;Buskey 1998;Kiørboe 2006). Mechanistic models based on population growth rate and encounter rate predict a critical density threshold for copepod population viability (Gerritsen 1980;Kiørboe 2006).…”

Variability inCalanusspp. abundance on fine- to mesoscales in an Arctic fjord: implications for little auk feeding

“…mate localization, migration) operate on spatial scales of B10 (2 m (e.g. Pinel-Alloul 1995; Pitchford & Brindley 2001;Saito & Kiørboe 2001;Kiørboe et al 2005;Weimerskirch 2007). Other ecologically significant processes such as predatorÁprey interactions can operate on a wide range of scales, from the millimetre scale covered by foraging fish larvae to the 100 km covered by right whales feeding on copepods (Beardsley et al 1996;Pendleton et al 2009;Young et al 2009).…”

Hydrocarbon Contamination and the Swimming Behavior of the Estuarine Copepod Eurytemora affinis

“…Despite the central role played by copepods in aquatic ecosystems (Schmitz, 2008;Matthews et al, 2011), the amount of work devoted to copepod chemoreception (e.g. Doall et al, 1998;Bagøien & Kiørboe, 2005;Goetze & Kiørboe, 2008;Yen et al, 2011), and recent evidence for copepods to modify their swimming behavior in response to exposure to hydrocarbon compounds (Seuront & Leterme, 2007;Seuront, 2010aSeuront, ,b, 2011a and 4-nonylphenol and nonylphenol-ethoxy-acetic-acid (Cailleaud et al, 2011), little is still known on the potential for chemical contaminants to affect copepod swimming behavior.…”