Full Description

"The larger males, with elongated fins, are territorial and emit sounds during courtship. Smaller males, without elongated fins, act as sneakers. Both large and small males produce sounds in the presence of a ripe female. Males produce a grunt, lasting about 300 ms, made up of pulses repeated at a low rate (22–68 pps). Pulse duration, number, and repetition rate, did not differ between the two male types, but dominant frequency and sound amplitude did. Dominant frequency had a strong, inverse relationship with body size, whereas sound amplitude showed a weak positive relation to body size. Male size, and not the particular reproductive male tactic employed, is the most important correlate of sound properties in this species."

"The grass goby, Zosterisessor ophiocephalus, is a burrowing species, inhabiting the sea grassmeadows of shallow brackish waters along the coasts of Mediterranean and Black Sea. The breeding male of this species produces grunt-like sounds associated with territorial defence and courtship behaviour (Casaretto et al. 1988). The grunt emitted during fighting is often followed by a ‘staccato’ sound (Casaretto 1988)."

"The grass goby courtship sound is a grunt lasting, on average, 309 ms (range: 159–507 ms, n = 126). Grunts are produced either singly or, more commonly, in short sequences. Each grunt consists of a train of individual pulses repeated at a fairly regular rate (Figure 1a, b), the individual rate, however, varying from 21.8 to 68.3 pulses per second between males (n = 14). Each pulse is a damped oscillation lasting approximately 30 ms. The power spectrum of the whole sound peaks at 218 to 528 Hz (mean = 334 Hz, n = 126; Figure 1). Sound amplitude (SPL at about 5–10 cm from the emitter) varies from 63.1 to 88.1 dB. All the acoustic features (i.e. DUR, PN, PRR, FC, AMPL) differed significantly across males (p < 0.001 all tests). Individual mean values of PN, DUR and PRR did not differ between the group of males showing fin ray elongation and those lacking it (Table 1). By contrast, FC and AMPL differed significantly between the two groups of males, those without the trait producing sounds of higher peak frequency and lower amplitude (Table 1). FC was significantly and negatively correlated to TL, while AMPL was positively correlated with TL (Table 2). The relationships between dominant frequency and amplitude of the sound with body size are shown in Figure 2. Individual means of the FC and AMPL were not significantly correlated (rs = 0.256, p = 0.09), indicating that the relationship of these acoustic properties with fish body size was not due to a possible correlation between each other. Other sound properties (DUR, PN, PRR) did not show any significant relationship with body size (Table 2)."

"The results of the present study show that smaller grass goby males without fin ray elongation on the second dorsal fin are able to produce courtship sounds similar to those emitted by the larger males showing the trait."

"Sounds emitted by not-fin elongated males were weaker and higher pitched than those emitted by finelongated males (see Figure 1), but these differences were explained by male body size. The variability among individuals in the other acoustic properties (i.e. duration, number of pulses and pulse repetition rate) was unrelated to the male possessing the trait or to body size, but was most likely due to the different motivational/reproductive states of each individual male."

"It is worth ¨ noting that sound amplitude is remarkably low in this large size species, when compared, e.g., with the values of 120–150 dB (re 1 µPa)reported by Lugli& Torricelli (1999) for other small sized brackish gobies."

Observation Environment Quotes

"We caught fish from the Venice lagoon at the end of April 1999 with home-made nets of the type commonly used by local fishermen to catch this species. We sexed fish on the basis of the shape of the urogenital papilla (Miller 1984). We measured the total length, to the nearest mm, weighed total mass and held males isolated in outdoor experimental tanks (80 _ 40 _ 50 cm, 100 L) and females, in groups of 3–4 individuals, in laboratory tanks of the same size and shape of those used for males."

Behaviour Description Quotes

"The larger males, with elongated fins, are territorial and emit sounds during courtship. Smaller males, without elongated fins, act as sneakers. Both large and small males produce sounds in the presence of a ripe female."

Sound Name Quotes

"Males produce a grunt, lasting about 300 ms, made up of pulses repeated at a low rate (22–68 pps). Pulse duration, number, and repetition rate, did not differ between the two male types, but dominant frequency and sound amplitude did."