Long duration advertisement calls of nesting male plainfin midshipman fish are honest indicators of size and condition

The plainfin midshipman fish (Porichthys notatus) has long served as a model organism for neuroethology research on acoustic communication and related social behaviors. Type I or "singing" males produce highly stereotyped, periodic advertisement calls that are the longest known uninterrupted vertebrate vocalizations, lasting up to two hours in duration. Despite the extensive literature on the acoustic behaviour of this species, it remains unclear whether reproductive males signal their quality via their highly energetic, multiharmonic advertisement calls. Here, we recorded the advertisement calls of 22 reproductive type I males at night in a controlled laboratory setting in which males were housed in artificial tanks maintained at a constant temperature (13.9+0.3°C). The duration of the advertisement calls from type I males was observed to increase from the first call of the night to the middle call after which call duration remained steady until the early morning hours and first light. A strong positive correlation was observed between loudness (SPL and maximum SPL) of the advertisement call and body size (mass and standard length; rs>0.8). In addition, an asymptotic relationship was observed between the harmonic frequencies (F0-F10) of the advertisement calls and male body condition, with harmonic frequencies initially increasing with body condition but then plateauing at higher body condition. Taken together, our results suggest that type I male advertisement calls provide reliable honest information about male quality regarding size and body condition. Such condition dependent information of calling males could potentially be used by receptive females to help facilitate mate choice decisions.

Hurricane impacts on a coral reef soundscape

Soundscape ecology is an emerging field in both terrestrial and aquatic ecosystems, and provides a powerful approach for assessing habitat quality and the ecological response of sound-producing species to natural and anthropogenic perturbations. Little is known of how underwater soundscapes respond during and after severe episodic disturbances, such as hurricanes. This study addresses the impacts of Hurricane Irma on the coral reef soundscape at two spur-and-groove fore-reef sites within the Florida Keys USA, using passive acoustic data collected before and during the storm at Western Dry Rocks (WDR) and before, during and after the storm at Eastern Sambo (ESB). As the storm passed, the cumulative acoustic exposure near the seabed at these sites was comparable to a small vessel operating continuously overhead for 1–2 weeks. Before the storm, sound pressure levels (SPLs) showed a distinct pattern of low frequency diel variation and increased high frequency sound during crepuscular periods. The low frequency band was partitioned in two groups representative of soniferous reef fish, whereas the high frequency band represented snapping shrimp sound production. Daily daytime patterns in low-frequency sound production largely persisted in the weeks following the hurricane. Crepuscular sound production by snapping shrimp was maintained post-hurricane with only a small shift (~1.5dB) in the level of daytime vs nighttime sound production for this high frequency band. This study suggests that on short time scales, temporal patterns in the coral reef soundscape were relatively resilient to acoustic energy exposure during the storm, as well as changes in the benthic habitat and environmental conditions resulting from hurricane damage.

Sablefish (Anoplopoma fimbria) produce high frequency rasp sounds with frequency modulation

Sablefish sounds, named rasps, were recorded at two captive facilities in British Columbia and Washington State. Rasps consisted of highly variable broadband trains of 2 to 336 ticks that lasted between 74 and 10 500 ms. The 260 rasps that were measured contained frequencies between 344 and 34 000 Hz with an average peak frequency of 3409 Hz. The frequency structure of ticks within rasps was highly variable and included both positive and negative trends. This finding makes sablefish one of the few deep-sea fish for which sounds have been validated and described. The documentation of sablefish sounds will enable the use of passive acoustic monitoring methods in fisheries and ecological studies of this commercially important deep-sea fish.

Integrative taxonomy reveals a new species of Dollfusentis (Acanthocephala: Illiosentidae), in Orthopristis ruber (Osteichthyes: Haemulidae) from Rio de Janeiro, Brazil

The taxonomy of species of Dollfusentis is rather confused due to the overlap of morphological traits. The aim of this study was to follow an integrative taxonomy approach over the acanthocephalans collected from Orthopristis ruber in Brazil. Dollfusentis lenti n. sp. is described and is characterised by having an elongate trunk with spines sparsely distributed (largest 60-85 μm long) extending from the neck to almost reach the end of proboscis receptacle; additionally, the new species possesses a long proboscis with 12-14 longitudinal rows of 16-17 hooks each; 3-4 posterior hooks reduced in size, well-spaced from the eight ventrolateral crescent hooks, and lemnisci longer than proboscis receptacle. New sequences of 18S rDNA, ITS1, 5.8S and ITS2, 28S rDNA and COI mtDNA are provided. Dollfusentis bravoae is morphologically similar because it possesses the same number of proboscis hooks, although it differs by the size of testes and uterus and by having a higher number of trunk spines; additionally, new scanning electron micrographs and genetic data for both species support its distinction. Phylogenetic analysis obtained either with two nuclear genes or mitochondrial COI gene showed that Dollfusentis spp. belong to Illiosentidae, and the new species is yielded as the sister species of D. bravoae, with D. chandleri as the sister species of the latter two.

Intra- and Intersexual swim bladder dimorphisms in the plainfin midshipman fish (Porichthys notatus): Implications of swim bladder proximity to the inner ear for sound pressure detection

The plainfin midshipman fish, Porichthys notatus, is a nocturnal marine teleost that uses social acoustic signals for communication during the breeding season. Nesting type I males produce multiharmonic advertisement calls by contracting their swim bladder sonic muscles to attract females for courtship and spawning while subsequently attracting cuckholding type II males. Here, we report intra- and intersexual dimorphisms of the swim bladder in a vocal teleost fish and detail the swim bladder dimorphisms in the three sexual phenotypes (females, type I and II males) of plainfin midshipman fish. Micro-computerized tomography revealed that females and type II males have prominent, horn-like rostral swim bladder extensions that project toward the inner ear end organs (saccule, lagena, and utricle). The rostral swim bladder extensions were longer, and the distance between these swim bladder extensions and each inner-ear end organ type was significantly shorter in both females and type II males compared to that in type I males. Our results revealed that the normalized swim bladder length of females and type II males was longer than that in type I males while there was no difference in normalized swim bladder width among the three sexual phenotypes. We predict that these intrasexual and intersexual differences in swim bladder morphology among midshipman sexual phenotypes will afford greater sound pressure sensitivity and higher frequency detection in females and type II males and facilitate the detection and localization of conspecifics in shallow water environments, like those in which midshipman breed and nest.