Two examples of fixed behavioural patterns in salmonines: female false spawning and male digging

Data collected from underwater video recordings in the wild and in a semi-natural channel were used to study two examples of relatively unknown behaviour in the Salmoninae subfamily—false spawning in females and digging in Oncorhynchus males. Observations suggest that false spawning should be regarded as an incomplete fixed behavioural pattern (FBP) and that male digging represents two special types of FBP (displacement FBP) with threatening and courting functions as ultimate causes.     

In-stream behaviour of threatened fishes and their food organisms based on remote video monitoring

Can remote underwater video be used to investigate the in-stream behaviour of small fishes and decapods? Diel activity of two threatened freshwater fishes (Macquaria australasica and Gadopsis bispinosus), a palaemonid prawn and an atyid shrimp, was established from remote underwater video in a pool of an upland stream in the current study. Decapods and large fishes (>5 cm TL) were nocturnal, whereas, small fishes (<5 cm TL) were diurnal. The suitability of using underwater video to quantify short-term (seconds) behavioural interaction among individuals was also demonstrated, with early-juvenile-phase Gadopsis bispinosus exhibiting interference competition on 35% of occasions when two or more individuals were observed. This study demonstrates that remote underwater video is useful for observing the in-stream behaviour of threatened freshwater fauna where other techniques are not viable, and presents sub-sampling of video as a means of reducing video processing time in assessing fish diel activity patterns.     

Visual accommodation and active pursuit of prey underwater in a plunge-diving bird: the Australasian gannet

Australasian gannets (Morus serrator), like many other seabird species, locate pelagic prey from the air and perform rapid plunge dives for their capture. Prey are captured underwater either in the momentum (M) phase of the dive while descending through the water column, or the wing flapping (WF) phase while moving, using the wings for propulsion. Detection of prey from the air is clearly visually guided, but it remains unknown whether plunge diving birds also use vision in the underwater phase of the dive. Here we address the question of whether gannets are capable of visually accommodating in the transition from aerial to aquatic vision, and analyse underwater video footage for evidence that gannets use vision in the aquatic phases of hunting. Photokeratometry and infrared video photorefraction revealed that, immediately upon submergence of the head, gannet eyes accommodate and overcome the loss of greater than 45 D (dioptres) of corneal refractive power which occurs in the transition between air and water. Analyses of underwater video showed the highest prey capture rates during WF phase when gannets actively pursue individual fish, a behaviour that very likely involves visual guidance, following the transition after the plunge dive's M phase. This is to our knowledge the first demonstration of the capacity for visual accommodation underwater in a plunge diving bird while capturing submerged prey detected from the air.     

Ocean-bottom krill sex

For the first time the entire sequence of the mating behaviour of Antarctic krill (Euphausia superba) in the wild is captured on underwater video. This footage also provides evidence that mating can take place near the seafloor at depths of 400-700 m. This observation challenges the generally accepted concept of the pelagic lifestyle of krill. The mating behaviour observed most closely resembles the mating behaviour reported for a decapod shrimp (Penaeus). The implications of the new observation are also discussed.     

Classifying and inferring behaviors using real‐time acceleration biotelemetry in reproductive steelhead trout (Oncorhynchus mykiss)

Movement behaviors are central to ecology and conservation. Movement sensing technologies can monitor behaviors that are otherwise difficult to observe under field conditions and may enhance the ability to quantify behaviors at the population scale. We monitored steelhead trout (Oncorhynchus mykiss) spawning behaviors in a seminatural enclosure using accelerometer telemetry tags while simultaneously observing behaviors with underwater cameras. Behavioral assignments from visual observations were compared to acceleration histories to develop assignment criteria for acceleration data, including for a key behavior (oviposition). Behavioral events independently classified using acceleration data prior to reviewing video were compared to video scoring and 97% of holding behaviors, 93% of digging behaviors, and 86% of oviposition/covering behaviors were correctly assigned using acceleration data alone. We applied the method to at‐liberty steelhead in spawning tributaries. Acceleration records revealed putative spawning and oviposition in at‐liberty female steelhead, and time budgets for at‐liberty steelhead were similar to those monitored within enclosures. The use of similar movement sensing tags and classification approaches offers a method for monitoring movement behavior, activity budgets, and habitat use in a broad array of aquatic and terrestrial taxa, and may be especially useful when behaviors are cryptic.     

Territorial and non-territorial spawning behaviour in the bream

The spawning behaviour of bream Abramis brama was studied in 1993, in a harbour on the River Meuse, Belgium. Fish spawned from 22 to 27 April and from 11 to 14 May, when the water temperature rose to 14.5) C. The reproductive behaviour of the bream was studied within a 15 m long part of the harbour using a video camera. Territorial males with tubercles (33–43 cm total length; >5 years old) defended bank areas of diameter 80–150 cm which included spawning substratum, i.e. roots of alder and willow trees and aquatic plants. Water depth ranged from 25 to 50 cm. Non-territorial males without tubercles (24–33 cm; 3–4 years old), remained 2–4 m away from the bank. Aggressive behaviour between males was frequent and, occasionally, males with tubercles were unable to defend a territory. Mature females (25–43 cm; >3 years old), coming from the deeper water of the surrounding area, were followed by non-territorial males before spawning in territories near the bank.     

Behaviour of temperate and sub-tropical reef fishes towards a stationary SCUBA diver

Using remote underwater stereo–video systems we examined fish behaviour towards a stationary SCUBA diver at temperate (Rottnest Island) and sub-tropical (Houtman Abrolhos Islands) reefs in Western Australia. Changes in species richness, relative abundance, fish length, and the mean distance of individual fish from stereo–video cameras, in the presence and absence of a SCUBA diver, were assessed to infer changes in behaviour. Results show that a stationary SCUBA diver may obtain accurate measures of species richness and of the composition of fish assemblages in an area. However, the usefulness of these measures to reflect changes in fish behaviour appears limited as responses of fish towards the stationary SCUBA diver were highly species specific. Several species differed in their mean relative abundance (Heterodontus portusjacksoni, Coris auricularis, Thalassoma lunare), length (Ophthalmolepsis lineolatus, C. auricularis), and the distance to which they would approach the stereo–video systems (Kyphosus sydneyanus, Scarus schlegeli) when a SCUBA diver was present. Here, species-specific changes in the behaviour of several common and abundant fish species towards a stationary SCUBA diver advises caution to avoid biases when interpreting results obtained by SCUBA divers.     

Play it again: the use of video records in behavioural studies with small cetaceans

Some difficulties arise in studying the behaviour of marine mammals at their natural habitat mainly because they spend most of their time underwater and have complex behaviours. Therefore, many protocols and sample methods are available to better assess the behavioural ecology of this animals. Here, we compared two behavioural recording methods. The first one was the direct visual observation. The second one was recording using a digital video recorder. We hypothesise that the possibility of watching recorded videos repeatedly leads to a higher quantification of behaviours compared with the direct observation method. We found a slight variation in the frequency of behaviours according to the method used. Furthermore, we found that the video recordings should not be used as a replacement for the direct observation method. Finally, we highlighted the strengths and weaknesses of both methods. We recommend that in behavioural research, the use of video recording should be careful; it is preferable that an experienced researcher uses the direct observation method, while it is best for a person with low know–how to the use the video recording method.     

A quantitative analysis of underwater oviposition by the mosquito Mansonia titillans

ABSTRACT. Formation of the rosette-like egg mass of the neotropical mosquito Mansonia titillans Walker is described from video recordings of thirteen females ovipositing on the undersurfaces of water lettuce ( Pistia stratiotes ) leaves in the laboratory. The female abdomen executes symmetrical stroking behaviour to the right and left of centre line. Outstrokes consist solely of scratching, in which spines on the eighth tergite abrade the leaf surface preparatory to oviposition. A row of eggs is glued to the leaf only on instrokes, which are of longer duration than outstrokes, and may be interrupted by scratches and pauses. Scratching precedes oviposition of each of the first four eggs, which are laid without stroking behaviour. The egg mass is enveloped in an air bubble which is transported underwater on the hydrofuge female abdomen. The deposition of eggs on instrokes is homologous to the behaviour used by Culex and Culiseta mosquitoes in the construction of free-floating egg rafts.     

Comparison of remote video and diver's direct observations to quantify reef fishes feeding on benthos in coral and rocky reefs

This study compared remote underwater video and traditional direct diver observations to assess reef fish feeding impact on benthos across multiple functional groups within different trophic categories (e.g. herbivores, zoobenthivores and omnivores) and in two distinct reef systems: a subtropical rocky reef and a tropical coral reef. The two techniques were roughly equivalent, both detecting the species with higher feeding impact and recording similar bite rates, suggesting that reef fish feeding behaviour at the study areas are not strongly affected by the diver's presence.     

Looking for love under the ice: Using passive acoustics to detect burbot (Lota lota: Gadidae) spawning activity

1. Burbot (Lota lota: Gadidae) is a difficult species to manage effectively due to its preference for deep-water habitats and under-ice spawning behaviour, resulting in a poor understanding of its reproductive activity. However, the use of acoustic signalling by burbot as part of their mating system has recently been described and this behaviour may provide a means of investigating questions regarding the spatial and temporal distribution of spawning aggregations using passive acoustic monitoring.
2. We used audio and video recording to confirm that burbot vocalise and that these vocalisations can be detected under field conditions as well as to characterise the relationship between burbot acoustic signalling and spawning behaviour. We also evaluated the feasibility of locating and monitoring burbot spawning aggregations in real time using passive acoustics.
3. Burbot vocalisations were difficult to identify with only about 6% of the recordings containing calls being successfully identified as such in the field. Burbot vocalised more often between sundown and sunrise than during daylight hours. Calls recorded at night tended to be lower frequency, longer duration, and have lower bandwidth than those made during the day.
4. Burbot vocalisations could not be recorded in conjunction with video recordings of spawning activity, indicating that burbot may not call during active spawning, but may use acoustic communication to signal the onset of reproductive readiness and to form pre-spawning aggregations.
5. While burbot calls were readily identifiable, observers had a difficult time identifying burbot calls in real time under field conditions. Passive acoustic monitoring demonstrates considerable potential as a management tool to locate burbot spawning grounds and identify periods of activity, but may not be an appropriate technique for monitoring spawning activity in real time.

     

Grayling (Thymallinae) phylogeny within salmonids: complete mitochondrial DNA sequences of Thymallus arcticus and Thymallus thymallus

The phylogenetic relationships among the three subfamilies (Salmoninae, Coregoninae and Thymallinae) in the Salmonidae have not been addressed extensively at the molecular level. In this study, the whole mitochondrial genomes of two Thymallinae species, Thymallus arcticus and Thymallus thymallus were sequenced, and the published mitochondrial genome sequences of other salmonids were used for Bayesian and maximum‐likelihood phylogenetic analyses. These results support an ancestral Coregoninae, branching within the Salmonidae, with Thymallinae as the sister group to Salmoninae.     

Evidence supporting the paraphyly of Hucho (Salmonidae) based on ribosomal DNA restriction maps

Relationships among the less derived genera in the subfamily Salmoninae were investigated by phylogenetic analysis of data from restriction maps of the ribosomal DNA using Osmerus mordax (rainbow smelt), Coregonus hoyi (bloater), and Thymattus arcticus (Arctic grayling) as outgroups. Analysis of the results suggests that Hucho h. taimen is more closely related to Brachymystax lenok (lenok) than to Hucho perryi (Sakhalin taimen) and that B. lenok and Hucho h. taimen (Eurasian taimen) form the most ancestral clade of the Salmoninae.     

Mystery pufferfish create elaborate circular nests at mesophotic depths in Australia

In 2011, the enigma of “mystery circles,” small but complex underwater structures first observed by divers from southern Japan in 1995, was solved when a new species of pufferfish, white-spotted pufferfish (Torquigener albomaculosus Matsuura 2014), was identified as the responsible agent. To date these circles have been described only from Japan, where they are formed on a sandy seafloor in water depths less than 30 m. A survey of oil field infrastructure on the North West Shelf of Western Australia in 2018 using a remotely operated vehicle and hybrid autonomous underwater vehicle (HAUV) recorded a high-resolution video and bathymetric data of 21 circular formations with similar features to those described in Japan. The circles display dimensions and morphology like those described from Japan, but were observed in water depths between 129 and 137 m. The HAUV also recorded high-resolution photographs which captured a Torquigener sp. fish in the immediate vicinity of the circles. An additional circle and Torquigener sp. were observed in images collected by baited remote underwater stereo-video in a nearby location in 129 m depth. These circles are the first to be found in Australia. The pufferfish species responsible cannot be identified from images collected. Such a discovery not only generates intrigue and wonder among scientists and the general public but also provides an insight into the reproductive behaviour and evolution of pufferfish globally.     

The effect of motorboat sound on Australian snapper Pagrus auratus inside and outside a marine reserve

Human‐generated sound affects hearing, movement, and communication in both aquatic and terrestrial animals, but direct natural underwater behavioral observations are lacking. Baited underwater video (BUV) were deployed in near shore waters adjacent to Goat Island in the Cape Rodney–Okakari Point Marine Reserve (protected) or outside the reserve approximately four km south in Mathesons Bay (open), New Zealand to determine the natural behavior of Australian snapper Pagrus auratus exposed to motorboat sound. BUVs worked effectively at bringing fish into video range to assess the effects of sound. The snapper inhabiting the protected area showed no behavioral response to motorboat transits; however, fish in the open zones either scattered from the video frame or decreased feeding activity during boat presence. Our study suggests that motorboat sound, a common source of anthropogenic activity in the marine environment can affect fish behavior differently depending on the status of their habitat (protected versus open).     

Testing an Adaptive Hypothesis Through Context-Dependence: Effects of Water Depth on Foraging Behaviour in Three Species of Garter Snakes

Adaptive hypotheses based on interspecific comparisons can be tested by evaluating the context‐dependence of the behaviour of individual organisms. Drummond (Behaviour, 86, 1983, 1) categorized garter snake species (Thamnophis) as terrestrial–aquatic generalists or aquatic specialists based on diet and aquatic foraging behaviour. He hypothesized that the characteristic foraging behaviours of aquatic specialists – including frequent crawling on the underwater substrate and a high rate of underwater predatory strikes – are adaptations for feeding on relatively widely dispersed aquatic prey. Drummond's hypothesis based on interspecific comparisons suggests that individual snakes might change their foraging in the direction of aquatic specialist behaviour with an increase in water depth (which increases prey dispersion). I tested this prediction through laboratory observations of Mexican Pacific lowlands garter snakes (T. validus) feeding on minnows in shallow (2 cm) and deep (3–7 cm) water. Members of this species are appropriate subjects because they are ecologically intermediate between the generalists and aquatic specialists studied by Drummond, and thus might be expected to show more variation in aquatic foraging behaviour than those species. T. validus showed significantly higher frequencies of crawling on the underwater substrate and of underwater strikes in the deep water than in the shallow water; i.e. increased water depth shifted the behaviour of these snakes toward that of aquatic specialists, thus supporting Drummond's hypothesis. Individuals of an aquatic specialist species, the narrow‐headed garter snake (T. rufipunctatus), showed less pronounced changes in behaviour with increased water depth. Western ribbon snakes (T. proximus), which feed primarily at the land–water interface (and are expected to act like terrestrial–aquatic generalists), typically refused to feed in deep water. Interspecific differences in underwater visual acuity may underly the behavioural differences among the three species by determining whether changes in foraging behaviour with water depth are advantageous. Information on phylogenetic relationships suggests that the facultative behaviour of T. validus may represent an intermediate stage in the evolution of aquatic specialization.     

Lake trout (<Emphasis Type="Italic">Salvelinus namaycush</Emphasis>) spawning behaviour: the evolution of a new female strategy

A video camera inside an underwater housing was used to record the spawning activities of lake trout, Salvelinus namaycush, in Kushog Lake, Ontario (Canada). Contrary to the commonly accepted belief describing lake trout as the only salmonine to spawn exclusively at night, the recordings were taken during the day. Lake trout spawning behaviour is described in detail and compared with other salmonine species. The loss of female “nest-building” and assumption of a novel itinerant strategy during which females travel across the breeding grounds accompanied by a group of males, is considered to be an important change in the evolution of the lake trout’s unique mode of spawning.     

Field-based Behavioural Bioassays for Testing the Efficacy of Antifouling Coatings

Improving non-toxic coatings using immersion trials is time consuming and requires more rigorous data analysis than is necessary for toxic coatings. The aim of this study was to determine if the exploratory behaviour of barnacle cyprids on coatings deployed in the field can be used as a bioassay for coating efficacy. A standard tin-based coating, and a silicone and unknown non-toxic coatings were videoed remotely underwater using a high resolution camera. Exploratory behaviours of the coatings by cyprids were digitised. There was a significant difference in larval behaviour between coatings (MANOVA, p <0.001 ). Canonical discriminant analysis clearly separated the three coatings and enabled 100% prediction of group membership. Thus the behaviour of exploring cyprids can be used to discriminate between the coatings. This study has demonstrated how a simple field-based bioassay could be suitable for the testing of antifouling coatings and may therefore offer some scope for rapidly pre-screening coatings prior to full-scale immersion trials. However, several disadvantages with the bioassay are noted, including variable illumination in the field, the high cost of the equipment used, the long time required to manually analyse recorded video, and the need for a predictable larval supply.