Ovalipes Catharus Research Articles

High densities of large tuaki, the New Zealand cockle Austrovenus stutchburyi, provide a post-settlement predation refuge for conspecific juveniles

Bivalves are ecosystem engineers, and their effective management relies on a full understanding of the mechanisms that influence population dynamics. Juvenile tuaki (New Zealand cockle) Austrovenus stutchburyi, a numerically dominant and ecologically important bivalve in New Zealand estuaries, were found at higher densities when surrounded by high densities of large adults within Waitati Inlet, in southern New Zealand. Consequently, we hypothesised that adults provided a refuge from predation for juveniles, resulting in higher juvenile survival and retention in dense beds. The observed pattern was consistent with post-settlement Allee effects, where declines in density and truncated size distributions may have resulted in unsuccessful recruitment if a density threshold was reached. Field experiments were undertaken in 2020 and 2021 to test the potential sheltering effect of adults on retention and survival of juveniles, with and without the addition of organic loading of sediments. Presence of adults had significant effects on juvenile retention and interaction with organic loading in 2020, but not in 2021. To isolate the effects of adult presence on predation of juveniles, a series of laboratory experiments were carried out using the predatory crab Ovalipes catharus. Juvenile survivorship from crab predation was enhanced in the presence of large adults, consistent with the hypothesised sheltering effect. Further, predation rates increased significantly from winter to summer, which correlated with increasing water temperatures and the breeding and moult cycle of crabs. These findings across surveys, field and laboratory manipulations have significant implications for effective fisheries management and restoration of bed-forming bivalves.

Impact of small boat sound on the listening space of Pempheris adspersa, Forsterygion lapillum, Alpheus richardsoni and Ovalipes catharus

Anthropogenic stressors, such as plastics and fishing, are putting coastal habitats under immense pressure. However, sound pollution from small boats has received little attention given the importance of sound in the various life history strategies of many marine animals. By combining passive acoustic monitoring, propagation modelling, and hearing threshold data, the impact of small-boat sound on the listening spaces of four coastal species was determined. Listening space reductions (LSR) were greater for fishes compared to crustaceans, for which LSR varied by day and night, due to their greater hearing abilities. Listening space also varied by sound modality for the two fish species, highlighting the importance of considering both sound pressure and particle motion. The theoretical results demonstrate that boat sound hinders the ability of fishes to perceive acoustic cues, advocating for future field-based research on acoustic cues, and highlighting the need for effective mitigation and management of small-boat sound within coastal areas worldwide.

Comparative sound detection abilities of four decapod crustaceans

Sound perception and detection in decapod crustaceans is surprisingly poorly understood, even though there is mounting evidence for sound playing a critical role in many life history strategies. The suspected primary organ of sound perception is the paired statocysts at the base of the first antennal segment. To better understand the comparative sound detection of decapods, auditory evoked potentials were recorded from the statocyst nerve region of four species (Leptograpsus variegate, Plagusia chabrus, Ovalipes catharus, Austrohelice crassa) in response to two different auditory stimuli presentation methods, shaker table (particle acceleration) and underwater speaker (particle acceleration and pressure). The results showed that there was significant variation in the sound detection abilities between all four species. However, exposure to the speaker stimuli increased all four species sound detection abilities, in terms of both frequency bandwidth and sensitivity, compared with shaker table-derived sound detection abilities. This indicates that there is another sensory mechanism in play as well as the statocyst system. Overall, the present research provides comparative evidence of sound detection in decapods and indicates underwater sound detection in this animal group was even more complex than previously thought.

Sound production and associated behaviours in the New Zealand paddle crab Ovalipes catharus

Despite growing evidence that crustaceans produce and detect sounds, the behavioural and biological function of these sounds is still poorly understood. Here, we describe sounds produced by the New Zealand paddle crab, Ovalipes catharus, and provide evidence of intraspecific communication using underwater sound. Acoustic and video analyses of tank-based experiments show that O. catharus produce at least three distinct sounds: the rasp, zip and bass. Notably, two of these sounds, the zip and bass, were directly correlated with post-copulatory mate-guarding and courtship behaviour and produced only by competing adult male crabs in the presence of a receptive female. Rasp sounds were produced by both sexes; the occurrence significantly increased in the presence of food, and play-back experiments of these sounds initiated a foraging-like behaviour. Responses to rasps might have evolved as a result of acoustic spying. Further, we show that both the rasp and bass sounds were produced by an alternative mechanism than stridulation of the chela ridges. This refutes widespread assumptions that Ovalipes crabs use only stridulation of ridges along their chelae to produce rasp-like sounds. Our results suggest that sound production in decapod crustaceans may be more widespread than previously presumed.

Early stages of a New Zealand invasion by Charybdis japonica (A. Milne-Edwards, 1861) (Brachyura: Portunidae) from Asia: behavioral interactions with a native crab species

The Asian paddle crab, Charybdis japonica (A. Milne-Edwards, 1861), is a relatively recent invader (approx. 10 years) to northeastern New Zealand, and its large size and aggressive nature makes it a potentially formidable competitor with native species. The only endemic, similarly sized, New Zealand paddle crab, Ovalipes catharus (White and Doubleday, 1843), overlaps frequently with C. japonica in both habitat and diet. To understand their probable interactions in the field, we performed a series of experimental behavioral trials in a closed laboratory system to determine whether the crabs interact antagonistically over a shared prey resource (Perna canaliculus (Gmelin, 1791) – green-lipped mussel). In interspecific trials, C. japonica frequently displaced both sexes of O. catharus from the prey, while O. catharus usually failed to acquire prey from feeding C. japonica. In addition, male C. japonica dominated both male and female O. catharus in one-on-one competition for food, regardless of which crab possessed the food initially. Overall, male C. japonica behaved aggressively towards O. catharus and conspecifics of equal size when competing for a prey item; O. catharus showed low levels of aggression throughout all trials and increased time spent evading C. japonica as compared to C. japonica’s high levels of aggression. Our research highlights the importance of understanding how aggressive behavior may influence establishment success of invading species.

Thermal limits of portunid crab heart mitochondria: Could more thermo-stable mitochondria advantage invasive species?

The distributions of the native crab Ovalipes catharus and the invasive species Charybdis japonica within New Zealand shores may be defined by thermal tolerance. Doppler ultrasound showed that with increasing temperature O. catharus and C. japonica raised their heart rates ( p ≤ 0.05). However, C. japonica showed greater plasticity in heart beat duration, or contraction rate with increasing temperature, while O. catharus was more inclined to increase heart rate, and already had a shorter more rapid contraction at 19 °C. Saponin permeabilized heart fibres enabled tests of mitochondrial function in situ and showed that Leak-I respirational flux was highest for O. catharus at all temperatures. C. japonica showed a greater inner mitochondrial membrane integrity which suggests tighter coupling of oxidative phosphorylation. Although Complex I lost function on exposure to 30 °C in both species, this occurred more rapidly in O. catharus. Complex II function remains stable at high temperature in both species. O. catharus had higher cytochrome c oxidase (CCO) flux at all temperatures compared to C. japonica indicating elevated concentrations of CCO in O. catharus. The scope to increase CCO flux was greater in the more stenothermal O. catharus than in C. japonica. Overall, this study shows substantial differences in heart function and mitochondria between crab species and provides evidence that mitochondrial integrity may limit species survival and potentially future distributions.

Uptake of paralytic shellfish poisoning and spirolide toxins by paddle crabs ( Ovalipes catharus) via a bivalve vector

The uptake of paralytic shellfish poisoning (PSP) toxins and spirolides by the paddle crab ( Ovalipes catharus) was investigated in two laboratory feeding trials using Greenshell™ mussels ( Perna canaliculus), which had been fed toxic strains of either Alexandrium catenella or A. ostenfeldii, as a vector. Toxin uptake by crabs occurred in both feeding trials and was limited to the visceral tissue; no toxins were detected in the body meat or the gills. The first trial utilized a strain of A. catenella that had high total PSP toxin content, 442.3 ± 91.6 fmol/cell, that was dominated by low toxicity N-sulfocarbamoyl toxins resulting in a low cellular toxicity, 5.5 ± 1.6 pg STXequiv./cell. In this trial, toxin accumulation in the crabs was highly variable and ranged from 3.8 to 221.5 μg STXequiv./100 g, with 3/4 of the crabs exceeding the regulatory limit of 80 μg STXequiv./100 g. Eight days after feeding on toxic mussels the crabs still retained high levels of toxin suggesting that depuration rates in this species may be slow. In the second feeding trial, the A. ostenfeldii strain fed to mussels produced low levels of both PSP toxins (52.0 ± 19.5 fmol/cell; 1.4 ± 0.3 pg STXequiv./cell) and spirolides (1.8 pg/cell) and, as a result, the concentration transferred to crabs via the mussels was very low-PSP toxins ranged from 2.5 to 6.8 μg STXequiv./100 g and spirolides from 6 to 7 μg/kg. The results of our study demonstrate that paddle crabs are capable of acquiring both PSP toxins and spirolides and suggest that this may occur in the wild during a toxic shellfish event. It also highlights the need to remove the viscera before consumption.

Comparison of the ectosymbionts and parasites of an introduced crab, Charybdis japonica, with sympatric and allopatric populations of a native New Zealand crab, Ovalipes catharus (Brachyura: Portunidae)

The success of biological invaders is often attributed to escape from specialist enemies in their natural range, such as predators and parasites. For enemy escape to have direct consequences in competitive interactions, invaders need to be less vulnerable to enemies than native competitors in the region they invade, but first the presence of these enemies must be established. We investigated the macroparasite and ectosymbiont fauna of the recently introduced portunid crab Charybdis japonica, and compared it with sympatric and allopatric populations of the native New Zealand portunid, Ovalipes catharus. A total of 468 crabs (350 O. catharus and 118 C. japonica) were collected from six harbours throughout New Zealand (Whangarei, Waitemata, Nelson, Lyttelton, Dunedin, and Bluff) and the identity, incidence and prevalence of ectosymbionts and parasites were compared among the different populations. Charybdis japonica and O. catharus harboured different ectosymbionts. Serpulid polychaete tubes occurred on the exoskeleton of 85.4% of C. japonica examined, but were absent from O. catharus. The bryozoan, Triticella capsularis occurred on 97.4% of O. catharus but was not found on C. japonica. Few endoparasites were present in either species. An unidentified juvenile ascaridoid nematode occurred in the hindgut of 5.9% of C. japonica, but was not found in sympatric populations of O. catharus. A second, unidentified species of ascaridoid nematode occurred in 7.1% of O. catharus from Nelson, but was not present in specimens from the five other harbours sampled. Melanised lesions were observed in the muscle tissue of almost half (46.6%) of the C. japonica examined. Histological examination showed these to be of two types: (1) spherical bodies resembling melanised trematode metacercariae; and (2) lesions consistent with wound repair. Lesions were not observed in O. catharus. Although the identity of parasites and epibionts carried by each species differed, both C. japonica and O. catharus had relatively low parasite species richness. We could not test whether the introduced portunid, C. japonica, is any less vulnerable to parasite enemies than the New Zealand portunid, O. catharus.

Adaptive Multi-scale Sampling to Determine an Invasive Crab’s Habitat Usage and Range in New Zealand

Patterns of local abundance and geographical distribution are often prime correlates of invasive species’ impacts on native ecosystems. Here we adaptively increased the spatial scale of delimitation surveys to determine the local abundance, range and habitat associations of the introduced portunid Charybdis japonica (Milne-Edwards, 1861) in New Zealand. The crab was first discovered in Auckland’s Waitemata Harbour in September 2000, and by April 2002 trapping surveys revealed the invader had spread widely throughout the Harbour. Experiments using three deployment times (1, 3 and 24 h) optimized detection rates prior to larger scale geographic surveys that defined the range of the introduced population. We surveyed >300 sites in coastal waters within the predicted range of larval dispersal and then 14 major shipping ports throughout New Zealand. C. japonica was abundant in the Waitemata Harbour and present in two nearby estuaries, but there was no evidence of spread to other shipping ports nationwide. Subtidal habitat associations were explored in the main area of infestation which indicated that the invader occupied a range of substrata from fine, silty muds to coarse, shelly sands. Although its distribution overlaps with the native portunid crab Ovalipes catharus, the invader was more abundant throughout Waitemata Harbour and occurred in muddy sediments where native portunids are rare. It is not yet clear whether the C. japonica population in New Zealand is self-sustaining, however if it persists and continues to spread, it is likely to have significant impacts on native estuarine benthic assemblages.

A new ctenostome bryozoan ectosymbiotic with terminal‐moult paddle crabs (Portunidae) in New Zealand

Triticella capsularis sp. nov. (Bryozoa, Ctenostomata) is newly described as an ectosymbiont of paddle crabs (Ovalipes catharus) in central New Zealand (Bay of Plenty to northern South Island). The bryozoan produces the longest zooids known in the genus Triticella, with colonies forming a “fur” up to almost 10 mm thick on large crabs, mostly males. The densest area of colonisation is the ventral anterior half of the crab. The bryozoan lives only on O. catharus and probably benefits from its “messy” and voracious feeding habits, opportunities for gene exchange during crab swarming behaviour, and dispersal. There is no synchrony between reproduction of the bryozoan and moulting cycles of the crab, as the bryozoan achieves reproductive colony size only on old terminal‐moult crabs. Although visually striking when dense, the bryozoan growth is only superficial and affects neither the behaviour of the crab nor the quality of its meat.

Avoidance of post-coital cannibalism in the brachyurid paddle crab Ovalipes catharus

Sexual cannibalism was examined experimentally in the New Zealand paddle crab Ovalipes catharus, where it is the female that risks cannibalism during and after sexual activity. In this species copulation only occurs when the female is soft-shelled after moulting and she is most vulnerable to cannibalism. Male paddle crabs protect and copulate with the females until the females are no longer sexually receptive. Males appear able to identify a female with whom they have recently copulated. After a brief separation, significantly fewer females were cannibalized in cases where a female was returned to her original sexual partner than in those that had exchanged partners. The asymmetry, where females gain some protection during moulting but males receive no such advantage, may, at least partially, explain the skewed sex ratios which are sometimes found in samples of O. catharus from nature.

VENTILATORY AND VASCULAR ROUTES IN A SAND-BURYING SWIMMING CRAB, OVALIPES CATHARUS (WHITE, 1843) (BRACHYURA: PORTUNIDAE)

A B S T R A C T Ovalipes catharus is a burrowing portunid which utilizes both forward and reverse ventilation. The proportions of time spent in each ventilatory mode depend upon burial state and activity. In forward ventilation, water enters the hypobranchial space of the branchial chambers at the bases of the legs, flows between the gill lamellae to the epibranchial space, and is exhaled anteriorly via the prebranchial apertures lateral to the mouthparts. This flow is countercurrent to the general hemolymph flow in the gills. In reverse-ventilating crabs, water enters anteriorly into the epibranchial space. Most of this water does not ventilate the lamellae, but passes between the epibranchial surfaces of the gills and the branchiostegites to be exhaled posteriorly between the fourth and fifth pereiopods. A variable (usually minor) fraction of the water exits from the Milne Edwards apertures, presumably taking a concurrent, epibranchial to hypobranchial, route. The arterial and venous circulations are described from vascular casts. From these the potential for the branchiostegal circulation to function as an alternative site for respiratory gas exchange was examined. Each branchiostegite is extensively vascularized with a sheet of interconnecting sinuses and lacunae. Hemolymph enters anteriorly from the hepatic sinuses and is returned to the pericardium laterally and posteriorly, thus forming a vascular shunt parallel to the branchial circulation. It is unclear whether the branchiostegite is important in gas exchange in this crab. Vascular casts of a number of other significant structures, including the heart, cor frontale, and antennal glands are described.

Seasonal incidence of egg‐bearing in the New Zealand paddle crabOvalipes catharus(Crustacea: Brachyura), and its production of multiple egg batches

Abstract The annual reproductive cycle of Ovalipes catharus (White) was investigated by determining the proportion of mature females carrying eggs, in samples of crabs taken at dusk every 4 or 5 weeks for 22 months from Plimmerton Beach, near Wellington, New Zealand. Three peaks of egg‐bearing were found over each breeding season: the first during August, the second through late November and early December, and the last during early January into early April. The average carapace width (CW) of crabs carrying eggs was 84.6 ± 9.65 mm and this average did not alter significantly during the year. Smaller female crabs (41–60 mm CW) were found carrying eggs predominantly during January and February. Captive O. catharus were able to produce a maximum of five batches of eggs during one intermoult period, from a single insemination. The average number of egg batches produced increased with crab size. Crabs 90 mm CW produced an average of three ...

Reproduction in the paddle crabOvalipes catharus(Decapoda: Portunidae) from Blueskin Bay, Otago, New Zealand

Abstract Reproduction was investigated in the paddle crab (Ovalipes catharus) in Blueskin Bay, Otago, from March 1984 to April 1985. From oocyte size‐frequency analysis it appeared that one clutch of oocytes was developed and spawned completely. No evidence of multiple spawning using sperm from a single copulation was found. Seasonal ovarian development and the presence of ovigerous females showed that spawning occurred from September to February inclusive. However, few ovigerous females were caught during sampling. No spermatogenic cycles were observed in males and they appeared to be able to copulate at any time. Size at first sexual maturity was estimated on the basis of gonadal condition and relative growth to occur at a carapace width of 55–65 mm. O. catharus from Wellington and Canterbury were estimated to mature at a smaller size than those in Blueskin Bay. This difference may be caused by decreasing water temperature associated with increasing latitude.

Size Relationships and Relative Growth of the New Zealand Swimming Crab Ovalipes catharus (White, 1843)

Size Relationships and Relative Growth of the New Zealand Swimming Crab Ovalipes catharus (White, 1843)

Biology of feeding in the New Zealand paddle crabOvalipes catharus(Crustacea, Portunidae)

Abstract No significant differences in appetite (used here in the sense of amount of food consumed over any given 24‐hour period) were found between crabs starved for 28 days and crabs freshly caught from the sea when fed to satiation over a 13‐day period. Crabs from these two feeding history treatments also exhibited the same level and rate of appetite depression. Longer periods of feeding depressed appetite still further. Although feeding may only minimally influence appetite over any two‐ or three‐day time span, feeding to satiation over 13 consecutive days significantly depressed appetite. Experiments, using the predatory crab Ovalipes catharus, tested the effectiveness of starvation for standardising appetite. Individual appetites were highly variable and were not standardised by up to 21 days starvation. At temperatures above 15 °C, Paphies subtriangulata and Callianassa filholi were either cleared from the foregut or were unrecognisable within 6 hours. However, at about 10 °C, these prey could take...

Depth and density of burial by the bivalve Paphies ventricosa as refuges from predation by the crab Ovalipes catharus

In experimental conditions, the level of predation by the paddle crabs Ovalipes catharus (White, 1843) on the intertidal bivalve Paphies ventricosa (Gray, 1843) of 30 to 40 mm shell length, was investigated as a function of depth and density of bivalve burial. Bivalves and crabs were collected from the west coast of New Zealand between November 1984 and February 1985. The predation level declined in a linear fashion with increasing depth: the number of P. ventricosa eaten was 70.67–1.33x(depth available for burial in cm), between 0 and 26 cm depth. At three bivalve densities, 500, 1 253, and 2 000 m-2, while the actual numbers eaten from each density were equal, the proportion eaten declined in a non-linear fashion with increasing density. The density of P. ventricosa had, in effect, a negative density-dependent influence on the level of predation by O. catharus. Therefore, both depth and density can act as refuges from predation.

Natural diet of the crab Ovalipes catharus (Crustacea, Portunidae) around central and northern New Zealand

Foregut contents were exam~ned of 4324 OvaLipes catharus (White 1843) collected from 11 locations in central and northern New Zealand, from November 1984 to September 1985. Of these 2572 foreguts contained recognizable food items, and a total of 72 species were identified in the diet. No significant differences were found in the relative proport~ons of foregut contents between males and females. Sand was an important component of the foregut contents, but was not considered part of the diet. When measured in terms of frequency of occurrence and eshmated volumes (points method), Mollusca dominated the diet at 6 locations and Crustacca at 5. At all locahties almost all the Mollusca eaten were small juvenile bivalves, mainly from the commercially and recreationally important genus Paphies. Callianassa filholi, 0. catharus, ~sopods, and amphipods were ~mportant Crustacea in the diet at different localities. The diet at all localities differed significantly in the proportions of 14 dietary categories, but when 6 generalized dietary categories werr considered similarities were found. 0. catharus is a versatile and opportunistic predator. Thc possible impact of t h ~ s predator on commercially important shellfish species is discussed.

87:6515 Size relationships and relative growth of the New Zealand swimming crab Ovalipes catharus (White, 1843) : Davidson, R.J. and I.D. Marsden, 1987. J. crustacean Biol., 7(2):308–317. Zool. Dept., Univ. of Canterbury, Private Bay, Christchurch 1, New Zealand

87:6515 Size relationships and relative growth of the New Zealand swimming crab Ovalipes catharus (White, 1843) : Davidson, R.J. and I.D. Marsden, 1987. J. crustacean Biol., 7(2):308–317. Zool. Dept., Univ. of Canterbury, Private Bay, Christchurch 1, New Zealand

SIZE RELATIONSHIPS AND RELATIVE GROWTH OF THE NEW ZEALAND SWIMMING CRAB OVALIPES CATHARUS (WHITE, 1843)

Relative growth of the swimming crab Ovalipes catharus was described from measurements made on the carapace, abdomen, gonopod, and chelipeds using carapace width (cw) as the reference dimension. Log-transformed regressions were used to test for allometric growth and lines were compared by ANCOVA. No significant difference was found in the growth of the carapace for male and female crabs and relative growth in carapace length was negatively allometric. Abdomen growth in female 0. catharus showed a discontinuity between 35 and 40 mm cw indicating the pubertal molt. For prepubertal females and males, abdomen growth was isometric, contrasting with postpubertal females where abdomen growth was positively allometric. Male crabs between 15 and 100 mm cw showed positive allometric growth of the gonopod with a discontinuity corresponding to a carapace width of 40 mm. Relative growth of the gonopod of immature males was significantly greater than mature males. In 0. catharus the right chela or crusher was enlarged compared with the left chela. Relative growth of chela height in females was isometric and in males, negatively allometric. For female 0. catharus it was concluded that major differences in allometric growth were related to the onset of sexual maturity and the maturation of the gonads. Differences in the allometric growth of the male gonopod and male chelae are more likely related to mating or other behavioral adaptations.