Intra-annual and long-term patterns in the reproductive cycle of giant scallops Placopecten magellanicus (Bivalvia: Pectinidae) from Passamaquoddy Bay, New Brunswick, Canada

The spawning biology of the tropical abalone Haliotis asinina on Heron Reef, Australia, was investigated to identify putative environmental and endogenous factors controlling spawning. Spawnings by H. asinina were highly regular and, in comparison to most other haliotids and marine invertebrates, frequent and extremely synchronous. These events appeared to be regulated by more than 1 environmental cue. The spawning season of H. asinina extends from October to April and is associated with an increase in water temperature. During the spawning season, recently captured abalone, housed in flow-through aquaria, released gametes for 2 nights every 2 wk during the new and full moons. However, the exact date of spawning did not correlate precisely with the lunar cycle. Occasionally the spawning events between 2 populations of H. asinina on Heron Reef that were 1.5 km apart differed by 1 d, suggesting that differential tidal regimes might influence the date of spawning. The population that was exposed to slightly longer spring low tides occasionally spawned 1 d earlier.In the aquaria, the onset of male spawnings was earlier than the onset of female spawnings by an average of 31 min. The time of spawning of either sex was highly correlated with the evening high tide; males spawned an average of 19 min prior to the high tide, and females spawned 11 min after the high tide. Spawnings were highly synchronous amongst individuals, with 90% commencing spawning within 89 min of the first individual that spawned. A greater percentage of individuals spawned when in the presence of the opposite sex and the frequency of male ejaculation was greater when in the presence of females. Synchronous spawning patterns persisted for 6 wk in H. asinina maintained in aquaria; after this period, spawnings continued but were irregular and asynchronous. We propose that low tide exposure and time of high tide indirectly regulate the date and time of spawning respectively, and that these tidal elements influence the spawning biology of H. asinina by maintaining endogenous rhythms that persist in non-tidal environments for at least 6 wk.

Section: Discussionmentioning

confidence: 99%

“…For example, the spawning behaviour of the scallop Placopecten magellanicus within 1 bay is tidally cued and sometimes differs between populations (Parsons et al 1992). In addition, foraging and spawning activities of siphonarian limpets are cued to low tides, but vary between habitats (Iwasaki 1995).…”

Section: Discussionmentioning

confidence: 99%

Pattern, synchrony and predictability of spawning of the tropical abalone Haliotis asinina from Heron Reef, Australia

Counihan¹,

McNamara²,

Souter³

et al. 2001

“…Often these indices show a uniform and dramatic drop after a putative spawning event (e.g. Parsons et al 1992). From these data and observations of mass spawnings, it is sometimes assumed that spawning synchrony is extremely high (e.g.…”

Section: Discussionmentioning

confidence: 99%

In situ measures of spawning synchrony and fertilization success in an intertidal, free-spawning invertebrate

Marshall¹

2002

The rocky intertidal zone has the potential to be one of the harshest environments for free-spawning organisms, but empirical data on fertilization success are scarce. Here, I report on an intertidal, solitary ascidian, Pyura stolonifera, which was observed to spawn at low tide. At a scale likely to be most important to gametes (metres, duration of tide), approximately 30% of individuals in the population were spawning synchronously. Spawned gametes remained in a viscous matrix and this appeared to minimise their dilution. Fertilization success varied greatly among individuals (0 to 92%) and was related to the distance to the nearest neighbouring spawner. Occasional wave wash facilitated the movement of sperm between spawners. Fertilization success in some individuals was limited by the scarcity of sperm whilst the experimental addition of sperm did not increase success in others.

“…Sea scallops of the size range we used can reach sexual maturity; their reproductive investment may rise to 20% (annual gamete production divided by gamete and somatic tissue production) by their second year (MacDonald 1984, Black et al 1993. We sampled the scallops in August, a time of gametogenesis (Parsons et al 1992, Bonardelli et al 1996. If reproductive effort was greater in wild than cultured scallops, this could have reduced the mass of tissues, notably muscle, relative to those of cultured scallops, as found by Rodhouse et al (1984) in a comparison of mussels on the shore and from suspended culture.…”

Section: Discussionmentioning

confidence: 99%

Comparison of cultured and wild sea scallops Placopecten magellanicus, using behavioral responses and morphometric and biochemical indices

Lafrance¹,

Cliche²,

Haugum³

et al. 2003

As the survival of juvenile scallops released onto the seabed is of critical importance in programs seeking to enhance scallop populations, the basis of the vulnerability of seeded cultured scallops needs to be understood. High mortality rates following seeding operations could reflect weaker predator escape responses by cultured scallops. Thus, we compared behavioral responses as well as morphometric and biochemical measurements of cultured and wild sea scallops Placopecten magellanicus (35 to 45 mm shell height) sampled in August 1999 in the Gulf of St. Lawrence, eastern Canada. Cultured scallops had larger somatic tissues and higher muscle energetic contents than their wild counterparts. This may reflect the more favorable temperatures and better food supply during suspension culture. When faced with the starfish predator Asterias vulgaris, cultured scallops responded with a greater number of claps, longer clapping period and faster recuperation of clapping performance. However, wild scallops had stronger shells and showed more intense escape responses (higher clapping rate) to the starfish. These differences contribute to making cultured scallops more vulnerable to predation by grasping predators (crabs) and asteroids.