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Results in Journal Sexuality and Early Development in Aquatic Organisms: 15

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, Ji Westgaard, T Pedersen
Sexuality and Early Development in Aquatic Organisms, Volume 1, pp 133-142; https://doi.org/10.3354/sedao00013

Abstract:
-Large offshore and small inshore populations of Atlantic cod Gadus morhua L. display differences in migratory patterns and settling regimes, but little is known about possible differences in spawning behaviour. Cod presumably of the Norwegian coastal cod type were therefore sampled during 7 spawning seasons (2002-2013) in Malangen, northern Norway. A spawning site in neighbouring Balsfjord was sampled during 5 consecutive spawning seasons (2002-2006). Length, weight, sex and maturity stage were recorded for each individual fish (n = 995). To verify their population assignment, frequencies of the 2 different Pan I (pantophysin) alleles were measured in 6 sampling years in Malangen and 3 in Balsfjord (n = 728). During all survey years there was an extreme skewed sex ratio at the spawning sites. In 6 of 7 seasons in Malangen, 8–9 of 10 fish were males, and in Balsfjord 9 of 10 fish were males on average, indicating some form of lekking behaviour among the spawning fish. Average size of the fish varied among years and also between sexes in individual years, although not consistently. The smallest proportion of mature fish was seen in Malangen in the year with the earliest sampling date (23 February). This was also the sample with the least skewed sex ratio (6.5 of 10 fish were males). The frequency of the Pan IA allele of the Malangen cod was highly stable among years at close to 90%, showing that this spawning ground is exclusively used by coastal cod. In Balsfjord, frequencies of the Pan IA allele were lower (67-78%). This fjord is suggested to be more penetrable for the migratory NE Arctic cod with their high frequencies of the Pan IB allele, making it a less exclusively coastal cod residence. In both fjords, length of mature males but not females varied among the Pan I genotypes
Sven Thatje, Kathryn E Smith, , P.A. Tyler
Sexuality and Early Development in Aquatic Organisms, Volume 1, pp 109-116; https://doi.org/10.3354/sedao00011

Abstract:
The deep-sea squat lobster Kiwa tyleri (also known as yeti crab) is the dominant macroinvertebrate inhabiting hydrothermal vents on the northern and southern segments of the East Scotia Ridge in the Southern Ocean. Here, we describe the first zoeal stage of the species—which is morphologically advanced—and provide evidence for its lecithotrophy in development. This morphologically advanced stage at hatching suggests that dispersal potential during early ontogeny may be limited. Adults of K. tyleri typically inhabit a warm-eurythermal, and spatially defined, temperature envelope of vent chimneys. In contrast, ovigerous females with late embryos are found away from these temperatures, off the vent site. This implies that at least part of embryogenesis takes place away from the chemosynthetic environment. Larvae are released into the cold waters of the Southern Ocean that are known to pose physiological limits on the survival of reptant decapods. Larval lecithotrophy may aid long developmental periods under these conditions and facilitate development independent of pronounced seasonality in primary production. It remains uncertain, however, how population connectivity between distant vent sites may be achieved
K Hamasaki, S Kato, Y Murakami, S Dan, S Kitada
Sexuality and Early Development in Aquatic Organisms, Volume 1, pp 93-107; https://doi.org/10.3354/sedao00010

Francisco Benítez-Villalobos, , Itandehui Sarai Gutiérrez-Méndez
Sexuality and Early Development in Aquatic Organisms, Volume 1, pp 13-24; https://doi.org/10.3354/sedao00003

Abstract:
The sea cucumber Holothuria fuscocinerea is among the most common holothurian species widely distributed in the Tropical Eastern Pacific Region and is becoming a potentially important fishery in Mexico. Nevertheless, there are no studies about its reproductive biology. This study analyzed several reproductive traits of H. fuscocinerea based on monthly time-series samples taken from April 2008 to March 2009 at La Entrega Bay, Oaxaca, in the Mexican tropical Pacific. Sex ratio, gonad development stages (GDS), reproductive cycle, diameter and distribution of oocytes, and fecundity were determined. Reproductive indices (the gonadosomatic index [GSI] and maturity index [MI]) were calculated, and their relationship with some environmental factors (temperature, rainfall, salinity, and pH) was evaluated. H. fuscocinerea is a gonochoric holothuroid, and its annual ratio of males to females was not significantly different from 1:1. Four GDS (i.e. gametogenesis, mature, spawning, post-spawning) as well as one period of gonadal recovery, which is ‘sexually undifferentiated’, were established. Spawning occurred from June to October in females and from April to September in males. Post-spawning of females and males and recovery stages coincided from October to January. Mean fecundity was 2.9 ± 2.8 million oocytes per female, with ovaries exclusively comprised of vitellogenic oocytes from June to September. GSI and MI values showed similar variations in accordance with the reproductive cycle, and GSI showed a relationship with rainfall season. Seasonal rainfall may act as a cause of the seasonal reproductive pattern observed in H. fuscocinerea.
O Kinne, K Anger, Jp Thavamani, M Seaman, Jd Austin
Sexuality and Early Development in Aquatic Organisms, Volume 1; https://doi.org/10.3354/sedao00001

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