Gonad Color Research Articles

Reproductive Aspects of Blue Swimming Crab (Portunus pelagicus) Landed on the South End Coast of East Lombok

This study aims to describe aspects of the reproductive biology of a blue swimming crab (Portunus pelagicus) that landed at the southern end of the coast of East Lombok during the period November 2023 to April 2024. The study used a descriptive design with a quantitative approach to measure and analyze data through direct observation. Data included carapace width, body weight, gonad maturity stages, and gonad somatic index (GSI) of P.pelagicus. The results showed that the male P.pelagicus population was more dominant than females every month. P.pelagicus body weight varied, with significant increases in certain months caused by spawning. Analysis of the relationship between carapace width and body weight showed positive allometric growth, with b values of 3.17 for males and 3.10 for females, indicating that body weight gain was faster than carapace width. The maturity stages of the P.pelagicus gonads were mostly at stages I and II, with a few reaching stages III and IV. The average gonad maturity stages increased from 2.42% in November to a peak of 5,83 % in February, then decreased in the following months. The primary spawning time occurs from December to February, characterized by changes in gonad color and a decrease in the body weight of the P. pelagicus after spawning. Hopefully, this study’s results can positively contribute to the sustainable management of crabs (P. pelagicus).

Life cycles and reproduction of Rhizostomeae.

In the present study we reviewed the life cycles and reproduction strategies of the order Rhizostomeae. We found 28 species with described life cycles representing ∼30% of the valid species. The metagenetic life cycle of most scyphozoans, which includes the benthic asexually-reproducing polyp and the pelagic sexually-reproducing medusa, is exhibited by all rhizostome species. Rhizostomeae are dioecious with only two exceptions described as hermaphroditic. Sexual dimorphism can be found in species with special external structures utilised for brooding but others show no sexual dimorphism despite the colour of mature gonads. Six asexual reproduction modes have been described for the production of new polyps but rhizostome polyps propagate through a main mode that differs among taxa. Species belonging to Dactyliophorae produce new polyps by podocysts whereas the Kolpophorae new polyps develop from free-swimming buds. The number of ephyrae formed per strobila differs between taxa with monodisc and polydisc strobilation in the Kolpophorae and Dactyliophorae, respectively. Given the low number of studied species it is expectable that new reproductive strategies will be discovered when additional species are investigated. We recommend increasing (1) descriptions on life cycles and reproductive strategies for a greater number of species, (2) attempts to locate the polyps in the field, (3) the study of species in their natural environment, to understand the population dynamics of Rhizostomeae and to clarify the potential of artificial structures to increase medusa populations. In addition, experimental studies are needed to improve our understanding of the factors affecting transitions between life cycle stages and medusa production rates.

Shell drilling and gonad biopsies provide a rapid, nonlethal method for in situ assessment of reproductive periodicity in a turbinid gastropod

ABSTRACT Reproductive data on marine molluscs are imperative for informing conservation and management strategies. Most methods for assessing reproductive periodicity are lethal, which could be unfavourable for fragile populations. This study aimed to trial a nonlethal, drill-biopsy technique for assessing the reproductive cycle in the turbinid gastropod, Turbo militaris. This technique was tested in the laboratory, where a small hole was drilled into the shell, from where a biopsy of the gonad was taken. The procedures resulted in zero mortalities and rapid recovery of the animals when returned to seawater. Sex was identified by viewing the gonad colour through the shell hole and confirmed by viewing gametes from a biopsy. Preservation of the female biopsy was investigated, with buffered formalin found to be the most suitable solution. The drill-biopsy method was also tested in the field; five (out of six) recaptured T. militaris had repaired the shell hole after 6 weeks, and two were recaptured on multiple occasions up to the end of this study, 10 months later. The size–frequency distributions of oocytes from female biopsies suggested an increase in mode size over 2 months with a shift towards a higher number of larger oocytes, supporting the practicality of this nonlethal approach to evaluate reproductive periodicity and sex determination. Nonlethal sampling is recommended for broad-scale studies and populations under stress; methods, such as the drill-biopsy technique, facilitate reproductive sampling without detriment to the target populations.

The Reproduction of Meretrix meretrix Clams in The Kambu River Estuary, Southeast Sulawesi

Meretrix meretrix is a degraded resource in Kendari Bay waters, but its reproductive pattern is not fully known.. This study aims to determine the level of gonad maturity, gonadal maturity index, fecundity and the size of the first gonad maturity of M. meretrix at the Kambu River estuary, Kendari Bay, Southeast Sulawesi. This research was carried out at the Kambu River estuary for 6 months from August 2021-January 2022. These clams were taken randomly representing all size classes as many as 300 birds during the study. M. meretrix were observed for gonad color and gonad development microscopically, then the length and weight of the gonads were measured using a caliper and analytical balance with an accuracy of 0.5 mm and 0.0001g, respectively. The results showed that the development of male and female gonads was relatively simultaneous, which was dominated by mature gonads (III-IV) in each month of observation. TKG I-V was found in every month of observation. The gonad maturity index of males and females were 4.92-6.00 and 5.53-6.32, respectively. The fecundity of M. meretrix ranged from 4882-85677 grains. The first mature size of the gonads of male and female M. meretrix is 20 mm.

Sex Determination of Sea Cucumber Acaudina rosettis from Madura Straits, Indonesia

Acaudina rosettis is one of the commercial sea cucumber species that is widely consumed on the east coast of Surabaya, East Java, Indonesia. Although its abundance in nature has begun to show signs of decreasing, studies on this species are still very limited. This study aimed to examine indicators that can be used to determine the sex of A. rosettis individuals. Acaudina rosettis samples were collected from Madura strait in the mid of Hijri month for three months. The sea cucumber samples were then dissected. Body wall without viscera and gonads was weighed. The gonads were then characterized macroscopically and microscopically, prepared into histological slides with hematoxylin-eosin staining. The results showed that A. rosettis samples could be classified into three sex groups based on the type of gamete cells observed in the tubules; male (spermatogenic), female (oogenic), and undetermined sex (no gamete cells found). Gonads had three colors; yellow, pink, and orange and were in five stages of reproductive phase; gametogenesis (G), mature (M), spawning (S), and post-spawning (PS). Male samples had yellow and orange gonads, female samples were pink and orange, and all undetermined sex were orange. The G gonads were yellow and orange, M were yellow and pink, while S and PS were orange. Body wall and gonad weight at the same reproductive phase did not show any difference between males and females. Based on the results, gonad color can be used as an indicator of sex determination, but only in G and M reproductive phases.

Assessing the potential of the unexploited Atlantic purple sea urchin, Arbacia punctulata, for the edible market

The global demand for sea urchin as seafood is currently unmet. Despite exploitation of > 40 species across the world, there is a need to identify other candidate species, especially in regions where diversification in production is sought where species are considered native. The Eastern US presents an opportunity to determine the marketability of the currently unexploited Arbacia punctulata which is naturally distributed from Massachusetts and southwards into the Gulf of Mexico. To determine whether A. punctulata had market potential, it was fed one of the following diets to determine whether the gonad tissue (uni) could be manipulated to increase gonad mass and improve gonad color for the market: dried Ulva lactuca, Salmon pellets (Skretting), Tilapia pellets (Ziegler) or an Urchinomics diet designed for sea urchins either fed for 8 weeks or 12 weeks. All of the pelleted feeds (Salmon, Tilapia and Urchinomics) increased gonad mass and altered the color. The colors of the uni were generally darker than the colors that the market would typically prefer but some individuals did exhibit colors which have been classed as acceptable to the European market. This work highlights that further research is worthwhile to assess the market potential of A. punctulata.

Temporal changes in sex-specific color attributes and carotenoid concentration in the gonads (roe) of the purple sea urchin (Paracentrotus lividus) provided dry feeds supplemented with β-carotene

The market value of sea urchin roe (female and male gonads) depends on several quality criteria, such as size, color, texture, and flavor. Sea urchins given dry pellet feed often produce large gonads, but the preferred bright orange color has been difficult to achieve without the inclusion of supplementary dietary carotenoids. Gonad color depends on carotenoid concentrations (CC), and is influenced by several factors, including diet and sea urchin sex. This study aimed to evaluate the impact of sea urchin sex, gonad size, and maturation level on gonad color and CC. Small Paracentrotus lividus urchins (18 mm test diameter) were fed every 48 h with three diets of similar proximate composition (protein: 31–33% dry matter DM, fat: 9–10% DM; carbohydrates: 45–46% DM). The diets were formulated with fishmeal, algae, and plant-based ingredients and supplemented with β-carotene (100 mg Kg−1). The nutritional trial was conducted in three recirculatory aquatic systems equipped with 40 L glass tanks guaranteeing triplicates by diet with an initial biomass of 5 g L−1. The gonadosomatic index (GSI), gonad maturity and color of 15 urchins per replica were analyzed at mid-trial (103 days, T1) and at the end of the trial (173 days, T2), and compare with initial condition (baseline). At each sampling event, the color of female (F) and male (M) gonads was analyzed using qualitative (four-level visual scale) and quantitative methods (Commission Internationale de l’ Eclairage CIE L*, a* and b* color parameters). Additionally, CC was determined by spectrophotometry in pooled samples freeze-dried gonads per replica and sex and compared with baseline. At T1, 59 females and 71 males were analyzed, and results showed that females presented larger (GSI = 7.50) gonads with higher CC (117.5 μg g−1 DM) than males (GSI = 5.16 and CC = 76 μg g−1). Female gonads also presented a more intense color (a* = 8.8, b* = 17.13) than males (a* = 5.1, b* = 12.49). At T2, 61 females and 62 males were analyzed and, except for a high percentage of female gonads classified as color grade I (57%), the differences on gonad color and CC between sexes identified in T1 became non-significant. In general, the gonad color tended to become lighter (L*, baseline: 34.8 and T2: 47.2) and yellower (b*, baseline: 12.5 and T2: 17.50), and CC decreased (baseline: 201.8 μg g−1 DM and T2: 31.6 μg g−1 DM) with increasing gonad weight (baseline: 0.16 g and T2: 0.77 g) and GSI (baseline: 3.0% and T2: 9.9%). In conclusion, this study shows that the carotenoid concentration and color attributes of sea urchin gonads are influenced by sea urchin sex and gonad size. The different diets and the carotene supplementation had little or no effect on the gonad CC and color attributes, indicating that the sources and concentrations of carotenoids in the diets were not sufficient to allow the accumulation of pigments in the gonads needed to enhance the color of P. lividus urchins.

Sensory profiling, liking and gonad composition of sea urchin gonads fed synthetic or natural sources of β-carotene enriched diets

Sea urchin gonads are considered a prized seafood product. Their market price depends on quality and appearance, mainly evaluated through colour. The desirable yellow-orange colour is determined by carotenoids deposition in the gonads, mainly the accumulation of echinenone, which depends on availability, uptake and bioconversion of β-carotene from dietary sources. Two β-carotene sources, a synthetic (SYN) and a natural (paprika, PAP) source, were tested at low (L) and high (H) incorporation target levels (100 and 250 mg β-carotene kg−1 feed) in diets for Paracentrotus lividus. A non-supplemented diet was used as a control (CTRL) diet. After eight weeks of feeding, all diets effectively increased gonad weight and somatic index in both sexes, without significant differences between treatments. Total carotenoid content and profile, lightness (L*) and texture of gonads did not vary significantly among dietary treatments. However, gonad redness (a*) and yellowness (b*) values were significantly higher in urchins fed the L_SYN diet than in those fed either with the CTRL or L_PAP diets; female displayed higher values than male. L_SYN also showed higher consumers´ acceptance when compared to the other diets and female displayed higher acceptance rates than male, probably due to the fact that females were more orange, appealing and pleasant compared with the yellow, grainy and not appealing males. Male fed L_SYN diet exhibited similar colour and carotenoid content compared to wild animals in the same stage of gonad maturation (stage III), but female differed significantly; however, neither of the sex demonstrated acceptance differences in relation to their wild counterparts. Diets with the lower β-carotene inclusion induced changes in gonad colour but not in carotenoid pigments. This suggests that gonad colour is not exclusively modulated by dietary carotenoid supplementation and that it may be affected by other sex-dependent nutritional or metabolic factors.

Algal supplements in formulated feeds: Effects on sea urchin gonad quality

In the effort to increase the commercial value of urchin gonads produced via roe enhancement aquaculture, a variety of formulated feeds have been tested to increase gonad production and improve colour and taste. The addition of dried algal supplements to formulated feeds can further enhance gonad quality, but the level of improvement is highly variable and algae or urchin species dependent. Here we test whether the inclusion of three types of dried algal supplements (Sargassum fallax, Ecklonia radiata, and Durvillea potatorum) added to a pellet-based formulated aquaculture feed could further enhance the colour, taste and gonad quality in the temperate urchin Heliocidaris erythrogramma during two 12 wk. gonad enhancement periods, April to June, and July to September. All feed types resulted in urchins with gonad indices (GIs) of commercially acceptable quantities (Apr-Jun: GI = 14.6%, Jul-Sep: GI = 14.9%). The proportion of marketable gonads (A + B grades) was significantly higher during the Jul-Sep (87.9 ± 3%, mean ± SE) compared to the Apr-Jun (76.6 ± 3%, mean ± SE) enhancement period, however, algal supplement type did not improve gonad colour, taste, or the proportion of marketable gonads when compared to the control feed. We conclude that additional algal supplements may fail to further improve roe quality if the base formulated feed used to roe enhance is already of a standard that produces a sufficient proportion (>70%) of marketable roe.

Turning waste into gold: Sustainable feed made of discards from the food industries promotes gonad development and colouration in the commercial sea urchin Paracentrotus lividus (Lamarck, 1816)

Development of sustainable aquaculture practices is a suitable solution to reduce the pressure on overexploited stocks of the Mediterranean sea urchin, Paracentrotus lividus, and to respond to the increasing market demand. To move forward the Blue Growth and following the principles of circular economy, a three-month feeding experiment was conducted to test a sustainable feed based on food processing discards on sea urchins. Two feed formulations differing on the proportions of the two main ingredients (endive outermost leaves and European anchovy discards in a ratio of 60:40 and 80:20 respectively) were prepared and tested on P. lividus gonad yield, development and quality. The results were compared with those of wild sea urchins to assess the differences with natural patterns. Both feed formulations promoted gonad growth resulting in a significantly higher percentage increase in gonad biomass compared with wild specimens (490%, 330% and 78% increase in gonad weight in the feed 60/40, 80/20 and wild sea urchins respectively). Similarly, GSI of reared sea urchins varied by about 3–12% and 14% for sea urchins fed with feeds 80/20 and 60/40 respectively, while that found in wild sea urchins varied by about 3–5%. Gonad development was also boosted by the provision of the sustainable feed, as sexual maturation was faster in reared specimens than in wild ones. At the end of the trial, reared sea urchins showed also a very high (> 90%) frequency of marketable gonad colour. Lastly, the formulation with a more balanced vegetal/animal ratio (feed 60/40) gave the best results overall, combining the highest GSI and the best gonad colouration. Outcomes of this study confirm the suitability of food processing discards as ingredients for sea urchin feeds, although further research is needed to evaluate the effects on nutritional quality and organoleptic features of sea urchin gonads.

Sensory profiling, liking and acceptance of sea urchin gonads from the North Atlantic coast of Portugal, aiming future aquaculture applications

Sea urchin gonads are receiving increasing attention for their exclusive sensorial attributes. However, the sensory profile of this highly demanded gourmet product has not yet been well described, and it may potentially help enhancing the gonads’ marketability and acceptability. The main goal of this study was to build a sensory profile of sea urchin (Paracentrotus lividus) gonads, to evaluate differences between sex, harvest location, as well as the impact of presentation on consumer acceptance. Sixty untrained panellists (regular consumers of seafood) were asked to evaluate eight samples of raw sea urchin gonads, divided by sex, harvest location and presentation (in a clear translucent glass bowl or inside a sea urchin test). The panellists evaluated overall liking and acceptance (Food Action Scale), followed by a Check-All-That-Apply (CATA) ballot with a list of 38 sensory attributes divided into four dimensions: appearance (9), odour (8), texture (7) and taste (14), launched in Sense Gest. From a three-way ANOVA, no significant effect of sex, harvest location and presentation were identified for both liking and acceptance. However, a significant interaction between presentation and sex was identified: females with gourmet presentation were rated higher than females presented in a bowl; and males presented in a bowl were favoured in relation to gourmet presentation. Sensory profiling clearly separates gonads according to sex, with females being more appealing than males that presented a milky white fluid. Gonads were also separated according to the presentation method: the white background of the bowl seemed to highlight the orange colour of females; the gourmet presentation favoured the females in relation to the males, mainly because the male gonad colour and white-colour exudate were emphasized by the background of the sea urchin test. Moreover, the gourmet presentation in both sexes was correlated with a fresh, tropical and pleasant odour. This study concluded that sea urchin with an orange gonad and a sweet, fresh and tropical flavour is preferable, which will allow future nutritional research efforts to be focused on the enhancement of these gonad attributes.

Effects of dietary fish oil and soya bean lecithin on gonad index, colour and biochemical composition of the purple sea urchin,Strongylocentrotus purpuratus(Stimpson 1857)

The effects of increasing soya bean lecithin (SL) levels (0%, 2% and 4% of diet dry matter, DM) at two fish oil (FO) levels (0% and 3% DM) on gonad index, colour and biochemical composition of Strongylocentrotus purpuratus were evaluated using a 3 × 2 factorial design with six iso‐nitrogenous formulated diets. All diets generated an increase in gonad index of more than 9%. Dietary FO had a positive effect on diet digestibility and accumulation of proteins in the gonad. Soy lecithin did not affect gonad composition, but improved its coloration, decreased gonad feed conversion ratio and increased gonad protein efficiency. There was a clear effect of diets on sea urchins gonad protein, ash and fatty acid content, in particular, decreasing the n‐3/n‐6 ratio associated with a decrease in 20:5n‐3 when SL levels increased. Nevertheless, 22:6n‐3 levels increased by week 12 in all treatments, and diets with SL increased the content of 20:4n‐6 in gonads. A decrease in bitter‐tasting amino acids such as histidine, cysteine, valine and methionine was observed in all treatments with a concomitant increase in isoleucine levels. We recommend using a diet containing 3% of FO and 2% of SL to increase food consumption, diet digestibility, improving marketable gonad colour and an increasing gonad n‐6 fatty acids and C22:6n‐3. In addition, the present study paves the way for future research in the use of FO and SL as an additive in diets for S. purpuratus towards the goal of increasing gonad size and nutritional quality.

SELEKSI INDUK MATANG GONAD PADA SIPUT GONGGONG Laevistrombus turturella

Siput gonggong Laevistrombus turturella merupakan siput laut yang banyak dikonsumsi masyarakat di Provinsi Kepulauan Riau sehingga populasinya diperkirakan menurun. Upaya pelestarian siput ini perlu dilakukan salah satunya dengan budidaya. Kegiatan budidaya memerlukan ketersediaan induk matang gonad. Tujuan penelitian ini adalah menganalisis ukuran induk siput gonggong matang gonad berdasarkan panjang cangkang dan warna gonad, serta mengevaluasi pengaruh paparan suhu berbeda terhadap kecepatan penentuan jenis kelamin induk. Panjang cangkang siput gonggong diukur dengan jangka sorong, kemudian dipecahkan untuk mengamati warna gonadnya. Data dianalisis dengan student t-test. Perlakuan paparan suhu air 15°C (P1), 20°C (P2), dan 30°C (P3). Tujuh ekor induk siput gonggong dimasukkan ke dalam akuarium sesuai perlakuan, durasi waktu keluar tubuh lunak siput gonggong dari cangkang dicatat. Data dianalisis dengan uji Kruskal Wallis. Hasil penelitian menunjukkan ukuran rata-rata panjang cangkang induk siput gonggong matang gonad dari laut Madong-Tanjungpinang adalah 63,449±5,352 mm (jantan) dan 66,953±5,876 mm (betina). Penentuan jenis kelamin siput gonggong dapat dipercepat dengan pemberian kejutan suhu dengan suhu air 20°C.

Gonad quality of sea urchin Tripneustis gratilla with different seaweed diets

ABSTRACT
 
 Gonad quality of sea urchin Tripneustis gratilla is influenced by consumed seaweed type. Therefore, this study was conducted to determine the type of seaweed as potential source of carotenoids and produce a good quality of sea urchin gonad. The study was conducted in two phases, namely first phase was to obtain the content of carotenoids and β-carotene from several species of seaweed; and second phase was to testify the seaweed that produced high quality of sea urchin gonad.This study used completely randomized design with 4 treatmens of macroalgae diets, namely: 1. Enhalus sp., 2. Sargassum sp., 3. Ulva sp., and 4. Eucheuma sp. Each treament was repeated three times. Measured parameters were gonad weight, gonad maturity index, gonad color quality, and gonad texture. The study result showed that Enhalus contained the highest carotenoid and β-carotene content with 1409.53 and 639.37 mg/kg respectively. The highest gonad weight was 2.8 g; gonad color and texture was good (score 3); and the highest gonad maturity index was 5.4% that obtained from sea urchin fed with Enhalus. Therefore, this study concludes that Enhalus is potential source of carotenoids for sea urchin T. gratilla diet that will produce a good quality of gonad.
 
 Keywords: carotenoid, diet, gonad quality, sea urchin, seaweed.

Macroscopic characteristics of the gonad maturity stages of dusky parrotfish Scarus niger

The dusky parrotfish Scarus niger is an important economic fish. Like other reef fish that have good taste, white and thick meat, and don’t have a lot of tiny bones, the dusky parrotfish is a fine food fish. The dusky parrotfish has a very wide distribution in tropical and subtropical sea waters. This study aimed to validate the maturity stage descriptions based on macroscopic characters. The results of this study are expected to be a reference in the study of the reproductive biology of dusky parrotfish and other parrotfishes, such as first maturity and the reproductive cycle. The samplings were done monthly at Makassar Fisheries Port from January 2018 to May 2019. The parameters measured were total length, body weight, gonad weight, gonad length and width, and liver weight. The observed aspect was the gonad colour and condition for both male and female fishes. Five stages of gonad maturity used to identify the gonad maturity stages were quite accurate. The accuracy was indicated by the gonadosomatic index (GSI) and hepatosomatic index (HSI) values that increased progressively from Stage I to IV. This accuracy validates macroscopic characters used for identifying the maturity stage of dusky parrotfish

Maturity stages of the redbreasted wrasse Cheilinus fasciatus

The redbreasted wrasse Cheilinus fasciatus is an ornamental fish exploited for the marine aquarium trade. Even though it has white flesh, the redbreasted wrasse is not popular as a food fish because the flesh is quite thin. The redbreasted wrasse is widely distributed in the Indian and Pacific Oceans. It lives in tropical waters at depths of 4 to 60 m and at temperatures of 23 to 27°C. The objective of this study was to describe the gonad maturity stages of this fish using macroscopic characteristics. Sampling was carried out at Makassar Fishing Port from January 2018 to May 2019. The parameters observed in both male and female specimens were gonad length, width, weight, and gonad colour. Each specimen was also weighed and measured. Five gonad maturity stages were identified and described: Stage I (Immature or transition), Stage II (Early maturation), Stage III (maturation), stage IV (mature) and Stage V (post spawning or spent). These stages were described based on macroscopic structure and morphometric parameters of the gonads. The five stages coincided with changes in the Gonadosomatic Index (GSI), indicating that the five stages were valid. These stages could be used as a practical reference for identifying gonad maturity and describing the reproductive cycle of the redbreasted wrasse C. fasciatus.

Can artificial diets be a feasible alternative for the gonadal growth and maturation of the sea urchin Paracentrotus lividus (Lamarck, 1816)?

AbstractParacentrotus lividus (Lamarck 1816) has high‐value reddish‐orange gonads that are regarded as a delicacy. In this study, three jellified diets have been tested for 90 days to assess the effect of different diets on P. lividus somatic and gonadal growth, gonad color, and reproductive state. All diets contained agar as a gelling agent and consisted of: maize and spinach (A); maize, spinach, and macroalga Laminaria digitata (B); and maize, spinach, and pumpkin Cucurbita maxima (C). Diet B was the most successful in promoting somatic growth with regard to test diameter (1.2 mm month−1) and total wet weight (79.9 mg ind−1 day−1). The individuals from Diet A presented a higher final gonadosomatic index (9.07 ± 2.39%) where all sea urchins initially presented with an index of 3.33 ± 0.02%. Diets A and C led to a marked advance (p < .05) in the gametogenic cycle (66.7% and 46.7% of the individuals with mature gametes, respectively), while Diet B resulted in less‐developed gonadal stages, which are more appropriate for commercial purposes in terms of sensorial characteristics appreciated by the consumers. The gonad color analyses confirmed a redder roe in females and also the suitability of C. maxima as a potential gonad color enhancer for P. lividus.

Gonadal cycle and spawning of date mussel Lithophaga lithophaga (L.) (Bivalvia: Mytilidae) in Egyptian water

This study describes the gonads of Lithophaga lithophaga (Linnaeus, 1758) inhabiting the coast of Alexandria City, Egypt, on the Southeastern Mediterranean Sea. Investigated samples were collected from five sites situated between Sidi Gaber and Montaza. Seven hundred and forty six individuals were collected through one year from December 2017 to November 2018. Two hundred and thirty eight specimens with shell length of 46.83 ± 12.28 and total weight of 7.29 ± 5.74 were selected representing the monthly abundance and were used for histological analysis. The sex of L. lithophaga is dioecious with no sexual dimorphism and distinct by the gonad color. However, differentiation of sex was accurately defined histologically. The investigated animals showed a statistically unbalanced sex ratio. The male to female ratio was 3.5:1. However, the results of the present study showed that the ratio of males decreased as the shell length increased. The developmental stages of gonads were identified as five stages. The spawning activity occurred during July and August, while the spent stage was found mostly in September. Furthermore, the results showed that L. lithophaga has one annual gonadal cycle. There is a clear correlation between the maximum values of condition index and meat yield of these studied date mussels with their spawning activity during July–August, followed by a decrease in these values from October to the following June. This result can be a more validating method to identify the reproductive conditions of L. lithophaga’s population. Finally, each gonad developmental stage was described microscopically in details for both sexes.

Reproduction of the Sea Urchin Echinometra mathaei (Echinoidea: Echinodermata) Found on Buleji, Rocky Coast, Pakistan, North Arabian Sea

The reproductive status of Echinometra mathaei was studied at rocky shore of Buleji, Pakistan, North Arabian Sea from April 2011 to November 2012. This study investigated reproduction of this species by histological examination in order to characterize the reproductive pattern and evaluate the relationship with temperature, salinity and chlorophyll-a. The gonad color was not related to sex, only histological examination of gonad demonstrates sex differences. The gonad index (GI) of males and females E. mathaei showed significant temporal variations being highest in April’11 and showed weak correlations with seawater temperature, salinity and chlorophyll-a. On the basis of gonadal histology E. mathaei showed seasonal spawning from autumn to winter (from September to January) which coincided with the peak of phytoplankton abundance in October–November in coastal waters of Pakistan. Spawning was synchronized between both sexes. The over-all sex ratio did not follow the 1:1 and was significantly in favor of females. Future studies on ecology of this species would contribute towards a better understanding and management of the rocky shore ecosystem of Pakistan.

Ready to harvest? Spine colour predicts gonad index and gonad colour rating of a commercially important sea urchin

An important problem limiting productivity and profitability of sea urchin aquaculture is the inability of producers to predetermine if sea urchins are ready for harvest. One way to overcome the 10–100% of lost production due to inopportune harvest times is to use external morphological characteristics to determine harvest readiness. To determine whether spine colour may be a useful indicator of harvest readiness, we tested whether there are relationships between spine colour and the size and colour of gonads of the commercially important sea urchin Tripneustes gratilla. Adult T. gratilla were grown in all combinations of three densities and three seawater exchange rates, simulating a range of environmental conditions occurring in culture systems. After six weeks, we measured the size and colour of gonads using standard protocols, quantified spine colour using colour rating and RGB (red, green, blue) intensity, and tested for relationships among these variables using linear models. The models identified significant positive relationships between spine colour predictors and gonad index and gonad colour rating. Our models indicated higher gonad indices were associated with brighter coloured spines, whilst gonads with the highest colour ratings were associated with stronger orange or red coloured spines. Patterns in spine colour identified by our models may reflect variation in colour producing pigments, carotenoids and naphthoquinones, in the epithelium. It is not clear why colour pigments in spines may depend on the colour and size of gonads, but it may be that healthy sea urchins that can grow large gonads also have sufficient energy to obtain and store colour pigments. Alternatively, colour pigments may provide health benefits that facilitate greater gonad size. Overall, our findings suggest that spine colour may be a suitable proxy for determining the harvest readiness of T. gratilla and possibly other sea urchins, but improvement in the reliability of our models and full automation of colour assessments are required before this novel technique can be implemented at commercial scales.