The study of bacteria on artificially incubated noble crayfish eggs

Data on the abundance of heterotrophic bacteria on the surface of artificially incubated noble crayfish (Astacus astacus L.) eggs are presented. The highest abundance of heterotrophic bacteria was observed on crayfish juveniles (stage 1). The abundance of bacteria in the water of the incubator’s system was found to be considerably lower than that on crayfish eggs, and bacteria counts on dead eggs were a 100 times lower than on healthy eggs. The abundance of pigmented bacteria on dead eggs was considerably higher than on healthy eggs. Aeromonas and Pseudomonas bacteria, constituting up to 70% of all bacteria identified, were found to be dominant on noble crayfish eggs.     

The geomagnetic environment in which sea turtle eggs incubate affects subsequent magnetic navigation behaviour of hatchlings

Loggerhead sea turtle hatchlings (Caretta caretta) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around the nest. In orientation experiments, hatchlings that developed in the normal ambient field oriented approximately south when exposed to a field that exists near the northern coast of Portugal, a direction consistent with their migratory route in the northeastern Atlantic. By contrast, hatchlings that developed in a distorted magnetic field had orientation indistinguishable from random when tested in the same north Portugal field. No differences existed between the two groups in orientation assays involving responses to orbital movements of waves or sea-finding, neither of which involves magnetic field perception. These findings, to our knowledge, demonstrate for the first time that the magnetic environment present during early development can influence the magnetic orientation behaviour of a neonatal migratory animal.     

Tubulin dynamics during the cytoplasmic cohesiveness cycle in artificially activated sea urchin eggs

Sedimentation studies and [³H]colchicine-binding assays have demonstrated a relationship between the cytoplasmic cohesiveness cycles and the changes in tubulin organization in Paracentrotus lividus eggs activated by 2.5 mM procaine. The same amount of tubulin (20–25 % of the total egg tubulin) is involved in these cyclic process and appears to undergo polymerization and depolymerization cycles. Electron microscopy studies reveal that the microtubules formed during these cytoplasmic cohesiveness cycles are under a particulate form which is sedimentable at low speed. Activation experiments carried out in the presence of cytochalasin B (CB) show that the increase in the cytoplasmic cohesiveness is highly reduced while tubulin polymerization and depolymerization cycles and pronuclear centration are not affected. Although tubulin or actin polymerization can be independently triggered in procaine-activated eggs, the increase in cytoplasmic cohesiveness requires the polymerization of both proteins. However, the cytoplasmic cohesiveness cycles appear to be regulated by tubulin polymerization and depolymerization cycles.     

Histochemical and immunohistochemical studies of the gonads and paramesonephric ducts of male and female hatchlings of loggerhead sea turtles (Caretta caretta)

The sex of neonatal sea turtles is difficult to determine, because neonates lack heteromorphic sex chromosomes and dimorphic external characteristics; internal dimorphic morphology is defined at hatching. We used histochemical staining and made measurements in the gonads and paramesonephric ducts (PD) of both sexes to determine structural differences in female and male loggerhead sea turtle (Caretta caretta) hatchlings. We detected differences in the gonads and PD between the sexes including the amounts of mucopolysaccharides, collagen and elastic fibers. We determined that the thickness of the gonadal cortex and the diameter of the PD lumen are reliable sex-specific characteristics. We also assessed immunolocalization of aromatase, an enzyme complex that converts androgens to estrogens, and found differences in the localization and intensity of aromatase immunostaining in the gonads and PD of female and male hatchlings. Comprehensive studies of the sexual differences of sea turtles are important for conservation programs.     

Fidelity and over-wintering of sea turtles

While fidelity to breeding sites is well demonstrated in marine turtles, emerging knowledge of migratory routes and key foraging sites is of limited conservation value unless levels of fidelity can be established. We tracked green (Chelonia mydas, n=10) and loggerhead (Caretta caretta, n=10) turtles during their post-nesting migration from the island of Cyprus to their foraging grounds. After intervals of 2-5 years, five of these females were recaptured at the nesting beach and tracked for a second migration. All five used highly similar migratory routes to return to the same foraging and over-wintering areas. None of the females visited other foraging habitats over the study period (units lasted on average 305 days; maximum, 1356 days), moving only to deeper waters during the winter months where they demonstrated extremely long resting dives of up to 10.2h (the longest breath-holding dive recorded for a marine vertebrate). High levels of fidelity and the relatively discrete nature of the home ranges demonstrate that protection of key migratory pathways, foraging and over-wintering sites can serve as an important tool for the future conservation of marine turtles.     

Accumulation of trace metals in eggs and hatchlings of Chelonia mydas

BackgroundThe objective of this study was to verify the accumulation of trace metals in eggs and hatchlings of Chelonia mydas, evaluating if metal accumulation is originated from maternal transfer and/or from the incubation environment. Other assessments were also performed, as metal distribution in different tissues (blood, kidney, liver, muscle, and turtle shells) of newly hatched turtles, and genotoxic analysis, to verify possible damages caused by the presence of metals.MethodsThe assessments were carried out by quantifying Cd, Ni, Pb, Mn and Fe in egg sample collected during laying time (eggshells (ELT) and egg content (EC)), eggshells from newly hatched turtles (ENH), hatchlings tissues (H - blood, kidney, liver, muscle, and shell)) (n = 18 for each biological sample - 3 of each nest) and nest sediments (n = 6, one of each nest). Comparative analysis were made between ELT and ENH, as well as between egg content (EC) and the sum of tissue samples from hatchlings, using Mann-Whitney hypothesis test (p < 0,05). The amount of metals in different hatchling was quantified and followed by the Dunn post-test. A principal component analysis (PCA) was also employed.ResultsMetals studied were found in all investigated samples. The concentration of a great amount of investigated metals was significantly higher (P=<0.001) in eggshells from ENH than in ELT. An increase in Cd (2.16-fold), Pb (3.47-fold), Fe (6.83-fold) and Mn (195.57-fold) concentration was noticed in ENH. We also observed an increase in Fe (1.59-fold), Mn (1.74-fold) and Ni (1.59-fold) concentration in hatchling, when compared with EC, due to transfer from nest sediments. In relation to the hatchling’s tissues, blood was shown to accumulate higher concentrations of Ni and Pb, while shells accumulated more Cd and Fe, and Mn is more associated with liver and kidney. Fe was the highest accumulated metal in both tissues, and muscles presented discrete concentrations of Ni, Mn, and Pb. A mean concentration of 1.25‰ MN was obtained in C. mydas hatchlings, indicating that the accumulation of metals in hatchlings didn’t cause toxicology effects.ConclusionHatchlings accumulate metals through the maternal and sediment transfer, although the levels of metal accumulation were not enough to cause genotoxic damage.     

Population genetics and phylogeography of sea turtles

The seven species of sea turtles occupy a diversity of niches, and have a history tracing back over 100 million years, yet all share basic life-history features, including exceptional navigation skills and periodic migrations from feeding to breeding habitats. Here, we review the biogeographic, behavioural, and ecological factors that shape the distribution of genetic diversity in sea turtles. Natal homing, wherein turtles return to their region of origin for mating and nesting, has been demonstrated with mtDNA sequences. These maternally inherited markers show strong population structure among nesting colonies while nuclear loci reveal a contrasting pattern of male-mediated gene flow, a phenomenon termed 'complex population structure'. Mixed-stock analyses indicate that multiple nesting colonies can contribute to feeding aggregates, such that exploitation of turtles in these habitats can reduce breeding populations across the region. The mtDNA data also demonstrate migrations across entire ocean basins, some of the longest movements of marine vertebrates. Multiple paternity occurs at reported rates of 0-100%, and can vary by as much as 9-100% within species. Hybridization in almost every combination among members of the Cheloniidae has been documented but the frequency and ultimate ramifications of hybridization are not clear. The global phylogeography of sea turtles reveals a gradient based on habitat preference and thermal regime. The cold-tolerant leatherback turtle (Dermochelys coriacea) shows no evolutionary partitions between Indo-Pacific and Atlantic populations, while the tropical green (Chelonia mydas), hawksbill (Eretmochelys imbricata), and ridleys (Lepidochelys olivacea vs. L. kempi) have ancient separations between oceans. Ridleys and loggerhead (Caretta caretta) also show more recent colonization between ocean basins, probably mediated by warm-water gyres that occasionally traverse the frigid upwelling zone in southern Africa. These rare events may be sufficient to prevent allopatric speciation under contemporary geographic and climatic conditions. Genetic studies have advanced our understanding of marine turtle biology and evolution, but significant gaps persist and provide challenges for the next generation of sea turtle geneticists.     

Heavy metals in marine turtle eggs and hatchlings in the Mediterranean

Abstract

The concentrations of cadmium, lead, iron, copper and zinc were analysed in Loggerhead Turtle (Caretta caretta) hatchling samples (eggshells, remaining yolk, and liver) from beaches of southwest Turkey. Cd, Pb, Fe, and Cu concentrations were higher in embryo liver than in yolk. Zn concentration was higher in yolk. Hg concentrations in all yolk samples were below the detection limit, but levels could be measured in some embryo livers.     

Water loss from eggs of domestic fowl and calcium status of hatchlings

Water balance in eggs of domestic fowl was manipulated by drilling holes (each 3 mm in diameter) through the calcareous layer into the air cell on day 10 of incubation. Water loss between days 0 and 18 averaged 6 g for eggs in the control group (no hole) but increased to 8, 12, and 15 g for eggs with 1, 2, or 3 holes, respectively. Hatching success was 79–87% for eggs with 0–2 holes through the eggshell but only 43% for eggs with three holes. Live mass of hatchlings declined as the number of holes drilled in the eggshell increased, but dry mass of carcasses was unaffected by the treatments. The quantity of Ca²⁺, Mg²⁺, and phosphorus in residual yolks and yolk-free carcasses of hatchlings was not influenced by the amount of water lost from eggs. Plasma Ca²⁺ and Mg²⁺ were elevated in hatchlings from eggs with high rates of water loss. The inability to regulate plasma Ca²⁺ may be a negative consequence of excessive water loss and could contribute to increased mortality of embryos.     

Structure of shells from eggs of kinosternid turtles

Shells from eggs of five species of kinosternid turtle (Sternotherus minor, Kinosternon flavescens, K. baurii, K. Hirtipes, and K. alamosae) were examined with light and scanning electron microscopy. Except for possible differences among species in thickness of eggshells, structure of shells from all eggs was similiar. In general, kinosternid turtles lay eggs having a rigid calcareous layer composed of calcium carbonate in the form of aragonite. The calcareous layer is organized into individual shell units with needlelike crystallites radiating from a common center. Most of the thickness of the eggshell is attributable to the calcareous layer, with the fibrous shell membrane comprising only a small fraction of shell thickness. Pores are found in the calcareous layer, but they are not numereous. The outer surface of the eggshells is sculptured and may have a thick, organic layer in places. The outer surface of the shell membrane of decalcified eggshells is studded with spherical cores which presumably nucleate growth of shell units during shell formation. The shell membrane detaches from eggs incubated to hatching, carrying with it remnants of the calcareous layer. Such changes in shell structure presumably reflect withdrawal of calcium from the eggshell by developing embryos.     

Temperature and the life-history strategies of sea turtles

1. 1. Sea turtles have a high fecundity, high mortality, great longevity life history strategy.

2. 2. With the exception of the leatherback, turtle distribution is constrained by the 20°C surface isotherm.

3. 3. All sea turtles exhibit temperature-dependent sex determination (TSD) with pivotal temperatures close to 29°C.

4. 4. It is suggested that hatchling sex ratio will vary chaotically because of TSD.

5. 5. Because of TSD and natal homing, sea turtles are likely to be adversely affected by global warming.

6. 6. TSD and global warming have implications for conservation/management of sea turtles.

     

中国海龟标志方法纵览

广东惠东港口海龟湾是我国目前唯一的海龟国家级自然保护区,在1985—2005年的21年间,共保护绿海龟安全上岸产卵1184头次,标志放流成年雌海龟125头,近几年又开展了海龟卫星追踪试验,并获得了丰富的研究数据。海龟个体标志为开展科学研究活动提供了极大的方便,有利于建立龟口管理档案,完善海龟标识溯源信息系统。有关海龟生物学生态学的许多问题,例如母龟每季产卵次数、巢间期、产后洄游路线、母龟生殖周期、每一族群产卵地和觅食地分布。     

Eradication of Arizona hinshawii from artificially infected turtle eggs

Turtle eggs, 24 h old, were infected with Arizona hinshawii and treated 48 h later with gentamicin sulfate (Garasol; Shering Corp., Allantown, N.J.) by pressure differential egg dip treatment to ascertain the concentration of this reagent required to eradicate this pathogen from eggs. Infected eggs treated with 1,000 or 1,500 micrograms of gentamicin per ml of dip solution eliminated detectable A. hinshawii from eggs as determined by testing shells and embryo-yolk homogenates of 12-day-old eggs and the gastrointestinal tracts, kidneys, livers and gall bladders, and yolks of 50-day-old embryos. Treated eggs produced hatchlings which did not excrete detectable A. hinshawii at 72 h or 30 days after hatching, nor was this organism recovered from the visceral organs of these hatchlings when necropsied 30 days after hatching. Bacteriological assays on infected nontreated eggs showed that greater than 70% of the eggs harbored A. hinshawii, and eggs in this group produced hatchlings which actively excreted and harbored A. hinshawii. Eggs not infected or treated also produced turtles which excreted and systemically carried A. hinshawii and Salmonella spp. though not at the same level as did the turtles produced from infected, nontreated eggs.     

Migration cues and timing in leatherback sea turtles

Atlantic leatherback sea turtles migrate annually from foraginggrounds off eastern Canada and the northeastern United Statesto southern foraging and breeding areas. Using Cox's proportionalhazards model, we investigated the individual timing of thesouthward migrations of 27 turtles equipped with satellite-linkedtransmitters off Nova Scotia compared with turtle characteristicsand satellite-measured ocean variables. Latitude, longitude,1-week lagged average sea surface temperature, and 1-week laggedaverage chlorophyll-a concentration appear to influence theprobability of departure. Higher temperature and, in the northernrange of the study, higher chlorophyll concentration increaseddeparture rates, perhaps due to the acceleration of the lifecycle of the leatherback's gelatinous prey and/or increasedfeeding efficiency in these areas. This study highlights theopportunity to use satellite telemetry and environmental datato examine the cues for and timing of animal migrations andexpands the study of migration timing to include a new speciesand environment.     

Increased free Ca2+ levels delay the onset of mitosis in fertilized and artificially activated eggs of the sea urchin

Increasing free Ca2+ in the cytoplasm of fertilized and NH4OH- or A23187-activated eggs of Strongylocentrotus purpuratus and Lytechinus variegatus resulted in significant delays in the onset of mitosis. The increased Ca2+ levels were induced by addition of the calcium ionophore A23187 to suspensions of fertilized and activated eggs, or by fertilizing NH4OH-activated eggs. The delays may represent a temporary inhibition of the activation and activities of the mitotic proteins. It is postulated that relatively high free Ca2+ levels in the cytoplasm prevents activation of the mitotic proteins. Active Ca2+ sequestration is therefore suggested as an essential factor in the onset and progression of early mitosis.