Omobranchus punctatus (Teleostei: Blenniidae), an Exotic Blenny in the Southwestern Atlantic

The muzzled blenny Omobranchus punctatus (Valenciennes), native to the Indo-Pacific region, is recorded in the Southwestern Atlantic coast, inhabiting natural and artificial substrates in the proximities of three large Brazilian seaports (states of Bahia, Rio de Janeiro and Santa Catarina). Due to its habitat and habits, the introduction of this species was probably by ship or oil rigs, presumably associated within fouling. It is also argued that the muzzled blenny can maintain populations in natural and artificial (mariculture facilities) coastal environments in the Southwestern Atlantic.     

Development of microsatellites DNA markers in the cultivated seaweed,Gracilaria chilensis (Gracilariales,Rhodophyta)

The red algae Gracilaria chilensis is extensively cultivated for agar production. In spite of its commercial significance as the first algal resource in Chile, no information is available on the pattern of genetic diversity. In this paper, we isolated six polymorphic microsatellite markers from a G. chilensis‐enriched DNA library. Genetic diversity was assessed in two natural populations revealing relatively low levels of heterozygosity ranging from 0.00 to 0.51. The six loci developed here are good candidates to assess the level of genetic resources within this species, which probably suffered from over‐exploitation in several localities along the Chilean coast.     

Nitrogen flow through a Brachionus/Chlorella mass culture system

A model of nitrogen flow is presented through the Brachionus plicatilis/Chlorella saccharophila mass (batch) culture system, from the initial input of inorganic nitrogen to the algal culture medium to the final production of rotifers, dissolved nitrogen and particulate nitrogen.A nitrogen budget was first formulated for B. plicatilis relating ingestion, excretion, egestion, somatic growth and reproductive growth. Measurements were made on rotifers from 20° and 10° cultures.The calculated model of nitrogen flow through the rotifer/algal batch culture system estimates the percentages of the original input nitrogen which will be incorporated into algal nitrogen, rotifer nitrogen and the particulate and dissolved nitrogen pools. It is suggested that the dissolved nitrogen pool could be recycled directly for use in subsequent algal culture.     

海水养殖生境中硫酸盐还原菌活性的抑制机制

【目的】海水养殖生境中的硫化物(H₂S)严重损害养殖生物健康,控制该条件下硫酸盐还原菌(sulfate-reducing bacteria,SRB)的代谢活性是有效抑制H₂S产生的重要途径。【方法】本研究利用稀释涂布-叠皿夹法对海水养殖生境底泥中SRB进行富集筛选,获得SRB菌株,通过投加硝酸盐对菌株产H₂S的活性进行抑制。【结果】获得的2株SRB Desulfovibrio sp.NY-1和Clostridium sp.NH-1,能够在35℃、pH为7.0及盐度为20–30 mg/L条件下,分别积累高达435和150 mg/L H₂S。硝酸盐不能有效抑制NY-1产H₂S的活性,基因调控作用以及缺乏将硝酸盐作为电子受体的酶体系是其不能被抑制的主要原因。硝酸盐对NH-1 H₂S产生活性有可逆性抑制,其具有硝酸盐异化还原成铵(dissimilatory nitrate reduction to ammonium,DNRA)的能力,优先利用硝酸盐作为电子受体。DNRA作用下的中间代谢产物亚硝酸盐是有效抑制菌株NH-1产H₂S活性的主要原因,其抑制机理主要为抑制菌株的生长繁殖。【结论】硝酸盐对不同SRB菌株具有不同的抑制机制和效果,在进行硫化物污染控制前需要对产生硫化物的SRB菌群进行分析判别。     

海水养殖生态系统健康综合评价:方法与模式

我国海水养殖业快速、大规模发展的同时给生态系统带来巨大的压力,养殖自身的健康和持续发展也受到影响。为了评估海水养殖生态系统所承受的环境压力、系统的状态和发展趋势,以海湾养殖生态系统为典型,根据系统性、动态性、生态-社会-经济相结合的原则,构建了基于指标体系法和层次分析法的海水养殖生态系统健康综合评价的方法与模式,以期为养殖海域生态系统健康评估和适应性管理提供科学工具。     

Symbiosis initiation in the bacterially luminous sea urchin cardinalfish Siphamia versicolor

To determine how each new generation of the sea urchin cardinalfish Siphamia versicolor acquires the symbiotic luminous bacterium Photobacterium mandapamensis, and when in its development the S. versicolor initiates the symbiosis, procedures were established for rearing S. versicolor larvae in an aposymbiotic state. Under the conditions provided, larvae survived and developed for 28 days after their release from the mouths of males. Notochord flexion began at 8 days post release (dpr). By 28 dpr, squamation was evident and the caudal complex was complete. The light organ remained free of bacteria but increased in size and complexity during development of the larvae. Thus, aposymbiotic larvae of the fish can survive and develop for extended periods, major components of the luminescence system develop in the absence of the bacteria and the bacteria are not acquired directly from a parent, via the egg or during mouth brooding. Presentation of the symbiotic bacteria to aposymbiotic larvae at 8-10 dpr, but not earlier, led to initiation of the symbiosis. Upon colonization of the light organ, the bacterial population increased rapidly and cells forming the light-organ chambers exhibited a differentiated appearance. Therefore, the light organ apparently first becomes receptive to colonization after 1 week post-release development, the symbiosis is initiated by bacteria acquired from the environment and bacterial colonization induces morphological changes in the nascent light organ. The abilities to culture larvae of S. versicolor for extended periods and to initiate the symbiosis in aposymbiotic larvae are key steps in establishing the experimental tractability of this highly specific vertebrate and microbe mutualism.     

Benthic foraminifera at a scallop aquaculture site in Minonosok Bay,the sea of Japan

The species composition and distribution of benthic foraminifera at a scallop aquaculture site in shallow Minonosok Bay (southern Primorye) were studied. Ninety-three species of benthic foraminifera were found in Minonosok Bay in 1998 and 83 species in 2000; representatives of the families Elphidiidae, Discorbidae, Trochamminidae, and Ataxophragmiidae dominated. In 1998, the calcareous species Cribroelphidium frigidum was most abundant; in 2000, calcareous Protelphidium asterotuberculatum and arenaceous species Trochammina inflata and Eggerella advena were dominant. The effect of scallop cultivation on the distribution of benthic foraminifera was local. The species composition and population density of foraminifera directly under scallop cages were decreased, compared to areas of the bay where there were no mariculture operations.     

Cultivation of the edible green seaweed <Emphasis Type="Italic">Gayralia</Emphasis> (Chlorophyta) in southern Brazil

During the last two decades, the monostromatic green seaweed Gayralia sp. has been harvested sporadically by local fishermen on the Paraná coast of southern Brazil and sold to Japanese restaurants. However, the production is erratic and its economic impact very small. This paper provides basic information about a technique to cultivate this seaweed on suspended nets in Paranaguá Bay, southern Brazil, aiming to develop a more reliable and sustainable source of income for impoverished coastal dwellers. Gayralia sp. occurs year round in the region, usually growing on mangrove stems and roots. Polypropylene nets (10 m long × 1 m wide with 16 cm mesh) were placed close to the mangrove fringe. Recruitment occurred year round reaching a peak of 500 recruits m⁻² during early spring. Higher recruitment occurred at periods of low temperature (21–23°C) and high salinity (30–33 psu). Growth rates of Gayralia sp. ranged from 5.75 ± 0.56% to 6.50 ± 0.43% day⁻¹ during the winter and from 1.43 ± 1.65% to 4.65 ± 2.17% day⁻¹, during the summer. Production ranged from 22 ± 6 g m⁻² DW in June to 58 ± 21 g m⁻² DW in September 2004 in 45 days after zooid settlement. The simplicity of the cultivation method, reasonable growth rates and extensive favorable area for cultivation suggest that mariculture of Gayralia sp. may become a good alternative of income for the local inhabitants.     

Effects of temperature and ammonium on growth,pigment production and nitrogen uptake by four species of <Emphasis Type="BoldItalic">Porphyra</Emphasis> (Bangiales,Rhodophyta) native to the New England coast

Porphyra is one of the world’s most valued maricultured seaweeds and has been cultivated for several hundred years in Asia. The objective of this study was to produce critical information as a guide for the selection of an appropriate Porphyra species from coastal New England for the development of a land-based aquaculture system. Four Northwest Atlantic Porphyra species: P. leucosticta, P. amplissima, P. linearis and P. umbilicalis, were cultivated for 1 and 2 weeks at saturated light intensities (100–150 μmol photons m⁻²s⁻¹) and six combinations of ammonium (25 and 250 μmoles L⁻¹) and temperature (10, 15 and 20°C). Specific growth rate (SGR) increased with decreasing temperature in P. leucosticta, P. linearis and P. umbilicalis and increased with increasing temperature in P. amplissima. The SGR of all species was greater at the higher ammonium concentration. Porphyra linearis had the highest SGR, increasing in biomass by approximately 16% day⁻¹. Phycoerythrin (PE) content was higher at 10°C and 250 μmoles L⁻¹ in all species except P. amplissima. The PE content, measured as fresh weight (FW), of P. linearis (29 mg g⁻¹ FW⁻¹) and P. umbilicalis (26 mg g⁻¹ FW⁻¹) was significantly higher than the other two species. Tissue nitrogen content of all species measured in dry weight was on average 1.45% higher at 250 μmoles L⁻¹ than at 25 μmoles L⁻¹ ammonium concentration. Porphyra umbilicalis had the highest tissue nitrogen contents (6.76%) at 10°C and 250 μmoles L⁻¹ ammonium. Based on these results, P. linearis and P. umbilicalis should be considered as potential candidates for bioremediation with finfish and shellfish mariculture.