Ostrincola humesi sp. nov., a myicolid copepod (Poecilostomatoida) parasitic in rock oysters cultured in the Gulf of Thailand

A new species of poecilostomatoid copepod, Ostrincola humesi (Myicolidae), is described, based on specimens collected from the mantle cavity of the rock oyster, Saccostrea cucullata (Born), cultured in the Gulf of Thailand. A close comparison was made between the new species and Ostrincola koe Tanaka with which the new species was previously confused. A key to the nine species of Ostrincola is provided.     

植物激素与营养液配施对平菇产量和品质的影响

不同配比的ＧＡ＿３和ＫＴ与营养液配施,对平菇菌丝生长影响不同。ＧＡ＿３和ＫＴ的适当配比,能促进菌丝分枝生长,也能显著提高平菇子实体的产量和品质,但维生素Ｃ的含量有所下降。ＧＡ＿３和ＫＴ若与营养液配合施用,比单独施用更能发挥其促进作用。     

Edge effects influence the composition and density of reef residents on subtidal restored oyster reefs

Within estuarine and coastal ecosystems globally, extensive habitat degradation and loss threaten critical ecosystem functions and necessitate widescale restoration efforts. There is abundant evidence that ecological processes and species interactions can vary with habitat characteristics, which has important implications for the design and implementation of restoration efforts aimed at enhancing specific ecosystem functions and services. We conducted an experiment examining how habitat characteristics (presence; edge vs. interior) influence the communities of resident fish and mobile invertebrates on restored oyster (Crassostrea virginica) reefs. Similar to previous studies, we found that restored reefs altered community composition and augmented total abundance and biomass relative to unstructured sand habitat. Community composition and biomass also differed between the edge and interior of individual reefs as a result of species-specific patterns over small spatial scales. These patterns were only weakly linked to oyster density, suggesting that other factors that vary between edge and interior (e.g. predator access or species interactions) are likely more important for community structure on oyster reefs. Fine-scale information on resident species' use of oyster reefs will help facilitate restoration by allowing decision makers to optimize the amount of edge versus interior habitat. To improve the prediction of faunal use and benefits from habitat restoration, we recommend investigations into the mechanisms shaping edge and interior preferences on oyster reefs.     

Cryopreservation of spermatozoa of the American oyster, Crassostrea virginica Gmelin

Spermatozoa of the American oyster Crassostrea virginica were frozen to ?196 °C in concentrated Hanks' salt solution (2.6×) containing 8% dimethyl sulfoxide. About 0.2 ml of spermatozoa that were stored in liquid nitrogen for 68 days fertilized 91% of 65,600 eggs compared to fresh spermatozoa, which fertilized 92% of approximately the same number of eggs from the same females. Larvae resulting from fertilization of fresh eggs with 39-day-old cryopreserved spermatozoa appeared normal after 11 days.     

Wild gregarious settlements of Ostrea edulis in a semi‐enclosed sea lough: a case study for unassisted restoration

Ostrea edulis was once prolific throughout Europe and considered as the continent's native oyster. However, O. edulis currently exists in small fragmented assemblages where natural unaided recovery is rarely encountered. This research identified the small semi‐enclosed sea Lough of Strangford on the northeast coast of Northern Ireland as one of the few locations within Europe where the native oyster displayed gregarious natural rejuvenation. On close examination, four influential parameters appeared to assist in concentrated settlement; raised topographical cultch formations, shell coverage, the number of fecund in situ adults, and site protection. If these components were to be combined and managed as part of reintroduction and restoration initiatives, high‐density settlements and self‐sustaining populations may be possible. The research also identified that unregulated harvesting of intertidal O. edulis assemblages has the potential to seriously hinder natural recoveries. Indeed, the findings suggest that a review of policy in regards to intertidal hand gathering is necessary. However, naturally occurring high‐density settlements recorded during this research should be inspirational to all involved in the restoration of the native oyster.     

Do positive interactions between marine invaders increase likelihood of invasion into natural and artificial habitats?

Positive species interactions such as facilitation are important for enabling species to persist, especially in stressful conditions, and the nature and strength of facilitation varies along physical and biological gradients. Expansion of coastal infrastructure is creating hotspots of invasive species which can spillover into natural habitats, but the role of positive species interactions associated with biological invasions remains understudied. Theory suggests that stronger biotic pressure in natural habitats inhibits invasion success. In space-limited marine systems, sessile organisms can overcome this limiting resource by settling as an epibiont on a substrate organism – basibiont. Using a series of spatially extensive surveys, we explored the role of invasive and native basibionts in providing habitat for other invasive and native epibionts, and tested whether environmental context (i.e. if the receiving habitat was natural or artificial), altered ecological outcomes. Overall, provision of space by basibionts was more important for invasive epibionts than for native epibionts but was dependent on the environmental context. Invasive basibionts facilitated invasive epibionts in natural habitats, and appeared to be more important for native epibionts in artificial habitats respectively. Native basibionts facilitated invasive, but not native epibionts in both natural and artificial habitats. These results advance our understanding of facilitation and highlight the idiosyncratic nature of biofouling and epibiosis, and the potentially important influence of environmental context. The degree to which native habitat-forming species versus invasive habitat-forming species either do or do not facilitate other native or non-native species is a rich area for investigation. Experimental work is required to disentangle the processes underpinning these patterns.     

Establishing Restoration Strategy of Eastern Oyster via a Coupled Biophysical Transport Model

For marine fish and invertebrates, larval dispersal plays a critical role in determining connections among source and sink habitats, and the lack of a predictive understanding of larval dispersal is a fundamental obstacle to the development of spatially explicit restoration plans for marine populations. We investigated larval dispersal patterns of eastern oyster in an estuary along the Northern Gulf of Mexico under different simulation scenarios of tidal amplitude and phase, river discharge, wind direction, and larval vertical migration, using a coupled biophysical transport model. We focused on the dispersal of larvae released from the commercially exploited (Cedar Point, CP) and non‐exploited (Bon Secour Bay, BSB) oyster populations. We found that high flushing rates through the dominant inlet prevented larval exchange between the commercially exploited and non‐exploited populations, resulting in negligible connectivity between them. Variations in tidal amplitude, river discharge and wind direction played a more important role in the amount of larvae retained in Mobile Bay when they are released from CP than from BSB. Under most of the scenarios, larvae from BSB were retained around the spawning area, while larvae from CP showed a predominant westward flow. Net sinking behavior of late‐stage larvae increased larval retention in the bay, but physical transport showed a higher impact in the amount of larvae retained. These findings have enhanced our understanding of larval dispersal of eastern oyster in a wide, shallow estuarine system, and been used to establish spatially explicit strategies for oyster restoration in the Mobile Bay system, Alabama.     

Adaptation of oysters to life on soft substrates

In spite of their sessile nature, oysters of the genera Crassostrea, Ostrea and their allies are adapted to live on soft muddy bottoms. To provide them with secure attachment and to keep the animal above the surface of the mud, these soft-bottom oysters employ two basic strategies. They tend to be gregarious in their settlement, thereby providing one another with surfaces for attachment, and they form lightweight shells. In addition to these common characteristics, these oysters have followed different morphological pathways to live successfully on soft muddy bottoms. There are at least four types of morphologies: (1) relay-type succession (shells pile up on one another over many generations); (2) konbo-type elongation (both valves grow vertically upwards, the dorsal hinge remaining at the base, near the umbo); (3) cone-type elongation (the attached valve grows upwards and the free valve acts as a lid); and (4) lightweight recliners (bulky shells with lightweight fabrics and cavities within them). Judging from the variety of taxa that have adopted it and the sizes of their populations, the relay-type is the most successful of these strategies. Recliners were particularly common during the Mesozoic. The relay-type appeared in the Late Jurassic, becoming the dominant adaptive strategy during the Cenozoic.     

Influence of environmental variables on the growth and reproductive cycle of Crassostrea (Mollusca,Bivalvia) in Guaratuba Bay,Brazil

The production of oysters in Guaratuba Bay, in the state of Paraná, Brazil, is still a mixed activity of mariculture and extractivism. The sustainable development of this production requires the monitoring of environmental, genetic, reproductive, and zootechnical variables. This study evaluated the importance of these variables on Crassostrea oyster production. Data were obtained between September 2009 and February 2011 from six evaluations: water quality, oyster larvae in plankton, capture of oyster spat by artificial collectors, molecular identification of collected spat and larvae, continuous evaluation of the reproductive maturity stage of adult oysters, and zootechnical performance achieved by experimental production. Temperature, dissolved oxygen, and water transparency were the environmental factors that had the most influence on the reproductive cycle (e.g. gonadal development and spat capture) and on the growth of the oyster. The highest rates for spat uptake were recorded in the summer, coinciding with the peak of sexual maturity of adults. The growth of the oysters, in terms of the weight of the meat, was related to the gonadal stage.     

Selectively bred oysters can alter their biomineralization pathways,promoting resilience to environmental acidification

Commercial shellfish aquaculture is vulnerable to the impacts of ocean acidification driven by increasing carbon dioxide (CO₂) absorption by the ocean as well as to coastal acidification driven by land run off and rising sea level. These drivers of environmental acidification have deleterious effects on biomineralization. We investigated shell biomineralization of selectively bred and wild‐type families of the Sydney rock oyster Saccostrea glomerata in a study of oysters being farmed in estuaries at aquaculture leases differing in environmental acidification. The contrasting estuarine pH regimes enabled us to determine the mechanisms of shell growth and the vulnerability of this species to contemporary environmental acidification. Determination of the source of carbon, the mechanism of carbon uptake and use of carbon in biomineral formation are key to understanding the vulnerability of shellfish aquaculture to contemporary and future environmental acidification. We, therefore, characterized the crystallography and carbon uptake in the shells of S. glomerata, resident in habitats subjected to coastal acidification, using high‐resolution electron backscatter diffraction and carbon isotope analyses (as δ¹³C). We show that oyster families selectively bred for fast growth and families selected for disease resistance can alter their mechanisms of calcite crystal biomineralization, promoting resilience to acidification. The responses of S. glomerata to acidification in their estuarine habitat provide key insights into mechanisms of mollusc shell growth under future climate change conditions. Importantly, we show that selective breeding in oysters is likely to be an important global mitigation strategy for sustainable shellfish aquaculture to withstand future climate‐driven change to habitat acidification.