Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia

Oyster shells are substratum for different epibiontic and endobiontic organisms, including pests and parasites. Rocellaria dubia is endolithic and facultative tube-dwelling bivalve, boring in different calcareous substrates, including the shells of bivalves. In 2020, R. dubia was found as endolithic in the shells of the Pacific oyster Magalana gigas, from an oyster farm off the Sacca di Goro lagoon (Emilia-Romagna region, Northern Adriatic Sea, Italy). The purpose of this study was to describe this newly recorded association. Altogether, 136 specimens of R. dubia were found in 15 oysters, photographed under a stereoscope, and their length was measured. Heavily infested oysters hosted tens of R. dubia borers, which were perforating the whole thickness of the oyster valves. The flesh of these oysters was heavily damaged, suggesting parasitic association. R. dubia specimens were categorized into three age classes (0–1, 1–2, and 2–3 years old). M. gigas/R. dubia might be a widespread association, overlooked due to the very scarce research on macrofauna associated with M. gigas. Considering the negative effects of R. dubia endobiosis on oyster fitness, and possible impacts on oyster aquaculture, further research should be conducted in order to elucidate the distribution and ecological characteristics of this parasitic association.

Download Full-text

Dynamics of environmental conditions during the decline of a <i>Cymodocea nodosa</i> meadow

Biogeosciences ◽

10.5194/bg-17-3299-2020 ◽

2020 ◽

Vol 17 (12) ◽

pp. 3299-3315 ◽

Cited By ~ 1

Author(s):

Mirjana Najdek ◽

Marino Korlević ◽

Paolo Paliaga ◽

Marsej Markovski ◽

Ingrid Ivančić ◽

...

Keyword(s):

Environmental Conditions ◽

Light Availability ◽

Plant Performance ◽

Regular Growth ◽

Cymodocea Nodosa ◽

Negative Effects ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Light Reduction ◽

High Concentrations

Abstract. The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, the species successfully adapted to the changes in environmental conditions and prevented H2S accumulation by its reoxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 when light availability to the plant was drastically reduced due to increased seawater turbidity that resulted from increased terrigenous input, indicated by a decrease in salinity accompanied with a substantial increase in particulate matter concentration, combined with resuspension of sediment and elevated autotrophic biomass. Light reduction impaired photosynthesis of C. nodosa and the oxidation capability of belowground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of aboveground and belowground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation in the sediment and remainder of the belowground tissue. Our results indicate that if disturbances of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at a maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

Download Full-text

Dynamics of environmental conditions during a decline of a <i>Cymodocea nodosa</i> meadow

10.5194/bg-2019-484 ◽

2020 ◽

Author(s):

Mirjana Najdek ◽

Marino Korlević ◽

Paolo Paliaga ◽

Marsej Markovski ◽

Ingrid Ivančić ◽

...

Keyword(s):

Environmental Conditions ◽

Light Availability ◽

Plant Performance ◽

Regular Growth ◽

Cymodocea Nodosa ◽

Ground Tissue ◽

Negative Effects ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Below Ground

Abstract. The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, C. nodosa successfully adapted to the changes of environmental conditions and prevented H2S accumulation by its re-oxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 by a reduction of light availability which affected photosynthesis of C. nodosa and the oxidation capability of below-ground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of above- and below-ground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation and recovery of the below-ground tissue. Our results indicate that if disturbance of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

Download Full-text

Distribution patterns of two co-existing oyster species in the northern Adriatic Sea: The native European flat oyster Ostrea edulis and the non-native Pacific oyster Magallana gigas

Ecological Indicators ◽

10.1016/j.ecolind.2020.106233 ◽

2020 ◽

Vol 113 ◽

pp. 106233 ◽

Cited By ~ 2

Author(s):

Nika Stagličić ◽

Tanja Šegvić-Bubić ◽

Daria Ezgeta-Balić ◽

Dubravka Bojanić Varezić ◽

Leon Grubišić ◽

...

Keyword(s):

Adriatic Sea ◽

Pacific Oyster ◽

Distribution Patterns ◽

Ostrea Edulis ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Oyster Species ◽

Flat Oyster

Download Full-text

Reproductive cycle of a non-native oyster, Crassostrea gigas, in the Adriatic Sea

Mediterranean Marine Science ◽

10.12681/mms.21304 ◽

2020 ◽

Vol 21 (1) ◽

pp. 146 ◽

Cited By ~ 3

Author(s):

DARIA EZGETA BALIĆ ◽

IVANA RADONIĆ ◽

DUBRAVKA BOJANIĆ VAREZIĆ ◽

BARBARA ZORICA ◽

JASNA ARAPOV ◽

...

Keyword(s):

Reproductive Biology ◽

Reproductive Cycle ◽

Environmental Conditions ◽

Crassostrea Gigas ◽

Adriatic Sea ◽

Pacific Oyster ◽

Indigenous Species ◽

Natural Habitats ◽

Northern Adriatic ◽

The Pacific

The Pacific oyster Crassostrea gigas was introduced for the aquaculture purposes in many different parts of the world. However, the species has never been officially introduced for commercial farming in the Croatian part of the Adriatic Sea. Interestingly, in the 1970s, the Pacific oyster has been reported in the natural habitats of the Lim Bay, in northern Adriatic Sea. Although the species was recorded there, there is a lack of knowledge about its biology and ecology in this region, including a reproductive cycle. Information on the reproductive biology of non-indigenous species in new areas is crucial for prediction of their future survival and possible spread in invaded habitats. In this study, we provide the first data on the reproductive biology of the Pacific oyster in the Adriatic Sea, the northernmost part of the Mediterranean Sea. Quantitative and qualitative methods of gonad tissue analysis were conducted, and effects of environmental conditions on the gametogenesis were evaluated during two reproductive cycles. Our study confirmed that environmental conditions in the Lim Bay were favourable for the reproduction of the species. The Pacific oyster reproduced once per year and had a prolonged spawning period. Water temperature was the main factor affecting gonad development and oocyte size, while chlorophyll a concentration had an impact on the oocyte development in terms of their size.

Download Full-text

Growth and morphometric characteristics of the scallop Flexopecten glaber (Bivalvia: Pectinidae) reared in cages off the coast of Crimea (Black Sea)

Ruthenica, Russian Malacological Journal ◽

10.35885/ruthenica.2021.31(3).3 ◽

2021 ◽

Vol 31 (3) ◽

pp. 127-138

Author(s):

N. K. Revkov ◽

A. V. Pirkova ◽

V. A. Timofeev ◽

L. V. Ladygina ◽

S. V. Schurov

Keyword(s):

Pacific Oyster ◽

Live Weight ◽

Linear Size ◽

Weight Growth ◽

The Pacific ◽

Sevastopol Bay ◽

Length Range ◽

Oyster Farm ◽

Convexity Index ◽

Interval Type

The spat of the scallop Flexopecten glaber were collected in cages with the Pacific oyster Crassostrea gigas cultured on a mussel-and-oyster farm (outer roadstead of Sevastopol Bay). For two years they were reared in plastic cages at a depth of 2-3 m. The cages were periodically withdrawn to measure the size and weight parameters of the molluscs: the length (L, mm), height (H, mm), and width (D, mm) of shells and the total live weight (W, g). The correlations among the parameters under study are presented. The changes in the indices of the frontal (D/L) and sagittal (H/L) curvatures, convexity ((H+D)/L) and conditional volume (H×D×L/1000) of the shells in ontogenesis are shown. Upon reaching a shell length of 30-35 mm, the allometry of the volumetric and weight growth of molluscs changed from positive to negative. The largest values of the shell convexity index were registered in thesame length range. A conclusion about the interval-type growth of F. glaber in linear size and weight is made. It is suggested that the optimal strategy of shell formation in F. glaber in ontogenesis implies the ripening and the first reproduction of the molluscs occurring at the highest volumetric characteristics of the shell. The relationships for the linear size and weight growth ofF. glaber in the first two years of life are obtained. It is concluded that the scallop F. glaber should be considered as a possible element for the diversification of the existing aquaculture of molluscs (mussels and oysters) off the coast of Crimea.

Download Full-text