Chapter 5 – PELECYPODA (EXCLUDING OSTREIDAE)

Crassostrea gigas (Thunberg) and Ostrea edulis L. were grown at sustained temperatures
 of 12°, 15°, 18° and 21°C for a period of 19 weeks. Regular assays of weight specific ammonia excretion rate were made, following which animals were sacrificed for estimation of dry meat weight, dry shell weight, biochemical composition (percentage carbon, nitrogen, carbohydrate, ash) and gonadal development (histological assessment). Crassostrea gigas grew from an intial live weight of 5·2 g to values of 23·5, 28·2, 34·6 and 38·7 g at 120, 150, 180 and 21 °C respectively.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315400046208

Some biochemical and physiological aspects of growth and gametogenesis in Crassostrea gigas and Ostrea edulis grown at sustained elevated temperatures.

The bivalves Spisula solidissima, the Atlantic surf clam, and Arctica islandica, the ocean quahog, from the continental shelf off New Jersey, contain repeating structures in their shells. By ana- lyzing the growing shell margins in living specimens at bi-weekly (or sometimes monthly) intervals throughout two consecutive years, it was possible to define an annual cycle of shell growth increment formation in both species. The shell increments in each species are microstructurally distinct units that form over a period of several months at select seasons of the year. Each species has two alternating shell growth increments, GI I and GI I. GI I (the annual growth line of previous studies) is formed annually in the late summer-fall in S. solidissima and in the fall-early winter in A. islandica. These periods correspond to the spawning phase of the reproductive cycle in both species. No winter rings were found. The annual increments were used to determine age and growth rate in both Recent and Pleistocene specimens. They may also be useful in determining season of death. Because shell growth increments are formed in synchrony among living populations in these species, mass mortalities may be distinguished in the fossil record. Accurate age and growth rate determinations in fossils are important in many paleobiologic contexts, such as deciding between increased longevity or growth rate in cases of phyletic size increase.

Annual cycle of shell growth increment formation in two continental shelf bivalves and its paleoecologic significance

Reproductive strategy of the freshwater pearl mussel Margaritifera margaritifera

The importance of the extensive intertidal mud-flats to the energy budget of estuaries has frequently been stressed, but seldom quantified. Smidt (1951) has discussed the production of both macro- and meiofauna from the Danish Waddens in general terms but, because of the wide coverage, his information is not detailed enough to quantify annual production in terms of g/m2. The present study was designed to compare the productive importance of macrofauna and meiofauna in detail at a single site. This paper deals only with the first phase of this study, the macrofauna, which are retained on a 0.5 mm sieve for the major part of their productive life.

/pdf/macrofauna-production-in-an-estuarine-mud-flat-cs1cih0fo3.pdf

Macrofauna production in an estuarine mud-flat

1. A biannual reproductive cycle was observed in Spisula solidissima gonads during 3 of the 4 years in which samples were taken from offshore New Jersey. 2. The biannual cycle was characterized by a major mid-year spawning and minor late-year spawning. A second annual reproductive cycle may be neither typical for surf clams throughout their geographical range nor always an annual event in clams from New Jersey. 3. A delayed spawning and single annual cycle in 1965 was related to colder environmental temperatures than were observed in the three earlier years of the study. 4. Abrupt temperature changes were not clearly a cause of spawning in the natural populations of surf clams. Partially spawned clams were found in the samples in advance of abrupt temperature changes. Temperature, however, clearly delays or hastens the gametogenic cycle and stimulates spawning of ripe surf clams in the laboratory.

Reproductive cycle of the surf clam, spisula solidissima, in offshore new jersey

1. Only a single reproductive cycle was observed in Mya arenaria gonads collected from areas north of Cape Cod.2. In eastern Maine, the spawning season extended from early June to the middle of August. Boothbay Harbor clams spawned from late June to late August. Clams from Plum Island Sound began spawning in July, a month later than eastern Maine clams, and completed spawning by late September.3. Observations of gonadal changes in Mya from southern Cape Cod indicated a biannual cycle occurs. These observations are supported by previous reports of spawning activities, larval occurrence, and gametogenesis in Mya from the southern latitudes.

John W. Ropes

Papers

Reproductive cycle of the surf clam, spisula solidissima, in offshore new jersey

Reproductive cycle of mya arenaria in new england