On the behaviour of barnacle. IV. The influence of temperature on cirral activity and survival of some warm water species

On the behaviour of barnacle. IV. The influence of temperature on cirral activity and survival of some warm water species

352 Oceanographic Abstracts 2. In the Pwllheli area it was found that eggs were laid during the second half of August ant~ were hatched between mid-...

103KB Sizes 1 Downloads 11 Views

352

Oceanographic Abstracts

2. In the Pwllheli area it was found that eggs were laid during the second half of August ant~ were hatched between mid-June and mid-July. There is evidence o f some variation from year re. year and at different points along the Welsh coast. 3. The data available indicate that in 1955 the majority of males and immature females moulted between mid-May and mid-June, unlike the mature females which moulted about 6 weeks later. 4. It was found that off Pwllheli the females became mature over the size range of 8-7 to Io ~inches total length (77 to 97 mm carapace length) and that off Anglesey the size at first maturil~ ~:~ greater, i.e. 9.5 to 11'6 inches total length (85 to 104 mm carapace length). 5. The relatively small migrations o f lobsters observed in other places were found to apply ,~: the Pwllheli area. 6. Problems arising in the determination of total and fishing mortalities are discussed. 7. Measurements of over 400 lobsters are used to calculate the equations o f the regressior,o f total length on carapace length, of carapace length on total length and of weight on carapace length, for the sexes separately. 8. A comparison between the length of lobsters of approximately the minimum legal size ~i 9 inches on their fronts and backs showed a difference of just under ¼ inch.

SNODGRASS,J. M., 1962. Long-range outlook for oceanographic telemetering. 31ar S~i. lnstrute

lnstrum. Soc., Amer., Plenum Press, N.Y., 1 : 163-167. With expanding oceanographic research programs, communications promise to be a troublesome problem. Existing frequencies in the radio communications spectrum are almost completely ab~ sorbed by military, commercial and amateur interests. New means must be devised to communicate, with research and survey ships. Circuits which will permit large amounts of data to be transmitte~ with high accuracy are needed. Data telemetering over vast ocean areas will require many new techniques since present practice in the missile and flight test field is limited to line of sight. Conflicts with ocean missile ranges wilt need to be resolved, as well as devising suitable international agreements to permit long-range telemetering and the establishment of unattended deep-sea buoys and instrument stations. Telemetering over ranges o f several thousands of miles is necessary from unmanned floating instrument stations. Proposed communications types of satellites offer promising possibilities.

SOROKIN,Y. 1., 1962. Experimental study of bacterial sulphate reduction in the Black Sea using S 35. (In" Russian). Mikrobiologiia, 31 (3): 402-410. Sulphate reduction ~s most intensive in the superlicial layer of the bottom sediments in the peri~ pheral regions o f the sea, and on the continental slope. On the interface of the chalistatic region~, the rate of sulphate reduction is also appreciable. In the central parts o f the sea sulphate reduction in the superficial layer of the bottom decreases many times. Within the ground active sulphate reduction occurs in a ca. 5 cm thick layer. Evidence has been obtained to the effect that within tbc sludge sulphate reducing bacteria are absent. In the water mass sulphate reduction was detected in the upper part of the hydrogen sulphide zone, and in lesser amounts in the benthonic layer, SOUTHWARD, A. J., 1962. On the behaviour of barnacles. IV. The influence of temperature on cirral activity and survival of some warm water species. J. Mar. Biol. Ass., U.K., 42 ~2) : 163- 178. The range o f temperatures over which the cirri were active and the frequency of beating at differe~i temperatures were measured in four species of barnacles collected on the southern and south-western coasts o f France. The extremes of high temperature at which the animal remained irritable or could survive were assessed in these species and in a further group of species from Trinidad, West Indies. The results are discussed in comparison with previous evidence for species o f more northerr~ distribution, and related to the geographical range o f the species and the ecological niche occupied, For example, the brackish water species, Balanus eburneus and B. improvisus, have similar patterns o f cirral activity, but the greater tolerance of high temperatures shown by the former is obviously connected with its more tropical distribution. Differences in temperature tolerances o f varieties of B. amphitrite from Europe and Trinidad, possibly related to differences in the tide levels at which they live, tend to reinforce their separation on morphological grounds. More pronounced differences between Chthamalus depressus and C. stellatus confirm the separation o f these two species which were formerly regarded as varieties. The relatively lower rate o f beating of C. d~pressus which is not found north o f the Mediterranean and its greater tolerance of high temperatures compared with C. stellatus, may be related to its more southern distribution and its ability to live at very high levels on the shore. These two species and C. fragilis from Trinidad all show greater tolerance of high temperatures that the species of Batanus and Tetraclita, which are found at lower levels on the shore It is concluded that in the North Atlantic area there may be only two main distributional groups of species o f acorn barnacles, Arctic and Tropical, overlapping in the Temperate regions, with few or no intermediate forms, and that there is as yet no evidence for the existence of physiological races in these species.