Abundance and Taxa Composition of Copepod Nauplii Over Southeastern Bering Sea Deep Water Spawning Grounds of Walleye Pollock, Theragra ChalcogrammaPaul, A.J.; Paul, J.M.; Coyle, K.O.
doi: 10.1163/156854096x01078pmid: N/A
AbstractThis project examined the abundance, taxa, stage and size of copepod nauplii available as prey for walleye pollock larvae in its deep water spawning grounds of the southeastern Bering Sea. Nauplii of the genera Oithona, Eucalanus, and Metridia were the most commonly encounted types while Pseudocalanus and Microcalanus were rare. There was marked interannual variation in the taxa and abundance of copepod nauplii coexisting with the pollock larvae. Stages I-IV of Oithona were present at 0 to 8 l-1 at different depths. Individual stages III-VI of Metridia nauplii occurred at 0 to 6 l-1, while Eucalanus nauplii were present at 0.1 to 9 l-1, depending on stage and depth. Nauplii III-IV of the genera Pseudocalanus and III-VI Microcalanus were usually present at less than 1 l-1. In 1992, 54 to 56% of the nauplii had body lengths of 150-350 μm which are typical of those found in stomachs of first-feeding pollock larvae. In 1993 corresponding estimates were 64 to 68%. Copepod nauplii with body lengths of 150-350 μm were generally present at 1 to 15 l-1, but at one station their counts exceeded 20 l-1.
Total Haemocyte Counts and Haematopoiesis in Saduria Entomon (Linnaeus, 1758) (Isopoda, Valvifera) From the Baltic Sea Infected With the Yeast Cryptococcus La Urentii (Kufferath) Skinner*)Babula, A.; Hryniewiecka-Szyfter, Z.
doi: 10.1163/156854096X01069pmid: N/A
<jats:sec><jats:title>Abstract</jats:title><jats:p>Studies were made of the haemolymph and haematopoiesis of 22 specimens of Saduria entomon, naturally infected with the yeast Cryptococcus laurentii. In 18 of these haemocytes were also counted. Their total haemocyte count was 693, which is 3 times the figure in healthy S. entomon. Their haemolymph contained granulocytes, hyaline cells, and C. laurentii cells. Granulocytes contained phagocytosed C. laurentii cells, while hyaline cells did not contain phagocytosed yeast. Haematopoiesis was clearly taking place in the gut wall of the S. entomon specimens under study. In the 4 remaining individuals the haemolymph was filled with C. laurentii cells among which only single hyaline cells with phagocytosed yeast cells were observed. In their gut wall only yeast cells accumulated. The results obtained support our earlier findings that in S. entomon granulocytes are the primary phagocytotic haemocytes, and that hyaline cells can be taken to be prohaemocytes capable of proliferation under specific conditions.</jats:p>
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Burrowing Behaviour and Cost in the Sandy-Beach Oniscid Isopod Tylos Granulatus Krauss, 1843Brown, A.C.; Trueman, E.R.
doi: 10.1163/156854096X01014pmid: N/A
<jats:sec><jats:title>Abstract</jats:title><jats:p>Tylos granulatus is an isopod living above the driftline on sandy shores, burrowing to depths of up to a metre or more. Burrowing has been investigated by analyzing video recordings and traces from isotonic and isometric transducers. In crawling, all seven pairs of pereiopods operate in a similar manner and display metachronal rhythm, while in burrowing pereiopods 1 to 3 do the digging, pairs 4 to 6 compact the excavated sand, and pair 7 pushes the bolus behind the animal. Movements of the head also play a significant role in burrowing. Clockwise or anticlockwise partial rotation occurs during burrowing, which takes place in a stepwise progression. With a Burrowing Rate Index of 3, the animal must be considered a powerful burrower, while the energy cost of burrowing is surprisingly low at some 0.3 J m-1.</jats:p>
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Total Haemocyte Counts and Haematopoiesis in Saduria Entomon (Linnaeus, 1758) (Isopoda, Valvifera) From the Baltic Sea Infected With the Yeast Cryptococcus La Urentii (Kufferath) Skinner*)Hryniewiecka-Szyfter, Z.; Babula, A.
doi: 10.1163/156854096x01069pmid: N/A
AbstractStudies were made of the haemolymph and haematopoiesis of 22 specimens of Saduria entomon, naturally infected with the yeast Cryptococcus laurentii. In 18 of these haemocytes were also counted. Their total haemocyte count was 693, which is 3 times the figure in healthy S. entomon. Their haemolymph contained granulocytes, hyaline cells, and C. laurentii cells. Granulocytes contained phagocytosed C. laurentii cells, while hyaline cells did not contain phagocytosed yeast. Haematopoiesis was clearly taking place in the gut wall of the S. entomon specimens under study. In the 4 remaining individuals the haemolymph was filled with C. laurentii cells among which only single hyaline cells with phagocytosed yeast cells were observed. In their gut wall only yeast cells accumulated. The results obtained support our earlier findings that in S. entomon granulocytes are the primary phagocytotic haemocytes, and that hyaline cells can be taken to be prohaemocytes capable of proliferation under specific conditions.