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Hoki (Macruronus novaezelandiae Hector) year class strength (YCS) varies substantially from year to year. We examined associations between YCS and climate variables including the Southern Oscillation Index (SOI), satellite sea surface temperatures (SSTs), synoptic weather patterns, wind speeds, and the depth of the west coast, South Island, New Zealand, mixed layer. We evaluated the predictions of a model developed 2 years ago to predict YCS of the western and eastern New Zealand hoki stocks from similar climate variables. New predictive models were developed using updated data. Strong year classes of the western hoki stock were associated with cooler SSTs, a negative SOI, and westerly or south‐westerly flow along the west coast of the South Island. We accordingly predict a moderately strong 1997 year class and weak 1998 and 1999 year classes for the western stock of hoki. The current model cannot predict eastern stock year class strengths with confidence.  相似文献   

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Don Maurer 《Marine Ecology》1983,4(3):263-274
Abstract. Animal-animal interactions are recognized as critical in benthic invertebrate recruitment. The hypothesis tested was that benthic recruitment is more successful in low densities of infaunal suspension feeders than in high densities. Densities of young hard clams Mercenaria mercenaria (L.) ranging from 82.5 to 330m-2 were placed in defaunated boxes of sand. The mean number of species, mean number of individuals, mean wet weight biomass, mean species richness and mean dominance index per sample were calculated per density of hard clams from May to October. The experiment did not support the hypothesis. It was concluded that feeding behaviour of dense populations of M. mercenaria did not preclude successful recruitment of other benthic species.  相似文献   

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1 Introduction M any estuarine and coastal copepods that havepreviously been classified as holoplankton m ightbestbe described as adultm eroplankton since they actuallyspend a portion oftheir life cycle in the seabed as rest-ing eggs [review ed by G rice and M arcus (1981) andM arcus (1996)]. R esting eggs can be extrem ely abun-dant (106 m ) in bays and estuaries especially w here -2w aterdepths are less than 20 m (M arcus,1989).Theyare likely to profoundly influence the dynam ics ofpel…  相似文献   

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Fish trapping experiments were carried out during 1973–75 along the north‐east coast of the North Island. The most effective trap type was the Z‐trap. Two sizes of Z‐trap were tested. Better results were obtained with the larger ones, which had an overall mean catch rate of 8.4 fish/trap day. The catch rate varied widely between areas, bottom types, and seasons. Best results were obtained in summer in depths greater than 20 m.  相似文献   

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We investigated sources of inter-annual variability in larval supply to crab and sea urchin populations at Bodega Head and Point Reyes in northern California. During the spring and summer upwelling seasons of the years 1992 through 1997 we monitored the weekly settlement rates of nine species of crabs and two species of sea urchins. As observed in previous studies, daily values of alongshore windstress, temperature and salinity provided evidence for the poleward flow of relatively warm, low salinity water from south of Point Reyes, an apparent retention zone, during upwelling relaxation events. In years dominated by these events (1992, 1993, 1995 and 1996) we observed that alongshore windstress, temperature and salinity were coherent and temperature was significantly correlated with cancrid crab settlement. During these years the magnitude of cancrid crab settlement and the fraction of cancrid crabs relative to other crab species settling were high. Over four years of concurrent sampling there was consistently greater cancrid crab settlement at the Point Reyes site, within the retention zone, than at Bodega Head. Settlement of non-cancrid crabs (porcellanids, grapsids, pagurids and majids) was not as closely linked to intra-annual patterns of upwelling and relaxation, possibly due to the shorter seasonal availability of larvae allowing for the influence of fewer relaxation events. Settlement of this group among years was positively correlated with environmental indicators of strong seasonal upwelling; high salinity, Bakun upwelling index and low temperature. Sea urchin settlement events were observed in June and July of 1992, 1994 and 1997 during warming periods when salinity and temperature were increasing and alongshore windstress was low. Across the six years of the study, we found that cancrid crab larvae had a more even seasonal availability than larvae of non-cancrid species, which settled in greatest numbers during the early portion of the upwelling season. Sea urchins settled in greatest numbers during the later part of the upwelling season. Together these patterns demonstrate the taxon-specific way that inter-annual variability in larval supply is forced by the coincidence of larval availability with favorable physical transport mechanisms.  相似文献   

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