POPULATION DYNAMICS OF THE WANDERING ALBATROSS DIOMEDEA EXULANS AT MARION ISLAND: LONGLINE FISHING AND ENVIRONMENTAL INFLUENCES

The subantarctic Prince Edward Islands (Marion and Prince Edward) support the largest breeding population of the Vulnerable wandering albatross Diomedea exulans. The number of birds breeding at Marion Island has fluctuated over the past three decades apparently as a result of both real changes in the size of the population and changes in the proportion of the population that attempts to breed in a given year. Changes in several demographic parameters that appear to be influenced by both environmental and anthropogenic effects are described. From 1994–2001, the proportion of first-time breeders in the population was positively correlated with the maximum ENSO (Ni&#241o 3) index, whereas from 1984–2000 the annual survival rates of breeding adults were negatively correlated with Japanese pelagic longline fishing effort in the southern Indian Ocean. Adult survival rates were significantly correlated with those on neighbouring Possession Island, Crozet Islands, but differed from those at South Georgia, suggesting common factors operating at an ocean-basin scale. The average survival rate of adult females was lower than that of males. Males who lost partners took 40% longer than females to find a new mate, suggesting a male-biased population. Survival rates of juvenile males and females did not differ. The age distribution of first-time breeders shifted progressively towards younger birds during the 1990s. Higher than expected survival rates of breeding adults during the late 1990s may be linked to large amounts of supplementary food being made available by the initiation of a longline fishery for Patagonian toothfish Dissostichus eleginoides close to the islands at this time. Overall, breeding success was better than recorded at other localities, indicating that breeding conditions at Marion Island were comparatively favourable. The early implementation of both international and national conservation initiatives to reduce the impact of longline fishing on this species and improve its conservation status is encouraged.Afr. J. mar. Sci. 25: 503–51

UNUSUAL BREEDING BY SEABIRDS AT MARION ISLAND DURING 1997/98

In 1997/98, breeding at subantarctic Marion Island was exceptionally good for five species of seabirds capable of foraging over wide areas and for a tern. The number of king penguin Aptenodytes patagonicus chicks surviving to the start of spring in 1997 was considerably more than previously recorded. Greater numbers of wandering Diomedea exulans and grey-headed Thalassarche chrysostoma albatrosses, northern giant petrels Macronectes halli and Kerguelen terns Sterna virgata bred than previously recorded, and more southern giant petrels M. giganteus did so than in any other year since 1994. For southern giant petrels, reproductive success was higher than in any other year, as was survival of chicks of northern giant petrels. Conversely, for two seabirds that feed close to the island, gentoo penguin Pygoscelis papua and Crozet shag Phalacrocorax [atriceps] melanogenis, 1997/98 was a particularly poor breeding season. Gentoo penguins initiated breeding later than usual and fledged few chicks. The number of Crozet shags that bred decreased; probably about 25% of the adult population did not breed. For two species with an intermediate foraging range that eat mainly crustaceans, macaroni Eudyptes chrysolophus and eastern rockhopper E. chrysocome filholi penguins, breeding was not noticeably different from normal except that chicks of rockhopper penguins fledged with a slightly heavier mass than in other years. However, for both these penguins, the mass of adults on arrival at colonies decreased substantially in the following (1998/99) breeding season. The unusual breeding by most of the seabirds coincided with the El Niño Southern Oscillation (ENSO) event of 1997/98. This synchrony contrasts with lagged responses to ENSO events of seabirds that breed farther south in the Southern Ocean. Continued monitoring of seabirds over well-separated sites in the Southern Ocean may elucidate how climatic perturbations operating at a global scale impact seabirds in the region.Afr. J. mar. Sci. 25: 453–46

DECREASE IN NUMBERS OF THE EASTERN ROCKHOPPER PENGUIN EUDYPTES CHRYSOCOME FILHOLI AT MARION ISLAND, 1994/95–2002/03

The number of eastern rockhopper penguins Eudyptes chrysocome filholi breeding at subantarctic Marion Island decreased from about 173 000 pairs in 1994/95 to about 67 000 pairs in 2001/02. During 1994/95–2002/03 pairs fledged on average 0.40 chicks per year, an amount thought insufficient to balance mortality of breeding adults, and there was a decrease in the mass at arrival at breeding colonies of both males and females. Except in 1997/98, the mass of chicks at fledging was less than that recorded at two other localities. These factors suggest an inadequate supply of food for rockhopper penguins at Marion Island. Decreases of rockhopper penguins at several other localities also have been attributed to inadequate food. Rockhopper penguins at Marion Island continued to feed mainly on crustaceans during chick rearing. There was a marked increase in the contribution of fish to the diet in 1999/00 that coincided with an increase in mass at arrival at colonies of both males and females. Trends in numbers of pairs breeding in different sections of Marion Island were not always consistent, indicating the need for island-wide monitoring to establish the overall trend. Afr. J. mar. Sci. 25: 487–49

Ouditkunde 200

Exam paper for second semeste

Auditing 200

Exam paper for second semeste

Smoking and drinking habits of women in subsequent pregnancies after specific advice about the dangers of these exposures during pregnancy

Background. Although women are informed about the dangers of drinking and smoking during pregnancy when they book for antenatal care, it is uncertain whether this advice is accepted, or whether attempts are made to apply it in subsequent pregnancies.Objectives. To assess how pregnant women respond to the advice to refrain from smoking and drinking during pregnancy in subsequent pregnancies.Methods. Research staff were trained to obtain accurate prospective information on smoking and drinking during pregnancy in a prospective study, using well-standardised methods. Care was taken to inform participants about the dangers of smoking and drinking during pregnancy. They were also given pamphlets on these dangers in their own language and a list of telephone numbers where they could find help to quit should they need it. This information was repeated at subsequent study visits (ranging from 1 to 3, depending on the gestational age at which they enrolled). Gestational age was determined by early ultrasound. Z-scores of birthweight for gestational age were determined according to the INTERGROWTH-21st study. Pregnancy outcomes of women who enrolled twice (n=888) or three times (n=77) in the Safe Passage Study were compared with those of women in the first enrolment (n=889).Results. The proportion of drinkers did not change significantly (p=0.058) from the first to the second and third enrolments (63.8%, 59.0% and 54.6%, respectively). A similar trend was found for smokers (73.3%, 72.2% and 68.4%, respectively). Cannabis use was reported by 15.1%, 9.7% and 12.0% (p<0.005) of women, respectively, and use of methamphetamine by 10.1%, 6.6% and 12.7% (p<0.005). There was an increase in the rate of preterm births from 15.5% to 17.5% and 24.7%, respectively, but the increase was not significant. Although mean birthweight was lower in the third enrolment compared with the second, the difference was not significant. The z-score of birthweight for gestational age was significantly lower in the second enrolment compared with the first.Conclusions. Detailed information on the adverse effects of smoking and drinking during pregnancy was not effective in the population studied. Other methods to reduce or stop these toxic exposures should therefore be investigated. A short inter-pregnancy interval, as demonstrated by three enrolments in 7.5 years, is associated with preterm labour and fetal growth restriction, and is probably indicative of the role played by confounders such as poor socioeconomic conditions and drug exposure during pregnancy

POPULATION AND BREEDING OF THE GENTOO PENGUIN PYGOSCELIS PAPUA AT MARION ISLAND, 1994/95–2002/03

The numbers of gentoo penguins Pygoscelis papua breeding at subantarctic Marion Island fell by 40&#37 from 1994/95 to 2002/03, from 1 352 pairs to 806 pairs. Apart from a slight increase in 1998/99, there was a steady decrease in numbers breeding between 1995/96 and 2000/01, when the population stabilized. There is indication that in some years not all breeders nested and that some birds relocated to another colony after disturbance. From first clutches, pairs on average fledged between 0.01 chicks in 1997/98 and 0.58 chicks in 2002/03 (mean 0.38 &#177 0.21). In 1994/95, replacement clutches increased the overall production of fledged chicks by 11&#37. Based on demographic parameters measured at other localities, the production of chicks at Marion Island was inadequate to maintain the population during the period 1995/96–2000/01. Consistency in trends in breeding success at five colonies suggests that factors operating at a mesoscale, rather than those specific to particular colonies, often influenced breeding success. Laying was later than normal in 1997/98, when there was almost total breeding failure with large losses of eggs and small chicks to returning Subantarctic skuas Catharacta antarctica. Future research on this Near Threatened species at Marion Island must take full account of its susceptibility to human disturbance.Afr. J. mar. Sci. 25: 463–47