Urofaecal glucocorticoid metabolite concentrations in African penguin (Spheniscus demersus) chick populations experiencing different levels of human disturbance

This is the final version. Available on open access from Oxford University Press via the DOI in this recordDespite the importance of ecotourism in species conservation, little is known about the industry’s effects on wildlife. In South Africa, some African penguin (Spheniscus demersus) colonies have become tourist attractions. The species is globally endangered, with population sizes decreasing over the past 40 years. As African penguin chicks are altricial and unable to move away from anthropogenic stressors, it is important to evaluate the effect of tourist activities on baseline glucocorticoid levels as a measure of potential disturbance. Chicks at three study sites within two breeding colonies (Robben Island, Stony Point), with varying levels of exposure to tourism (low/moderate/high) were monitored. Urofaecal samples were collected to determine urofaecal glucocorticoid metabolite (ufGCM) concentrations as an indication of baseline stress physiology. Morphometric measurements were taken to compare body condition between sites. Penguin chicks experiencing low, infrequent human presence had significantly higher mean (± standard deviation) ufGCM levels [1.34 ± 1.70 μg/g dry weight (DW)] compared to chicks experiencing both medium (0.50 ± 0.40 μg/g DW, P = 0.001) and high levels of human presence (0.57 ± 0.47 μg/g DW, P = 0.003). There was no difference in chick body condition across sites. These results suggest that exposure to frequent human activity may induce habituation/desensitization in African penguin chicks. Acute, infrequent human presence was likely an important driver for comparatively higher ufGCM levels in chicks, though several other environmental stressors may also play an important role in driving adrenocortical activity. Nevertheless, as unhabituated chicks experiencing infrequent anthropogenic presence showed significantly higher ufGCM levels, managers and legislation should attempt to minimize all forms of activity around important breeding colonies that are not already exposed to regular tourism. Although the results of this study are crucial for developing enhanced conservation and management protocols, additional research on the long-term effect of anthropogenic activities on African penguin physiology is required.Department of Biodiversity and Conservation Biology at the University of the Western CapeSouth African National Research FoundationEarthwatch Institut

Sublittoral seaweed communities on natural and artificial substrata in a high-latitude coral community in South Africa

Coral mortality may result in macroalgal proliferation or a phase shift into an alga dominated state. Subtidal, high-latitude western Indian Ocean coral communities at Sodwana Bay on the KwaZulu-Natal coast, South Africa, have experienced some mortality because of warm water anomalies, storms and other causes, but the response of the macroalgae is unknown. We investigated the abundance and diversity of benthic algae on different hard natural substrata (dead digitate, brain and plate corals and beach rock) on Two-Mile Reef, Sodwana Bay. We also compared algal communities colonising ceramic, marble and pretreated ceramic tiles placed on the reef for six months. We identified 95 algae (14 Chlorophyta, 11 Phaeophyceae, 69 Rhodophyta and one cyanobacterium). Assemblages on natural and artificial substrata were dominated by the brown alga Lobophora variegata (Lamouroux) Womersley ex Oliveira and non-geniculate corallines (Rhodophyta, Corallinaceae). Cluster and ordination analyses revealed that the algae showed no affinity for particular substrata, whether natural or artificial. Algal cover was occasionally higher on rougher tiles and crustose corallines were significantly more abundant on marble than ceramic tiles. Two-Mile Reef had 23.1% dead and 48.4% live scleractinian coral cover, where dead corals were colonised indiscriminately by many small algal species, but there was no evidence of algal proliferation. The results provide a baseline for monitoring this high-latitude reef system.DHE

Short CommunicationGrowth of post-weaning abalone Haliotis midae fed commercially available formulated feeds supplemented with fresh wild seaweed

The effect of five formulated feeds supplemented with fresh wild seaweed on the growth of post-weaning juvenile abalone Haliotis midae (6–20 mm shell length) was investigated by means of a growth trial at a commercial abalone farm over a period of 11 months. The experiment included 10 diet treatments with two replicates each (n = 50 individuals per replicate). The first five diet treatments comprised four fishmealbased formulated feeds: Abfeed®, Adam & Amos® ‘a', Adam & Amos® ‘b' and Adam & Amos® ‘c'; and an all-seaweed-based formulated pellet, FeedX. The additional five diet treatments comprised the formulated feeds above, supplemented with fresh wild seaweeds: the kelp Ecklonia maxima (5–15% protein) and Ulva lactuca (3.7–19.9% protein). The fishmeal-based protein feeds produced significantly better growth than the all-seaweed-based protein feed (FeedX: 0.49 ± 0.03 specific growth rate [SGR]; 27.15 ± 0.02 daily increment increase in shell length [DISL]; 0.864 final condition factor [CF]). Abfeed® (1.00 ± 0.02 SGR; 60.79 ± 0.04 DISL; 1.312 final CF) performed best of all the formulated feeds. Supplementation with fresh, wild seaweed, however, significantly improved growth of all abalone with supplemented Abfeed® (1.05 ± 0.02 SGR; 63.61 ± 0.05 DISL; 1.447 final CF), outperforming all supplemented feeds. A noteworthy observation was that the condition factor of abalone fed the feed that performed particularly poorly in the growth trials (FeedX) was dramatically improved by supplementation. It was shown that supplementation with fresh wild seaweed enhances the growth of abalone reared on formulated feeds.Keywords: Abfeed®; Adam & Amos®; diet; formulated feed; growth; Haliotis midae; seaweed; supplementationAfrican Journal of Marine Science 2008, 30(1): 199–20