Open Deep Water Research Articles

Biodiversity of Calanoida Copepoda in Different Habitats of the North-Western Red Sea (Hurghada Shelf)

Little is known about the diversity of Calanoida, Copepoda, in different habitats of the north-western Red Sea. In this study, biodiversity of Calanoida, Copepoda, during the cold and warm seasons of 2017, were observed at 12 stations belonging to four different habitats (coral reef (CR), sheltered shallow lagoons (SSL), seagrass (SG), and open deep-water (ODW) habitats) in the Hurghada shelf, north-western Red Sea. SSL habitats were the most affected by environmental conditions, especially temperature, salinity, and depth. Some calanoid species were restricted to certain habitats, others were adapted to live in more than one habitat, while some species showed a wide distribution in all habitats. ODW habitats showed maximum diversity and density of the calanoid species. The effects of temperature and salinity were distinct in the SG and SSL. The results clearly showed that different Red Sea habitats affected the biodiversity of calanoid copepods.

Decrement in Swimming Performance with Added Burden of Outer Clothing

Background: Most drowning occurs after an involuntary fall into open deep water. Thus, the victim is usually wearing outer clothing. The added burden of clothing may reduce the chance of survival. Methods: Grade Four children (n = 490) swam a 200 m combined test, twice, half with outer clothing first, half without. The test included jump or dive into deep water, swim 100 m on the front, stop and rest 3 min front and back, swim 100 m on the back and climb out over edge of pool. Each skill was scored from 0 to 2.0, a perfect score being 12.0. The Wilcoxen Signed Rank test was used to test the significance of the difference between treatments. Total scores with and without outer clothing were correlated using the Spearman rho. Results: The average total scores were 10.65 without outer clothing and 8.55 with (of 12.0). The Wilcoxen Z score was 2.79, statistically significant at p = 0.005. The Spearman rho between the two scores was 0.41. Of those who were judged able to swim without outer clothing, a significant number were judged unable to swim with outer clothing. This was true at whatever level “can swim” was arbitrarily placed. Among those who scored best, the difference between without and with clothing was considerably less than among those who scored poorly. Conclusions: The added burden of clothing significantly affected skill performance. It cannot be assumed that one who can swim without outer clothing, can swim with. The moderate correlation between scores suggests that economical movement may be the quality which transfers from without to with clothing.

Competition for basking places between the endangered European pond turtle (Emys orbicularis galloitalica) and the introduced red-eared slider (Trachemys scripta elegans)

Large numbers of red-eared sliders (Trachemys scripta elegans) have been imported into Europe for several years as part of the pet trade. These alien turtles have entered habitats where they interact with native pond turtles (Emys orbicularis). We investigated competition for basking sites, because optimal basking sites may be a restricted resource in the wild. We used experimental ponds to compare basking-place selection between single-species groups and mixed-species groups. Both species preferred basking places in open deep water. In mixed groups the sliders outcompeted the European turtles for preferred basking places. Although competition for basking places is only one component of resource partitioning between these two species, it provided an insight into the relationships between an introduced and a native species. Behavioural asymmetries like those detected in our experiments argue for the caution principle in the animal trade.