See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/265209025 Effect of habitat characteristics on the distribution and abundance of damselfish within a Red Sea reef Article in Environmental Biology of Fishes · December 2013 DOI: 10.1007/s10641-013-0212-9 CITATIONS READS 9 524 4 authors: Lauren Nadler Deborah C Mcneill Nova Southeastern University University of Glasgow 42 PUBLICATIONS 263 CITATIONS 14 PUBLICATIONS 41 CITATIONS SEE PROFILE SEE PROFILE Magdy Alwany David Mark Bailey Suez Canal University University of Glasgow 8 PUBLICATIONS 65 CITATIONS 122 PUBLICATIONS 2,698 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Exploring the role of coastal environments for gadoid fish using stereo-video imagery View project Stingrays in Mozambique View project All content following this page was uploaded by Lauren Nadler on 02 September 2014. The user has requested enhancement of the downloaded file. Environ Biol Fish DOI 10.1007/s10641-013-0212-9 Effect of habitat characteristics on the distribution and abundance of damselfish within a Red Sea reef Lauren E. Nadler & Deborah C. McNeill & Magdy A. Alwany & David M. Bailey Received: 17 April 2013 /Accepted: 27 November 2013 # Springer Science+Business Media Dordrecht 2013 Abstract For coral reef fish with an obligate relationship in patchy reef habitats than in continuous sections of the to their habitat, like Pomacentrid damselfish, choosing a reef, probably because average coral colony size was suitable home amongst the reef structure is key to sur- greater in patchy reef type. Fish group size increased vival. A surprisingly small number of studies have ex- significantly with coral colony volume and with larger amined patterns in adult damselfish distributions com- branch spacing. Multi-species groups of fish commonly pared to other ontogenetic phases. The aim of this study occurred and were increasingly likely with reduced was to determine which reef and coral colony character- branching density and increased coral size. istics explained adult damselfish distribution patterns in a Red Sea reef. The characteristics investigated were reef Keywords Coral reefs . Acropora spp . Chromis spp . type (continuous or patchy), coral species (seven species Dascyllus spp . Gulf of Aqaba of Acropora), and coral morphology (coral size and branching density). The focal damselfish species were Dascyllus aruanus, D. marginatus, Chromis viridis,and Introduction C. flavaxilla. Occupancy (presence or absence of resident damselfish), group size and fish species richness were not For coral reef fish with an obligate relationship to their significantly different between the seven Acropora spe- habitat, choosing an appropriate home amongst the reef cies. However, within each coral species, damselfish structure is key to avoiding predation, maximizing were more likely to occupy larger coral colonies than growth rate and finding mates (Booth and Wellington smaller coral colonies. Occupancy rates were also higher 1998; Martinez and Marschall 1999; Coker et al. 2009). Many Pomacentrid damselfish species exhibit strong site fidelity to a single coral colony, rarely venturing L. E. Nadler (*) : D. C. McNeill : D. M. Bailey Institute of Biodiversity, Animal Health and Comparative more than one meter away (Sale 1971; Sackley and Medicine, University of Glasgow, University Avenue, Kaufman 1996). Spatial distribution and abundance of Glasgow G12 8QQ, UK damselfish species are known to result from both larval e-mail: [email protected] recruitment (e.g. Booth and Wellington 1998; Booth M. A. Alwany 2002;Ben-Tzvietal.2008) and subsequent post- Department of Marine Science, Faculty of Science, Suez settlement movement during other ontogenetic phases Canal University, 41522 Ismailia, Egypt (e.g. Frederick 1997; Simpson et al. 2008; Coker et al. 2012); yet, surprisingly few studies have examined dis- Present Address: L. E. Nadler tribution patterns in adult damselfish compared to the School of Marine and Tropical Biology, James Cook larval and juvenile developmental stages (Bay et al. University, Townsville, QLD 4811, Australia 2001;Belmakeretal.2009; Ben-Tzvi et al. 2009). Environ Biol Fish Damselfish group size represents a trade-off between This study aims to describe adult damselfish distri- survival and growth rate. Larger group sizes decrease bution patterns in a Red Sea reef in the southern Gulf of individuals’ chances of predation (Sackley and Kaufman Aqaba. Though the Red Sea is known as a coral reef 1996) but increase competition for food (Kent et al. 2006). biodiversity hotspot with unique attributes such as var- These groups can be composed of one or more species, iable conditions and prevalent endemism, there are far even when food and energy requirements overlap fewer ecological studies in this region than other well- (Shpigel 1982; Shpigel and Fishelson 1986). However, known systems such as those in the Great Barrier Reef the habitat characteristics that promote larger group sizes and Caribbean (Berumen et al. 2013). The objective of and higher species abundance are still unclear. Sale this work was to fill knowledge gaps on which reef (1972a) found that increased coral size helped to mitigate types and coral morphologies promote adult damselfish agonistic interactions in damselfish groups, indicating that residency within seven Acropora spp. certain habitat morphologies may facilitate co-habitation. Previous studies have qualitatively examined the effect of branching morphology on damselfish occupancy and Material and methods found that the proportion of corals inhabited was higher in coral species with a less dense morphology (Booth 1992; Study site Bergman et al. 2000; Nanami and Nishihira 2005; Holbrook et al. 2000, 2008; Noonan et al. 2012). How- This study was implemented in Dahab, Egypt, in the Gulf ever, no quantitative comparisons between branch density of Aqaba (~28.49° N, 34.50° E) between May and July and damselfish group size have been performed. 2011 (Fig. 1). The Gulf of Aqaba is 180 km long and varies Though damselfish species have been found to asso- from 6 to 26 km wide. It is connected to the rest of the Red ciate with particular branching coral species, studies to Sea at the Straits of Tiran (Monismith and Genin 2004). date have examined these damselfish preferences in Two adjacent sites were sampled: Suleiman Reef and terms of confamilial groups of coral species that often the Islands. Suleiman Reef is a 200 m wide reef flat, exhibit highy divergent morphologies (e.g. Sale 1972a; dropping off at the reef crest into a continuous reef slope Fishelson et al. 1974; Shpigel and Fishelson 1986;Kent that reaches a sandy bottom at approximately 11–12 m et al. 2006). Whether closely related, congeneric coral deep. Seaward of the reef slope, there are a number of species would lead to similar adult damselfish-coral patch reefs surrounded by sand, at 12–15 m depth. species associations is still unclear. Bonin’s(2012)stud- The Islands site is more complex. Seaward of the ies of recently settled juveniles showed some damselfish fringing reef are the Islands themselves: two areas of species associating almost exclusively with a single reef that emerge at low water. The Islands are joined to Acropora spp. while others exhibited little preference. the fringing reef by large subtidal coral boulders be- Whether any species-specific coral preferences would tween which are sandy “pools”. Two pools within the carry over to the adult stage is unknown, as juveniles Islands site were surveyed. The first pool drops off at the have previously been shown to have more specialized reef crest into a continuous reef slope that reaches a habitat requirements than adults (Wilson et al. 2008). sandy bottom at approximately 9–11 m deep. Within Isolated (patchy) reef habitats are frequently found the sandy-bottomed pool, there are a number of patch exhibiting higher reef fish diversity, abundance, and reefs surrounded by sand at 11–13 m depth. The second stability than continuous reef habitats (Ault and Johnson pool has a similar topography to the first but is shallower 1998a; Nanami and Nishihira 2001, 2003; Belmaker with the continuous reef slope reaching 6–7 m deep and et al. 2009). This trend has been attributed to differences patch reefs found around the sandy bottom at 6–8m. in physical characteristics, limits on post-settlement movement due to increased predation pressure, or vari- Study species ation in larval supply (Ault and Johnson 1998a, b; Nanami and Nishihira 2001; Belmaker et al. 2011). Seven Acropora spp. were included in the surveys: However, none of these studies have investigated if, in A. gemmifera, A. samoensis, A. secale, A. valida, A. addition to different pressures, patchy reef habitats pos- eurystoma, A. digitifera, and A. selago. Four site- sibly contain coral colonies with ideal morphological attached Pomacentrid damselfish species, all of which characteristics. seek shelter within branching coral colonies, were studied. Environ Biol Fish Fig. 1 The Gulf of Aqaba in the northern Red Sea. Dahab, on the transect location, except T6 where only two transects were exam- Sinai Peninsula, is indicated. Inset shows location of the two ined due to topographical constraints (images attained from Goo- sample sites (the Islands and Suleiman Reef) and the transect gle Earth; large image: image © 2011 GeoEye, image © 2011 locations in each (T1-T6). Each transect was 50 m long. Three DigitalGlobe, © Cnes/Spot Image, © 2010 Google; inset image: transects at different depths and reef types were assessed at each image © 2012 DigitalGlobe, © 2010 Google) These were: the whitetail dascyllus Dascyllus aruanus, continuous reef ended at 6–7 m depth. In total, six the Red Sea dascyllus D. marginatus, the blue-green transects in the patchy reef (7–13 m) and 11 transects chromis Chromis viridis, and the Arabian chromis in the continuous reef (5–10 m) were conducted. C. flavaxilla. No other damselfish species were found All Acropora spp. colonies ≥20 cm diameter ((width inhabiting these Acropora spp.