Impact of phosphorus loadings on macro-algal communities in the Red Sea coast of Egypt

Abou-Aisha, Kh. M.; Kobbia, I. A.; Abyad, M. S. El; Shabana, E. F.; Schanz, Fritz

doi:10.1007/bf00477358

Cited by 15 publications

(5 citation statements)

References 14 publications

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“…polychaetes) to contain metal tolerant species in both hard substrate and soft sediment communities [51], [57], [58]. However, more commonly, elevated species richness and abundance in heavily contaminated areas have been associated with organic enrichment [59], [60], [61].…”

Section: Discussionmentioning

confidence: 99%

Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants

et al. 2013

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Ecological communities are increasingly exposed to multiple chemical and physical stressors, but distinguishing anthropogenic impacts from other environmental drivers remains challenging. Rarely are multiple stressors investigated in replicated studies over large spatial scales (>1000 kms) or supported with manipulations that are necessary to interpret ecological patterns. We measured the composition of sediment infaunal communities in relation to anthropogenic and natural stressors at multiple sites within seven estuaries. We observed increases in the richness and abundance of polychaete worms in heavily modified estuaries with severe metal contamination, but no changes in the diversity or abundance of other taxa. Estuaries in which toxic contaminants were elevated also showed evidence of organic enrichment. We hypothesised that the observed response of polychaetes was not a ‘positive’ response to toxic contamination or a reduction in biotic competition, but due to high levels of nutrients in heavily modified estuaries driving productivity in the water column and enriching the sediment over large spatial scales. We deployed defaunated field-collected sediments from the surveyed estuaries in a small scale experiment, but observed no effects of sediment characteristics (toxic or enriching). Furthermore, invertebrate recruitment instead reflected the low diversity and abundance observed during field surveys of this relatively ‘pristine’ estuary. This suggests that differences observed in the survey are not a direct consequence of sediment characteristics (even severe metal contamination) but are related to parameters that covary with estuary modification such as enhanced productivity from nutrient inputs and the diversity of the local species pool. This has implications for the interpretation of diversity measures in large-scale monitoring studies in which the observed patterns may be strongly influenced by many factors that covary with anthropogenic modification.

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Section: Discussionmentioning

confidence: 99%

Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants

et al. 2013

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“…If the comparison is based on SRP concentrations, the studied reefs present the highest values of nearly all sites depicted in Table 2, the only exception being the nearshore reefs of Safaga and Quseir, in the Red Sea (ABOU-AISHA et al, 1995), which receive large phosphorus loading from phosphate factories near the coast. Results from a 20year study in Florida have shown that phosphorus is a key factor controlling the growth of reef building corals (HBOI, 2006).…”

Section: Comparison With Other Reef Areasmentioning

confidence: 99%

Anthropogenic nutrient pollution of coral reefs in Southern Bahia, Brazil

Costa

2007

Braz. j. oceanogr.

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Spatial, temporal and anthropogenic controls on nutrient distribution were evaluated for nearshore and offshore reefs at Porto Seguro Bay, Southern Bahia. Water samples were analysed for total oxidised nitrogen (TON), soluble reactive phosphorus (SRP), reactive silica (DSi), and chlorophyll a (Chl). The results indicate that rainfall promotes a significant (F=19.873, p<0.001) increase in the load of nutrients to nearshore (average 12% increase) and offshore reefs (average 31% increase). Nutrient concentrations at the urbanized reef (TON=1.93-3.21µM; SRP=0.57-0.89µM; DSi=8.48-11.15µM) are on average 25% higher than at non-urban reefs and over 200% higher than the offshore reef. The urbanized reef also presented the highest rates of increase in nutrient input between dry and rainy seasons (TON=+0.36µM; SRP=+0.08µM; DSi=+0.70µM). Differences in nutrient concentration between nearshore and offshore reefs are more pronounced during dry season, when the bulk of land-based nutrient contribution is confined to the nearshore reefs. SRP values in the study area ranked among the highest in the world for coral reef areas and phytoplankton growth appears to be nitrogen-limited.
Este artigo discute os fatores espaço, tempo e atividade antrópica na distribuição de nutrientes em amostras dos recifes costeiros da Baía de Porto Seguro, sul do Estado da Bahia. Análises realizadas nas amostras d'água incluem a porção reativa de nitrogênio (TON), fósforo (SRP) e silicato (DSi) dissolvidos, e clorofila (Chl). Resultados indicam um aumento significante (F=19.873, p<0.001) na descarga de nutrientes durante a estação chuvosa para os recifes costeiros (média de 12%) e para o recife oceânico (média de 31%). O recife urbano (TON=1.93-3.21µM; SRP=0.57-0.89µM; DSi=8.48-11.15µM) apresentou concentrações 25% mais altas que o outro recife costeiro, e mais de 200% acima do recife oceânico. Aquele recife também apresentou as mais altas taxas de aumento na descarga de nutrientes entre as estações seca e chuvosa (TON=+0.36µM; SRP=+0.08µM; DSi=+0.70µM). A diferença nas concentrações de nutrientes entre os recifes costeiros e oceânico é maior durante a estação seca, quando a contribuição continental de nutrientes está confinada a áreas próximo à costa. As concentrações de fósforo inorgânico na área de estudo estão entre as mais altas do mundo para áreas coralinas, e o fitoplâncton parece ser limitado pela disponibilidade de nitrogênio

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“…This reflects the highly seasonal nature of the southern Red Sea where monsoon‐driven changes in temperature are known to cause significant changes in biomass and composition of algae (Ateweberhan et al , 2005 a , b , 2006 b ). Similarly, the monsoons are responsible for seasonality in marine biological processes in the western Indian Ocean including algal growth, fish reproduction and recruitment (Fishelson et al , ; McClanahan, ; Ormond & Banaimoon, ; Abou‐Aisha et al , ). The way in which this seasonality affects reef grazers, however, differs and appears to be related to their feeding habits.…”

Section: Discussionmentioning

confidence: 99%

Seasonal and life‐phase related differences in growth in Scarus ferrugineus on a southern Red Sea fringing reef

Tecleab

Videler

Berhane

et al. 2014

Journal of Fish Biology

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Temporal trends in growth of the rusty parrotfish Scarus ferrugineus were studied on a southern Red Sea fringing reef that experiences seasonal changes in environmental conditions and benthic algal resources. Length increment data from tagging and recapture were compared among periods and sexes and modelled using GROTAG, a von Bertalanffy growth model. The growth pattern of S. ferrugineus was highly seasonal with a maximum occurring between April and June and a minimum between December and March. Body condition followed the seasonal variation in growth, increasing from April to June and decreasing from December to March. The season of maximum growth coincided with high irradiation, temperature increases and peak abundance of the primary food source, the epilithic algal community. There was a decline in growth rate during summer (July to October) associated with a combination of extreme temperatures and lowered food availability. There were strong sexual size dimorphism (SSD) and life-history traits. Terminal-phase (TP) males achieved larger asymptotic lengths than initial-phase individuals (IP) (L(∞) 34·55 v. 25·12 cm) with growth coefficients (K) of 0·26 and 0·38. The TPs were growing four times as fast as IPs of similar size. Three individuals changed from IP to TP while at liberty and grew eight times faster than IPs of similar size, suggesting that sex change in S. ferrugineus is accompanied by a surge in growth rate. The SSD in S. ferrugineus thus coincided with fast growth that started during sex change and continued into the TP. Faster growth during sex change suggests that the cost associated with sex change is limited.

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Impact of phosphorus loadings on macro-algal communities in the Red Sea coast of Egypt

Cited by 15 publications

References 14 publications

Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants

Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants

Anthropogenic nutrient pollution of coral reefs in Southern Bahia, Brazil

Seasonal and life‐phase related differences in growth in Scarus ferrugineus on a southern Red Sea fringing reef

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