Correction to: Microhabitats of sharknose goby (Elacatinus evelynae) cleaning stations and their links with cleaning behaviour

Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02111-z     

Seasonal variation in reef fish assemblages in the environmentally extreme southern Persian/Arabian Gulf

The southern Persian/Arabian Gulf experiences extreme seasonal temperature variation (> 20 °C) making it among the most hostile reef environments on Earth. Previous anecdotal evidence has suggested that seasonal temperature changes may influence regional reef fish assemblages, but to date research has been limited. To examine the influence of temperature on reef fish abundance and composition, we performed visual surveys in summer and in winter over three years at three reefs in the southern Gulf (Dhabiya, Saadiyat and Ras Ghanada). Overall abundance of fishes was 40% higher in summer than in winter, and multivariate analyses showed strong and significant differences in overall seasonal community structure, consistent at all sites and across all years. Seasonal differences were largely driven by nine of the 30 observed species, which together accounted for 70% of the divergence in community structure between summer and winter. Of these nine species, Lutjanus ehrenbergii, Lutjanus fulviflamma, Plectorhinchus sordidus and Abudefduf vaigiensis were significantly more abundant in summer, Parupeneus margaritatus and Acanthopagrus bifasciatus, were significantly more common on reefs in winter. We discuss these changes in terms of seasonal physiological and ecological constraints, and explore the implications of these changes on the functional ecology of reef fishes in this thermally variable and extreme environment.

     

Population-level impacts of natural and anthropogenic causes-of-death for Hawaiian monk seals in the main Hawaiian Islands

Identifying, assessing, and ranking the impact of individual threats is fundamental to the conservation and recovery of rare and endangered species. In this analysis, we quantify not only the frequency of specific causes-of-death (CODs) among Main Hawaiian Island (MHI) monk seals, but also assess the impact of individual CODs on the intrinsic growth rate, λ, of the MHI population. We used gross necropsy results, histopathology, and other evidence to assign probabilities of 11 COD types to each mortality and then used Monte Carlo sampling to evaluate the influence of each COD on λ. By right censoring realizations involving specific CODs, we were able to estimate λ (and its associated uncertainty) when CODs were selectively removed from influencing survival. Applying the analysis to all known and inferred deaths believed to have occurred 2004–2019, the CODs with the largest influence on λ were anthropogenic trauma, anthropogenic drowning, and protozoal disease. In aggregate, anthropogenic CODs had a larger effect on the growth rate than either natural or disease CODs. Possible bias associated with differential carcass detection, recovery, and COD classification are discussed.     

Genetic evidence for seasonal consumption of monkfish (Lophius spp.) and salmonids (Salmo spp.) by gray seals

Recoveries of gray seal (Halichoerus grypus) populations across their eastern Atlantic distribution have led to a steady increase in seal-fishery interactions. Fishers have estimated depredation of salmonids (Salmo spp.) and monkfish (Lophius spp.) as high as 40% and 59% respectively in Ireland. However, empirical evidence for the consumption of these species has been extremely limited due to diagnostic hard part remains not being found in scats or stomach samples. We applied species-specific primers and tested for the presence of monkfish and salmonids in gray seal diet genetically using quantitative polymerase chain reaction (qPCR) on scats. Monkfish occurred in 29.7% of sampled scats, while salmonids occurred in 12.7%. Seasonal and regional variability in occurrence were noted for both species, likely related to the migratory behavior of the prey species and proximity of seal haul-outs to aquaculture sites. Traditional hard part analysis of scats, including scats that tested positive for monkfish and salmonid DNA, failed to find any evidence of either species. This study provides important empirical evidence for the consumption of these species in Ireland that can inform management.     

Cryptosporidium species and subtypes in river water and riverbed sediment using next-generation sequencing

This study uncovered the prevalence, harboured species, and subtype diversity of Cryptosporidium species in river water and its sediment from the Apies River in South Africa. Cryptosporidium spp. concentrations in freshwater and its sediment were determined using Ziehl-Neelsen staining and quantitative Polymerase Chain Reaction (qPCR) techniques. Next-generation sequencing (NGS) targeting the 60 kDa glycoprotein (gp60) gene of Cryptosporidium spp. was performed to reveal the species, subtype families and subtypes harboured in freshwater and its sediment. Although the results revealed that water samples had a higher prevalence (30%) compared with sediment (28%), the number of observable Cryptosporidium spp. oocysts in sediment samples (ranging from 4.90 to 5.81 log₁₀ oocysts per 1 Liter) was higher than that of river water samples (ranging from 4.60 to 5.58 log₁₀ oocysts per 1 L) using Ziehl-Neelsen staining. The 18S ribosomal ribonucleic acid (rRNA) gene copy of Cryptosporidium in riverbed sediments ranged from 6.03 to 7.65 log₁₀, whereas in river water, it was found to be between 4.20 and 6.79 log₁₀. Subtyping results showed that in riverbed sediments, Cryptosporidium parvum accounted for 40.72% of sequences, followed by Cryptosporidium hominis with 23.64%, Cryptosporidium cuniculus with 7.10%, Cryptosporidium meleagridis with 4.44% and the least was Cryptosporidium wrairi with 2.59%. A considerable percentage of reads in riverbed sediment (21.25%) was not assigned to any subtype. River water samples had 45.63% of sequences assigned to C. parvum, followed by 30.32% to C. hominis, 17.99% to C. meleagridis and 5.88% to C. cuniculus. The data obtained are concerning, as Cryptosporidium spp. have intrinsic resistance to water treatment processes and low infectious doses, which can pose a risk to human health due to the various uses of water (for human consumption, leisure, and reuse).