Reef manta ray (Meters. alfredi) sightings and associated hitchhiker variety (1987–2019)

Spatial type on the presence really appear to seen hitchhiker species with Yards. alfredi (adult and you may juvenile Age. naucrates) was indeed investigated by the mapping the newest percentage of sightings at each website (categorized of the site setting) where hitchhiker variety is establish (total number off sightings in which hitchhikers had been noticed / final amount of sightings at website) in the ArcGIS 10.eight. People internet sites with all in all, 9 or less sightings (213 internet sites) was omitted to reduce the new bias a reduced quantity of sightings possess on studies.

Temporal adaptation regarding the presence of mature and you may teenager E. naucrates which have M. alfredi was examined playing with monthly go out show. It collection incorporated that time on the top level of sightings (2008–2019) to add an appropriate period of which to help you visualise manner (we.elizabeth., seasonality). This new month-to-month final number of sightings have been remedied for questionnaire effort by figuring the mean month-to-month level of manta light noticed for each questionnaire (monthly overall manta ray sightings / monthly total number regarding studies).

Generalised linear mixed designs.

Logistic generalised linear mixed models (GLMM) using R v4.0.0 were used to investigate relationships between the presence of the most frequently observed hitchhiker species (adult and juvenile E. naucrates, G. speciosus, and Lutjanus bohar) with M. alfredi and four explanatory variables: sex with pregnancy status, maturity status, site function (determined by the predominant behaviour observed at the site ), and seasonality (NE or SW Monsoon). Due to the low number of recorded associations between M. alfredi and most of the hitchhiker species, only those with sufficient data were included in the GLMM analysis. The same model was used for Remora remora (the most frequently observed hitchhiker species with M. birostris), but without site function, and sex was classified only as male or female as pregnancies were only observed during four sightings. Each GLMM was fitted with a logit link function to the binary response of hitchhiker species presence (1) and absence (0) using the ‘lme4′ R package . Each model contained the manta-ID as a random intercept to account for any temporal autocorrelation arising from individual rays being repeatedly observed . To compare the relative goodness-of-fit, GLMM models without random effects (GLM) were tested. To reliably estimate the parameters, categories of variables with levels observed equal to or less than five times were removed. For example, under the category behavioural activity, the level ‘breaching’ was observed on less than five occasions, so was removed from analysis. The most informative explanatory variables were identified by firstly testing GLMM models with all combinations of explanatory variables. The variance inflation factor (VIF) was used to test models for multicollinearity; the maximum VIF was <1.5. Model performance was assessed using corrected Akaike information criterion (AICc) test statistic using the ‘MuMin' R package , and the DHARMa R package was used to check the model residuals were normally distributed. The highest-ranking models (with the lowest AICc value, S1 Table) for each hitchhiker species were then interpreted in terms of odds ratios (ORs) (the likelihood of the presence of the hitchhiker species in comparison with the reference category). Any models with ?AICc <2 were considered in interpretation of the highest-ranking model . The significance of each explanatory variable was determined by the 95% confidence interval (CI) of OR, whereby a narrower CI indicates a more precise estimation while, in comparison, a wider CI which had a greater uncertainty. A CI that crossed one is considered non-significant. Any ORs with p > 0.05 are not reported.

Efficiency

All in all, 4901 Yards. alfredi was indeed truly understood [male = 2442 (50%), female = 2459 (50%)] through the a maximum of 72912 sightings, at which 44071 (60%) was of women [adult = 25700 (58%), juvenile = 18371 (42%)] and you may 28841 (40%) were people [mature = 25968 (90%), subadult = 1443 (5%), teenager = 1430 (5%)]. Every sightings took place across 353 web sites want Polyamorous dating reviews, at which 95 (27%) were clean up stations [sightings = 24034 (33%)], 53 (15%) was driving components [sightings = 129 (0%)], and you will 205 (58%) feeding areas [sightings = 48749 (67%)].