Data in the natural sciences are often in the form of percentages or proportions that are continuous and bounded by 0 and 1. Statistical analysis assuming a normal error structure can produce biased and incorrect estimates when data are doubly bounded. Beta regression uses an error structure appropriate for such data. We conducted a literature review of percent and proportion data from 2004 to 2020 to determine the types of analyses used for (0, 1) bounded data. Our literature review showed that before 2012, angular transformations accounted for 93% of analyses of proportion or percent data. After 2012, angular transformation accounted for 52% of analyses and beta regression accounted for 14% of analyses. We compared a linear model with angular transformation with beta regression using data from two fields of the natural sciences that produce continuous, bounded data: biogeochemistry and ecological elemental composition. We found little difference in model diagnostics, likelihood ratios, and p‐values between the two models. However, we found substantially different coefficient estimates from the back‐calculated beta regression and angular transformation models. Beta regression provides reliable parameter estimates in natural science studies where effect sizes are considered as important as hypothesis testing.

Rivers and estuaries are important conduits and reactors for organic matter (OM). Despite the substantial export of terrestrial OM by rivers, only a small proportion of this material reaches the open ocean. One potentially important mechanism contributing to the removal of terrestrial dissolved OM (DOM) is flocculation; a process that transforms DOM into larger size fractions that can settle into sediment pools. Here we investigate the role of flocculation in adjacent boreal coastal systems over three consecutive seasons. Flocculation experiments, which include the artificial salting of freshwater DOM to mid (12 psu) and high salinity (25 psu), and a 1:1 mixture of freshwater DOM with their respective saline endmember, highlight a potentially important source of particulate carbon (PC) in boreal estuaries. Along with a 3.5% ± 1.0% removal of dissolved organic carbon (DOC) and 44% ± 16% dissolved iron (DFe), the potential for flocculation of these constituents significantly increased with increasing salinity from 12 to 25 psu. The particulate matter (PM) produced by salt‐induced flocculation was comparable to in situ PC concentrations (in situ PC = 27.5 μmol L−1 and flocculated PC = 15.0 μmol L−1) and stable carbon isotopic signatures (in situ PM = −28.8‰ and flocculated PM = −28.3‰). DFe:DOC and Sr were the only parameters that could significantly explain the degree of carbon and iron flocculation. This demonstrates the importance of DOC, DFe, and optical properties, and the predictive value of DFe:DOC for understanding DOM susceptibility to flocculation and its relevance and contribution to regional and global carbon budgets.

Observed and predicted hydrological changes in C‐rich boreal ecosystems have the ability to change the transport trajectory of biogeochemical constituents from the land to ecologically, economically, and culturally important coastal systems. Yet, most of our current understanding of biogeochemical fluxes and cycling across salinity gradients stem from observations of large and urbanized riverine systems, which overlooks the numerically abundant smaller systems. In this study, we conducted a baseline assessment of the biogeochemical constituents across salinity gradients among two adjacent small systems in the boreal zone. Dissolved iron (DFe) and its ratio with dissolved organic carbon (DFe : DOC) were the most sensitive indicators for small catchment heterogeneity. These parameters were the best indicators of change among coastal systems across regional and seasonal scales. Our results also confirm consistencies in common optical measures (SUVA254 and S[275–295/350–400]) and DOC to nitrogen ratios that may adequately provide representation of biogeochemical composition on a regional scale. Simultaneous variation in biogeochemical parameters across particulate and dissolved pools during the summer‐to‐fall transition period indicate this as an important timeframe for targeted investigation of the linkages between biogeochemical parameters and coastal ecosystem functioning. By providing some key spatial and temporal constraints on biogeochemical fluxes among boreal river‐estuaries, our findings indicate that DFe and DFe : DOC ratios should be used to design research aimed at capturing regional and coastal ecosystem scale biogeochemical fluxes to inform Earth System Models.