Overlap between marine predators and proposed Marine Managed Areas on the Patagonian Shelf.

Static (fixed-boundary) protected areas are key ocean conservation strategies, and marine higher predator distribution data can play a leading role toward identifying areas for conservation action. The Falkland Islands are a globally significant site for colonial breeding marine higher predators (i.e., seabirds and pinnipeds). However, overlap between marine predators and Falkland Islands proposed Marine Managed Areas (MMAs) has not been quantified. Hence, to provide information required to make informed decisions regarding the implementation of proposed MMAs, our aims were to objectively assess how the proposed MMA network overlaps with contemporary estimates of marine predator distribution. We collated tracking data (1999-2019) and used a combination of kernel density estimation and model-based predictions of spatial usage to quantify overlap between colonial breeding marine predators and proposed Falkland Islands MMAs. We also identified potential IUCN Key Biodiversity Areas (pKBAs) using (1) kernel density based methods originally designed to identify Important Bird and Biodiversity Areas (IBAs) and (2) habitat preference models. The proposed inshore MMA, which extends three nautical miles from the Falkland Islands, overlapped extensively with areas used by colonial breeding marine predators. This reflects breeding colonies being distributed throughout the Falklands archipelago, and use being high adjacent to colonies due to central-place foraging constraints. Up to 45% of pKBAs identified via kernel density estimation were located within the proposed MMAs. In particular, the proposed Jason Islands Group MMA overlapped with pKBAs for three marine predator species, suggesting it is a KBA hot spot. However, tracking data coverage was incomplete, which biased pKBAs identified using kernel density methods, to colonies tracked. Moreover, delineation of pKBA boundaries were sensitive to the choice of smoothing parameter used in kernel density estimation. Delineation based on habitat model predictions for both sampled and unsampled colonies provided less biased estimates, and revealed 72% of the Falkland Islands Conservation Zone was likely a KBA. However, it may not be practical to consider such a large area for fixed-boundary management. In the context of wide-ranging marine predators, emerging approaches such as dynamic ocean management could complement static management frameworks such as MMAs, and provide protection at relevant spatiotemporal scales.

Chemical lipid extraction or mathematical isotope correction models: should mathematical models be widely applied to marine species?

RATIONALE: Chemical lipid extractions, as means of standardizing sample preparations, have been identified as important for comparability of studies. Unfortunately, these methods are expensive, because of the costly chemicals and the need to analyse two sets of samples, one for δ(13) C values (treated) and another for δ(15) N values (untreated). To avoid this, studies have suggested mathematical solutions to the problem. Our study intends to (i) determine the applicability of the five most common mathematical correction models and (ii) which of the widely applied chemical extraction methods is the most suitable for a variety of marine organisms. METHODS: Muscle, heart and liver samples were collected from eight different species. The tissues were treated with Bligh and Dyer, Folch and Soxhlet extraction methods and analysed in a Europa 20-20 mass spectrometer. Predicted lipid-extracted δ(13) C values were calculated from untreated tissue values using the five most common mathematical models. RESULTS: The results indicated that the mathematical methods could not be accurately applied to any of the eight species used in this study, highlighting current issues with accepted isotope methodologies. The Folch chemical extraction removed the highest amount of lipid, suggesting it is the most suitable delipidation method. CONCLUSIONS: Analysing two samples, one treated one not, remains the best method to obtain accurate δ(13) C isotope values of muscle tissue. By using this approach every study will obtain two datasets, eventually providing a suitable collective dataset for determining how isotopic signatures are affected by delipidation and potentially producing better mathematical correction models in future.

The effects of preservation methods, dyes and acidification on the isotopic values (δ15N and δ13C) of two zooplankton species from the KwaZulu-Natal Bight, South Africa.

Stable isotope measurements are an important tool for ecosystem trophic linkage studies. Ideally, fresh samples should be used for isotopic analysis, but in many cases organisms must be preserved and analysed later. In some cases dyes must be used to help distinguish organisms from detritus. Since preservatives and dyes are carbon-based, their addition could influence isotopic readings. This study aims to improve understanding of the effects of sample storage method, dye addition and acidification on the δ(15)N and δ(13)C values of zooplankton (Euphasia frigida and Undinula vulgaris). Zooplankton was collected and preserved by freezing, or by the addition of 5% formalin, 70% ethanol, or 5% formalin with added Phloxine B or Rose Bengal, and stored for 1 month before processing. Samples in 5% formalin and 70% ethanol were also kept and processed after 3 and 9 months to study changes over time. Formalin caused the largest enrichment for δ(13)C and a slight enrichment for δ(15)N, while ethanol produced a slight depletion for δ(13)C, and different effects on δ(15)N depending on the species. In formalin, dyes depleted the δ(13)C values, but had variable effects on δ(15)N, relative to formalin alone. Acidification had no significant effect on δ(15)N or δ(13)C for either species. Long-term storage showed that the effects of the preservatives were species-dependent. Although the effects on δ(15)N varied, a relative enrichment in (13)C of samples occurred with time. This can have important consequences for the understanding of the organic flow within a food web and for trophic studies. .