Interactions between seabirds and pollution in Irish waters

Abstract

Seabirds are abundant and ubiquitous globally. They suffer pressure from many contemporary threats such as fisheries, invasive species and pollution. This thesis focuses on two different types of pollution: plastic litter and persistent organic pollutants (POPs). Plastic litter affects seabirds in two main ways: ingestion and entanglement. At least 50% of the world’s seabird species have been affected by plastic pollution in one way or another. Persistent organic pollutants are toxic compounds used in industry and sometimes produced naturally or as an unintentional by-product of anthropogenic activities. POPs are persistent in the environment, of toxic nature, have volatile properties and can bio-accumulate in biota. Legislation has been used to ban or restrict the use of most POPs and now concentrations of such substances are monitored to make sure they reach safe levels until complete elimination. Legislation has also called for monitoring of marine litter in the environment and in biota. As seabirds feed at a variety of trophic levels, they can provide information linked to all trophic levels. They have been extensively studied, are abundant and long-lived, making them ideal candidates for monitoring environmental changes, even when subtle. Data for both types of pollutants’ interactions with seabirds are scarce in Ireland, even though the islands of Ireland and Britain have a total population of almost 8 million seabirds. The need to investigate the presence, levels and how such pollutants interact with seabird species was eminent, not only for a matter of scientific research, but also to assess the threat posed to seabirds in the context of legislative requirements to monitor the health of their populations.

This research aimed to establish baseline levels of plastic and persistent organic pollutants in seabirds breeding in Ireland, along with the testing of different methodologies that may be appropriate for Ireland to implement monitoring such as the Oslo-Paris Convention (OSPAR) Ecological Quality Objectives (EcoQOs) should that become government policy. For that, Chapter 1 presents the background of what is known about these pollutants, how they can affect wildlife and seabirds, why it is important to monitor pollutants in seabirds and the knowledge gap in Ireland. Chapter 2 of this dissertation encompasses the suitability of beached bird surveys for marine Vlitter monitoring, baseline levels of plastic ingestion through stomach analysis, as well as an investigation of suitable species to comply with international monitoring programmes such as EcoQOs. Chapter 3 investigates alternative monitoring strategies for marine litter, this time via opportunistic sampling of live birds that are handled in colonies for banding or other research and through the collection of boluses as a passive diet sampling. This type of sampling allowed for chicks and parents to be investigated for plastic ingestion. Chapter 4 focuses on a single species, the European Storm Petrel (Hydrobates pelagicus), for persistent organic pollutant investigation. This chapter intended to establish baseline levels for different types of POPs in Storm Petrels in Ireland, but also to test different methodologies for live sampling for POPs. In this context, preen oil and feathers from the same birds were collected for investigation. Chapter 5 also focused on a single species, the Common Tern (Sterna hirundo) to investigate POP concentrations for Common Terns in Ireland, also testing different methodologies for live birds (preen oil and feathers), but additionally, sampling dead birds found in the same colony (which were investigated for plastic pollution as well), utilising two internal organs (liver and preen gland). This species is also used as a monitor for POPs in international monitoring programmes. Therefore, the investigation of such species in Ireland adds to the body of research needed to establish compliance with monitoring. Finally, chapter 6 addresses the conclusions incorporated by this research and how it fits to the current pollutant information globally, and informs policy in Ireland.