Glossary

Amphipods

Small crustaceans abundant in aquatic and intertidal environments, important in the marine food chain.

Anchovy

A small bony fish of the family Engraulidae, whose scientific name is Engraulis encrasicolus, also known as the European anchovy.

Anthropogenic pressures

Negative impacts caused directly by human activities on the environment, affecting terrestrial and aquatic ecosystems and the atmosphere. These include pollution, changes in land use, resource extraction, atmospheric emissions and disturbance, resulting in biodiversity loss and ecosystem degradation.

Antioxidant capacity

The ability to neutralise free radicals and reduce cellular damage.

Avian influenza

A contagious viral disease affecting birds (both wild and domestic, with a high mortality rate) and which can, in rare cases, infect mammals, including humans. It is caused by the Influenza A (H5N1) virus and transmitted through direct contact with infected animals or contaminated environments.

Beach seine

A fine-meshed and generally visible net used by small vessels to catch small pelagic fish such as sardines, mackerel and horse mackerel, as well as demersal or benthic species. This fishing gear is typically deployed from a vessel and may be operated either from shore (usually a beach) or from the vessel itself.

Benthic organisms

Organisms that live associated with the seabed or sediments.

Bioaccumulation

The process by which chemical substances build up in the tissues of an organism over time.

Bioindicator

A species or group of species whose presence, abundance or physiological state reflects the environmental conditions of an ecosystem.

Biomass

The total quantity of an animal or plant population present in a given ecosystem, usually expressed in units of weight.

Biome

A group of ecosystems that share a certain degree of homogeneity.

Biotope

An environment in which the biotic community carries out its activities. It generally exhibits regularity in environmental conditions and in animal and plant populations. Forests, lakes, a puddle of water, tree canopies, or even the backs of animals can be considered biotopes.

BirdLife International

An international non-governmental organisation (NGO) that promotes the conservation of birds, their habitats and global biodiversity, with representation in 120 countries through other local and national NGOs. SPEA is the representative in Portugal of BirdLife International.

Birds Directive

European Directive 79/409/EEC on the conservation of wild bird species occurring within the European Union, through various measures and the creation of Special Protection Areas (SPAs). Annex I of this directive lists the species for which SPAs must be established.

Bivalves

Molluscs with two shells, such as clams and cockles, common in intertidal environments.

Black tide

A phenomenon resulting from an accidental or deliberate discharge of petroleum products into the sea, usually from an oil tanker. It leads to contamination of the marine environment, with highly destructive and sometimes irreversible effects.

Boreal

A term used to describe subarctic forests located at very high latitudes around the North Pole, consisting mainly of coniferous trees (pines, firs, etc.).

Breeding strategy

A set of characteristics and behaviours that determine how a species invests in breeding, including number of chicks, breeding frequency and parental care.

Bycatch

Refers to the unintentional capture of marine species during fishing. Animals may become entangled in hooks or fishing nets. It is usually associated with commercial fishing, but can also occur in recreational fishing. Bycatch is one of the main threats to seabirds at sea.

Capture-recapture

A statistical method for estimating population size based on marked and recaptured individuals.

Cephalopods

A group of marine molluscs that includes squids, cuttlefish and octopuses.

Chlorophyll a

An indicator of phytoplankton biomass and primary productivity.

Chronic effects

Long-term effects resulting from prolonged exposure to toxic agents.

Circadian cycles

Internal biological rhythms of approximately 24 hours regulated by light and darkness.

Climate change

Persistent changes in global or regional climate patterns, influenced by natural and anthropogenic factors.

Coastal surveys

Systematic surveys conducted along the coastline to detect dead or weakened birds and other environmental indicators.

Coastal upwelling

A phenomenon involving interaction between the ocean and the atmosphere, in which warm surface waters move away from the coast and are replaced by cooler, nutrient-rich waters from the depths.

Conservation status

Classification of the threat level of a species according to its probability of extinction. The criteria for this classification generally follow internationally recognised rules defined by the International Union for Conservation of Nature (IUCN) (http://www.redlist.org) and are based on population size, range and population trend. This status may be national or international.

Continental shelf

The portion of the seabed that begins at the coastline and slopes gently downwards to the continental slope (where the slope is much steeper). On average, the continental shelf extends to a depth of 200 metres.

Continental slope

A portion of the seabed with a very steep gradient lying between the continental shelf and the continental margin, where the abyssal plains begin.

Crustaceans

A group of marine arthropods that are important in the marine food chain.

Decapods

Order of crustaceans including crabs, prawns and crayfish.

Decarbonisation

Reduction of carbon emissions associated with energy production.

Demersal

A marine organism, usually a fish, that spends most of its life on the seabed, associated with the marine substrate, which may be sandy or rocky. However, these organisms are capable of active swimming, thus differing from benthic organisms.

Discards

The portion of the catch taken by commercial fishing vessels that is returned to the sea, often dead or dying. Discarded fish often belong to species of no commercial value, individuals below the minimum legal landing size, or individuals whose landing is not permitted, for example due to quota restrictions. Discards may also consist of parts of the catch, namely offal and heads, which, after on-board processing, are rejected and discarded at sea. Discards have a strong impact on marine ecosystems and influence many aspects of the distribution, foraging behaviour and population dynamics of seabirds, particularly species and individuals that habitually follow vessels.

Disease outbreaks

A sudden increase in the incidence of a disease within a population or region.

East Atlantic Flyway

A migratory route used by birds travelling between their breeding grounds in the United States, Canada, Greenland, Siberia and northern European countries, and their wintering grounds stretching from Western Europe to the South African coast. This is one of the eight major routes used by waders and coastal birds worldwide, and is used by tens of millions of birds annually.

Ecological connectivity

The degree of connection between different areas or components of an ecosystem, allowing the flow of organisms, energy or matter.

Ecological indicator

A species or parameter that reflects the state of an ecosystem or environmental changes.

Ecological restoration

The process of recovering degraded ecosystems with the aim of restoring their original structure and function.

Ecological threshold

A reference value used to determine whether or not a population has reached a desired state.

Endemic species

A term used in biology (endemism, from the Greek endemos, meaning indigenous) to describe living organisms whose range is confined to a restricted region (e.g. a mountain, an island or a country).

Environmental status

A concept defined under the Marine Strategy Framework Directive (MSFD), referring to the condition of the elements of the marine environment, including birds. It aims to assess whether ecosystems are healthy, balanced and capable of supporting ecological functions and human uses in a sustainable manner. The ultimate goal is for the components and ecosystems to achieve Good Environmental Status.

Epipelagic

Relating to the surface layer of the ocean (up to a depth of around 200 m), where high biological productivity occurs.

Eradication

Complete removal of an invasive species from a specific area.

ESAS censuses

Standardised methodology for counting seabirds from vessels (“European Seabirds At Sea”), used to estimate distribution and density on the open sea.

Eutrophication

Excessive enrichment of water with nutrients, leading to uncontrolled algal growth.

Exclusive Economic Zone (EEZ)

Under the United Nations Convention on the Law of the Sea, coastal states are entitled to declare an EEZ comprising maritime area beyond their territorial waters. The national EEZ is delimited by an imaginary line situated 200 nautical miles from the coast, separating national waters from international or shared waters. Within its EEZ, each state has rights such as the exploitation of marine resources, the conduct of scientific research and the regulation of fishing by foreign vessels.

Extreme weather events

Intense meteorological phenomena such as storms, heatwaves or droughts.

Fish stock

A term used in fisheries science referring to a population unit of fish (or shellfish) that is commercially exploited, belonging to the same species, within a given geographical area, and harvested by a specific fishery.

Fishing gear

Equipment used to catch marine animals, such as nets, longlines or traps.

Free radicals

Unstable molecules that can cause cellular damage.

Gastropods

A group of molluscs that includes snails and whelks, common in coastal habitats and frequently consumed by waders.

Geolocator (GLS)

A small device attached to birds to study their large-scale movements (usually migration), which works by recording light intensity (from which the duration of night and the local midday time are estimated, and consequently the latitude and longitude on each day).

Gillnet

A static net, often nearly invisible and with variable mesh size, used to catch a wide variety of fish. It is set in the sea at varying depths and later retrieved. It is a non-selective fishing gear that frequently catches seabirds, marine mammals and reptiles.

GPS

A small device attached to birds to study their movements at a finer scale (usually during the breeding season). These devices use the Global Positioning System (GPS) to obtain information on position, latitude, longitude and altitude at any point on Earth, using a network of orbiting satellites.

GPS-GSM

A small device similar to a GPS, but which includes the additional functionality of sending data via the GSM network (mobile telecommunications network), thereby avoiding the need to retrieve the device to access the recorded data. Consequently, this device allows the study of bird movements over longer periods of time, whilst maintaining the accuracy of GPS systems. These devices usually also have a small solar panel to ensure they remain operational for several months or even years.

Gran Sol

The Sole Bank is a fishing ground located in the North Atlantic, to the west and south-west of the British Isles. Due to its great fish abundance, it is an area heavily exploited by European fishing fleets, particularly by vessels from Galicia, Spain.

Habitats Directive

European Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora occurring within the European Union, with the exception of birds (protected under the Birds Directive) through various measures and the establishment of Special Areas of Conservation (SACs), contributing to the Natura 2000 network.

Harmful algal blooms (HAB)

Excessive proliferation of microalgae that produce toxins or cause negative ecological impacts.

Headland

A rocky, steep and prominent geographical area that projects into the sea, often forming a cape.

Important Bird and Biodiversity Areas (IBAs)

Sites of global importance for bird conservation, forming a vital network for the conservation of birds with an unfavourable conservation status. They are identified by BirdLife International using scientific criteria.

Individual tracking

Monitoring the movements of individuals using tracking devices.

Intertidal substrate

Coastal zone between high and low tide, subject to alternating submersion and exposure.

Intertidal zone

The coastal area that is exposed at low tide and submerged at high tide.

Introduced or exoticspecies

A term generally applied to a species introduced deliberately or accidentally into a specific location or region outside its original range. Depending on its adaptation to the new environment, an introduced species may or may not become naturalised and proliferate.

Invasive species

An introduced or non-native species that, due to its successful adaptation to new conditions, is able to achieve exceptional population growth. This increase may be so significant that it can threaten native species that share the same resources.

Invasive species control

Population management of invasive species without total elimination.

Kleptoparasitism

A feeding method in which one individual steals food from another.

Krill

Small crustaceans of the order Euphausiacea found in all oceans. Krill are considered an important prey source for many vertebrate species such as birds, seals, whales and fish that inhabit sub-Antarctic waters, forming the base of the food chain.

Lemming

Name given to a group of small herbivorous rodents found in the Arctic tundra and sub-Arctic regions, belonging to the family Cricetidae.

LIFE

The LIFE+ Programme funds projects that contribute to the development and implementation of environmental policy and legislation. In particular, this programme facilitates the integration of environmental issues into other policies and, more broadly, contributes to sustainable development.

Light pollution

Alteration of natural night-time light levels due to artificial lighting.

Longline

A fishing gear consisting of a main line (mother line) from which secondary lines with hooks attached branch off. It is left in the sea and can be placed on the seabed to catch deep-sea species (e.g. scabbardfish) or at the surface to catch large pelagic fish (e.g. swordfish).

Macaronesia

A biogeographical region comprising the archipelagos of the Azores, Madeira, the Canary Islands and Cape Verde.

Marine censuses

Standardised bird counts carried out at sea to estimate abundance and distribution.

Marine Strategy Framework Directive (MSFD)

European Directive 2008/56/EC to protect the marine ecosystem and biodiversity within the European Union, helping Member States achieve good environmental status of the marine environment.

Marshes

Freshwater wetlands, often temporary or shallow, used by waterbirds.

Mature individuals

Individuals capable of breeding, used as a reference in population estimates.

Mesopelagic

A marine organism living in the water column generally between 200 and 1,000 metres in depth.

Mesopelagic zone

Intermediate oceanic layer (approximately 200–1,000 m deep), characterised by low light levels and vertical migration of organisms.

Microplastics

Plastic particles smaller than 5 mm.

Migratory corridors

Preferred routes and geographical areas where the movement of individuals is concentrated during migrations.

Mitigation measures

Actions designed to reduce or minimise negative impacts on species or ecosystems.

Moult

A biological phenomenon characteristic of birds, through which the plumage is renewed. It can be partial or total and generally occurs at specific times of the year, depending on the species in question.

Mustelids

Carnivorous mammals belonging to the family Mustelidae. This family, the largest in the order Carnivora, includes ferrets, weasels, martens, otters, badgers and many more.

NACES

North Atlantic Current and Evlanov Sea Basin Marine Protected Area (NACES) designated in 2021 with the specific aim of conserving migratory seabirds. NACES is located in the centre of the North Atlantic, between the Azores, the United Kingdom, Canada and Greenland.

Natura 2000 Network

A network of areas designated to conserve habitats and wild species in the European Union. It results from the implementation of two EU directives: the Birds Directive and the Habitats Directive, concerning the protection of habitats and wild fauna and flora.

Nest boxes (artificial nests)

Artificial structures installed to provide alternative nesting sites and increase breeding success.

Oceanic fronts

Transition zones between water masses with different characteristics (temperature, salinity), frequently associated with high biological productivity.

Oceanic waters (Offshore)

Waters situated away from the coast, beyond the continental shelf. It is used in matters relating to maritime activities, such as fishing, the oil industry and the exploitation of renewable energy. These waters are characterised by being located in the open sea, at great depths and far from coastal influences such as rivers and estuaries. They are thus distinguished from coastal waters.

Offshore wind farms

Wind energy production infrastructures installed at sea.

Oligotrophic waters

Waters that are low in nutrients and generally have low biological productivity.

Osmoregulation

The process by which organisms regulate the balance of water and salts in the body.

OSPAR

An international convention for the protection of the marine environment of the North-East Atlantic, responsible for defining environmental indicators and targets.

Overfishing

A form of fishing in which fish stocks (or populations) are exploited to levels that are biologically and ecologically unsustainable. Overfishing of certain key species, such as sharks, can lead to the collapse of marine ecosystems.

Oxidative stress

An imbalance between the production of free radicals and the organism’s antioxidant capacity.

Pantropical distribution

Geographical distribution covering tropical regions of various oceans or continents.

Paretic syndrome

A set of neurological symptoms characterised by weakness and partial paralysis.

Passive acoustic monitoring

A method of detecting species through the continuous recording of vocalisations in a natural environment.

Peatlands

Wetland ecosystems characterised by the accumulation of partially decomposed organic matter, of high ecological importance.

Pelagic

The area or environment where organisms that do not depend on the seafloor normally live. It is the typical ecological environment of open ocean waters. The pelagic ecosystem does not include only the open sea; it also comprises the waters covering the continental shelf. The pelagic zone begins below the influence of tides and extends into the open ocean, at depths ranging from a few tens of metres to approximately 6,000 metres, and is divided into different layers.

Persistent organic pollutants (POPs)

Chemical compounds resistant to degradation that accumulate in organisms and the environment.

Phenology

The study of periodic phenomena in living organisms and their relationship with the environment, such as temperature, light and humidity. Some of these cyclical phenomena include, for example, bird migration or plant flowering.

Philopatry

The behaviour of returning to the place of birth to breed.

Plankton

Aquatic organisms, generally small, which are suspended in the water and drift with the currents. Plankton may consist of plants (phytoplankton), animals (zooplankton) or other organisms such as bacteria.

Polychaetes

Annelid worms belonging to the class Polychaeta.

Polycyclic aromatic hydrocarbons (PAHs)

A group of toxic organic compounds found in petroleum with carcinogenic and endocrine-disrupting potential.

Population trend

The direction of change in the size of a population over time (increase, decline or stability).

Post-breeding

Referring to the period following breeding.

Pre-breeding

Referring to the period preceding breeding.

Productivity

Quantity of organic matter produced per unit of time (usually one year). Primary productivity refers to the quantity of organic matter produced by primary producers: algae in aquatic or marine environments, or plants in terrestrial environments.

Productivity (seabirds)

A measure of a population’s breeding success, generally expressed as the average number of chicks produced per pair.

PTT

The PTT (platform transmitter terminal) is a small device attached to birds to study their large-scale movements (generally migration and wintering, but also breeding). These devices use the Argos satellite system to obtain information on position, latitude, longitude and altitude, anywhere on Earth, via a network of satellites in orbit. They are as accurate as GPS devices.

Purse seine

A typically small-mesh, highly visible net used by purse seiners to catch small pelagic fish such as sardines or mackerel. After locating a school, the net is deployed from a vessel and encircles it completely, preventing the fish from escaping, and is then hauled in. When properly operated, it is a selective fishing gear.

Raft

A gathering of seabirds resting on the sea surface (mostly medium-sized or large Procellariiformes). As they bring together a large number of individuals in a relatively confined space, these groups give the illusion of being rafts.

RAM censuses

Coastal observation network for seabirds and marine mammals, based on systematic counts along the coastline.

Riparian gallery

Tree or shrub vegetation associated with riverbanks and watercourses.

Salt glands

Specialised structures that allow birds to eliminate excess ingested salt, essential for marine life.

Sand eel

A generic common name given to various species of bony fish of the genus Ammodytes.

Scavenger

An animal that feeds on carcasses or parts of them, actively seeking them out but without hunting.

Seamount

An underwater mountain rising from the ocean floor without reaching the surface, usually of volcanic origin, with a conical shape and a circular, elliptical or slightly elongated base. Only elevations exceeding 1,000 metres are considered seamounts.

Site of Community Importance (SCI)

An area considered important for the conservation of habitats and species characteristic of a European biogeographical region, in accordance with the Habitats Directive.

Snapshot method

Instantaneous sampling technique used to count birds in flight, avoiding double counting.

Southern range limit

The southernmost extent of a species’ range.

Special Protection Area (SPA)

An area of Community importance where measures are applied to maintain or restore the conservation status of populations of wild bird species listed in Annex I of the Birds Directive. These are intended for the species mentioned in that annex and aim to ensure their survival and breeding, the conservation of their eggs, nests and habitats, as well as for migratory bird species not referred to in that annex but which occur regularly within the national territory.

Species distribution modelling (SDM)

A statistical approach that relates the occurrence/abundance of species to environmental variables.

Stranding

A dead or moribund animal that is brought ashore by the action of winds and ocean currents.

Submarine outfall

A structure that discharges wastewater into the sea after it has undergone a certain level of treatment at a wastewater treatment plant (WWTP). The dynamics of marine waters promote the natural processes of dilution, dispersion and degradation of these waters.

Synanthropic

Species that live in association with human environments or benefit from them.

Thyroid homeostasis

The physiological regulatory process that ensures the balanced production and release of hormones essential for metabolism, growth and the functioning of most organs in the body.

Time series

A set of data collected consistently over time, used to analyse trends.

Top predator

A species occupying the highest levels of the food chain and having no significant natural predators.

Transoceanic migration

Long-distance migratory movement across vast oceans, linking breeding and wintering grounds separated by thousands of kilometres.

Trophic niche

The position of a species within the food chain, including the type of food it consumes and its ecological role.

Tundra

The name given to the extensive plains with low-growing vegetation and no trees, characteristic of Arctic and sub-Arctic regions. The tundra is generally a very cold region with low precipitation.

Uropygial gland

A gland located at the base of a bird’s tail that produces an oily substance, known as uropygial oil, used for the maintenance and waterproofing of the feathers.

Vertical migration

Daily movement of organisms between deep and surface layers of the water column.

Wader

A group of birds associated with coastal or inland wetlands, generally found in habitats such as mudflats, saltmarshes, estuaries, lagoon margins, sandy areas and flooded zones. Some of these species also use the sandy and rocky coasts of Portugal.

Wintering grounds

Areas where birds remain outside the breeding season, generally associated with favourable conditions for feeding and survival.

Wintering period

A period generally corresponding to the winter months, which may include part of autumn.

WWTP

Abbreviation used to refer to a wastewater treatment plant.