On July 21, 2026, our team conducted a marine survey bioblitz at Theotokos in South-east Pelion, Greece. The survey explored shallow rocky shores and nearshore habitats, recording fish, sponges, anemones, molluscs, echinoderms, crustaceans, algae, and coastal birds.

A total of 32 taxa were recorded during the survey, including 26 identified to the species level, 2 to the genus level, and 1 to the suborder level.

Fish

• Epinephelus marginatus (Dusky Grouper)
• Boops boops (Bogue)
• Coris julis (Mediterranean Rainbow Wrasse)
• Symphodus rostratus (Pointed-snout Wrasse)
• Atherina sp.
• Blennioidei (Blennies)
• Diplodus vulgaris (Common Two-banded Seabream)
• Apogon imberbis (Mediterranean Cardinalfish)
• Symphodus tinca (East Atlantic Peacock Wrasse)
• Serranus scriba (Painted Comber)
• Serranus cabrilla (Comber)
• Oblada melanurus (Saddled Seabream)
• Chromis chromis (Mediterranean Damselfish)
• Thalassoma pavo (Ornate Wrasse)
• Diplodus sargus (White Seabream)
• Sarpa salpa (Salema Porgy)
• Mullus surmuletus (Striped Red Mullet)

Sponges

• Tethya aurantium (Golf Ball Sponge)
• Chondrilla nucula (Potato Sponge)
• Sarcotragus spinosulus (Black Leather Sponge)
• Chondrosia reniformis (Kidney Sponge)

Anemones

• Aiptasia mutabilis (Trumpet Anemone)

Molluscs

• Stramonita sp.
• Tarantinaea lignarius

Echinoderms

• Holothuria sanctori (Variable Sea Cucumber)
• Arbacia lixula (Black Sea Urchin)

Crustaceans

• Percnon gibbesi (Nimble Spray Crab)
  
  

Algae and marine plants

• Codium fragile (Dead Man’s Fingers)
• Dictyota dichotoma (Forked Ribbons)
• Padina pavonica (Peacock’s Tail)

Coastal birds

• Gulosus aristotelis (European Shag)

​How Fast Can an Alien Species Establish in the Mediterranean Through the Suez Canal?
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The Suez Canal is much more than a shipping route. Since opening in 1869, it has also connected two previously separated marine ecosystems: the Red Sea and the Mediterranean.

This has allowed hundreds of non-native organisms, often called alien species or Lessepsian migrants, to enter Mediterranean waters. But how quickly can one of these species establish and spread?

The short answer is: sometimes within a decade, although spreading across much of the Mediterranean usually takes several decades.

Arrival is not the same as establishment

A species must pass through several stages before it becomes established:

1. Arrival: individuals, eggs or larvae enter through the canal.
2. Survival: They tolerate Mediterranean temperatures, salinity, food availability, and predators.
3. Reproduction: A sufficiently large population begins reproducing successfully.
4. Establishment: The population becomes self-sustaining.
5. Expansion: It spreads to new coastlines and islands.

Many species arrive but disappear without forming permanent populations. An alien species is only considered established when it can maintain a population without repeated arrivals from its native range.

Also, not every alien species becomes invasive. That term is generally reserved for established species that spread and cause ecological, economic, or human-health impacts.

What does the research show?

A 2024 study examined 772 historical records involving 130 non-indigenous fish species that entered the Mediterranean through the Suez Canal.

The researchers found that:

- More than half of the introduced fish became established in less than 10 years.
- The first major movement beyond the initial detection region took approximately four years.
- Subsequent geographical expansion occurred in steps averaging about 2.5 years.
- Reaching the central Mediterranean from Suez took approximately 21.5–22 years.
- The dominant direction of expansion was northward and then westward, passing through the Levant, southern Turkey, Cyprus, Greece, and eventually the central Mediterranean.

These figures describe broad historical patterns rather than a timetable that applies to every species.

Read the Scientific Reports study: https://www.nature.com/articles/s41598-024-57109-8.

How quickly can a species reach Greece?

Southern Greece, especially Rhodes, Crete, and the southeastern Aegean, is one of the first European regions encountered by species expanding northwest from the Levant.

For a relatively mobile fish, reaching southern Greek waters can take roughly 10–15 years after the beginning of a successful, detectable expansion. Slower species may require several decades.

Lionfish provide a striking example. Genetic and observational evidence indicates that Mediterranean lionfish spread from the Red Sea through the Suez Canal, established in the Levant, and then expanded through Cyprus, Turkey, and Rhodes using a stepping-stone pattern. Their appearance across these locations over relatively short intervals demonstrates how quickly a suitable, mobile species can expand.

Read the lionfish study: https://www.nature.com/articles/s41598-017-07326-1.

Other organisms move much more slowly. The tropical seagrass Halophila stipulacea, for example, was first reported in Rhodes approximately 25 years after the Suez Canal opened.

Review its Mediterranean invasion history: https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.00300/full.

Why are some species much faster?

Several factors determine the speed of establishment and expansion.

Mobility and reproduction

Fast-swimming fish and species with widely dispersed larvae can cover large distances. Species that reproduce early, produce many offspring, or spawn several times per year can establish more rapidly.

Sea temperature

Many Suez migrants originate in warm tropical or subtropical waters. The eastern Mediterranean is warmer than the western and northern parts of the basin, making it easier for heat-loving species to establish there.

Continued warming can make areas farther north and west more suitable, although temperature is not the only controlling factor.

Currents and connected habitats

Ocean currents can transport eggs, larvae, and drifting organisms. Continuous rocky coastlines, seagrass beds, or other suitable habitats act as stepping stones between populations.

Unsuitable habitat can slow or stop expansion even when two locations are geographically close.

Shipping

Ships can transport organisms in ballast water or on their hulls. This can produce long-distance jumps between ports, allowing a species to bypass the slower process of natural coastal expansion.

Detection delays

The first scientific record is rarely the exact moment a species arrived. Small populations can remain unnoticed for years, particularly in poorly monitored areas. Reported expansion times therefore combine biological spread with differences in monitoring and detection.

A realistic Mediterranean timeline

A simplified scenario might look like this:

- 0–4 years: Passage through Suez and initial establishment in the southeastern Mediterranean.
- 5–10 years: Expansion along the Levant, Egypt, Cyprus or southern Turkey.
- 10–15 years: Arrival in parts of southern Greece for faster-moving species.
- Approximately 20–25 years: Expansion into the central Mediterranean around Sicily, Malta, Tunisia or southern Italy.
- 30 years or more: Wider expansion toward the western Mediterranean.

Ship-assisted transport could shorten these times dramatically, while unsuitable habitat or reproductive failure could prevent establishment altogether.

 Why early monitoring matters

By the time an alien species is abundant and widely recognized, eradication may already be impossible. Monitoring near the Suez Canal, the Levant, Cyprus, southern Turkey, and southeastern Greece can provide an early warning before a species expands across the basin.

Fisher observations, citizen-science reports, environmental DNA sampling, and coordinated regional databases can all help detect new arrivals sooner.

The central lesson is that the process is not always slow. A successful alien fish may establish itself in less than a decade and reach Greece within roughly 10–15 years. Expansion into the central and western Mediterranean usually takes longer, but shipping, warming seas, and highly mobile life stages can accelerate the journey.

Use the interactive simulation below to compare slow, moderate, and fast-spreading species and explore how habitat suitability and ship-assisted movement change the timeline.

Protecting wildlife is not always about large conservation projects or expensive infrastructure. Sometimes, one of the most effective conservation tools is simply providing the right information in the right place.

This week, Merman Conservation installed two new awareness signs at Liri Beach in South-east Pelion, Greece. Their purpose is straightforward: to inform visitors that they are entering an area used by the Mediterranean monk seal (Monachus monachus), one of the world's rarest and most endangered marine mammals.

Why Information Matters

Most people who visit the beach want to enjoy nature without causing harm. However, many simply do not know that monk seals may be resting, swimming, or using nearby coastal caves.

By making this information visible, visitors can make informed choices that reduce unnecessary disturbance before it happens.

The signs encourage everyone to:

• Keep a respectful distance if a seal is observed.
• Stay quiet and avoid unnecessary noise.
• Never approach, feed, or attempt to touch a seal.
• Keep dogs under control and on a leash.
• Avoid entering nearby sea caves that may be important resting or breeding sites.
• Refrain from flying drones over the area.

These are simple actions, but together they can significantly reduce human disturbance.

Prevention Is Better Than Reaction

Wildlife conservation often focuses on responding after problems occur. Yet prevention is usually more effective, less costly, and better for both people and wildlife.

Educational signs are a practical example of preventive conservation. They create awareness before disturbance occurs, helping visitors become active participants in protecting sensitive habitats rather than unintentionally harming them.

When people understand why an area is important, they are far more likely to respect it.

Every Visitor Can Contribute

The future of the Mediterranean monk seal does not depend only on governments, scientists, or conservation organisations. It also depends on thousands of everyday decisions made by visitors, swimmers, boaters, photographers, and local communities.

Respecting wildlife requires no special equipment or expertise. It simply requires awareness and consideration.

Action Is Better Than Doing Nothing

Installing two signs will not solve every conservation challenge facing the Mediterranean monk seal. However, doing something meaningful is always better than doing nothing.

Conservation is built from many small actions that work together over time. Every informed visitor, every respectful encounter, and every disturbance that never happens contribute to creating a safer environment for this remarkable species.

At Merman Conservation, we believe that conservation begins with knowledge. By helping people understand the wildlife around them, we create opportunities for everyone to become part of the solution.
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Sometimes, protecting one of the world's most endangered marine mammals starts with something as simple as reading a sign.

The first half of 2026 has already been an important period for the Greek Shark Logbook, with 40 shark observations recorded from 1 January to 30 June 2026.

These records do not show something “new” or unnatural happening in Greek waters. Sharks have always been part of the marine biodiversity of Greece and the wider Mediterranean. What is changing is that more people are now recording, photographing, and reporting them.
This is exactly why the Greek Shark Logbook exists: to collect verified observations, organise them in a structured database, and help the public, researchers, media and authorities better understand shark presence in Greece.

40 observations in six months.

From January to June 2026, the Greek Shark Logbook recorded observations from several parts of Greece, including the Ionian Sea, the Corinthian Gulf, the Saronic Gulf, the Aegean Sea, Crete, the Pagasetic Gulf, the Dodecanese, and northern Greece.

The records included nine shark species:

• Prionace glauca (Blue shark)
• Isurus oxyrinchus (Shortfin mako)
• Mustelus mustelus (Common smooth-hound)
• Hexanchus griseus (Bluntnose sixgill shark)
• Galeorhinus galeus (Tope shark)
• Carcharhinus plumbeus (Sandbar shark)
• Carcharodon carcharias (Great white shark)
• Scyliorhinus stellaris (Nursehound)
• Squalus blainville (Longnose spurdog)

The most frequently recorded species during this period was the blue shark, with 17 observations. This is not surprising, as blue sharks are naturally present in Greek waters and are often seen seasonally, especially when individuals approach coastal areas.

The second most recorded species was the shortfin mako, with 9 observations. Other records included smooth-hounds, sixgill sharks, tope sharks, and single observations of rarer or less frequently reported species.

More records do not automatically mean more sharks.

One of the most important messages from the 2026 data is this:
More observations do not necessarily mean that there are suddenly more sharks in Greece.

It often means that more people are noticing them, filming them, sharing them online, and reporting them to citizen science projects.

In the last few years, smartphones, social media, action cameras, fishing groups, and local news pages have made wildlife observations much more visible. A shark that may have gone unnoticed or undocumented 20 years ago can now be photographed, uploaded, and discussed within minutes.

This visibility is useful, but it can also create unnecessary fear when sightings are presented without context.

The Greek Shark Logbook helps separate observation from exaggeration. It allows records to be checked, organised and mapped rather than lost in social media posts, rumours or sensational headlines.

Fishermen are becoming more involved.

A very positive development is the increasing participation of fishermen.

Fishermen are often the first people to encounter sharks at sea. Their contribution is extremely valuable because they can provide practical information that is often missing from public posts, such as location, date, depth, fishing method, approximate size, condition of the animal, and whether it was released.

In the 2026 dataset so far, 20 out of 40 observations were linked to fishing activity. This shows how important the fishing community is becoming for shark monitoring in Greece.

This also follows a wider trend already seen in the Greek Shark Logbook: fishermen’s participation has been increasing over time, from 5.9% of records in 2024 to 15.8% in 2025 and around 20.7% so far in 2026.

This is a major step forward. When fishermen participate directly, the data become stronger, more accurate, and more useful for conservation.

Why does this matter?

Sharks are often discussed only through fear, attacks, or sensational media stories. In reality, they are part of the natural marine ecosystem, and many species are threatened or vulnerable because of fishing pressure, bycatch, habitat degradation, and slow reproduction.

For Greece, better shark data are important because they can help us understand:

• where different species are being observed,
• which species are appearing more often in public records,
• which areas produce repeated observations,
• how often sharks are caught, stranded or seen swimming near the coast,
• and how citizen science can support long-term biodiversity monitoring.

The Greek Shark Logbook is not only a sightings map. It is a growing evidence base.

From fear to knowledge.

Every shark observation should be treated carefully, but not with panic.
Seeing a shark in Greek waters does not mean that the sea is unsafe. It means that Greece still has important marine wildlife, including species that have existed in the Mediterranean long before modern tourism, social media, or news headlines.

The real challenge is not to create fear. The challenge is to collect better information.

For every observation, the most useful details are:

1. date,
2. location,
3. photo or video,
4. species if known,
5. estimated size,
6. condition of the animal,
7. and how it was observed.

These details help transform a simple sighting into useful biodiversity data.

A stronger network for Greek shark records.

The first half of 2026 shows that the Greek Shark Logbook is growing. More observations are being collected, more areas are being represented, and more fishermen are participating.
This is important for science, conservation, and public education.

Sharks in Greece should not be treated as monsters, rumours or clickbait. They should be recorded, studied and understood as part of the country’s marine biodiversity.

The message from the first half of 2026 is clear:
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Sharks are present in Greek waters, people are reporting them more often, and with the help of fishermen, citizens, and local communities, Greece can build a much stronger picture of its shark biodiversity.