Monday, 9 November 2015

Seagrass meadows – carbon sinks and fishery powerhouses

The most underappreciated of marine ecosystems, the humble seagrass meadow.

I might be biased, but seagrass meadows are just a little bit fantastic. Seagrasses are admirable in that they do a lot just by being themselves; they are the strong silent type, happy for their flashy coastal colleagues the coral reefs to get all the adoration, whilst they quietly continue in the background, churning out the next generation of baby fish, and sinking lethal dissolved carbon into the seabed. 

To borrow a rugby analogy, they are the second rows of the coastal seascape, working hard in the ‘engine room’ whilst it’s the ‘pretty’, ‘flashy’ backs that grab the headlines with their razzle-dazzle. Seagrass meadows are barely recognised on the world stage, and hardly ever make the front page news, but they are essential to our metaphorical team’s success, week in, week out.

Seagrass meadows provide carbon capture storage at rates up to 100 times greater than rainforests. One hectare (10,000 m2) of seagrass can support up to 80,000 fish, and produce up to 100,000 litres of oxygen per day. Put another way, in a recent Plymouth University study, seagrass meadows in the Mediterranean Sea were valued as contributing approximately €190 million per year to local fisheries.

The drawback for seagrass meadows is that they just aren't seen to be as sexy as coral reefs. However, with the passionate work of a handful of individuals we are looking to change that perspective. For example, here in the UK there are a couple of recently formed organisations championing the cause for seagrass meadows.

In the southwest of England there is a fantastic new venture called the ‘Community Seagrass Initiative’ being run out of the National Aquarium ( in Plymouth. Their CSI project covers the 191 mile stretch of coastline from Looe in Cornwall, to Weymouth in Dorset and is seeking to engage coastal communities with their local seagrass meadows, raising awareness and promoting conservation.

In Cardiff, Wales, one of the UK’s newest marine charities has also recently been born – Project Seagrass (, of which I am a proud founding member.

Project Seagrass is an environmental charity devoted to the conservation of seagrass ecosystems through education, influence, research and action. We’re here to communicate to you that seagrasses both locally and globally are under threat, and as such their capacity to act as both carbon sinks and fisheries powerhouses is being jeopardized by our actions.

So what are these threats? Anchoring and inappropriate moorings scar the seabed and uproot the seagrass; less seagrass equals fewer fish. Furthermore, coastal development, litter, pollution and waste can smother seagrasses reducing their access to the vital sunlight they need for growth; less seagrass growth equals less CO2 absorption.

Protecting seagrass helps to ensure food security and fights climate change. Some of our most iconic sea creatures live in seagrass; seahorses, sea turtles and sea cows all need seagrass meadows. Can you imagine a world without them?

Richard ‘RJ’ Lilley is a British seagrass scientist and science communicator. Follow Richard @rjlilley on Twitter. You can see more images of seagrass and learn more about his work by following @projectseagrass on Facebook, Twitter and Instagram. 

Thursday, 5 November 2015

Understanding climate, commercial fishing and fish

If you were to ask people what influences the abundance of fish in the sea, most would probably answer ‘commercial fishing’. While it is true that commercial fishing can deplete fish stocks, another important factor, the ‘environment’, or more accurately, environmental variability, is often overlooked as a determinant of fish abundance.

Atlantic cod  (Gadus morhua)

Certainly, when the environment is benign, commercial fishing, referred to as a ‘top-down’ control of fish abundance (think of fishing as a form of predation) can be the most important influence. However, when the environment changes and becomes unfavourable, the environment will become a key driver of fish abundance, and this is referred to as ‘bottom-up’ control. Understanding the interplay of bottom-up and top-down controls is vital for sustainable fisheries, and especially at a time of climate change and warming seas.

It is the phytoplankton and the plankton food web that determines the abundance of fish and all other creatures in the sea (

Stylised diagram of the plankton food web with respect to the herring, a fish that feeds upon plankton throughout its life. The arrows show the interconnections in the food web, ‘who eats who’, revealing the complexity and how it might easily uncouple.

The plankton live at the sea surface and their habitat is likely to warm due to anthropogenic climate change. More and more studies are now providing evidence that the plankton’s distribution, abundance and seasonality is altering as their habitat warms, uncoupling the marine food chain. In the North Atlantic ocean many of these studies have focused upon understanding the population dynamics of the cod Gadus morhua due to its commercial importance and history of population declines.

In the Northeast Atlantic, warm-temperate, pseudo-oceanic species of copepod have moved northwards by about 10° of latitudes over 48 years between 1958 and 2005 (52–62°N;10°W) as the sea surface has warmed, which is a poleward movement of 23.16 km per year ( Cold water species of copepod have retracted towards the poles and warm-water species have moved northwards. This movement of copepods has resulted in a 60% reduction in the preferred food of larval cod in the North Sea, the cold water copepod Calanus finmarchicus, affecting cod recruitment (the number of juvenile cod that survive to become adults).

Cod is also a cold water species and the North Sea lies at the southern edge of this fish’s distribution (

The thermal niche of the Atlantic cod (blue area) based on mean annual sea surface temperature (SST) during the period 1960 to 2005 and the probability of cod occurrence. Both observed (1960 to 2005, shaded bars, white text and arrows) and projected (based upon climate change scenario A2, 1990 to 2100, black text and arrows) ranges in SST are shown for Iceland (solid vertical lines) and the North Sea (dashed vertical lines), indicating that under climate change scenario A2, the North Sea becomes too warm for high numbers of cod such that it may be an unviable fishery.
So, not only are cod in the North Sea experiencing fishing pressure, but the warming environment is now exerting bottom-up control too, both through the food web and upon cod directly ( You might well argue that cod will just move northwards and so ‘all will be OK’. Unfortunately, it is not so simple as both the habitat (bathymetry) and temperature must be suitable. The North Sea is a shallow, nutrient rich sea and so supports a productive plankton food web. (Shallow seas, like nutrient rich upwelling regions, support the world’s most productive fisheries.) Northwards of the North Sea the ocean deepens and is less favourable for plankton and cod. Here, the shallow seas are restricted to continental shelves along the coast of Norway and surrounding Iceland. The next, large, favourable habitat for cod is the Barents Sea.

Cod feed upon crabs, lobsters and shrimps and in regions where cod have declined through overfishing, such as in the Northwest Atlantic, there has been a large increase in these decapods, which may be due to decreased predation pressure upon them (relaxation of a top-down control). In the North Sea, where cod have declined due to the combined effects of fishing and environmental change, decapods have also increased in abundance. Currently, the abundance of decapods in the North Sea is also influenced positively by warming; they produce more offspring when the sea is warmer and warm-water species have also invaded. And so, in the North Sea, the decline of cod and the warming environment may both be favouring decapods. In turn, this has ramifications for other species and the ecology of the North Sea; there are ‘winners and losers’ in this ecosystem (

Two recent studies of cod have again shed light upon how important the environment is as a driver of an animal’s abundance. These two studies are focused at the northern and southern limits of the distribution of cod in the Northwest Atlantic. Here, at the species’ southern limit in the Gulf of Maine, warming seas are reducing the abundance of cod ( In contrast, at the northern, cold boundary of the species’ distribution in Newfoundland, warming seas are having a positive impact upon their numbers through the food web ( Interestingly, these two studies also reveal that environment is a more important determinant of abundance than controls upon overfishing.

If the global climate and the sea surface continues to warm it does not mean that we will not experience some seasons and years that are colder than others. (Of course, due to the warmer baseline temperature, these colder years will not be as cold as they might have been in the past.) Again, using cod as an example, in these cooler years we may see an increase in cod abundance among populations that reside at the warmer edge of the species’ niche due to more favourable conditions (such as cooler conditions would create in the Gulf of Maine or the North Sea). In these circumstances, if we only consider commercial fishing activity to influence abundance, we may be lulled into a false belief that a fish stock is recovering due to effective fishery management strategies, only to find that we were wrong when the sea temperature increases again.

Ecosystems by their nature are complex with many linkages among the species they contain. Understanding the interactions among species, and how and why they change, which must include an understanding of the environment, is key to their sustainable exploitation. Consideration of environmental changes is absolutely necessary with regard to anthropogenic climate change. While there is no guarantee that setting quotas will enable a stock to resist adverse climatic conditions, an absence of regulation might well precipitate a stock’s collapse, or might cancel any short-term benefit of improved environmental conditions.

Dr Richard Kirby and Dr Grégory Beaugrand are plankton scientists interested in marine ecosystem dynamics and fisheries.

Monday, 2 November 2015

Plankton as indicators of ecosystem change

From the crabs on the seabed to the seagulls in the sky.

Angular crab larvae

I explained in my previous article why there wouldn't be any polar bears on the ice without any plankton at the sea surface. In this blog I want to begin to tell you how studying the plankton has helped to understand climate-induced changes in the North Sea, a productive marine ecosystem that once provided 5% of the total global seafood harvest. Here, a recent warming of this shallow sea has altered the ecosystem from the animals that live on the seabed to the the seagulls in the sky above, and these changes were first noticed in the plankton.

Analysis of long-term plankton samples collected in the North Sea by the Continuous Plankton Recorder Survey ( revealed that the number of decapod larvae, and particularly the larvae of swimming crabs, had increased in abundance since the mid 1980s. This increase appears to be related to temperature. Following warm winters there are more decapod larvae in the plankton than following cold winters, and as the North Sea has warmed since the mid 1980s the number of decapod larvae has increased. (As you can see from the correlation between sea temperature and decapod larvae in the graph below).

Analysis of crab larvae confirmed that not only had swimming crab larvae increased in abundance, but the North Sea had also been colonised by two warm-water species, the swimming crab Polybius henslowii and the angular Goneplax rhomboides ( Swimming crabs are a good food source for lesser black-backed gulls (especially, during the breeding season), and their numbers have increased following the increase in swimming crabs (

Swimming crab (Polybius henslowii)

A simple bioenergetic model produced by German scientists showed that the 22,000 individual lesser black-backed gulls in the most important breeding colony in the south-eastern North Sea consumed approximately 35 million swimming crabs annually (i.e. 1590 swimming crabs per individual gull) during the breeding period (

While the increase in swimming crabs may be good news for lesser black-backed gulls, the general increase in decapods in the North Sea suggested from plankton analysis may not be such good news for their prey species, such as bivalves and flatfish, which have both shown a decline in abundance as the number of decapod larve in the plankton have increased. The decapod megalopa larva is a voracious predator in the plankton and the newly settled decapods prey upon young bivalves and flatfish recruits on the seabed.

So, I hope that this small story shows how by studying the plankton, in this case the abundance of decapod larvae, we can not only detect early signs of change, but perhaps also understand how changes in the marine ecosystem may extend from the seabed to the skies above.

Dr Richard Kirby is a British plankton expert, scientist, author and speaker. Follow Richard @planktonpundit on Twitter. You can see more images of plankton and learn more about them in Dr Richard Kirby’s book “Ocean Drifters, a secret world beneath the waves” available on Amazon and as an iBook.

Friday, 28 August 2015

The evolution of whales

Whales, dolphins and porpoises, collectively known as cetaceans (for their classification in the mammalian order Cetacea) have long captured the attention of humans. From early drawings etched on the walls of Paleolithic caves, to 21st century satellite tags tracking the underwater movements of these denizens of the deep, the lives of humans and whales have been inexorably entangled. This connection has been a compelling story of the discovery and scientific study of large, charismatic sea animals tempered by darker times of intense human hunting and whaling that left many species hovering on the brink of extinction.

The approximately 90 living species of cetaceans inhabit nearly every ocean basin in addition to a few river systems, occupying diverse habitats that include polar, temperate and tropical waters. Whales evolved more than 50 million years ago in present-day India and Pakistan. Evidence from anatomy as well as genetics supports a close relationship between whales and even-toed ungulates (e.g. deer, giraffes, hippos, pigs, cows) with hippos positioned as their closest kin. The land to sea transition made by whales involved anatomical and physiological adaptations (e.g. feeding, locomotion and respiration) that are well represented in the fossil record. For example, recent discoveries indicate that the earliest whales like their terrestrial ancestors had well developed fore and hind legs and lived on land as well as the water.

One of the best-documented examples of evolutionary change in the fossil record is the loss of hind limbs in whales and recent study of whale embryos has revealed its genetic basis.

Whales are divided into two major groups: odontocetes (toothed whales) and mysticetes (baleen whales). Odontocetes are more diverse with 76 living species compared to 14 species of mysticetes. As the name suggests odontocetes possess teeth and most eat fish although some have very reduced dentitions and are specialized for suction feeding squid.

A key adaptation that enables odontocetes to pursue prey involves using high frequency sounds produced in the nasal region.

Mysticetes do not echolocate and recent research suggests that they may find prey using sensitive vibrissae (whiskers) on the rostrum. Although mysticetes possess teeth at birth (also present in early fossil mysticetes) they are resorbed and adults feed using baleen, keratin based structures. Plates of baleen are suspended in racks from their enormous mouths that act as a comb to bulk filter feed large aggregations of fish and zooplankton.

The biology of whales has been enriched by remarkable recent advances in integrated research in paleontology, ecology, behavior, and genetics. Modern techniques such as attaching digital acoustic tags (DTAG) to whales have elucidated extraordinary feeding behaviors and foraging strategies. Not only do these tags provide information on body orientation (i.e. acceleration, pitch, roll and heading) they also record sounds made by and heard by the tagged whale as well as recording environmental parameters such as water temperature and depth. Isotope studies reveal ocean temperature changes through time providing evidence that the diversification of modern whales was associated with increased food production.

Exciting breakthroughs in understanding the anatomical structures and pathways involved in sound production and reception in whales have been facilitated by CT scans and 3D imagery. Genetic and genome studies have explored evolutionary relationships among cetaceans as well as providing valuable life history and population data critical to the development of thorough management and conservation plans.

Knowledge of the biology of whales provides a framework that is essential for helping us understand how best to protect and conserve them. Further, as top predators, whales are indicator species of the health of the ecosystem and serve a vital role as sentinels of climate change.

Beautifully illustrated throughout, “Whales Dolphins and Porpoises” edited by Annalisa Berta, combines highlights from the latest scholarly studies of the nature and behaviour of the world’s whales, dolphins and porpoises, with a fully comprehensive species directory, that offers detailed profiles of each species alongside all the information needed to identify them in the wild.

Annalisa Berta has been Professor of Biology at San Diego State University, California, for more than 30 years, specialising in the anatomy and evolutionary biology of marine mammals. Past President of the Society of Vertebrate Palaeontology and co-Senior Editor of the Journal of Vertebrate Palaeontology, Berta has authored and co-authored numerous scientific articles and several books for the specialist and non-scientist.

Edited by Annalisa Berta
Available 21 September 2015
ISBN: 978-1-78240-152-0

Wednesday, 10 June 2015

Are we winning the battle to save sea turtles?

We have come a long way since early conservationists started with many beleaguered nesting sea turtle populations in the middle to the late part of the 20th Century. Nesting turtles are now protected in many countries around the world, there are now very few large legal harvests, and many populations, such as the one we study in Ascension Island have begun to recover incredibly well.

Leatherback sea turtle released from fishing net. Pic: Tim Collins, WCS

I feel that the level of awareness of sea turtle conservation and goodwill towards this charismatic animal group is at an all-time high. This is down to a tremendous cadre of people (many thousands) who work tirelessly for turtles across the globe. Sea turtles are a good news story and cause for ocean optimism. There is, of course, still work to be done.

The challenge now, is to look after turtles in the sea as the main threat to sea turtles is in incidental capture in fisheries (bycatch). There has been much focus on large-scale driftnets, longlines and trawlers and a great deal of progress made. Recently it has become ever more apparent that because of where they operate and their very large numbers that coastal and inshore fisheries are responsible for very high levels of bycatch. It may be that each vessel does not catch many, but when scaled up their impact can be substantial e.g. in Peru.

Illegal trawlers in Conkouati-Douli National Park.  Pic: Tim Collins, WCS

To effect change, however, fishers need to be engaged in the process. As a case in point, I outline a current Darwin Initiative Project we are supporting in Conkouati-Douli National Park in the Republic of Congo, Central Africa. The park plays host to important populations of elephants, chimpanzees and lowland gorillas but also has important aggregations of nesting olive ridley and leatherback sea turtles and humpback dolphins. These are co-located with impoverished people living in coastal areas who have high degree of fisheries dependence and limited alternative livelihood opportunities. There is a modest degree of turtle bycatch, but perhaps of greater concern is the much larger effort associated with unregulated trawl fisheries who are a source of conflict with the artisanal fishers and has an, as yet, unassessed impact on marine turtles.

Fishermen in Conkouati-Douli National Park. Pic: Tim Collins, WCS

Using a participatory approach, artisanal fishers are volunteering to carry GPS trackers to map their activities in high resolution, allowing us to assess their footprint, possible bycatch interaction hotspots and integrate their needs into future marine spatial planning for marine protected areas that can have maximum benefit to biodiversity (and ultimately fisheries as a result of spillover) with minimal cost to stakeholders. These data will hopefully feed into the development of a marine plan similar to that in neighbouring Gabon, which is also of global importance for marine turtles, which has recently announced a new network of marine parks that will comprise 23% of its EEZ.

Olive ridley sea turtle in Conkouati-Douli National Park. Pic: Brendan Godley

Although the well demonstrated threats of direct take, habitat loss and degradation may still be of concern to some populations, and we must consider emerging threats such as climate change and marine plastic pollution, artisanal and small scale fisheries is the key area on which I believe we must focus our efforts. A more coherent ecosystem based approach is undoubtedly important. Moreover, progress in this regard is crucial to sustain the livelihoods of many millions of coastal people who are so dependent on the sea for nutrition and employment. 

Brendan Godley is the Professor of Conservation Science/Director of the Centre for Ecology & Conservation at the University of Exeter. Follow Brendan on Twitter @BrendanGodley

Wednesday, 20 May 2015

Deep-sea sharks in danger

The dark, cold, crushing depths of one of the world’s largest ecosystems is home to about half of all known shark species. However, living at depths between 200-3000m, these deep-sea species aren’t your typical sharks. Armed with sharp defensive fin spines, large reflective eyes, and, in some cases, an ability to glow in the dark, these alien sharks could be the stars of a science fiction horror movie. But with a biology specifically adapted to deep-sea living, the sharks themselves may be the ones who experience the horror, as fisheries move ever deeper into their deep-sea world.

Portuguese dogfish  (Centroscymnus coelolepis) Pic: Alan Jamieson

If you watched the latest BBC “SHARK” trilogy, you will have seen cameos from the Greenland shark, Frilled shark and Goblin shark. Using new technologies the BBC was able to capture some truly revolutionary footage of these enigmatic creatures. But just as they have begun to whet our interest, they are becoming increasingly threatened by an expanding fishing industry. The very features that make these sharks successful deep-sea predators have ironically made them vulnerable to man and his ships.

Longnose velvet dogfish (Centroselachus crepidater)

Life in the deep-sea is challenging due to the lack of baseline nutrient production. Instead, the deep-sea must rely on the transport of nutrients from surface waters to fuel their food webs. Put simply, food down here is quite scarce. To survive down here, sharks have had to adapt.

Like most other deep-sea fish, the deep-sea sharks have a very low metabolism. One theory behind this is that due to the lack of light, there is no need to be a fast active predator [1]. Chasing down prey is too risky and energy demanding. When feeding events are rare and often opportunistic, it makes sense to have a biology that inherently conserves energy. Furthermore, these sharks are slow-growing and long-lived. Some scientists estimate that the Greenland shark can live in excess of 100 years [2].

Velvet belly lanternshark (Etmopterus spinax)

The way these sharks reproduce also has a substantial effect on their vulnerability. Deep-sea sharks tend to reach maturity at a much later age than shallower water sharks, have fewer offspring and have long reproductive cycles. The Leafscale gulper shark could almost star alongside Steve Carrell in the 40-year old virgin movie, as it is believed it doesn’t reach sexual maturity until 35 [1]! Investing more energy into producing fewer, large, developed offspring, females maximize the chances of their pups surviving in this challenging deep-sea world.

To handle the crushing pressures of the deep, these sharks have very large oily livers, which they use for buoyancy. In order to maintain such oily livers, it is important to feed regularly [3]. Deep-sea sharks literally face the risk of starving or sinking to their death if they don’t feed often enough. Therefore, deep-sea sharks don’t stray too far into the deep, where food is even scarcer and subsequently are rarely found below 3000m.

Leafscale gulper shark (Centrophorus squamosus) Pic: Joao Correia

Unlike pelagic and coastal sharks that are targeted mainly for their fins, deep-sea sharks are targeted for their large livers. Squalene, a main component of shark liver oil, is used in a wide range of items including face creams, dietary supplements, vaccines and a variety of medical products, and it can fetch a high price in many markets.

It’s almost the perfect storm in terms of an animal’s vulnerability to fisheries. Having large livers, slow metabolism and specific behavioural traits, these sharks have become top deep-sea predators. But with fisheries targeting them for these livers, and a biology that means population recovery is slow, these deep-sea sharks are clearly under serious threat. Whilst Europe has recognized this and prohibited the landing of any deep-sea shark, the rest of the world has yet to follow suit.

We are still trying to unravel the mysteries of many of these alien ecosystems and assess the impact that continued exploitation will have. We are in grave danger of not only never seeing these fascinating sharks in future wildlife documentaries again, but also losing them from our oceans completely before we have fully understood their importance to the planets health. 

1: Rigby, C. & Simpfendorfer, C. Deep-Sea Res II, 115, 30-40 (2015)

2. MacNeil et al. J. Fish. Biol. 80, 991-1018 (2012)
3 Musick, J. A. & Cotton, C. F. Deep-Sea Res. II. 115, 73-80 (2015)

Christopher Bird is a Ph.D student at the University of Southampton and The National Oceanography Centre. Having worked with many shallow water sharks during his early education, he is now dedicating his research to understanding the trophic and spatial ecology of deep-water chondrichthyans in the Northeast Atlantic. Follow Chris on Twitter @SharkDevocean & blog

Monday, 13 April 2015

In the company of dolphins

The Moray Firth and North East coast of Scotland are home to a resident population of bottlenose dolphins, around 200 or so in number and I am fortunate to spend my working life studying and photographing these big, charismatic predators.

Bottlenose dolphins in the Moray Firth

A boat is not always necessary to get access to these dolphins, as they can hunt for seasonal migratory salmon only a few metres from the shore of one particular peninsula – Chanonry Point on the Black Isle near Inverness. I am able to monitor which individual dolphins are using the area by recognising them through their very individual dorsal fins – a technique called “mark recapture”. I often share these pictures and data with my friends at Aberdeen University’s Lighthouse Field Station at Cromarty who run the official Photo ID project.

"Mark recapture" of bottlenose dolphin dorsal fin

These dolphins are also highly individual in nature, not just in dorsal fin appearance and have very distinct personalities that you get to know when you study them for an extended period – we are talking decades here as these are long-lived mammals – 50 years or so for females isn't uncommon. I have the honour of having a young male dolphin named after me ID#1025 “Charlie” who is the son of “Kesslet” whom I have studied for 20 years. The work that I do for the charity Whale and Dolphin Conservation (formerly WDCS) is to study 6 individuals in particular that the public can “adopt” and support us financially, constantly supplying my support team at head office with the raw ingredients to keep the programme going. It might sound all very romantic, studying dolphins for a living - but up here in northern Scotland it can be hard, arduous work, especially in the winter when the weather is challenging and the dolphins are farther out to sea hunting winter prey like herring.

Bottlenose dolphin and salmon

To photograph these dolphins from the shore I use some of my professional photography “toys” to get as good images as I can. You will see me throughout the year standing at Chanonry Point with my huge white Canon 500mm lens and high frame rate IDX camera body mounted on a big carbon fibre tripod getting pictures of the dolphins and observing their behaviour as they move in and out of the area. If I am lucky enough to get out with Aberdeen University or maybe one of the local tour boats in good weather then I can top up my image bank of dolphins out at sea using much smaller zoom lenses. When out on the Moray Firth I can come across individuals that I might not encounter around Chanonry very often as some of these dolphins have their own favourite areas and might not visit my “office” that frequently. It's great fun catching up with other dolphins that I haven’t seen for a while, especially the females if they have had new babies. Although I have been doing this for a long time now, I still feel my heart-rate increasing whenever I see a dorsal fin and I never get tired seeing them – I just love being in the company of my dolphins.

Charlie Phillips at his "office" on Chanonry Point

Charlie Phillips is an award-winning professional wildlife photographer, lecturer, and author who was Scottish Nature Photographer of the Year 2012. He is also Field Officer for marine mammal charity WDC. Follow Charlie @adoptadolphin on Twitter. Charlie's new book “On a Rising Tide” is available now from