Sea Anemone (Cribrinopsis fernaldi).  Photo by  Aaron Baldwin.


Philip Lambert


In the darkened hall a slide projector hums in the background and the glow from the screen reflects off the faces of a rapt audience.  As each new image appears there are murmurs of recognition interspersed with gasps of amazement. After years of giving slide shows about the colourful underwater life of British Columbia it still thrills me to hear those reactions.  But it also concerns me that much of the life that inhabits the fertile waters of B.C. is for most people, "out of sight out of mind".  A recent book on biodiversity (Wilson, 1988) contains 57 chapters on the subject. Of these, only 2 deal directly with the marine environment. Does this mean that the loss of diversity is not a problem in the sea?  Is it a case of lack of data or are we simply dealing with the more urgent terrestrial and fresh water problems first?  I suspect it is a little of each.

In the following pages I will describe the rich diversity of marine invertebrates in British Columbia,  how it compares with other temperate regions, and speculate on why these waters teem with life.   What is the present state of our knowledge and, finally, what are the threats to this rich marine diversity.

Water Flea (Drepanothrix dentata).  Photo Royal BC Museum.

Species Diversity

I can usually impress an audience with a list of record-sized marine invertebrates from the west coast, that Guinness would envy - the largest chiton in the world, the largest octopus, the largest sea slug, the heaviest sea star, the biggest barnacle. I can also boast 68 species of sea stars, over 600 amphipod crustaceans, 75 sea anemones and their relatives, 478 species of polychaete sea worms and 111 species of nudibranchs, and the list goes on.  The west coast of Canada is generally recognized as being exceedingly rich in marine species when compared to other temperate regions in the world. In Table 1 I have summarized the numbers of species in some invertebrate groups in B.C. compared to elsewhere. 

It is difficult to find comparative figures for all invertebrate groups in each geographic area and the data vary a great deal as some are taken from old literature, some from scientific papers, and others from popular books.  Nevertheless,  the data show the richness of British Columbia waters. I have made the figures more comparative by calculating the number of species (shown in brackets) per degree of latitude.  For most groups, B.C. comes out on top, in diversity of species.

Animals without backbones, the invertebrates, are estimated at about 6,555 species in B.C. (Austin, 1985). Compare this with the much better known vertebrate groups - 400 fishes, 161 marine birds and 29 marine mammals (Cannings and Harcombe, 1990) and it is obvious that marine invertebrates make up a major portion of our marine animals, in fact 92 %, based on these figures. If we add to this all the undocumented species and there are probably many, this figure would be well over 95%.  The point I would like to make here is that although invertebrates make up 95% of the animal kingdom, it is that other 5% that traditionally gets most of the press.

Common Featherstar (Florometra serratissema). Photo by Aaron Baldwin.

State of Knowledge

Investigations of biodiversity in the ocean are hampered by our sampling methods. For the most part we still drop a bucket down on the end of a long wire and blindly drag it along the bottom, pulling it up to see what we accidentally captured. In shallow areas we now have the use of SCUBA for studying the flora and fauna directly but even then our stay is brief because of the limitations of our air-breathing physiology.  Generally, our knowledge of an area is directly related to its proximity to population centres. Regions that are easy to get to are studied first with outlying regions left for the occasional expensive collecting trip.

Taxonomic experts usually limit themselves to one group of invertebrates. Thus, our knowledge can be detailed for one taxa and poor in others depending on the interests of the scientists that have worked in a geographic area. For example, Dr. McLean Fraser, former Director of the Pacific Biological Station was world renowned for his taxonomic work on a group of colonial animals called hydroids.  Crabs and their distributions are well known through the work of Dr. J.F.L. Hart. Whereas other groups like sea cucumbers still need a lot more taxonomic revision and documentation before we can say we know them well.

Dire Whelk (Lirabuccinum dirum). Photo by Aaron Baldwin.

TABLE 1 - Numbers of species in each taxon from various temperate regions of the world.



48 to 55°


42 to 60°


35 to 45°

Brit Is

50 to 60°

New Zeal. S

42 to 50°



133 (26)

89 (5)




313 (5)


Crabs (Brachyura)

35 (5)

14 (1)

53 (5)

67 (6)

59 (7)

Sea Lice (Isopods)

100 (14)

75 (4)

51 (5)

80 (8)



81 (12)

60 (3)

38 (4)

41 (4)



478 (68)


327 (33)


Sea anemones

75 (11)


56 (6)

73 (7)



149 (21)

50 (3)

250 (25)


Sea slugs (Nudibranchs)

111 (16)


98 (10)

134 (13)


Sea squirts (Tunicates)

55 (8)


48 (5)

60 (6)

76 (10)

Sea stars

68 (10)


42 (4)

50 (5)


Moss animals (Bryozoa)

81 (12)


127 (13)

81 (8)

132 (17)

The data in brackets represent the numbers of species per degree of latitude. Sources - Numbers of species from selected temperate regions of the world. Data in brackets = numbers of species per degree of latitude. Sources - (1) Austin 1985, (2) Bennett 1964, (3) Bousfield 1981, (4) Butler 1980, (5) Gordon 1986, (6) Gosner 1971, (7) Hart 1982, (8) Ingle 1980, (9) Lambert 1981, (10) Manuel 1981, (11) Millar 1970, (12) Millar 1982, (13) Mortensen 1977, (14) Naylor 1972, (15) Rafi 1985, (16) Ryland & Hayward 1977, (17) Shih 1977, (18) Smaldron 1979, (19) Squires 1990, (20) Thompson & Brown 1976.

Origins of Biodiversity in British Columbia

There are several possible explanations for the richness of the marine fauna in British Columbia.

 1) the Pacific basin is older geologically than the Atlantic. As a result species have had time to evolve and diversify. Sea stars, for example, number 68 species on this coast versus 42 on the east coast U.S.

 2) Water temperatures are generally milder here than on the east coast of Canada. Our average water temperature in winter is 6-8 ° C and the intertidal zone seldom freezes.  In the Maritimes the water temperature hovers around 0 ° C and the intertidal often freezes.  Fewer species can survive those harsh conditions.

 3) Our coast is also physically very diverse. Hundreds of inlets penetrate into the coast range, many of them deeper than the adjacent continental shelf. Thousands of islands break up the twice daily tidal flood, creating strong currents that stir up the nutrients brought down by the rivers and streams. On the western edge of the continental shelf upwelling, during the summer months, brings nutrient-rich waters to the surface. Blooms of phytoplankton provide a kick start for the rest of the food chain that our commercial fisheries depend on.  Each kind of habitat harbours different sets, or communities, of marine invertebrates, thereby adding to the overall richness of the coast.

Opalescent Nudibranch (Hermissenda crassicornis)
Photo by Aaron Baldwin.

Barkley Sound

Barkley Sound on the west coast of Vancouver Island is a microcosm of these rich marine habitats.  Austin et al (1982) listed 1500 species of marine invertebrates there, excluding bacteria and other microorganisms.  Some of the main groups (# of species) include:

Sponges 88
Coelenterates 150
Echinoderms 85
Tunicates 50
Bryozoa 105
Molluscs 180
Annelids 183
Crustacea 355
Other 85
Total 1481


The richness of the fauna is closely correlated with the variety of habitats found here.  Exposure varies from direct ocean swells to protected inlets and the diversity of substrates includes mud of channel bottoms, rocky intertidal, sand beaches, sheltered bays, eel grass beds, kelp beds, subtidal reefs, surge channels, gravel and boulders. Each of these substrates is preferred by a specific community of animals that are often limited to that habitat. As we shall see later, loss of habitat is the primary cause of species loss.

Deep Sea Cucumber (Scotoplaanes globosa). Photo Royal BC Museum  (Phil Lambert).

Strait of Georgia

The semi-protected waters of the Strait of Georgia support a slightly different community. Sediment makes up seventy-one percent of the bottom between 50 and 300 metres depth.  Burrowing invertebrates(infauna) such as sea cucumbers, clams, heart urchins, polychaetes and brittle stars dominate this habitat.  The infauna species tend to vary according to the sediment particle size.  The diverse fauna of shallow mud-flats and their role in the lives of vertebrates will be dealt with in a later section.


Hundreds of fiords that slash through the coast range of mountains present a third major grouping of species.  The rocky, steep sided shape of the inlets limits the animals to those that can attach to solid rock or withstand a rain of sediment. Tidal currents are light because inlets are uniformly deep. As a result, animals that can filter large quantities of water to extract their food seem to do quite well here. I have seen cloud sponge specimens as big as a small car, boot sponges five feet long and slender white organ-pipe sponges suspended out from a vertical cliff in the still, dark waters of Jervis Inlet. Brilliant red sea fans reaching three feet in height project from a vertical precipice. They could have been growing there for hundreds of years.

 Some mid-water animals like eel-pouts are reminiscent of deep sea species. In fact, many of the mainland fiords are much deeper (Jervis Inlet is 1100 metres) than the adjoining continental shelf, at less than 200 metres.  Gorgonian sea fans, common on the walls of some inlets, are not usually collected again until we sample in deep water off the continental shelf. Glass sponges, normally associated with polar or deep seas, are also common in fiords.  Tube worms, sponges, brachiopods, cup corals, gorgonian sea fans, anemones, and squat lobsters are some of the dominant organisms on the vertical rock walls. Levings et al (1983) summarize the flora and fauna of the Strait of Georgia and connecting inlets.

Mud Glorious Mud

Within the Strait of Georgia, to a depth of 20 metres, mud and sand make up 832 km2 or 66.8% of the area between high tide and 20 m.  Rocky shores only contribute 25.7 % (Levings et al., 1983).  Within the Fraser River Estuary system alone there are 500 km of shoreline, most of it highly productive mud.  Estimates of biomass for the 14,000 hectares of Sturgeon and Roberts Bank, the main mud flats on the outer shores of Lulu Island are shown below (Levings, unpublished data):

• vascular plants(eel grass) 1320  kcal/m2
• microbenthic algae (diatoms) 65
• benthos ( inverts in mud)  40
• phytoplankton (in water) 15
• zooplankton & surface inverts 0.6

These data show that plants make up by far the greatest bulk of living material on the mud flats.  So what is the significance of all this mud?  Estuaries and mud flats are often described as extremely important and productive habitats.  A brief description of the organisms and processess in this microhabitat will help to explain this productivity (Fenchel, 1969).

Oxygen penetrates only a few centimetres into this type of mud. Below these oxygenated layers, all production is in anaerobic, sulphide-containing layers. Bacteria, the most important organisms in these anoxic layers, decompose the organic material in the absence of oxygen and convert it to low molecular weight molecules (H2S, NH3, CH4, H2). These compounds then diffuse upwards to be oxidized by other types of bacteria in the oxygenated layer.  Different types of bacteria in each layer help to convert the organic molecules into living tissue.  The bacteria themselves are then consumed by other animals such as nematodes or ciliates. In intertidal and subtidal sediments, the numbers of bacteria at the surface have been estimated at up to 17,000,000,000 per cubic cm., the numbers decreasing with depth (Rublee, 1982). They are also more numerous in late fall when algae and other plants die off and fall to the bottom.

Two groups of animals, nematode worms and ciliates, prey on these bacteria.   Nematodes tolerate anoxic conditions and form a vital link between the decomposing organic material below the surface and the next step in the food chain.  "Nematodes are probably the most abundant metazoans in the biosphere..." (Heip,Vinx and Vranken, 1985). Even using sieves of 50 μm mesh size greatly underestimates the nematode numbers. Near the high tide mark in salt marshes, nematode numbers have been recorded up to  5,000,000 individuals per sq.m.  Within this mud they feed on bacteria, microalgae, detritus and other nematodes, polychaetes and oligochaetes.

The number of species of nematodes is very poorly known.  It is likely that the number of species, if we only knew, is probably much higher than any other metazoan group.  A recent review counted a total of 735 nematode species in the North Sea. It is not uncommon to obtain 50 species or more in a single 10 cm2 core. A study done in an intertidal area found 70 species, 31 of which were in the oxic upper layers, 29 extended down into the suboxic intermediate layer and 8 species were exclusively in the black anoxic layer (Heip, Vincx and Vraken, 1985).  Even these microscopic animals have been found to be quite selective in what they ingest. Their mouth parts are specialized for certain shapes of prey.

Nematodes are of major energetic importance in littoral ecosystems, forming a significant part of the diet of many other animals (Platt and Warwick,1980).  Nematodes and ciliates make up the bulk of the meiofauna (a group of microscopic organisms that live between the rains of sediment). Meiofauna are highly modified forms from a variety of invertebrate taxa including nemertean worms, gastrotrichs, kinorhynchs, bryozoa, gastropods, brachiopods, polychaete and oligochaete worms, ostracods, and tardigrades.

Single celled ciliates are also of major importance in estuarine sediments. They have been estimated at up to 20,000,000 per sq m. Like nematodes they prey on bacteria and also on benthic diatoms, blue-green algae, and flagellates. 

In the estuarine mud, copepods are, numerically, the next most important group after the nematodes.  Unlike the pelagic swimming forms, they are reduced in size and have lost their swimming appendages. The harpacticoids are the most common of the bottom-dwelling (benthic) copepods and form the basic food resource for small and juvenile fish in estuaries (Gee, 1989).

The meiofauna forms the basis of the benthic food chain.  It is this food chain coupled with the photosynthesis of the plants that creates the productivity of this ecosystem.  Many of these organisms become food for mud eaters like sea cucumbers and lugworms. As the animal takes in large quantities of mud these small animals are digested along with any other organic material. It is difficult to determine how many are eaten because there are no hard parts or recognizable remains that can be observed in gut samples. Thus, the role of these microscopic forms in the energetics of mud flats have been underestimated in the past.

Fish and Bird Food

Only a small proportion of the eel grass on a mudflat is consumed directly by herbivores like sea urchins or Black Brandt.  The majority of it decomposes and the energy is subsequently transferred through the meiofauna, to small crustaceans, and then to juvenile fish and larger filter-feeding invertebrates.  Small bottom-dwelling crustaceans such as amphipods, harpacticoid copepods, isopods, mysids, cumacea, shrimp and juvenile crabs provide the main diet of juvenile fish and many birds.  Unlike planktonic crustaceans that harvest living phytoplankton and are eaten by carnivores in a rapid, direct transfer, these benthic, detritus-based food webs are more complex and slower in transferring the energy up the food chain. This has a "slow-release" effect which serves to reduce fluctuations and stabilize the food supply.   When the eelgrass dies back in the fall, the decomposition process described above takes over. This delayed action provides food for fall arriving birds and other winter users of the estuary.  So it is this two-pronged flow of energy from photosynthetic organisms to herbivores followed by the decomposition cycle that yields the high productivivty of mudflats.

A study in two bays near Nanaimo showed that pink salmon fry fed primarily on benthic harpacticoid copepods, juvenile stages of copepods and barnacle larvae. Fry consumed 6 to 13 % of dry body weight every day (Godin, 1981).  In the Fraser estuary, juvenile Chinook salmon consumed a total of 48 taxa of invertebrates but 10 taxa made up 95 % of prey (Levings, Conlin and Raymond, 1991).  Prey included oligochaete worms, harpacticoid copepods, amphipods, mysids, fish larvae, aphids and chironomids.  These latter two taxa show the great importance of the marsh areas along the fringes of the estuary as habitat for foraging juvenile salmon.  These data provide good arguments against reclamation projects which fill-in fringing marshes.  Numerous studies have documented the value of estuaries in the life cycle of salmon species.  Unfortunately little data exist for non-commercial species of fish which make up the bulk of fishspecies.

Perhaps the most high profile users of mudflats are birds.  Over 130 species from more than 20 countries and 3 continents breed, migrate or spend the winter in the Strait of Georgia (Butler and Vermeer, 1989).  In summer many birds feed directly on the plants and seeds of the mudflats and adjacent marshes, while wintering birds rely on the benthic organisms that peak later in the year following the decomposition cycle described previously.  Either way, the significance of the Fraser delta to birds cannot be overstated.  Between the Copper River delta in Alaska and the wetlands of California, the Fraser delta is a vital link where migrating birds can stop and refuel in preparation for the next leg of their journey (Butler and Campbell, 1987). Competition for space between humans and wildlife shows up in the figures for area of marsh that is now behind dikes - 75% of marshes in the Fraser delta and 32% of estuarine marshland on Vancouver Island (Butler and Vermeer, 1989).

Loss of Mud Habitat

Every time we dredge a shallow channel or bay, we lose a few more acres of this valuable, productive sea bottom from the ecosystem.  Channels of the Fraser River are kept open for freighters by dredging,  Ganges Harbour has a dredged channel, as does Squamish and many other harbours.  Most marinas are situated in shallow bays, some have been dredged.  The boats and floats cut out sunlight which would normally enrich the productivity of the shallow mud. It is ironic that in order to attract sports fishermen to an area, marinas are built and dredged and in so doing may sacrifice the very habitat that supports juvenile salmon.  In Victoria harbour certain sediments are so heavily polluted with lead, mercury, cadmium and PCB's from previous industrial sites that it cannot be moved for fear it will poison other parts of the ocean floor (MacDonald, 1991).  In parts of Esquimalt Harbour sediment had the third highest levels of cadmium and mercury on the Pacific coast.  These examples are a legacy of our past habits. Only recently have regulations become more stringent and better enforced.

Historically most cities and towns were established around harbours on sheltered bays.  On the Lower Mainland small tributaries of the Fraser River have evolved from productive, pristine streams in the 1800's to little more than drainage ditches today.  This has happened slowly over the years, so slowly that generations have barely been aware of these changes.  That's how it happens.  Each time someone proposes to fill in a marsh, the public reaction is often - "how could one acre make a difference?"  Even the diking of areas around the Fraser Delta to create more farmland for cows or crops is "robbing Peter to pay Paul".  In terms of the amount of living material produced per square metre (productivity), estuaries are twice as productive as the richest farmland.  But because this production is hidden among the weeds and marshes, it seldom registers in peoples minds as being important.  "If only it were possible to make bread out of river estuaries, people might realize their value"(article in Vancouver Sun Jan.4, 1975).  Diking reduced the number of salt marshes where insect larvae and plant material provided food directlyand indirectly for salmon and other fish. 


It is also ironic that the fertility of the delta resulted from regular flooding by the river in ages past.  Dykes now prevent flooding.  This natural replenishment of nutrients has been replaced by the application of artificial fertilizers made from non-renewable resources.   Excessive use of fertilizers can cause an imbalance in nutrient ratios and an over-enrichment (eutrophication) of the waters receiving the run-off.  Marine pollution, including eutrophication and sedimentation from coastal run-off, may outweigh harvesting, habitat destruction, species introductions, atmospheric effects, and climate change as a threat to biological diversity in the oceans (Eiswerth, 1990). Such man-made eutrophication has already been documented for the Baltic Sea, North Sea, Adriatic Sea, parts of coastal India, and the Black Sea (Patin, 1985; Mee, 1992). Granted, most of these examples are in poorly flushed basins. But if the volume of effluent is great enough, even our relatively well-flushed water bodies could be taxed to their limit in time.  In many areas of environmental health history has shown that what was once considered a safe level can be re-assessed with new data, and later considered to be a health risk (eg. smoking, asbestos, radiation, PCBs, heavy metals etc.).  The population emptying wastes into these waters is increasing at an alarming rate, but the water body remains the same. In 1973 there were 85 marine discharge permits issued for B.C.  In 1988 the number of permits had risen to 393.  In 1986 the province issued an additional 245 permits for waste discharge into the Fraser River Basin which eventually empties into the Strait of Georgia Basin.  Of 41 municipalities discharging sewage into the Fraser System, 81% have only primary treatment (Kay 1989).  The sea is not an infinite sink and sooner or later the input will be more than the system can deal with or carry away.  And where is 'away'?  The open ocean?  Already chemicals like DDT and PCBs have been detected in remote parts of the ocean, and on land.  The public must demand long term vision from the decision-makers of today.

The Effect of Pollution on Biodiversity

Pollution in its many forms tends to reduce the diversity of an ecosytem. Species which cannot tolerate the toxins, chemicals or extreme conditions either die, leave the area or fail to reproduce successfully. With few predators, a handfull of tolerant species can become very abundant. This situation is contrary to a healthy system. An ecosystem with a diversity of species is more resistant to normal stresses. In the same way, an investor puts his money into a range of stocks from low to high risk, to protect himself from disastrous losses in a few stocks.

This reduction of diversity has been documented for a number of sites along the coast.  Species diversity near the disharge of a molybdenum mine in Alice Arm was lowest but improved with distance from the source (Brinkhurst et al, 1987).  This was after only 18 months of disharge. Four years after cessation of disposal, diversity was similar to adjacent inlets; however, the stations nearest the mine were different in detail. In an inlet receiving wastes from a groundwood plant, worms were virtually non-existent near the plant but increased to 91 species at the mouth of the fiord. In a nearby pristine inlet 126 species were recorded (Fournier et al., 1982). The diversity of bottom fauna near the Brittania Beach copper mine discharge was lowest and gradually increased from shallow to deep water stations and from tailings to non-tailings areas. Even 12 years after the discharge ended the diversity had not returned (Ellis and Hoover, 1990). The mine had disharged tailings for 75 years.  Areas directly under fish farms have a depauperate benthic fauna while the perimeter is characterized by an abnormal benthic assemblage dominated by one species of worm (Cross, 1990). No studies have yet been done to determine how fast areas would recover after removal of a fish farm.  These examples illustrate how pollution reduces the biological diversity of infaunal species.

Threats to Species Diversity

Paleontologists have documented numerous mass extinctions throughout geological time. The causes of these natural disasters are the subject of much speculation by scientists, from major volcanic eruptions to giant meteorites from space.  Ninety-eight percent of all the species that ever lived on earth are now extinct (Ehrlich, 1981).  So, what is the big deal you might ask. It is the rate of extinction that is concerning biologists today.  Many of the so-called mass extinctions actually took thousands of years.  During the elimination of the dinosaurs the extinction rate has been estimated at one extinction per 1000 years.  For much of this century the rate of human-caused extinctions was one per year.  But since 1960 the rate has skyrocketed to 1000 species lost per year (Norton, 1986).  Even if these estimates are an order of magnitude out, it is still a scary prospect to think that humans may cause their own mass extinction. After all, it is usually the animals at the top of the food chain that succumb first. Ehrlich estimates that species extinction in higher vertebrates is now roughly 100 times the average level for the past 50 million years. 

The main culprits for this accelerated extinction rate are thought to be the loss or degradation of habitat and direct harvesting by human activities (Vermeij, 1986).  This has been well illustrated by the destruction of tropical rain forests and the loss of the species they contain (Lovejoy, 1986). In the sea, coral reefs correspond to rain forests in species richness. Until recently no species extinctions have been noted in coral reef ecosystems. However, Glynn and de Weerdt (1991) reported perhaps the first documented extinction of a coral species.  They expressed concern that this event may be the harbinger of future extinctions should habitat destruction and coral reef bleaching events continue.

In temperate regions, old growth forests and kelp forests are similar in that each of them represents a stable ecosystem with a characteristic flora and fauna that have evolved together for thousands of years. The main difficulty in documenting the species and the ecology of a kelp bed or coral reef is easy access. Being air-breathing mammals we are allowed only brief forays into those environments with the aid of SCUBA equipment. It remains to be seen whether the few documented cases of species extinctions in the sea are real or an artifact of poor sampling. The most famous case of human-caused extinction in the sea is the over-harvesting of the Steller Sea Cow in the Aleutian Islands.  Only in the last few years have scientists been ringing the alarm bells about the need for more study of marine biodiversity (Beatley,1991; Earl, 1991; Eiswerth, 1990; Ray, 1991; Steele, 1991; Vermeij, 1989).

Our knowledge of marine invertebrates is still at a pioneering stage in B.C.  Much needs to be done to identify and document  distributions of species in all our coastal waters.  To illustrate the state of our knowledge, in 1974 a group of us from the Provincial Museum spent 2 months scuba diving and collecting in the area around Prince Rupert. During that time we collected at 34 sites. I paid particular attention to the nudibranchs. Thirty-one species were collected. Of these, 17 (55%) had not been recorded in that area before (Lambert, 1976). This is significant when we realize that nudibranchs are a popular group and yet still relatively unknown.

Since that paper was published another study by Millen (1989) in the area around Ketchikan, 100 km to the north, yielded 43 species of which 15 were new to the area and extended their known distribution north. Only 4 of the range extensions were species mentioned in Lambert (1976). The rest were all range extensions from the Vancouver Island region,  600 to 900 km to the south. In that same paper she also recorded the presence of a species that was previously known only from the Atlantic.

The second edition of a book on west coast nudibranchs (Behrens, 1991) lists 217 species, 57 more than the previous edition ten years earlier. In addition, the authors illustrated 20 more species that are yet to be named and described.  These examples from the nudibranchs could be repeated for many of the other invertebrate groups as well.  These studies characterize the state of our knowledge about species distributions in the marine waters of British Columbia.

On the west coast, habitat loss and modification has been limited, for the most part, to the areas close to shore, especially estuaries.  Although much to my surprise,  we were recently trawling the bottom at a depth of 1200 metres off the west coast of Vancouver Island and netted a collection of bathroom tiles!  Most of the world's population inhabits a narrow band beside the ocean, and so endangers the most productive part of the marine environment - coastal wetlands and fisheries of the continental shelf.  Human population growth is perhaps the single-most pressing problem on the earth because of the need for more living space and more food. In recent years, Louisiana has experienced losses of some 25,999 acres of coastal marshes each year, and North Carolina has witnessed losses of its pocosins at rates of more than 40,000 acres per year (Beatley, 1991). More than 50% of the world's population lives along coasts and on estuaries. In the USA 50% of the population lives near the coast; in Australia 80%.  The population of coastal areas have been growing at 3 times the rate of the nation as a whole (World Resource Institute, 1990).  Combine this with the fact that more that 99% of the global catch of marine fishes is taken within 320 kilometres of a coastline, and there is potential for direct conflict.

Toxic Effects on Marine Invertbrates


Polychlorinated biphenyls (PCB) are detrimental to the reproductive systems of marine mammals.  Levels in many marine mammals exceed 50 ppm, the amount above which most goods are considered as toxic waste!  These high values are the result of a process called bioaccumulation. PCB's in the sediment are first incorporated into the meiofauna.  With each successive level of the food pyramid the toxin becomes concentrated tenfold, with top carnivores receiving the highest dose.  Cummins (1988) estimates that of the 1.2 million tons of PCB's in the world, 31% has already been released into the environment. If the remainder were released it would be sufficient to eliminate a wide range of marine mammals.

Tributyltin (TBT), the active ingredient in antifouling paint, has been shown to cause the development of male genitals on female snails (imposex) (Alvarez and Ellis, 1990).  The incidence of imposex is directly correlated with proximity to marinas.  Schiewe et al (1991) have shown a direct cause and effect between aromatic hydrocarbons and liver tumors in bottomfish. A correlation between the two has been known for years.  In Puget Sound a once thriving Native Oyster industry came to an end in part due to sulfite waste liquor from pulp mills and over-exploitation.  Fiddler crabs near an oil-spill site showed long term reductions in recruitment and population density, behavioural changes and higher winter mortality (Capuzzo, 1990).  In most cases it is the invertebrates that first ingest the toxins from the sediment, and begin the bioconcentration. Adverse effects and corrective measures are usually only noted when higher animals that serve as our food become contaminated. The sublethal effects to all the intermediaries are poorly known and constitute a major gap in our knowledge.

Bioactive Compounds

On a more positive note, a long list of useful chemicals have been derived from marine organisms. Already almost a quarter of all medical prescriptions originate from plants or microorganisms (Ehrlich and Wilson, 1991).  Much publicity has been given to the potential of higher plants in tropical rain forests to provide many more chemicals for use in medicine.  Because plants are fixed and cannot escape predators, they have evolved a multitude of toxic chemicals that repel plant eaters.  This same idea also applies to organisms in the ocean, with one difference.  Animals make up a large proportion of the sedentary or sessile organisms. Thus, like plants,  sponges, sea squirts, hydroids, corals, or sea anemones have also developed chemicals that repel predators.

Scientists are only just beginning to assess the potentially useful molecules that may be present in marine species.   A Wealth of Wild Species (Myers 1983) presents an impressive list of chemicals already isolated from these animals.  An extract from octopus relieves hypertension. A Caribbean sponge produces a compound that acts against diseases caused by viruses.  An enzyme chitosanase from shells of shrimps, crabs and lobsters is a preventative against fungal infections.  Didemnin, derived from sea squirts, appears to attack 2 classes of viruses.  It is also reported to double the life expectancy of animals suffering from leukemia.

Cold causing viruses can be inhibited by an agent derived from seaweed.  One type of flu virus is resisted by extracts from three species of sea stars.  A Caribbean sponge produces a compound (Cytarabine) which is effective against herpes and encephalitis, and treats leukemia.  One hundred and twenty species of sponges have been screened for bioactive chemicals - almost half contain antibiotic substances.  An extract from clams, oysters and abalone called Paolin I, arrests many harmful bacteria including streptococci.  A related agent Paolin II inhibits herpes viruses and reduces some tumors.  Of the more than 2,000 species of marine life tested, about 40 % of the species with bioactive chemicals came from the corals and relatives. The list goes on. Scheuer (1990) reviews some recent progress in the biomedical potential of marine organisms.

A little closer to British Columbia, the screening of 40 marine sponges from the San Diego region found antimicrobial activity in 28 species (Thompson, Walker, Faulkner, 1985). The potential chemical storehouse in the sea has barely been tapped. A number of screening programs are under way.  A company in Washington state has begun testing marine species from the west coast (Majnarich, pers. comm.), and likewise, a federal lab in Halifax. Ideally, once the compounds are identified, they might be synthesized artificially. In this way humans can gain a benefit from the millions of "clinical trials" that have occurred in Nature through evolution.  Protective chemicals probably arose by random mutations as by-products of a particular metabolic pathway. More of the animals with the repellent survived to reproduce, and gradually dominate the gene pool.

Ecosystem Health


Humans and the ecosystem we live in are the product of millions of years of evolution.  We are still totally dependent on the biosphere to nourish ourselves.  Every piece of food we put in our mouths comes indirectly from the land or the sea.  It is at our peril that we poison our environment.  The spread of DDT and PCB throughout the globe thousands of miles from the original sources should be proof enough that what we do locally can have global consequences. After any mass extinction it is the dominant life form that usually succumbs. The loss of biodiversity, caused by human activities, is now proceeding at a rate greater than any previous so-called mass extinction. Being the dominant predator on the planet, we can control the extinction of our own species by changing our behaviour before it is too late. How do we identify incorrect behaviour?  Aldo Leopold (1968) summed it up this way. " A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community.  It is wrong when it tends otherwise."

Original Publication: Philip Lambert. 1994. Biodiversity of Marine Invertebrates in British Columbia.  Pp. 57 - 69. In Biodiversity in British Columbia, edited by L. Harding and E. McCullum. Ottawa: Environment Canada.   Reproduced with the permission of the Minister of Public Works and Government Services Canada, 1998, and with permission of Environment Canada.

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Please cite these pages as:

Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2017. Biodiversity of British Columbia []. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver.

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