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Deep impact: The rising toll of fishing in the deep sea

May 2002
Trends in Ecology & Evolution 17(5):242-245

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University of Exeter

The deep ocean is one of the last great wildernesses. Waters deeper than 1000 m cover an estimated 62% of the planet. In spite of more than 150 years of exploration, the ocean depths remain virtually unknown. Biological science has so far touched upon only one millionth of the deep-sea floor, but new technology is revealing unknown and exotic habitats as quickly as we look. Those technologies are also bringing the deep within reach of industry, with devastating consequences.

Deep-sea fish generally live longer than do those in shallow water. The longevity of rockfish species from the genus Sebastes (Pisces: Scorpaenidae) increases exponentially with their deepest depth of occurrence. (r 2 = 0.51.) Redrawn, with permission, from [14].

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Lophelia reef habitat at 273 m on the Sula Ridge, Norway, showing a cusk fish Brosme brosme. Photograph reproduced, with permission, from Andre Freiwald, University of Tübingen.

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Deep impact: the rising toll of fishing in the deep sea

Callum M. Roberts

The Early Edition link:

http://reviews.bmn.com/journals/atoz/latest?pii=S0169534701024417

http://reviews.bmn.com/journals/atoz/latest?jcode=tree

The deep ocean is one of the last great

wildernesses. Waters deeper than 1000 m

cover an estimated 62% of the planet. In

spite of more than 150 years of exploration,

the ocean depths remain virtually

unknown. Biological science has so far

touched upon only one millionth of the

deep-sea floor, but new technology is

revealing unknown and exotic habitats as

quickly as we look. Those technologies are

also bringing the deep within reach of

industry,with devastating consequences.

Cast a dredge over the side of a ship far out

to sea and the chances are that you will

raise a bucket full of mud and worms.

Sediment blankets much of the deep-ocean

floor [1] and was a source of endless tedium

for those lowering dredges and raising

mud during the three-year voyage of

HMS Challenger in the 1870s. This voyage

marked the first systematic look at the

biology of the deep sea. Perhaps all that

mud contributed to the suicide, two cases

of insanity and 61 desertions that are

among its lesser known achievements [2].

Dredges are still a mainstay of deep-sea

biology, but today they are supplemented

by a burgeoning array of sophisticated

technology. Remotely operated vehicles,

video, bottom landers, submarines and

sonar now provide windows on the deep

that are forcing us to rethink our notions of

life there. In the past few decades, we have

discovered remarkable new habitats –

spectacular hydrothermal vents, cold

seeps, gas hydrates and cold-water coral

reefs [3]. A closer look at seamounts and

canyons reveals them to be hotspots of

production that harbour diverse faunas

that are rich in unique species.

However, scientists are not the only

ones taking an interest in the deep. These

waters offer the prospect of lavish rewards

to mining, oil and gas exploitation, and

fishing concerns. In a new report prepared

for the World Wide Fund for Nature

(WWF) and World Conservation Union

(IUCN), scientists from the Southampton

Oceanography Centre and an expert on

international law present a primer in

deep-sea biology and explore current

and potential threats to deep water and

high-seas life [3]. Although deep-ocean

mining still lies in the future, fishing is

already causing great concern.

Fishing deeper

Deep-water fisheries began in the 1960s

and 1970s, coinciding with declines in

shallow-water stocks that stimulated the

development of new and more robust

fishing gear [4]. Larger vessels, more

powerful winches, stronger cables and

rockhopper trawls expanded greatly the

reach of fishing. The move to deep water is

being encouraged further by governments

offering grants and subsidies [5] in efforts

to alleviate hardship brought about by

the collapse of shallow-water fish stocks

caused by overfishing. Consequently, there

has been a worldwide scramble to exploit

these resources and 40% of the world’s

trawling grounds are now in waters deeper

than the continental shelves [6].

Early rewards from deep-sea fishing

can be great. For example, the orange

roughy Hoplostethus atlanticus fishery

began in the 1970s. It took off in the 1980s

when spawning aggregations were

discovered around deep seamounts off

New Zealand and southern Australia.

Catches from these aggregations could be

incredible, sometimes 60 t from a 20-min

trawl (J.A. Koslow, pers. commun.).

However, in just over a decade, stocks

collapsed to <20% of their pre-exploitation

abundance, largely through sequential

depletion of aggregations [4,7]. In the

North Atlantic, populations have met with

a similar fate. Here, the mainly French

fishery peaked at 4500 t during its first

two years, then dropped to 1000 t three

years later [5].

Other fisheries have also flourished

briefly then diminished. For example,

pelagic armourhead Pseudopentaceros

wheeleri were fished over seamounts in

international waters northwest of Hawaii

from the late-1960s to mid-1970s. In 1976,

30 000 t were landed but, the year after,

catches collapsed to just 3500 t and have

never recovered [8]. In the North Atlantic,

blue ling Molva dipterygia fisheries also

rely on spawning aggregations. As new

areas are rapidly depleted, the survival of

the fishery depends upon the continuing

discovery of unexploited aggregations [9].

We know from shallow waters that

unregulated or poorly controlled fishing of

aggregations is a quick ticket to fishery

collapse [10]. For example, throughout the

Caribbean, Nassau grouper Epinephelus

striatus spawning aggregations numbering

tens of thousands of fish were eliminated

in just a few years, never to reform [11].

Spawning aggregations concentrate fish

from a very large area into a very small

one. For example, orange roughy travel

hundreds of kilometres to spawn over

seamounts in the Southern Hemisphere

[12]. Aggregations can also form in other

ways. Adult pelagic armourhead, for

example, migrate to seamounts from broad

areas of the northern Pacific, and live out

the rest of their lives there [13]. Where

fishing effort is difficult to control, as it

is on the high seas, exploiting dense

aggregations can be closer to mining than

to fishing, because depletion is rapid and

recovery unlikely [10].

Deep-water fisheries fail the

sustainability test on another ground.

The almost glacial pace of life in the deep

makes it a particularly unsuitable place

to fish. Many species grow slowly and live

to extraordinary ages. For example, new

radiometric aging methods reveal that

rockfish Sebastes spp. longevity increases

exponentially with the deepest occurrence

of a species (Fig. 1), and some species can

reach 200 years old [14]. Cailliet et al. [14]

suggest that great longevity could be

facilitated by slow metabolism. In deep-sea

fish, metabolic rates are typically an order

of magnitude lower than in fish living near

the surface [15]. However, this is not the

only factor – some species dwelling on

seamounts have metabolic rates similar to

those of species living at the surface yet

still live to a great age, perhaps because of

low rates of predation [15].

Long lifespan is usually paired with

late reproduction. Icelandic roundnose

grenadier Coryphaenoides rupestris can

live to their 70s and mature at ~14–16

years old [16]. Orange roughy, which reach

150 years old, do not mature until their

mid-20s to mid-30s [17]. For shallow-water

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Deep impact: the rising toll of fishing in the deep sea

Callum M. Roberts

fish, a large body size and advanced age

at maturity are two of the most reliable

predictors of vulnerability to

overexploitation [18]. Long life, late

maturity and high fecundity are also

indicators of sporadic recruitment success

[18]. The life-history characteristics

of deep-sea species place them at the

extreme end of the vulnerability

spectrum. What these characteristics

point to is that deep-water fisheries are

repeating the process of sequential stock

depletion that has been the hallmark

of shallow-water fisheries [19]. The

difference is that depletion is more rapid,

and recovery will be much slower and even

less certain than in shallow water.

The collateral costs of deep-water

exploitation

Deep-sea fisheries are inflicting terrible

collateral damage. Only a handful of

species is marketable, largely because

most have soft, watery flesh that is

undesirable to consumers and of little use

for fishmeal [5]. Most species are discarded

as bycatch – bykill really, because there is

100% mortality of fish brought up from

great depths [20]. Furthermore, most

deep-sea species are adapted to conditions

of low turbulence. They have large scales,

weak skins and lack the well-developed

mucus coating of shallow water fish [21].

Fish that enter trawls are rapidly stripped

of their scales and skin, so that even small

fish that pass through trawl meshes

probably suffer heavy mortality.

Fisheries are concentrated into areas

with some of the greatest biological

significance in the deep sea. Seamounts,

together with steep slopes, such as those of

canyon walls, are among the few deep-sea

habitats where currents are strong enough

to prevent sediment accumulation. The

same currents also bring food, and a rich

benthic fauna of suspension feeders

develops as a result, including corals,

sponges, seafans and hydroids. This

constant input of food supplies the large

fish aggregations that have attracted

fishers. Koslow et al. [22] found 300 species

of fish and invertebrates inhabiting

Tasmanian seamounts. But many of these

seamounts have literally been stripped

bare by trawling. For example, there was

95% bare rock on fished peaks compared

with just 10% on unfished ones [22], and,

on average, unfished seamounts had

double the benthic biomass and 46% more

species than did fished areas.

The closer we look at the deep sea the

more we challenge our previous ideas.

De Forges et al. [23] reported >850 macro-

and megafaunal species from seamounts

of the southwestern Pacific. This is

striking when you consider that only

597 invertebrate species had been

recorded from seamounts between the

HMS Challenger expedition of the 1870s

and 1987. The new samples reveal

hitherto unsuspected levels of endemism.

Between 29% and 34% of the species

collected were potential seamount

endemics and new to science [23]. Many

species, it seems, have extremely limited

geographical distributions and are

restricted to closely spaced ranges of

underwater peaks. The potential for trawl

damage to cause extinctions is high [24].

Other habitats are being caught in

the fishing crossfire. It is only in the past

five years that the extent of coldwater

coral reefs in the North Sea has been

appreciated, although they were first

described over a century ago [25]. This

habitat occurs at depths of 100–2000 m

and is built largely by a single species of

coral Lophelia pertusa. Growing at rates

of just a few millimetres a year, over

millennia the corals have created reef-like

mounds that can reach up to 200 m high

and 4000 m long [26]. Off the Norwegian

coast, oil companies exploring the seafloor

with remotely operated video cameras

came across a region of reefs that extend

for 13 km [27]. Lophelia beds support a

rich assemblage of species (Fig. 2),

totalling >800 at the last count [28].

Evidence from video suggests that they

also form important nursery grounds for

many fish species.

Video and photographic surveys reveal

troubling evidence of the vulnerability of

this fragile habitat to fishing, including

deep parallel grooves of pulverized coral

ploughed by trawl doors [29]. These doors

keep the net open and the trawl on the

bottom, and deeper trawling and rougher

seabeds require heavier doors, which can

weigh 2–5 t each. Norwegian fishers have

long known of the presence of Lophelia

reefs and developed fishing techniques to

reduce net damage and increase catches

(although only over the short term), such

as dragging chains across the bottom

ahead of trawls to mow down obstructions.

At a recent symposium on deep-water

corals, Norwegian scientists estimated

that up to half of these reefs have already

been damaged or destroyed by fishing

(Fossa et al. 2000; http://home.istar.ca/

~eac_hfx/symposium/).

Across the Atlantic, there are similar

problems. To people fishing off Nova Scotia,

glass sponges are a nuisance. In newly

fished areas, they clog nets with literally

tonnes of material akin to fibreglass. Over

time, the problem diminishes as nets clear

the bottom of its biota. This process of

seabed habitat transformation has been

underway since the early days of trawling.

In the 19th and early 20th centuries,

fishers used to regularly trawl up giant

gorgonians [30]. Radioisotope aging of

smaller colonies put them at hundreds of

years old, suggesting ages of 2000 or more

for the largest specimens [30].

There are fishing methods that are

less destructive to deep-water habitats,

including long-lines, traps and gill nets.

However, the use of gill nets is still

problematic, because lost nets can

continue fishing for very long periods. In

shallow water, the fishing power of lost

nets is rapidly reduced by storms, tidal

currents and fouling algae, but in the calm

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250

200

150

100

01000800600400

Maximum depth of

occurrence (m)

2000

Longevity (y)

Fig. 1. Deep-sea fish generally live longer than do those

in shallow water. The longevity of rockfish species from

the genus

Sebastes

(Pisces: Scorpaenidae) increases

exponentially with their deepest depth of occurrence.

(

2=0.51.) Redrawn, with permission, from [14].

Fig. 2.

Lophelia

reef habitat at 273 m on the Sula Ridge,

Norway, showing a cusk fish

Brosme brosme

Photograph reproduced, with permission, from Andre

Freiwald, University of Tübingen.

and dark of the deep, nets remain lethal

for much longer. Fishing with long-lines

does less damage to habitats and there is

less wasted bycatch [21], but there is still

no way out of the problem of extremely

low rates of production. For example, the

sustainable annual take of orange roughy

in the southern ocean has been estimated

at only 1.5% of the unfished biomass [31].

Given the high costs of deep-sea fishing

(specialist gear, larger boats and long

voyages) it seems likely that it can be

profitable only if pursued in the present

mode of serial depletion. There is probably

no such thing as an economically viable

deep-water fishery that is also

sustainable. It is clear that the biology

of deep-sea organisms compels us to

rethink attitudes to exploitation that we

have developed from experience with

organisms living in the ‘fast-lane’ of

shallow seas. Merrett and Haedrich [32]

argue that we must consider deep-sea fish

stocks as nonrenewable resources.

Deep-sea ecosystems need urgent protection

The clear cutting of old-growth redwood

forests in the western USA during the

19th century spurred the creation of the

first national parks. The analogy is

obvious. Ancient groves of invertebrates

are being clearcut by trawling just as

quickly and surely as loggers felled groves

of giant redwoods [33]. The unique

megafauna of these hidden aquatic glades

is being hooked and netted faster than

they can possibly be replaced. As with

rainforests, we are probably losing species

far more quickly than we can describe

them. We urgently need to extend

protection to large areas of the deep sea.

Most deep-sea fishing is unregulated

[3], but no licensing, quota scheme or

effort control will save deep-ocean life,

because it can be depleted or destroyed

much too rapidly for these mechanisms

to work. The answer is to create marine

reserves that are entirely off limits to

fishing. Norway moved fast to protect

its coldwater coral reefs from trawling

in 1999, soon after their extent and

vulnerability became known. To date, no

other country has done so. In Australia,

twelve seamounts have been protected

from bottom fishing within the 370 km2

Tasmanian Seamounts Marine Reserve

(Dahl-Tacconi, 2000; http://home.istar.ca/

~eac_hfx/symposium/), New Zealand has

protected 19 seamounts and the USA has

created a small marine-protected area

encompassing two seamounts off Alaska

[34]. However, none is protected from

fishing all the way to the surface. It is still

unclear how closely linked benthic and

pelagic foodwebs are around seamounts.

For example, vertical migrations of

organisms transfer nutrients from shallow

water to bottom habitats. This, together

with the nutrient ‘snowfall’ from animals

aggregated higher in the water column

helps explain why seamount assemblages

are so rich [15]. Consequently, partial

protection measures might not assure

the long-term wellbeing of bottom-living

communities [20,35]. Surface to bottom

protection from fishing offers more security

but could be more difficult to implement due

to greater fishing industry opposition [36].

National initiatives represent a crucial

first step for deep-sea conservation, but

much of the deep lies beyond national

jurisdiction. Fifty percent of the planet

comprises high seas [3], which are outside

the 200-mile national limits. High-seas

regulation poses great challenges [37], but

as the new WWF–IUCN report shows,

present international laws provide a

framework for creating high-seas marine

reserves [3]. Unfortunately, the present

rate of expansion of deep-sea fisheries

gives us little time to act. Unless we

work quickly to establish reserves, we

might realize the Victorian vision of a

deep sea that is devoid of larger life – the

kingdom-of-the-worms once more.

Acknowledgements

This article is dedicated to the memory

of Don McAllister, who saw the need to

protect deep-sea habitats from fishing,

and worked hard to raise awareness

of what we are losing. Julie Hawkins

suggested many improvements to the

article. This work was supported by a Pew

Fellowship in Marine Conservation from

The Pew Charitable Trusts and The Hrdy

Fellowship in Conservation Biology at

Harvard University in the Dept of

Organismic and Evolutionary Biology.

I am very grateful to Sarah and Daniel

Hrdy for endowing the fellowship and to

Steve Palumbi for his hospitality.

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Callum M. Roberts

Environment Dept, University of York, York,

UK YO10 5DD.

e-mail: cr10@york.ac.uk

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Nov 2023
ICES J MAR SCI

Knowledge of fisheries impacts, past and present, is essential for understanding the ecology and conservation of seabirds, but in a rapidly changing world, knowledge and research directions require updating. In this Introduction and in the articles in this Themed Set "Impacts of fishing on seabirds" , we update our understanding of how fishing impacts seabird communities and identify areas for future research. Despite awareness of the problems and mitigation ef for ts for > 20 years, fisheries still negatively impact seabirds via the effects of bycatch, competition, and discards. Bycatch continues to kill hundreds of thousands of seabirds annually, with negative population-level consequences. Fisheries for forage fish (e.g. anchovy, sandeel, and krill) negatively impact seabirds by competing for the same stocks. Historically, discards supplemented seabird diets, benefitting some species but also increasing bycatch rates and altering seabird community composition. However, declining discard production has led to potentially deleterious diet switches, but reduced bycatch rates. To improve research into these problems, we make the following recommendations: (1) improve data collection on seabird-vessel interaction and bycatch rates, on fishing ef for t and vessel movements (especially small-scale fleets), and on mitigation compliance, (2) counter the current bias towards temperate and high-latitude ecosystems, larger-bodied species and particular life stages or times of year (e.g. adults during breeding), and (3) advance our currently poor understanding of combined effects of fisheries and other threats (e.g. climate change, offshore renewables). In addition, research is required on under-studied aspects of fishing impacts: consequences for depleted sub-surface predators, impacts of illegal, unreported and unregulated fishing, artisanal and emerging fisheries, such as those targeting mesopelagic fish, have received insufficient research attention. Some of these shortfalls can be overcome with new tools (e.g. electronic monitoring, remote sensing, artificial intelligence, and big data) but quantifying and addressing fishing impacts on seabirds requires greater research investment at appropriate spatio-temporal scales, and more inclusive dialogue from grassroots to national and international levels to improve governance as fishing industries continue to evolve. Background and motivation for a themed article set

Local ecological knowledge (LEK) suggests overfishing and sequential depletion of Peruvian coastal groundfish

Article

Nov 2023

Objective Fish populations targeted by recreational and artisanal fisheries remain largely unassessed in low‐ and middle‐income countries. This generally results in a lack of regulatory action from government agencies, thus aggravating the risk of overfishing. In this context, sources of historical information, such as local ecological knowledge (LEK), are key to providing insight on the status of fish populations and informing management. Systematized elicitation processes have increasingly shown an ability to produce quantitative indicators while reducing biases and caveats inherent to expert knowledge. In this study, we assessed changes in composition of the catch, species abundance, and geographical distribution of the catch for 10 data‐poor coastal groundfish species of Peru using LEK. Methods We designed and conducted a structured elicitation process to gather LEK on these species from 40 recreational and commercial spearfishers in Peru. We then used the obtained data to develop a set of indices and analyzed them statistically to identify trends and the magnitude of changes over time, if any, between the years 1960 and 2019. Result Our results show a significant decline in the relative participation (a species' catch proportion relative to the total catch) and abundance of seven assessed species in the catch as well as a major reduction in their geographical distribution. For some species, decreases in relative participation within the catch and decreases in average daily catch, a measure that may indicate changes in abundance, were statistically significant across the time span of the study. Average daily catch was between 1% and 15% of their historical high values. Some species have experienced a reduction of 60–100% in the geographical distribution of their catch. Conclusion Results suggests a scenario of overfishing and sequential depletion of the Galapagos Sheephead Wrasse Semicossyphus darwini , Pacific Goliath Grouper Epinephelus quinquefasciatus , Harlequin Wrasse Bodianus eclancheri , Grape‐eye Seabass Hemilutjanus macrophthalmos , Chino Medialuna ancietae , Pacific Beakfish Oplegnathus insignis , and Broomtail Grouper Mycteroperca xenarcha . We highlight how the application of expert elicitation methods can help to build LEK‐based fishery indicators that are useful for assessing data‐poor fisheries and providing critical information to prompt management discussions.

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea OPEN ACCESS EDITED BY

Article

Full-text available

Jul 2023

Due to their late maturation, extreme longevity, low fecundity and slow growth rates, deep-sea Chondrichthyes are extremely vulnerable to human impacts. Moreover, assessing the impact of deep-sea fisheries is difficult, as many species (including sharks) are part of the bycatch and are often discarded at sea, and/or landed under generic commercial-species codes. The lack of this information on fishery data sets and the limited availability of species-specific life history data make challenging the management of deep-sea Chondrichthyes. The kitefin shark Dalatias licha is a cosmopolitan elasmobranch, mainly found on continental and insular shelf-breaks and slopes in warm-temperate and tropical waters. This species is a common by-catch of the deep-sea trawling, considered as "Endangered" by the IUCN Red List for all European waters, Mediterranean Sea included. Here we present the results of a study based on a total of 78 specimens of kitefin shark collected over 3 years in the Ligurian Sea (NW Mediterranean) as by-catch from deep-water fisheries. Total length ranged from 380 to 1164 mm, and individual weight ranged from 198 to 8000 g. Immature and mature individuals showed a sex ratio dominated by males. Adult males were observed throughout the year, while mature females were observed only in spring-summer. These data lead to hypothesise a spatial segregation between genders. The kitefin shark diet was dominated by bony Frontiers in Marine Science fish (mainly Macrouridae) and other small sharks (e.g., Galeus melastomus and Etmopterus spinax), but their gut included plastic items and parasites. Data reported here underline the rarity, complex ecology and the threat for this shark species and support the urgency of promoting initiatives for their monitoring and conservation.

Long distance dispersal and oceanographic fronts shape the connectivity of the keystone sponge Phakellia ventilabrum in the deep northeast Atlantic

Article

Full-text available

Jun 2023

Little is known about dispersal in deep-sea ecosystems, especially for sponges, which are abundant ecosystem engineers. Understanding patterns of gene flow in deep-sea sponges is essential, especially in areas where rising pressure from anthropogenic activities makes difficult to combine management and conservation. Here, we combined population genomics and oceanographic modelling to understand how Northeast Atlantic populations (Cantabrian Sea to Norway) of the deep-sea sponge Phakellia ventilabrum are connected. The analysis comprised ddRADseq derived SNP datasets of 166 individuals collected from 57 sampling stations from 17 different areas, including two Marine Protected Areas, one Special Area of Conservation and other areas with different levels of protection. The 4,017 neutral SNPs used indicated high connectivity and panmixis amongst the majority of areas (Ireland to Norway), spanning ca. 2,500-km at depths of 99–900 m. This was likely due to the presence of strong ocean currents allowing long-distance larval transport, as supported by our migration analysis and by 3D particle tracking modelling. On the contrary, the Cantabrian Sea and Roscoff (France) samples, the southernmost areas in our study, appeared disconnected from the remaining areas, probably due to prevailing current circulation patterns and topographic features, which might be acting as barriers for gene flow. Despite this major genetic break, our results suggest that all protected areas studied are well-connected with each other. Interestingly, analysis of SNPs under selection replicated results obtained for neutral SNPs. The relatively low genetic diversity observed along the study area, though, highlights the potential fragility of this species to changing climates, which might compromise resilience to future threats.

First Data on the Age and Growth of Schmidt’s cod Lepidion schmidti (Moridae) from Waters of the Emperor Seamounts (Northwestern Pacific)

Article

Full-text available

Jun 2023

This study presents the first data of growth and age of Schmidt’s cod Lepidion schmidti, a rare and poorly studied member of the Moridae family (Gadiformes, Teleostei). The research was focused on the Emperor Seamounts area with the aim of investigating the age, growth rates, and longevity of this species. The analysis involved examining annual growth increments on sagittal otoliths. Data were taken from longline catches in 2014 and 2016, resulting in the collection of 140 individuals and the use of 70 otoliths for age determination. The results revealed that Schmidt’s cod can live for up to 49 years, with a mean age of 31.5 years in the catches. The relationship between body weight and total length was described by a power function, indicating positive allometric growth. The most suitable growth model for this species was determined to be the Von Bertalanffy growth equation. These results provide valuable insights to add to the limited knowledge of growth and age in the Moridae family and emphasize the long lifespan and slow growth of Schmidt’s cod.

Freshwater Meiofauna—A Biota with Different Rules?

Chapter

Mar 2023

Great divergences arise when comparing the ecology of meiofauna in freshwater and marine ecosystems. Emphasizing the main differences between freshwater meiofauna and their marine counterparts, we will go on a stepwise journey through three major frontiers in freshwater research, which in turn are hierarchically interrelated: biodiversity, community organization (e.g. food webs structure), and ecosystem processes (e.g. metabolism and organic carbon breakdown). The starting point of this chapter is one of the utmost frontiers, both in marine and freshwater research: meiofaunal diversity. Especially in freshwater ecosystems diversity becomes evident since, here, habitats extend as highly disconnected biotopes, each characterized by an often fundamentally different biocenosis. From the biodiversity level, we move up the theoretical hierarchy to assess the role of meiofauna as an integral part of benthic food webs. Recent research underlines the role of freshwater meiofauna as highly connected nodes and shows their pivotal role in the transfer of energy and carbon along food chains. Distributed over all trophic levels, this structure contrasts with the prevailing conception of meiofauna in food webs, where meiofauna often are considered rather marginal units. Finally, we apply allometric principles from the metabolic theory of ecology in order to assess the role of freshwater meiofauna in the functioning of the benthic systems. With a novel modelling framework we develop an analytical perspective, showing that secondary production of micro- and meiobenthic communities can predict microbial decomposition rates within the benthic interface. Our results demonstrate that productive micro- and meiobenthos act as catalysers in the system of organic carbon breakdown and recycling. These findings underline the relevance of freshwater meiofauna within the biogeochemical carbon cycle. The mechanistic forces behind the processes involved require future experimental research.

Deep-sea fisheries as resilient bioeconomic systems for food and nutrition security and sustainable development

Article

Oct 2023

Hidden Players—Meiofauna Mediate Ecosystem Effects of Anthropogenic Disturbances in the Ocean

Chapter

Mar 2023

Humans have used, and had effects on, marine ecosystems throughout history. As the human population and its economic activities increase, these effects intensify. Yet, our awareness and understanding of the long‐term, pervasive effects of anthropogenic disturbances on the seafloor, and the resident meiofauna, is far from complete. This chapter summarises research on the responses of marine meiofauna to the most widespread anthropogenic disturbances, including bottom-fishing, pollution, introduction of invasive species, and climate change. Anthropogenic disturbance and natural environmental dynamics interact to cause changes in the response of meiofauna species, either in the short-term, through effects on growth and development, or in the long-term, through genetic selection. Species-specific sensitivity to disturbance can propagate to community-level responses, mediated by shifts in interspecific interactions. Meiofauna responses to anthropogenic disturbance are commonly nonlinear and depend on the environmental context in which the disturbance occurs, on the scales at which meiofauna responses are observed, and on the extent to which the disturbance creates novel environments that differ from those to which the resident meiofauna are adapted. Although responses of meiofauna assemblages to anthropogenic disturbance are complex, in general severe disturbance leads to dominance by opportunistic species. The widespread replacement of habitat-specific ecological specialists by broadly-adapted ecological generalists and opportunists often results in biotic and functional homogenisation of once disparate biotas. Their small size, their life history characteristics, and their phylogenetically and functionally diverse species pool, all suggest that meiofauna are resilient, and there is little evidence for the local extinction of meiofauna from anthropogenically disturbed seafloor habitats. It therefore seems likely that meiofauna have the ability to adapt, and thrive, in response to most environmental changes. New horizons for future meiofauna research pertain to the extent to which the resistance or resilience of meiofauna to anthropogenic disturbance buffers ecosystem functioning against further change.

The Biology of Lophelia pertusa (Linnaeus 1758) and Other Deep-Water Reef-Forming Corals and Impacts from Human Activities.

Article

Full-text available

Jan 1999
INT REV HYDROBIOL

Alex David Rogers

Over the last twenty years, human exploitation has begun to have an impact in the deep sea, especially in the upper bathyal zone. This has mainly taken the form of deep-sea fishing but more recently oil exploration has extended beyond the continental shelf. Deep-water coral reefs occur in the upper bathyal zone throughout the world. These structures, however, are poorly studied with respect to their occurrence, biology and the diversity of the communities associated with them. In the North-East Atlantic the coral Lophelia pertusa has frequently been recorded. The present review examines the current knowledge on L. pertusa and discusses similarities between its biology and that of other deep-water, reef-forming, corals. It is concluded that L. pertusa is a reef-forming coral that has a highly diverse associated fauna. Associated diversity is compared with that of tropical shallow-water reefs. Such a highly diverse fauna may be shared with other deep-water, reef-forming, corals though as yet many of these are poorly studied. The main potential threats to L. pertusa in the North-East Atlantic are considered to be natural phenomena, such as slope failures and changes in ocean circulation and anthropogenic impacts such as deep-sea fishing and oil exploration. The existing and potential impacts of these activities on L. pertusa are discussed. Deep-sea fishing is also known to have had a significant impact on deep-water reefs in other parts of the world.

Grounding Pleistocene iceberg shape recent deep-water coral reefs

Article

Full-text available

Apr 1999
SEDIMENT GEOL

The widespread view that scleractinian corals in cold and deep waters of high latitudes are slow growing organisms that do not form reefs is challenged by the discovery of a huge coral reef over 13 km in length, 10 to 35 m in height and up to 300 m in width formed by the coral Lophelia pertusa in water depths of 270 to 310 m at 64°N on the Sula Ridge, Mid-Norwegian Shelf. Cruises in 1994, 1995 and manned submersible operations in May 1997 provide data and observations from which the structure and development of the Sula Ridge coral reef have been determined. The Fennoscandian icesheet retreated from the Mid-Norwegian shelf prior to 12,000 years before present and modern oceanographic conditions were established at 8000 years before present. Coral growth since that time has resulted in a large deep-water shelf reef for which recent stable isotopic studies have demonstrated high growth rates for these azooxanthellate cold-water corals. Information on the geometry of deep-water coral reefs and their environmental controls is still fragmentary, controversial and raises issues of conservation in this area of active fishing and oil exploration. This paper reports on the discovery of what is probably one of the largest deep-water coral reefs existing in the northeast Atlantic and indicates that its siting is due to post-glacial structures (iceberg plough marks), events (the second Storegga Slide) and local conditions on the seafloor. Surprisingly, reef accumulation rates on the Sula Ridge are comparable with those measured on tropical coral reefs.

Fully-Protected Marine Reserves: A Guide

Article

Full-text available

Jan 2000

Life history correlates of responses to fisheries exploitation

Article

Jan 1998

Genetics and the Races of Man

Article

Jan 1950

W. C. Boyd

Coral in deep water

Article

Jan 1997

J. Murray Roberts

Deep-Sea Demersal Fish and Fisheries

Article

Aug 1999
COPEIA

Setting the stage. Diversity and distribution of deep demersal fish. Morphological and life history adaptations. Aspects of fish production: general considerations and feeding. Aspects of fish production: growth and reproduction. Adding a trophic link: exploitation beyond the shelf. The ecology of fisheries. Pandora's box: reflections on the future.

Fisheries for orange roughy (Hoplostethus atlanticus) on seamounts in New Zealand

Article

Nov 1999
Oceanol Acta

Malcolm Clark

Major commercial fisheries for orange roughy (Hoplostethus atlanticus) occur on seamount features, which are widely distributed throughout the New Zealand region. When the fishery developed in the late 1970s to early 1980s, it occurred mainly on flat bottom, but over time has become more focused on seamounts. In the 1995–1996 fishing year, it is estimated that about 70 % of the catch of orange roughy within the New Zealand EEZ was taken from seamounts. Seamounts on the Chatham Rise have been fished for over ten years. Examination of commercial catch and effort data show strong declines in catch rates over time, and a pattern of serial depletion of seamount populations, with the fishery moving progressively eastwards to unfished seamounts along the southern margins of the Rise. Catch rates on seamounts in other regions of New Zealand have also generally shown a similar pattern of rapid decline. There is growing concern over the impact of trawling on seamounts, and the effects this can have on the benthic habitat and fauna, and the long-term sustainability of associated commercial fisheries.

Deep-Sea Biology. A natural history of organims at the deep-sea floor

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