Kelp forests are phyletically diverse, structurally complex and highly productive components of coldwater rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

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Kelp forest ecosystems: biodiversity, stability, resilience and future

Human tissue is structured mainly of self-assembled polymers (proteins) and ceramics (bone minerals), with metals present as trace elements with molecular scale functions. However, metals and their alloys have played a predominant role as structural biomaterials in reconstructive surgery, especially orthopedics, with more recent uses in non-osseous tissues, such as blood vessels. With the successful routine use of a large variety of metal implants clinically, issues associated with long-term maintenance of implant integrity have also emerged. This review focuses on metallic implant biomaterials, identifying and discussing critical issues in their clinical applications, including the systemic toxicity of released metal ions due to corrosion, fatigue failure of structural components due to repeated loading, and wearing of joint replacements due to movement. This is followed by detailed reviews on specific metallic biomaterials made from stainless steels, alloys of cobalt, titanium and magnesium, as well as shape memory alloys of nickel–titanium, silver, tantalum and zirconium. For each, the properties that affect biocompatibility and mechanical integrity (especially corrosion fatigue) are discussed in detail. Finally, the most critical challenges for metallic implant biomaterials are summarized, with emphasis on the most promising approaches and strategies.

Metallic implant biomaterials

Palaeoecology and evolution of marine hard substrate communities

This paper proposes that human expression of pain in the presence or absence of caregivers, and the detection of pain by observers, arises from evolved propensities. The function of pain is to demand attention and prioritise escape, recovery, and healing; where others can help achieve these goals, effective communication of pain is required. Evidence is reviewed of a distinct and specific facial expression of pain from infancy to old age, consistent across stimuli, and recognizable as pain by observers. Voluntary control over amplitude is incomplete, and observers can better detect pain that the individual attempts to suppress rather than amplify or simulate. In many clinical and experimental settings, the facial expression of pain is incorporated with verbal and nonverbal vocal activity, posture, and movement in an overall category of pain behaviour. This is assumed by clinicians to be under operant control of social contingencies such as sympathy, caregiving, and practical help; thus, strong facial expression is presumed to constitute and attempt to manipulate these contingencies by amplification of the normal expression. Operant formulations support skepticism about the presence or extent of pain, judgments of malingering, and sometimes the withholding of caregiving and help. To the extent that pain expression is influenced by environmental contingencies, however, "amplification" could equally plausibly constitute the release of suppression according to evolved contingent propensities that guide behaviour. Pain has been largely neglected in the evolutionary literature and the literature on expression of emotion, but an evolutionary account can generate improved assessment of pain and reactions to it.

/pdf/facial-expression-of-pain-an-evolutionary-account-5fdom5b8ec.pdf

Facial expression of pain: an evolutionary account.

Why do juvenile fish utilise mangrove habitats

We measured the rate of advance of urchin (Strongylocentrotus droebachiensis) feeding aggregations (fronts) as they destructively grazed kelp beds (Laminaria longicruris) at both a wave-exposed sit...

Destructive grazing, epiphytism, and disease: the dynamics of sea urchin - kelp interactions in Nova Scotia

To create a checklist of behaviours that caregivers could use to determine pain in non-verbal individuals with mental retardation, primary caregivers were recruited by the Division of Neurology and interviewed using a semistructured interview. Caregivers of 20 individuals were asked to recall two instances of short, sharp pain and two of longer-lasting pain and describe the individual's behaviour. Transcribed interviews were reviewed by two of the authors and sets of non-overlapping items were developed. Average age of the 20 individuals was 14.5 years (range 6 to 29 years) and language level averaged 10 months as scored by the MacArthur Communicative Development Inventory. All had mental retardation and 18 had epilepsy and spastic quadriplegia or hemiparesis. Thirty-one behaviours were extracted from the interviews. The specific behaviours were often different from one child to another but the classes of behaviours (Vocal, Eating/Sleeping, Social/Personality, Facial expression of pain, Activity, Body and limbs, and Physiological) were common to almost all children. Reliability of using the checklist on interviews was very good (kappa=0.77). The checklist has excellent content validity and will be useful for caregivers of cognitively-impaired, non-verbal individuals to report on pain behaviours. Further research is needed to additionally assess its validity and sensitivity.

Behaviours caregivers use to determine pain in non-verbal, cognitively impaired individuals

Recurrent outbreaks of a disease (paramoebiasis, caused by a marine amoeba Paramoeba invaclens) result in mass mortalit~es of sea urchins Strongylocentrotus droebachjensis in the rocky subtidal zone of the Atlantic coast of Nova Scotia (Canada). Recent epizootics in 1993 and 1995, l ~ k e those which occurred in the early 1980s, were associated with unusually warm sea surface temperatures (SST) in late summer/fall of each year Disease outbreaks were localized in 1993 and d.id not completely eliminate sea urchin populations, whereas a w~despread epizootic caused near-complete mortality over -130 km of coast (straight-llne d~stance) In 1995. lnteranr~ual differences in the extent of mortality were related to d~fferences in the temperature regime [peak tenlpcrdtures prevailed longer in 1995), which is consistent wlth previously descnbeci patterns The absence of mortality in 1994 is attributed to the inability of P invadens to survlve low (<O°C) winter temperatures, suggesting it is an exotic pathogen Recent outbreaks of paramoebiasls were associated with ~ncreased proximity to the coast of warm water masses In the summer/fall, as indicated by satellite-derived and ground-truthed charts of SST Intrusions of Gulf Stream water as warm-core nngs, which entrain and mix with shelf water, may contribute to coastal warming, although the frequency of ring formation was fairly constant among years (from SST charts, 1991 to 1995) Disease outbreaks during the past 2 decades have also been associated with years of relatively high trop~cal storm and hurricane activity in the northwest Atlantic (from records of the National Hurricane Center USA, 1976 to 1995), which may influence advection and mixing off Nova Scotia. These observations suggest that large-scale oceanographic and meteorologic processes may play a role in triggering epizootics by transporting the infective agent (if P. invadens is an exotic species) and/or creating environmental conditions conducive to the propagation of the disease. Because of the stochastic nature of these external events, the dynamics of the rocky subtidal ecosystem appear to be highly unpredictable. Severe disease outbreaks which eliminate sea urchins cause major changes in community structure as barren grounds, previously dominated by sea urchins. are colonized by kelps and other macroalgae. This has important implications for coastal fisheries, particularly the rapidly expanding sea urchin fishery.

https://www.int-res.com/articles/meps/152/m152p155.pdf

Recurrent outbreaks of disease in sea urchins Strongylocentrotus droebachiensis in Nova Scotia: evidence for a link with large-scale meteorologic and oceanographic events

The impact of predation on survival of juvenile sea scallops Placopecten magellanicus has important implications for the population dynamics and aquaculture of this species. In field experiments using tethered juvenile scallops, we examined the effect of biological and physical factors, such as prey size, predator and prey densitv, water temperature (season) and site, on mortality rates of scallops in Lunenburg Bay, Nova Scotia, Canada. The major predators of juvenile scallops were crabs Cancer irroratus and sea stars Asterias spp. In an experiment manipulating scallop density, crab predation rate increased significantly with scallop density, but crab density did not, suggesting a functional response. Sea star predation rate on scallops was not affected by scallop density. In a series of experiments with different slze classes of scallops tethered at different sites and seasons, and In different densities of surrounding scallops and predators, the effects of covariates on scallop survival times were assessed using the statistical procedure of survival analysis. Since the tethering technique affected crab and sea star predation differently, the competing causes of scallop mortality were analysed separately. Water temperature, site, and scallop density were the important variables affecting crab predation. There was a significant interaction between temperature and site, such that crab predation on scallops increased with temperature at one site and was independent of temperature at the other site. Predation by crabs also increased with scallop density and, to a lesser extent, with crab density. Water temperature and scallop size were the primary variables affecting sea star predation. Sea star predation on scallops increased with temperature and decreased with scallop size. The results of this study suggest options for minimizing predation of scallops by crabs and sea stars in bottom culture operations.

https://www.int-res.com/articles/meps/115/m115p243.pdf

Survival analysis of tethered juvenile sea scallops Placopecten magellanicus in field experiments: effects of predators, scallop size and density, site and season

Objective
As rates of total joint arthroplasty (TJA) for osteoarthritis (OA) rise, there is a need to ensure appropriate use. We undertook this study to develop criteria for appropriate use of TJA.

Methods
In prior work, we used qualitative methods to separately assess OA patients’ and arthroplasty surgeons’ perceptions regarding appropriateness of patient candidates for TJA. The current study reviewed the appropriateness themes that emerged from each group, and a series of statements were developed to reflect each unique theme or criterion. A group of arthroplasty surgeons then indicated their level of agreement with each statement using electronic voting. Where ≤70% agreed or disagreed, the criterion was discussed and revised, and revoting occurred. In standardized telephone interviews, OA patient focus group participants indicated their level of agreement with each revised criterion.

Results
Qualitative research in 58 OA patients and 14 arthroplasty surgeons identified 11 appropriateness criteria. Member-checking in 15 surgeons (including 5 who had participated in the qualitative study) resulted in agreement on 6 revised criteria. These included evidence of arthritis on joint examination, patient-reported symptoms negatively impacting quality of life, an adequate trial of appropriate nonsurgical treatment, realistic patient expectations of surgery, mental and physical readiness of patient for surgery, and patient-surgeon agreement that potential benefits exceed risks. Thirty-six of the original 58 OA patient focus group participants (62.1%) participated in the member-check interviews and endorsed all 6 criteria.

Conclusion
Patients and surgeons jointly endorsed 6 criteria for assessment of TJA appropriateness in OA patients. Prospective validation of these criteria (assessed preoperatively) as predictive of postoperative patient-reported outcomes is under way and will inform development of a surgeon–patient decision-support tool for assessment of TJA appropriateness.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/art.39124

Allan W. Hennigar

Papers

Destructive grazing, epiphytism, and disease: the dynamics of sea urchin - kelp interactions in Nova Scotia

Behaviours caregivers use to determine pain in non-verbal, cognitively impaired individuals

Recurrent outbreaks of disease in sea urchins Strongylocentrotus droebachiensis in Nova Scotia: evidence for a link with large-scale meteorologic and oceanographic events

Survival analysis of tethered juvenile sea scallops Placopecten magellanicus in field experiments: effects of predators, scallop size and density, site and season

Perspectives of Canadian Stakeholders on Criteria for Appropriateness for Total Joint Arthroplasty in Patients With Hip and Knee Osteoarthritis.