“The Scientific Committee considered a review of the Ross Sea marine ecosystem and agreed that the region had experienced relatively little commercial exploitation, had a long history of scientific exploration, and constituted a unique natural location to study the effects of climate change on ecosystem processes.”
SC-CAMLR-XXI Para 3.11, Oct 2002
THE ROSS SEA, ANTARCTICA, WHERE ALL ECOSYSTEM PROCESSES STILL REMAIN FOR STUDY
CCAMLR document number: WG-EMM-02/60
SUMMARY: The Ross Sea is a well-defined embayment of Antarctica about the size of southern Europe, bounded by Victoria Land to the west; King Edward VII Peninsula, Marie Byrd Land, to the east; the Ross Ice Shelf to the south; and the Southern Ocean, Pacific Sector, to the north. Its waters are composed of two related biotic systems: the Ross Sea Shelf Ecosystem (RSShelfE) and the Ross Sea Slope Ecosystem (RSSlopeE). The RSShelfE is the last Large Marine Ecosystem on Earth (except the Weddell Sea) that has escaped direct anthropogenic alteration; the RSSlopeE, similar to all of Earth’s other marine ecosystems, has lost its large baleen whales but otherwise is intact. A huge multidisciplinary, international scientific effort has been invested in studies of the geology, physics and biology of the Ross Sea over the past 45 years. In particular the activities of the US, NZ and Italian Antarctic programs have been a model of international scientific cooperation and collaboration. The successful result is an incredible wealth of knowledge, including long-term biological data sets, not available anywhere else in the Antarctic, which has documented clear signals of climate forcing, as well as top-down influences not confused by human exploitation or activity. Ironically, much remains unknown about how these ecosystems function. The Ross Sea is off limits to mineral extraction, but pressures on its biological resources are growing. The economic value of the resources should be weighed against the value of the system as a unique scientific resource. The Ross Sea represents an unparalleled natural laboratory in which the results of different fishery management strategies can be modeled in the context of short-term and decadal variation in biological populations, with these models applied elsewhere in the Southern Ocean and the World.
ACQUIRING A ‘BASE DATUM OF NORMALITY’ FOR A MARINE ECOSYSTEM: THE ROSS SEA, ANTARCTICA
CCAMLR document number: WG-EMM-04/20
SUMMARY: The Ross Sea Shelf Ecosystem (RSShelfE) offers the last chance to understand ecological processes in a system where both top-down and bottom-up forcing are still intact. Elsewhere in Earth’s oceans the systems used for understanding ecological processes and fishery effects all have lacked significant, natural top-down forcing for such a long time that it is a concept rarely considered by researchers who currently investigate open-ocean systems. Herein, the importance of top-down forcing in pelagic and neritic marine ecosystems is reviewed with concrete evidence given for its existence in the current functioning of the RSShelfE. In spite of this unique evidence for the Antarctic region, much remains to be learned about cross-component interactions in the Ross Sea system. Should the RSShelfE be un-naturally altered, an easy accomplishment given increasing fishery pressure, we will have lost the last opportunity to understand the processes that take place in a healthy, complete marine ecosystem.
Managing Ecosystem Uncertainty: Critical Habitat and Dietary Overlap of Top- Predators in the Ross Sea Agenda
Item No(s): EMM 06 – 7
ROSS SEA BIOREGIONALIZATION, PART I: VALIDATION OF THE 2007 CCAMLR BIOREGIONALIZATION WORKSHOP RESULTS TOWARDS INCLUDING THE ROSS SEA IN A REPRESENTATIVE NETWORK OF MARINE PROTECTED AREAS IN THE SOUTHERN OCEAN
CCAMLR document WG-EMM-10/11
This report provides the scientific basis, validating the results of the CCAMLR Bioregionalization Workshop (2007) as well as the report of ASOC (2010), for identifying the Ross Sea as one of 11 areas deserving close scrutiny for inclusion in a network of marine protected areas. CCAMLR (2007) identified the Ross Sea as an area of high biodiversity on the basis of its high physical heterogeneity; ASOC (2010) compared characteristics of the Ross Sea to areas designated under various international agreements instituted to preserve biodiversity. The CCAMLR (2007) subsequently was endorsed in the joint meeting of CCAMLR’s Scientific Committee and the Environmental Protocol’s Committee on Environmental Protection (ATCM XXXII-CEP XII, Final Report, 2009). Considered herein is the Ross Sea shelf and slope, which is a smaller portion of the area identified in CCAMLR (2007) as “Ross Sea shelf”.
Waters overlying the Ross Sea continental shelf and slope comprise ~2.0% of the Southern Ocean, an area inconsequential in size from a global perspective. However, as shown by this summary of information — amassed from the national research programs especially of Italy, New Zealand, United Kindgom (during the “heroic” era), and United States — the Ross Sea not inconsequential is its biodiversity nor its disproportionate contribution to world populations of many well-known iconic Antarctic species. The data and information presented herein show that the Ross Sea:
- is the most productive stretch of the Southern Ocean and contains habitat for 32% and 26%, respectively, of the world populations of Adélie and emperor penguins (summer, molting, portion of wintering habitat); 30% of the world population of Antarctic petrels, 6% of Antarctic minke whale and perhaps 50% of Ross Sea killer whale (summer foraging); and 50-72% of the South Pacific sector Weddell seal population (year round habitat).
- contains the primary habitat for subadult growth and spawning recovery of an ecologically and scientifically important, migratory, Antarctic toothfish population;
- possesses a fauna, especially its notothenioid fish, that now comprise a unique, marine example of an evolutionary radiation known as a “species flock”; its confines contain 46 endemic species of fish and invertebrates as well;
- is a region of exemplary benthic biodiversity, including >500 species first described from Ross Sea specimens, some dating back 170 years, and thus providing a baseline of species’ occurrence patterns that can be used to identify ongoing changes caused by climate change;
- on the basis of projections made from current models in the Intergovernmental Panel on Climate Change array, is likely to be the last stretch of ocean on Earth, perhaps within the current century, that will support a sea-ice associated community of organisms;
- is the best studied stretch of high latitude, continental shelf ocean in the Southern Hemisphere, including its a) geologic history, geophysical characteristics, and characterization of its seafloor substrate; b) circulation; c) polynya-facilitated biogeochemical processes leading to extremely high primary production; d) benthic-pelagic coupling whereby water column production enriches the benthic community; e) diverse assemblage of benthic fauna, depending on substrate, slope, current velocities and biological interactions, and varying in age from thousands of years to successional stages of iceberg scour events; and f) paradoxically (in today’s world) low level of Ross Sea zooplankton abundance in the context of an unusually robust pelagic assemblage of numerous large fish, aerial birds, penguins, pinnipeds and whales, both toothed and baleen; and
- contains the longest, or near-longest data sets (~40-50 yrs), important to understanding effects of climate change on Antarctic marine biota: hydrography, pinniped demography, benthic community structure, toothfish prevalence variability, and penguin population change.
Owing to its low level, to date, of human impact (Halpern et al. 2008, Ainley 2010), the Ross Sea provides a valuable research opportunity to continue the concerted scientific efforts of the past 200 years to investigate, without interference from other factors (see ASOC 2010):
- climate change and its ecological effects without interference by other, direct anthropogenic impacts (indeed, climate change clearly has been altering the sea ice and oceanographic properties of the Ross Sea in a well documented fashion); and
- the dynamism inherent in both bottom-up and top-down forces that structure this foodweb.
Given, as detailed herein, the high level of endemism, the high biodiversity and the fact that several iconic species require the entire Ross Sea in order to survive and maintain their world-important populations, all of the shelf and slope, and their physical characteristics and biota, should be considered an ecological unit.
ROSS SEA BIOREGIONALIZATION, PART II: PATTERNS OF CO-OCCURRENCE OF MESOPREDATORS IN AN INTACT POLAR OCEAN ECOSYSTEM
CCAMLR Document WG-EMM-10/12
SUMMARY We report results of analyses of niche occupation among mesopredators in the Ross Sea region, Antarctica, considering three important components: 1) projected distribution and overlap across the surface of the ocean, 2) capacity to utilize differing amounts of the water column (foraging depth) and 3) diet. Species included were: Antarctic Minke Whale, Ross Sea Killer Whale (ecotype C), Crabeater Seal, Weddell Seal, Emperor Penguin, Adélie Penguin, Light-mantled Sooty Albatross, and Antarctic and Snow petrel. The apex predators, Leopard Seal and Killer Whale ecotype A/B, were not included because of their rarity and, therefore, lack of adequate sighting data on which to generate spatial models. We also did not have adequate data to model Arnoux’s Beaked Whales, Antarctic Toothfish nor Colossal Squid, which likely are also important mesopredators, particularly adult toothfish. We modeled mesopredator species distributions at a 5km/pixel scale, using environmental data and species presence localities from at-sea surveys and other sources. A machine learning, “maximum entropy” modeling algorithm (Maxent) was used to model spatial patterns of species’ probabilities of occurrence, and these data were used to identify areas of importance to species in a conservation prioritization framework (Zonation). Data on depth of diving and diet were taken from the literature.
Three patterns of horizontal spatial use of the Ross Sea were apparent: 1) Shelf Break: restricted mostly to the shelf break, which includes outer continental shelf and slope (Light-mantled Sooty Albatross); 2) Shelf and Slope: full use of both the shelf and the slope (Ross Sea Killer Whale, Weddell Seal); and 3) Marginal Ice Zone (MIZ; pack ice surrounding the Ross Sea post-polynya): combinations in which the slope is the main habitat but western and eastern portions of the shelf (where sea ice is persistent) are used as well (Minke whale, Crabeater Seal, penguins, petrels). Diet composition overlapped extensively, but use of foraging space was well partitioned by depth of diving. Horizontally, the entire suite of mesopredators used the entire shelf and slope in a mosaic pattern although, not necessarily during the same season.
Spatial modeling of species richness, supported by Zonation analysis, indicated the outer shelf and slope, as well as deeper troughs in the Ross Sea Shelf and Ross Island vicinity to be particularly important to the upper trophic level organisms of the Ross Sea. Our results substantially improve understanding of these species’ niche occupation previously only described using heuristic approaches.
The Case for Inclusion of the Ross Sea Continental Shelf and Slope in a Southern Ocean Network of Marine Reserves
Information Paper Submitted by ASOC to ATCM XXXIII
SUMMARY This paper outlines recently assembled information that reinforces the case for protection of the Ross Sea. As noted in ASOC’s (2010) paper on Marine Protected Areas (MPAs) for this ATCM, there is now a process in place for the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to take the necessary steps that – if pursued expeditiously – would enable completion of an initial representative network of marine spatial protection and management by 2012. ASOC encourages Antarctic Treaty Parties via the Committee for Environmental Protection (CEP) to recognise, adopt and engage in this process.
One priority for protection is the Ross Sea continental shelf and slope, an area embedded within one of the regions recognised by CCAMLR and the ATCM/CEP as priority areas for MPA designation. It clearly is of high global importance in terms of its biodiversity, evolutionary significance, disproportional presence of many charismatic high-latitude species, and potential as a climate refuge and reference zone for continued and future change. According to an independent analysis of human impacts on the world’s oceans, the Ross Sea is the least affected oceanic ecosystem remaining on Earth (Halpern et al. 2008). It would be the highest latitude habitat represented in a comprehensive and representative network of Southern Ocean MPAs. It has for decades been an area in which investigations have been underway on the interannual, decadal and long-term effects of climate change on the hydrography and biota of a high latitude system.
This paper outlines how the Ross Sea shelf and slope, which are only a part of the “Ross Sea” area identified by SC-CAMLR, fulfills the criteria for selecting sites under the auspices of the Antarctic Treaty and CCAMLR for the designation of marine spatial protection. For perspective, though the statutes do not directly apply to high seas areas (but rather areas under national jurisdiction), this paper makes comparisons with the special area criteria under the Convention for Biological Diversity and UNESCO’s World Heritage Sites. The Ross Sea benthos is especially rich and the abundance of its top predator species is unique. Since the shelf and slope contain most of the spawning/breeding, feeding, molting and wintering areas of these predators, ASOC submits that the Ross Sea should be protected as a unit.