Identification

Title

Habitat point records from 1975-78 University of Bristol Severn Estuary littoral rock survey

Abstract

Zonation of algae and invertebrates was examined on rocky shores in the Severn estuary from 1975 to 1978. These shores were characterised by an absence of macro-algae from MLWS and below. Some littoral algae showed reductions in abundance during the study. In particular, Ascophyllum nodosum and Fucus serratus almost disappeared from the mid-shore at one site after 1976, and no significant recolonisation had occured by 1979. Animal species in general showed predictable and constant zonation patterns, but Littorina rudis, Patella vulgata and Eliminus modestus all exhibited decreased upper vertical limits in the upper reaches of the estuary. Three approaches were taken to interpret the zonation patterns of their changes. 1. Exposure to wave action was estimated. Decreasing exposure levels may account for the decline in upper vertical limits of species in the upper estuary. 2. A survey of silt, salinity and temperature was carried out over compelte tidal cycles. High silt concentrations may partially explain the absence of macro-algae below MHWS. 3. Preliminary experiments compared the effects of grazers in the estuary with those in fully marine conditions. These experiments point to some of the factors which are responsible for the lack of algal recolonisation on the shore from which the dominant fucoids disappeared after 1976, but the situation is complex and involves algal reproductive biology as well as grazer activity.

Resource type

dataset

Resource locator

http://data.jncc.gov.uk/data/21c3db93-9ba0-4cbc-ad21-1a2ffedc4729-1975-78-University-of-Bristol-Severn-Estuary-littoral-rock-survey.csv

name: 1975-78-University-of-Bristol-Severn-Estuary-littoral-rock-survey.csv

Unique resource identifier

code

21c3db93-9ba0-4cbc-ad21-1a2ffedc4729

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Additional information source

Little, Smith (1980) Vertical zonation on rocky shores in the Severn estuary. Little, Boyden (1976) Variations in the fauna of particulate shores of the Severn estuary

Classification of spatial data and services

Topic category

oceans

Keywords

Keyword set

keyword value

Marine

Marine Recorder

JNCCMNCR10000490

Habitat

MNCR

Geographic location

West bounding longitude

-2.992824482

East bounding longitude

-2.622325537

North bounding latitude

51.60718383

South bounding latitude

51.37983632

Temporal reference

Temporal extent

Begin position

1978-01-01

End position

1978-12-31

Dataset reference date

date type

publication

effective date

2001-08-21

Frequency of update

Quality and validity

Lineage

This survey was extracted from a Marine Recorder snapshot.

Conformity

Data format

name of format

Comma Separated Values

version of format

Unknown

Constraints related to access and use

Constraint set

Use constraints

Open Government Licence v3.0

Limitations on public access

no limitations

Responsible organisations

Responsible party

organisation name

Digital and Data Solutions, JNCC

email address

data@jncc.gov.uk

responsible party role

custodian

Metadata on metadata

Metadata point of contact

organisation name

Digital and Data Solutions, JNCC

email address

data@jncc.gov.uk

responsible party role

pointOfContact

Metadata date

2018-05-17

Metadata language